CN215647451U - IGBT protection circuit and electromagnetic heating device - Google Patents

Abstract

The application provides an IGBT protection circuit and electromagnetic heating utensil, this IGBT protection circuit includes: the circuit comprises a control circuit, a driving circuit, an IGBT, a comparison circuit and a clamping circuit; the control circuit outputs a pulse signal to the drive circuit through the first port to control the IGBT to be switched on or switched off, outputs a charging signal to the first input end of the comparison circuit through the second port, and outputs a reference signal to the second input end of the comparison circuit through the third port; the clamping circuit is used for clamping the voltage of the first input end of the comparison circuit; the comparison circuit is used for controlling the IGBT to be turned off through the driving circuit when the voltage of the first input end is larger than the voltage of the second input end. Thus, the overcurrent damage of the IGBT is avoided.

Description

IGBT protection circuit and electromagnetic heating device

Technical Field

The embodiment of the application relates to the technical field of circuits, in particular to an IGBT (insulated gate bipolar transistor) protection circuit and an electromagnetic heating appliance.

Background

An electromagnetic heating appliance is a common household appliance for heating, and when the electromagnetic heating appliance works, an Insulated Gate Bipolar Transistor (IGBT) is controlled to be switched on and off at a high frequency by using a Pulse Width Modulation (PWM) signal, so that a high-frequency alternating current is generated on a heating coil to perform resonance heating.

In an abnormal situation, if the current of the IGBT exceeds a limit value, the IGBT is easily damaged by overcurrent.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides an IGBT protection circuit and an electromagnetic heating device to avoid the damage of IGBT overheating.

In a first aspect, the present application provides an IGBT protection circuit, including: the circuit comprises a control circuit, a driving circuit, an IGBT, a comparison circuit and a clamping circuit;

the control circuit is connected with the drive circuit through a first port, and the drive circuit is connected with the IGBT; the control circuit is connected with the first input end of the comparison circuit through a second port, and the control circuit is connected with the second input end of the comparison circuit through a third port; the clamping circuit is connected with the first input end of the comparison circuit and the IGBT respectively; the driving circuit is connected with the output end of the comparison circuit;

the control circuit outputs a pulse signal to the driving circuit through the first port so as to control the IGBT to be switched on or switched off through the driving circuit;

the control circuit outputs a charging signal to the first input end through the second port and outputs a reference signal to the second input end through the third port;

the clamping circuit is used for clamping the voltage of the first input end;

the comparison circuit is used for controlling the IGBT to be turned off through the driving circuit when the voltage of the first input end is larger than the voltage of the second input end.

The IGBT protection circuit is characterized in that a comparison circuit is additionally arranged between the control circuit and the drive circuit, a clamping circuit is additionally arranged between a first input end of the comparison circuit and the IGBT, when the current of the IGBT is too large, the voltage between a collector and an emitter of the IGBT can also be increased, the voltage clamping of the first input end of the comparison circuit is in a higher voltage range, the voltage of the first input end of the comparison circuit is larger than the voltage of a second input end, the comparison circuit outputs a high-level signal to control the drive circuit to output a low-level signal, the IGBT is turned off, and the overcurrent damage of the IGBT is avoided.

In one embodiment, the comparison circuit includes a comparator and a positive feedback circuit;

the control circuit is connected with the in-phase end of the comparator through the second port and is connected with the inverting end of the comparator through the third port, and the positive feedback circuit is respectively connected with the in-phase end and the output end of the comparator.

Due to the effect of the positive feedback circuit, after the output end of the comparator outputs the high level signal, even if the current of the IGBT is reduced and the voltage of the in-phase end of the comparator is reduced, the output end of the comparator also keeps outputting the high level signal, and the IGBT is continuously turned off by hardware. Thus, the overcurrent damage of the IGBT is avoided.

In one embodiment, the clamp circuit includes: a first diode and a first resistor;

the first end of the first resistor is connected with the in-phase end, the second end of the first resistor is connected with the anode of the first diode, and the cathode of the first diode is connected with the collector of the IGBT.

In one embodiment, the comparison circuit further comprises: a switching circuit and a first filter circuit;

the switch circuit is connected with the second port and the first filter circuit respectively, and the first filter circuit is also connected with the in-phase end.

