CN101309529B - An intelligent control device and method for a high-power energy-saving electromagnetic cooker - Google Patents

Abstract

The invention relates to an intelligent control device and method for a high-power energy-saving electromagnetic cooker, which includes a controllable rectification filter module, an inverter module and a microcomputer control module, and is characterized in that: the controllable rectification filter module rectifies a three-phase AC power supply The DC power supply; the inverter module inverts the DC power supply into a high-frequency AC power supply, and then converts the electric energy into electromagnetic energy through the resonant inductor to radiate to the bottom of the pot to generate eddy current, which heats the pot due to the thermal effect of the eddy current; the microcomputer control module is the whole The core of the system is used to collect data and send control information to each module; the device adopts a series of advanced controls such as rectifier bridge trigger control of PI regulator, intelligent self-adaptive constant power control, intelligent soft start control, intelligent pot detection control, etc. Strategies to enhance the stability and safety of induction cooker work. While saving electric energy, the electromagnetic cooker can minimize the harmonic pollution of the equipment to the power grid, and is suitable for use in various kitchens and restaurants.

Description

An intelligent control device and method for a high-power energy-saving electromagnetic cooker

technical field

The invention belongs to a control device and a control method for an electromagnetic cooker, in particular to an intelligent control device and a method for a high-power energy-saving electromagnetic cooker.

Background technique

With the general improvement of people's living standards, the concepts of environmental protection and energy conservation have begun to take root in the hearts of the people. As a clean, energy-saving and easy-to-use kitchen equipment, the induction cooker has begun to replace the traditional stove and enter thousands of households. At present, most of the electromagnetic cookers sold on the market are low-power household electromagnetic cookers, and their power is mostly below 2000W. Because of their small power, it is difficult to meet the high-power requirements of school cafeterias, factories, hotels, hotels, institutions, and large commercial centers. need.

At present, the existing high-power electromagnetic cookers all adopt the mode of frequency modulation to adjust the power output. When the output power is small, its operating frequency is far away from the resonance point frequency of the resonant circuit, the reactive power generated in the main circuit is large, the power factor of the electromagnetic cooker is low, the energy conversion efficiency is low, and a lot of electric energy is wasted. Larger reactive power will also cause harmonic pollution to the power grid, and larger reactive current increases the heating of high-power electronic devices such as IGBTs, reducing the working stability, safety and use of IGBTs and other electronic devices. life. The current high-power electromagnetic cooker also adopts the control method of fixed gear and fixed frequency. When the gear is fixed, the working frequency of the electromagnetic cooker is fixed. The fixed-range and fixed-frequency control method cannot accurately control the power output of each gear. When the grid voltage fluctuates, the size of the pot changes, the material of the pot changes, and the distance between the pot and the heating coil changes, the output power will vary under different conditions. There is a big difference, the output power of the induction cooker cannot be accurately controlled, the heating firepower of each gear is unstable, and the control accuracy is poor. In addition, during the heating process of the induction cooker, when the pot is taken away, the system often cannot judge whether there is a pot in time, so as to continue to work. In the case of no pot, it will cause a large amount of electromagnetic leakage and waste of electric energy, reducing the Energy conversion efficiency.

Contents of the invention

The purpose of the present invention is to provide an intelligent control device and method for a high-power energy-saving electromagnetic cooker with high efficiency, energy saving, clean environment, strong safety and high reliability, which adopts microcomputer control design, so as to overcome the above-mentioned deficiencies.

In order to achieve the above purpose. The invention is composed of a controllable rectification and filtering module, an inverter module and a microcomputer control module, and its characteristics are:

Controllable rectification and filtering module: integrated with AC power input interface, as the energy input of the whole device, the three-phase rectification triggers the control circuit to perform full-bridge controllable rectification, and provides DC power for the inverter module through the output interface after filtering;

Inverter module: The DC power is converted into a high-frequency AC power through a series resonant circuit. After passing through the coil plate L4, the high-frequency AC energy generates an alternating electromagnetic field. After the pot is placed on the coil plate, the electromagnetic field radiates to the bottom of the pot to generate Eddy current, due to the thermal effect of eddy current, Joule heat is generated, thereby heating the pan;

Microcomputer control module: connected with other modules through data lines, real-time detection of DC bus voltage, DC bus current, high-frequency AC current, coil disk L4 temperature, core temperature and gear input signals, and issue control commands, controlled by the microcomputer The chip controls the PWM unit to output a single PWM signal, and obtains two PWM driving signals with dead zone control through the hardware dead zone control circuit to drive the inverter module.

