Transistor control circuit and control method thereof, heating circuit and cooking appliance

Abstract

The present invention provides a transistor control circuit and a control method thereof, a heating circuit, and a cooking appliance. The control circuit includes: a resonant circuit, an insulated gate bipolar transistor, a sampling circuit, a master control circuit, and a drive circuit, wherein the master control circuit is further connected to the resonant circuit via a switch circuit, and is used to control the switch circuit to disconnect when the rate of change of the electrical parameters of the insulated gate bipolar transistor sampled by the sampling circuit exceeds a preset rate of change threshold, so as to adjust the capacitance value of the resonant circuit. As a result, when the capacitance value of the resonant circuit changes, the charging time of the capacitor in the resonant circuit in each subsequent resonant cycle also changes accordingly. In this way, the hard turn-on phenomenon of the insulated gate bipolar transistor can be eliminated. As a result, the temperature of the insulated gate bipolar transistor is avoided from being too high, the probability of damage to the insulated gate bipolar transistor is effectively reduced, and the working reliability and life of the related products are improved.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to an insulated gate bipolar transistor control circuit, an electromagnetic heating circuit, a cooking appliance, and an insulated gate bipolar transistor control method. Background Art

[0002] Currently, insulated-gate bipolar transistor (IGBT) control circuits are widely used in various electrical appliances. For example, there are many cooking appliances on the market that use electromagnetic heating technology, such as rice cookers and electric pressure cookers. The operating principle of these cooking appliances is to use a drive circuit to send a pulse signal of a certain frequency to the IGBT, so that the IGBT can be turned on or off in response to the pulse signal. When the IGBT is turned on, the resonant circuit in the cooking appliance is charged. When the IGBT is turned off, the resonant circuit discharges, generating an alternating magnetic field, which cuts the cookware and heats it.

[0003] However, during IGBT operation, it has been discovered that if the supply voltage is too high, the IGBT may experience hard turn-on. Hard turn-on occurs when the IGBT begins conducting before the collector voltage drops to 0 volts. When this occurs, the collector voltage is too high, potentially causing significant conduction losses in the IGBT, meaning the IGBT's on-current is too high. If this condition persists for a long time, it can cause the IGBT to heat up and potentially damage it.

[0004] In the prior art, when the IGBT is hard-turned on, the hard-turn-on voltage of the IGBT is reduced by adjusting the on-time of the IGBT to protect the IGBT from damage.

[0005] However, the following technical problems still exist in the existing technology: 1) Adjusting the on-time of the IGBT will cause a significant change in the heating power of the circuit in which the IGBT is located, thus affecting the performance. 2) It can only reduce the hard turn-on voltage of the IGBT to a certain extent, but cannot prevent the occurrence of hard turn-on phenomenon. Summary of the Invention

[0006] In order to at least partially solve the above technical problems, according to one aspect of the present invention, there is provided an insulated gate bipolar transistor control circuit, comprising: a resonant circuit, an insulated gate bipolar transistor, a sampling circuit, a master control circuit and a drive circuit, wherein the first end of the resonant circuit is used to be connected to the mains, the collector of the insulated gate bipolar transistor is connected to the second end of the resonant circuit, the emitter of the insulated gate bipolar transistor is used to be grounded, the master control circuit is connected to the gate of the insulated gate bipolar transistor via the drive circuit, the sampling circuit is connected between the master control circuit and the insulated gate bipolar transistor, and the insulated gate bipolar transistor control circuit further comprises a switching circuit; wherein the master control circuit is further connected to the resonant circuit via the switching circuit, and is used to control the switching circuit to be disconnected when the rate of change of the electrical parameter of the insulated gate bipolar transistor sampled by the sampling circuit exceeds a preset rate of change threshold, so as to adjust the capacitance value of the resonant circuit.

[0007] Therefore, when the capacitance value of the resonant circuit changes, the charging time of the capacitor in the resonant circuit also changes accordingly in each subsequent resonant cycle. This can eliminate the hard turn-on phenomenon of the IGBT. This prevents the IGBT from overheating, effectively reduces the probability of damage to the IGBT, and improves the operating reliability and lifespan of related products. Furthermore, this circuit does not require changing the on-time of the IGBT itself, avoiding significant changes in its heating power that could affect its performance.

[0008] Exemplarily, the sampling circuit is connected between the master control circuit and the gate of the insulated gate bipolar transistor, and is used to sample the voltage of the gate.

[0009] Since the hard turn-on phenomenon can cause a large voltage drop in the gate voltage within a certain period of time, sampling the gate voltage can more accurately and objectively reflect whether the insulated gate bipolar transistor has been hard turned on. The result is less susceptible to interference and has smaller errors.

[0010] Exemplarily, the sampling circuit includes: a first resistor, a second resistor and a third resistor; wherein the first resistor and the second resistor are connected in series between the gate of the insulated gate bipolar transistor and the ground, the third resistor is connected between the first node and the main control circuit, and the first node is the connection point of the first resistor and the second resistor.

[0011] The above circuit has a simple structure, uses fewer components and has a low cost. In addition, the three resistors all have a voltage divider function, which can effectively protect the master control circuit from damage.

[0012] Exemplarily, the sampling circuit is connected between the master control circuit and the collector of the insulated gate bipolar transistor, and is used to sample the current of the collector.

[0013] In the above technical solution, the hard turn-on of the IGBT is determined based on the collector current, which can ensure the accuracy of the operation of the IGBT control circuit.

[0014] Exemplarily, the master control circuit is specifically used to: calculate the difference between the electrical parameters sampled by the sampling circuit at every preset time interval; when the difference is greater than or equal to a preset change rate threshold, control the switching circuit to disconnect so that the capacitance value of the resonant circuit is reduced.

[0015] The above technical solution is simple in logic, can be implemented at a relatively low cost, and has high reliability.

[0016] Exemplarily, the master control circuit is further used to determine whether the electrical parameter currently sampled by the sampling circuit is less than or equal to a preset parameter threshold, wherein the calculation of the difference between the electrical parameters sampled at the next preset time interval is performed only when the electrical parameter currently sampled by the sampling circuit is less than or equal to the preset parameter threshold.

[0017] Therefore, the hard-on judgment of the next timing cycle can be directly executed when no voltage drop occurs, avoiding unnecessary calculation of the difference of electrical parameters, reducing calculation overhead and improving system speed.

[0018] Exemplarily, the master control circuit is further configured to: control the drive circuit to drive the insulated gate bipolar transistor to be turned on or off, wherein the calculation of the difference is performed only when the insulated gate bipolar transistor is in the on state.

[0019] As a result, the workload of the master control circuit can be greatly reduced, the system power consumption can be reduced, and the system life can be extended.

[0020] Exemplarily, the switching circuit includes: an interconnected switching control circuit and a relay; the relay is connected to the resonant circuit for performing a closing or opening operation to adjust the capacitance value of the resonant circuit; the switching control circuit is also connected to the main control circuit for controlling the relay to close or open based on a switching control signal from the main control circuit.