In one embodiment, the switching circuit includes: a third resistor and a first triode; the first filter circuit includes: a first capacitor and a second resistor;

the first end of the third resistor is connected with the second port, the second end of the third resistor is connected with the base level of the first triode, the emitter level of the first triode is connected with the power supply, and the collector level of the first triode is connected with the first end of the second resistor; and the second end of the second resistor is respectively connected with the first end of the first capacitor and the in-phase end, and the second end of the first capacitor is grounded.

In one embodiment, the positive feedback circuit includes a fourth resistor;

and the first end of the fourth resistor is connected with the in-phase end, and the second end of the fourth resistor is connected with the output end of the comparator.

In one embodiment, the comparison circuit further comprises: a voltage dividing circuit;

the voltage division circuit is connected with the third port and the inverting terminal respectively.

In one embodiment, the comparison circuit further comprises a second filter circuit; the second filter circuit is connected with the output end of the comparator and the driving circuit respectively.

In one embodiment, the method further comprises: an IGBT current detection circuit;

the IGBT current detection circuit is used for detecting the current of the IGBT;

the control circuit is used for controlling the pulse signal output by the first port to be a continuous low level signal, controlling the charging signal output by the second port to be a high level signal and controlling the reference signal output by the third port to be a low level signal when the time length when the current of the IGBT is zero exceeds a preset time length.

The control circuit resets the comparison circuit after the IGBT is determined to be turned off for a period of time by the IGBT current detection circuit, so that the IGBT can be recovered to work, and the phenomenon that the IGBT can not be recovered to work after being turned off is avoided.

In a second aspect, the present application provides an electromagnetic heating appliance comprising an IGBT protection circuit as described in the first aspect and embodiments of the first aspect.

The application provides an IGBT protection circuit and electromagnetic heating utensil, in this IGBT protection circuit, increase comparison circuit between control circuit and drive circuit, increase clamping circuit between comparison circuit's first input and IGBT, when IGBT's electric current is too big, voltage between IGBT's collecting electrode and the projecting pole also can increase, make the voltage clamp of comparison circuit's first input at higher voltage range, make comparison circuit's first input's voltage be greater than the voltage of second input, thereby comparison circuit outputs high level signal and controls drive circuit output low level signal, thereby make IGBT turn-off, avoid IGBT overcurrent damage.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a schematic circuit diagram of an electromagnetic heating appliance in the prior art;

fig. 2 is a first schematic diagram of an IGBT protection circuit provided in an embodiment of the present application;

fig. 3 is a second schematic diagram of an IGBT protection circuit provided in the embodiment of the present application;

fig. 4 is a third schematic diagram of an IGBT protection circuit provided in an embodiment of the present application;

fig. 5 is a fourth schematic diagram of an IGBT protection circuit provided in the embodiment of the present application;

fig. 6 is a fifth schematic diagram of an IGBT protection circuit provided in an embodiment of the present application;

FIG. 7 is a signal timing diagram of the IGBT protection circuit shown in FIG. 6;

fig. 8 is a sixth schematic diagram of an IGBT protection circuit provided in an embodiment of the present application;

fig. 9 is a signal timing diagram of the IGBT protection circuit shown in fig. 8;

fig. 10 is a seventh schematic diagram of an IGBT protection circuit provided in an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it should be construed that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings and are only for convenience in describing the present application and for simplicity in description, but do not indicate or imply that the indicated devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.

Electromagnetic heating appliances, such as induction cookers, electric cookers, and the like, mainly use the principle of high-frequency electromagnetic induction to heat. When the electromagnetic heating appliance works, the controller outputs a PWM signal to control the high-frequency on-off of the IGBT, so that high-frequency alternating current is generated on the heating coil to further perform resonance heating. For example, fig. 1 is a circuit schematic diagram of an electromagnetic heating appliance in the prior art, as shown in fig. 1, a PWM port of a Micro Control Unit (MCU) 10 outputs a PWM signal to a first driving circuit 11, and the first driving circuit 11 is used to control the high-frequency on/off of an IGBT0, wherein the first driving circuit 11 outputs a high-level signal, an IGBT0 is turned on, the first driving circuit 11 outputs a low-level signal, an IGBT0 is turned off, and the IGBT0 is turned on/off at a high frequency to make the first resonant circuit 12 resonate to heat a pot, and the first resonant circuit 12 includes a heating coil and a resonant capacitor (not shown). When the electromagnetic heating appliance works normally, the current of the IGBT0 should be kept below the limit value, however, in some abnormal situations, it may happen that the current of the IGBT0 exceeds the limit value, easily causing overcurrent damage to the IGBT 0.

