CN106813269B - Electromagnetic heating equipment - Google Patents

Abstract

The invention relates to the technical field of heating of induction cookers, and provides an electromagnetic heating device, which comprises: the device comprises an electromagnetic heating unit, an infrared heating unit and an MCU. The MCU is connected with the electromagnetic heating unit and the infrared heating unit and is used for controlling the electromagnetic heating unit and the infrared heating unit to heat independently or simultaneously. The electromagnetic heating equipment comprises the electromagnetic heating unit and the infrared heating unit, so that heating of heating appliances made of different materials can be realized, and the application range is not limited. Furthermore, since the infrared heating unit is included, the maximum heating power thereof is not limited by the maximum heating power of the coil disk.

Description

An electromagnetic heating device

technical field

The invention relates to the technical field of induction cooker heating, in particular to an electromagnetic heating device.

Background technique

The current induction cooker generally only has a coil plate, so it can only heat ferromagnetic cooking utensils, but cannot heat non-ferromagnetic cooking utensils, and the types of cooking utensils used are limited. In addition, for ferromagnetic cooking appliances, the maximum heating power is also limited by the maximum heating power of the coil disk.

SUMMARY OF THE INVENTION

(1) Technical problems to be solved

The technical problem to be solved by the present invention is to provide an electromagnetic heating device, which includes not only an electromagnetic heating unit but also an infrared heating unit, so as to avoid the limitation of the application of the induction cooker by a single electromagnetic heating method.

(2) Technical solutions

In order to solve the above-mentioned technical problems, the present invention provides an electromagnetic heating device, comprising:

Electromagnetic heating unit, infrared heating unit and MCU,

The MCU is connected with the electromagnetic heating unit and the infrared heating unit, so as to control the electromagnetic heating unit and the infrared heating unit to be heated individually or simultaneously.

Preferably, the MCU includes a pot detection module and a power distribution module;

When the pot detection module does not detect the existence of the cooking utensil, the power distribution module stops distributing the heating power to the infrared heating unit and the electromagnetic heating unit to be zero; when the pot detection module detects the cooking utensil When present, the power distribution module distributes heating power to at least one of the infrared heating unit and the electromagnetic heating unit.

Preferably, the electromagnetic heating unit includes:

A resonant circuit, the resonant circuit includes a switching element, a resonant capacitor and a resonant inductance, the resonant capacitor and the resonant inductance are connected in parallel, and one of the common connection ends of the resonant capacitor and the resonant inductance is connected to the rectified commercial power, and the other common The connection terminal is connected with the collector of the switching element;

an electromagnetic drive circuit, one end of the drive circuit is connected to the electromagnetic power adjustment module in the MCU, and the other end is connected to the base of the switching element;

a resonance synchronization detection circuit, one end is connected to the collector of the switching element to detect the voltage of the collector of the switching element, and the other end is connected to the MCU;

After the MCU sends a pot detection pulse to the electromagnetic drive circuit, the pot detection module determines whether the cooking utensil exists according to whether the number of times of voltage inversion output by the resonance synchronization detection circuit is lower than a predetermined number of times.

Preferably, the MCU includes a material detection module and a power distribution module, when the material detection module detects a ferromagnetic cooking utensil, the power distribution module switches to start the electromagnetic heating unit and/or the infrared heating unit The heating unit heats the cooking utensil; when the material detection module detects a non-ferromagnetic cooking utensil, the power distribution module switches to activate the infrared heating unit to heat the cooking utensil.

Preferably, the MCU includes a heating switching reminder module, and the heating switching reminder module reminds the user to select a corresponding heating unit for heating according to the material of the cooking utensil detected by the material detection module.

Preferably, the electromagnetic heating unit includes:

A resonant circuit, the resonant circuit includes a switching element, a resonant capacitor and a resonant inductance, the resonant capacitor and the resonant inductance are connected in parallel, and one of the common connection ends of the resonant capacitor and the resonant inductance is connected to the rectified commercial power, and the other common The connection terminal is connected with the collector of the switching element;

an electromagnetic drive circuit, one end of the drive circuit is connected to the MCU, and the other end is connected to the base of the switching element;

a resonance synchronization detection circuit, one end is connected to the collector of the switching element to detect the voltage of the collector of the switching element, and the other end is connected to the MCU;

After the MCU sends the pot detection pulse to the electromagnetic drive circuit, the material detection module determines the material of the cooking utensil by detecting the interval time between adjacent inversion voltages output by the resonance synchronization detection circuit.

Preferably, the infrared heating unit includes an infrared heating circuit and an infrared driving circuit; the infrared heating circuit has an infrared heating film connected between the mains zero line and the live line, and one end of the infrared driving circuit is connected to the infrared heating film. Between the heating film and the commercial power, the other end of the infrared drive circuit is connected to the infrared power adjustment module in the MCU, and the infrared power adjustment module inputs a second input to the infrared drive circuit according to the assigned heating power value. PWM signal with a predetermined duty cycle. Preferably, the electromagnetic heating unit further includes a zero-crossing detection circuit, one end of the zero-crossing detection circuit is connected to the rectified commercial power to detect the zero-crossing signal of the commercial power, and the other end is connected to the MCU;

The MCU inputs the PWM signal of the predetermined duty cycle to the infrared driving circuit at a predetermined time according to the zero-crossing signal detected by the zero-crossing detection circuit.