[0021] The master control circuit can generate different switch control signals based on the changes in the parameters obtained by the sampling circuit to achieve automatic control of the relay without human intervention. This can effectively protect the insulated gate bipolar transistor from damage in a timely manner.

[0022] Exemplarily, the switch control circuit includes: a transistor, a fourth resistor and a fifth resistor; the emitter of the transistor is grounded, the fifth resistor is connected between the base of the transistor and the ground, the gate of the transistor is also connected to the main control circuit via the fourth resistor, and the collector of the transistor is connected to the relay.

[0023] Thus, the transistor can be used to control the on / off state of the relay. The switch circuit has a simple structure and low cost.

[0024] Exemplarily, the resonant circuit includes: a first capacitor, a second capacitor and a first inductor, the first end of the first capacitor, the first end of the first inductor and the first end of the second capacitor are connected together to form the first end of the resonant circuit; the second end of the first capacitor and the second end of the first inductor are connected together to form the second end of the resonant circuit; the first end of the switching circuit is connected to the second end of the second capacitor; and the second end of the switching circuit is connected to the second end of the resonant circuit.

[0025] The above-mentioned resonant circuit can be used to change the capacitance value of the resonant circuit, thereby adjusting the charging time of the capacitance of the resonant circuit in each subsequent resonant cycle. If it is determined that a hard turn-on of the insulated gate bipolar transistor has occurred, the switch circuit can be disconnected. As a result, the capacitance value of the resonant circuit becomes smaller and the charging time becomes shorter. When the charging time is shortened, the premature turn-on of the insulated gate bipolar transistor can be avoided, thereby eliminating the hard turn-on phenomenon of the insulated gate bipolar transistor. In addition, the circuit structure is simple, fewer components are required, and the volume of the insulated gate bipolar control transistor control circuit is reduced.

[0026] According to another aspect of the present invention, an electromagnetic heating circuit is provided, which includes the above-mentioned insulated gate bipolar transistor control circuit, and the insulated gate bipolar transistor control circuit is used for heating.

[0027] In the electromagnetic heating circuit, the hard-on phenomenon of the IGBT is eliminated, thereby preventing the IGBT from overheating, effectively reducing the probability of IGBT damage, and improving the reliability and life of the electromagnetic heating circuit.

[0028] Exemplarily, the master control circuit is also used to: when the rate of change of the electrical parameters of the insulated gate bipolar transistor sampled by the sampling circuit exceeds a preset rate of change threshold, increase the heating power regulation ratio of the insulated gate bipolar transistor according to the adjustment amplitude of the capacitance value of the resonant circuit.

[0029] Increasing the heating power regulation ratio of the insulated gate bipolar transistor can effectively eliminate the decrease in heating power of electromagnetic induction heating caused by solving its hard turn-on problem, thereby ensuring the heating effect of the electromagnetic heating circuit and improving the user experience.

[0030] According to yet another aspect of the present invention, a cooking appliance is provided, comprising the electromagnetic heating circuit as described above.

[0031] In the above cooking appliance, the hard-on phenomenon of the IGBT is eliminated, thereby preventing the IGBT from overheating, effectively reducing the probability of IGBT damage, and improving the working reliability and life of the cooking appliance.

[0032] According to another aspect of the present invention, a method for controlling an insulated gate bipolar transistor is also provided, wherein the method is used for the insulated gate bipolar transistor control circuit as described above, and the method includes: sampling electrical parameters of the insulated gate bipolar transistor; determining the rate of change of the sampled electrical parameters; and when the rate of change exceeds a preset rate of change threshold, controlling the switching circuit to disconnect to adjust the capacitance value of the resonant circuit.

[0033] Exemplarily, determining the change rate of the sampled electrical parameter includes: calculating a difference between the sampled electrical parameter at every preset time interval, and using the difference as the change rate.

[0034] Exemplarily, the method also includes: determining whether the currently sampled electrical parameter is less than or equal to a preset parameter threshold; wherein, calculating the difference between the sampled electrical parameters at the next preset time interval is only performed when the currently sampled electrical parameter is less than or equal to the preset parameter threshold.

[0035] Exemplarily, the method also includes: controlling the driving circuit to drive the insulated gate bipolar transistor to be turned on or off; calculating the difference of the sampled electrical parameters at each preset time interval includes: calculating the difference of the sampled electrical parameters at each preset time interval only when the insulated gate bipolar transistor is in the on state.

[0036] Exemplarily, sampling the electrical parameter of the insulated gate bipolar transistor includes: sampling the gate voltage or the collector current of the insulated gate bipolar transistor.

[0037] This summary introduces a series of simplified concepts that will be further described in the detailed description. This summary is not intended to limit the key features and essential features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0038] The advantages and features of the present invention are described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The following drawings of the present invention are hereby incorporated into the present invention for understanding the present invention. The drawings show embodiments of the present invention and their descriptions, and are used to explain the principles of the present invention. In the drawings,

[0040] Figure 1 FIG. 1 is a schematic diagram showing an insulated gate bipolar transistor control circuit 100 according to an embodiment of the present invention;

[0041] Figure 2A A schematic diagram showing changes in electrical parameter waveforms of various ports of an insulated gate bipolar transistor when there is no hard turn-on according to an embodiment of the present invention;

[0042] Figure 2B A schematic diagram showing changes in electrical parameter waveforms of various ports of an insulated gate bipolar transistor when hard-turning occurs according to an embodiment of the present invention is shown;

[0043] Figure 3 FIG2 shows a schematic diagram of an insulated gate bipolar transistor control circuit according to another embodiment of the present invention;

[0044] Figure 4 A schematic flow chart showing a method for controlling an insulated gate bipolar transistor according to an embodiment of the present invention; and

[0045] Figure 5 A schematic flow chart of an insulated gate bipolar transistor control method according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0046] In the following description, numerous details are provided to facilitate a thorough understanding of the present invention. However, those skilled in the art will appreciate that the following description relates only to preferred embodiments of the present invention, and that the present invention may be practiced without one or more of these details. Furthermore, certain technical features well known in the art have not been described to avoid confusion with the present invention.

[0047] According to one aspect of the present invention, an insulated gate bipolar transistor control circuit is provided. Figure 1 FIG. 1 is a schematic diagram of an insulated gate bipolar transistor control circuit 100 according to an embodiment of the present invention. Figure 1 As shown, the IGBT control circuit 100 includes a resonant circuit 110 , an IGBT 120 , a sampling circuit 130 , a master control circuit 140 and a drive circuit 150 .