In order to solve the above problem, an embodiment of the present application provides an IGBT protection circuit, in which a comparison circuit is added between a control circuit and a driving circuit, a clamp circuit is added between a first input end of the comparison circuit and an IGBT, when a current of the IGBT is too large, a voltage between a collector and an emitter of the IGBT is also increased, so that the voltage at the first input end of the comparison circuit is clamped in a higher voltage range, and the voltage at the first input end of the comparison circuit is greater than that at the second input end, so that the comparison circuit outputs a high-level signal to control the driving circuit to output a low-level signal, so that the IGBT is turned off, and the IGBT is prevented from being damaged by overcurrent.

Hereinafter, the IGBT protection circuit provided by the present application will be described in detail by specific embodiments. It is to be understood that the following detailed description may be combined with other embodiments, and that the same or similar concepts or processes may not be repeated in some embodiments. In addition, the IGBT protection circuit provided in the embodiment of the present application may be applied to any other circuit that needs to be protected by an IGBT, except for the above-mentioned electromagnetic heating appliance, and for a circuit in which a controller (control circuit) controls the on/off of an IGBT through a driving circuit, the IGBT protection circuit provided in the embodiment of the present application may be used to avoid the overcurrent damage of the IGBT and achieve the effect of safety protection.

Fig. 2 is a schematic structural diagram of an IGBT protection circuit provided in an embodiment of the present application. As shown in fig. 2, the IGBT protection circuit includes: control circuit 20, drive circuit 21, IGBT, comparison circuit 22, and clamp circuit 23.

The control circuit 20 is connected to the driving circuit 21 through a first port (i.e., a PWM port), and the driving circuit 21 is connected to the IGBT; the control circuit 20 is connected to a first input terminal of the comparison circuit 22 through a second port, and the control circuit 20 is connected to a second input terminal of the comparison circuit 22 through a third port; the clamp circuit 23 is connected with the first input end of the comparison circuit 22 and the IGBT respectively; the driver circuit 21 is connected to an output terminal of the comparator circuit 22.

The control circuit 20 outputs a pulse signal (PWM signal) to the driving circuit 21 through the first port to control the IGBT to be turned on or off through the driving circuit 21; the control circuit 20 outputs the charging signal to the first input terminal of the comparison circuit 22 through the second port, and outputs the reference signal to the second input terminal of the comparison circuit 22 through the third port.

The clamp circuit 23 is used for clamping the voltage of the first input terminal of the comparison circuit 22.

The comparator circuit 22 is used for controlling the IGBT to turn off through the driving circuit 21 when the voltage of the first input terminal is greater than the voltage of the second input terminal.

The control circuit 20 in this embodiment may be an MCU.

In fig. 2, the IGBT protection circuit is applied to an electromagnetic heating appliance as an example, and the IGBT is schematically shown to be connected to the resonant circuit 24, and the resonant circuit 24 is used for resonant heating.

When the electromagnetic heating device works normally, the first port of the control circuit 20 outputs a PWM signal with a certain duty ratio to the driving circuit 21, so as to control the IGBT to perform high-frequency on-off, and thus the resonant circuit 24 performs resonant heating. The duty cycle of the PWM signal is determined according to the heating power.

In the embodiment of the present application, the first port of the control circuit 20 outputs a PWM signal to the driving circuit 21 to drive the IGBT to turn on or off. In addition, the second port of the control circuit 20 outputs the charging signal to the first input terminal of the comparison circuit 22 through the second port, and outputs the reference signal to the second input terminal of the comparison circuit 22 through the third port, the first input terminal of the comparison circuit 22 is connected to the collector of the IGBT through the clamp circuit 23, when the current of the IGBT is within a normal range, that is, the current of the IGBT does not exceed a limit value, the voltage between the collector and the emitter of the IGBT is low, the voltage of the first input terminal of the comparison circuit 22 is clamped within a low voltage range, and the voltage of the first input terminal of the comparison circuit 22 is not greater than the voltage of the second input terminal of the comparison circuit 22, so that the output signal of the output terminal of the comparison circuit 22 is a low level signal, and the low level signal output by the comparison circuit 22 does not affect the driving circuit 21.

