A protection circuit, a control method thereof, a variable frequency circuit and an electric device

Abstract

The application provides a protection circuit, a control method thereof, a frequency conversion circuit and a power utilization device, which comprise a control circuit, an insulated gate bipolar transistor and a discharge circuit connected with the control circuit respectively, wherein the discharge circuit is also connected with the insulated gate bipolar transistor; the control circuit is used for controlling and detecting the on-off state of the insulated gate bipolar transistor, and controlling the working state of the discharge circuit according to the on-off state of the insulated gate bipolar transistor; and the discharge circuit is used for consuming the stray inductance current of the emitter of the insulated gate bipolar transistor. The stray inductance current generated by the emitter of the IGBT can be discharged through the discharge circuit by adding the discharge circuit, thereby solving the problem of the parasitic turn-on of the IGBT, ensuring the accurate turn-on of the IGBT without sacrificing the turn-on speed of the device, further improving the stability of the system operation, and prolonging the service life of the components.

Description

Technical Field

[0001] This invention relates to the field of protection circuit design technology, specifically to a protection circuit and its control method, a frequency converter circuit, and electrical equipment. Background Technology

[0002] Currently, IGBTs (Insulated Gate Bipolar Transistors) are widely used in electric drive and motor drive systems.

[0003] Due to the demand for high speeds, IGBTs are switching at increasingly faster frequencies. As the switching frequency increases, the impact of IGBT parasitic parameters on their switching characteristics also becomes more significant. The voltage and current induced by these parasitic parameters can impose considerable stress on the switching device, potentially leading to component damage. Among these parasitic parameters, Miller capacitance and stray inductance have the greatest impact on IGBTs.

[0004] Due to the presence of Miller capacitance and emitter stray inductance, an IGBT that has been turned off may turn on again within a short period of time. This phenomenon of an IGBT turning on again shortly after being turned off is called parasitic conduction.

[0005] If it exists in an IGBT module with upper and lower bridges, parasitic conduction can cause the upper and lower bridges to shoot through, thereby causing a power supply short circuit fault.

[0006] Currently, common methods to prevent parasitic conduction in IGBTs include altering the IGBT's turn-on and turn-off speeds, or applying a negative voltage to the gate to accelerate the device's turn-off speed. The former sacrifices the IGBT's high switching speed, which does not meet the requirements of high-speed switching applications, while the latter requires an additional negative voltage.

[0007] Therefore, there is an urgent need for a method to solve the parasitic turn-on problem of IGBTs, so as to ensure the accuracy of IGBT turn-on and the normal operation of the system without sacrificing the turn-on speed of the devices. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a protection circuit and its control method, a frequency conversion circuit, and electrical equipment to solve the technical problem of parasitic IGBT turn-on by sacrificing the high switching speed of IGBT in the prior art.

[0009] To achieve the above-mentioned technical objectives, according to a first aspect of the present invention, the present invention provides a protection circuit, comprising:

[0010] A control circuit, and an insulated gate bipolar transistor and a discharge circuit respectively connected to the control circuit, wherein the discharge circuit is also connected to the insulated gate bipolar transistor;

[0011] The control circuit is used to control and detect the on / off state of the insulated gate bipolar transistor, and control the working state of the discharge circuit according to the on / off state of the insulated gate bipolar transistor.

[0012] The discharge circuit is used to dissipate stray inductance current at the emitter of the insulated gate bipolar transistor.

[0013] Specifically, the control circuit includes a control chip and a drive circuit, the control chip and the drive circuit are controlled to be connected, and the drive circuit is controlled to be connected to an insulated gate bipolar transistor.

[0014] The control chip is used to output a PWM signal to control the on / off state of the insulated gate bipolar transistor through the drive circuit. The control chip is also used to detect the on / off state of the insulated gate bipolar transistor.