[0048] In the insulated gate bipolar transistor control circuit 100, the first end of the resonant circuit 110 is used to connect to the mains power supply to power the entire circuit. Generally, the mains power supply is an alternating current with a voltage of 220 volts and a frequency of 50 hertz. Preferably, the resonant circuit 110 can be connected to the mains power supply via a noise reduction circuit. The noise reduction circuit can be used to filter out interference signals in the mains power supply, for example, to suppress electromagnetic compatibility (EMC) conducted interference, to prevent these interference signals from affecting the operation of subsequent circuits. Simultaneously, the noise reduction circuit can also be used to prevent subsequent circuits connected to it from interfering with the mains power supply. The collector of the insulated gate bipolar transistor 120 is connected to the second end of the resonant circuit 110. In other words, the first end of the resonant circuit 110 is the power input terminal, and the electrical signal output by the second end of the resonant circuit 110 can be input to the collector of the insulated gate bipolar transistor 120. It will be understood that the resonant circuit 110 may include an inductor and a capacitor. The resonant circuit 110 can be divided into series resonance and parallel resonance according to the different connection relationships between the inductor and the capacitor. The emitter of the IGBT 120 is grounded.

[0049] The master control circuit 140 is connected to the gate of the insulated gate bipolar transistor 120 via the drive circuit 150. Under the control of the master control circuit 140, the drive circuit 150 is configured to send a pulse signal to the insulated gate bipolar transistor 120, causing the insulated gate bipolar transistor 120 to turn on or off in response to the pulse signal. When the insulated gate bipolar transistor 120 is turned on, the resonant circuit 110 is charged; when the insulated gate bipolar transistor 120 is turned off, the resonant circuit 110 is discharged. Furthermore, the resonant circuit 110 can generate an alternating magnetic field, causing the temperature of a conductor within the alternating magnetic field to increase. The master control circuit 140 can be constructed using electronic components such as comparators, registers, and digital logic circuits, or implemented using a processor chip such as a single-chip microcomputer, microprocessor, programmable logic controller (PLC), digital signal processor (DSP), field programmable gate array (FPGA), programmable logic array (PLA), or application-specific integrated circuit (ASIC), and its peripheral circuits.

[0050] The sampling circuit 130 is connected between the master control circuit 140 and the insulated gate bipolar transistor 120. The sampling circuit 130 can be used to sample the electrical parameters of the insulated gate bipolar transistor 120 and send the sampled electrical parameters to the master control circuit 140. The electrical parameters are used to determine whether there is a hard turn-on of the insulated gate bipolar transistor 120. The electrical parameters may include the voltage value or current value of a specific port of the insulated gate bipolar transistor 120. Figure 1In the example, the sampling circuit 130 is connected to the gate of the IGBT 120, thereby collecting electrical parameters of the gate of the IGBT 120. It will be appreciated that this is merely an example, and the sampling circuit 130 may also be connected to other terminals of the IGBT 120, such as its collector.

[0051] The IGBT control circuit 100 also includes a switch circuit 160. The master control circuit 140 is further connected to the resonant circuit 110 via the switch circuit 160. When the rate of change of the electrical parameter of the IGBT 120 sampled by the sampling circuit 130 exceeds a preset rate-of-change threshold, the master control circuit 140 controls the switch circuit 160 to disconnect, thereby adjusting the capacitance of the resonant circuit 110. When the rate of change exceeds the preset rate-of-change threshold, it is determined that the IGBT 120 has been hard-turned on. Upon determining that the IGBT 120 has been hard-turned on, the master control circuit 140 controls the switch circuit 160 to disconnect, thereby adjusting the capacitance of the resonant circuit 110.

[0052] Therefore, when the capacitance value of the resonant circuit 110 changes, the charging time of the capacitor in the resonant circuit 110 in each subsequent resonant cycle also changes accordingly. This can eliminate the hard turn-on phenomenon of the insulated gate bipolar transistor 120. As a result, the temperature of the insulated gate bipolar transistor 120 is avoided from being too high, the probability of damage to the insulated gate bipolar transistor 120 is effectively reduced, and the operating reliability and lifespan of the related products are improved. In addition, the circuit does not require changing the conduction time of the insulated gate bipolar transistor itself, avoiding large changes in its heating power that affect the use effect.

[0053] Figure 2A FIG. 1 is a schematic diagram showing the waveform changes of electrical parameters of various ports of the insulated gate bipolar transistor 120 when there is no hard turn-on according to an embodiment of the present invention. Figure 2A In FIG. 1 , the EXP pin represents a pin of the master control circuit 140 for controlling the driving circuit 150 . Figure 2A FIG. 1 shows the gate voltage waveform, collector voltage waveform and collector current waveform of the insulated gate bipolar transistor 120 when the EXP pin output voltage waveform is a square wave. Figure 2A As shown, the falling edge of the collector voltage waveform of the IGBT 120 is synchronized with the rising edge of the gate voltage waveform, that is, the IGBT 120 is turned on when the collector voltage is equal to 0V or close to 0V, so no hard turn-on occurs.

[0054] Figure 2B FIG2 is a schematic diagram showing the waveform changes of electrical parameters of each port of the insulated gate bipolar transistor 120 when the insulated gate bipolar transistor 120 is hard-turned on according to an embodiment of the present invention. Figure 2BThe falling edge of the collector voltage waveform and the rising edge of the gate voltage waveform are not synchronized. This means that the IGBT 120 is turned on prematurely before the collector voltage drops to near 0V, resulting in a higher hard-turn-on voltage. Furthermore, according to the equation power P = U * I, the higher the hard-turn-on voltage U, the greater the power loss. Increased losses in the IGBT 120 can significantly increase its temperature. Prolonged operation in this condition can shorten the lifespan of the IGBT 120.

[0055] When the IGBT 120 is hard-turned on, the hard-turn-on voltage of its collector may be too high, for example, close to or exceeding 100 volts, which may cause the pulse current of the collector to increase sharply and instantaneously. After the pulse current increases, it may interfere with the driving waveform of the gate of the IGBT 120 through the coupling of the printed circuit board (PCB) wiring, causing the voltage of the driving waveform to drop a lot during the rising edge, for example, from 0 volts to 18 volts, that is, a voltage drop phenomenon occurs. On the contrary, when the IGBT 120 is not hard-turned on, the driving waveform of its gate will not experience a voltage drop during the rising period. Figure 2A As shown in FIG, in the absence of hard-on of the IGBT 120, during the rising edge T2 of the gate voltage waveform of the IGBT 120, the gate voltage gradually rises without voltage drop. In sharp contrast, Figure 2B In the case of hard turn-on of the IGBT 120 , during the time interval T1 of the rising edge T2 of the gate voltage waveform, the gate voltage has an obvious voltage drop, and a difference X1 is generated.