The above-mentioned controllable rectification filter module is composed of common-mode inductor L1, fuses F1-F3, power supply interference suppression capacitors C1-C3, relay, three-phase controllable rectifier bridge, three-phase rectifier bridge trigger circuit, synchronous transformer, PI regulator 1, Differential mode inductors L2~L3, filter capacitor C4, DC voltage detector UT and DC current detector IT1; the voltage signal detected by DC voltage detector UT is divided into two circuits, one as the voltage feedback signal U _b of the rectification control circuit, and the other One signal U _d and the output of the DC current detector IT1 are connected to the signal conditioning circuit of the microcomputer control module, and together serve as feedback signals for intelligent self-adaptive constant power control.

The above inverter module is composed of high-power switching tubes IGBT1~IGBT2, IGBT isolation drive circuit, resonant capacitor C5~C6, AC current detector IT2 and coil disk L4; The PWM signal for dead zone control is provided, and the power switch tube is driven to work after passing through the IGBT drive module; an AC current detector IT2 is connected in series on the main resonant circuit, and the output of IT2 is connected to the signal conditioning circuit of the microcomputer control module, and then sent to the microcomputer control module. The controller (MCU) is used as a pot detection control and overcurrent protection signal.

The above-mentioned microcomputer control module includes a gear position input circuit, a fan relay drive circuit, a three-phase power relay drive circuit, a microcontroller (MCU), a power supply module, a signal conditioning circuit, a hardware dead zone control circuit, a safety protection circuit, and a digital tube display circuit , sound and light alarm circuit and communication interface circuit; the external power supply provides power for each circuit of the microcomputer control module after passing through the power module; the fan and three-phase power relay drive circuit is controlled by the I/O port of the MCU, and the output of the drive circuit is connected with the relay connected in groups; the signals of DC voltage detector UT, DC current detector IT1, AC current detector IT2, temperature detector TT1~TT2 and the gear input circuit are sent to the A/D sampling unit of the MCU after passing through the signal conditioning circuit; The bit input circuit adopts the method of resistor series voltage division, each gear corresponds to a voltage, and after the voltage follower and isolation amplifier circuit, it is sent to the A/D sampling unit of the MCU as a given signal corresponding to the power of different gears; the digital tube The display circuit displays the current working gear of the induction cooker, and displays a fault code in a fault state.

The above-mentioned hardware dead zone control circuit is made up of logic circuit and resistance, electric capacity, and the input of hardware dead zone control circuit is connected with the PWM unit output pin of microcontroller (MCU); The phase device is divided into two complementary signals. When the signal changes from low level to high level, the capacitor is charged through the resistor, so that the time is delayed when the PWM signal changes from low level to high level, and when the signal changes from high level to low level. , The capacitor is quickly discharged through the reverse diode, so that the PWM signal is not delayed when it changes from high level to low level, so as to obtain two complementary PWM signals with dead zones.

The above-mentioned microcomputer control module is integrated with a communication interface unit, which adopts the RS-485 bus communication protocol to realize remote communication; the microcomputer control module can be connected to the LCD controller through the RS-485 bus or connected to the PC after converting RS-485 to RS-232. Provide real-time working status and fault information of the induction cooker to realize remote online monitoring and fault diagnosis.

The present invention also provides an intelligent control method for a high-power energy-saving electromagnetic cooker. The control device is composed of a controllable rectification filter module, an inverter module and a microcomputer control module. The control method is: adopting an adaptive constant power control method, adjusting The output voltage of the rectifier bridge and the operating frequency of the fine-tuning inverter module achieve the purpose of adjusting the constant power output of each gear, wherein:

The controllable rectification and filtering module first filters the three-phase AC power supply, and then uses the three-phase rectification trigger control based on the PI regulator to perform full-bridge rectification. After filtering again, a stable and smooth DC voltage is obtained, which is used as the input voltage of the inverter module. ;

The inverter module adopts the pulse frequency modulation (PFM) method to invert the DC power into AC power through the series resonant circuit. Its operating frequency is slightly higher than the resonant frequency of the resonant circuit. The variable power supply converts electric energy into electromagnetic energy through the coil disk L4, and the electromagnetic field radiates to the bottom of the pot to generate eddy currents, which generate Joule heat due to the thermal effect of the eddy currents, thereby heating the pots;

The microcomputer control module detects the DC bus voltage, DC bus current, high-frequency AC current, coil disk temperature, core temperature and gear input signals in real time. After calculation and processing, the PWM unit is controlled by the micro-control chip to output a single-channel PWM signal. The hardware dead zone circuit obtains two PWM driving signals with dead zone control to drive the inverter module.

