WO2023109916A1

WO2023109916A1 - Power control circuit and power control method for electromagnetic heating device

Info

Publication number: WO2023109916A1
Application number: PCT/CN2022/139374
Authority: WO
Inventors: 左远洋; 胡建; 侯俊峰; 冯江平
Original assignee: 广东美的白色家电技术创新中心有限公司; 美的集团股份有限公司
Priority date: 2021-12-17
Filing date: 2022-12-15
Publication date: 2023-06-22
Also published as: CN114390737A; CN114390737B

Abstract

The present application discloses a power control circuit and a power control method for an electromagnetic heating device. The power control circuit comprises: a resonant circuit; a control circuit, connected to the resonant circuit and configured to control the resonant circuit to work on the basis of a power control signal; and a detection circuit, connected to a resonant loop of the resonant circuit, connected to the control circuit, and configured to detect an output power of the resonant loop. The control circuit is further configured to adjust the power control signal on the basis of the output power and a target power of the resonant circuit, so as to control the resonant circuit to work by using the adjusted power control signal. In this way, the power control accuracy of the electromagnetic heating device can be improved.

Description

Power control circuit and power control method of electromagnetic heating device

This application claims the priority of the Chinese patent application with the application number 2021115552635 filed on December 17, 2021, entitled "Power Control Circuit and Power Control Method for Electromagnetic Heating Device", which is fully incorporated by reference into this application.

【Technical field】

The present application relates to the technical field of electromagnetic heating, in particular to a power control circuit and a power control method of an electromagnetic heating device.

【Background technique】

The electromagnetic heating device realizes electromagnetic heating based on the alternating magnetic field of the resonant circuit. When the power supply characteristics of the resonant circuit change, the power of electromagnetic heating, etc. will change, and the effective electromagnetic heating function cannot be realized.

In order to solve the above problems, in the prior art, the (power supply) bus voltage and the (power supply) bus current are sampled, and the total input power of the resonant circuit is obtained based on the bus voltage and the bus current, so as to realize the resonant circuit. Output power monitoring. However, in this way, the output power of each resonant tank in the resonant circuit cannot be monitored, so the power control accuracy is low.

【Content of invention】

The technical problem mainly solved by the present application is to provide a power control circuit and a power control method of an electromagnetic heating device, which can improve the precision of power control of the electromagnetic heating device.

In order to solve the above technical problems, a technical solution adopted by the present application is to provide a power control circuit of an electromagnetic heating device. The power control circuit includes: a resonant circuit; a control circuit, connected to the resonant circuit, to control the operation of the resonant circuit based on a power control signal; a detection circuit, connected to the resonant circuit of the resonant circuit, and connected to the control circuit, for detecting the resonant circuit Output power; the control circuit is further used to adjust the power control signal based on the output power and the target power of the resonant circuit, so as to use the adjusted power control signal to control the resonant circuit to work.

In one embodiment, the resonant circuit includes: a coil whose first end is connected to the detection circuit and the control circuit; a resonant capacitor whose first end is connected to the second end of the coil and whose second end is connected to the detection circuit.

In one embodiment, the power control circuit includes at least two resonant circuits, at least two detection circuits, and at least two control circuits; the first end of the coil of a resonant circuit is connected with a detection circuit and a control circuit, and a resonant circuit The first end of the resonant capacitor is connected to the second end of the coil of a resonant circuit, the second end of the resonant capacitor of a resonant circuit is connected to a detection circuit; the first end of the coil of the other resonant circuit is connected to another detection circuit connected to another control circuit, the first end of the resonant capacitor of the other resonant circuit is connected to the second end of the coil of the other resonant circuit, and the second end of the resonant capacitor of the other resonant circuit is connected to another detection circuit.

In one embodiment, the detection circuit includes: a voltage sampling circuit, whose first acquisition end is connected to the first end of the coil, and whose output end is connected to the control circuit, for collecting the resonant voltage of the resonant circuit; a current sampling circuit, whose second A collection terminal is connected to the second terminal of the resonance capacitor, its second collection terminal is connected to the second collection terminal of the voltage sampling circuit, and its output terminal is connected to the control circuit for collecting the resonance current of the resonance circuit; the control circuit is based on the resonance voltage And the resonant current to calculate the output power of the resonant tank.