Preferably, the infrared drive circuit includes an energy storage capacitor, a first switch, an inductor and a first diode, the energy storage capacitor is connected in series between the infrared heating film and the commercial power, and the energy storage capacitor is connected to the infrared One end connected to the heating film is connected to the source of the first switch through the inductor, and one end of the energy storage capacitor connected to the mains is connected to the source of the first switch through a first diode, The drain of the first switch is connected to the commercial power, and the gate of the first switch is connected to the infrared power adjustment module of the MCU.

Preferably, the infrared drive circuit further includes a second switch and a second diode, the common connection terminal of the inductor and the energy storage capacitor is connected to the drain of the second switch, and the commercial power is connected to the first The sources of the two switches are connected, and the second diode is connected between the drain of the second switch and the energy storage capacitor.

Preferably, the infrared driving circuit includes a triac connected between the infrared heating film and the commercial power supply, and an isolation optocoupler connected between the triac and the MCU infrared power adjustment.

(3) Beneficial effects

Since the electromagnetic heating device of the present invention includes an electromagnetic heating unit and an infrared heating unit, it can realize the heating of heating devices of different materials, and its application is not limited in a wide range; in addition, because the infrared heating unit is included, its maximum heating power is not affected by the coil disk. Limitation of maximum heating power.

In a preferred solution of the present invention, the MCU of the electromagnetic heating device further includes a cooking utensil material detection module for detecting the material of the cooking utensils placed on the induction cooker for heating, so as to select different heating units for heating according to the materials of different cooking utensils .

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a schematic diagram of a circuit module of an electromagnetic heating device of the present invention;

FIG. 2 is a schematic structural diagram of the EMC circuit 10 and the infrared heating unit 11 in FIG. 1;

3 is a schematic structural diagram of the EMC circuit 10 and the infrared heating unit 11 in FIG. 1;

4 is a schematic diagram of the connection relationship between the resonance circuit, the resonance synchronization detection circuit, the IGBT drive circuit and the MCU in the electromagnetic heating unit;

FIG. 5 is a partial enlarged schematic view of the position II in FIG. 4 .

Detailed ways

The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are intended to illustrate the present invention, but not to limit the scope of the present invention.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "left", "right", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, It is not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

The electromagnetic heating device of this embodiment includes an electromagnetic heating unit, an infrared heating unit and an MCU. Wherein, the MCU is connected to the electromagnetic heating unit and the infrared heating unit, and is used to control the electromagnetic heating unit and the infrared heating unit to heat separately or simultaneously.

Since the electromagnetic heating device provided in this embodiment is provided with an infrared heating unit, the non-ferrous magnetic cooking appliance can be heated. In addition, the infrared heating unit can also be combined with the electromagnetic heating unit to heat the ferromagnetic cooking utensils, so as to improve the heating speed and the highest heating power of the ferromagnetic cooking utensils.

The method for setting the infrared heating unit in this embodiment is: spraying the infrared heating film on the lower surface of the panel, or spraying the infrared heating film on the outer surface of the cooking utensil.

Further, the MCU of the electromagnetic heating device in this embodiment includes a pot detection module and a power distribution module. Wherein, when the pot detection module does not detect the existence of the cooking utensil, the heating power distributed by the power distribution module to the infrared heating unit and the electromagnetic heating unit is zero, so that the infrared heating unit and the electromagnetic heating unit are both No Heating When the pot detection module detects the presence of a cooking appliance, the power distribution module distributes heating power to at least one of the infrared heating unit and the electromagnetic heating unit. That is, the power distribution module distributes heating power only to the infrared heating unit, only distributes the heating power to the electromagnetic heating unit, or distributes the heating power to both the infrared heating unit and the electromagnetic heating unit.

In addition, the MCU of the electromagnetic heating device in this embodiment may further include a material detection module and a power distribution module. When the material detection module detects a ferromagnetic cooking utensil, the power distribution module switches to start the electromagnetic heating unit and/or the infrared heating unit to heat the cooking utensil; when the material detection module detects a non-ferromagnetic cooking utensil, the power distribution module switches to activate the infrared heating unit to heat the cooking utensil .

Specifically, the MCU further includes a heating switching reminder module, and the heating switching reminder module reminds the user to select a corresponding heating unit for heating according to the material of the cooking utensil detected by the material detection module.

This embodiment also provides a method for distributing heating power between the electromagnetic heating unit and the infrared heating unit: generally speaking, when the electromagnetic heating unit is continuously powered at a power lower than a certain power value (assuming the first predetermined power value) During heating, the IGBT of the induction cooker will have a serious hard-on situation, resulting in a large loss of the IGBT, a high temperature rise, and a shortened IGBT life. The heating of the infrared heating unit is resistive heating, which is different from the heating method of the electromagnetic heating unit, so it can be continuously heated when the power is lower than the first predetermined power value. In this embodiment, the first predetermined power value is equivalent to a critical value of whether the electromagnetic heating unit can realize continuous heating with the power value input by the user alone. The range of the first predetermined power value set in this embodiment is 800 watts to 1100 watts. Of course, the range of the first predetermined power value can also be adjusted according to the actual situation.