The above self-adaptive constant power control method includes two parts: when adjusting in a larger power range, adjust the output voltage of the rectifier bridge to adjust the power output; The method of frequency modulation and power adjustment fine-tunes the working frequency of the inverter module IGBT, so that the output power intelligently and adaptively follows the given power of the gear, and precisely controls the heating power of each gear.

The above-mentioned controllable rectification module adopts the trigger control of the three-phase rectifier bridge of the PI regulator, and the given signal U _I of the output voltage of the three-phase rectifier bridge is given from the gear input circuit, and the feedback of the given signal U _I and the detection of the DC voltage detector The voltage signal U _b is compared to obtain the voltage deviation ΔU, through the PI regulator 1, the phase-shift control voltage U _C of the rectification trigger circuit is adjusted, and the trigger angle of the three-phase rectifier bridge thyristor is changed, thereby adjusting the three-phase controllable rectifier bridge. Output voltage, change the output power of the induction cooker.

The above-mentioned induction cooker adopts a soft start method, and both the rectification trigger control circuit and the constant power control circuit adopt a control method based on PI regulation. When starting up and shifting gears, the voltage output by the rectifier bridge changes slowly and the power output by the induction cooker changes slowly. Suppress the sudden change of current in the main circuit, realize the soft start of high-power devices, and protect the safety of high-power devices.

The above-mentioned electromagnetic cooker adopts a low-power pot detection control method. In the state of pot detection, the electromagnetic cooker adopts an intermittent working mode to send a pulse signal for detecting a pot. The PWM blocks the signal, so that the upper and lower bridge arms of the IGBT module are in the off state at the same time.

Since the present invention adopts a controllable rectification method for power adjustment output, which is obviously different from other control methods of electromagnetic cooker frequency modulation and power adjustment, it makes the reactive current on the control main circuit small, the reactive power is small, and the power factor is high, which greatly saves electric energy. At the same time, it also reduces the harmonic pollution of reactive power to the grid; the use of PI regulator-based rectifier bridge trigger control and intelligent self-adaptive constant power dual-control adjustment strategy ensures the accuracy and stability of heating power at each gear ; The intelligent soft-start control technology adopted improves the safety of the circuit; the intelligent pot detection technology adopted reduces electromagnetic radiation and electromagnetic pollution, and saves electric energy; the hardware dead zone circuit adopted enhances the safety and stability of the electromagnetic cooker. The invention breaks through the limitation of the output power of the traditional electromagnetic cooker, and expands the output power of the double-tube half-bridge electromagnetic cooker to 6000-10000 watts. The firepower control of the induction cooker is precise and stable, and the power factor of the load circuit is high, which greatly saves electric energy. At the same time, it can minimize the harmonic pollution of the equipment to the power grid, and is suitable for various kitchens and restaurants.

Description of drawings

To provide a further understanding of the invention, the accompanying drawings, which constitute a part of this specification, illustrate embodiments of the invention and serve to explain the principles of the invention.

Fig. 1 is a block diagram of the overall structure of the present invention.

Fig. 2 is a circuit diagram of the hardware dead zone control of the present invention.

Fig. 3 is a schematic block diagram of rectification trigger control and intelligent self-adaptive constant power control of the PI regulator of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but these embodiments should not be construed as limiting the present invention.

The main part of the present invention is composed of a controllable rectification filter module (AC-DC module), an inverter module (DC-AC module) and a microcomputer control module (Micro-computer control module) components (as shown in Figure 1); the controllable rectification The filter module rectifies the three-phase alternating current into an adjustable direct current voltage, and then converts the direct current into high-frequency alternating current through the inverter module, and converts the electric energy into electromagnetic energy through the coil plate L4 to radiate to the bottom of the pot to generate eddy current, due to the thermal effect of the eddy current and Heating the pot, the microcomputer control module is the core of the whole system, which is used to collect data and send control information to each module.

