CN115498634A - Power circuits and electrical equipment - Google Patents

Abstract

The invention discloses a power supply circuit and electrical equipment. The power supply circuit includes: a detection circuit and a control circuit; the input end of the detection circuit is connected to alternating current, the output end of the detection circuit is connected to the control end of the control circuit, and the output end of the control circuit is connected to the electrical equipment Control system; the detection circuit is used to output a power-down signal after detecting the first preset duration of AC power-down; the control circuit is used to perform voltage modulation or working frequency modulation based on the power-down signal, so that The duration of maintaining the voltage transmitted to the control system is extended to a second preset duration. The power supply circuit can use the detection circuit to detect the AC power failure, and use the control circuit to extend the output holding time. Without increasing the AC power failure signal line and the structure without increasing the output capacitor, it solves the short output retention time when the AC power failure occurs. The problem is conducive to meeting the power-down protection requirements.

Description

Power circuits and electrical equipment

technical field

The invention relates to the technical field of power supplies. More specifically, it relates to a power circuit and electrical equipment.

Background technique

In electrical equipment such as TVs, washing machines, refrigerators, etc., the power supply generally has multiple power outputs, and the most important two power outputs are the control system power supply output and the power system power supply output. The output power of the system power supply is relatively large. With the intelligentization of various electrical equipment, the control system usually monitors the operating status of electrical equipment in real time, collects a large amount of data for storage, and uses the stored data for more intelligent control. Therefore, the control system of these electrical equipment does not allow sudden power failure during data storage and communication, so as to avoid data loss or even storage device damage caused by power failure. Therefore, the control system needs to receive power failure information before power failure, and Make corresponding power-down protection actions.

In the related art, the power failure protection can be implemented in combination with the main control board, but usually a signal line needs to be led from the power board where the power supply circuit is located to the main control board to realize signal transmission. Or, use the electrolytic capacitor inside the power supply circuit. When the output decreases, use the energy stored in the output electrolytic capacitor to supply power to the electrical equipment; in this way, it is necessary to set a larger-capacity electrolytic capacitor to supply power to the equipment to ensure that the equipment can have sufficient time to store data. However, if the capacity of the electrolytic capacitor is too large, the electrolytic capacitor cannot be charged to the output voltage value in time when the power is turned on, so that feedback cannot be established and eventually the power will fail to start. Therefore, the capacity of the electrolytic capacitor should not be too large, so that the electric energy output by the electrolytic capacitor can only be maintained for a short time, which is not conducive to meeting the power-down protection requirements.

Contents of the invention

In order to solve the problems described in the above-mentioned background technology, some embodiments of the present invention provide a power supply circuit and electrical equipment, which overcome the existing problems of using signal lines and electrolytic capacitors, and the short output maintenance time, without increasing the AC drop Under the electric signal line and the structure without increasing the output capacitance, the output maintenance time is prolonged, which is beneficial to meet the power-down protection requirements.

The invention provides a power supply circuit, including: a detection circuit and a control circuit;

The input end of the detection circuit is connected to alternating current, the output end of the detection circuit is connected to the control end of the control circuit, and the output end of the control circuit is connected to the control system of the electrical equipment;

The detection circuit is configured to output a power-off signal after detecting a first preset duration of AC power-off;

The control circuit is used for performing voltage modulation or operating frequency modulation based on the power-down signal, so as to extend the holding time of the voltage transmitted to the control system to a second preset time.

The present invention also provides an electrical device, comprising:

display screen;

a power system electrically connected to the display screen, and the power system is used to drive the display screen to display images;

a control system electrically connected to the power system;

In any one of the above power supply circuits, the output end of the power supply circuit is connected to the control system, and the power supply circuit is used to supply power to the control system.

It can be seen from the above technical solutions that some embodiments of the present invention propose a power supply circuit, by setting the power supply circuit to include a detection circuit and a control circuit; and the input end of the detection circuit is connected to alternating current, and the output end of the detection circuit is connected to The control terminal of the control circuit, the output terminal of the control circuit is connected to the control system of the electrical equipment; the detection circuit is used to output a power-down signal after detecting the first preset duration of the AC power failure; the The control circuit is used to perform voltage modulation or operating frequency modulation based on the power-off signal, so that the duration of the voltage transmitted to the control system is extended to a second preset duration, so that the power supply circuit can use detection for AC power-off The circuit is used for detection, and the control circuit is based on voltage modulation or working frequency modulation to extend the output holding time. Without increasing the AC power-off signal line and the structure of the output capacitor, the problem of short output holding time when the AC power is off is solved. , which is conducive to meeting the power-down protection requirements.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, for those of ordinary skill in the art, on the premise of not paying creative labor, Further drawings can also be derived from these drawings.

FIG. 1 is a schematic diagram of an application scenario according to an exemplary embodiment of the present invention;

Fig. 2 is a schematic diagram showing a detailed structure of an application scenario according to an exemplary embodiment of the present invention;

Fig. 3 is a schematic waveform diagram of a voltage conversion according to an exemplary embodiment of the present invention;

Fig. 4 is a schematic structural diagram of a power supply circuit according to an exemplary embodiment of the present invention;

Fig. 5 is a schematic structural diagram of another power supply circuit according to an exemplary embodiment of the present invention;

Fig. 6 is a schematic structural diagram of another power supply circuit according to an exemplary embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a rectifier circuit according to an exemplary embodiment of the present invention;

Fig. 8 is a timing diagram according to an exemplary embodiment of the present invention;

Fig. 9 is a schematic structural diagram of a coupling sub-circuit according to an exemplary embodiment of the present invention;

FIG. 10 is a schematic structural diagram of another coupling subcircuit according to an exemplary embodiment of the present invention;

Fig. 11 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention;

Fig. 12 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention;

Fig. 13 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention;

Fig. 14 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention;

Fig. 15 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention;

Fig. 16 is a schematic structural diagram of a detection sub-circuit according to an exemplary embodiment of the present invention;

Fig. 17 is a schematic structural diagram of another detection sub-circuit according to an exemplary embodiment of the present invention;

Fig. 18 is another timing diagram according to an exemplary embodiment of the present invention;

Fig. 19 is a schematic diagram of a gain curve according to an exemplary embodiment of the present invention;

Fig. 20 is a schematic structural diagram of another power supply circuit according to an exemplary embodiment of the present invention;

Fig. 21 is a schematic structural diagram of a control circuit according to an exemplary embodiment of the present invention;

Fig. 22 is a schematic structural diagram of another control circuit according to an exemplary embodiment of the present invention;

Fig. 23 is a schematic structural diagram of another control circuit according to an exemplary embodiment of the present invention;

Fig. 24 is a schematic structural diagram of an electrical device according to an exemplary embodiment of the present invention.

detailed description

In order to make the purpose and implementation of the present invention clearer, the exemplary implementation of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the exemplary embodiment of the present invention. Obviously, the described exemplary embodiment is only the present invention. Some, but not all, embodiments are invented.

It should be noted that the brief description of terms in the present invention is only for the convenience of understanding the implementations described below, and is not intended to limit the implementations of the present invention. These terms are to be understood according to their ordinary and usual meaning unless otherwise stated.

The terms "first", "second", and "third" in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar or similar objects or entities, and do not necessarily mean limiting specific sequential or sequential unless otherwise noted. It is to be understood that the terms so used are interchangeable under appropriate circumstances.

The terms "comprising" and "having", as well as any variations thereof, are intended to be inclusive but not exclusive, for example, a product or device comprising a series of components is not necessarily limited to all components expressly listed, but may include not expressly listed other components listed or inherent to these products or equipment.

Fig. 1 is a schematic diagram of an application scenario according to an exemplary embodiment of the present invention. As shown in FIG. 1 , the power supply circuit 10 can be used to supply power to other power consumption systems. Exemplarily, the application scenario may include: a power supply circuit 10, a control system 20, and a power system 30; the control system may also be called a data processing circuit, and the power system may also be called a power circuit. The output terminals of the power supply circuit 10 are respectively electrically connected to the control system 20 and the power system 30 , and the power supply circuit 10 is used to convert the alternating current of the commercial power into direct current and supply power to the control system 20 and the power system 30 .

Exemplarily, Fig. 2 is a schematic diagram showing a detailed structure of an application scenario according to an exemplary embodiment of the present invention. On the basis of Fig. 1, as shown in Fig. 2, the power supply circuit 10 includes: a filter circuit 110, a power frequency rectification circuit 120, a power factor correction (Power Factor Correction, PFC) circuit 130, a DC conversion circuit 140 and an output rectification circuit 150; wherein, the DC conversion circuit 140 includes a first direct current/direct current (DC/DC) converter 141 and a second DC/DC converter 142, and the output rectification circuit 150 includes a first output rectification circuit 151 and a second output rectification circuit 152 .