[0056] Based on the above phenomenon, according to one embodiment of the present invention, the sampling circuit 130 can be connected between the master control circuit 140 and the gate of the insulated gate bipolar transistor 120 to sample the gate voltage. For example, an electronic component or device with analog-to-digital conversion functionality can also be connected between the sampling circuit 130 and the master control circuit 140. The sampling circuit 130 can acquire an analog voltage signal from the gate of the insulated gate bipolar transistor 120 and then convert this continuously varying analog voltage signal into a discrete digital signal via the electronic component or device. Compared to analog signals, digital signals are easier to process and store. The master control circuit 140 can then convert the converted digital signal into a corresponding voltage value, thereby completing the sampling of the gate voltage. Alternatively, the analog-to-digital conversion function can also be implemented using a module within the master control circuit 140, which is not limited here.

[0057] Since the hard turn-on phenomenon can cause a large voltage drop in the gate voltage within a certain period of time, sampling the gate voltage can more accurately and objectively reflect whether the insulated gate bipolar transistor has been hard turned on. The result is less susceptible to interference and has smaller errors.

[0058] Figure 3 FIG. 2 shows a schematic diagram of an insulated gate bipolar transistor control circuit according to another embodiment of the present invention. Figure 3 As shown, the sampling circuit 130 includes a first resistor R15, a second resistor R16, and a third resistor R14. The first resistor R15 and the second resistor R16 are connected in series between the gate of the insulated gate bipolar transistor 120 and ground. For example, the first end of the first resistor R15 is connected to the gate of the insulated gate bipolar transistor 120, the second end of the first resistor R15 is connected to the first end of the second resistor R16, and the second end of the second resistor R16 is grounded. The third resistor R14 is connected between a first node and the master control circuit 140, where the first node is the connection point between the first resistor R15 and the second resistor R16. For example, the first end of the third resistor R14 is connected to the first node, and the second end of the third resistor R14 can be connected to the control module master control circuit 140. Specifically, the gate voltage of the insulated gate bipolar transistor 120 is divided by the first resistor R15 and the second resistor R16, and then current-limited by the third resistor R14 before being input to the master control circuit 140 to obtain the gate voltage value. In this embodiment, the resistance values of the three resistors can be set according to specific needs and are not specifically limited thereto.

[0059] The above circuit has a simple structure, uses fewer components, and has a low cost. In addition, the three resistors all have a voltage divider function, which can effectively protect the master control circuit 140 from damage.

[0060] Reference again Figure 2A and Figure 2B .like Figure 2A As shown in FIG, in the absence of hard-on of the IGBT 120, during the rising edge T2 of the gate voltage waveform of the IGBT 120, the collector current has only a small fluctuation. Figure 2B In the case of hard turn-on of the IGBT 120 , the collector current decreases significantly during the time interval T1 during the rising edge T2 of the gate voltage waveform.

[0061] Based on the above phenomenon, according to another embodiment of the present invention, sampling circuit 130 can be connected between master control circuit 140 and the collector of insulated gate bipolar transistor 120 to sample the collector current. Similar to the method for sampling gate voltage described above, collector current can also be sampled using analog-to-digital conversion technology. Furthermore, in this embodiment, sampling circuit 130 can also be implemented using the above circuit structure. For example, sampling circuit 130 can also include a first resistor, a second resistor, and a third resistor. For the sake of brevity, these are not further described here.

[0062] In the above technical solution, the hard turn-on of the IGBT 120 is determined based on the collector current, which can ensure the accuracy of the operation of the IGBT control circuit.

[0063] Reference again Figure 3 ,like Figure 3 As shown, the resonant circuit 110 may include a first capacitor C1, a second capacitor C2, and a first inductor L1. The first end of the first capacitor C1, the first end of the first inductor L1, and the first end of the second capacitor C2 are connected together to form a first end of the resonant circuit 110. The second end of the first capacitor C1 and the second end of the first inductor L1 are connected together to form a second end of the resonant circuit 110. The first end of the switch circuit 160 is connected to the second end of the second capacitor C2. The second end of the switch circuit 160 is connected to the second end of the resonant circuit 110. It can be understood that Figure 3 The resonant circuit 110 shown is a parallel resonant circuit, so the on-off status of the switch circuit 160 can affect whether the second capacitor C2 in the resonant circuit 110 is connected to the resonant circuit 110 , thereby adjusting the capacitance value of the resonant circuit 110 .

[0064] The above-mentioned resonant circuit 110 can be used to change the capacitance value of the resonant circuit 110, thereby adjusting the charging time of the capacitance of the resonant circuit 110 in each subsequent resonant cycle. If it is determined that a hard turn-on of the insulated gate bipolar transistor 120 has occurred, the switch circuit 160 can be disconnected. As a result, the capacitance value of the resonant circuit 110 becomes smaller and the charging time becomes shorter. When the charging time is shortened, the premature turn-on of the insulated gate bipolar transistor 120 can be avoided, thereby eliminating the hard turn-on phenomenon of the insulated gate bipolar transistor 120. In addition, the circuit structure is simple, fewer components are required, and the volume of the insulated gate bipolar control transistor control circuit 100 is reduced.

[0065] like Figure 3As shown, switching circuit 160 may include a switch control circuit 161 and a relay RY1 interconnected with each other. Relay RY1 is connected to resonant circuit 110 and is configured to close or open the relay to adjust the capacitance of the resonant circuit. Switch control circuit 161 is also connected to master control circuit 140 and controls relay RY1 to close or open based on a switch control signal from master control circuit 140.

[0066] In this embodiment, the master control circuit 140 can detect whether the IGBT 120 has experienced a hard turn-on based on the rate of change of the electrical parameters of the IGBT 120 sampled by the sampling circuit 130. The master control circuit 140 can also generate different switch control signals based on the detection result. For example, upon detecting a hard turn-on of the IGBT 120, the master control circuit 140 can generate a switch control signal to open relay RY1 in the switch circuit 160, or to close relay RY1 in the switch circuit 160. Relay RY1 is connected to the resonant circuit 110, and the closed or open state of relay RY1 may affect the capacitance connected to the resonant circuit 110. For example, when relay RY1 is closed, the capacitance of the resonant circuit 110 increases. Conversely, when relay RY1 is open, the capacitance of the resonant circuit 110 decreases.

[0067] The master control circuit 140 can generate different switch control signals based on the changes in the parameters obtained by the sampling circuit 130 to achieve automatic control of the relay RY1 without manual intervention, thereby timely and effectively protecting the insulated gate bipolar transistor 120 from damage.

[0068] Reference again Figure 3 The switch control circuit 161 may include a transistor Q1, a fourth resistor R1, and a fifth resistor R2. The emitter of the transistor Q1 is grounded. The fifth resistor R2 is connected between the base of the transistor Q1 and ground. The base of the transistor Q1 is also connected to the master control circuit 140 via the fourth resistor R1. The collector of the transistor Q1 is connected to the relay RY1.