The controllable rectification filter module consists of common mode inductor L1, power supply interference suppression capacitors C1, C2, C3, relay, three-phase controllable rectifier bridge, three-phase rectifier bridge trigger circuit, synchronous transformer, PI regulator 1, differential mode inductor L2 and Composed of L3, DC filter capacitor C4, DC voltage detector UT and DC current detector IT1, the external three-phase power supply is connected to the three-phase common-mode inductor L1 and capacitors C1, C2, and C3 to form a neutral filter. The three-phase power supply is filtered to remove high-frequency interference, the output of the filter is connected to the relay, the output of the relay is connected to the three-phase controllable rectifier bridge, and a synchronous transformer is connected in parallel to output three synchronous voltages U _sA , U _sB , U _sC , connected to the synchronous voltage input terminal of the rectification trigger circuit, the trigger pulse signal controls the thyristor of the rectifier bridge, so that the three-phase controllable rectifier bridge outputs a pulsating DC voltage. Output stable and smooth DC voltage U _DC , under rated voltage, its output average voltage U _DC = 2.34*220cosα, α is firing angle. PI regulator 1 outputs the phase-shift control voltage U _C according to the deviation between the given voltage and the feedback voltage, and the phase-shift control voltage is connected to the phase-shift voltage input terminal of the trigger circuit module of the rectifier bridge to control the trigger angle α of the trigger pulse, so that the rectifier The bridge outputs a controllable and stable DC voltage. On the DC bus after the rectification and filtering circuit, a DC voltage detector UT and a DC current detection IT1 are connected. The signal detected by UT is divided into two circuits, and one circuit is used as a voltage feedback signal. After comparing with a given voltage, it is output through PI regulator 1. The phase-shift control voltage, the phase-shift control voltage controls the trigger control signal output by the rectification trigger circuit module, and the other channel is connected to the output of the DC current detector IT1 to the signal conditioning circuit of the microcomputer control module, and then connected to the AD sampling unit of the MCU, IT1 And the signal detected by UT is used as the feedback signal of intelligent adaptive constant power control.

The inverter module is composed of a half-bridge high-power switching tube IGBT module, an IGBT isolation drive circuit, a coil disk L4, resonant capacitors C5 and C6, a high-frequency AC current detector IT2 and a cooker. The IGBT isolation drive circuit is connected to the hardware dead zone control circuit of the microcomputer control module, the microcomputer control module outputs the drive frequency, the IGBT isolation drive circuit drives the half-bridge IGBT module to work, and the stable and smooth DC voltage U _DC obtained by the rectification and filtering circuit Inverted into high frequency alternating current. The operating frequency of the inverter circuit is slightly higher than the resonant frequency of the resonant circuit, the load circuit is close to pure resistance, the reactive power is small, the power factor is high, the harmonic pollution to the grid is small, and the electric energy is saved. The coil disk L4 and the resonant capacitors C5 and C6 are connected in series, and the frequency of its resonant point is slightly lower than the lowest frequency of the power switch tube, so that the load is inductive under any working conditions, driven by the high-frequency AC voltage generated by the inverter circuit , There is a high-frequency AC current on the coil plate L4, and the high-frequency AC current generates an alternating electromagnetic field. According to the principle of induction heating, after the pot is placed on the coil plate L4, eddy current heat is generated at the bottom of the pot to convert electrical energy into heat energy Heating the pot, the eddy current heat directly acts on the bottom of the pot, the heat loss is small, the thermal efficiency is high, the energy utilization rate is effectively improved, and the electric energy is saved. The main circuit of the resonant circuit is connected with a high-frequency AC detector IT2, and the output of IT2 is connected to the signal conditioning circuit of the microcomputer control module, and then sent to the MCU, which is fed back to the microcomputer control module as a pan detection control and overcurrent protection control.