[0015] Specifically, the discharge circuit includes:

[0016] The system comprises a first transistor, a second transistor, a second resistor, and a fourth resistor. The emitter of the first transistor is connected to an external power supply signal. The control chip is connected to the base of the first transistor. The collector of the first transistor is connected to one end of the second resistor, and the other end of the second resistor is connected to the base of the second transistor. The emitter of the second transistor is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the emitter of an insulated-gate bipolar transistor (IGBT). The collector of the second transistor is connected to the base of the IGBT.

[0017] Specifically, the discharge circuit further includes:

[0018] A first capacitor, a third resistor, and a second capacitor are connected together. The control chip is connected to one end of the first capacitor. The collector of the first transistor is connected to one end of the third resistor. The other end of the second resistor is connected to one end of the second capacitor. The other ends of the first capacitor, the second capacitor, the third resistor, and the fourth resistor are connected to the emitter of the insulated gate bipolar transistor.

[0019] Specifically, the driving circuit includes:

[0020] An insulated gate bipolar transistor (IGBT) driver chip, a first resistor, a fifth resistor, a sixth resistor, and a first diode are provided. The IGBT driver chip includes an input terminal and an output terminal. The output terminal of the IGBT driver chip is connected to the base of the IGBT through a series connection of the sixth resistor and the first diode. The fifth resistor is connected in parallel with the series connection of the sixth resistor and the first diode.

[0021] Specifically, the output terminal of the insulated gate bipolar transistor driver chip is connected to the cathode of the first diode through a sixth resistor, and the anode of the first diode is connected to the base of the insulated gate bipolar transistor.

[0022] Specifically, the discharge circuit further includes a second diode, the collector of the second transistor is connected to the cathode of the second diode, and the anode of the second diode is connected to the base of the insulated gate bipolar transistor.

[0023] According to a second aspect of the present invention, a control method for a protection circuit is provided, the method comprising:

[0024] S100: Detect whether the insulated gate bipolar transistor is in the off state;

[0025] S200: Output a control signal regarding whether the discharge circuit is working based on the detection results.

[0026] According to a third aspect of the present invention, a frequency converter circuit is provided, the frequency converter circuit comprising:

[0027] The aforementioned protection circuit.

[0028] According to a fourth aspect of the present invention, an electrical appliance is provided, the electrical appliance comprising:

[0029] The frequency conversion circuit described above.

[0030] Specifically, the electrical equipment includes at least one of the following:

[0031] Inverter refrigerators, washing machines, air conditioners, microwave ovens, and LED lights.

[0032] Beneficial effects:

[0033] This invention solves the parasitic turn-on problem of IGBTs by adding a discharge circuit, which allows the stray inductance current generated by the emitter of the IGBT to be discharged through the discharge circuit. This solves the problem of parasitic parameters causing additional switching losses in the IGBT and leading to thermal failure of the components. This invention ensures accurate turn-on of the IGBT without sacrificing the turn-on speed of the device, further improving the stability of system operation and extending the service life of the components. Attached Figure Description

[0034] Figure 1 This is a circuit structure diagram of the protection circuit provided in a specific embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram illustrating the generation principle of stray inductance provided in a specific embodiment of the present invention;

[0036] Figure 3This is a flowchart of the control method for the protection circuit provided in a specific embodiment of the present invention. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0038] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0039] Example 1

[0040] Please see Figures 1-2 The present invention provides a protection circuit, comprising:

[0041] A control circuit, and an insulated gate bipolar transistor G1 and a discharge circuit respectively connected to the control circuit, wherein the discharge circuit is also connected to the insulated gate bipolar transistor G1;

[0042] The control circuit is used to control and detect the on / off state of the insulated gate bipolar transistor G1, and to control the working state of the discharge circuit according to the on / off state of the insulated gate bipolar transistor G1.

[0043] The discharge circuit is used to dissipate the stray inductance current of the emitter of the insulated gate bipolar transistor G1.