In one embodiment, the control circuit includes: a power regulation circuit, the input terminals of which are respectively connected to the second terminal of the voltage sampling circuit and the second terminal of the current sampling circuit, for calculating the output power of the resonant circuit based on the resonant voltage and resonant current , and adjust the power control signal based on the output power and the target power; the switch tube, its control end is connected to the power adjustment circuit, and its communication end is connected to the second end of the coil, which is used to turn on and off under the control of the power control signal, To adjust the output power of the resonant tank.

In order to solve the above technical problems, a technical solution adopted by the present application is to provide a power control method of an electromagnetic heating device. The power control method is used in the above power control circuit, and the power control method includes: obtaining the output power of the resonant circuit of the resonant circuit; comparing the output power with the target power of the resonant circuit; adjusting the power control signal based on the comparison result, so as to utilize the adjustment The latter power control signal controls the resonant circuit to work.

In one embodiment, the acquisition of the output power of the resonant circuit of the resonant circuit includes: obtaining the sampling period; setting a plurality of sampling points within the sampling period, and obtaining the resonant voltage and resonant current of the resonant circuit corresponding to the sampling points; The average power of the resonant circuit in the sampling period is calculated as the output power by calculating a resonant voltage and a plurality of resonant currents.

In an embodiment, the above-mentioned adjusting the power control signal based on the comparison result includes: adjusting the frequency of the power control signal based on the comparison result.

In one embodiment, adjusting the frequency of the power control signal based on the comparison result includes: increasing the frequency of the power control signal in response to the output power being greater than the target power; decreasing the frequency of the power control signal in response to the output power being less than the target power.

In an embodiment, the above-mentioned adjusting the power control signal based on the comparison result includes: adjusting the duty cycle of the power control signal based on the comparison result.

In an embodiment, the above-mentioned adjusting the power control signal based on the comparison result includes: adjusting the frequency and duty cycle of the power control signal based on the comparison result.

The beneficial effects of the embodiments of the present application are: the power control circuit of the electromagnetic heating device of the present application includes: a resonant circuit; a control circuit connected to the resonant circuit, based on a power control signal to control the work of the resonant circuit; a detection circuit connected to the resonant circuit of the resonant circuit and connected with the control circuit for detecting the output power of the resonant circuit; the control circuit is further used for adjusting the power control signal based on the output power and the target power of the resonant circuit, so as to use the adjusted power control signal to control the resonant circuit to work. The application can detect the output power of the resonant circuit through the detection circuit connected in the resonant circuit of the resonant circuit, and adjust the power control signal of the control circuit through the control circuit based on the output power of the resonant circuit and the target power, and use the adjusted power control signal Controlling the work of the resonant circuit can not only keep the output power of the resonant circuit following its target power, and realize effective electromagnetic heating function, but also can directly and independently monitor the output power of (each) resonant circuit, and the output power of (each) resonant circuit The power is controlled independently, so the accuracy of power control can be improved.

【Description of drawings】

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present application. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is the structural diagram of the power control circuit of electromagnetic heating device;

Fig. 2 is a structural diagram of the power control circuit of the electromagnetic heating device;

Fig. 3 is a structural schematic diagram of an embodiment of the power control circuit of the electromagnetic heating device of the present application;

Fig. 4 is a schematic flow chart of an embodiment of a power control method for an electromagnetic heating device of the present application;

Fig. 5 is a structural schematic diagram of an embodiment of the power control circuit of the electromagnetic heating device of the present application;

Fig. 6 is a schematic flow chart of an embodiment of a power control method for an electromagnetic heating device of the present application;

FIG. 7 is a schematic flowchart of step S61 in the embodiment of FIG. 6 .