The microcomputer control module is composed of a microcontroller MCU, a power supply module, a relay drive circuit, a hardware dead zone control circuit, a signal conditioning circuit, a gear input circuit, a display circuit and a communication interface circuit. The external power supplies power to each circuit of the microcomputer control module after passing through the power module. The relay driving circuit is controlled by the I/O port of the MCU, and the output of the relay driving circuit is connected with the relay group to control the three-phase power relay and the cooling fan relay. DC voltage detector UT, DC current detector IT1, AC current detector IT2, gear input circuit, temperature detector TT1, TT2 are sent to the A/D sampling unit of MCU after passing through the signal conditioning circuit to convert the analog signal into digital Signals are processed computationally. The input of the hardware dead zone control circuit is connected to the output pin of the PWM unit of the MCU, and the hardware dead zone control circuit outputs two complementary drive signals connected to the isolated drive circuit of the IGBT to control the operating frequency of the power switch tube IGBT. The gear input circuit is connected to the A/D sampling module of the MCU after the signal conditioning circuit, and inputs the given power signal of each gear to the MCU, and the MCU fine-tunes the operating frequency of the induction cooker according to the detected DC voltage and DC current. The output power always follows the given power, the adaptive constant power controls the heating power of each gear, and precisely controls the heating power of each gear. The digital tube display circuit is connected to the SPI port of the MCU, and serially transmits data to the digital tube display. The digital tube displays the current working gear, and displays the fault code in the fault state. The indicator circuit is connected to the I/O port of the MCU. , indicating various working states of the induction hob. The communication interface adopts RS-485 bus to realize the real-time online monitoring of the upper computer, which is convenient for debugging and maintenance.

The input of the hardware dead zone control circuit (as shown in Figure 2) is connected to the PWM output pin of the MCU, and the MCU outputs a PWM signal with a duty ratio of 1/2. The PWM signal is first divided into two opposite signals by the inverter , and then delay each signal from low level to high level. When each signal changes from low level to high level, the capacitor CAP1 (the other is CAP2) is charged through the resistor RES1 (the other is RES2), so that the time when the PWM signal changes from low to high is delayed, and the signal changes from high to high. When the level becomes low, the capacitor CAP1 (the other is CAP2) is quickly discharged through the reverse diode DIODE1 (the other is DIODE2), so that the PWM signal is not delayed when it changes from high level to low level, thus obtaining two channels with Dead zone complementary PWM signal, the length of the dead zone time is calculated by the zero state response of the first-order circuit and the threshold level of the high level input of the AND gate circuit, two complementary PWM signals with dead zone and overcurrent, overcurrent The voltage protection signal and the PWM blockade signal output by the I/O of the MCU are sent to the isolated drive module of the IGBT to drive the IGBT to work.

In the embodiment of the present invention, the self-adaptive constant power control method includes two parts. When adjusting within a relatively large power range, the rectification trigger control based on the PI regulator is used to roughly adjust the output power of the electromagnetic cooker; When adjusting in a small range, when the output voltage of the rectifier bridge is stable, the frequency modulation and power adjustment method based on the PI regulator is used to fine-tune the operating frequency of the inverter module IGBT, so that the output power intelligently and adaptively follows the given power of the gear, and is accurate. Control the heating power of each gear (as shown in Figure 3). The control strategy of the rectification trigger circuit based on the PI regulator is as follows: PI regulator 1 outputs the phase-shift control voltage U _C according to the deviation between the given voltage and the feedback voltage, and the phase-shift control voltage is connected to the phase-shift voltage input of the rectifier bridge trigger circuit module The terminal controls the trigger angle of the trigger pulse, so that the rectifier bridge outputs a controllable and stable DC voltage, thereby adjusting the output power of the induction cooker. At the same time, when the grid voltage increases or decreases, the output voltage of the rectifier bridge increases or decreases, and the feedback voltage also increases or decreases. After comparing with the given voltage, the deviation voltage is not zero, thus changing the output of PI regulator 1 The phase-shifting control voltage can adjust the firing angle of the rectifier bridge thyristor, change the output voltage of the rectifier bridge, make the output voltage of the rectifier bridge follow the given voltage, and effectively suppress the influence of grid voltage fluctuations on the output power.