Wherein, the input end of the filter circuit 110 is electrically connected to the mains, the output end of the filter circuit 110 is electrically connected to the input end of the power frequency rectification circuit 120, and the output end of the power frequency rectification circuit 120 is electrically connected to the input end of the PFC circuit 130, The output end of the PFC circuit 130 is electrically connected with the input end of the first DC/DC converter 141 and the input end of the second DC/DC converter 142 respectively; The output end of the first DC/DC converter 141 is rectified with the first output The input end of the circuit 151 is electrically connected, the output end of the first output rectification circuit 151 is electrically connected to the input end of the control system 20, the output end of the second DC/DC converter 142 is electrically connected to the input end of the second output rectification circuit 152 , the output terminal of the second output rectifying circuit 152 is electrically connected to the input terminal of the power system 30 .

On this basis, with reference to FIG. 3 , the voltage conversion realized by the power supply circuit 10 will be exemplarily described.

Exemplarily, Fig. 3 is a schematic waveform diagram of a voltage conversion according to an exemplary embodiment of the present invention. On the basis of Fig. 2, as shown in Fig. 3, the commercial power can usually provide an alternating current Vac, and the alternating current Vac can be expressed as a sine wave signal, for example, the commercial power can provide 220V alternating current. There are some clutter electrical signals in the AC Vac provided by the mains, and the filter circuit 110 can filter out the clutter electrical signals in the AC Vac, so as to prevent the clutter electrical signals in the AC Vac from causing damage to subsequent circuits. Then, the power frequency rectification circuit 120 can rectify the alternating current output by the filter circuit 110, that is, rectify the alternating current after filtering out the clutter electric signal, obtain the direct current Vdc shown in FIG. 3 , and output the direct current Vdc to the PFC circuit 130. Then, the PFC circuit 130 can control the current waveform of the direct current Vdc output by the power frequency rectification circuit 120 to be synchronized with the voltage waveform of the direct current Vdc output by the power frequency rectification circuit 120 . Thereafter, the DC conversion circuit 140 performs step-down processing on the synchronized DC power; specifically, the first DC/DC converter 141 may perform step-down processing on the synchronous DC power output by the PFC circuit 130 to obtain a step-down process as shown in FIG. 3 . The step-down synchronous direct current Vdc1 output by the first DC/DC converter 141 is suitable for the control system 20 . The second DC/DC converter 142 can step down the synchronous direct current output by the PFC circuit 130 to obtain the step-down synchronous direct current Vdc2 as shown in Figure 3, and the step-down synchronous direct current Vdc2 output by the second DC/DC converter 142 Suitable for power system 30. The first output rectification circuit 151 can rectify the step-down synchronous direct current Vdc1 output by the first DC/DC converter 141, and output the rectified step-down synchronous direct current Vdc1 to the control system 20, so that the power supply circuit 10 can The alternating current Vac is converted into direct current Vdc1 suitable for the control system 20 and supplies power to the control system 20 . The second output rectification circuit 152 can rectify the step-down synchronous direct current Vdc2 output by the second DC/DC converter 142, and output the rectified step-down synchronous direct current Vdc2 to the power system 30, thus, the power supply circuit 10 can also Convert the alternating current Vac to the direct current Vdc2 suitable for the power system 30 and supply power to the power system 30 .

Exemplarily, the above-mentioned control system 20 and power system 30 may be systems integrated in electrical equipment, such as televisions, washing machines, refrigerators and other electrical equipment. With the intelligent development of various electrical equipment, in electrical equipment, the control system usually detects the operating status of electrical equipment in real time, collects a large amount of data for storage, and uses the stored data for control feedback to achieve more intelligent control . Therefore, the control system of these electrical equipment does not allow sudden power failure during the process of storing data and communicating with the superior control system, so as to avoid data loss or even storage device damage due to power failure. For this, the control system needs to receive power-down information (also called power-off information) before power-down (also called power-off), and take corresponding power-down protection actions (power-off protection actions).

In related technologies, there are mainly two methods for identifying power-down information, and both are implemented based on a main control board in an electrical device. Taking TV as an example, the power board where the power circuit is located is electrically connected to the main control board through a single signal line, and the AC power-down signal corresponding to the power circuit is transmitted to the main control board through this signal line. , the level of the AC power-down signal transmitted to the main control board changes, such as a high-low level conversion; after the main control board receives the power-down information, it immediately executes the protection action of the storage device, and then controls the electrical appliance after the protection action is completed. The device shuts down. The disadvantage of this method is that it is necessary to lead a signal line from the power supply board to the main control board separately, resulting in high complexity of the circuit structure.

Another method is that the main control board detects the output voltage of the power board in real time, and when the detected output voltage drops to a certain voltage, it considers that the AC power is off, and starts to execute the protection action of the storage device. The disadvantage of this method is: after the AC power failure, the voltage in the input capacitor of the power supply circuit decreases, and the power supply circuit will cause insufficient gain due to the decrease of the input voltage while the output voltage remains unchanged, and then stop working; the output holding time at this time can only be Relying on the output electrolytic capacitor to maintain, so in the electrical equipment that realizes power-off protection based on this method, the power supply circuit system needs to have a large-capacity output electrolytic capacitor. In a switching power supply system, the output capacitor cannot be increased infinitely. If the capacity is too large, the feedback cannot be established because the capacitor cannot be charged to the output voltage value in time when the power supply starts, which will lead to startup failure. Therefore, only the output capacitor with the largest capacity can be set, and relying on this type of output electrolytic capacitor can only be maintained for a short period of time. Therefore, for some electrical equipment that requires a long time for power-down protection, the method based on the output electrolytic capacitor , unable to meet the needs of power-down protection.

Aiming at at least one of the above-mentioned problems, the embodiment of the present invention proposes a method for identifying AC power failure and passing the voltage Modulation or operating frequency modulation to extend the output hold time of the power supply circuit and electrical equipment including the power supply circuit.

Exemplarily, an embodiment of the present invention provides a power supply circuit used in electrical equipment such as televisions, washing machines, refrigerators, etc., so as to realize the control of the power-down sequence in the switching power supply and prolong the output holding time to meet the needs of power-down protection . Specifically, a detection circuit and a control circuit are added to the power supply circuit in the related art, wherein the detection circuit detects the AC power failure, and when detecting the first preset duration of the AC power failure, outputs the power failure signal to the control circuit; and the control circuit performs voltage modulation or operating frequency modulation based on the received power-down signal, so that the voltage at the output end of the power circuit, that is, the duration of the voltage output to the control system is extended to a second preset duration, which is beneficial to Complete the power-down protection action to meet the power-down protection requirements.

The power supply circuit and electrical equipment provided by the embodiments of the present invention will be described exemplarily below with reference to the accompanying drawings.

Exemplarily, Fig. 4 is a schematic structural diagram of a power supply circuit according to an exemplary embodiment of the present invention. As shown in FIG. 4 , the power supply circuit 10 includes: a detection circuit 170 and a control circuit 190; herein, the detection circuit is an AC power failure detection circuit; the control circuit is a switching power supply control circuit, also called an output control circuit.

Wherein, the input end of the detection circuit 170 is connected with AC power, that is, the detection circuit 170 is an AC input. Exemplarily, the AC input may correspond to AC power, such as commercial power, or correspond to filtered AC power, or correspond to filtered and rectified AC power, which is not limited here, and will be exemplified later. .

Wherein, the output end of the detection circuit 170 is connected to the control end of the control circuit 190 , and the output end of the control circuit 190 is connected to the control system 20 of the electrical equipment. Exemplarily, the electrical device may be an electrical device such as a TV, which is not limited herein.

In the embodiment of the present invention, the detection circuit 170 is used to output a power-down signal after detecting the first preset duration of the AC power-down; the control circuit 190 is used to perform voltage modulation or operating frequency modulation based on the power-down signal, so that the transmission The hold time of the voltage to the control system 20 is extended to a second preset time.

Thus, the detection circuit 170 can detect the AC power, and when detecting the AC power failure, based on its own circuit structure characteristics, the time to output the power-down signal is after the first preset time period for detecting the AC power failure. Correspondingly, the control circuit 190 receives the power-down signal output by the detection circuit 170, that is, receives the power-down signal after the first preset duration of the AC power-down, and performs voltage modulation or operating frequency modulation based on the AC power-down signal, so that The voltage output by the power supply circuit, that is, the voltage output to the control system 20 is maintained for a period extended to a second preset period. Since the duration corresponding to the second preset duration is longer, it is beneficial for the control system 20 and related systems such as the main control board in the electrical equipment to complete the power-down protection action within the longer duration, thereby satisfying the power-down protection requirement.

Among them, the voltage modulation can use the power-off signal to pull down the standby signal of the main control board, so that the main control board can judge whether there is an AC power-off through the level conversion of the standby signal; that is, when the AC power is off, the standby signal is Pull low, the high level output by the main control board is pulled low, and the main control board can judge that the AC power is off. At this time, although the input voltage of the power circuit decreases, the output voltage also decreases, so the power circuit can continue to work for a period of time, thus prolonging the output holding time, which is beneficial to make the output time meet the requirements of the main control board and the control system to perform power-down The need for protective action.