[0044] Specifically, the control circuit includes a control chip DSP and a drive circuit, the control chip DSP and the drive circuit are controlled to be connected, and the drive circuit is controlled to be connected to an insulated gate bipolar transistor G1.

[0045] The control chip DSP is used to output PWM signals to control the on / off state of the insulated gate bipolar transistor G1 through the drive circuit. The control chip DSP is also used to detect the on / off state of the insulated gate bipolar transistor G1.

[0046] It should be noted that the control chip is a DSP chip used to output PWM signals.

[0047] Specifically, the discharge circuit includes:

[0048] The system comprises a first transistor V1, a second transistor V2, a second resistor R2, and a fourth resistor R4. The emitter of the first transistor V1 is connected to an external power supply signal. The control chip DSP is connected to the base of the first transistor V1. The collector of the first transistor V1 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to the base of the second transistor V2. The emitter of the second transistor V2 is connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the emitter of an insulated-gate bipolar transistor G1. The collector of the second transistor V2 is connected to the base of the insulated-gate bipolar transistor G1.

[0049] It should be noted that the fourth resistor R4 is the emitter resistor, which is used to dissipate the energy caused by the stray inductance current of the emitter of the insulated gate bipolar transistor G1 when the discharge circuit is working, so as to prevent the IGBT from parasitic turn-on.

[0050] Specifically, the discharge circuit further includes:

[0051] The first capacitor C1, the third resistor R3, and the second capacitor C2 are connected together. The control chip DSP is connected to one end of the first capacitor C1. The collector of the first transistor V1 is connected to one end of the third resistor R3. The other end of the second resistor R2 is connected to one end of the second capacitor C2. The other ends of the first capacitor C1, the second capacitor C2, the third resistor R3, and the fourth resistor R4 are connected to the emitter of the insulated gate bipolar transistor G1.

[0052] Please continue to participate. Figure 1 It is understood that U1 is an insulated-gate bipolar transistor (IGBT) driver chip. The IGBT driver chip U1 includes an input terminal 1 and an output terminal 5. The left input terminal 1 of the IGBT driver chip U1 is connected to the PWM signal of the control chip DSP. The first resistor R1 is a current-limiting resistor; V1 is a first transistor, and V2 is a second transistor; the first capacitor C1 and the second capacitor C2 are filter capacitors; the third resistor R3 and the fourth resistor R4 are emitter resistors; and the sixth resistor R6 is an insulated-gate bipolar transistor. The gate resistor of the insulated gate bipolar transistor G1 is connected to the gate resistor R6 of the insulated gate bipolar transistor G1. The first inductor L1 and the second inductor L2 are the stray inductances of the emitter of the insulated gate bipolar transistor G1. G2 is the lower bridge insulated gate bipolar transistor. VD1 and VD2 are the freewheeling diodes of the insulated gate bipolar transistor G1, where VD1 is the first freewheeling diode and VD2 is the second freewheeling diode. VDC is the DC bus.

[0053] Specifically, the driving circuit includes:

[0054] The insulated gate bipolar transistor (IGBT) driver chip U1, a first resistor R1, a fifth resistor R5, a sixth resistor R6, and a first diode D1 are provided. The output terminal 5 of the IGBT driver chip U1 is connected to the base of the IGBT G1 through the series connection of the sixth resistor R6 and the first diode D1. The fifth resistor R5 is connected in parallel with the series connection of the sixth resistor R6 and the first diode D1.

[0055] Specifically, the output terminal 5 of the insulated gate bipolar transistor driver chip U1 is connected to the cathode of the first diode D1 through the sixth resistor R6, and the anode of the first diode D1 is connected to the base of the insulated gate bipolar transistor G1.

[0056] Specifically, the discharge circuit further includes a second diode D2, the collector of the second transistor V2 is connected to the cathode of the second diode D2, and the anode of the second diode D2 is connected to the base of the insulated gate bipolar transistor G1.