When the power value input by the user is greater than the first predetermined power value, this embodiment further optimizes the switching between the heating of the infrared heating unit and the electromagnetic heating unit. Specifically, this embodiment sets a second predetermined power value that is greater than the first predetermined power value. When the power detection module detects that the power input by the user is higher than the first predetermined power value and lower than the second predetermined power value, the power distribution The module switches to only start the heating of the electromagnetic heating unit, and correspondingly, the heating power allocated by the MCU to the infrared heating unit is zero. When the power detection module detects that the power input by the user is higher than the second predetermined power value, the power distribution module switches to start the heating of the electromagnetic heating unit and the infrared heating unit at the same time, and the corresponding MCU simultaneously heats the infrared The unit and the electromagnetic heating unit are assigned a certain value of heating power.

In the case that the power input by the user is higher than the second predetermined power value, the power distribution module of the MCU can distribute the corresponding heating power value to the electromagnetic heating unit and the infrared heating unit according to a preset algorithm. A preset algorithm provided in this embodiment is: the heating power value allocated by the power distribution module of the MCU to the electromagnetic heating unit is less than or equal to the second predetermined power value, and the heating power allocated by the power distribution module of the MCU to the infrared heating unit is input by the user The difference between the power value and the power value assigned to the electromagnetic heating unit. Of course, the power distribution module of the MCU can also distribute power to the infrared heating unit and the electromagnetic heating unit according to other preset algorithms.

The heating of the electromagnetic heating unit directly heats the cooking utensil. The cooking utensil itself is a heating element, while the infrared heating unit transfers the heat of the infrared heating film to the cooking utensil, that is, the infrared heating film is a heating element. Therefore, the heating of the electromagnetic heating unit The efficiency is higher than that of the infrared heating unit. When the power input by the user is greater than the first predetermined power value, the electromagnetic heating unit is preferably used for heating. However, when the power input by the user is greater than a certain value, that is, higher than the predetermined power value of the second power, if only the electromagnetic heating single heating is still activated, the electromagnetic heating unit will not only generate relatively large noise, but also the electromagnetic heating unit Electronic components such as IGBTs are also more susceptible to damage. Therefore, from the perspective of improving the heating efficiency, reducing the noise of the induction cooker and improving the life of the electronic components of the induction cooker, when the power input by the user is higher than the predetermined power value of the second power, the power distribution module switches to start the heating of the infrared heating unit and the electromagnetic heating unit at the same time. Also based on the above considerations, in this embodiment, the range of the second predetermined power value is set to be 1500 watts to 1700 watts, and of course, corresponding adjustments can be made according to specific conditions.

The following table is a specific algorithm for the MCU to allocate heating power to the infrared heating unit and the electromagnetic heating unit according to the heating power input by the user in this embodiment. In the table below, the rated heating power of the induction cooker is 2100W. It can be seen from the table that the induction cooker provided in this embodiment can provide continuous heating between 100W and 2100W, so that it can meet various applications such as continuous low-power soup cooking.

Table 1

In addition, in consideration of increasing the maximum heating power of the induction cooker, the range of the second predetermined power value may also be set to 2000 watts to 2200 watts. This power range is roughly equivalent to the maximum rated power range that the existing household induction cooker can provide. When the heating power value input by the user exceeds the second predetermined power value, the power distribution module switches to start the heating of the infrared heating unit and the electromagnetic heating unit at the same time. If the maximum rated heating power that the infrared heating unit can provide is 1000 watts, the maximum heating power of the induction cooker can be increased to 3000 watts to 3200 watts by using this combined heating method of the infrared heating unit and the electromagnetic heating unit.

It is worth noting that when the electromagnetic heating unit and the infrared heating unit are switched between heating, there will be a problem of discontinuous heating. Preferably, in this embodiment, when the electromagnetic heating unit and the infrared heating unit are switched, the latter heating mode has been When starting, let the previous heating mode continue for another delay time. For example, when switching from heating only by the infrared heating unit to heating by the electromagnetic heating unit only, there is a short period of time (about 5 seconds) in the middle where the infrared heating unit and the electromagnetic heating unit are in a common heating state.

The electromagnetic heating device in this embodiment may include both the above-mentioned pot inspection module and material detection module, or at least one of the pot inspection module or the material detection module. The following embodiment provides a method for pan inspection and material inspection based on a heating unit.

The following describes the circuit of the electromagnetic heating unit in conjunction with FIG. 1, FIG. 4 and FIG. 5. The electromagnetic heating unit generally includes at least a resonant circuit and an electromagnetic drive circuit. One end of the electromagnetic drive circuit is connected to the resonant circuit, and the other end is connected to the electromagnetic power adjustment module in the MCU. connected, the electromagnetic power adjustment module inputs a PWM signal with a first predetermined duty cycle to the electromagnetic drive circuit according to the assigned heating power value. The resonant circuit includes a switching element, a resonant capacitor and a resonant inductance. The resonant capacitor and the resonant inductance are connected in parallel. One of the common connection ends of the resonant capacitor and the resonant inductance is connected to the rectified mains, and the other common connection end is connected to the collector of the switching element. , in which the switching element generally adopts IGBT.