Wherein, the working frequency modulation can use the power-down signal as a control signal, and after receiving the power-down signal, the working frequency is fixed, so that as the input voltage decreases, the working frequency does not decrease, and the gain remains unchanged; thus, When the input voltage is reduced, the output voltage is also reduced, and there is no longer any protection performed due to excessive gain, so the power circuit can continue to work under the condition of low input voltage, and the energy stored in the input electrolytic capacitor of the power circuit can be maximized The output is transmitted to the output terminal to extend the output hold time, so that the output time can meet the needs of the main control board and the control system to perform power-down protection actions.

Regarding the realization of the voltage modulation and the working frequency modulation, an exemplary description will be given later in combination with the structure of the power supply circuit.

The embodiment of the present invention provides a power supply circuit 10, the power supply circuit 10 includes a detection circuit 170 and a control circuit 190; the detection circuit 170 can detect the alternating current, and output the power off after detecting the first preset duration of the alternating current power failure Electric signal; the control circuit 190 receives the power-down signal, and performs voltage modulation or operating frequency modulation based on the power-down signal, so that the output of the power supply circuit 10 is maintained for a period of time extended to a second preset period of time, thereby increasing the output of the power supply circuit The holding time is beneficial to meet the power-down protection requirements.

In some embodiments of the present invention, FIG. 5 is a schematic structural diagram of another power supply circuit according to an exemplary embodiment of the present invention. On the basis of Fig. 2 and Fig. 4, as shown in Fig. 5, the power supply circuit 10 may also include a rectification circuit 160; wherein, the rectification circuit 160 is connected between the detection circuit 170 and the filter circuit 110 for filtering the The alternating current is rectified, and the rectified alternating current is transmitted to the detection circuit 170 so that the detection circuit 170 can detect the filtered and rectified alternating current.

In some embodiments of the present invention, FIG. 6 is a schematic structural diagram of another power supply circuit according to an exemplary embodiment of the present invention. As shown in Figure 6, in the power supply circuit 10, the detection circuit 170 includes a detection subcircuit 171 and a coupling subcircuit 172; the output terminal of the detection subcircuit 171 is electrically connected to the input terminal of the coupling subcircuit 172, and the output terminal of the coupling subcircuit 172 Connect the control terminal of the control circuit 190; the detection sub-circuit 171 is used to maintain the output voltage of the detection sub-circuit 171 greater than or equal to the preset voltage within the first preset time period when the voltage of the full-wave rectified alternating current drops; coupling The sub-circuit 172 is configured to output a power-down signal when the output voltage of the detection sub-circuit 171 is lower than a preset voltage; the first preset duration is greater than or equal to the valley duration of the full-wave rectified AC power.

In some embodiments of the present invention, the power supply circuit 10 includes: a detection subcircuit 171, a coupling subcircuit 172 and a control circuit 190, the output terminal of the detection subcircuit 171 is electrically connected to the input terminal of the coupling subcircuit 172, and the coupling subcircuit 172 The output end is electrically connected to the control end of the control circuit 190 , and the output end of the control circuit 190 is electrically connected to the control system 20 .

Wherein, the detection sub-circuit 171 is used to maintain the output voltage ACON of the detection sub-circuit 171 greater than or equal to the preset voltage U within the first preset time period when the voltage of the full-wave rectified alternating current drops, and when the output voltage ACON is less than the preset voltage U, When the voltage U is set, a signal is output to the coupling sub-circuit 172 .

Wherein, the coupling sub-circuit 172 is used for receiving the signal output by the detection sub-circuit 171 when the output voltage ACON is lower than the preset voltage U, and correspondingly outputting a power-down signal.

Wherein, the control circuit 190 is used to perform voltage modulation or operating frequency modulation based on the power-down signal when the output voltage ACON is less than the preset voltage U, that is, when the power-down signal is received, so as to extend the output holding time to the second preset duration.

In some embodiments of the present invention, as shown in FIG. 6 , the power supply circuit 10 may further include: a rectification circuit 160 , a detection sub-circuit 171 , a coupling sub-circuit 172 and a control circuit 190 .

Wherein, the input end of the rectification circuit 160 can be connected to the mains power through the filter circuit 110, as shown in FIG. damage to the rectification circuit 160 and other subsequent circuits; or, the input terminal of the rectification circuit 160 may also be directly connected to the mains, which is not limited herein.

Exemplarily, the rectification circuit 160 can be a full-wave rectification circuit. As shown in FIG. are electrically connected, and the cathodes of the two diodes are electrically connected to the output terminal of the rectifier circuit 160 . The waveform of the AC Vac input to the rectifier circuit 160 is shown in Figure 3. After full-wave rectification by the rectifier circuit 160, the AC Vac' obtained is shown in Figure 8, and the direction of the rectified AC Vac' is positive.

Among them, the rectification circuit 160 transmits the full-wave rectified alternating current Vac' to the detection sub-circuit 171, and when the voltage of the alternating current Vac' decreases from the maximum voltage to the minimum voltage, the energy storage unit in the detection sub-circuit 171 starts to discharge, and detects The output voltage ACON of the subcircuit 171 starts to decrease, and the detection subcircuit 171 can supply power to the control system 20 and the power system 30 at the same time. When the output voltage ACON of the detection sub-circuit 171 drops to be greater than or equal to the preset voltage U, the required duration is longer than the first preset duration, for example, the first preset duration may be the time (20 ms) stipulated by the relevant national standards. When the first preset duration is exceeded, the output voltage ACON of the detection subcircuit 171 may drop to less than the preset voltage U, and it is determined that an AC power failure occurs; at this time, the detection subcircuit 171 transmits a signal to the coupling subcircuit; at the same time, the detection subcircuit The 171 can output the energy stored by itself to the control system 20 to continuously supply power to the control system 20 .

Correspondingly, the coupling subcircuit 172 can receive the output voltage ACON of the detection subcircuit 171, and when the received output voltage ACON is lower than the preset voltage U, that is, when an AC power failure occurs, the coupling subcircuit 172 outputs a power-off signal.

In some embodiments of the present invention, the control terminal of the control circuit 190 can be electrically connected to the output terminal of the detection sub-circuit 171, the control circuit 190 is controlled by the output voltage ACON of the detection sub-circuit 171, and when the output voltage ACON is less than the preset voltage U , that is, when an AC power failure occurs, voltage modulation or operating frequency modulation is performed; at this time, the power supply circuit 10 will continue to supply power to the control system 20 to prolong the output holding time.

In the embodiment of the present invention, the power supply circuit 10 includes a detection subcircuit 171, a coupling subcircuit 172, and a control circuit 190. The output terminal of the detection subcircuit 171 is electrically connected to the input terminal of the coupling subcircuit 172 and the control terminal of the control circuit 190. The control circuit The output end of 190 is electrically connected to the control system 20, and the detection sub-circuit 171 can maintain the output voltage of the detection sub-circuit 171 greater than or equal to the preset voltage within the first preset time period when the voltage of the full-wave rectified alternating current drops, And supply power to the control system 20 when the output voltage is lower than the preset voltage, the coupling sub-circuit 172 can output a power-down signal when the output voltage is lower than the preset voltage, and the control circuit 190 can receive when the output voltage is lower than the preset voltage When the power-off signal is received, voltage modulation or operating frequency modulation is performed to prolong the output hold time, which is beneficial to meet the power-off protection requirements.

In some other embodiments, the control terminal of the control circuit 190 can be electrically connected to the output terminal of the coupling sub-circuit 172, and when the coupling sub-circuit 172 outputs a power-down signal, voltage modulation or operating frequency modulation is performed; at this time, the power supply circuit 10 will Power is continuously supplied to the control system 20 to extend the output hold time.

In some other embodiments, when the control circuit 190 receives the power-off signal, it can also control to shut down the power system 30, that is, the control circuit 190 can shut down the power system when the AC power is off, so that the power circuit 10 can supply power to the control system 20 at all times, instead of supplying power to the power system 30, so as to prevent the power system 30 from consuming the electric energy stored in the power supply circuit 10, and can provide enough electric energy for the control system 20 to complete the power-off protection; The circuit 10 is provided with a capacitor with a large capacity, which can avoid device start-up failure caused by a large capacitor, so that both the timeliness of power-down protection and the stability of device start-up can be taken into account.

In some embodiments of the present invention, the first preset duration in the above embodiments is greater than or equal to the valley duration of the full-wave rectified alternating current.

Exemplarily, the first preset duration may be greater than or equal to the valley duration of Vac', that is, when the alternating current Vac' is in the valley period, the output voltage ACON of the detection sub-circuit 171 has not decreased to less than the preset voltage U, The alternating current Vac' switches to the peak period and starts to charge the detection sub-circuit 171, so that the output voltage ACON of the detection sub-circuit 171 starts to rise. In this way, false detection of AC power failure caused by the valley of the alternating current can be avoided.

