Electromagnetic heating IGBT (Insulated Gate Bipolar Translator) driving circuit and electromagnetic cooking utensil

Abstract

The invention provides an electromagnetic heating IGBT (Insulated Gate Bipolar Translator) driving circuit and an electromagnetic cooking utensil, the IGBT driving circuit comprises a driving signal input end, a push-pull module, a driving power supply, a first driving module, a second driving module and a voltage regulation module, and the output end of the voltage regulation module is connected with the input end of the push-pull module; the input ends of the first driving module and the second driving module are connected with a driving signal input end to obtain a driving signal; the first driving module controls the enabling of the voltage adjusting module according to the driving signal so as to adjust the voltage of the input end of the push-pull module; and the second driving module closes the voltage regulation module according to the driving signal so as to connect the driving power supply to the input end of the push-pull module. The electromagnetic cooking utensil comprises a main control circuit provided with the IGBT circuit. According to the invention, the conduction speed of the IGBT can be reduced, and the explosion risk and the switching-on noise can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic heating, in particular to an IGBT driving circuit for electromagnetic heating and an electromagnetic cooking appliance. Background Art

[0002] At present, most of the common induction cookers on the market use an electromagnetic resonant circuit composed of IGBT (Insulated Gate Bipolar Transistor) to realize its electromagnetic heating function, and most of the electromagnetic resonant circuits work in parallel resonance. However, during the operation of the induction cooker, it is often encountered in the scene that long-term low-power heating is required. In the process of maintaining long-term low-power heating by the electromagnetic resonant circuit composed of IGBT, the problem of IGBT voltage advance opening often occurs. The IGBT voltage advance opening will cause the IGBT to have too high a conduction voltage at the moment of conduction, which will cause its conduction current to be too high. Both high conduction current and high conduction voltage will increase the risk of explosion and working noise of the induction cooker, affecting the safety of the induction cooker and the user experience. Summary of the invention

[0003] In view of the problem that when the existing induction cooker performs electromagnetic heating through the electromagnetic resonant circuit composed of IGBT, the IGBT voltage is turned on in advance, the risk of explosion and the increased working noise exist, the purpose of the present invention is to provide an IGBT driving circuit and an electromagnetic cooking appliance for electromagnetic heating, which can soft-start the IGBT with a lower voltage when driven by each driving signal, and then start the IGBT with a normal voltage after a certain period of time, thereby realizing the deceleration start of the IGBT and reducing the conduction speed of the IGBT, thereby avoiding the problem of the IGBT voltage being turned on in advance. At the moment of the IGBT being turned on, there will be no high conduction voltage and high conduction current, thereby reducing the risk of explosion and the turn-on noise, thereby ensuring the safety of the induction cooker and the user experience.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An IGBT driving circuit for electromagnetic heating, comprising:

[0006] A driving signal input terminal, used to receive a driving signal for driving the IGBT;

[0007] IGBT push-pull module, used to control the conduction state of IGBT;

[0008] A driving power supply, used to supply power to the IGBT driving circuit;

[0009] It also includes a first driving module, a second driving module, and a voltage regulating module.

[0010] The output ends of the voltage regulating modules are all connected to the input ends of the push-pull modules;

[0011] The input ends of the first driving module and the second driving module are connected to the driving signal input end to obtain the driving signal;

[0012] The first driving module controls the voltage regulating module to enable according to the driving signal to adjust the voltage at the input end of the push-pull module; the second driving module turns off the voltage regulating module according to the driving signal to connect the driving power supply to the input end of the push-pull module.

[0013] In this technical solution, the voltage at the input end of the push-pull module is controlled by the start-up time difference between the first drive module and the second drive module, thereby achieving the purpose of controlling the on-voltage of the IGBT, so that the IGBT can be driven with two drive voltages in succession. The push-pull module first pre-turns on the IGBT with the voltage adjusted by the voltage adjustment module, and then turns on the IGBT with the corresponding voltage of the drive power supply, effectively avoiding the occurrence of the IGBT advanced conduction phenomenon, and solving the problem of the risk of explosion and increased working noise caused by the high on-voltage and high on-current of the IGBT.

[0014] The present invention is further configured such that: the first driving module is started prior to the second driving module according to the driving signal.

[0015] Through this setting, each time the IGBT is turned on, the first drive module and the second drive module can be started successively according to the same drive signal, thereby achieving the purpose of regulating the on-state voltage of the IGBT. Without the need for software judgment and control, the regulation of the on-state voltage of the IGBT is achieved in a purely hardware manner, and the regulation effect is more stable and reliable.

[0016] The present invention is further configured such that: the first driving module includes an acceleration circuit connected between the first driving module input terminal and the driving signal input terminal, and the first driving module obtains the driving signal through the acceleration circuit in priority to the second driving module.

[0017] Through this configuration, the startup time difference between the first drive module and the second drive module is achieved through an acceleration circuit. After the drive signal is input, the first drive module can obtain the drive signal first through the acceleration circuit and then start, so that after the drive signal is input, the push-pull module can first turn on the IGBT with the voltage adjusted by the voltage adjustment module, thereby realizing low-voltage pre-conduction of the IGBT and ensuring the conduction safety of the IGBT.

[0018] The present invention is further configured as follows: the acceleration circuit includes an acceleration capacitor connected in parallel in the acceleration circuit, and the driving signal is input into the first driving module after being accelerated by the acceleration capacitor.