The electromagnetic heating unit also includes a resonance synchronization detection circuit. One end of the resonance synchronization detection circuit is respectively connected with the two common connection ends of the resonance capacitor and the resonance inductance, that is, there is a branch at the end connected to the collector of the IGBT to detect the collector of the IGBT. The other end of the resonance synchronization detection circuit is connected to the MCU. When the resonance synchronization detection circuit detects that the voltage of the collector of the IGBT tube is the lowest voltage (generally zero), the electromagnetic ratio adjustment module of the MCU drives the electromagnetic The circuit outputs a PWM signal with a first predetermined duty cycle.

The electromagnetic heating unit can also include a zero-crossing detection circuit. One end of the zero-crossing detection circuit is connected to the rectified mains to detect the zero-crossing signal of the mains, and the other end is connected to the MCU. After receiving the zero-crossing signal, the electromagnetic power adjustment module The reinitialized first predetermined duty cycle PWM signal is input to the electromagnetic drive circuit.

The electromagnetic heating unit may further include a surge detection circuit, an over-temperature detection circuit, an over-voltage detection circuit and an over-current detection circuit. The surge detection circuit detects the voltage signal of the mains. When the mains suddenly has a high positive voltage or a negative voltage, the surge detection circuit sends a signal to the MCU to turn off the IGBT. The over-temperature detection circuit sends a signal to the MCU to turn off the IGBT when the temperature of the IGBT as a switching element reaches a certain value. The overvoltage detection circuit sends a signal to the MCU to turn off the IGBT when the collector voltage of the IGBT as the switching element reaches a certain value. The overcurrent detection circuit sends a signal to the MCU to turn off the IGBT when the collector current of the IGBT as the switching element reaches a certain value.

Obviously, the electromagnetic heating unit may have other circuits, which are not limited by the above example circuits. In addition, the electromagnetic heating unit can also use other circuits different from those listed in this embodiment to realize electromagnetic heating.

For the above circuit in the electromagnetic heating unit listed in this embodiment, the pot detection module in the MCU can cooperate with the resonance circuit, electromagnetic drive circuit and synchronous resonance circuit to detect the existence of cooking utensils. The material detection module in the MCU can also cooperate with the resonance circuit, the electromagnetic drive circuit and the synchronous resonance circuit in the MCU to complete the detection of the material of the cooking utensil.

Specifically, first, a pot detection pulse is input to the electromagnetic drive circuit through the electromagnetic power adjustment module in the MCU. The ON time of the pot detection pulse is 6us-10us, and the interval time between the transmission of the pot detection pulse is about 1S～2S. The pot detection pulse makes the resonant circuit conduct. If the induction cooker is loaded with cooking utensils, the energy of the resonant circuit is consumed faster, and the output voltage of the resonant synchronous detection circuit is turned less frequently. If there is no cooking utensil on the induction cooker, the energy consumption of the resonance circuit is relatively slow, and the output voltage of the resonance synchronization detection circuit is turned over more times. The pot detection module determines whether there is a cooking utensil by judging whether the number of times the output voltage of the resonance synchronous detection circuit is turned over reaches a predetermined number of times. For example, if the predetermined number of times is 10, when the number of times the output voltage of the resonance synchronous detection circuit is turned over is greater than or equal to 10, it is determined that the cooking utensil exists;

The material detection module judges the material of the cooking utensil by detecting the interval time between the outputs of the adjacent inversion voltages of the resonance synchronous detection circuit. For example, after the electromagnetic power adjustment module in the MCU inputs a pot detection pulse to the electromagnetic drive circuit, within a predetermined time, the voltage output by the resonance synchronization detection circuit has a total of 12 inversions. When the inversion cycle time is about 35us , it is determined that the material of the cooking utensil is 430 steel, and when the turning cycle time is about 25us, the material of the cooking utensil is determined to be 304 steel.

Figure 4 shows the specific composition of the resonance circuit and the resonance synchronous detection circuit. The following describes the working principle of detecting the existence of a cooking utensil and the working principle of detecting the material of the cooking utensil in combination with the resonance circuit, the electromagnetic driving circuit and the resonance synchronous detection circuit of the electromagnetic heating unit. The direction of the arrow at the far left in Figure 4 refers to the rectified mains input.

Before the induction cooker starts to heat, a pulse with a certain conduction time is output. When the electromagnetic drive circuit, that is, the IGBT drive circuit in Figure 5, is turned on, the coil disk LH in the resonant circuit, that is, the resonant inductor, has a current flowing from the left to the right. The voltage signal Va at the left end of the resonant capacitor C5 in the resonant circuit is divided by R49, R51, R52, R53, R1, and R5 in the resonant synchronous detection circuit, and is input to the non-inverting input of the internal comparator of the MCU, and the voltage at the right end of the resonant capacitor C5 The voltage signal Vb divided by R7, R2, R6, R57 in the resonance synchronization detection circuit is input to the inverting input terminal of the internal comparator of the MCU. At this time, the voltage at the left end of the resonant capacitor C5 is clamped to the mains voltage, and the voltage at the right end of the resonant capacitor C5 is directly pulled to the ground level by the IGBT (that is, the part connected to the left end of the IGBT drive circuit in Figure 4), at this time Va>Vb.