Exemplarily, as shown in FIG. 8, during the periods 0-t1, t2-t3, and t4-t5, the alternating current Vac' is a valley period, and the detection subcircuit 171 is in a discharging state. With the discharge of electricity, the detection subcircuit 171 The output voltage ACON is in a falling state, but the output voltage ACON is still greater than or equal to the preset voltage U, so the output voltage ACOFF of the coupling sub-circuit 172 is maintained at a high level. During the periods t1-t2 and t3-t4, the alternating current Vac' changes from a valley period to a peak period, the detection subcircuit 171 switches from a discharge state to a charge state, and the output voltage ACON of the detection subcircuit 171 gradually increases until it is in a stable state, and the coupling The output voltage ACOFF of the sub-circuit 172 is still maintained at a high level, so that the coupling sub-circuit 172 will not output the power-off signal when the AC Vac′ is in a valley period. AC power failure occurs at time t6, and t6-t7 is the first preset duration. During the period t6-t7, the output voltage ACON of the detection sub-circuit 171 is in a falling state, but the output voltage ACON of the detection sub-circuit 171 is still greater than or equal to The preset voltage U, so the output voltage ACOFF of the coupling sub-circuit 172 is maintained at a high level. At time t7, the output voltage ACON of the detection subcircuit 171 is lower than the preset voltage U, the output voltage ACOFF of the coupling subcircuit 172 is switched from high level to low level, and a power-off signal is output.

At this time, the control circuit 190 performs voltage modulation and operating frequency modulation based on the power-down signal to prolong the holding time of the voltage output to the control system 20, that is, the input voltage Vct of the control system 20 is continuously at a high level, that is, continues to provide 20 provides electric energy, so that the control system 20 has enough time to perform power-down protection actions.

At the same time, the control circuit 190 can also shut down the power system 30 under the action of the power-down signal, and then the input voltage Vpo of the power system 30 is converted from a high level to a low level, and no longer consumes the power supply circuit 10 (for example, the detection The electric energy stored in the sub-circuit 171 or other energy storage capacitors) is beneficial to further prolonging the holding time of the voltage output to the control system 20, so that the control system 20 has enough time to perform power-down protection action.

In the embodiment of the present invention, by setting the first preset duration to be greater than or equal to the valley duration of the full-wave rectified AC, false detection of AC power failure caused by the valley of the AC power can be avoided, thereby improving the accuracy of AC power failure detection.

In some embodiments of the present invention, FIG. 9 is a schematic structural diagram of a coupling sub-circuit according to an exemplary embodiment of the present invention. As shown in FIG. 9 , the coupling sub-circuit 172 includes: an optocoupler OC, a first resistor R1 , a second resistor R2 , a third resistor R3 and a first capacitor C1 .

Wherein, the first end of the optocoupler OC is electrically connected to the high-level Vcc through the first resistor R1, the second end of the optocoupler OC is electrically connected to the output end of the detection sub-circuit 171, and the third end of the optocoupler OC The second resistor R2 is electrically connected to the output terminal of the power supply circuit 10, the fourth terminal of the photocoupler OC is electrically connected to the first terminal of the third resistor R3 and the first terminal of the first capacitor C1, and the second terminal of the third resistor R3 Both end and the second end of the first capacitor C1 are grounded.

Exemplarily, as shown in FIG. 9, the first terminal and the second terminal of the photocoupler OC are electrically connected to the anode and cathode of the light-emitting diode N respectively, and the third terminal and the fourth terminal of the photocoupler OC are respectively electrically connected to the phototransistor both ends of the T. When the output voltage ACON of the detection sub-circuit is less than the preset voltage U, the first terminal and the second terminal of the photocoupler OC are disconnected, that is, the light-emitting diode N does not emit light, and the phototransistor T is in the disconnected state, that is, the photocoupler The third terminal and the fourth terminal of OC are disconnected. In this way, when the fourth terminal of the optocoupler OC is at low level, the output voltage ACOFF of the coupling sub-circuit 172 is at low level, that is, a power-off signal is output. When the output voltage ACON of the detection sub-circuit is greater than or equal to the preset voltage U, the first terminal and the second terminal of the photocoupler OC are turned on, that is, the light-emitting diode N emits light, and the phototransistor T is in the conduction state, that is, the photocoupler The third terminal and the fourth terminal of the device OC are turned on. In this way, when the fourth terminal of the optocoupler OC is at a high level, the output voltage ACOFF of the coupling sub-circuit 172 is at a high level, that is, no power-off signal is output.

In some embodiments of the present invention, FIG. 10 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention. On the basis of the embodiment shown in FIG. 9 , as shown in FIG. 10 , the coupling subcircuit 172 may further include: a first comparator ADC1, the first input terminal of the first comparator ADC1 is electrically connected to the output terminal of the detection subcircuit The second input terminal of the first comparator ADC1 is electrically connected to the preset voltage U, and the output terminal of the first comparator ADC1 can be electrically connected to the first terminal of the optocoupler OC. The first comparator ADC1 is used for comparing the output voltage ACON of the detection sub-circuit with the preset voltage U.

Exemplarily, as shown in FIG. 10, the reference voltage Vref is electrically connected to the second input end of the first comparator ADC1 through the first auxiliary voltage dividing resistor R1', and the second input end of the first comparator ADC1 is also electrically connected to the second input end of the first comparator ADC1. The auxiliary voltage dividing resistor R2', the reference voltage Vref is divided by the first auxiliary voltage dividing resistor R1' and the second auxiliary voltage dividing resistor R2', and the preset voltage U can be input to the second input terminal of the first comparator ADC1. The output voltage ACON of the detection sub-circuit is input to the first input terminal of the first comparator ADC1, and the output terminal of the first comparator ADC1 is electrically connected to the first terminal of the photocoupler OC through the first resistor R1. If the output voltage ACON of the detection sub-circuit is less than the preset voltage U, the first comparator ADC1 outputs a low level, that is, the anode of the light-emitting diode N is very low, and the light-emitting diode N does not emit light, so the third of the photocoupler OC terminal and the fourth terminal are disconnected, the output voltage ACOFF of the coupling sub-circuit 172 is at low level, that is, the power-off signal can be output.

In some embodiments of the present invention, FIG. 11 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention. On the basis of the embodiment shown in FIG. 9, as shown in FIG. 11, the coupling subcircuit 172 may further include: a first comparator ADC1, the first input terminal of the first comparator ADC1 is electrically connected to the output terminal of the detection subcircuit The second input terminal of the first comparator ADC1 is electrically connected to the preset voltage U, and the output terminal of the first comparator ADC1 can be electrically connected to the second terminal of the optocoupler OC. The first comparator ADC1 is used for comparing the output voltage ACON of the detection sub-circuit with the preset voltage U.

Exemplarily, as shown in FIG. 11, the reference voltage Vref is electrically connected to the second input terminal of the first comparator ADC1 through the first auxiliary voltage dividing resistor R1', and the second input terminal of the first comparator ADC1 is also electrically connected to the second input terminal of the first comparator ADC1. The auxiliary voltage dividing resistor R2', the reference voltage Vref is divided by the first auxiliary voltage dividing resistor R1' and the second auxiliary voltage dividing resistor R2', and the preset voltage U can be input to the second input terminal of the first comparator ADC1. The output voltage ACON of the detection sub-circuit is input to the first input terminal of the first comparator ADC1, and the output terminal of the first comparator ADC1 is respectively connected to the control terminal of the transistor T1 and the fourth auxiliary voltage divider through the third auxiliary voltage dividing resistor R3' The first end of the resistor R4' is electrically connected, the first end of the transistor T1 is electrically connected to the second end of the photocoupler OC, and the second end of the transistor T1 is electrically connected to the second end of the fourth auxiliary voltage dividing resistor R4'. If the output voltage ACON of the detection sub-circuit is less than the preset voltage U, the first comparator ADC1 outputs a low level, that is, the control terminal of the triode T1 is at a low level, and the first terminal and the second terminal of the triode T1 are disconnected, so , the two ends of the light emitting diode N are not turned on, so the light emitting diode N does not emit light, and the output voltage ACOFF of the coupling sub-circuit 172 is at a low level, that is, the power-off signal can be output.

In some embodiments of the present invention, FIG. 12 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention. On the basis of the embodiment shown in FIG. 9 , as shown in FIG. 12 , the coupling subcircuit 172 may further include: a first comparator ADC1, the first input terminal of the first comparator ADC1 is electrically connected to the output terminal of the detection subcircuit The second input terminal of the first comparator ADC1 is electrically connected to the preset voltage U, and the output terminal of the first comparator ADC1 can be electrically connected to the second terminal of the optocoupler OC and the first terminal of the optocoupler OC. The first comparator ADC1 is used for comparing the output voltage ACON of the detection sub-circuit with the preset voltage U.