When the DC voltage is stable, the quasi-voltage and current double closed-loop control based on the PI regulator is used to fine-tune the output power of the induction cooker so that the output power follows the given power. Its specific implementation is: input the working gear from the gear input circuit, input the given power P _I signal to the MCU, and the MCU calculates the actual output according to the voltage and current detected by the DC voltage detector UT and the DC current detector IT1 The power P _O is compared with the given power P _I and the actual output power P _O to obtain the power deviation ΔP, and then through the limited PI regulator 2, the output of the PI regulator 2 is sent to the PWM unit in the MCU to fine-tune the PWM waveform Output frequency, the purpose of PI regulator 2 limiting is to ensure that the lowest frequency output by the PWM unit is higher than the resonance point frequency of the resonant circuit, making the load inductive. The PWM unit outputs a single PWM signal and is connected to the external hardware dead zone control circuit to form two complementary drive signals with dead zones. The two complementary drive signals with dead zones are isolated and connected to the IGBT drive module, and the IGBT drive module The output drive signal is connected to the gate-emitter of the half-bridge IGBT module to drive the half-bridge IGBT module to work and adjust the output power so that the output power follows the given power. The pot material, size, and the distance between the coil plate L4 and the pot are important factors that affect the large difference in output power. During the installation process, the installation error of the coil plate L4 leads to differences in output power. The change of the pot material and the pot The change of the size of the tool will also lead to the change of the output power, and there is a difference in the heating power. When the output voltage of the rectifier bridge is stable, the quasi-voltage and current double closed-loop control based on the PI regulator is used to fine-tune the operating frequency of the induction cooker, so that the total output power It follows the given power, which effectively eliminates the power deviation caused by installation errors and the power deviation caused by the size and material changes of the pot, so that the output power always follows the given power, and the heating power is precisely controlled.

In the embodiment of the present invention, the intelligent soft start technology based on PI regulation is adopted to suppress sudden changes in power, achieve soft start of high-power devices, and protect the safety of high-power devices. In the control structure diagram shown in Figure 3, the proportional constant of the PI regulator 1 is set to be small, and the integral time constant is set to be large. Therefore, when the power is turned on and the gear is switched, the proportional constant is small, The integral time constant is large, the existence of deviation and the integral function of PI regulator 1 make the output phase-shift control voltage U _C of PI regulator 1 change slowly, and the trigger angle output by the rectifier trigger circuit module changes slowly, so that the output of the rectifier bridge The voltage changes slowly, the output power will not increase or decrease instantaneously, the current will not change suddenly, and the transient high voltage caused by the sudden change of current will not damage the high-power devices, so as to protect the safe and reliable operation of high-power electronic devices. At the same time, the signal detected by the high-frequency current detector IT2 on the resonant circuit is sent to the microcomputer control module, which is compared with the current comparator after passing through the signal conditioning circuit. When an overcurrent occurs, the comparator outputs an overcurrent signal to the hardware dead zone control circuit, block the driving signal, quickly protect the high-power device from overcurrent, and ensure the safety of the device.

If the induction cooker continues to drive the IGBT to work without a pot, part of the magnetic field will leak out and a lot of electric energy will be wasted. In order to reduce electromagnetic leakage and electromagnetic pollution and save electric energy, in the embodiment of the present invention, a low power consumption intelligent pan detection function is adopted. The MCU controls the PWM unit to output the PWM drive signal intermittently, and the MCU sends a 50ms PWM drive signal every 2s, while at other times, the PWM unit inside the MCU stops working, and at the same time, the MCU outputs a blocking signal to the hardware dead zone control circuit , and simultaneously block two complementary driving signals with dead zones, so that the upper and lower bridge arms of the switching tube are in the off state at the same time. During the sending frequency period, detect the current on the high-frequency current detector IT2 of the main circuit and the current on the DC current detector IT1 on the DC bus, and judge whether there is a pot on the electromagnetic cooker. When the current is greater than a certain set value, it is proved that the pot There is, the induction cooker enters the normal power output to heat the pot, and when the current is less than the set value, it is judged that there is no pot, and the buzzer gives a short beep and the indicator light flashes to indicate that there is no pot. In the normal heating process, when the pot is removed, the current detected by the DC current detector decreases rapidly. When the current is less than a certain set value, it is judged that there is no pot, and it enters the pot detection mode to detect the pot, which is effective It suppresses a large amount of electromagnetic leakage and electromagnetic pollution caused by the MCU continuing to output the driving frequency of the IGBT when the electromagnetic cooker is without a pot, saves electric energy, and improves efficiency.

Finally, it should be noted that the implementation of the present invention is only for illustrating the technical solution rather than limiting. The contents not described in detail in the description of the present invention belong to the prior art known to those skilled in the art.

