An IGBT working state monitoring circuit

Abstract

The present invention discloses an IGBT working state monitoring circuit, and relates to the field of power semiconductor application technology. The circuit comprises: a switch module, a voltage divider module and a monitoring module; the first end of the switch module is connected to a first input voltage; the second end of the switch module is connected to the collector of the IGBT to be monitored; the third end of the switch module is connected to one end of the voltage divider module; the other end of the voltage divider module is connected to the emitter of the IGBT; the voltage divider connection end of the voltage divider module is connected to the monitoring module; the monitoring module determines the working state of the IGBT to be monitored according to the voltage state of the voltage divider connection end of the voltage divider module. The present invention can monitor the working state of the IGBT in real time.

Description

Technical Field

[0001] The invention relates to the technical field of power semiconductor application, and in particular to an IGBT working state monitoring circuit. Background Art

[0002] The existing general-purpose products receive the control signal of the upper controller through the optical fiber transmitter. Generally, the light represents the IGBT opening instruction; the absence of light represents the IGBT closing instruction. At the same time, when the IGBT controller receives the control signal of the upper controller or the IGBT driver receives the control signal of the upper controller, it immediately feeds back the control signal to inform the upper controller: the IGBT controller or driver has received the control signal. At this time, after receiving the feedback signal, the upper controller believes that the IGBT can work according to the control signal, but the actual working state of the IGBT is not fed back to the upper controller. Therefore, the existing general-purpose products cannot accurately associate the actual working state of the IGBT, and the upper controller cannot accurately know the opening and closing time of the IGBT. Summary of the invention

[0003] The purpose of the present invention is to provide an IGBT working state monitoring circuit, which can monitor the working state of the IGBT in real time.

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

[0005] An IGBT working state monitoring circuit, the monitoring circuit comprising a switch module, a voltage dividing module and a monitoring module;

[0006] The first end of the switch module is connected to the first input voltage; the second end of the switch module is connected to the collector of the IGBT to be monitored; the third end of the switch module is connected to one end of the voltage divider module;

[0007] The other end of the voltage divider module is connected to the emitter of the IGBT to be monitored; the voltage divider connection end of the voltage divider module is connected to the monitoring module;

[0008] In the non-diode freewheeling mode, when the IGBT to be monitored is not turned on, the switch module is not turned on, the voltages of the first end and the second end of the switch module are within a first preset voltage range, the voltage value of the third end of the switch module is 0, and the voltage of the voltage dividing connection end of the voltage dividing module is 0;

[0009] When the IGBT to be monitored is turned on, the switch module is turned on, the voltages of the first terminal and the second terminal of the switch module are within a second preset voltage range, the voltage value of the third terminal of the switch module is within a third preset threshold range, and the voltage of the voltage dividing connection terminal of the voltage dividing module is within a fourth preset threshold range; the minimum values ​​of the third preset threshold range and the fourth preset threshold range are both greater than 0;

[0010] The monitoring module determines the working state of the IGBT to be monitored according to the voltage state of the voltage dividing connection terminal of the voltage dividing module.

[0011] Optionally, the voltage dividing module includes a first voltage dividing resistor and a second voltage dividing resistor;

[0012] One end of the first voltage-dividing resistor is connected to the third end of the switch module; the other end of the first voltage-dividing resistor is connected to one end of the second voltage-dividing resistor; the other end of the second voltage-dividing resistor is connected to the emitter of the IGBT to be monitored;

[0013] A connection point between the first voltage-dividing resistor and the second voltage-dividing resistor is the voltage-dividing connection end.

[0014] Optionally, the switch module includes a transistor, a first resistor, a second resistor, a first diode and a second diode;

[0015] The emitter of the transistor is respectively connected to the first input voltage and one end of the first resistor; the base of the transistor is respectively connected to the other end of the first resistor, one end of the second resistor and the cathode of the first diode; the other end of the second resistor is connected to the anode of the second diode; the cathode of the second diode is connected to the collector of the IGBT to be monitored; the collector of the transistor is respectively connected to one end of the voltage divider module and the anode of the first diode.