Exemplarily, as shown in FIG. 12, the reference voltage Vref is electrically connected to the second input terminal of the first comparator ADC1 through the first auxiliary voltage dividing resistor R1', and the second input terminal of the first comparator ADC1 is also electrically connected to the second input terminal of the first comparator ADC1. The auxiliary voltage dividing resistor R2', the reference voltage Vref is divided by the first auxiliary voltage dividing resistor R1' and the second auxiliary voltage dividing resistor R2', and the preset voltage U can be input to the second input terminal of the first comparator ADC1. The output voltage ACON of the detection sub-circuit is input to the first input terminal of the first comparator ADC1, the output terminal of the first comparator ADC1 is electrically connected to the first terminal of the photocoupler OC through the diode D1, and the output of the first comparator ADC1 terminal is also electrically connected to the second terminal of the optocoupler OC.

If the output voltage ACON of the detection sub-circuit is lower than the preset voltage U, the first comparator ADC1 outputs a high level, that is, the anode of the diode D1 is a high level. At this time, if the anode voltage of the diode D1 is greater than the cathode voltage and the diode D1 is turned on, the voltage across the light-emitting diode N is the same, that is, the light-emitting diode N does not emit light, the two ends of the phototransistor T are disconnected, and the output voltage of the coupling subcircuit 172 ACOFF is low level, that is, the power-down signal can be output. If the anode voltage of the diode D1 is less than or equal to the cathode voltage, the diode D1 is disconnected, and the voltages at both ends of the light-emitting diode N are at a high level, then the light-emitting diode N does not emit light, and the two ends of the phototransistor T are disconnected, and the coupling sub-circuit 172 The output voltage ACOFF is low level, that is, the power-off signal can be output.

The above-mentioned embodiments all exemplarily show the circuit structure that can be adopted for the coupling sub-circuit to generate the power-down signal when the output voltage ACON of the detection sub-circuit is lower than the preset voltage U.

In some embodiments of the present invention, the circuit structure of the coupling sub-circuit can also be set so that when the output voltage ACON of the detection sub-circuit is greater than the preset voltage U, a power-down signal is generated.

Exemplarily, FIG. 13 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention. As shown in FIG. 13 , if the output voltage ACON of the detection sub-circuit is greater than the preset voltage U, the first comparator ADC1 outputs a high level, that is, the anode of the diode D1 is a high level. At this time, if the anode voltage of the diode D1 is greater than the cathode voltage and the diode D1 is turned on, the voltage across the light-emitting diode N is the same, that is, the light-emitting diode N does not emit light, the two ends of the phototransistor T are disconnected, and the output voltage of the coupling subcircuit 172 ACOFF is low level, that is, the power-down signal can be output. If the anode voltage of the diode D1 is less than or equal to the cathode voltage, the diode D1 is disconnected, and the voltages at both ends of the light-emitting diode N are at high level, then the light-emitting diode N does not emit light, the phototransistor T is disconnected, and the output voltage of the coupling subcircuit 172 ACOFF is low level, that is, the power-down signal can be output. As another example, FIG. 14 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention. As shown in Figure 14, if the output voltage ACON is greater than the preset voltage U, the first comparator ADC1 outputs a high level, and the voltages at both ends of the light-emitting diode N are both high-level, then the light-emitting diode N does not emit light, and the phototransistor T disconnected, the output voltage ACOFF of the coupling sub-circuit 172 is at a low level, that is, the power-down signal can be output.

In some embodiments of the present invention, FIG. 15 is a schematic structural diagram of another coupling sub-circuit according to an exemplary embodiment of the present invention. On the basis of the embodiment shown in FIG. 9 , as shown in FIG. 15 , the coupling subcircuit 172 also includes: a third switch K3; the control terminal of the third switch K3 is electrically connected to the output terminal of the detection subcircuit 171, and the third switch K3 The first end of the first end of the photocoupler OC is electrically connected to the second end of the photocoupler OC, and the second end of the third switch K3 is electrically connected to the equipotential point; the third switch K3 is used to detect when the output voltage ACON of the sub-circuit is less than the preset voltage U, The first terminal and the second terminal of the third switch K3 are disconnected.

Exemplarily, as shown in FIG. 15, the third switch K3 may specifically be an N-type Metal Oxide Semiconductor (MOS) transistor. If the output voltage ACON of the detection sub-circuit is at a low level, the two switches of the third switch K3 If the terminal is disconnected, the two ends of the light-emitting diode N are disconnected, that is, the light-emitting diode N does not emit light. In this way, the two ends of the phototransistor T are disconnected, and the output voltage ACOFF of the coupling sub-circuit 172 is at a low level, that is, the output power-off Signal.

In other implementation manners, the third switch K3 may also use other types of controlled switch tubes, which are not limited herein.

In some embodiments of the present invention, FIG. 16 is a schematic structural diagram of a detection sub-circuit according to an exemplary embodiment of the present invention, showing an optional circuit structure of the detection sub-circuit in the foregoing implementation manner. As shown in Figure 16, the detection sub-circuit 171 includes: a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a Zener diode D2, a fourth switch K4, the fifth switch K5 and the second capacitor C2.

Wherein, the first end of the fourth resistor R4 is electrically connected to the input end of the detection sub-circuit, the control end of the Zener diode D2 is electrically connected to the second end of the fourth resistor R4 and the first end of the fifth resistor R5, and the Zener diode D2 The first end of the sixth resistor R6 is electrically connected to the first end of the fourth switch K4, and the first end of the fourth switch K4 is electrically connected to the first end of the seventh resistor R7 and the first end of the eighth resistor R8. and the control end of the fifth switch K5, the first end of the fifth switch K5 is electrically connected to the first end of the ninth resistor R9, the second end of the sixth resistor R6 and the second end of the fourth switch K4 are both connected to a high level Vcc is electrically connected, the second end of the seventh resistor R7, the second end of the ninth resistor R9, and the first end of the second capacitor C2 are all electrically connected to the output end of the detection sub-circuit, and the second end of the fifth resistor R5, the stable The second terminal of the voltage diode D2, the second terminal of the eighth resistor R8, the second terminal of the fifth switch K5 and the second terminal of the second capacitor C2 are electrically connected to the equipotential point.

Exemplarily, as shown in FIG. 16, the rectified alternating current Vac' is divided by the fourth resistor R4 and the fifth resistor R5 to generate V1, and input to the Zener diode D2. When V1 is higher than the voltage threshold, for example, The voltage threshold can be 2.5V, the Zener diode D2 is turned on, the fourth switch K4 is turned on, the high level Vcc charges the second capacitor C2 through R7, and the output voltage ACON of the detection sub-circuit is higher than the preset voltage U. When V1 is lower than the voltage threshold, the fourth switch K4 is turned off, the fifth switch K5 is turned on, and the second capacitor C2 is discharged through the ninth resistor R9 and the fifth switch K5. The resistance values of the ninth resistor R9 and the seventh resistor R7 are adjusted so that the discharging time of the second capacitor C2 is much longer than the charging time. And the time required for the output voltage ACON of the detection sub-circuit to drop to the preset voltage U is longer than the first preset time length; for example, the first preset time length may be 20 ms as specified in the relevant standard, thereby avoiding that the alternating current is in the trough. The resulting misdetection of AC power failure may also send a power failure signal according to the first preset duration.

In some embodiments of the present invention, FIG. 17 is a schematic structural diagram of another detection sub-circuit according to an exemplary embodiment of the present invention. On the basis of the embodiment shown in FIG. 16, as shown in FIG. 17, the detection sub-circuit 171 includes: a second comparator ADC2, a sixth switch K6, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor R14 and the third capacitor C3.

Wherein, the first end of the tenth resistor R10 is electrically connected to the input end of the detection sub-circuit, and the second end of the tenth resistor R10 is electrically connected to the first input end of the second comparator ADC2 and the first end of the eleventh resistor R11 , the second input end of the second comparator ADC2 is electrically connected to the reference voltage Vref, the output end of the second comparator ADC2 is electrically connected to the control end of the sixth switch K6 and the first end of the twelfth resistor R12, and the sixth switch K6 The first end is electrically connected to the first end of the thirteenth resistor R13, and the second end of the thirteenth resistor R13 is electrically connected to the input end of the coupling circuit, the first end of the fourteenth resistor R14, and the first end of the third capacitor C3 , the second end of the eleventh resistor R11, the second end of the twelfth resistor R12, the second end of the sixth switch K6 and the second end of the third capacitor C3 are electrically connected to the equipotential point, the fourteenth resistor R14 The second end is electrically connected to the reference voltage Vref.

Exemplarily, as shown in FIG. 17, the reference voltage Vref is electrically connected to the sixth auxiliary voltage dividing resistor R6' through the fifth auxiliary voltage dividing resistor R5', and the reference voltage Vref is also connected to the second auxiliary voltage dividing resistor R5' through the fifth auxiliary voltage dividing resistor R5'. The second input end of the comparator ADC2 is electrically connected, and the divided voltage input to the second end of the second comparator ADC2 is the preset voltage U. The alternating current Vac' output by the rectification circuit is divided by the tenth resistor R10 and the eleventh resistor R11 to generate a sampling voltage V1, and V1 is input to the first input terminal of the second comparator ADC2. The second comparator ADC2 can compare V1 with the preset voltage U, and output V2. For example, as shown in FIG. V2 output by the second comparator ADC2 is low level.