[0019] Through this configuration, the acceleration circuit specifically realizes the accelerated startup of the first driving module through the acceleration capacitor, and the speed and time of the accelerated startup of the first driving module can be adjusted by the acceleration capacitor, so that the startup time difference between the first driving module and the second driving module is adjustable. In addition to being able to accelerate the startup of the first driving module, the acceleration capacitor can also more quickly shut down the first driving module when the level of the driving signal is switched, thereby quickly shutting down the IGBT and increasing the timeliness of the IGBT control.

[0020] The present invention is further configured such that: the second driving module includes a delay circuit connected between the second driving module input terminal and the driving signal input terminal, and the second driving module obtains the driving signal later than the first driving module through the delay circuit.

[0021] Through this configuration, a start-up time difference between the first drive module and the second drive module is achieved through a delay circuit. After the drive signal is input, the second drive module can obtain the drive signal by delaying one step through the delay circuit, so that after the drive signal is input, the push-pull module can first turn on the IGBT with the voltage adjusted by the voltage adjustment module, thereby realizing low-voltage pre-conduction of the IGBT and ensuring the conduction safety of the IGBT.

[0022] The present invention is further configured as follows: the delay circuit is provided with at least one stage, each stage of the delay circuit includes a switch element and a current limiting element connected in series in the delay circuit, and the drive signal is input into the second drive module after being delayed by the current limiting element and the switch element connected in series.

[0023] Through this setting, the time for delayed start of the second driver module can be adjusted by setting the number of stages of the delay circuit, so that the start-up time difference between the first driver module and the second driver module is adjustable. Each level of delay circuit requires a certain time to be turned on, so the delay time can be adjusted by adjusting the number of stages of the delay circuit. The more stages of the delay circuit, the longer the delay time. And the on-time of the switch element in each level of delay circuit can be adjusted by the conduction current value. Under the premise of a circuit in which the current limiting element and the switch element are connected in series, the on-time of the switch element can be adjusted by setting the value of the current limiting element, and then the on-time of each level of delay circuit is adjusted. Therefore, in addition to adjusting the time for delayed start of the second driver module by setting the number of stages of the delay circuit, the time for delayed start of the second driver module can also be adjusted by adjusting the value of the current limiting element in the delay circuit.

[0024] The present invention is further configured to include: a digital clock module, which is arranged between the driving signal input terminal and the input terminals of the first driving module and the second driving module;

[0025] The first driving module and the second driving module control the voltage regulating module to enable or disable the voltage regulating module according to the driving signal passing through the digital clock module.

[0026] Through this setting, after receiving the driving signal, the digital clock module can input the driving signal to the first driving module and the second driving module according to the preset time, so as to control the first driving module and the second driving module to start one after another, and the digital clock module can adjust the time of inputting the driving signal to the first driving module and the second driving module according to the demand, so that the startup time difference between the first driving module and the second driving module can be adjusted.

[0027] The present invention is further configured as follows: the voltage regulating module includes a voltage dividing circuit,

[0028] The first driving module controls the voltage divider circuit to enable according to the driving signal, so as to adjust the voltage at the input end of the push-pull module to the voltage divided by the voltage divider circuit;

[0029] The second driving module turns off the voltage dividing circuit according to the driving signal to adjust the voltage at the input end of the push-pull module to the driving power supply voltage that has not been divided by the voltage dividing circuit.

[0030] Through this configuration, the voltage at the input end of the push-pull module can be adjusted through the voltage divider circuit, and the enabling and shutting down of the voltage divider circuit are completely controlled by the first drive module and the second drive module, without the need for software judgment and control, and the adjustment and switching of the IGBT conduction voltage is completely realized by hardware, and the adjustment effect is more stable and reliable. After the voltage is divided by the voltage divider circuit, it is ensured that the voltage at the input end of the push-pull module can pre-turn on the IGBT with a lower voltage, and then turn on the IGBT normally with the driving power supply voltage that has not been divided by the voltage divider circuit, avoiding the problem of the IGBT voltage being turned on ahead of time.

[0031] The present invention is further configured to include: a control signal input end of a voltage regulating module, the control signal input end receives an external control signal to shut down the voltage regulating module when the second driving module is started; and control the voltage regulating module to be enabled when the first driving module is started.

[0032] Through this configuration, the external control signal can be determined according to the startup conditions of the first drive module and the second drive module, so that the two different input voltages can be controlled by the external control signal. Similarly, the voltage regulation of the input end of the push-pull module can be achieved, so that the push-pull module can pre-turn on the IGBT with a lower voltage, and then turn on the IGBT normally with the driving power supply voltage, thereby achieving the purpose of avoiding the IGBT voltage from being turned on in advance.

[0033] An electromagnetic cooking appliance comprises a main control circuit for controlling the operation of the electromagnetic cooking appliance, the cooking appliance comprises a first power operating mode and a second power operating mode, the power of the second operating mode is greater than the power of the first operating mode, and the power of the first power operating mode is not greater than 600 watts, the main control circuit comprises the IGBT drive circuit in any one of the above embodiments, so that the first power operating mode and the second power operating mode are both continuous heating modes.

[0034] It should be noted that in any of the above technical solutions, the electromagnetic cooking appliance includes any one of an induction cooker, an electric rice cooker, an electric pressure cooker, and an electric hot pot.

[0035] In the description of the present invention, it should be noted that the "electromagnetic cooking appliance" mentioned in the present invention may include any cooking equipment that can cook food and to which the technical solution of the present invention can be applied, including but not limited to induction cookers, electric pressure cookers, electric rice cookers, and electric hot pots.