[0069] The fourth resistor R1 in the switch control circuit 161 can be connected to the master control circuit 140. When the master control circuit 140 detects a hard turn-on of the insulated gate bipolar transistor 120, it can output a low-level signal. This low-level signal controls the drive circuit 150 to turn off transistor Q1, de-energizing the coil of relay RY1 and disconnecting the two contacts of relay RY1. When relay RY1 is disconnected, the second end of capacitor C2 in the resonant circuit 110 is disconnected from the second end of the resonant circuit 110, thereby reducing the capacitance of the resonant circuit 110. For example, the resonant circuit 110 includes an inductor L1 and a capacitor C1. At this point, the capacitance of the resonant circuit 110 is equal to the capacitance of C1, e.g., 0.24 microfarads. Conversely, when the master control circuit 140 does not detect a hard turn-on of the insulated gate bipolar transistor 120, it can output a high-level signal. This high-level signal controls the drive circuit 150 to turn on transistor Q1, energizing the coil of relay RY1. According to the principle of electromagnetic induction, the two contacts of relay RY1 are attracted and relay RY1 is closed. When relay RY1 is closed, capacitor C2 in resonant circuit 110 is connected in parallel to resonant circuit 110. At this time, resonant circuit 110 includes inductor L1, capacitor C1 and capacitor C2. The capacitance value of resonant circuit 110 is equal to the capacitance value of capacitor C1 and capacitor C2 in parallel. For example, C1 = 0.24 microfarads, C2 = 0.06 microfarads, then the capacitance value C2 in parallel is equal to the capacitance value of capacitor C1 and capacitor C2 in parallel. 并 = C1 + C2 = 0.24 + 0.06 = 0.3 μF. This increases the capacitance of the resonant circuit 110.

[0070] Thus, the transistor Q1 can be used to control the on / off state of the relay RY1. The switch circuit 160 has a simple structure and low cost.

[0071] Reference again Figure 3 , the driving circuit 150 may include 3 transistors represented by Q2, Q3 and Q4 respectively, 7 resistors represented by R7, R8, ..., R12 and R13 and 1 capacitor C6, etc. The collector of the transistor Q3 is connected to the DC power supply via the resistor R13. For example, if the master control circuit 140 outputs a high level, the transistors Q2 and Q4 are turned on, and the transistor Q3 is turned off, then the gate of the insulated gate bipolar transistor 120 is a low level. As a result, the gate of the insulated gate bipolar transistor 120 loses the driving voltage, so that the insulated gate bipolar transistor 120 is in the off state. Conversely, when the master control circuit 140 outputs a low level, the transistors Q2 and Q4 are turned off, and the transistor Q3 is turned on. After that, the voltage of the DC power supply, for example Figure 3The 18V voltage shown can reach the gate of the IGBT 120 via the resistor R13, transistor Q3, and resistor R8. The gate of the IGBT 120 is then at a high level, reaching the driving voltage of the IGBT 120, turning on the IGBT 120. While the IGBT 120 is in the on state, its electrical parameters can be sampled.

[0072] like Figure 3 As shown, a Zener diode DW1 can be connected between the gate and emitter of the IGBT 120. This not only ensures that the voltage input from the drive circuit 150 to the IGBT 120 will not be divided by utilizing the unidirectional conductivity of the diode, but also keeps the voltage across the Zener diode DW1 essentially unchanged once it breaks down, thereby effectively protecting the IGBT 120 from damage.

[0073] As described above, the master control circuit 140 can be implemented using the control module U1. The control module U1 can be implemented using a chip. Figure 3 As shown, the control module U1 may be provided with the aforementioned EXP pin, which is connected to the drive circuit 150 and is used to output a drive signal to control the drive circuit 150 to drive the insulated gate bipolar transistor 120 to be turned on or off. The control module U1 may also be provided with an AD0 pin. The AD0 pin is connected to the sampling circuit 130 and is used to receive a sampling signal from the sampling circuit 130. The sampling signal includes information about the electrical parameters of the insulated gate bipolar transistor 120. The control module U1 may also be provided with an I / O pin. The I / O pin is connected to the switching circuit 160 and is used to output the aforementioned switch control signal to the switching circuit 160. It can be understood that the control module U1 may also be provided with a power supply pin VDD and a ground pin (not shown), etc., and those skilled in the art will understand their functions. For the sake of brevity, they will not be described here.

[0074] Alternatively, as Figure 3As shown, the IGBT control circuit 100 may also include a synchronization circuit and a rectifier and filter circuit. One end of the rectifier and filter circuit is connected to the mains power supply, and the other end is connected to one end of the synchronization circuit. The other end of the synchronization circuit is respectively connected to the collector and emitter of the IGBT 120. The synchronization circuit includes resistors R3, R4, R5, and R6. During normal operation, the voltage at the collector of the IGBT 120 is divided by resistors R5 and R6 and input to the master control circuit 140. The voltage after rectification and filtering by the rectifier and filter circuit is divided by resistors R3 and R4 and input to the master control circuit 140. It is understood that these two voltages can be input to different ports of the master control circuit 140. Taking the aforementioned master control circuit 140 implemented as a control module U1 as an example, the control module U1 may include two different ports VA and VB for receiving these two voltages. The comparator of the master control circuit 140 compares these input voltages to obtain oscillation information of the resonant circuit 110. If the divided voltage of the rectifier and filter circuit is lower than the divided voltage of the collector of the insulated gate bipolar transistor 120, it can be buffered by capacitor C4. When the comparator inversion condition is reached, the control module U1 can start the next pulse, that is, input a drive signal to the drive circuit 150 through the EXP pin to control the drive circuit 150 accordingly. This continuous cycle can achieve continuous oscillation.

[0075] For example, the master control circuit 140 is specifically configured to calculate the difference between the electrical parameters sampled by the sampling circuit 130 at predetermined time intervals. Furthermore, when the difference is greater than or equal to a predetermined rate-of-change threshold, the switch circuit 160 is controlled to be disconnected, thereby reducing the capacitance of the resonant circuit 110. The following describes the specific operation of the master control circuit 140 using the example of the sampling circuit 130 sampling the gate voltage of the insulated gate bipolar transistor 120. With reference to this description, those skilled in the art will appreciate that the operation of the master control circuit 140 when the sampling circuit 130 samples other electrical parameters of the insulated gate bipolar transistor 120 is not further described for the sake of brevity.