【Detailed ways】

The application will be described in further detail below in conjunction with the accompanying drawings and embodiments. In particular, the following examples are only used to illustrate the present application, but not to limit the scope of the present application. Likewise, the following embodiments are only some of the embodiments of the present application but not all of them, and all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

In the description of the embodiments of this application, it should be noted that unless otherwise specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection, Or integrated connection; it can be mechanical connection or electrical connection; it can be direct connection or indirect connection through an intermediary. Those of ordinary skill in the art can understand the specific meanings of the above terms in the embodiments of the present application in specific situations.

In the embodiment of the present application, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first feature and the second feature may pass through the middle of the second feature. Media indirect contact. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structures, materials or features are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

In order to realize the monitoring and control of the output power of the resonant circuit, the control circuit respectively controls the voltage detection circuit to collect the voltage of the power supply bus and controls the current detection circuit to collect the current of the power supply bus circuit, as shown in Figure 1, based on the current and voltage to obtain the resonance The total power input to the circuit.

Since the electromagnetic heating device realizes electromagnetic heating based on the alternating magnetic field of the coil in the resonant circuit, the (heating) power of the electromagnetic heating device is approximately equivalent to the power consumption of the coil. Since the current of the power supply bus circuit is not the current of the resonant circuit, and the voltage of the power supply bus is not the voltage of the resonant circuit, the total input power cannot directly reflect the output power of the resonant circuit, let alone the power consumption of the coil in the resonant circuit. The power of the electromagnetic heating device cannot be accurately controlled.

Furthermore, in the application scenario shown in Figure 2, the power obtained from the voltage of the power supply busbar and the current of the power supply busbar circuit is the total input power, which cannot reflect the output power of each resonant circuit in multiple resonant circuits, let alone It reflects the power consumption of the coils in each resonant circuit, so the power consumption of each coil cannot be controlled separately based on the total input power.

In order to solve the above problems, the present application first proposes a power control circuit of an embodiment of an electromagnetic heating device, as shown in FIG. 3 , which is a schematic structural diagram of an embodiment of a power control circuit of an electromagnetic heating device of the present application. The power control circuit (not marked) of the present embodiment includes: a resonant circuit 31, a control circuit 32 and a detection circuit 33; wherein the control circuit 32 is connected to the resonant circuit 31, and the resonant circuit 31 is controlled to work based on a power control signal; the detection circuit 33 Connected in the resonant circuit of the resonant circuit 31, and connected with the control circuit 32, for detecting the output power of the resonant circuit; the control circuit 32 is further used for adjusting the power control signal based on the target power of the resonant circuit output power and the resonant circuit 31, to The adjusted power control signal is used to control the resonant circuit 31 to work.

The control circuit 32 controls the detection circuit 33 to periodically collect the output power of the resonant circuit, compares the output power of the resonant circuit with the target power, adjusts the power control signal according to the comparison result, and controls the resonant circuit 31 using the adjusted power control signal Work to adjust the output power of the resonant circuit as close as possible to the target power, so that the electromagnetic heating device can realize effective electromagnetic heating function.

Specifically, if the control circuit 32 determines that the output power of the resonant tank is greater than the target power, then increase the frequency of the power control signal and/or reduce the duty cycle of the power control signal to reduce the output power of the resonant tank and enter the next sampling period ; If the control circuit 32 determines that the output power of the resonant tank is less than the target power, then reduce the frequency of the power control signal and/or increase the duty cycle of the power control signal to increase the output power of the resonant tank and enter the next sampling cycle; The circuit 32 determines that the output power of the resonant tank is equal to the target power, then keeps the power control signal unchanged, and enters the next sampling period.

In this embodiment, the output power of the resonant circuit can be detected by the detection circuit 33 connected to the resonant circuit of the resonant circuit 31, and the power control signal of the control circuit 32 can be adjusted by the control circuit 32 based on the output power of the resonant circuit and the target power. The final power control signal controls the resonant circuit 31 to work, not only can make the output power of the resonant circuit keep following its target power, realize effective electromagnetic heating function, and can directly monitor the output power of (each) resonant circuit independently, to (each 1) The output power of the resonant tank is independently controlled, so the accuracy of power control can be improved.