V2 controls the turn-on and turn-off of the sixth switch K6. If V2 is low level, the sixth switch K6 is turned off, and the reference voltage Vref charges the third capacitor C3 through the fourteenth resistor R14; if V2 is high level Ping, the sixth switch K6 is turned on, and the third capacitor C3 is discharged through the sixth switch K6 and the thirteenth resistor R13. The resistance of the thirteenth resistor R13 is set to be much larger than the resistance of the fourteenth resistor R14, so that the charging time of the third capacitor C3 is much shorter than the discharging time.

For example, in combination with the coupling sub-circuit 172 shown in FIG. 12 and the detection sub-circuit 171 shown in FIG. 17 , when the rectified alternating current is at the peak period, as shown in FIG. 18 during t1-t2 and t3-t4, V1>U, The output voltage V2 of the second comparator ADC2 is at a low level, the sixth switch K6 is turned off, and the output voltage ACON of the detection sub-circuit 171 is at a high level continuously. The voltage of the first input terminal of the first comparator ADC1 is the output voltage ACON, the voltage of the second terminal of the first comparator ADC1 is the preset voltage U, and ACON>U, the output voltage V3 of the first comparator ADC1 is low level , the photocoupler OC is turned on, and the output voltage ACOFF of the coupling circuit is at a high level. When the rectified alternating current is in the valley periods 0-t1, t2-t3 and t4-t5, V1<U, the output voltage V2 of the second comparator ADC2 is at a high level, the sixth switch K6 is turned on, and the detection subcircuit 171 The output voltage ACON decreases continuously but is greater than the preset voltage U. The voltage of the first input terminal of the first comparator ADC1 is the output voltage ACON, the voltage of the second terminal of the first comparator ADC1 is the preset voltage U, and ACON>U, the output voltage V3 of the first comparator ADC1 is low level , the photocoupler OC is turned on, and the output voltage ACOFF of the coupling circuit is continuously at a high level. After the AC power is cut off, that is, the sorted AC power is in the t6-t7 period, V1<U, the output voltage V2 of the second comparator ADC2 is at a high level, the sixth switch K6 is turned on, and the output voltage ACON of the detection sub-circuit 171 is Continue to decrease but be greater than the preset voltage U, until after t7, the output voltage ACON is less than the preset voltage U. At this time, the output voltage V3 of the first comparator ADC1 is converted from low level to high level, the photocoupler is turned off, and the output voltage ACOFF of the coupling circuit is converted from high level to low level, that is, the power-off signal is output .

The coupling sub-circuit and the detection sub-circuit in the detection circuit are exemplarily described above with reference to FIGS. 9-18 . The working frequency modulation and voltage modulation of the control circuit are respectively exemplified below in conjunction with FIG. 19 and FIG. 21 .

In some embodiments of the present invention, the control circuit 190 includes a power controller; the power controller sets the power-down working mode; in the power-down working mode, the operating frequency of the resonant loop corresponding to the power supply circuit is a preset value; the power control The device is used to switch to the power-down working mode based on the power-down signal to realize working frequency modulation.

In the embodiments of the present disclosure, the working mode is mainly determined by the working frequency, and may include a normal working mode and a power-down working mode. Among them, in the normal working mode, the working frequency changes with the change of the input voltage; in the power-down working mode, the working frequency is a preset value, that is, the working frequency in the power-down working mode no longer changes with the change of the input voltage , but a fixed value. On this basis, the switching of the working mode is realized based on the power-down signal. Specifically, the power controller can switch the working mode based on the power-down signal, such as switching the normal working mode to the power-down working mode, so that the working frequency becomes a preset value, that is, the frequency no longer changes; at this time, The gain is also fixed so that as the input voltage decreases, the output voltage also decreases. Since there is no protection due to excessive gain, the power circuit can continue to work under the condition of low input voltage, and the energy stored in the input electrolytic capacitor in the power circuit can be transferred to the output to the maximum extent, and the output time can be extended.

Specifically, it is assumed that the power supply circuit is an LLC circuit as an example.

It can be known from the working principle of LLC:

Among them, Vo represents the output voltage, V _IN represents the input voltage, and G represents the LLC resonant loop gain. When the AC power fails, the input voltage decreases. From the above formula, it can be known that the LLC needs to increase the gain in order to maintain the output voltage.

Exemplarily, FIG. 19 is an LLC gain curve. From the gain curve shown in FIG. 19, it can be seen that: the LLC circuit has a maximum gain M ^m , and when the required gain exceeds the maximum gain, the LLC system will stop working for protection; and When the gain changes from a smaller gain Mmin to a larger gain Mmax, as the gain increases, the operating frequency of the LLC system will decrease.

Based on this, the embodiment of the present invention provides to prolong the output holding time by setting the working frequency. Specifically, in combination with the above, a detection circuit is added to the conventional LLC power supply circuit. When the AC power failure is detected, the detection circuit transmits the power failure information to the control circuit, such as a power controller, which may specifically be an LLC controller; the corresponding , the LLC controller switches the working mode based on the power-down signal, and switches the working mode to the power-down working mode. In the power-down working mode, the working frequency is fixed, and the working frequency does not decrease as the input voltage decreases.

At the same time, from the gain curve shown in Figure 19 and the working principle of LLC, it can be seen that when the operating frequency remains unchanged, the gain remains unchanged; therefore, when the input voltage decreases, the output voltage also decreases.

Since the LLC system no longer has over-gain protection and stops working, the LLC system can continue to work under the condition of low input voltage, and the energy stored in the LLC input electrolytic capacitor can be transferred to the output to the maximum extent.

In the embodiment of the present invention, the detection circuit is used to detect the AC power failure, and the power failure signal is output to the control circuit, and the control circuit is used to change the working mode of the power supply circuit, without increasing the AC power failure signal line and without increasing the output capacitance. Prolonging the output time and maximizing the use of the charge in the PFC output electrolytic capacitor is conducive to meeting the power-down protection requirements.

In some embodiments of the present invention, FIG. 20 is a schematic structural diagram of another power supply circuit according to an exemplary embodiment of the present invention. As shown in Figure 20, the power supply circuit 10 may also include: a filter circuit 110, a power frequency rectifier circuit 120, a PFC circuit 130, a DC conversion circuit 140, and an output rectifier circuit 150 electrically connected in sequence; the filter circuit 110 is used to filter out The clutter electric signal in the alternating current; the power frequency rectification circuit 120 is used to rectify the alternating current after filtering the clutter electric signal to obtain direct current; the PFC circuit 130 is used to control the waveform synchronization of the direct current and the alternating current; the direct current conversion circuit 140 It is used to step down the synchronized direct current; the output rectifier circuit 150 is used to rectify the stepped down direct current and output the voltage to the control system; the detection circuit 170 is used to detect the alternating current after filtering out the clutter signal, the power supply The controller is built into the DC conversion circuit 140 .

In the embodiment of the present disclosure, the power supply circuit 10 includes two outputs, respectively connected to the control system 20 and the power system 30; correspondingly, the DC conversion circuit 140 includes a first DC/DC converter 141 and a second DC/DC converter 142, The output rectification circuit 150 includes a first output rectification circuit 151 and a second output rectification circuit 152; the control system 20 is connected to the PFC circuit 130 via the first output rectification circuit 151 and the first DC/DC converter, and the power system 30 is connected to the PFC circuit 130 via the second output rectification circuit 151; The rectification circuit 152 and the second DC/DC converter 142 are connected to the PFC circuit 130 . Wherein, one end of the detection circuit 10 is connected between the filter circuit 110 and the power frequency rectification circuit 120, and the other end is connected between the PFC circuit 130 and the first DC/DC converter 141, and the power controller is built in the first DC/DC Converter 141. The detection circuit 110 detects the AC power, and after detecting the AC power failure, transmits the power-down signal to the first DC/DC converter 141; correspondingly, the power controller in the first DC/DC converter 141 based on the power-down The signal switches the working mode of the power supply circuit 10 to the power-down working mode, and the corresponding working frequency is set to a preset value, so as to realize frequency modulation and prolong the output time, which is beneficial to meet power-down protection requirements.

In some embodiments of the present invention, FIG. 21 is a schematic structural diagram of a control circuit according to an exemplary embodiment of the present invention. As shown in Figure 21, the control circuit 190 also includes a first switch K1 and a second switch K2: the control terminal of the first switch K1 is connected to the control terminal of the control circuit 190, the input terminal of the first switch K1 is connected to the standby signal STB, and connected to The control end of the second switch K2, the input end of the second switch K2 is connected to the output end of the control circuit 190, the output end of the first switch K1 and the output end of the second switch K2 are both grounded; the first switch K1 is used to The signal ACOFF is turned on, and the standby signal STB is pulled down; the second switch K2 is turned on based on the pulled-down standby signal STB, and the voltage of the output terminal of the control circuit 190 is pulled down to the target voltage to realize voltage modulation.