Claims (9)

1. high-power energy saving electromagnetic stove intelligence controlling device, it comprises controlled rectification filtration module, inversion module and microcomputer controlling module, it is characterized in that:

The controlled rectification filtration module is integrated with the AC power input interface, as the energy input of whole device, carries out the full-bridge controlled rectification through the three phase rectifier trigger control circuit, passes through output interface after the filtering, for inversion module provides DC power supply; Inversion module is the AC power of high frequency by series resonant circuit with the DC power supply inversion, through producing the electromagnetic field of alternation behind the coil panel L4, is radiated to the pan bottom and produces eddy current, utilizes the thermal effect of eddy current to heat pan; Each module of microcomputer controlling module and other links to each other by data wire, detect DC bus-bar voltage in real time, dc bus current, high-frequency ac current, coil panel L4 temperature, movement temperature and gear input signal, and send control command, by microcontroller chip controls PWM unit output single channel pwm signal, the PWM drive signal that obtains the control of two-way band dead band by hardware dead band control circuit is to drive inversion module, wherein: hardware dead band control circuit is by logical circuit and resistance, electric capacity is formed, and the input of hardware dead band control circuit links to each other with the PWM unit output pin of microcontroller (MCU); Hardware dead band control circuit at first is divided into the single channel pwm signal signal of two-way complementation by inverter, when signal uprises level by low level, by resistance electric capacity is charged, the time is delayed when making pwm signal uprise level by low level, signal is during by high level step-down level, electric capacity is not delayed time when making pwm signal by high level step-down level by the backward diode repid discharge, thereby obtains the PWM drive signal of two-way band dead band complementation.

2. a kind of high-power energy saving electromagnetic stove intelligence controlling device as claimed in claim 1, it is characterized in that: the controlled rectification filtration module is by A, B, C input three-phase alternating voltage is through common mode inductance L1, protective tube F1～F3, power supply disturbs and suppresses capacitor C 1～C3, relay, the three-phase controlled rectification bridge, the three phase rectifier trigger bridge circuit, synchrotrans, pi regulator (1), differential mode inductance L2～L3, filter capacitor C4, dc voltage detector UT and direct current detector IT1 constitute, the voltage signal that dc voltage detector UT detects is divided into two-way, one tunnel voltage feedback signal U as rectifier control circuit _b, another road signal U _dBe connected to the signal conditioning circuit of microcomputer controlling module with the output of direct current detector IT1, together as the feedback signal of self-adaption constant power control.

3. a kind of high-power energy saving electromagnetic stove intelligence controlling device as claimed in claim 1 is characterized in that: inversion module is made of high-power switch tube, isolated drive circuit, resonant capacitance C5～C6, alternating current detector IT2 and coil panel L4; The isolated drive circuit drive signal is provided by the PWM drive signal of the band two-way dead band control that produces through hardware dead band control circuit, through the work of isolated drive circuit driver module rear drive power switch pipe; Be serially connected with alternating current detector IT2 on the resonance major loop, the output of IT2 is connected to the signal conditioning circuit of microcomputer controlling module, delivers to microcontroller (MCU) then, detects control and overcurrent protection signal as pan.

4. a kind of high-power energy saving electromagnetic stove intelligence controlling device as claimed in claim 1 is characterized in that: microcomputer controlling module is made of gear input circuit, cooling fan relay drive circuit, three phase mains relay drive circuit, microcontroller (MCU), power module, signal conditioning circuit, hardware dead band control circuit, safety protective circuit, charactron display circuit, sound light alarming circuit and communication interface circuit; External power source provides power supply through each circuit for microcomputer controlling module behind the power module; Fan and three phase mains relay drive circuit are by the I/O mouth control of microcontroller (MCU), and the output of drive circuit links to each other with the relay group; Dc voltage detector UT, direct current detector IT1, alternating current detector IT2, Temperature Detector TT1～TT2 and gear input circuit signal are through inputing to the A/D sampling unit of microcontroller (MCU) behind the signal conditioning circuit; The gear input circuit adopts the mode of resistance series connection dividing potential drop, and the corresponding voltage of each gear is through sending the A/D sampling unit of microcontroller (MCU) to behind voltage follow and the isolating amplifier circuit; The charactron display circuit shows the current work gear of electromagnetic stove, nonserviceables to show failure code down; Module is integrated with communication interface unit, adopts the RS-485 bus communication protocol, realizes remote online monitoring and failure diagnosis.