Optionally, the resonant circuit 31 of this embodiment includes: a coil L and a resonant capacitor C; wherein, the first end of the coil L is connected to the detection circuit 33 and the control circuit 32; the first end of the resonant capacitor C is connected to the second end of the coil L The two terminals are connected, and the second terminal of the resonant capacitor C is connected to the detection circuit 33 .

The resonant circuit 31 of this embodiment is a series resonant circuit composed of a coil L and a resonant capacitor C. In other embodiments, the resonant circuit may also be a parallel resonant circuit, and the technical effect of this embodiment can also be achieved by properly adjusting the circuit structure.

Optionally, the detection circuit 33 of this embodiment includes: a voltage sampling circuit 331 and a current sampling circuit 332; wherein, the first acquisition terminal of the voltage sampling circuit 331 is connected to the first terminal of the coil L, and the output terminal of the voltage sampling circuit 331 Connect with the control circuit 32, the voltage sampling circuit 331 is used to collect the resonant voltage of the resonant circuit; the first collection end of the current sampling circuit 332 is connected with the second end of the resonant capacitor C, the second collection end of the current sampling circuit 332 is connected with the voltage sampling The second collection terminal of the circuit 331 is connected, the output terminal of the current sampling circuit 332 is connected with the control circuit 32, and the current sampling circuit 332 is used for collecting the resonance current of the resonance circuit. The control circuit 32 calculates the output power of the resonance tank based on the resonance voltage and the resonance current.

In an application scenario, the output power may be the average power of the resonant tank. Specifically, the control circuit 32 sets N sampling points in each sampling period. The larger N is, the higher the sampling accuracy is; The resonant voltage of the resonant circuit is recorded as v(k); the control circuit 32 controls the current sampling circuit 332 to collect the resonant current of the resonant circuit at corresponding N sampling points in each sampling period, that is, the current of the coil L, and is recorded as i( k).

Because the resonant capacitor C loses very little, the power lost relative to the coil L (including the heating energy of electromagnetic heating) can be ignored. Then the power lost by the coil L in each sampling period is:

Among them, T is the time length of each sampling cycle. When the bus voltage is a constant voltage, T can be the working cycle of the half bridge; when the bus voltage is a non-constant voltage, T is the fluctuation period of the bus voltage. For example, the AC is 50Hz alternating current, after rectification, the frequency of the bus voltage fluctuation is 100Hz, and the period is 10ms, then T is the fluctuation period of the bus voltage, that is, 10ms. From the beginning of each sampling period, samples are taken at intervals of T/N. And in the sampling period of each half-bridge, at least 100 samples are taken; the average power of each sampling period is: P=E/T.

In this embodiment, the fluctuation period of the bus voltage is used as the sampling period, and the average power of each sampling period is calculated, which can suppress excessive control fluctuations caused by instantaneous power fluctuations.

In other application scenarios, the time length of the sampling period and the number of sampling points can be adjusted.

In this embodiment, the power control is performed by using the sampling period and its average power, which can avoid frequent adjustment of the power control signal.

In other embodiments, other methods are used to calculate the average power of the resonant tank, or other powers of the resonant tank are used instead of the average power.

For example, the resonant current and resonant voltage of the resonant circuit can be sampled at a preset time interval, and the output power of the sampling point can be obtained, and the power control signal can be adjusted based on the output power. In this way, the average power does not need to be calculated, and the calculation can be simplified, and The output power of the resonant circuit can be adjusted in real time.

The adjustment amount of the power control signal can be a preset amount, or can be obtained based on the difference between the output power of the resonant tank and the target power.

Wherein, the voltage sampling circuit 331 may be a resistor or the like, and the current sampling circuit 332 may be a current transformer or the like.

Optionally, the control circuit 32 of this embodiment includes: a power regulation circuit 321 and a switch tube (not shown); wherein, the input terminal of the power regulation circuit 321 is connected to the second terminal of the voltage sampling circuit 331 and the current sampling circuit 332 respectively. The second terminal connection of the voltage sampling circuit 331 is used to calculate the output power of the resonant circuit based on the resonant voltage of the voltage sampling circuit 331 and the resonant current of the current sampling circuit 332, and adjust the power control signal based on the output power of the resonant circuit and the target power; the control of the switching tube The end is connected to the power regulating circuit 321, the communication end of the switch tube is connected to the second end of the coil L, and the switch tube is used to turn on and off under the control of the power control signal to adjust the output power of the resonant circuit.