Specifically, in the power supply circuit, a high-level standby signal STB is input when the electrical equipment is working normally; when the electrical equipment is in standby, in order to reduce standby power consumption, the main control board pulls the standby signal STB low to turn the power supply circuit The output voltage Vout is adjusted down. Exemplarily, taking a TV as an example, the output voltage Vout is generally adjusted from 12V to 9V. Based on this, in the embodiment of the present invention, the control circuit uses the power-off signal ACOFF corresponding to the AC outlet to pull down the standby signal STB of the main control board, and the main control board can judge whether the AC power is off through the level conversion of the standby signal STB.

As shown in Figure 21, the control circuit 190 in the power supply circuit includes a first switch K1 and a second switch K2. When the AC power fails, the power-off signal ACOFF switches to a low-level signal, and the first switch K1 is turned on at this time. , the standby signal STB is discharged to the ground, and the level of the standby signal STB is pulled down; furthermore, the signal at the control terminal of the second switch K2 is converted into a low-level signal, the second switch K2 is turned on, and the output voltage Vout passes through the second switch K2 Discharge to the ground, the output voltage Vout is pulled down, and the main control board can judge the AC power failure. At this time, although the input voltage of the power circuit decreases due to the AC power failure, the output voltage also decreases, so that the power circuit can continue to work for a period of time, so that the output holding time can be extended, so that the output time can meet the power-down protection of the main control board demand.

In some embodiments of the present invention, referring to FIG. 21 , the control circuit 190 further includes a first voltage dividing resistor R21, a second voltage dividing resistor R22, a third voltage dividing resistor R23, a fourth voltage dividing resistor R24 and a fifth voltage dividing resistor R24. The voltage dividing resistor R25; the first voltage dividing resistor R21 is connected in series between the control terminal of the first switch K1 and the control terminal of the control circuit 190, and the second voltage dividing resistor R22 is connected in series between the control terminal of the first switch K1 and the ground; The third voltage dividing resistor R23 is connected in series between the input terminal of the first switch K1 and the control terminal of the second switch K2, the fourth voltage dividing resistor R24 is connected in series between the control terminal of the second switch K2 and the ground; the fifth voltage dividing The resistor R25 is connected in series between the input terminal of the second switch K2 and the output terminal of the control circuit 190 .

Specifically, compared with the power feedback circuit in the related art, the embodiment of the present disclosure adds the first voltage dividing resistor R21, the second voltage dividing resistor R22 and the first switch K1; when the AC power is turned off, this part of the circuit The standby signal STB is pulled low, and then the output signal Vout of the main control board is pulled low. As the input voltage is reduced, the output voltage is also reduced, so the power supply circuit can continue to work for a period of time, that is, the output holding time is extended, which is beneficial to meet the power-down protection requirements.

It should be noted that the feedback signal FB, photocoupler, resistors R26, R27, R29, R30, and capacitors C4 and C5 shown in Fig. 21 are all optional settings in the power supply feedback circuit. In other embodiments, the power supply The feedback circuit may also include other circuit components, which are not limited here.

The relevant circuits and working principles of the control circuit for voltage modulation and working frequency modulation are exemplarily described above, and the optional circuit structure for the control circuit to realize the shutdown power system will be described below in conjunction with FIG. 22 and FIG. 23 .

In some embodiments of the present invention, FIG. 22 is a schematic structural diagram of another control circuit according to an exemplary embodiment of the present invention. As shown in FIG. 22 , the control circuit 190 includes: a seventh switch K7, a seventh switch K7 The control terminal of the seventh switch K7 is electrically connected to the output terminal of the detection sub-circuit, the first terminal of the seventh switch K7 is electrically connected to the enabling terminal EN of the power system, and the second terminal of the seventh switch K7 is electrically connected to the equipotential point.

The control circuit 190 is configured to turn on the first terminal and the second terminal of the seventh switch K7 when the output voltage ACON is less than the preset voltage U, and output a non-enabling signal to the enabling terminal EN of the power system; when the output voltage is greater than When ACON is equal to or equal to the preset voltage U, the first terminal and the second terminal of the seventh switch K7 are disconnected, and an enabling signal is output to the enabling terminal EN of the power system.

Exemplarily, as shown in FIG. 22, when the output voltage ACON is greater than or equal to the preset voltage U, that is, when the AC power is off, the output voltage ACON of the detection sub-circuit is at a low level, and the seventh switch K7 is a P-type MOS transistor , then the first end and the second end of the seventh switch K7 are turned on, and the enabling end EN of the power system can be pulled down to a low level, so that the enabling end EN receives a non-enabling signal, and the power system is turned off . When the output voltage ACON is greater than or equal to the preset voltage U, that is, when the AC power failure does not occur, the output voltage ACON of the detection sub-circuit is at a high level, and the first terminal and the second terminal of the seventh switch K7 are disconnected. Change the level of the enabling terminal EN of the power system, so that the enabling terminal EN receives the enabling signal, and then turns on the power system.

In other implementation manners, the seventh switch K7 may be an N-type MOS transistor, and when the AC power is off, the output voltage ACON of the detection sub-circuit is at a high level.

In some embodiments of the present invention, FIG. 23 is a schematic structural diagram of another control circuit according to an exemplary embodiment of the present invention. As shown in FIG. 23 , the control circuit 190 includes: a seventh switch K7, a seventh switch K7 The control end of the seventh switch K7 is electrically connected to the output end of the coupling sub-circuit, the first end of the seventh switch K7 is electrically connected to the enabling end EN of the power system, and the second end of the seventh switch K7 is electrically connected to the equipotential point.

The control circuit 190 is configured to turn on the first terminal and the second terminal of the seventh switch K7 when outputting a power-down signal, and output a non-enabling signal to the enabling terminal EN of the power system; when the power-down signal is not output, The first terminal and the second terminal of the seventh switch K7 are disconnected, and an enabling signal is output to the enabling terminal EN of the power system.

Exemplarily, as shown in FIG. 23, the seventh switch K7 is a P-type MOS transistor. When the AC power is off, the output voltage ACOFF of the coupling subcircuit is at a low level, that is, a power-off signal is output, and the seventh switch K7 The first end and the second end are turned on, and the enabling end EN of the power system can be pulled down to a low level. In this way, when the enabling end EN receives a non-enabling signal, the power system is turned off. When the AC power failure does not occur, the output voltage ACOFF of the coupling sub-circuit is at a high level, that is, the power-off signal is not output, then the first terminal and the second terminal of the seventh switch K7 are disconnected, and the enabling of the power system is not changed. The level of the terminal EN, so that the enabling terminal EN receives the enabling signal, and the power system is turned on.

In other implementation manners, the seventh switch K7 may be an N-type MOS transistor, and when the AC power is off, the output voltage ACOFF of the coupling sub-circuit is at a high level.

The present invention also provides an electrical device. FIG. 24 is a schematic structural diagram of an electrical device according to an exemplary embodiment of the present invention. As shown in FIG. 24 , the electrical device may include: a display screen 40, a power system 30, Control system 20 and power supply circuit 10 .

Wherein, the power system 30 is electrically connected to the display screen 40 , the control system 20 is electrically connected to the power system 30 , and the output terminal of the power supply circuit 10 is electrically connected to the power system 30 and the control system 20 . The power supply circuit 10 can convert the alternating current of the commercial power into direct current, and supply power to the control system 20 and the power system 30 respectively.

This embodiment only exemplifies a scenario where any of the above power circuits is applied to an electrical device. In the scenario of an electrical device, the power system can be understood as a drive circuit of the electrical device, and the control system can be understood as a signal processing circuit of the electrical device. In practical applications, the power supply circuit can also be applied to equipment such as refrigerators, washing machines, and air conditioners, which is not specifically limited in this embodiment of the present invention.

Exemplarily, the power circuit is applied to a washing machine, the power system is the motor circuit, the control system is the motor control circuit, the power circuit can provide power to the motor control circuit and the motor circuit, and can shut down the motor when the AC power is off , so that the power supply circuit does not supply power to the motor circuit, but continues to supply power to the motor control circuit, and through voltage modulation and operating frequency modulation, the output holding time is extended to complete the power-down protection action.

As another example, the power circuit is applied to the air conditioner, the power system is the air conditioner compressor circuit, the control system is the control circuit of the air conditioner compressor, the power supply circuit can provide power to the air conditioner compressor control circuit and the air conditioner compressor circuit, and When the AC power is off, the air-conditioning compressor circuit can be turned off, so that the power supply circuit will not supply power to the air-conditioning compressor circuit, but continue to supply power to the air-conditioning compressor control circuit, and through voltage modulation and operating frequency modulation, the output retention time can be extended to ensure Complete the power-down protection action.