However, in some cases, the current of the IGBT is abnormal, the current of the IGBT exceeds the limit value, the voltage between the collector and the emitter of the IGBT is high, the voltage of the first input terminal of the comparison circuit 22 is clamped in a high voltage range, in this case, the voltage of the first input terminal of the comparison circuit 22 is greater than the voltage of the second input terminal of the comparison circuit 22, so that the output signal of the output terminal of the comparison circuit 22 is a high level signal, and the high level signal output by the comparison circuit 22 can control the driving circuit 21 to output a low level signal, so that the IGBT is turned off. Thus, the overcurrent damage of the IGBT is avoided.

The comparison circuit 22 is further explained on the basis of the above-mentioned embodiment.

In one embodiment, referring to fig. 3, the comparison circuit 22 includes a comparator UB and a positive feedback circuit 221.

The control circuit 20 is connected to the non-inverting terminal of the comparator UB through the second port and connected to the inverting terminal of the comparator UB through the third port, and the positive feedback circuit 221 is connected to the non-inverting terminal and the output terminal of the comparator UB, respectively.

When the current of the IGBT is within the normal range, the voltage between the collector and the emitter of the IGBT is low, the voltage at the non-inverting terminal of the comparator UB is clamped within a low voltage range, and the voltage at the non-inverting terminal of the comparator UB is not greater than the voltage at the inverting terminal of the comparator UB, so that the output signal at the output terminal of the comparator UB is a low level signal, and the low level signal output by the comparator UB does not affect the driving circuit 21.

When the current of the IGBT exceeds the limit value, the voltage between the collector and the emitter of the IGBT is high, the voltage at the non-inverting terminal of the comparator UB is clamped in a high voltage range, and the voltage at the non-inverting terminal of the comparator UB is greater than the voltage at the inverting terminal of the comparator UB, so that the output signal at the output terminal of the comparator UB is a high-level signal, and the high-level signal output by the comparator UB can control the driving circuit 21 to output a low-level signal, so that the IGBT is turned off. Meanwhile, due to the positive feedback circuit 221 between the non-inverting terminal and the output terminal of the comparator UB, after the output terminal of the comparator UB outputs a high level signal, even if the current of the IGBT decreases and the voltage of the non-inverting terminal of the comparator UB decreases, the output terminal of the comparator UB keeps outputting the high level signal, and the IGBT is continuously turned off by hardware. Thus, the overcurrent damage of the IGBT is avoided.

In one embodiment, referring to fig. 4, the clamp circuit 23 includes: a first diode D1 and a first resistor R1.

The first end of the first resistor R1 is connected with the non-inverting end of the comparator UB, the second end of the first resistor R1 is connected with the anode of the first diode D1, and the cathode of the first diode D1 is connected with the collector of the IGBT. When the voltage of the non-inverting terminal of the comparator UB is greater than the collector voltage of the IGBT, the first diode D1 is turned on in the forward direction.

When the current of the IGBT is within the normal range, the voltage between the collector and the emitter of the IGBT is low, the first diode D1 is turned on in the forward direction, the voltage at the non-inverting terminal of the comparator UB is clamped within a low voltage range, and the voltage at the non-inverting terminal of the comparator UB is not greater than the voltage at the inverting terminal of the comparator UB, so that the output signal at the output terminal of the comparator UB is a low-level signal, and the low-level signal output by the comparator UB does not affect the driving circuit 21.

When the current of the IGBT exceeds the limit value, the voltage between the collector and the emitter of the IGBT is high, the first diode D1 is turned on in the forward direction, the voltage of the non-inverting terminal of the comparator UB is clamped in a high voltage range, and the voltage of the non-inverting terminal of the comparator UB is greater than the voltage of the inverting terminal of the comparator UB, so that the output signal of the output terminal of the comparator UB is a high level signal, and the high level signal output by the comparator UB can control the driving circuit 21 to output a low level signal, thereby turning off the IGBT. Meanwhile, due to the positive feedback circuit 221 between the non-inverting terminal and the output terminal of the comparator UB, after the output terminal of the comparator UB outputs a high level signal, even if the current of the IGBT decreases and the voltage of the non-inverting terminal of the comparator UB decreases, the output terminal of the comparator UB keeps outputting the high level signal, and the IGBT is continuously turned off by hardware. Thus, the overcurrent damage of the IGBT is avoided.