5. high-power energy saving electromagnetic stove intelligence control method, its control device is by controlled rectification filtration module, inversion module and microcomputer controlling module, its control method is: adopt adaptive constant-power control method, the output voltage by regulating rectifier bridge and the operating frequency of fine setting inversion module reach the purpose of the permanent power output of regulating each gear, wherein:

The controlled rectification filtration module carries out filtering with three-phase alternating-current supply earlier, adopts based on the three phase rectifier triggering control of pi regulator again and carries out full-bridge rectification, obtains stablizing level and smooth direct voltage once more after the filtering, and this voltage is as the input voltage of inversion module;

Inversion module adopts pulse frequency modulated (PFM) method, is AC power by series resonant circuit with the DC power supply inversion, its operating frequency is a little more than the resonance frequency of resonant circuit, control by microcomputer controlling module, make load be perception, ac inverter makes electric energy convert electromagnetic energy to by coil panel L4, and electromagnetic field radiation to pan bottom produces eddy current, because the thermal effect of eddy current produces Joule heat, thus the heating pan;

Microcomputer controlling module detects DC bus-bar voltage, dc bus current, high-frequency ac current, coil panel L4 temperature, movement temperature and gear input signal in real time, after handling as calculated, by microcontroller chip controls PWM unit output single channel pwm signal, the PWM drive signal that obtains the control of two-way band dead band by the hardware dead-zone circuit is to drive inversion module, wherein: hardware dead band control circuit is made up of logical circuit and resistance, electric capacity, and the input of hardware dead band control circuit links to each other with the PWM unit output pin of microcontroller (MCU); Hardware dead band control circuit at first is divided into the single channel pwm signal signal of two-way complementation by inverter, when signal uprises level by low level, by resistance electric capacity is charged, the time is delayed when making pwm signal uprise level by low level, signal is during by high level step-down level, electric capacity is not delayed time when making pwm signal by high level step-down level by the backward diode repid discharge, thereby obtains the PWM drive signal of two-way band dead band complementation.

6. a kind of high-power energy saving electromagnetic stove intelligence control method as claimed in claim 5 is characterized in that: adaptive constant-power control method comprises two parts: when regulating in more high-power scope, adopt and regulate the output of rectifier bridge output voltage adjusting power; When power is regulated in more among a small circle, behind the rectifier bridge output voltage stabilization, adopt the mode of frequency modulation Power Regulation, the operating frequency of isolated drive circuit in the fine setting inversion module, what make the power output intelligent adaptive follows the given power of gear, accurately controls the heating firepower of each gear.

7. a kind of high-power energy saving electromagnetic stove intelligence control method as claimed in claim 5 is characterized in that: controllable rectifier module adopts the three-phase commutation bridge of pi regulator to trigger control, provides the given signal U of three-phase commutation bridge output voltage from the gear input circuit _I, U _IFeedback voltage signal U with the dc voltage detector detection _bCompare, obtain voltage deviation Δ U,, regulate the phase shift controlling voltage U of rectification triggering circuit by pi regulator (1) _CSize changes the trigger angle of three-phase commutation bridge thyristor, thereby adjusts the output voltage of three-phase controlled rectification bridge, changes the power output of electromagnetic stove.

8. a kind of high-power energy saving electromagnetic stove intelligence control method as claimed in claim 5; it is characterized in that: adopt soft-start method: the control strategy of regulating based on PI is all adopted in rectifier and trigger control circuit and the control of permanent power; when starting up and gear shift; the voltage of rectifier bridge output slowly changes and the power of electromagnetic stove output slowly changes; suppress the sudden change of electric current in the main circuit; accomplish the soft start of high power device, the safety of protection high power device.

9. a kind of high-power energy saving electromagnetic stove intelligence control method as claimed in claim 5, it is characterized in that: adopt the pan of low-power consumption to detect control method, electromagnetic stove is under inspection pot state, adopt intermittent duty to send inspection pot pulse signal, sending stopping period, forbid the power switch pipe work in the inversion module, and, make the upper and lower brachium pontis of isolated drive circuit module be in off state simultaneously by microcontroller chip output PWM locking signal.

Images