[0036] The beneficial effects of the present invention are:

[0037] 1. Only one driving signal is used to control the first driving module and the second driving module, so that there is a time difference in the startup of the two modules. The startup time difference between the first driving module and the second driving module is used to realize the soft start of the IGBT with a lower voltage when each driving signal is driven. After a certain period of time, the IGBT is started with a normal voltage, thereby realizing the deceleration start of the IGBT and reducing the conduction speed of the IGBT, thereby avoiding the problem of the IGBT voltage being turned on in advance. At the moment of the IGBT being turned on, there will be no high conduction voltage and high conduction current, reducing the risk of explosion and the turn-on noise, thereby ensuring the safety of the induction cooker and the user experience.

[0038] 2. No software judgment and control is required, and the IGBT on-voltage regulation is achieved through pure hardware, making the regulation effect more stable and reliable.

[0039] 3. The IGBT driving circuit is integrated into the main control circuit to improve its convenience of use and reduce its cost. The main control circuit uses the IGBT driving circuit in the present invention to enable the electromagnetic cooking appliance to achieve continuous heating and cooking regardless of whether it is in the second working mode with higher power or the first working mode with lower power. Especially in the first working mode with lower power, compared with the intermittent heating mode adopted in the prior art, the user experience is greatly optimized. At the same time, since the voltage and current at the moment of IGBT conduction are reduced, the service life of the electromagnetic cooking appliance is guaranteed.

[0040] 4. While using the acceleration circuit to accelerate the conduction of the first drive module, the acceleration circuit can also be used to accelerate the turn-off speed of the IGBT, thereby increasing the timeliness of the IGBT control. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural schematic diagram of an electromagnetic heating IGBT drive circuit of the present invention;

[0042] Figure 2 is a block diagram of an IGBT driving circuit according to Embodiment 1 of the present invention;

[0043] Figure 3 is a circuit diagram of an IGBT driving circuit according to Embodiment 1 of the present invention;

[0044] Figure 4 This is a schematic diagram comparing the change curves of a driving signal and an IGBT base voltage according to Embodiment 1 of the present invention;

[0045] Figure 5 is a block diagram of an IGBT driving circuit according to Embodiment 2 of the present invention;

[0046] Figure 6 is a current schematic diagram of an IGBT driving circuit according to Embodiment 2 of the present invention;

[0047] Figure 7 This is a schematic diagram comparing the change curves of a driving signal and an IGBT base voltage according to Embodiment 2 of the present invention;

[0048] Figure 8 is a block diagram of an IGBT driving circuit according to Embodiment 3 of the present invention;

[0049] Fig. 9 It is a block diagram of an IGBT driving circuit according to embodiment 4 of the present invention.

[0050] Among them: 1. drive signal input terminal, 2. push-pull module, 3. drive power supply, 4. first drive module, 41. acceleration circuit, 5. second drive module, 51. delay circuit, 6. voltage regulation module, 61. voltage divider circuit, 62. power supply unit, 7. digital clock module, 8. control signal input terminal, 9. IGBT. DETAILED DESCRIPTION

[0051] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0052] like Figure 1 As shown, an IGBT driving circuit for electromagnetic heating includes:

[0053] A drive signal input terminal 1, used to receive a drive signal for driving the IGBT9;

[0054] The push-pull module 2 of the IGBT is used to control the conduction state of the IGBT;

[0055] A driving power supply 3, used to supply power to the IGBT driving circuit;

[0056] It also includes a first driving module 4, a second driving module 5, and a voltage regulating module 6.

[0057] The output ends of the voltage regulating module are connected to the input ends of the push-pull module; the input ends of the first driving module and the second driving module are connected to the driving signal input end to obtain the driving signal;

[0058] The first driving module controls the voltage regulating module to enable according to the driving signal to adjust the voltage at the input end of the push-pull module; the second driving module turns off the voltage regulating module according to the driving signal to connect the driving power supply to the input end of the push-pull module.

[0059] When it is necessary to control the operation of the IGBT, the drive signal input terminal will simultaneously input the same drive signal to the first drive module and the second drive module. After receiving the drive signal, the first drive module can automatically control the voltage regulation module to enable, thereby adjusting the voltage at the input end of the push-pull module through the voltage regulation module. After receiving the drive signal, the second drive module can automatically turn off the voltage regulation module, and the drive power supply can be directly connected to the input end of the push-pull module. The first drive module and the second drive module cooperate with each other to adjust the voltage at the input end of the push-pull module through the same drive signal, thereby controlling the on-voltage of the IGBT. By controlling and adjusting the on-voltage of the IGBT, the problem of early turn-on of the IGBT voltage can be effectively avoided. At the moment of IGBT turn-on, high on-voltage and high on-current will no longer appear, reducing the risk of explosion and turn-on noise, and ensuring the safety of the induction cooker and the user experience.

[0060] Furthermore, the first driving module and the second driving module do not need software judgment and control to control the on and off of the voltage regulating module, but rely on pure hardware to achieve it, making the control and regulation effect of the on-voltage of the IGBT more stable and reliable.

[0061] Embodiment 1:

[0062] Based on the above electromagnetic heating IGBT driving circuit, it is further configured that the first driving module is started prior to the second driving module according to the driving signal.

[0063] In this embodiment, the first driving module includes an acceleration circuit 41 connected between the first driving module input terminal and the driving signal input terminal. The first driving module obtains the driving signal through the acceleration circuit in priority to the second driving module.

[0064] Furthermore, the acceleration circuit includes an acceleration capacitor connected in parallel in the acceleration circuit, and the driving signal is input into the first driving module after being accelerated by the acceleration capacitor.