[0016] Optionally, the first diode is a Schottky diode.

[0017] Optionally, the second diode includes a plurality of fast recovery diodes.

[0018] Optionally, the monitoring module includes a signal acquisition unit, a third diode and a capacitor;

[0019] The voltage dividing connection end of the voltage dividing module is connected to the positive electrode of the third diode and one end of the capacitor respectively; the negative electrode of the third diode is connected to the second input voltage; the other end of the capacitor is connected to the other end of the voltage dividing module;

[0020] The signal acquisition unit is connected to the voltage division connection end of the voltage division module; the signal acquisition unit is used to acquire the voltage state at the voltage division connection end of the voltage division module.

[0021] Optionally, the signal acquisition unit is a processor.

[0022] Optionally, the signal acquisition unit includes a third resistor, a light emitting device and a first field effect transistor;

[0023] One end of the third resistor is connected to the third input voltage; the other end of the third resistor is connected to one end of the light-emitting device; the other end of the light-emitting device is connected to the drain of the first field effect transistor; the gate of the first field effect transistor is connected to the voltage dividing connection end of the voltage dividing module; the source of the first field effect transistor is connected to the other end of the voltage dividing module.

[0024] Optionally, the signal acquisition unit includes a fourth resistor, a light emitting device and a second field effect transistor;

[0025] One end of the fourth resistor is connected to the fourth input voltage; the other end of the fourth resistor is respectively connected to one end of the light-emitting device and the drain of the second field effect transistor; the other end of the light-emitting device is respectively connected to the other end of the voltage divider module and the source of the second field effect transistor; the gate of the second field effect transistor is connected to the voltage divider connection end of the voltage divider module; the source of the second field effect transistor is connected to the other end of the voltage divider module.

[0026] Optionally, the light-emitting device is an optical coupler or an optical fiber transmitter.

[0027] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0028] In the monitoring circuit provided by the present invention, when the IGBT to be monitored is not turned on, the switch module is not turned on, the voltages at the first and second ends of the switch module are within a first preset voltage range, the voltage value at the third end of the switch module is 0, and the voltage at the voltage-dividing connection end of the voltage-dividing module is 0; when the IGBT to be monitored is turned on, the switch module is turned on, the voltages at the first and second ends of the switch module are within a second preset voltage range, the voltage value at the third end of the switch module is within a third preset threshold range, and the voltage at the voltage-dividing connection end of the voltage-dividing module is within a fourth preset threshold range; the minimum values ​​of the third preset threshold range and the fourth preset threshold range are both greater than 0; the monitoring module determines the working state of the IGBT to be monitored according to the voltage state of the voltage-dividing connection end of the voltage-dividing module, thereby being able to monitor the working state of the IGBT in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 The IGBT working state monitoring circuit provided by the present invention is schematically shown in FIG. Figure 1 ;

[0031] Figure 2 The IGBT working state monitoring circuit provided by the present invention is schematically shown in FIG. Figure 2 ;

[0032] Figure 3 The IGBT working state monitoring circuit provided by the present invention is schematically shown in FIG. Figure 3 .

[0033] Explanation of symbols:

[0034] Switch module—1, voltage divider module—2, monitoring module—3, IGBT to be monitored—4. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The purpose of the present invention is to provide an IGBT working state monitoring circuit, aiming to monitor the working state of the IGBT in real time.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] like Figure 1 As shown, the IGBT working state monitoring circuit in this embodiment includes a switch module, a voltage dividing module and a monitoring module.

[0040] The first end of the switch module is connected to the first input voltage; the second end of the switch module is connected to the collector of the IGBT to be monitored; and the third end of the switch module is connected to one end of the voltage divider module.

[0041] The other end of the voltage divider module is connected to the emitter of the IGBT to be monitored; and the voltage divider connection end of the voltage divider module is connected to the monitoring module.

