Hardware protection circuit of IGBT (Insulated Gate Bipolar Translator)

Abstract

The invention relates to the technical field of electronic circuits, in particular to a hardware protection circuit of an IGBT (Insulated Gate Bipolar Translator), which comprises a switching device and a control circuit, one end of the switching device is connected with the base electrode of the IGBT, and the other end is grounded; the control circuit comprises a first voltage detection module, a second voltage detection module and a comparator module; the first voltage detection module is connected with the IGBT and obtains a voltage signal; the second voltage detection module has a reference voltage; the comparator module is provided with a first input end, a second input end and an output end, and the output end of the first voltage detection module is connected with the first input end; the output end of the second voltage detection module is connected with the second input end; and the output end of the comparator is connected with the switching device and is used for controlling the on-off of the switching device. The hardware protection circuit can control the on-off of the switching device through the comparator module when detecting that the working voltage of the IGBT is abnormal, thereby achieving the quick protection of the IGBT, and reducing the damage risk of the IGBT.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a hardware protection circuit for an IGBT. Background Art

[0002] As an efficient power electronic device, the insulated gate bipolar transistor (IGBT) has been widely used in power conversion and motor control. However, IGBT faces potential risks such as low or high voltage and excessive current during operation. These abnormal conditions may cause IGBT performance degradation or damage. In particular, when the voltage is lower than the normal operating range, the IGBT may not be able to shut down correctly, causing equipment failure or even safety accidents.

[0003] Although there are some protection measures in the current technical solutions, they often rely on complex software algorithms and external monitoring equipment, which not only increases the system cost, but also may not meet the needs of real-time protection due to slow response speed. Therefore, it is particularly important to develop a low-cost, high-efficiency and fast-response IGBT hardware protection circuit. Summary of the invention

[0004] The present application provides an IGBT hardware protection circuit to solve the technical problem of protecting the IGBT device when the driving voltage of the IGBT is too low or too high. The following technical solution is adopted: A hardware protection circuit for an IGBT, comprising a switch device and a control circuit; one end of the switch device is connected to the base of the IGBT, and the other end is grounded; the control circuit comprises a first voltage detection module, a second voltage detection module and a comparator module; The first voltage detection module is connected to the IGBT and obtains a voltage signal, outputs a high level when the voltage signal is greater than zero, and outputs a low level when the voltage signal is equal to zero; The second voltage detection module has a reference voltage, and the second voltage detection module is connected to a power supply and compares the voltage of the power supply with the reference voltage; when the power supply voltage is greater than the reference voltage, a high level is output, and when the power supply voltage is lower than the reference voltage, a low level is output; The comparator module has a first input terminal, a second input terminal and an output terminal. The output terminal of the first voltage detection module is connected to the first input terminal; the output terminal of the second voltage detection module is connected to the second input terminal; the output terminal is connected to the switching device and is used to control the on and off of the switching device.

[0005] By adopting the above technical solution, the hardware protection circuit can control the on and off of the switching device through the comparator module when detecting that the operating voltage of the IGBT is abnormal, thereby realizing rapid protection of the IGBT and reducing the risk of damage thereof.

[0006] Preferably, the first voltage detection module includes a voltage detection resistor and an operational amplifier acquisition unit; the voltage detection resistor is connected to the emitter of the IGBT to detect the operating voltage of the IGBT; the operational amplifier acquisition circuit is connected to the voltage detection resistor to obtain a voltage signal.

[0007] By adopting the above technical solution, the first voltage detection module can accurately detect the operating voltage of the IGBT and provide an accurate voltage signal for subsequent comparison operations.

[0008] Preferably, the second voltage detection module comprises a first voltage input terminal, a first resistor and a first switch tube, the first resistor is connected to the first voltage input terminal, and the first resistor is connected to the second input terminal; One end of the first switch tube is connected to the first resistor, and the other end is grounded. When the first switch tube is turned on, the first resistor is grounded; It also includes a control unit for controlling the on and off of the first switch tube, and the reference voltage is set in the control unit; the input end of the control unit is connected to the power supply, and the output end is connected to the first switch tube.