In one embodiment, referring to fig. 5, the comparison circuit 22 further includes: a switching circuit 222 and a first filtering circuit 223.

The second port of the switch circuit 222 and the control circuit 20 is connected to the first filter circuit 223, and the first filter circuit 223 is further connected to the non-inverting terminal of the comparator UB.

In one embodiment, referring to fig. 5, the comparison circuit 22 further includes: a voltage divider circuit 224.

The voltage divider 224 is connected to the third port of the control circuit 20 and the inverting terminal of the comparator UB, respectively.

In one embodiment, referring to fig. 5, the comparison circuit 22 further comprises a second filter circuit 225; the second filter circuit 225 is connected to the output of the comparator UB and the driver circuit 21, respectively.

The second port of the control circuit 20 outputs a low-level charging signal to the switch circuit 222, so that the switch circuit 222 is turned on, and an output signal of the switch circuit passes through the first filter circuit 223 and then is input to the non-inverting terminal of the comparator UB; when the IGBT is turned on and a certain time has elapsed, a high-level reference signal output from the third port of the control circuit 20 supplies power to the comparator UB, and the reference signal is divided by the voltage dividing circuit 224 and then input to the inverting terminal of the comparator UB; an output signal of the output terminal of the comparator UB is input to the driving circuit 21 after passing through the second filter circuit 225.

In one embodiment, referring to fig. 6, the switching circuit 222 includes: a third resistor R3 and a first triode Q1; the first filter circuit 223 includes: a first capacitor C1 and a second resistor R2.

A first end of the third resistor R3 is connected to a second port (IO 1 port in fig. 6) of the control circuit 20, a second end of the third resistor R3 is connected to a base stage of the first transistor Q1, an emitter stage of the first transistor Q1 is connected to a power supply, and a collector stage of the first transistor Q1 is connected to a first end of the second resistor R2; a second terminal of the second resistor R2 is connected to the first terminal of the first capacitor C1 and the non-inverting terminal of the comparator UB, respectively, and a second terminal of the first capacitor C1 is grounded.

In one embodiment, referring to FIG. 6, the positive feedback circuit 221 includes a fourth resistor R4.

The first end of the fourth resistor R4 is connected with the non-inverting end of the comparator UB, and the second end of the fourth resistor R4 is connected with the output end of the comparator UB.

In one embodiment, referring to fig. 6, the voltage divider circuit 224 includes: a sixth resistor R6 and a fifth resistor R5.

A first end of the sixth resistor R6 is connected to a third port (IO 2 port in fig. 6) of the control circuit 20, a second end of the sixth resistor R6 is connected to a first end of the fifth resistor R5 and an inverting end of the comparator UB, and a second end of the fifth resistor R5 is grounded.

In one embodiment, referring to fig. 6, the second filter circuit 225 includes: a second capacitor C2 and a seventh resistor R7.

A first end of the seventh resistor R7 is connected to the output end of the comparator UB, a second end of the seventh resistor R7 is connected to the first end of the second capacitor C2 and the driving circuit 21, and a second end of the second capacitor C2 is grounded.

In addition, a pull-up resistor R8 is included in the comparator circuit 22 at the output of the comparator UB.

A high-level reference signal output from the third port of the control circuit 20 supplies power to the comparator UB, and the reference signal is divided by the sixth resistor R6 and the fifth resistor R5 and then input to the inverting terminal of the comparator UB; the low-level charging signal output from the second port of the control circuit 20 controls the first transistor Q1 to be turned on, so as to charge the first capacitor C1 after passing through the second resistor R2. The PWM signal output from the first port (PWM port in fig. 6) of the control circuit 20 is input to the drive circuit 21.