[0042] In the non-diode freewheeling mode, when the IGBT to be monitored is not turned on, the switch module is not turned on, the voltages at the first end and the second end of the switch module are within a first preset voltage range, the voltage value at the third end of the switch module is 0, and the voltage at the voltage divider connection end of the voltage divider module is 0.

[0043] When the IGBT to be monitored is turned on, the switch module is turned on, the voltages at the first end and the second end of the switch module are within a second preset voltage range, the voltage value at the third end of the switch module is within a third preset threshold range, and the voltage at the voltage divider connection end of the voltage divider module is within a fourth preset threshold range; the minimum values ​​of the third preset threshold range and the fourth preset threshold range are both greater than 0.

[0044] The monitoring module determines the working state of the IGBT to be monitored according to the voltage state of the voltage dividing connection terminal of the voltage dividing module.

[0045] Wherein, the voltage dividing module includes a first voltage dividing resistor and a second voltage dividing resistor.

[0046] One end of the first voltage-dividing resistor is connected to the third end of the switch module; the other end of the first voltage-dividing resistor is connected to one end of the second voltage-dividing resistor; the other end of the second voltage-dividing resistor is connected to the emitter of the IGBT to be monitored.

[0047] A connection point between the first voltage-dividing resistor and the second voltage-dividing resistor is the voltage-dividing connection end.

[0048] As a specific implementation, the switch module includes a transistor, a first resistor, a second resistor, a first diode and a second diode.

[0049] The emitter of the transistor is respectively connected to the first input voltage and one end of the first resistor; the base of the transistor is respectively connected to the other end of the first resistor, one end of the second resistor and the cathode of the first diode; the other end of the second resistor is connected to the anode of the second diode; the cathode of the second diode is connected to the collector of the IGBT to be monitored; the collector of the transistor is respectively connected to one end of the voltage divider module and the anode of the first diode.

[0050] As a specific implementation, the first diode is a Schottky diode. The second diode includes a plurality of fast recovery diodes.

[0051] As a specific implementation, the monitoring module includes a signal acquisition unit, a third diode and a capacitor.

[0052] The voltage dividing connection end of the voltage dividing module is respectively connected to the anode of the third diode and one end of the capacitor; the cathode of the third diode is connected to the second input voltage; and the other end of the capacitor is connected to the other end of the voltage dividing module.

[0053] The signal acquisition unit is connected to the voltage division connection end of the voltage division module; the signal acquisition unit is used to acquire the voltage state at the voltage division connection end of the voltage division module.

[0054] exist Figure 1 , Figure 2 and Figure 3 In the figure, T1 is a PNP transistor, that is, the transistor in the switch module, D1 and D2 are both fast recovery diodes, D1 and D2 are both second diodes, and the second diode includes multiple fast recovery diodes, at least 2; D3 and D4 are both Schottky diodes, D3 is the first diode, D4 ​​is the third diode, R1 is the first resistor, R2 is the second resistor, R3 is the first voltage divider resistor, R4 is the second voltage divider resistor, R1, R2, R3 and R4 are based on actual conditions, such as resistance value, power consumption, packaging, etc., using multiple resistors or series or parallel settings, C1 is a capacitor; C1 filters the divided signal; Vp is an auxiliary power supply, generally >15V. In Figure 1 In the figure, Vc is the controller power supply, that is, the digital power supply. Figure 2 and Figure 3 In the figure, Vc is the digital power supply.

[0055] Specifically, R2 is used to reduce the current passing through in the present invention, and R1 is used to clamp the base voltage of the transistor at the voltage Vp when the IGBT is not conducting. D1 has a unidirectional conduction effect. When the IGBT collector voltage is high, it blocks the high voltage. When the IGBT is conducting, the diode can be forward turned on. D3 is used to speed up the reaction speed of the transistor.

[0056] As a specific implementation, the signal acquisition unit is a processor. That is to say, if the driver unit of the IGBT to be monitored has an MCU or other processors such as DSP / FPGA / CPLD / ARM, Figure 1 As shown, the Vce signal can be given to the processor for unified processing and reported to the upper controller in the form of communication coding or direct signal conversion transmission.