[0009] By adopting the above technical solution, by controlling the on and off of the first switch tube, the power supply voltage can be compared with the reference voltage, and then a corresponding level signal can be output. This structure is simple and easy to implement, and can effectively monitor the power supply voltage.

[0010] Preferably, the first switch tube is configured as a triode, the base of which is connected to a voltage-stabilizing diode, and the emitter and the collector of which are connected to a first resistor and ground respectively.

[0011] By adopting the above technical solution and using a triode as the first switch tube, the response speed and stability of the circuit can be improved.

[0012] Preferably, the control unit includes a second voltage input terminal, a second resistor and a second switch tube, wherein the second resistor is connected to the switch tube; one end of the second switch tube is connected to the second resistor and the other end is grounded, and when the second switch tube is turned on, the second resistor is grounded; The control unit also includes a voltage stabilizing diode, which provides a reference voltage and has one end connected to the driving power supply and the other end connected to the second switch tube.

[0013] By adopting the above technical solution, the Zener diode can provide a reference voltage. When the IGBT power supply voltage is lower than the reference voltage, it is determined that the voltage is too low. At this time, the Zener diode is disconnected, thereby turning on the second switch tube, thereby making the base of the first switch tube obtain a high level and turn on, providing a low level for the second input terminal of the comparator module.

[0014] Preferably, the second switch tube is configured as a triode, the base of which is connected to a voltage-stabilizing diode, and the emitter and the collector of which are connected to a second resistor and ground respectively.

[0015] By adopting the above technical solution and using a triode as the second switch tube, the response speed and stability of the circuit can be improved.

[0016] Preferably, one end of the voltage stabilizing diode connected to the second switch tube is also connected to a current limiting resistor, and the current limiting resistor is grounded.

[0017] By adopting the above technical solution, setting a current limiting resistor can prevent the voltage regulator diode from being damaged due to excessive current passing through the voltage regulator diode, thereby protecting the voltage regulator diode.

[0018] Preferably, the second voltage detection module is configured as an integrated voltage detector, including a voltage detection chip, wherein a comparator and a reference voltage source are internally disposed in the voltage detection chip.

[0019] By adopting the above technical solution and using an integrated voltage detector, the circuit structure can be simplified and the reliability and stability of the circuit can be improved.

[0020] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The hardware protection circuit monitors the working voltage of the IGBT in real time and can quickly cut off the base current of the IGBT when the voltage is abnormal, thereby effectively protecting the IGBT and preventing it from being damaged by overvoltage or overcurrent, thus improving the reliability and service life of the equipment; 2. The circuit adopts a simple hardware structure and does not rely on complex software algorithms and external monitoring equipment, which reduces system cost and complexity, while improving response speed and meeting the needs of real-time protection; 3. By optimizing the design of the voltage detection module and the control unit, the accuracy and stability of the circuit are further improved, making the protection circuit suitable for various harsh working environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the hardware protection circuit structure of the IGBT in the embodiment of the present application; Markings in the accompanying drawings: 1. Switching device; 2. Control circuit; 21. First voltage detection module; 211. Voltage detection resistor; 212. Operational amplifier acquisition unit; 22. Comparator module; 23. Second voltage detection module; 231. First voltage input terminal; 232. First resistor; 233. First switching tube; 234. Second voltage input terminal; 235. Second resistor; 236. Second switching tube; 237. Zener diode; 238. Current limiting resistor; 239. Voltage divider resistor. DETAILED DESCRIPTION

[0022] The following is combined with Figure 1 The present invention is described in further detail.

[0023] Example 1 The present embodiment discloses a hardware protection circuit for an IGBT, which can effectively cut off the operation of the IGBT to ensure its safety when the voltage or current is abnormal. Specifically, the hardware protection circuit for the IGBT includes a switch device 1 and a control circuit 2. One end of the switch device 1 is directly connected to the base of the IGBT, and the other end is grounded. The control circuit 2 is used to detect the driving voltage of the IGBT, and when the driving voltage of the IGBT is small, the switch device 1 is turned on so that the gate of the IGBT is grounded, and then the IGBT is turned off to achieve protection. Specifically, the switch device 1 uses an NPN-type transistor, whose collector is connected to the gate of the IGBT and the emitter is grounded. Therefore, it is only necessary to control the on and off of the switch device 1 to control the gate voltage of the IGBT, thereby controlling the on and off of the IGBT to achieve protection of the IGBT.