[0065] The voltage regulation module includes a voltage dividing circuit 61,

[0066] The first driving module controls the voltage divider circuit to enable according to the driving signal, so as to adjust the voltage at the input end of the push-pull module to the voltage divided by the voltage divider circuit;

[0067] The second driving module turns off the voltage dividing circuit according to the driving signal to adjust the voltage at the input end of the push-pull module to the driving power supply voltage that has not been divided by the voltage dividing circuit.

[0068] Specifically, the overall block diagram of the IGBT driving circuit of this embodiment is as follows: Figure 2 As shown, the specific circuit diagram of the IGBT drive circuit is as follows Figure 3 shown.

[0069] After the driving signal is input into the first driving module and the second driving module through the driving signal input terminal, there is a certain time difference between the start-up of the first driving module and the second driving module, and the driving time difference is T1. Within the T1 time difference range, the voltage at the input terminal of the push-pull module is controlled by the first driving module, which is the voltage after the voltage divider circuit. Within the T2 time after reaching the T1 time, the voltage at the input terminal of the push-pull module is controlled by the second driving module, which is the driving power supply voltage that has not been divided by the voltage divider circuit, so that each driving signal is automatically driven, firstly the IGBT is soft-started with the voltage after the voltage divider, and then the IGBT is driven to conduct normally with the normal driving power supply voltage. The time difference T1 is controlled by the acceleration circuit.

[0070] Combination Figure 3 It can be seen that the first driving module includes a capacitor C1, a resistor R2, a resistor R6, a resistor R8, a resistor R9, a resistor R10, a switch element Q4 and a Zener diode ZD2; the second driving module includes a resistor R2, a resistor R3, a resistor R5, a resistor R6, a resistor R10, a switch element Q2 and a Zener diode ZD2; the voltage divider circuit includes a resistor R2 and a resistor R4; and the push-pull module includes a resistor R1, a resistor R4, a resistor R7, a resistor R11, a resistor R12, a capacitor C2, a switch element Q1, a switch element Q3 and a Zener diode ZD1.

[0071] Among them, one end of the resistor R5 is connected to the base of the switch element Q2, and the other end of the resistor R5 is connected to the drive signal input end. The collector of the switch element Q2 is connected to the base of the switch element Q1 through the resistor R3, and the emitter of the switch element Q2 is grounded. The resistor R8 and the capacitor C1 are connected in parallel to form an acceleration circuit. The capacitor C1 here is the acceleration capacitor. The drive signal can be accelerated to the switch element Q2 through the capacitor C1. The input end of the acceleration circuit is connected to the drive signal input end, and the output end of the acceleration circuit is connected to the base of the switch element Q4. The output end of the acceleration circuit is also grounded through the resistor R9. The collector of the switch element Q4 is connected to the driving power supply VCC through the resistor R2, and the collector of the switch element Q4 is also connected to the input end of the push-pull module, that is, the base of the switch element Q1 and the base of the switch element Q3. The emitter of the switch element Q4 is grounded. A resistor R10 and a voltage stabilizing diode ZD2 are also connected in parallel between the input end of the acceleration circuit and the emitter of the switch element Q4, and the input end of the acceleration circuit is also connected to the driving power supply through the resistor R6. The collector of the switch element Q1 is also connected to the driving power supply VCC through the resistor R1, the emitter of the switch element Q1 is connected to the emitter of the switch element Q3, the collector of the switch element Q3 is grounded through the resistor R12, and the base of the switch element Q3 is also connected to the capacitor C1, and the capacitor C1 is also grounded through the resistor R11. The emitter of the switch element Q1 and the emitter of the switch element Q3 are also connected to one end of the resistor R4 at the same time, and the other end of the resistor R4 is connected to the base of the IGBT. A resistor R7 and a voltage stabilizing diode ZD1 are connected in parallel between the base of the IGBT and the emitter of the IGBT.

[0072] In combination with the above circuit connection structure, it can be known that when the driving signal is at a high level, the switch element Q4 in the first driving module is turned on, and the collector voltage of the switch element Q4 is the turn-on voltage of the switch element Q4, which is generally between 0.1 and 0.7V. At this time, the switch element Q2 is in a saturated state, the switch element Q1 in the push-pull module is turned off, and the switch element Q3 is turned on, so that the base voltage of the IGBT is maintained at 0V.

[0073] At the moment when the driving signal is switched from high level to low level, within the time range of T1, because the base of the switch element Q4 in the first driving module is connected to the acceleration circuit composed of the resistor R8 and the capacitor C1, the first driving module receives the driving signal first and starts to work, the switch element Q4 will be quickly cut off, the switch element Q2 will be switched from the saturation state to the on state, and the base voltage of the push-pull module input end, that is, the switch element Q1, will become the voltage after the voltage division by the resistor R2 and the resistor R3. The voltage value after the voltage division is specifically U 分压后 =U VCC*R3 / (R2+R3). At this time, the switch element Q1 in the push-pull module is in the on state, the switch element Q3 is in the off state, and the base voltage U b =U 分压后 -0.7.

[0074] In the time range from T1 to T2, the second driving module receives the driving signal, and the switch element Q2 in the second driving module is converted to the cut-off state, making the voltage divider circuit invalid. At this time, the switch element Q4 remains in the cut-off state, and the base voltage of the switch element Q1 is converted into the driving power supply voltage. The IGBT base voltage U b =U VCC -0.7.