[0057] The working principle of the IGBT working state monitoring circuit of the present invention is:

[0058] When the IGBT is turned on normally, the voltage across C and E will drop below the saturation voltage drop, generally 1 to 3V. If overcurrent occurs, or the IGBT drive circuit is abnormal, and the voltage across CE does not drop, it means that there is an abnormality in the IGBT drive circuit.

[0059] When the IGBT is turned on normally, the base voltage of transistor T1 will decrease, transistors C and E will be turned on, and the voltage divider Vce of resistor R4 will increase. The Vce signal can be directly given to the processor on the drive unit, and the processor transmits it to the upper control unit in other forms. The control unit can know that the IGBT has been turned on normally. The D4 Schottky diode is used to protect against excessive Vce voltage and damage to the hardware. The C1 capacitor is used to improve the anti-interference ability, and the C1 capacitor can be disconnected from the circuit. If an overcurrent occurs, the voltage between the CE of the IGBT increases, then the transistor T1 will be turned off and the Vce voltage will become lower.

[0060] As another specific implementation, the signal acquisition unit includes a third resistor, a light emitting device and a first field effect transistor.

[0061] One end of the third resistor is connected to the third input voltage; the other end of the third resistor is connected to one end of the light-emitting device; the other end of the light-emitting device is connected to the drain of the first field effect transistor; the gate of the first field effect transistor is connected to the voltage dividing connection end of the voltage dividing module; the source of the first field effect transistor is connected to the other end of the voltage dividing module.

[0062] If the drive unit does not have an MCU or other processors such as FPGA / CPLD / DSP / ARM, the Vce signal needs to be isolated and transmitted to other controllers. Figure 2 As shown, T2 is an optical coupler or an optical fiber transmitter, that is, a light-emitting device; R5 is a resistor, that is, a third resistor, used to limit the current of T2; Q1 is an NPN MOSFET, that is, a first field effect tube.

[0063] The working process is: when the Vce voltage is higher than the turn-on voltage of the MOSFET, Q1 is turned on and T2 is turned on and emits light; when the Vce voltage is lower than the turn-on voltage of the MOSFET, Q1 is turned off and T1 does not emit light.

[0064] As a specific implementation, the signal acquisition unit includes a fourth resistor, a light emitting device and a second field effect transistor.

[0065] One end of the fourth resistor is connected to the fourth input voltage; the other end of the fourth resistor is respectively connected to one end of the light-emitting device and the drain of the second field effect transistor; the other end of the light-emitting device is respectively connected to the other end of the voltage divider module and the source of the second field effect transistor; the gate of the second field effect transistor is connected to the voltage divider connection end of the voltage divider module; the source of the second field effect transistor is connected to the other end of the voltage divider module.

[0066] As a specific implementation, the light emitting device is an optical coupler or an optical fiber transmitter.

[0067] like Figure 3 As shown, Figure 2 The optocoupler circuit is modified. Figure 3 Q1 is the second field effect transistor, and R5 is the fourth resistor. When the Vce voltage is higher than the turn-on voltage of the MOSFET, Q1 is turned on and T2 does not emit light; otherwise, T1 is turned on and emits light.

[0068] The present invention can not only detect whether the IGBT is faulty, but also detect the IGBT output voltage. Combined with the DC bus voltage and other information, the actual system output voltage can be inferred. Specifically, based on the information of whether the current IGBT is turned on and the bus voltage, it can be known whether the output voltage is bus positive or bus negative. Combined with the PWM principle, the output voltage can be calculated.

[0069] The present invention overcomes the defect that the traditional IGBT driver only makes feedback according to the control signal from the upper controller and cannot accurately and truly reflect the switching moment of the IGBT.