[0024] Further, in the embodiment of the present application, the control circuit 2 includes a first voltage detection module 21, a second voltage detection module 23 and a comparator module 22. The comparator module 22 has a first input terminal, a second input terminal and an output terminal, the first input terminal is connected to the first voltage detection module 21, the second input terminal is connected to the second voltage detection module 23, and the output terminal of the comparator module 22 is connected to the base of the switch device 1, so as to control the on and off of the switch device 1.

[0025] First, the main task of the first voltage detection module 21 is to monitor the working voltage of the IGBT in real time. The module includes a voltage detection resistor 211 and an operational amplifier acquisition unit 212. One end of the voltage detection resistor 211 is connected to the emitter of the IGBT, and the other end is grounded. When the IGBT is working, a voltage signal will be generated at both ends of the voltage detection resistor 211. The input end of the operational amplifier acquisition unit 212 is connected to the voltage detection resistor 211 to receive the voltage signal, convert the voltage signal into a level signal, and output a high level.

[0026] Next, the second voltage detection module 23 is used to continuously monitor the voltage of the IGBT drive power supply. It has a reference voltage and compares the real-time power supply voltage with the reference voltage through the connection with the IGBT drive power supply. When the IGBT drive power supply voltage is maintained above the reference voltage, the module will stably output a high level; once the IGBT drive power supply voltage drops below the reference voltage, it will immediately switch to a low level output.

[0027] Specifically, the second voltage detection module 23 includes a first voltage input terminal 231, a first resistor 232, a first switch tube 233 and a control unit. The first voltage input terminal 231 is connected to a 5V voltage. One end of the first resistor 232 is connected to the first voltage input terminal 231, and the other end is connected to the comparator module 22, thereby providing a high-level signal to the comparator module 22. The first switch tube 233 is connected to one end of the first resistor 232 connected to the comparator module 22. In the embodiment of the present application, the first switch tube 233 adopts an NPN-type triode, whose collector is connected to the first resistor 232 and the emitter is grounded. The second voltage detection module 23 also includes a control unit, and the output end of the control unit is connected to the base of the first switch tube 233, thereby providing a start-up voltage for the first switch tube 233 and controlling the on and off of the first switch tube 233.

[0028] Furthermore, the control unit includes a voltage regulator diode 237, a second voltage input terminal 234, a second switch tube 236, and a second resistor 235. One end of the voltage regulator diode 237 is connected to the driving power supply of the IGBT, and the other end is connected to the second switch tube 236. In the present application, the voltage of the IGBT driving power supply is 15V, and the breakdown voltage of the voltage regulator diode 237 is 10V. Therefore, when the voltage of the IGBT driving power supply is less than 10V, it can be determined that the power supply voltage is too small. At this time, the voltage regulator diode 237 does not work, so the voltage regulator diode 237 can provide a reference voltage of 10V.

[0029] One end of the voltage-stabilizing diode 237 connected to the second switch tube 236 is also connected to a current-limiting resistor 238 , and the current-limiting resistor 238 is grounded to protect the voltage-stabilizing diode 237 .

[0030] The second switch tube 236 is specifically selected as an NPN type transistor, whose base is connected to the voltage stabilizing diode 237, the emitter is grounded, the collector is connected to the second resistor 235, and is also connected to the base of the second switch tube 236 as the output end of the control unit. The second resistor 235 is further connected to the second voltage input terminal 234. The second voltage input terminal 234 is connected to a 5V voltage, thereby providing a turn-on voltage for the first switch tube 233.

[0031] In addition, in the embodiment of the present application, both the first switch tube 233 and the second switch tube 236 can be replaced by MOS tubes.

[0032] The implementation principle of Example 1 is as follows: This embodiment integrates the first voltage detection module 21, the second voltage detection module 23 and the comparator module 22 to construct a set of efficient and fast-responding IGBT hardware protection circuits. Under normal working conditions, this circuit can monitor the operating voltage and power supply voltage of the IGBT in real time to ensure that they operate within a safe range. Once any abnormality is detected, such as a drop or loss of the operating voltage, or instability of the power supply voltage, the circuit will immediately cut off the power supply of the IGBT by controlling the first switch tube 233 of the switch device 1, thereby achieving the purpose of protection.