[0057] Please continue reading. Figure 1 It is understood that the working principle of the insulated gate bipolar transistor G1 protection circuit provided by the present invention is as follows:

[0058] Insulated-gate bipolar transistor (IGBT) G1 is the upper bridge IGBT, and IGBT G2 is the lower bridge IGBT. When IGBT G1 is off, current flows through the first freewheeling diode VD1. If IGBT G2 is on at this time, current will flow through the stray inductance L1. The change in current will generate a voltage UE, the value of which is:

[0059] UE = LE·diF / dt

[0060] In the above formula, UE is the voltage generated across the stray inductor L1, LE is the inductance of the stray inductor L1, and iF is the forward current of the diode. We can derive ΔU. If the value of ΔU exceeds the turn-on threshold of the insulated-gate bipolar transistor G1, it will cause the insulated-gate bipolar transistor G1 to be parasiticly turned on. ΔU is expressed as follows:

[0061] △U=UGE-UE=UGE-LE·diF / dt

[0062] Understandably, at this point, the present invention can determine whether the insulated gate bipolar transistor G1 is in the on state by judging whether the control chip DSP sends a PWM wave signal. If the judgment is yes, no processing is required, and normal operation is sufficient. If the judgment is no, the transistor V1 controlling the discharge circuit is turned on, and the current generated by the stray inductor L1 is discharged to the discharge circuit. Therefore, when it is determined that the upper bridge insulated gate bipolar transistor G1 is turned off, the control chip DSP outputs a control signal to set the base of the first diode D1 to a low level, that is, to set the CTRL signal low. At this time, the emitter potential of the first transistor V1 is higher than the base potential, so the first transistor V1 will be turned on. Then the collector of the first transistor V1 is also at a high level, and the base potential of the second transistor V2 is higher than the emitter potential, so the second transistor V2 will also be turned on.

[0063] In this way, the energy generated by the stray inductance L1 can be dissipated through resistor R4. That is, at this time,

[0064] △U=UGE-UE-UR4=UGE-LE·diF / dt-UR4

[0065] The circuit described above can effectively reduce the value of ΔU, keeping it below the IGBT turn-on threshold voltage, thus preventing parasitic turn-on of the insulated gate bipolar transistor G1.

[0066] Example 2

[0067] Please see Figure 3 The present invention provides another embodiment, which provides a control method for an insulated gate bipolar transistor (IGBT) G1 protection circuit. The control method for the IGBT G1 protection circuit includes:

[0068] S100: Detect whether the insulated gate bipolar transistor is in the off state;

[0069] S200: Output a control signal regarding whether the discharge circuit is working based on the detection results.

[0070] S300. If the insulated gate bipolar transistor is detected to be in the on state, control the discharge circuit to disconnect the connection with the emitter of the insulated gate bipolar transistor.

[0071] If the insulated gate bipolar transistor is detected to be in the off state, the discharge circuit is controlled to connect to the emitter of the insulated gate bipolar transistor.

[0072] Specifically, if the insulated gate bipolar transistor G1 is detected to be in the off state, the control chip DSP outputs a control signal to control the base of the first diode D1 to be at a low level.

[0073] It is understood that the control principle of the control method for the insulated gate bipolar transistor G1 protection circuit provided by this invention is as follows:

[0074] Insulated-gate bipolar transistor (IGBT) G1 is the upper bridge IGBT, and IGBT G2 is the lower bridge IGBT. When IGBT G1 is off, current flows through the first freewheeling diode VD1. If IGBT G2 is on at this time, current will flow through the stray inductance L1. The change in current will generate a voltage UE, the value of which is:

[0075] UE = LE·diF / dt

[0076] In the above formula, UE is the voltage generated across the stray inductor L1, LE is the inductance of the stray inductor L1, and iF is the forward current of the diode. We can derive ΔU. If the value of ΔU exceeds the turn-on threshold of the insulated-gate bipolar transistor G1, it will cause the insulated-gate bipolar transistor G1 to be parasiticly turned on. ΔU is expressed as follows:

[0077] △U=UGE-UE=UGE-LE·diF / dt

[0078] Understandably, at this point, the present invention can determine whether the insulated gate bipolar transistor G1 is in the on state by judging whether the control chip DSP sends a PWM wave signal. If the judgment is yes, no processing is required, and normal operation is sufficient. If the judgment is no, the transistor V1 controlling the discharge circuit is turned on, and the current generated by the stray inductor L1 is discharged to the discharge circuit. Therefore, when it is determined that the upper bridge insulated gate bipolar transistor G1 is turned off, the control chip DSP outputs a control signal to set the base of the first diode D1 to a low level, that is, to set the CTRL signal low. At this time, the emitter potential of the first transistor V1 is higher than the base potential, so the first transistor V1 will be turned on. Then the collector of the first transistor V1 is also at a high level, and the base potential of the second transistor V2 is higher than the emitter potential, so the second transistor V2 will also be turned on.

[0079] In this way, the energy generated by the stray inductance L1 can be dissipated through resistor R4. That is, at this time,

[0080] △U=UGE-UE-UR4=UGE-LE·diF / dt-UR4

[0081] The circuit described above can effectively reduce the value of ΔU, keeping it below the IGBT turn-on threshold voltage, thus preventing parasitic turn-on of the insulated gate bipolar transistor G1.

[0082] It is understood that by adding a discharge circuit, the stray inductance current generated by the emitter of the IGBT can be discharged through the discharge circuit, thereby solving the parasitic turn-on problem of the IGBT and solving the problem that parasitic parameters cause additional switching losses in the IGBT, leading to thermal failure of the components. Without sacrificing the turn-on speed of the device, the present invention ensures accurate turn-on of the IGBT, further improving the stability of system operation and extending the service life of the components.

[0083] Example 3

[0084] The present invention also provides a frequency converter circuit, the frequency converter circuit comprising:

[0085] The protection circuit described in Example 1.

[0086] Example 4

[0087] The present invention also provides an electrical appliance, the electrical appliance comprising:

[0088] The frequency conversion circuit described in Example 3.

[0089] Specifically, the electrical equipment includes at least one of the following:

[0090] Inverter refrigerators, washing machines, air conditioners, microwave ovens, and LED lights.

[0091] In a preferred embodiment, this application also provides an electronic device, the electronic device comprising:

[0092] The computer device includes a memory and a processor, wherein the memory stores computer-readable instructions that, when executed by the processor, implement the control method for the protection circuit. The computer device can be broadly categorized as a server, terminal, or any other electronic device with the necessary computing and / or processing capabilities. In one embodiment, the computer device may include a processor, memory, network interface, communication interface, etc., connected via a system bus. The processor of the computer device can be used to provide the necessary computing, processing, and / or control capabilities. The memory of the computer device may include a non-volatile storage medium and internal memory. The non-volatile storage medium may store an operating system, computer programs, etc. The internal memory can provide an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The network interface and communication interface of the computer device can be used to connect and communicate with external devices via a network. When the computer program is executed by the processor, it performs the steps of the method of the present invention.

[0093] This invention can be implemented as a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, causes the steps of the methods of embodiments of the invention to be performed. In one embodiment, the computer program is distributed across multiple network-coupled computer devices or processors, such that the computer program is stored, accessed, and executed in a distributed manner by one or more computer devices or processors. A single method step / operation, or two or more method steps / operations, may be executed by a single computer device or processor or by two or more computer devices or processors. One or more method steps / operations may be executed by one or more computer devices or processors, and one or more other method steps / operations may be executed by one or more other computer devices or processors. One or more computer devices or processors may execute a single method step / operation, or execute two or more method steps / operations.