[0075] After reaching T2 time, the driving signal is converted from low level to high level. At the moment when the driving signal is converted from low level to high level, because the base of the switching element Q4 of the first driving module is connected to the acceleration circuit composed of the resistor R8 and the capacitor C1, the switching element Q4 will be quickly turned on, and the turn-on speed is faster than the turn-on speed of the switching element Q2 in the second driving module, and there will be no intermediate state, so that the switching element Q1 in the push-pull circuit is turned off and the switching element Q3 is turned on, so that the IGBT base voltage is 0, and the IGBT is quickly turned off. This stage lasts for T3 time in total.

[0076] The comparison of the change curves of the drive signal and the IGBT base voltage in this embodiment is as follows: Figure 4 shown.

[0077] In this embodiment, the voltage U after being divided by the voltage divider circuit 分压后 The adjustment can be achieved by adjusting the resistance values ​​of the resistor R2 and the resistor R3, and the switching speed of the voltage before and after the voltage division can be further adjusted by adjusting the resistance values ​​and capacitance values ​​of the resistor R11 and the capacitor R2.

[0078] The capacitance of the capacitor C1 in the acceleration circuit is between 1pf and 1uf, the resistance of R8 is between 1 and 500K, and the switching elements Q1, Q2, Q3 and Q4 include but are not limited to switching devices such as triodes and MOS tubes. The voltage regulator voltage of the voltage regulator diode ZD1 must be less than or equal to the driving power supply voltage U VCC , the voltage regulator diode ZD2 needs to be less than or equal to the maximum voltage of the drive signal. The capacitance of capacitor C2 is between 1pf and 1uf, and the resistance of resistor R11 is between 1 and 500K. The resistance of the remaining resistors R1, R4 and R12 are all set between 0 and 500K.

[0079] When setting the parameters of the resistors R6, R8, R9 and R10, it is necessary to ensure that they match each other so that when there is no driving signal, the voltage at the driving signal position can put the switch element in the on state.

[0080] Embodiment 2:

[0081] The circuit structure and basic circuit of this embodiment are basically the same as those of Embodiment 1, except that:

[0082] The first driving module is not provided with an acceleration circuit, and the second driving module includes a delay circuit 51 connected between the second driving module input terminal and the driving signal input terminal. The second driving module obtains the driving signal later than the first driving module through the delay circuit.

[0083] Specifically, the overall structure of the IGBT driving circuit in this embodiment is as follows: Figure 5 shown.

[0084] After the driving signal is input into the first driving module and the second driving module through the driving signal input terminal, there is a certain time difference between the start-up of the first driving module and the second driving module, and the driving time difference is T1. Within the T1 time difference range, the voltage at the input terminal of the push-pull module is controlled by the first driving module, which is the voltage after the voltage divider circuit. Within the T2 time after reaching the T1 time, the voltage at the input terminal of the push-pull module is controlled by the second driving module, which is the driving power supply voltage that has not been divided by the voltage divider circuit. When each driving signal is driven automatically, the IGBT is first soft-started with the voltage after the voltage divider, and then the IGBT is driven to conduct normally with the normal driving power supply voltage. The time difference T1 is controlled by the delay circuit, and in this embodiment, the time difference T1 is between 0.1 and 20us.

[0085] In this embodiment, a two-stage delay circuit is specifically set up. Each stage of the delay circuit includes a switch element and a current limiting element connected in series in the delay circuit. The drive signal is delayed by the current limiting element and the switch element connected in series and then input into the second drive module.

[0086] Specifically, the circuit diagram of the IGBT driving circuit of this embodiment is as follows: Figure 6 shown.

[0087] Combination Figure 6It can be seen that the first driving module includes resistor R2, resistor R10, resistor R12, resistor R13, Zener diode ZD2 and switch element Q6, the second driving module includes resistor R2, resistor R3, resistor R4, resistor R5, resistor R7, resistor R8, resistor R9, resistor R10, resistor R13, switch element Q2, switch element Q3, switch element Q4 and Zener diode ZD2, the voltage divider circuit includes resistor R2 and resistor R3, and the push-pull module includes resistor R1, resistor R6, resistor R11, resistor R14, resistor R15, switch element Q1, switch element Q5, capacitor C1 and Zener diode ZD1.

[0088] Among them, one end of the resistor R9 is connected to the driving signal input end, and the other end of the resistor R9 is connected to the base of the switching element Q4. The collector of the switching element Q4 is connected to the driving power supply VCC through the resistor R5. At the same time, the collector of the switching element Q4 is also connected to the base of the switching element Q3 through the resistor R8. The collector of the switching element Q3 is connected to the driving power supply VCC through the resistor R4. At the same time, the collector of the switching element Q3 is also connected to the base of the switching element Q2 through the resistor R7. The collector of the switching element Q2 is connected to the base of the switching element Q1 through the resistor R3, and the emitters of the switching element Q4, the switch Q3 and the switching element Q2 are all grounded.

[0089] The resistor R5, the resistor R9 and the switch element Q4 constitute a first-stage delay circuit, and the resistor R4, the resistor R8 and the switch element Q3 constitute a second-stage delay circuit.

[0090] The driving signal input terminal is also connected to one end of the resistor R12, the other end of the resistor R12 is also connected to the base of the switch element Q6, the other end of the resistor R12 is also connected to the driving power supply through the resistor R10, and a resistor R13 and a voltage stabilizing diode ZD2 are also connected in parallel between the other end of the resistor R12 and the emitter of the switch element Q6, the collector of the switch element Q6 is connected to the driving power supply VCC through the resistor R2, the collector of the switch element Q6 is also connected to the input end of the push-pull module, that is, the base of the switch element Q1 and the base of the switch element Q5, and the emitter of the switch element Q6 is grounded. And the other end of the resistor R12 is also connected to the driving power supply VCC through the resistor R10.