[0076] For example, the master control circuit 140 may include registers, timers, comparators, etc. The master control circuit 140 may first be initialized, for example, by clearing the values in the registers and timers to zero. Thereafter, the master control circuit 140 may be configured to perform a reset operation during the rising edge of the voltage on the gate of the insulated gate bipolar transistor 120, for example, Figure 2ADuring the illustrated time period T2, the difference in gate voltage change is calculated at preset time intervals. This difference can represent the speed of the voltage drop. The preset time interval can be set as needed, for example, to any value between 0.2 microseconds and 4 microseconds. There may be multiple preset time intervals within the T2 time period. The master control circuit 140 can use a timer therein for timing. When the timer starts timing, the sampled gate voltage value is stored in register V1. When the timer reaches the preset time interval, the sampled gate voltage value is stored in register V2. After the sampled gate voltage value is stored in register V2, a comparator in the master control circuit 140 compares the values stored in register V1 with those in register V2. For ease of description, the values stored in registers V1 and V2 are referred to as V1 and V2, respectively. For example, if V2 ≥ V1, it can be considered that no voltage drop occurred during the corresponding time interval, meaning that the insulated gate bipolar transistor 120 did not undergo a hard turn-on. If V2 < V1, V2 can be subtracted from V1 to obtain the gate voltage drop value X1 = V1 - V2, i.e., the difference in gate voltage change. The resulting value is stored in register X1. A determination is then made as to whether X1 is greater than or equal to a preset rate-of-change threshold Y1. If so, it can be assumed that the gate voltage of the insulated gate bipolar transistor 120 has experienced a significant voltage drop within the time interval, i.e., a hard turn-on has occurred. Y1 can be set as needed, preferably to any value between 2 and 15 volts. If the sampling circuit 130 samples the collector current of the insulated gate bipolar transistor 120, Y1 can be set to any reasonable value, such as between 20 and 70 amps. Similar to the aforementioned multiple values, Y1 can be stored in register Y1. After detecting a hard turn-on, the master control circuit 140 can control the switch circuit 160 to disconnect, thereby reducing the capacitance of the resonant circuit 110. At this point, the values of registers V1, V2, and X1 can all be cleared. If no hard turn-on is detected within this time interval, the current value of register V2 can be assigned to register V1, and the value of register V2 can be cleared to 0. The timer can then start the next round of timing, repeating the hard turn-on detection and control process until the circuit stops working.

[0077] The above technical solution is simple in logic, can be implemented at a relatively low cost, and has high reliability.

[0078] Exemplarily, the master control circuit 140 is further configured to determine whether the electrical parameter currently sampled by the sampling circuit 130 is less than or equal to a preset parameter threshold. Calculating the difference in the electrical parameter for the next preset time interval is performed only when the currently sampled electrical parameter is less than or equal to the preset parameter threshold.

[0079] As described above, the electrical parameter currently sampled by the sampling circuit 130, taking the sampling gate voltage as an example, is the value stored in register V2. If, as described above, the comparison shows that V2 ≥ V1, it means that the gate voltage is still in the rising stage. Next, it can be determined whether the value stored in register V2 is less than or equal to the preset parameter threshold. If not, it can be determined that the insulated gate bipolar transistor 120 is not hard-turned on, and the timer can perform the next round of timing operation. If so, the value in register V2 is assigned to register V1 to overwrite its previously stored value, and register V2 and the timer are initialized. After that, the timer can start the next timing operation for the preset time interval. Among them, the preset parameter threshold can be set based on the driving voltage of the gate of the insulated gate bipolar transistor 120, for example, it can be set to 18 volts.

[0080] Therefore, the hard-on judgment of the next timing cycle can be directly executed when no voltage drop occurs, avoiding unnecessary calculation of the difference of electrical parameters, reducing calculation overhead and improving system speed.

[0081] For example, the master control circuit 140 can be used to control the drive circuit 150 to drive the insulated gate bipolar transistor 120 to be turned on or off. The aforementioned calculation of the difference in electrical parameters sampled by the sampling circuit 130 is performed only when the insulated gate bipolar transistor 120 is in the on state. It can be understood that the hard turn-on of the insulated gate bipolar transistor 120 only occurs when it is in the on state. The master control circuit 140 drives the insulated gate bipolar transistor 120 to be in the on or off state by controlling the drive circuit 150. Therefore, the master control circuit can detect whether the insulated gate bipolar transistor 120 is hard-turned on when it controls the drive circuit 150 to drive the insulated gate bipolar transistor 120 to be turned on. This can greatly reduce the workload of the master control circuit 140, reduce system power consumption, and extend system life.

[0082] According to another aspect of the present invention, an electromagnetic heating circuit is provided, which includes the above-mentioned insulated gate bipolar transistor control circuit 100, wherein the insulated gate bipolar transistor control circuit 100 is used for heating.

[0083] In the above electromagnetic heating circuit, the hard-on phenomenon of the IGBT 120 is eliminated, thereby avoiding the overheating of the IGBT 120, effectively reducing the probability of damage to the IGBT 120, and improving the reliability and life of the electromagnetic heating circuit.

[0084] Exemplarily, the master control circuit 140 is further configured to increase the heating power modulation ratio of the IGBT 120 when the change rate of the electrical parameter of the IGBT 120 sampled by the sampling circuit exceeds a preset change rate threshold.

[0085] As described above, when the rate of change of the electrical parameters of the IGBT 120 sampled by the sampling circuit 130 exceeds a preset rate-of-change threshold, the master control circuit 140 can detect that the IGBT 120 has hard-turned on. When the IGBT 120 is hard-turned on, as described above, the master control circuit 140 can control the switch circuit 160 to disconnect, thereby reducing the capacitance of the resonant circuit 110. As the capacitance of the resonant circuit 110 decreases, the heating power used to heat the IGBT 120 also decreases. Furthermore, the capacitance of the resonant circuit 110 and the heating power of the IGBT 120 are positively correlated; the greater the capacitance reduction, the greater the decrease in heating power. At this point, the heating power modulation ratio of the IGBT 120 can be increased based on the adjustment range of the resonant circuit capacitance. The heating power modulation ratio refers to the proportion of the IGBT 120 heating time within a heating cycle. The heating time can be adjusted by adjusting the duty cycle. For example, increasing the duty cycle can extend the heating time, while decreasing the duty cycle can shorten the heating time. Prolonging the heating time can appropriately increase the equivalent power of heating, thereby compensating for the decrease in heating power.

[0086] Increasing the heating power modulation ratio of the insulated gate bipolar transistor 120 can effectively eliminate the decrease in heating power of electromagnetic induction heating caused by solving its hard turn-on problem, thereby ensuring the heating effect of the electromagnetic heating circuit and improving the user experience.

[0087] According to yet another aspect of the present invention, a cooking appliance is provided, which may include the electromagnetic heating circuit described above.