Fig. 6 illustrates a possible circuit structure of the driving circuit 21, and in fig. 6, when the PWM signal is at a high level, the driving circuit 21 outputs a low level signal to the IGBT, and the IGBT is turned off; when the PWM signal is at a low level, the drive circuit 21 outputs a high level signal to the IGBT, and the IGBT is turned on.

In fig. 6, after the IGBT is turned on, the control circuit 20 controls the IO1 port to output a low level and controls the IO2 port to output a high level, and the signal timing is as shown in fig. 7. If the current of the IGBT is within the normal range, the voltage between the collector and the emitter of the IGBT is low, the first diode D1 is turned on in the forward direction, the voltage of the first capacitor C1 is clamped within a low voltage range, and the voltage at the non-inverting terminal of the comparator UB is not greater than the voltage at the inverting terminal of the comparator UB, so that the output signal at the output terminal of the comparator UB is a low level signal, the low level signal output by the comparator UB does not affect the output signal of the driving circuit 21, and the output signal of the driving circuit 21 is controlled by the PWM signal.

If the current of the IGBT exceeds the limit value, the voltage between the collector and the emitter of the IGBT is high, the first diode D1 is turned on in the forward direction, the voltage of the first capacitor C1 is clamped in a high voltage range, the voltage of the non-inverting terminal of the comparator UB is greater than the voltage of the inverting terminal of the comparator UB, so that the output signal of the output terminal of the comparator UB is a high level signal, and the high level signal output by the comparator UB can control the driving circuit 21 to output a low level signal, so that the IGBT is turned off. Meanwhile, due to the positive feedback loop of the fourth resistor R4, after the output end of the comparator UB outputs a high-level signal, even if the current of the IGBT decreases and the voltage of the non-inverting end of the comparator UB decreases, the output end of the comparator UB keeps outputting the high-level signal, and the IGBT is continuously turned off through hardware. Thus, the overcurrent damage of the IGBT is avoided.

It should be noted that the circuit structure of the driving circuit 21 is not limited to this, and fig. 8 illustrates another possible circuit structure of the driving circuit 21, and in fig. 8, when the PWM signal is at a high level, the driving circuit 21 outputs a high level signal to the IGBT, and the IGBT is turned on; when the PWM signal is at a low level, the drive circuit 21 outputs a low level signal to the IGBT, and the IGBT is turned off. When the IGBT is turned on, the control circuit 20 controls the IO1 port to output a low level and the IO2 port to output a high level, and the signal timing is as shown in fig. 9. The operation principle of the other circuits in fig. 8 is similar to that in fig. 6, and is not described again.

In one embodiment, referring to fig. 10, the IGBT protection circuit further includes: the IGBT current detection circuit 25.

The IGBT current detection circuit 25 is for detecting the current of the IGBT; the control circuit 20 is configured to control the pulse signal output by the first port to be a continuous low level signal, control the charging signal output by the second port to be a high level signal, and control the reference signal output by the third port to be a low level signal when a duration that a current of the IGBT is zero exceeds a preset duration.

The IGBT current detection circuit 25 is connected to the AD port of the control circuit 20, and when the control circuit 20 determines that the IGBT current detected within the preset time period is zero, it indicates that the IGBT has been turned off for a certain period of time, and it is necessary to reinitialize the PWM controller and related software, etc., the control circuit 20 controls the second port to be at a high level and the third port to be at a low level, so as to reset the comparator UB, and make the comparator UB output a low level signal, so that the output signal of the comparator UB does not affect the output signal of the driving circuit 21. Thereafter, the control circuit 20 can restart the PWM signal output detection pot again, and when the pot is detected, the PWM signal is normally output to heat.

After the control circuit 20 determines that the IGBT is turned off for a period of time through the IGBT current detection circuit 25, the comparison circuit 22 is reset, so that the IGBT resumes operation, and the situation that the IGBT cannot resume operation after being turned off is avoided.

The embodiment of the application also provides an electromagnetic heating appliance, which comprises the IGBT protection circuit in any embodiment, the realization principle and the technical effect of the electromagnetic heating appliance are similar to those of the IGBT protection circuit, and the implementation principle and the technical effect are not repeated herein.