[0091] The collector of the switch element Q1 is also connected to the driving power supply VCC through the resistor R1, the emitter of the switch element Q1 is connected to the emitter of the switch element Q5, the collector of the switch element Q5 is grounded through the resistor R15, the base of the switch element Q5 is also connected to the capacitor C1, and the capacitor C1 is also grounded through the resistor R14. The emitter of the switch element Q1 and the emitter of the switch element Q5 are also connected to one end of the resistor R6 at the same time, and the other end of the resistor R6 is connected to the base of the IGBT. A resistor R11 and a voltage regulator diode ZD1 are also connected in parallel between the base of the IGBT and the emitter of the IGBT.

[0092] Specifically, in combination with the above circuit connection structure, it can be known that when the driving signal is at a high level, the switch element Q6 in the first driving module is turned on, and the collector voltage of the switch element Q6 is the turn-on voltage of the switch element Q6, which is generally between 0.1 and 0.7V. At this time, the switch element Q2 is in a saturated state, the switch element Q1 in the push-pull module is turned off, and the switch element Q5 is turned on, so that the base voltage of the IGBT is maintained at 0V.

[0093] At the moment when the driving signal is converted from a high level to a low level, the first driving module starts to work after receiving the driving signal. The second driving signal cannot receive the driving signal within the T1 time range due to the existence of the delay circuit. Therefore, within the T1 time range, the switch element Q6 in the first driving module is normally turned off, and the switch element Q2 is converted from a saturated state to a conductive state. The input end of the push-pull module, that is, the base voltage of the switch element Q1 becomes a voltage processed by the voltage division of the resistor R2 and the resistor R3. The voltage value after the voltage division is specifically U after voltage division = U VCC *R3 / (R2+R3). At this time, the switch element Q1 in the push-pull module is in the on state, the switch element Q5 is in the off state, and the base voltage Ub of the IGBT is U 分压后 -0.7.

[0094] In the time range from T1 to T2, the second driving module receives the driving signal, and the switch element Q2 in the second driving module is converted to the cut-off state, making the voltage divider circuit invalid. At this time, the switch element Q6 remains in the cut-off state, and the base voltage of the switch element Q1 is converted into the driving power supply voltage. The IGBT base voltage U b =U VCC -0.7.

[0095] After reaching T2 time, the drive signal is converted from low level to high level, the switch element Q6 is turned on, the switch element Q2 is in saturation state, the switch element Q1 in the push-pull module is turned off, and the switch element Q5 is turned on, so that the base voltage of the IGBT is maintained at 0V. This stage lasts for a total of T3 time.

[0096] In this embodiment, the variation curves of the driving signal and the driving voltage are as follows: Figure 7 shown.

[0097] The delay time of the delay circuit in this embodiment can be achieved by adjusting the resistance values ​​of resistors R4, R5, R7, R8 and R9, where resistors R4, R5, R7, R8 and R9 are all used as current limiting elements to adjust the base current of the switch element Q2, thereby achieving the purpose of controlling its conduction time. In addition to adjusting the resistance values ​​of these current limiting elements, different switch elements have different conduction time characteristics, and the delay time can also be adjusted by adjusting the types of switch elements Q2, switch elements Q3 and switch elements Q4.

[0098] In addition, the switch element Q1 , the switch element Q2 , the switch element Q3 , the switch element Q4 , the switch element Q5 and the switch element Q6 in this embodiment also include but are not limited to switch devices such as triodes and MOS tubes.

[0099] The delay circuit is not limited to the delay circuit formed by the current limiting element and the switch element, and can also be a delay in the form of a Schmitt trigger, a voltage follower, a digital circuit delay, etc.

[0100] Embodiment 3:

[0101] The circuit structure and basic circuit of this embodiment are basically the same as those of Embodiment 1 or Embodiment 2, except that:

[0102] The voltage regulation module is also provided with a control signal input terminal 8, which receives an external control signal to shut down the voltage regulation module when the second driving module is started; and to control the voltage regulation module to be enabled when the first driving module is started. In addition, the voltage regulation module is not provided with a voltage divider circuit, but is replaced by a power supply unit 62 controlled by an external control signal. The power supply unit includes a power supply whose supply voltage is less than the driving power supply, and the control signal input terminal directly controls the opening and closing of the power supply unit. Specifically, the overall block diagram of the IGBT driving circuit of this embodiment is as follows: Figure 8 shown.

[0103] The power supply unit is arranged between the first driving module and the input end of the push-pull module. After the first driving module is started, the external control signal will control the power supply of the power supply unit to turn on when the first driving module is started, so that the voltage at the input end of the push-pull module is provided by the power supply of the power supply unit. After the second driving module is started, the external control signal will control the power supply of the power supply unit to turn off when the second driving module is started, so that the voltage at the input end of the push-pull module is provided by the driving power supply.

[0104] The same as in Example 1 and Example 2 is that after the driving signal is input into the first driving module and the second driving module through the driving signal input terminal, there is a certain time difference between the start-up of the first driving module and the second driving module, and the driving time difference is T1. Within the time difference range of T1, the voltage at the input terminal of the push-pull module is controlled by the external control signal and is the power supply voltage of the power supply unit. Within the time T2 after reaching the time T1, the voltage at the input terminal of the push-pull module is controlled by the external control signal and converted into the voltage of the driving power supply, so that each driving signal is automatically driven, first soft-starting the IGBT with a smaller voltage, and then driving the IGBT to conduct normally with the normal driving power supply voltage. And the time difference T1 can be controlled by an acceleration circuit or a delay circuit.