[0033] The specific implementation method for the technical effect of low voltage protection is as follows: When the IGBT driving power supply voltage is less than 10V, the breakdown voltage of the Zener diode 237 is not reached, so the Zener diode 237 is in a short circuit state, and the base of the second switch tube 236 is at a low level, and since the emitter is grounded, the base-emitter voltage is less than the turn-on voltage of 0.7V, so the second switch tube 236 is in an off state. The base of the first switch tube 233 is connected to the second voltage input terminal 234 through the second resistor 235, and since the emitter of the first switch tube 233 is grounded, the base-emitter voltage of the first switch tube 233 is greater than the turn-on voltage of 0.7V, and the first switch tube 233 is turned on. At this time, the collector of the first switch tube 233 is pulled to the same low level as the emitter, so the second input terminal of the comparator module 22 is also at a low level.

[0034] As for the first input terminal of the comparator module 22, as long as the IGBT is working, the level of the first input terminal must be higher than the low level of the first input terminal. At this time, the output terminal of the comparator module 22 outputs a high level. At this time, the base-emitter voltage of the switching device 1 is greater than the turn-on voltage of 0.7V, and the switching device 1 is turned on. Since the emitter of the switching device 1 is grounded, the collector of the switching device 1 is also at a low level, and then the gate of the IGBT is also at a low level, then the IGBT is turned off to achieve low-voltage protection.

[0035] When the working current of IGBT is too large, it will cause heat. At this time, we also need to turn off the IGBT when the current is too large to play a protective role.

[0036] The specific implementation method of the overcurrent protection technical effect is as follows: When the voltage of the IGBT driving power supply is +15V, it is in normal working state, then the Zener diode 237 works and will stabilize the voltage to 10V, then the pin voltage connecting the Zener diode 237 and the current limiting resistor 238 is 5V, at this time, the base-emitter voltage of the second switch tube 236 is greater than the turn-on voltage of 0.7V, then the second switch tube 236 is in the open state, then the collector of the second switch tube 236 is pulled to the same low level as the emitter, then the base of the first switch tube 233 is also at a low level, the base-emitter voltage of the first switch tube 233 is less than the turn-on voltage of 0.7V, then the first switch tube 233 is in the off state.

[0037] The collector and emitter of the first switch tube 233 are connected in parallel with a voltage-dividing resistor 239, which has the same resistance value as the first resistor 232, and is in series with the first resistor 232. Since the voltage of the first voltage input terminal 231 is 5V, the second input terminal of the comparator module 22 is 2.5V at this time. The first input terminal of the comparator module 22 is connected to the output terminal of the operational amplifier acquisition unit 212. When the current of the IGBT reaches a certain level, the voltage of the first input terminal of the comparator module 22 will be higher than 2.5V of the second input terminal. At this time, the output terminal of the comparator module 22 outputs a high level. At this time, the base-emitter voltage of the switch device 1 is greater than the start voltage of 0.7V, and the switch device 1 is turned on. The collector of the switch device 1 is pulled to the same low level as the emitter. At this time, the gate of the IGBT is also low, and the IGBT is turned off to achieve overcurrent protection.

[0038] In addition, the hardware protection circuit in this embodiment is not only applicable to the protection of IGBTs, but also applicable to the protection of MOS tubes.

[0039] Example 2 Based on the basic architecture and functions of embodiment 1, this embodiment particularly innovates and optimizes the second voltage detection module 23. Compared with the second voltage detection module 23 constructed with discrete components in embodiment 1, this embodiment uses a more integrated integrated voltage detector to achieve the same function.

[0040] This integrated voltage detector not only integrates the comparator and reference voltage source, but also has higher accuracy and stability. This change significantly simplifies the layout and complexity of the circuit, while also reducing overall costs and improving production efficiency. More importantly, the fast response time of the integrated voltage detector ensures that the IGBT can be protected promptly and effectively even under extreme conditions.