When the IGBT drive circuit turns off the IGBT, the coil disk LH in the resonant circuit cannot change abruptly due to the inductance effect, and continues to flow from left to right, and charges the resonant capacitor C5, so that the voltage at the right end of the resonant capacitor C5 continues to rise until The LH current is released. When the current of LH is 0, the voltage at the right end of C5 reaches the highest, and Va<Vb at this time.

When Va<Vb, the resonant capacitor C5 in the resonant circuit turns to discharge to the coil disk LH in the resonant circuit. Current flows from the right end to the left end of the coil disk LH. Until the electric energy of C5 is released, the voltage on the left side of C5 is equal to the voltage on the right side. Since the coil disk LH still has current flowing from right to left, the inductive effect causes the current in the coil disk LH to continue to flow from right to left. At this time, the voltage at the left end of the resonant capacitor C5 is clamped to the mains voltage, and the voltage at the right end of C5 is continuously pulled down. Until Vb<Va, the internal comparator of the MCU generates a pulse output of a rising edge, the counter starts to count up, and the timer is enabled for periodic timing. The pot detection module in the MCU includes at least the internal comparator and counter. Correspondingly, the material detection module in the MCU includes at least the internal comparator and the timer.

Because the energy of the resonant circuit has not been released, the resonant circuit will repeat the above process. When Vb<Va occurs again, stop the timer for periodic timing, read the cycle time value at this time, and determine the type of cooking utensils. After a certain period of time (the resonant circuit is oscillated by the pot detection pulse), such as 200ms to 500ms, read the value of the counter.

The above method combining the electromagnetic drive circuit, the resonance circuit and the resonance synchronous detection circuit is quite effective in detecting the existence of the ferromagnetic cooking utensil and detecting the material of the ferromagnetic cooking utensil. Of course, the detection of the existence of the cooking utensil and the detection of the material of the cooking utensil can also be realized in other ways. For example, an ultrasonic emission circuit and an ultrasonic detection circuit are set in the electromagnetic heating unit. The pot detection module judges whether the cooking utensil exists by whether the ultrasonic detection circuit can detect the ultrasonic reflection signal, and the material detection module detects the frequency and frequency of the ultrasonic reflection signal. Amplitude range to judge the material of cooking utensils.

With reference to Figure 2 and Figure 3, the following describes the infrared heating unit. The infrared heating unit includes an infrared heating circuit and an infrared heating drive circuit. The infrared heating circuit includes an infrared heating film connected between the neutral and live wires of the mains. One end of the infrared drive circuit It is connected between the infrared heating film and the mains (that is, one end of the infrared drive circuit can be connected between the infrared heating film and the mains zero line, or between the infrared heating film and the mains live line. time), the other end of the infrared drive circuit is connected to the infrared power adjustment module in the MCU, and the infrared power adjustment module inputs the PWM signal of the second predetermined duty cycle to the infrared drive circuit according to the assigned heating power value.

Further, the infrared power adjustment module may also input the PWM signal of the second predetermined duty cycle to the infrared driving circuit at a predetermined time according to the zero-crossing signal detected by the zero-crossing detection circuit in the electromagnetic heating unit.

There are two types of infrared heating driving circuits provided in this embodiment. As shown in FIG. 2 , the first infrared driving circuit provided in this embodiment includes an isolation subunit and a switch subunit. The switch subunit is connected in series with the infrared heating film and the commercial power supply. In between, the isolation subunit is connected between the switch subunit and the infrared power adjustment module. That is, the isolation subunit can receive the PWM signal of the second predetermined duty ratio sent by the infrared power adjustment module to control the on and off of the switch subunit, thereby controlling whether the infrared heating circuit is on or off.

Specifically, the isolation subunit is an isolation optocoupler U10, the switch subunit is a triac TR1, and the isolation optocoupler U10 includes a light emitting device and a photosensitive device. The positive electrode S1 of the light-emitting device is connected to the DC power supply (providing a voltage of 5V or 3.5V), and the negative electrode S2 is connected to the infrared power adjustment module of the MCU. In this connection, the photosensitive device is turned on when the infrared power adjustment module emits a low level. Of course, the positive electrode S1 of the light-emitting device can also be connected to the infrared power adjustment module of the MCU, and the negative electrode S2 of the light-emitting device is grounded. In this connection, the photosensitive device is turned on when the infrared power adjustment module emits a high level. The photosensitive device is a triac, the first anode S6 is connected to the second main electrode T2 of the triac TR1, and the second anode S4 is connected to the gate of the triac TR1. The second main electrode T2 of the triac TR1 is connected to the far-infrared heating film, and the first main electrode T1 of the triac TR1 is connected to the mains.