[0105] In this embodiment, the start-up time difference between the first driving module and the second driving module can be achieved by using an acceleration circuit to enable the first driving module to be turned on first, or by using a delay circuit to enable the second driving module to be turned on with delay, and the on and off logic of each component in the first driving module and the second driving module is consistent with that in Embodiment 1 or Embodiment 2.

[0106] Embodiment 4:

[0107] The circuit structure and basic circuit of this embodiment are basically the same as those of Embodiment 1 and Embodiment 2, except that:

[0108] The first driving circuit is not provided with an acceleration circuit, and the second driving circuit is not provided with a delay circuit, but a digital clock module 7 is additionally provided, and the digital clock module is provided between the driving signal input terminal and the input terminals of the first driving module and the second driving module;

[0109] The first driving module and the second driving module control the voltage regulating module to enable or disable the voltage regulating module according to the driving signal passing through the digital clock module. Specifically, the overall block diagram of the IGBT driving circuit of this embodiment is as follows: Fig. 9 shown.

[0110] The digital clock module can directly input the driving signal into the first driving module and the second driving module at different input times according to the preset time difference, and the digital clock module realizes the start-up time difference between the first driving module and the second driving module.

[0111] In this embodiment, the voltage regulation module can implement voltage regulation by a voltage divider module, or by a power supply unit.

[0112] After the driving signal is input into the digital clock module through the driving signal input terminal, the digital clock module first inputs the driving signal into the first driving module. The first driving module starts after receiving the driving signal. The voltage at the input terminal of the push-pull module is controlled by the first driving module, which is the voltage after the voltage divider circuit, or the voltage of the power supply in the power supply unit. After the time when the driving signal is input into the first driving module reaches time T1, the digital clock module inputs the driving signal into the second driving module. The second driving module starts after receiving the driving signal. The voltage at the input terminal of the push-pull module is controlled by the second driving module. The voltage divider circuit fails, or the power supply unit is turned off, and the voltage at the input terminal of the push-pull module is converted into the voltage of the driving power supply.

[0113] In this embodiment, the on and off logic of each component in the first driving module is consistent with that in the second embodiment, while the on and off logic of each component in the second driving module is consistent with that in the first embodiment.

[0114] Embodiment 5:

[0115] Combination Figure 4 and Figure 7 It can be seen that, through the adjustment of the start-up time difference between the first drive module and the second drive module in the above embodiments, the change curve of the IGBT base voltage presents a smooth rising feature. Through the adjustment of this embodiment, the IGBT base voltage can be increased in a step-by-step manner. Specifically, this embodiment is achieved in the following ways:

[0116] An acceleration circuit is arranged between the first driving module input terminal and the driving signal input terminal, and a deceleration circuit is arranged between the second driving module input terminal and the driving signal input terminal.

[0117] At the moment when the driving signal switches from a high level to a low level, in the first period of time within the T1 time range, because the first driving module is provided with an acceleration circuit, the first driving module will receive the driving signal first and start working, and the base voltage at the input end of the push-pull module becomes the voltage regulated by the voltage regulating module.

[0118] At this time, since a multi-stage deceleration circuit is also provided in the second driving module, the base voltage of the push-pull circuit will be maintained at the voltage adjusted by the voltage regulating module for a period of time, that is, in the latter period of time within the T1 time range, the base voltage of the push-pull circuit will be maintained at the voltage adjusted by the voltage regulating module unchanged. When the T1 time is reached and the second driving module is started, the voltage at the input end of the push-pull module will be switched to the control of the second driving module, so that the base voltage of the push-pull circuit changes, thereby making the base voltage of the IGBT show a step-like rising characteristic.

[0119] Alternatively, the start-up time difference between the first driving module and the second driving module is realized by the digital clock module, and the start-up time difference preset in the digital clock module is further increased.

[0120] The digital clock module can directly input the driving signal to the first driving module and the second driving module at different input times according to the preset time difference, and further increase the interval time of transmitting the driving signal, so that the IGBT base voltage has a step-like rising characteristic.

[0121] Embodiment 6:

[0122] An electromagnetic cooking appliance includes a main control circuit for controlling the operation of the electromagnetic cooking appliance, the cooking appliance includes a first power working mode and a second power working mode, the power of the second working mode is greater than the power of the first working mode, and the power of the first power working mode is not greater than 600 watts, the main control circuit includes an IGBT driving circuit in any of the above embodiments, so that the first power working mode and the second power working mode are both continuous heating modes. The IGBT driving circuit is integrated into the main control circuit to improve its convenience of use and reduce its cost, and the main control circuit uses the IGBT driving circuit in the present invention to enable the electromagnetic cooking appliance to achieve continuous heating cooking regardless of whether it is in the second working mode with a larger power or the first working mode with a smaller power, especially in the first working mode with a smaller power, compared with the intermittent heating mode used in the prior art, the user experience is greatly optimized, and at the same time, the voltage and current at the moment of IGBT conduction are reduced, thereby ensuring the service life of the electromagnetic cooking appliance.

[0123] Furthermore, the main control circuit includes a single chip microcomputer, and each module of the IGBT driving circuit is integrated into the single chip microcomputer.

[0124] It should be noted that, in any of the above embodiments, the electromagnetic cooking appliance includes any one of an induction cooker, an electric rice cooker, an electric pressure cooker, and an electric hot pot.