[0070] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An IGBT working state monitoring circuit, characterized in that: The monitoring circuit includes a switch module, a voltage divider module and a monitoring module; The first end of the switch module is connected to the first input voltage; the second end of the switch module is connected to the collector of the IGBT to be monitored; the third end of the switch module is connected to one end of the voltage divider module; The switch module includes a transistor, a first resistor, a second resistor, a first diode and a second diode; the emitter of the transistor is respectively connected to the first input voltage and one end of the first resistor; the base of the transistor is respectively connected to the other end of the first resistor, one end of the second resistor and the cathode of the first diode; the other end of the second resistor is connected to the anode of the second diode; the cathode of the second diode is connected to the collector of the IGBT to be monitored; the collector of the transistor is respectively connected to one end of the voltage divider module and the anode of the first diode; The other end of the voltage divider module is connected to the emitter of the IGBT to be monitored; the voltage divider connection end of the voltage divider module is connected to the monitoring module; The monitoring module includes a signal acquisition unit, a third diode and a capacitor; the voltage dividing connection end of the voltage dividing module is respectively connected to the positive electrode of the third diode and one end of the capacitor; the negative electrode of the third diode is connected to the second input voltage; the other end of the capacitor is connected to the other end of the voltage dividing module; In the non-diode freewheeling state, when the IGBT to be monitored is not turned on, the switch module is not turned on, the voltages of the first end and the second end of the switch module are within a first preset voltage range, the voltage value of the third end of the switch module is 0, and the voltage of the voltage dividing connection end of the voltage dividing module is 0; When the IGBT to be monitored is turned on, the switch module is turned on, the voltages of the first terminal and the second terminal of the switch module are within a second preset voltage range, the voltage value of the third terminal of the switch module is within a third preset threshold range, and the voltage of the voltage dividing connection terminal of the voltage dividing module is within a fourth preset threshold range; the minimum values ​​of the third preset threshold range and the fourth preset threshold range are both greater than 0; The monitoring module determines the working state of the IGBT to be monitored according to the voltage state of the voltage dividing connection terminal of the voltage dividing module.

2. The IGBT operating status monitoring circuit according to claim 1, characterized in that: The voltage dividing module includes a first voltage dividing resistor and a second voltage dividing resistor; One end of the first voltage-dividing resistor is connected to the third end of the switch module; the other end of the first voltage-dividing resistor is connected to one end of the second voltage-dividing resistor; the other end of the second voltage-dividing resistor is connected to the emitter of the IGBT to be monitored; A connection point between the first voltage-dividing resistor and the second voltage-dividing resistor is the voltage-dividing connection end.

3. The IGBT operating state monitoring circuit according to claim 1, characterized in that: The first diode is a Schottky diode.

4. The IGBT operating state monitoring circuit according to claim 1, characterized in that: The second diode includes a plurality of fast recovery diodes.

5. The IGBT operating state monitoring circuit according to claim 1, characterized in that: The signal acquisition unit is a processor.

6. The IGBT operating state monitoring circuit according to claim 1, characterized in that: The signal acquisition unit includes a third resistor, a light emitting device and a first field effect tube; One end of the third resistor is connected to the third input voltage; the other end of the third resistor is connected to one end of the light-emitting device; the other end of the light-emitting device is connected to the drain of the first field effect transistor; the gate of the first field effect transistor is connected to the voltage dividing connection end of the voltage dividing module; the source of the first field effect transistor is connected to the other end of the voltage dividing module.

7. The IGBT operating state monitoring circuit according to claim 1, characterized in that: The signal acquisition unit includes a fourth resistor, a light emitting device and a second field effect transistor; One end of the fourth resistor is connected to the fourth input voltage; the other end of the fourth resistor is respectively connected to one end of the light-emitting device and the drain of the second field effect transistor; the other end of the light-emitting device is respectively connected to the other end of the voltage divider module and the source of the second field effect transistor; the gate of the second field effect transistor is connected to the voltage divider connection end of the voltage divider module; the source of the second field effect transistor is connected to the other end of the voltage divider module.

8. The IGBT operating status monitoring circuit according to any one of claims 6 to 7, characterized in that: The light emitting device is an optical coupler or an optical fiber transmitter.

Images