The power regulating circuit 321 controls the switching tube to be turned on and off periodically through the power control signal, and the coil L is charged and oscillatingly discharged in each cycle, which can generate a high-frequency changing magnetic field to heat food by electromagnetic induction.

The control circuit 32 of this embodiment further includes a driving circuit 322, which is respectively connected to the control terminal of the power regulating circuit 321 and the switching tube, and is used to increase the driving force of the power regulating circuit 321 on the switching tube to ensure the normal operation of the switching tube.

Wherein, the control circuit 32 of this embodiment includes a switch tube Q1 and a switch tube Q2, and the switch tube Q1 and the switch tube Q2 form a half-bridge inverter circuit. The first communication terminal of the switch tube Q1 is connected to the first power supply terminal, the second communication terminal of the switch tube Q1 is connected to the first communication terminal of the switch tube Q2, the second communication terminal of the switch tube Q2 is connected to the second power supply terminal, and the switch The control terminal of the tube Q1 and the control terminal of the switching tube Q2 are connected to the driving circuit 322 .

In an application scenario, as shown in FIG. 4 , after entering the power control, first, the power regulation circuit 321 outputs a power control signal of a fixed frequency to the drive circuit 322, and the drive circuit 322 drives the switch tube Q1 and the switch at the fixed frequency. The tube Q2 is turned on alternately, so that the square wave voltage is applied to the coil L and the resonant capacitor C, and the coil L starts to generate current and consume energy; starting at time 0 of each sampling period, the voltage sampling circuit 331 takes an interval of T/N The resonant voltage of the resonant circuit is continuously sampled, and the current sampling circuit continuously samples the resonant current of the resonant circuit at an interval of T/N until the end of a sampling period; the power adjustment circuit 321 calculates the average power P of a sampling period just ended, and calculates The difference between the average power and the target power; if the difference > 0, it means that the output power is too large, and then output the frequency of increasing the power control signal; if the difference = 0, it means that the output power has reached the target power, Then keep the frequency of the power control signal unchanged; if the difference is <0, it means that the output power is too small, then reduce the frequency of the output power control signal; repeat the above steps in the power control stage, so that the output power of the resonant circuit is always Keep following your target power.

The switch tube in this embodiment is an N-MOS tube, its control terminal is a gate, its first communication terminal is a drain, and its second communication terminal is a source.

In other embodiments, switch tubes such as relays, thyristors, or IGBTs can be used instead of N-MOS tubes; or P-MOS tubes can be used instead of N-MOS tubes, and the circuit structure of this embodiment is adaptively adjusted to achieve The technical effect of this embodiment is realized.

Wherein, the power adjustment circuit 321 of this embodiment may be an integrated circuit chip, which has signal processing capabilities. The power regulation circuit 321 can also be a general processor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, and discrete hardware components. The general processor can be a microprocessor or the power regulation circuit 321 can also be any conventional processor or the like. Wherein, the power regulating circuit 321 may be integrated in the hardware of the switching power supply, or in the powered equipment.

Optionally, the power control circuit of this embodiment further includes: a rectifier circuit 34, which is respectively connected to the AC power source AC and the switching tube, and is used to rectify the AC power input by the AC power source AC to obtain DC power, and supply the DC power to the switch Tube.

Wherein, the rectifier circuit 34 is a full-bridge rectifier circuit, including a first diode (not marked), a second diode (not marked), a third diode (not marked) and a fourth diode (figure not marked); the cathode of the first diode is connected to the cathode of the third diode, and the anode of the first diode is connected to the cathode of the second diode and the first power supply end of the alternating current power supply AC; the fourth two The cathode of the pole tube is connected to the anode of the third diode and the second power supply end of the AC power supply AC, the anode of the fourth diode is connected to the anode of the second diode; the cathode of the third diode is connected to the switch tube Q1 The first communication terminal and the anode of the fourth diode are connected to the second communication terminal of the switching transistor Q2.