[0088] In the example described above, capacitor C1 in resonant circuit 110 is 0.24 microfarads, and capacitor C2 is 0.06 microfarads. When capacitors C1 and C2 are connected in parallel, the capacitance of resonant circuit 110 is 0.3 microfarads. Assume that after the master control circuit 140 determines that the insulated gate bipolar transistor 120 has been hard-turned on, the hard-turn-on voltage, i.e., the collector voltage, of the insulated gate bipolar transistor 120 is 96 volts. When capacitor C2 is disconnected from resonant circuit 110, the capacitance of resonant circuit 110 becomes 0.24, and the capacitance drop value is 0.06 microfarads. In this example, the capacitance drop value of resonant circuit 110 refers to the capacitance value of capacitor C2. This is because after determining that the insulated gate bipolar transistor 120 has been hard-turned on, the master control circuit 140 controls the switch circuit 160 to disconnect, thereby disconnecting capacitor C2 from resonant circuit 110. The collector voltage becomes 16 volts, close to 0 volts. For example, consider an electromagnetic induction heating rice cooker with a rated power of 1300 watts. Assuming the rice cooker is currently in the water absorption phase of its cooking function, the heating power modulation ratio during this phase is 10:30. This means that within each 30-second power modulation cycle, heating occurs for 10 seconds and heating is stopped for 20 seconds. Based on the rated power, the equivalent power during the water absorption phase can be calculated as P1 = 1300*(10 / 30) = 433 watts. Table 1 shows various data measured for this rice cooker under a mains voltage of 242 volts. The test data in Table 1 show that when the capacitance of the resonant circuit 110 decreases from 0.3 microfarads to 0.24 microfarads, the measured heating power of the rice cooker decreases from 1271 watts to 1245 watts, a decrease of 26 watts. The hard-on voltage also decreases from 96 volts to 16 volts.

[0089] Table 1

[0090]

[0091] Table 2 shows the range of capacitance drop values and the corresponding equivalent power increase rate for resonant circuit 110. The master control circuit 140 can select a corresponding equivalent power increase rate range based on the capacitance adjustment amplitude (i.e., drop value) of resonant circuit 110 in Table 2. It then selects a specific equivalent power increase rate within this range based on the current cooking function and cooking stage. The heating power ratio for subsequent cooking stages is adjusted based on the final selected equivalent power increase rate, and heating is performed at the adjusted heating power ratio. For example, the 26-watt drop caused by eliminating the hard-on operation is approximately 2% of the original operating power of 1271 watts. Therefore, during the subsequent cooking process, the equivalent power must increase by at least 2% to compensate for the reduced heating power. Table 2 also shows that when the capacitance drop value in resonant circuit 110 is less than 0.06 microfarads, the corresponding equivalent power increase rate ranges from 1% to 6%. A specific equivalent power increase rate can be selected within this range based on the current cooking function and cooking stage. Since the rice cooking function is currently in the water absorption phase, subsequent cooking steps include a rapid heating phase, a boiling maintenance phase, and a rice simmering phase. During the rapid heating phase, full power heating is used for the majority of the time. Full-power heating means the heating power modulation ratio cannot be adjusted. Therefore, the equivalent power increase rate is set to a maximum of 6% to mitigate the adverse effects of a slight decrease in electromagnetic induction heating power during full-power heating on the cooking effect. Assuming the current cooking phase is the boiling maintenance phase or the rice simmering phase, the equivalent power increase rate can be taken as the theoretical value of 2% calculated above.

[0092] Table 2

[0093] Capacitance drop of the resonant circuit (uF) Equivalent power increase rate in subsequent cooking stages ≤0.06uF 1％～6％ 0.061uF~0.1uF 2％～9％ >0.1uF 4％～15％

[0094] Taking the maximum equivalent power increase rate as an example, calculation shows that the adjusted equivalent power P2 during the water absorption phase is P1*(1+6%)=433*1.06=458 watts. Assuming that the equivalent power P2 during the water absorption phase is adjusted by adjusting the power modulation cycle, then according to P2=1300*(10 / adjusted power modulation cycle), substituting 458 watts = 1300*(10 / adjusted power modulation cycle), we can solve for the adjusted power modulation cycle to be approximately 28 seconds. This means that the adjusted heating power modulation ratio during the water absorption phase is 10:28, meaning that within each 28-second power modulation cycle, heating occurs for 10 seconds and heating is stopped for 18 seconds.

[0095] In the above cooking appliance, the hard-on phenomenon of the IGBT 120 is eliminated, thereby preventing the IGBT 120 from overheating, effectively reducing the probability of damage to the IGBT 120, and improving the reliability and life of the cooking appliance.

[0096] According to yet another aspect of the present invention, a method for controlling an insulated gate bipolar transistor is provided. Figure 4 FIG. 4 is a schematic flow chart of an insulated gate bipolar transistor control method 400 according to an embodiment of the present invention. Figure 4 As shown, the method 400 includes:

[0097] Step S410 , sampling electrical parameters of the insulated gate bipolar transistor.

[0098] Step S420: determining the rate of change of the sampled electrical parameter.

[0099] In step S430 , when the change rate exceeds a preset change rate threshold, the switch circuit is controlled to be disconnected to adjust the capacitance value of the resonant circuit.

[0100] Exemplarily, determining the change rate of the sampled electrical parameter in step S420 includes calculating a difference between the sampled electrical parameter at every preset time interval, and using the difference as the change rate.

[0101] Exemplarily, method 400 may further include determining whether the currently sampled electrical parameter is less than or equal to a preset parameter threshold, wherein calculating the difference between the sampled electrical parameters at the next preset time interval is performed only when the currently sampled electrical parameter is less than or equal to the preset parameter threshold.

[0102] Exemplarily, method 400 may further include controlling a driving circuit to drive the insulated gate bipolar transistor to be turned on or off. Calculating the difference in the sampled electrical parameter at each preset time interval includes calculating the difference in the sampled electrical parameter at each preset time interval only when the insulated gate bipolar transistor is in an on state.

[0103] Exemplarily, sampling the electrical parameter of the insulated gate bipolar transistor includes sampling a gate voltage or a collector current of the insulated gate bipolar transistor.

[0104] Those skilled in the art can understand the specific implementation steps and corresponding beneficial effects of the insulated gate bipolar transistor control method by reading the above description of the insulated gate bipolar transistor control circuit. For the sake of brevity, they will not be described in detail here.

[0105] Figure 5 FIG. 1 shows a schematic flow chart of an insulated gate bipolar transistor control method according to another embodiment of the present invention. Figure 5As shown, the control module is first initialized. The sampling circuit then samples the gate voltage of the insulated gate bipolar transistor (IGBT) to obtain its voltage value. If the EXP pin of the control module outputs a high level, the IGBT is in the off state, and the gate voltage is sampled again. When the EXP pin of the control module outputs a low level, the IGBT is in the on state. The obtained voltage value is stored in register V1, and a timer starts counting. After the timer reaches the preset time interval T, the current sampled voltage value is stored in register V2. V2 is compared with V1. When V2 < V1, V2 is subtracted from V1 to obtain the voltage drop value X1. The voltage drop value X1 is then compared with the preset conversion rate threshold Y1. When X1 is greater than or equal to Y1, it is determined that the IGBT has hard-turned on, and all data stored in the control module, such as V1 and V2, are cleared. At this point, the control module can send a switch control signal through the I / O pin to control the switch circuit to disconnect, thereby reducing the capacitance of the resonant circuit. If X1 is less than Y1, it can be determined that the IGBT has not experienced a hard turn-on. The control module controls the switch circuit to close, initiating a new round of hard turn-on detection. If V2 ≥ V1, it first determines whether V2 is greater than or equal to a preset parameter threshold, such as 18 volts. If V2 ≥ 18 volts, it can also be determined that the IGBT has not experienced a hard turn-on. The control module controls the switch circuit to close, initiating a new round of hard turn-on detection. Otherwise, the control module assigns the value of register V2 to register V1. Register V2 is cleared, and the timer begins the next round of timing.