A first resistor R81 and a second resistor R82 are connected in series between the first anode S6 of the photosensitive device and the second main electrode T2 of the triac TR1 in sequence. A first capacitor C201 is connected in series between the common terminal of the first resistor R81 and the second resistor R82 and the first main electrode T1 of the triac TR1; a third resistor R80 is connected between the positive electrode S1 of the light emitting device and the DC power supply. The first resistor R81, the second resistor R82, the third resistor R80 and the first capacitor C201 can turn on the triac TR1 with a suitable current and voltage, and play the role of filtering and stabilizing the triac TR1 control circuit. effect.

This infrared drive circuit is based on a triac adjustment control circuit, and the isolation subunit and the switch subunit can also be replaced with corresponding components in the relay, that is, changed to a control circuit based on relay adjustment. Of course, the isolation subunit and the switch subunit can also be replaced by other electronic components, which are not limited to this embodiment.

Corresponding to this infrared drive circuit based on triac, it combines two types of zero-crossing detection circuit and infrared power adjustment module to adjust infrared heating power. The first infrared power adjustment mode is more stable, and the second infrared power adjustment mode responds faster.

Specifically, in the first method for adjusting the infrared heating power provided in this embodiment: the frequency of the current is 50HZ, the duration of one half-wave is 10ms, the duration of a square wave cycle in the PWM signal is 100ms, and the infrared heating The membrane heats up when the PWM signal is high and stops heating when the PWM signal is low.

First, the infrared power adjustment module calculates the high level time t1 and the low level time t2 within one square wave cycle of the PWM signal according to the allocated heating power. Table 2 shows the relationship between the allocated infrared heating power and the high-level time t1 and the low-level time t2. In Table 2, the maximum heating power provided by the infrared heating film during the entire square wave cycle is 1000w. When the heating power value assigned by the infrared power adjustment module is 800w, the high level time t1 of the square wave cycle of the PWM signal is adjusted from 100ms to 80ms, and the corresponding low level time t2 is adjusted from 0ms to 20ms. That is, in a square wave cycle of a PWM signal, the infrared heating circuit is turned on in 8 half-wave cycles of the commercial power. When the heating power value allocated by the infrared power adjustment module is 500w, the high level time t1 is adjusted from 80ms to 50ms, and the corresponding low level t2 is adjusted from 20ms to 50ms. Generally speaking, the larger the heating power value assigned to the infrared power adjustment module, the longer the high level time t1 and the shorter the low level time t2 in one square wave cycle of the PWM signal.

During the heating process of the infrared heating film, if a new heating power is allocated, the infrared power adjustment module will recalculate the high-level time and low-level time of the square wave period of the PWM signal according to the algorithm in Table 2, and then pass The zero-crossing detection circuit detects the zero-crossing signal. When the zero-crossing signal is detected, the infrared power adjustment module will send the recalculated PWM signal to the infrared driving circuit.

The second method of adjusting the infrared heating power provided in this embodiment is different from the first one in that the duration of a square wave cycle in the PWM signal is set to 10ms, which is the same as the half-wave cycle of the commercial power. Take the infrared heating film as an example, the maximum heating power that can be provided by heating in the whole square wave cycle is 1000w. When the heating power value assigned by the infrared power adjustment module is 800w, the high level time t1 of a square wave cycle of the PWM signal is changed from 10ms to 8ms, and the corresponding low level time t2 is changed from 0ms to 2ms. When the heating power value allocated by the infrared power adjustment module is 500w, the high level time t1 is adjusted from 8ms to 5ms, and the corresponding low level t2 is adjusted from 2ms to 5ms.

Similarly, in the heating process of the infrared heating film, if a new heating power is allocated, the infrared power adjustment module will also recalculate the high-level time and low-level time in the square wave period of the PWM signal, and then pass the zero-crossing detection. The circuit detects the zero-crossing signal. When the zero-crossing signal is detected, the infrared power adjustment module will send the recalculated PWM signal to the infrared drive circuit.

Set power (W) Control period (ms) Turn-on period (ms) Off period (ms) 900 100 90 10 800 100 80 20 700 100 70 30 600 100 60 40 500 100 50 50 400 100 40 60 300 100 30 70 200 100 20 80 100 100 10 90

Table 2

The above are just two ways of adjusting the infrared heating power by the triac circuit combined with the infrared power adjustment module and the zero-crossing detection circuit, and the power adjustment algorithm can also adopt other ways. The hardware of the adjustment circuit may not be combined with the zero-crossing detection circuit. The method of the infrared power adjustment module to adjust the infrared heating power does not necessarily adopt the method of PWM signal.

The second infrared heating driving circuit provided in this embodiment is a PFC circuit, please refer to FIG. 3 . The PFC circuit includes an energy storage capacitor, a first switch, an inductance and a first diode. The energy storage capacitor is connected in series between the infrared heating film and the mains, and one end of the energy storage capacitor connected to the mains is connected to the source of the first switch through an inductance. The end of the energy storage capacitor connected to the infrared heating film is connected to the source of the first switch through the first diode, the drain of the first switch is connected to the mains, and the base of the first switch is connected to the MCU Infrared power conditioning module connection.