The rectifier circuit 34 converts the input alternating current by simultaneously turning on the first diode and the fourth diode and simultaneously cutting off the second diode and the third diode, or by simultaneously turning off the first diode and the fourth diode. The diode and the second diode and the third diode are simultaneously turned on to convert the alternating current into direct current.

In other embodiments, transistors or field effect transistors may be used instead of the above-mentioned diodes, or other circuits such as half-bridge rectifier circuits may be used instead of the above-mentioned full-bridge rectifier circuit.

In other embodiments, a DC power supply may be used to power the electromagnetic resonance control circuit without setting a rectification circuit.

Optionally, the power control circuit of this embodiment further includes: a filter circuit (not shown in the figure), which is respectively connected to the rectifier circuit and the switching tube, and is used to filter the direct current, which can filter out the AC clutter in the direct current, and Provided to the switch tube. Specifically, the filter circuit in this embodiment is a filter capacitor.

In another embodiment, as shown in FIG. 5 , the power control circuit of this embodiment is provided with two resonant circuits, which can realize independent detection and control of the output power of each resonant circuit. Specifically, the power control circuit of this embodiment includes two resonant circuits 31, two detection circuits 33 and two control circuits 32; the first end of the coil L of a resonant circuit 31 and a detection circuit 33 and a control circuit 33 Connect, the first end of the resonant capacitor C of a resonant circuit 31 is connected with the second end of the coil L of a resonant circuit 31, the second end of the resonant capacitor C of a resonant circuit 31 is connected with a detection circuit 33; The first end of the coil L of the circuit 31 is connected to another detection circuit 33 and another control circuit 32, and the first end of the resonant capacitor C of the other resonant circuit 31 is connected to the second end of the coil L of the other resonant circuit 31 , the second end of the resonant capacitor C of the other resonant circuit 31 is connected to another detection circuit 33 .

The specific connection circuit between the resonant circuit 31 and the corresponding detection circuit 33 of this embodiment can refer to the above embodiments, and other circuit structures of the power control circuit of this embodiment can also refer to the above embodiments.

In this embodiment, different power regulating circuits 321 are used to control the two resonant circuits 31 . Of course, in other embodiments, the same power regulating circuit 321 may be used to control the resonant circuits and corresponding detection circuits respectively.

In other embodiments, multiple resonant circuits can be set in the electromagnetic heating device to form multiple resonant circuits, and multiple detection circuits and multiple control circuits. For each resonant circuit, a corresponding detection circuit is used for power detection, and a The corresponding control circuit is controlled.

Certainly, the above-mentioned detection circuit of the present application can also be used for power detection for each resonant circuit, and multiple resonant circuits can share a control circuit, a power supply circuit, and the like.

The electromagnetic heating device of the present application may be heating devices such as an electromagnetic rice cooker, an electromagnetic oven, an electromagnetic pressure cooker, and an electromagnetic oven.

The present application further proposes a power control method of an electromagnetic heating device, which can be used in the heating control circuit of the above embodiment, as shown in FIG. 6 , which is a schematic flowchart of an embodiment of a power control method of an electromagnetic heating device of the present application. The power control method in this embodiment specifically includes the following steps:

Step S61: Obtain the output power of the resonant tank of the resonant circuit.

The control circuit controls the detection circuit to collect the output power of the resonant tank periodically.

The output power of the resonant circuit can reflect the power consumption of the coil in the resonant circuit, that is, the heating power of the electromagnetic heating device.

Optionally, in this embodiment, the method shown in FIG. 7 may be used to implement step S61. The method of this embodiment specifically includes step S71 to step S73:

Step S71: Obtain a sampling period.

Step S72: setting a plurality of sampling points in the sampling period, and obtaining the resonance voltage and the resonance current of the resonance circuit corresponding to the sampling points.

Step S73: Calculate the average power of the resonant circuit within the sampling period based on the multiple resonant voltages and multiple resonant currents as the output power.