[0094] Those skilled in the art will understand that the method steps of this invention can be performed by a computer program instructing related hardware, such as a computer device or processor, to perform the steps of this invention when executed. Depending on the context, any references herein to memory, storage, databases, or other media may include non-volatile and / or volatile memory. Examples of non-volatile memory include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), flash memory, magnetic tape, floppy disk, magneto-optical data storage device, optical data storage device, hard disk, solid-state drive, etc. Examples of volatile memory include random access memory (RAM), external cache memory, etc.

[0095] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0096] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A protection circuit, characterized in that, include: A control circuit, and an insulated-gate bipolar transistor and a discharge circuit respectively connected to the control circuit, wherein the discharge circuit is also connected to the insulated-gate bipolar transistor; The control circuit is used to control and detect the on / off state of the insulated gate bipolar transistor (IGBT), and to control the operating state of the discharge circuit based on the on / off state of the IGBT. The discharge circuit is used to dissipate the stray inductance current of the emitter of the insulated gate bipolar transistor. The control circuit includes a control chip and a drive circuit, which are connected in a controllable manner, and the drive circuit is connected in a controllable manner to an insulated gate bipolar transistor. The control chip is used to output a PWM signal to control the on / off state of the insulated gate bipolar transistor through the driving circuit. The control chip is also used to detect the on / off state of the insulated gate bipolar transistor. The discharge circuit includes: The system comprises a first transistor, a second transistor, a second resistor, and a fourth resistor. The emitter of the first transistor is connected to an external power supply signal. The control chip is connected to the base of the first transistor. The collector of the first transistor is connected to one end of the second resistor, and the other end of the second resistor is connected to the base of the second transistor. The emitter of the second transistor is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the emitter of an insulated-gate bipolar transistor (IGBT). The collector of the second transistor is connected to the base of the IGBT.

2. The protection circuit according to claim 1, characterized in that, The discharge circuit also includes: A first capacitor, a third resistor, and a second capacitor are connected together. The control chip is connected to one end of the first capacitor. The collector of the first transistor is connected to one end of the third resistor. The other end of the second resistor is connected to one end of the second capacitor. The other ends of the first capacitor, the second capacitor, the third resistor, and the fourth resistor are connected to the emitter of the insulated gate bipolar transistor.

3. The protection circuit according to claim 1, characterized in that, The driving circuit includes: An insulated gate bipolar transistor (IGBT) driver chip, a first resistor, a fifth resistor, a sixth resistor, and a first diode are provided. The IGBT driver chip includes an input terminal and an output terminal. The output terminal of the IGBT driver chip is connected to the base of the IGBT through a series connection of the sixth resistor and the first diode. The fifth resistor is connected in parallel with the series connection of the sixth resistor and the first diode.

4. The protection circuit according to claim 3, characterized in that, The output terminal of the insulated gate bipolar transistor driver chip is connected to the cathode of the first diode through a sixth resistor, and the anode of the first diode is connected to the base of the insulated gate bipolar transistor.

5. The protection circuit according to claim 2, characterized in that, The discharge circuit further includes a second diode, the collector of the second transistor is connected to the cathode of the second diode, and the anode of the second diode is connected to the base of the insulated gate bipolar transistor.

6. A control method for a protection circuit, characterized in that, The method, applicable to the protection circuit according to any one of claims 1-5, comprises: S100: Detect whether the insulated gate bipolar transistor is in the off state; S200: Output a control signal regarding whether the discharge circuit is working based on the detection results.

7. A frequency converter circuit, characterized in that, The frequency conversion circuit includes: The protection circuit according to any one of claims 1-5.

8. An electrical appliance, characterized in that, The electrical equipment includes: The frequency conversion circuit according to claim 7.

9. The electrical equipment according to claim 8, characterized in that, The electrical equipment includes at least one of the following: Inverter refrigerators, washing machines, air conditioners, microwave ovens, and LED lights.

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