[0125] In the description of the present invention, it should be noted that the "electromagnetic cooking appliance" mentioned in the present invention may include any cooking equipment that can cook food and to which the technical solution of the present invention can be applied, including but not limited to induction cookers, electric pressure cookers, electric rice cookers, and electric hot pots.

[0126] Taking a rice cooker as an example, during the entire cooking process of cooking rice, there is a stage where low-power heating is required. The rice cooking procedure includes a heating stage, a boiling stage, and a simmering stage. In the heating stage, high power is mainly used to quickly heat the temperature to the preset temperature, and in the boiling stage, low power or intermittent heating is mainly used to avoid overflowing the pot. The traditional low-power intermittent heating mode mainly achieves low-power heating by controlling the proportion of cooking time of the heating device in the cooking stage. For example, within the T time period, a heating device with a power of 1000W always keeps working to achieve high-power heating with a heating power of 1000W per unit time. When low-power heating with a heating power of 300W per unit time is required, the 1000W heating device is controlled to work for 0.3T time within the T time period, and stops working for the remaining 0.7T time, thereby achieving low-power heating with a heating power of 300W per unit time. Since the heating device actually still heats at a power of 1000W during the boiling stage, but its working time is shortened, the traditional low-power intermittent heating mode will cause the rice cooker to easily overflow during the period when the heating device is in working state during the boiling stage. The solution of the present invention can enable the rice cooker to achieve low-power continuous heating during the boiling stage, that is, the IGBT is controlled by the technical solution of the present invention within the T time so that the heating device can continuously work at a power of 300W, thereby achieving a low-power heating effect in the true sense. Since the heating device maintains a power of 300W at any time during the boiling stage, the heating power is always low, so the occurrence of overflow can be avoided to a large extent.

[0127] In addition, when cooking hot pot or soup, traditional low-power intermittent heating is used. When the heating device is working, the noise is relatively large, and the intermittent working mode gives the user a poor experience. Relatively speaking, the technical solution of the present invention can always maintain stable low-power heating when cooking soup and hot pot, while ensuring that the IGB is not easily damaged, and optimizing the user experience.

[0128] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. An IGBT driving circuit for electromagnetic heating, comprising: A driving signal input terminal, used to receive a driving signal for driving the IGBT; IGBT push-pull module, used to control the conduction state of IGBT; A driving power supply, used to supply power to the IGBT driving circuit; It is characterized by further comprising a first driving module, a second driving module, and a voltage regulating module. The output end of the voltage regulating module is connected to the input end of the push-pull module; The input ends of the first driving module and the second driving module are connected to the driving signal input end to obtain the driving signal; The first driving module controls the voltage regulating module to enable according to the driving signal, so as to adjust the voltage at the input end of the push-pull module; The second driving module turns off the voltage regulating module according to the driving signal to connect the driving power supply to the input end of the push-pull module.

2. An IGBT driving circuit for electromagnetic heating according to claim 1, characterized in that: The first driving module is activated prior to the second driving module according to the driving signal.

3. The IGBT driving circuit for electromagnetic heating according to claim 1, characterized in that: The first driving module comprises an acceleration circuit connected between an input terminal of the first driving module and an input terminal of a driving signal. The first driving module obtains the driving signal through the acceleration circuit in priority to the second driving module.

4. The IGBT driving circuit for electromagnetic heating according to claim 3, characterized in that: The acceleration circuit includes an acceleration capacitor connected in parallel in the acceleration circuit, and the driving signal is input into the first driving module after being accelerated by the acceleration capacitor.

5. The IGBT driving circuit for electromagnetic heating according to claim 1, characterized in that: The second driving module includes a delay circuit connected between an input terminal of the second driving module and an input terminal of a driving signal. The second driving module obtains the driving signal later than the first driving module through the delay circuit.

6. The electromagnetic heating IGBT driving circuit according to claim 5, characterized in that: The delay circuit is provided with at least one stage, and each stage of the delay circuit includes a switch element and a current limiting element connected in series in the delay circuit. The driving signal is input into the second driving module after being delayed by the current limiting element and the switch element connected in series.

7. The IGBT driving circuit for electromagnetic heating according to claim 1, characterized in that: It also includes a digital clock module, which is arranged between the driving signal input terminal and the input terminals of the first driving module and the second driving module; The first driving module and the second driving module control the voltage regulating module to enable or disable the voltage regulating module according to the driving signal passing through the digital clock module.

8. The electromagnetic heating IGBT driving circuit according to claim 1, characterized in that: The voltage regulation module includes a voltage dividing circuit. The first driving module controls the voltage divider circuit to enable according to the driving signal, so as to adjust the voltage at the input end of the push-pull module to the voltage divided by the voltage divider circuit; The second driving module turns off the voltage dividing circuit according to the driving signal to adjust the voltage at the input end of the push-pull module to the driving power supply voltage that has not been divided by the voltage dividing circuit.

9. The electromagnetic heating IGBT driving circuit according to claim 1, characterized in that: It also includes a control signal input end of the voltage regulation module, which receives an external control signal to shut down the voltage regulation module when the second driving module is started; and controls the voltage regulation module to be enabled when the first driving module is started.

10. An electromagnetic cooking appliance, comprising a main control circuit for controlling the operation of the electromagnetic cooking appliance, the cooking appliance comprising a first power operating mode and a second power operating mode, the power of the second operating mode being greater than the power of the first operating mode, and the power of the first power operating mode being no greater than 600 watts, characterized in that: The main control circuit is provided with the IGBT driving circuit according to any one of claims 1 to 9, so that the first power operating mode and the second power operating mode are both continuous heating modes.

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