Introduce step S71 to step S73 together:

The control circuit sets N sampling points in each sampling period. The larger N is, the higher the sampling accuracy is; the control circuit controls the voltage sampling circuit to collect the resonant voltage of the resonant circuit at the corresponding N sampling points in each sampling period, and record is v(k); the control circuit controls the current sampling circuit to collect the resonant current of the resonant circuit at the corresponding N sampling points in each sampling period, that is, the current of the coil L, and it is recorded as i(k).

Step S62: Comparing the output power with the target power of the resonant circuit.

The control circuit acquires the difference between the output power and the target power.

Step S63: Adjust the power control signal based on the comparison result, so as to control the resonant circuit to work by using the adjusted power control signal.

If the difference is greater than zero, adjust the power control signal to reduce the output power of the resonance circuit; if the difference is less than zero, adjust the power control signal to increase the output power of the resonance circuit; if the difference is equal to zero, keep the output power of the resonance circuit constant Change.

In this embodiment, the power consumed by the resonant circuit and the output power are independently detected, so that the power consumed by each coil in the power control circuit can be independently controlled.

This application can detect the output power of the resonant circuit, and adjust the power control signal of the control circuit through the comparison result of the output power and the target power, and use the adjusted power control signal to control the resonant circuit to work, not only can the output power of the resonant circuit keep following Its target power realizes effective electromagnetic heating function, and can directly and independently monitor the output power of (each) resonant circuit, and independently control the output power of (each) resonant circuit, so the accuracy of power control can be improved.

Optionally, in this embodiment, the frequency of the power control signal may be adjusted based on the comparison result. Specifically, in response to the output power being greater than the target power, increasing the frequency of the power control signal increases the impedance of the resonant circuit, thereby reducing the resonant current of the resonant circuit, thereby reducing the output power of the resonant circuit; in response to the output power being less than the target Power, reduce the frequency of the power control signal, so that the impedance of the resonant circuit decreases, so that the resonant current of the resonant circuit increases, and then the output power of the resonant circuit increases; in response to the output power being equal to the target power, keep the frequency of the power control signal unchanged .

In another embodiment, the duty cycle of the power control signal may also be adjusted based on the comparison result. In response to the output power being greater than the target power, reduce the duty cycle of the power control signal, so that the voltage of the resonant circuit decreases, thereby reducing the output power of the resonant circuit; in response to the output power being less than the target power, increase the duty cycle of the power control signal Ratio, so that the voltage of the resonant tank increases, so that the output power of the resonant tank increases; in response to the output power being equal to the target power, the duty cycle of the power control signal is kept constant.

In another embodiment, the frequency and duty cycle of the power control signal can also be adjusted based on the comparison result. The adjustment principle can be combined with the above frequency and duty cycle adjustment methods.

The present application can adopt the above-mentioned similar power control method for each resonant circuit in the power control circuit with multiple resonant circuits, to detect the power inside each resonant circuit, and realize the power of each coil (or each independent control of the output power of the half-bridge).

Different from the prior art, the power control circuit of the electromagnetic heating device of the present application includes: a resonant circuit; a control circuit connected to the resonant circuit, based on a power control signal to control the operation of the resonant circuit; a detection circuit connected to the resonant circuit of the resonant circuit, and Connected with the control circuit for detecting the output power of the resonant circuit; the control circuit is further used for adjusting the power control signal based on the output power and the target power of the resonant circuit, so as to use the adjusted power control signal to control the resonant circuit to work. The application can detect the output power of the resonant circuit through the detection circuit connected in the resonant circuit of the resonant circuit, and adjust the power control signal of the control circuit through the control circuit based on the output power of the resonant circuit and the target power, and use the adjusted power control signal Controlling the work of the resonant circuit can not only keep the output power of the resonant circuit following its target power, and realize effective electromagnetic heating function, but also can directly and independently monitor the output power of (each) resonant circuit, and the output power of (each) resonant circuit The power is controlled independently, so the accuracy of power control can be improved.

The above is only the implementation of the application, and does not limit the patent scope of the application. Any equivalent mechanism or equivalent process conversion made by using the specification and drawings of the application, or directly or indirectly used in other related technologies fields, are all included in the scope of patent protection of this application in the same way.