In the embodiment of the present invention, the electrical equipment includes a display screen, a power system, a digital processing circuit, and a power supply circuit. The power system is electrically connected to the display screen. The power system can drive the display screen to display images. system, the power supply circuit can convert alternating current into direct current, and supply power to the power system and control system; the power supply circuit includes: a detection circuit and a control circuit; and the input end of the detection circuit is connected to alternating current, and the output end of the detection circuit is connected to The control terminal of the control circuit, the output terminal of the control circuit is connected to the control system of the electrical equipment; the detection circuit is used to output a power-down signal after detecting the first preset duration of the AC power failure; the The control circuit is used to perform voltage modulation or operating frequency modulation based on the power-off signal, so that the duration of the voltage transmitted to the control system is extended to a second preset duration, so that the power supply circuit can use detection for AC power-off The circuit is used for detection, and the control circuit is based on voltage modulation or working frequency modulation to extend the output holding time. Without increasing the AC power-off signal line and the structure of the output capacitor, the problem of short output holding time when the AC power is off is solved. , which is conducive to meeting the power-down protection requirements.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

For convenience of explanation, the above description has been made in conjunction with specific implementation manners. However, the above exemplary discussion is not intended to be exhaustive or to limit the implementations to the precise forms disclosed above. Many modifications and variations are possible in light of the above teachings. The selection and description of the above embodiments are to better explain the principles and practical applications, so that those skilled in the art can better use the embodiments and various modified embodiments suitable for specific use considerations.

Claims (10)

1. A power supply circuit, comprising: a detection circuit and a control circuit;

the input end of the detection circuit is connected with alternating current, the output end of the detection circuit is connected with the control end of the control circuit, and the output end of the control circuit is connected with a control system of the electric equipment;

the detection circuit is used for outputting a power failure signal after detecting a first preset duration of the power failure of the alternating current;

the control circuit is used for carrying out voltage modulation or working frequency modulation based on the power failure signal, so that the holding time of the voltage transmitted to the control system is prolonged to a second preset time.

2. The power supply circuit of claim 1, wherein the control circuit comprises a power supply controller;

the power supply controller is set in a power-down working mode; in the power-down working mode, the working frequency of a resonance loop corresponding to the power circuit is a preset value;

and the power supply controller is used for switching to the power-down working mode based on the power-down signal to realize working frequency modulation.

3. The power supply circuit according to claim 2, further comprising: the power frequency rectifier circuit is connected with the filter circuit, the PFC circuit, the direct current conversion circuit and the output rectifier circuit in sequence;

the filter circuit is used for filtering clutter electric signals in the alternating current;

the power frequency rectifying circuit is used for rectifying the alternating current after the clutter electrical signals are filtered out to obtain direct current;

the PFC circuit is used for controlling the waveform of the direct current to be synchronous with the waveform of the alternating current;

the direct current conversion circuit is used for carrying out voltage reduction treatment on the synchronized direct current;

the output rectifying circuit is used for rectifying the direct current after voltage reduction and outputting voltage to the control system;

the detection circuit is used for detecting the alternating current after the clutter signals are filtered, and the power controller is arranged in the direct current conversion circuit.

4. The power supply circuit of claim 1, wherein the control circuit further comprises a first switch and a second switch:

the control end of the first switch is connected with the control end of the control circuit, the input end of the first switch is connected with a standby signal and the control end of the second switch, the input end of the second switch is connected with the output end of the control circuit, and the output end of the first switch and the output end of the second switch are both grounded;

the first switch is used for pulling down the standby signal based on the conduction of the power-down signal;

and the second switch is switched on based on the pulled-down standby signal, and the voltage of the output end of the control circuit is pulled down to the target voltage, so that voltage modulation is realized.

5. The power supply circuit according to claim 4, wherein the control circuit further comprises a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a fourth voltage-dividing resistor, and a fifth voltage-dividing resistor;

the first voltage-dividing resistor is connected in series between the control end of the first switch and the control end of the control circuit, and the second voltage-dividing resistor is connected in series between the control end of the first switch and the ground;

the third voltage dividing resistor is connected between the input end of the first switch and the control end of the second switch in series, and the fourth voltage dividing resistor is connected between the control end of the second switch and the ground in series;

the fifth voltage-dividing resistor is connected in series between the input end of the second switch and the output end of the control circuit.

6. The power supply circuit according to any one of claims 1 to 5, wherein the detection circuit comprises a detection sub-circuit and a coupling sub-circuit;

the output end of the detection sub-circuit is electrically connected with the input end of the coupling sub-circuit, and the output end of the coupling sub-circuit is connected with the control end of the control circuit;

the detection sub-circuit is used for maintaining the output voltage of the detection sub-circuit to be greater than or equal to a preset voltage within a first preset time when the voltage of the full-wave rectified alternating current is reduced;

the coupling sub-circuit is used for outputting the power-down signal when the output voltage of the detection sub-circuit is smaller than a preset voltage;

the first preset time length is greater than or equal to the wave trough time length of the alternating current after full-wave rectification.

7. The power supply circuit of claim 6, wherein the coupling sub-circuit comprises: the circuit comprises a photoelectric coupler, a first resistor, a second resistor, a third resistor and a first capacitor;

the first end of the photoelectric coupler is electrically connected with a high level through a first resistor, the second end of the photoelectric coupler is electrically connected with the output end of the detection sub-circuit, the third end of the photoelectric coupler is electrically connected with the output end of the power circuit through a second resistor, the fourth end of the photoelectric coupler is electrically connected with the first end of the third resistor and the first end of the first capacitor, and the second end of the third resistor and the second end of the first capacitor are both grounded;

and the photoelectric coupler is used for disconnecting the third end and the fourth end of the photoelectric coupler when the output voltage is less than the preset voltage.

8. The power supply circuit of claim 7, wherein the coupling sub-circuit further comprises: a first comparator;

a first input end of the first comparator is electrically connected with an output end of the detection sub-circuit, a second input end of the first comparator is electrically connected with the preset voltage, and an output end of the first comparator is electrically connected with a first end of the photoelectric coupler and/or a second end of the photoelectric coupler;

the first comparator is used for comparing the output voltage with the preset voltage;

alternatively, the coupling sub-circuit further comprises: a third switch;

a control end of the third switch is electrically connected with an output end of the detection sub-circuit, a first end of the third switch is electrically connected with a second end of the photoelectric coupler, and a second end of the third switch is electrically connected with an isoelectric point;

the third switch is used for disconnecting the first end and the second end of the third switch when the output voltage is smaller than the preset voltage.

9. The power supply circuit of claim 6, wherein the detection subcircuit comprises: the fourth resistor, the fifth resistor, the sixth resistor, the seventh resistor, the eighth resistor, the ninth resistor, the voltage stabilizing diode, the fourth switch, the fifth switch and the second capacitor;

a first end of the fourth resistor is electrically connected to an input end of the detection sub-circuit, a control end of the zener diode is electrically connected to a second end of the fourth resistor and a first end of the fifth resistor, a first end of the zener diode is electrically connected to a first end of the sixth resistor and a control end of the fourth switch, a first end of the fourth switch is electrically connected to a first end of the seventh resistor, a first end of the eighth resistor and a control end of the fifth switch, a first end of the fifth switch is electrically connected to a first end of the ninth resistor, a second end of the sixth resistor and a second end of the fourth switch are all electrically connected to a high level, a second end of the seventh resistor, a second end of the ninth resistor and a first end of the second capacitor are all electrically connected to an output end of the detection sub-circuit, and a second end of the fifth resistor, a second end of the zener diode, a second end of the eighth resistor, a second end of the fifth switch and a second end of the second capacitor are electrically connected to an equipotential point;

alternatively, the detection sub-circuit comprises: the circuit comprises a second comparator, a sixth switch, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a third capacitor;

a first end of the tenth resistor is electrically connected to the input end of the detection sub-circuit, a second end of the tenth resistor is electrically connected to the first input end of the second comparator and the first end of the eleventh resistor, a second input end of the second comparator is electrically connected to a reference voltage, an output end of the second comparator is electrically connected to the control end of the sixth switch and the first end of the twelfth resistor, the first end of the sixth switch is electrically connected to the first end of the thirteenth resistor, a second end of the thirteenth resistor is electrically connected to the input end of the coupling circuit, the first end of the fourteenth resistor and the first end of the third capacitor, a second end of the eleventh resistor, the second end of the twelfth resistor, the second end of the sixth switch and the second end of the third capacitor are electrically connected to an equipotential point, and a second end of the fourteenth resistor is electrically connected to the reference voltage.

10. An electrical device, comprising:

a display screen;

the power system is electrically connected with the display screen and is used for driving the display screen to display pictures;

a control system electrically connected with the power system;

the power supply circuit of any one of claims 1-9, an output of the power supply circuit being coupled to the control system, the power supply circuit being configured to supply power to the control system.

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