In the present application, the terms "include" and variations thereof may refer to non-limiting inclusions; the term "or" and variations thereof may mean "and/or". The terms "first," "second," and the like in this application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. In the present application, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

Those of ordinary skill in the art will understand that: all or a portion of the steps of implementing the embodiments described above may be performed by hardware associated with program instructions. The program may be stored in a computer-readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the embodiments of the present application, and are not limited thereto; although the embodiments of the present application have been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the embodiments of the present application.

Claims (10)

1. An IGBT protection circuit, comprising: a control circuit (20), a drive circuit (21), an IGBT, a comparison circuit (22) and a clamping circuit (23);

the control circuit (20) is connected with the drive circuit (21) through a first port, and the drive circuit (21) is connected with the IGBT; the control circuit (20) is connected to a first input of the comparison circuit (22) via a second port, and the control circuit (20) is connected to a second input of the comparison circuit (22) via a third port; the clamping circuit (23) is respectively connected with a first input end of the comparison circuit (22) and the IGBT; the driving circuit (21) is connected with the output end of the comparison circuit (22);

the control circuit (20) outputs a pulse signal to the driving circuit (21) through the first port so as to control the IGBT to be switched on or switched off through the driving circuit (21);

the control circuit (20) outputs a charging signal to the first input terminal through the second port and outputs a reference signal to the second input terminal through the third port;

the clamping circuit (23) is used for clamping the voltage of the first input end;

the comparison circuit (22) is used for controlling the IGBT to be turned off through the driving circuit (21) when the voltage of the first input end is larger than the voltage of the second input end.

2. The IGBT protection circuit according to claim 1, wherein the comparison circuit (22) comprises a comparator UB and a positive feedback circuit (221);

the control circuit (20) is connected with the in-phase end of the comparator UB through the second port and is connected with the inverting end of the comparator UB through the third port, and the positive feedback circuit (221) is respectively connected with the in-phase end and the output end of the comparator UB.

3. The IGBT protection circuit according to claim 2, wherein the clamp circuit (23) comprises: a first diode D1 and a first resistor R1;

the first end of the first resistor R1 is connected with the in-phase end, the second end of the first resistor R1 is connected with the anode of the first diode D1, and the cathode of the first diode D1 is connected with the collector of the IGBT.

4. The IGBT protection circuit according to claim 2, wherein the comparison circuit (22) further comprises: a switching circuit (222) and a first filter circuit (223);

the switch circuit (222) and the second port are connected to the first filter circuit (223), and the first filter circuit (223) is further connected to the non-inverting terminal.

5. The IGBT protection circuit according to claim 4, wherein the switching circuit (222) comprises: a third resistor R3 and a first triode; the first filter circuit (223) includes: a first capacitor and a second resistor R2;

a first end of the third resistor R3 is connected to the second port, a second end of the third resistor R3 is connected to a base of the first transistor, an emitter of the first transistor is connected to a power supply, and a collector of the first transistor is connected to a first end of the second resistor R2; a second end of the second resistor R2 is connected to the first end of the first capacitor and the non-inverting end, respectively, and a second end of the first capacitor is grounded.

6. The IGBT protection circuit according to claim 2, wherein the positive feedback circuit (221) includes a fourth resistor R4;

a first terminal of the fourth resistor R4 is connected to the non-inverting terminal, and a second terminal of the fourth resistor R4 is connected to an output terminal of the comparator UB.

7. The IGBT protection circuit according to claim 2, wherein the comparison circuit (22) further comprises: a voltage divider circuit (224);

the voltage dividing circuit (224) is connected to the third port and the inverting terminal, respectively.

8. The IGBT protection circuit according to claim 2, wherein the comparison circuit (22) further comprises a second filter circuit (225);

the second filter circuit (225) is connected to the output of the comparator UB and the driver circuit (21), respectively.

9. The IGBT protection circuit according to any one of claims 1 to 8, further comprising: an IGBT current detection circuit (25);

the IGBT current detection circuit (25) is used for detecting the current of the IGBT;

the control circuit (20) is used for controlling the pulse signal output by the first port to be a continuous low-level signal, controlling the charging signal output by the second port to be a high-level signal and controlling the reference signal output by the third port to be a low-level signal when the duration that the current of the IGBT is zero exceeds the preset duration.

10. An electromagnetic heating device, characterized by comprising an IGBT protection circuit according to any one of claims 1 to 9.

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