Claims

A power control circuit of an electromagnetic heating device, characterized in that it comprises:

resonant circuit;

A control circuit, connected to the resonant circuit, controls the resonant circuit to work based on a power control signal;

A detection circuit connected to the resonant circuit of the resonant circuit and connected to the control circuit for detecting the output power of the resonant circuit;

The control circuit is further configured to adjust the power control signal based on the output power and the target power of the resonant circuit, so as to use the adjusted power control signal to control the resonant circuit to work.
The power control circuit according to claim 1, wherein the resonant circuit comprises:

a coil, the first end of which is connected to the detection circuit and the control circuit;

A resonant capacitor, the first end of which is connected to the second end of the coil, and the second end of which is connected to the detection circuit.
The power control circuit according to claim 2, wherein the power control circuit comprises at least two of the resonant circuits, at least two of the detection circuits and at least two of the control circuits;

A first end of a coil of the resonant circuit is connected to a detection circuit and a control circuit, and a first end of a resonant capacitor of the resonant circuit is connected to a coil of the resonant circuit. The second end is connected, and the second end of the resonant capacitor of the one said resonant circuit is connected to said one said detection circuit;

The first end of the coil of the other resonant circuit is connected to the other detection circuit and the other control circuit, and the first end of the resonant capacitor of the other resonant circuit is connected to the other said resonant circuit. The second end of the coil of the resonant circuit is connected, and the second end of the resonant capacitor of the other resonant circuit is connected with the other detection circuit.
The power control circuit according to claim 2 or 3, wherein the detection circuit comprises:

A voltage sampling circuit, the first acquisition end of which is connected to the first end of the coil, and its output end is connected to the control circuit, for collecting the resonance voltage of the resonance circuit;

A current sampling circuit, the first collection terminal of which is connected to the second terminal of the resonant capacitor, the second collection terminal of which is connected to the second collection terminal of the voltage sampling circuit, and the output terminal thereof is connected to the control circuit, for collecting the resonance current of the resonance circuit;

The control circuit calculates the output power of the resonance tank based on the resonance voltage and the resonance current.
The power control circuit according to claim 4, wherein the control circuit comprises:

A power regulating circuit, the input terminals of which are respectively connected to the second terminal of the voltage sampling circuit and the second terminal of the current sampling circuit, for calculating the output power of the resonant circuit based on the resonant voltage and the resonant current , and adjusting the power control signal based on the output power and the target power;

A switch tube, the control end of which is connected to the power regulating circuit, and the communication end of which is connected to the second end of the coil, is used to turn on and off under the control of the power control signal, so as to adjust the resonant circuit Output Power.
A power control method for an electromagnetic heating device, characterized in that it is used in the power control circuit according to any one of claims 1 to 5, the power control method comprising:

obtaining the output power of the resonant circuit of the resonant circuit;

comparing the output power with a target power for the resonant circuit;

The power control signal is adjusted based on the comparison result, so that the resonant circuit is controlled to work by using the adjusted power control signal.
The power control method according to claim 6, wherein the obtaining the output power of the resonant circuit of the resonant circuit comprises:

Get the sampling period;

Setting a plurality of sampling points within the sampling period, and obtaining the resonance voltage and resonance current of the resonance circuit corresponding to the sampling points;

calculating the average power of the resonant circuit within the sampling period based on the plurality of resonant voltages and the plurality of resonant currents to be the output power.
The power control method according to claim 6, wherein the adjusting the power control signal based on the comparison result comprises:

The frequency of the power control signal is adjusted based on the comparison.
The power control method according to claim 8, wherein the adjusting the frequency of the power control signal based on the comparison result comprises:

increasing the frequency of the power control signal in response to the output power being greater than the target power;

The frequency of the power control signal is decreased in response to the output power being less than the target power.
The power control method according to claim 6, wherein the adjusting the power control signal based on the comparison result comprises:

A duty cycle of the power control signal is adjusted based on the comparison.
The power control method according to claim 6, wherein the adjusting the power control signal based on the comparison result comprises:

The frequency and duty cycle of the power control signal are adjusted based on the comparison result.