Further, the infrared drive circuit also includes a second switch and a second diode, the common connection terminal of the inductor and the energy storage capacitor is connected to the drain of the second switch, the mains is connected to the source of the second switch, and the second diode is connected to the drain of the second switch. The tube is connected between the drain of the second switch and the energy storage capacitor, and the base of the second switch is connected with the infrared power adjustment module of the MCU.

Among them, the first switch and the second switch correspond to Q1 and Q2 shown in Figure 3 respectively, and they are CMOS transistors with high power and high withstand voltage; the inductance corresponds to L1 in Figure 3, and its inductance value is above 400uH; The distribution of the first diode and the second diode corresponds to D1 and D2 in Figure 3, and they are rectifier diodes with high power and high reverse withstand voltage; the energy storage capacitors correspond to C1, C2, and C3 in Figure 3, They are all capacitors with large capacitance and high withstand voltage. The base of the first switch corresponds to Vc L in FIG. 3 , and the base of the second switch corresponds to Vc H in FIG. 3 .

The infrared power adjustment module in the MCU combines the PFC circuit to adjust the infrared power, which is a voltage-based power adjustment method. The specific principles are as follows:

When the infrared power adjustment module sends a PWM signal of full duty cycle to the base Vc L of the first switch, and sends a PWM signal of zero duty cycle to the base Vc H of the second switch, that is, the first switch Q1 is fully open , The second switch Q2 is fully closed, the half-wave rectified mains power is rectified, filtered and stabilized by the inductor L1 and the energy storage capacitors (C1, C2, C3), and then provides a stable DC voltage of about 310V to the infrared heating film.

When the output power needs to be reduced, the infrared power adjustment module sends a PWM signal with a certain duty cycle to the base Vc L of the first switch, and sends a zero duty cycle PWM signal to the base Vc H of the second switch. The switch Q1 is opened intermittently, and the second switch Q2 is fully closed. When the first switch Q1 is turned on, the rectified mains power charges the energy storage capacitors (C1, C2, C3) through the inductor L1 and the second diode D2, and flows through the infrared heating film at the same time, so that the infrared heating film continues to generate heat. When the first switch Q1 is turned off, due to the inductance effect, the inductor L1 keeps the current current flow unchanged, and continues to charge the energy storage capacitors (C1, C2, C3), and flows through the infrared heating film, so that the infrared heating film generates output power.

The larger the duty cycle of the PWM signal sent by the infrared power adjustment module to the base Vc L of the first switch Q1, the greater the energy stored by the inductor L1 and the energy storage capacitors (C1, C2, C3), and the higher the operating voltage of the infrared heating film. High, the corresponding infrared heating film output power is greater. The second switch Q2 is fully closed, and the first switch Q1 is used to adjust the power of the infrared heating film, and the working voltage of the infrared heating film can be adjusted in the range of 0 to 310V.

When the power needs to be increased, the infrared power adjustment module sends a PWM signal with a full duty cycle to the base Vc L of the first switch, and sends a PWM signal with a certain duty cycle to the base Vc H of the second switch, that is, the first switch. The switch Q1 is fully open, and the second switch Q2 is open intermittently. When the second switch Q2 is turned on, the rectified commercial power is short-circuited to ground by the second switch Q2 after passing through the inductor L1, and a large current flows through the inductor L1; due to the damping effect of the second diode D2, the energy storage capacitor ( The currents of C1, C2, C3) cannot flow to the ground through the second switch Q2, and continue to discharge through the infrared heating film, so that the infrared heating film continues to output power. When the second switch Q2 is turned off, the inductor keeps the current current flow unchanged due to the inductance effect L1, and the current of the inductor L1 charges the energy storage capacitors (C1, C2, C3) through the second diode D2, and flows through the infrared heating film at the same time. , so that the infrared heating film continues to generate heat.

The larger the duty cycle of the PWM signal sent by the infrared power adjustment module to the base VcH of the second switch, the greater the energy stored by the inductor L1 and the energy storage capacitors (C1, C2, C3), and the greater the operating voltage of the infrared heating film ( The maximum working voltage can reach 550V) the corresponding infrared heating film output power is larger. The first switch Q1 is fully turned on, and the second switch Q2 is used to adjust the power of the infrared heating film, and the working voltage of the infrared heating film can be adjusted in the range of 310 to 550V.

Obviously, the specific forms of the infrared heating drive circuit and the infrared heating circuit are not limited by this embodiment, and any feasible form obtained by using the prior art should be included in the protection scope of the present application.

The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that various combinations, modifications or equivalent replacements to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and should cover within the scope of the claims of the present invention.