[0106] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, parts, components and / or combinations thereof.

[0107] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0108] The present invention has been described through the above-described embodiments, but it should be understood that the above-described embodiments are for illustrative and illustrative purposes only and are not intended to limit the present invention to the scope of the described embodiments. Furthermore, those skilled in the art will appreciate that the present invention is not limited to the above-described embodiments and that various variations and modifications may be made based on the teachings of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An insulated gate bipolar transistor control circuit, comprising: A resonant circuit, an insulated gate bipolar transistor, a sampling circuit, a master control circuit, and a drive circuit, wherein the first end of the resonant circuit is used to be connected to the mains, the collector of the insulated gate bipolar transistor is connected to the second end of the resonant circuit, the emitter of the insulated gate bipolar transistor is used to be grounded, the master control circuit is connected to the gate of the insulated gate bipolar transistor via the drive circuit, the sampling circuit is connected between the master control circuit and the insulated gate bipolar transistor, and the insulated gate bipolar transistor control circuit also includes a switching circuit; wherein, The master control circuit is also connected to the resonant circuit via the switching circuit, and is configured to control the switching circuit to disconnect when the rate of change of the electrical parameter of the insulated gate bipolar transistor sampled by the sampling circuit exceeds a preset rate of change threshold, so as to adjust the capacitance value of the resonant circuit, wherein the electrical parameter is the gate voltage or the collector current.

2. The insulated gate bipolar transistor control circuit according to claim 1, wherein: The sampling circuit is connected between the master control circuit and the gate of the insulated gate bipolar transistor, and is used for sampling the voltage of the gate.

3. The insulated gate bipolar transistor control circuit according to claim 2, wherein: The sampling circuit includes: a first resistor, a second resistor and a third resistor; wherein, The first resistor and the second resistor are connected in series between the gate of the insulated gate bipolar transistor and the ground. The third resistor is connected between a first node and the master control circuit. The first node is a connection point between the first resistor and the second resistor.

4. The insulated gate bipolar transistor control circuit according to claim 1, wherein: The sampling circuit is connected between the master control circuit and the collector of the insulated gate bipolar transistor, and is used for sampling the current of the collector.

5. The insulated gate bipolar transistor control circuit according to any one of claims 1 to 4, wherein: The master control circuit is specifically used for: Calculating the difference between the electrical parameters sampled by the sampling circuit at every preset time interval; When the difference is greater than or equal to the preset change rate threshold, the switch circuit is controlled to be disconnected, so that the capacitance value of the resonant circuit is reduced.

6. The insulated gate bipolar transistor control circuit according to claim 5, wherein: The master control circuit is further configured to determine whether the electrical parameter currently sampled by the sampling circuit is less than or equal to a preset parameter threshold, wherein the calculation of the difference between the electrical parameters sampled at the next preset time interval is performed only when the electrical parameter currently sampled by the sampling circuit is less than or equal to the preset parameter threshold.

7. The insulated gate bipolar transistor control circuit according to claim 5, wherein: The master control circuit is further configured to control the drive circuit to drive the insulated gate bipolar transistor to be turned on or off, wherein the calculation of the difference between the electrical parameters sampled by the sampling circuit at each preset time interval is performed only when the insulated gate bipolar transistor is in the on state.

8. The insulated gate bipolar transistor control circuit according to any one of claims 1 to 4, wherein: The switch circuit includes: a switch control circuit and a relay interconnected; The relay is connected to the resonant circuit and is used to perform a closing or opening operation to adjust the capacitance value of the resonant circuit; The switch control circuit is also connected to the master control circuit and is used to control the relay to be closed or opened based on a switch control signal from the master control circuit.

9. The insulated gate bipolar transistor control circuit according to claim 8, wherein: The switch control circuit includes: a transistor, a fourth resistor and a fifth resistor; The emitter of the transistor is grounded, the fifth resistor is connected between the base of the transistor and the ground, the base of the transistor is also connected to the main control circuit via the fourth resistor, and the collector of the transistor is connected to the relay.

10. The insulated gate bipolar transistor control circuit according to any one of claims 1 to 4, wherein: The resonant circuit includes: a first capacitor, a second capacitor and a first inductor, The first end of the first capacitor, the first end of the first inductor and the first end of the second capacitor are connected together to form a first end of the resonant circuit; The second end of the first capacitor and the second end of the first inductor are connected together to form a second end of the resonant circuit; The first end of the switch circuit is connected to the second end of the second capacitor; The second end of the switch circuit is connected to the second end of the resonant circuit.

11. An electromagnetic heating circuit, wherein: The invention comprises the insulated gate bipolar transistor control circuit according to any one of claims 1 to 10, wherein the insulated gate bipolar transistor control circuit is used for heating.

12. The electromagnetic heating circuit according to claim 11, wherein: The master control circuit is further configured to increase the heating power regulation ratio of the insulated gate bipolar transistor according to the adjustment amplitude of the capacitance value of the resonant circuit when the change rate of the electrical parameter of the insulated gate bipolar transistor sampled by the sampling circuit exceeds a preset change rate threshold.

13. A cooking appliance, wherein: Comprising the electromagnetic heating circuit according to claim 11 or 12.

14. A method for controlling an insulated gate bipolar transistor, wherein: The method is used for the insulated gate bipolar transistor control circuit according to any one of claims 1 to 10, and the method comprises: sampling electrical parameters of the insulated gate bipolar transistor; determining a rate of change of the sampled electrical parameter; and When the change rate exceeds a preset change rate threshold, the switch circuit is controlled to be disconnected to adjust the capacitance value of the resonant circuit.

15. The method of claim 14, wherein: Determining the rate of change of the sampled electrical parameter includes: The difference between the sampled electrical parameters at every preset time interval is calculated to use the difference as the change rate.

16. The method of claim 15, wherein: The method further comprises: Determine whether the currently sampled electrical parameter is less than or equal to a preset parameter threshold; The calculation of the difference between the electrical parameters sampled at the next preset time interval is performed only when the currently sampled electrical parameter is less than or equal to the preset parameter threshold.

17. The method of claim 15, wherein: The method further comprises: Controlling the driving circuit to drive the insulated gate bipolar transistor to be turned on or off; The calculating of the difference of the sampled electrical parameters at every preset time interval includes: Only when the insulated gate bipolar transistor is in the on state, the difference of the sampled electrical parameter at every preset time interval is calculated.

18. The method according to any one of claims 14 to 17, wherein: The sampling of electrical parameters of the insulated gate bipolar transistor includes: The gate voltage or collector current of the insulated gate bipolar transistor is sampled.

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