[0041] In terms of implementation principle, the integrated voltage detector can compare the IGBT drive power supply voltage with the internal reference voltage in real time through the built-in high-precision comparator. Once the power supply voltage is found to be abnormal, such as lower than the minimum voltage threshold for safe operation, it will immediately trigger the protection mechanism and control the first switch 233 of the switch device 1 to disconnect through the comparator module 22, thereby quickly cutting off the working power supply of the IGBT. This process is automatic and almost instantaneous, effectively avoiding potential damage to the IGBT caused by power supply voltage fluctuations.

[0042] In this application, the model of the integrated voltage detector may be selected such as LM39050, LM2902, etc.

[0043] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A hardware protection circuit for an IGBT, characterized in that: It comprises a switch device (1) and a control circuit (2); one end of the switch device (1) is connected to the base of the IGBT, and the other end is grounded; the control circuit (2) comprises a first voltage detection module (21), a second voltage detection module (23) and a comparator module (22); The first voltage detection module (21) is connected to the IGBT and obtains the IGBT working voltage signal, outputs a high level when the voltage signal is greater than zero, and outputs a low level when the voltage signal is equal to zero; The second voltage detection module (23) has a reference voltage, and the second voltage detection module (23) is connected to the IGBT driving power supply and compares the power supply voltage with the reference voltage; when the power supply voltage is greater than the reference voltage, a high level is output, and when the power supply voltage is lower than the reference voltage, a low level is output; The comparator module (22) has a first input end, a second input end and an output end; the output end of the first voltage detection module (21) is connected to the first input end; the output end of the second voltage detection module (23) is connected to the second input end; the output end of the comparator module (22) is connected to the switch device (1) and is used to control the on and off of the switch device (1).

2. The IGBT hardware protection circuit according to claim 1, characterized in that: The first voltage detection module (21) comprises a voltage detection resistor (211) and an operational amplifier acquisition unit (212); the voltage detection resistor (211) is connected to the emitter of the IGBT to detect the operating voltage of the IGBT; and the operational amplifier acquisition circuit is connected to the voltage detection resistor (211) to obtain a voltage signal.

3. The IGBT hardware protection circuit according to claim 1, characterized in that: The second voltage detection module (23) comprises a first voltage input terminal (231), a first resistor (232) and a first switch tube (233), wherein the first resistor (232) is connected to the first voltage input terminal (231), and the first resistor (232) is connected to the second input terminal; One end of the first switch tube (233) is connected to the first resistor (232), and the other end is grounded; when the first switch tube (233) is turned on, the first resistor (232) is grounded; It also comprises a control unit for controlling the on and off of the first switch tube (233), wherein the reference voltage is arranged in the control unit; the input end of the control unit is connected to the power supply, and the output end is connected to the first switch tube (233).

4. The IGBT hardware protection circuit according to claim 3, characterized in that: The first switch tube (233) is configured as a triode, the base of which is connected to the voltage-stabilizing diode (237), and the emitter and collector of which are respectively connected to the first resistor (232) and the ground.

5. The IGBT hardware protection circuit according to claim 3, characterized in that: The control unit comprises a second voltage input terminal (234), a second resistor (235) and a second switch tube (236); the second resistor (235) is connected to the second voltage input terminal (234); one end of the second switch tube (236) is connected to the second resistor (235), and the other end is grounded; when the second switch tube (236) is turned on, the second resistor (235) is grounded; The control unit further comprises a voltage stabilizing diode (237), the voltage stabilizing diode (237) providing a reference voltage, one end of which is connected to the IGBT driving power supply, and the other end of which is connected to the second switch tube (236).

6. The IGBT hardware protection circuit according to claim 5, characterized in that: The second switch tube (236) is configured as a triode, the base of which is connected to the voltage-stabilizing diode (237), and the emitter and collector of which are respectively connected to the second resistor (235) and the ground.

7. The IGBT hardware protection circuit according to claim 5, characterized in that: One end of the voltage-stabilizing diode (237) connected to the second switch tube (236) is also connected to a current-limiting resistor (238), and the current-limiting resistor (238) is grounded.

8. The IGBT hardware protection circuit according to claim 3, characterized in that: The second voltage detection module (23) is configured as an integrated voltage detector, comprising a voltage detection chip, wherein a comparator and a reference voltage source are provided inside the voltage detection chip.

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