Claims (11)

1. an electromagnetic heating device, is characterized in that, comprises: An electromagnetic heating unit, an infrared heating unit and an MCU, the infrared heating unit continuously heats when the power input by the user is lower than a first predetermined power value, and the electromagnetic heating unit and the infrared heating unit are heated when the power input by the user is higher than a second predetermined power value The second predetermined power value is higher than the first predetermined power value, and the MCU is connected to the electromagnetic heating unit and the infrared heating unit to control the electromagnetic heating unit and the infrared heating unit. Heating individually or simultaneously; The electromagnetic heating unit includes an electromagnetic drive circuit and a zero-crossing detection circuit, and the MCU includes an electromagnetic power adjustment module; the electromagnetic power adjustment module is connected to the electromagnetic drive circuit, and detects the zero-crossing according to the assigned heating power value and the zero-crossing detection circuit. The zero-crossing signal detected by the circuit inputs the PWM signal of the first predetermined duty cycle to the electromagnetic drive circuit; The infrared heating unit includes an infrared drive circuit, the MCU includes an infrared power adjustment module, and the infrared power adjustment module is connected to the infrared drive circuit, and is based on the assigned heating power value and the crossover detected by the zero-crossing detection circuit. The zero signal inputs the PWM signal of the second predetermined duty cycle to the infrared driving circuit. 2. The electromagnetic heating device according to claim 1, wherein the MCU comprises a pot detection module and a power distribution module; When the pot detection module does not detect the existence of cooking utensils, the heating power distributed by the power distribution module to the infrared heating unit and the electromagnetic heating unit is zero; when the pot detection module detects the existence of cooking utensils when the power distribution module distributes heating power to at least one of the infrared heating unit and the electromagnetic heating unit. 3. The electromagnetic heating device according to claim 2, characterized in that, The electromagnetic heating unit also includes: A resonant circuit, the resonant circuit includes a switching element, a resonant capacitor and a resonant inductance, the resonant capacitor and the resonant inductance are connected in parallel, and one of the common connection ends of the resonant capacitor and the resonant inductance is connected to the rectified commercial power, and the other common The connection terminal is connected with the collector of the switching element; the base of the switching element is connected with the electromagnetic drive circuit; a resonance synchronization detection circuit, one end is connected to the collector of the switching element to detect the voltage of the collector of the switching element, and the other end is connected to the MCU; After the MCU sends a pot detection pulse to the electromagnetic drive circuit, the pot detection module determines whether the cooking utensil exists according to whether the number of times of voltage inversion output by the resonance synchronization detection circuit is lower than a predetermined number of times. 4 . The electromagnetic heating device according to claim 1 , wherein the MCU comprises a material detection module and a power distribution module, and when the material detection module detects a ferromagnetic cooking utensil, the power distribution module Switch to activate the electromagnetic heating unit and/or the infrared heating unit to heat the cooking appliance; when the material detection module detects a non-ferromagnetic cooking appliance, the power distribution module switches to activate the infrared heating The heating unit heats the cooking appliance. 5 . The electromagnetic heating device according to claim 4 , wherein the MCU comprises a heating switching reminder module, and the heating switching reminder module reminds the user to select the corresponding heating according to the cooking utensil material detected by the material detection module. 6 . Unit heating. 6. The electromagnetic heating device according to claim 4, wherein: The electromagnetic heating unit also includes: A resonant circuit, the resonant circuit includes a switching element, a resonant capacitor and a resonant inductance, the resonant capacitor and the resonant inductance are connected in parallel, and one of the common connection ends of the resonant capacitor and the resonant inductance is connected to the rectified commercial power, and the other common The connection terminal is connected with the collector of the switching element, and the base of the switching element is connected with the electromagnetic drive circuit; a resonance synchronization detection circuit, one end is connected to the collector of the switching element to detect the voltage of the collector of the switching element, and the other end is connected to the MCU; After the MCU sends the pot detection pulse to the electromagnetic drive circuit, the material detection module determines the material of the cooking utensil by detecting the interval time between adjacent inversion voltages output by the resonance synchronization detection circuit. 7. The electromagnetic heating device according to any one of claims 1 to 6, wherein the infrared heating unit further comprises an infrared heating circuit; the infrared heating circuit has a An infrared heating film, one end of the infrared driving circuit is connected between the infrared heating film and the commercial power, and the other end of the infrared driving circuit is connected to the infrared power adjustment module. 8 . The electromagnetic heating device according to claim 7 , wherein one end of the zero-crossing detection circuit is connected to the rectified commercial power to detect the zero-crossing signal of the commercial power, and the other end is connected to the MCU. 9 . 9 . The electromagnetic heating device according to claim 7 , wherein the infrared drive circuit comprises an energy storage capacitor, a first switch, an inductor and a first diode, and the energy storage capacitor is connected in series with the infrared heating device. 10 . Between the film and the mains, the end of the energy storage capacitor connected to the infrared heating film is connected to the source of the first switch through the inductance, and the end of the energy storage capacitor connected to the mains is connected to the source of the first switch through the inductance. The diode is connected to the source of the first switch, the drain of the first switch is connected to the commercial power, and the gate of the first switch is connected to the infrared power adjustment module of the MCU. 10 . The electromagnetic heating device according to claim 9 , wherein the infrared driving circuit further comprises a second switch and a second diode, and the common connection terminal of the inductor and the energy storage capacitor is connected to the The drain of the second switch is connected, the commercial power is connected to the source of the second switch, and the second diode is connected between the drain of the second switch and the energy storage capacitor. 11. The electromagnetic heating device according to claim 7, wherein the infrared drive circuit comprises a triac connected between the infrared heating film and the commercial power supply, and is connected between the triac and the MCU Isolated optocoupler between infrared power conditioning modules.

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