A system for detecting terminal contact conditions of an IGBT power device

Abstract

The utility model discloses a kind of IGBT power device terminal contact condition detection systems, belong to power electronics technical field.The system includes controller, sampling circuit, drive circuit and wiring terminal, controller is output first PWM signal to drive circuit after each power on, and the signal of drive circuit output end is collected by sampling circuit to obtain second PWM signal, and then the rising edge time delay of second PWM signal is accumulated and compared with preset value, to judge the contact state of the connection terminal of IGBT power device gate and emitter.The utility model can automatically detect the connection reliability of IGBT terminal when each power on of high-power device, timely find bad contact, open circuit or short circuit and other faults, improve system operation safety and maintenance efficiency, especially suitable for long-term operation and remote operation and maintenance scene of high-voltage high-power power electronics device.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a system for detecting the terminal contact status of IGBT power devices. Background Technology

[0002] In power electronic devices such as high-power frequency converters, inverters, traction systems, and new energy power generation, IGBTs serve as core power switching devices, and their operational reliability directly affects the safe and stable operation of the entire system. IGBTs are typically connected to the drive circuit via terminals to drive and control the gate signal. However, during long-term operation, factors such as vibration, thermal expansion and contraction, and oxidation corrosion can cause faults such as loosening, poor contact, open circuits, or even short circuits at the connection terminals between the IGBT gate and emitter.

[0003] Currently, while most high-power devices undergo rigorous testing before leaving the factory, they lack a mechanism for automatically detecting the IGBT terminal connection status during operation or each startup. Once an abnormal terminal contact occurs, it is often only discovered after the IGBT driver fails or the device is damaged, leading to system shutdown or even more serious safety incidents.

[0004] Therefore, there is an urgent need for a technical solution that can automatically and quickly detect the terminal contact status of IGBT power devices in order to achieve real-time monitoring of connection reliability and improve the intelligence level and operation and maintenance efficiency of the system. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide an IGBT power device terminal contact detection system that can automatically detect the contact status of the IGBT gate and emitter connection terminals every time a high-power device is powered on, and promptly detect abnormalities such as open circuit, short circuit or poor contact, thereby avoiding drive failure or device damage caused by connection failure, and improving the safety and maintainability of the system.

[0006] To achieve the above objectives, this utility model provides an IGBT power device terminal contact detection system, the system comprising a controller, a sampling circuit, a drive circuit, and wiring terminals;

[0007] The controller is connected to the input terminal of the drive circuit; the first output terminal of the drive circuit is connected to the gate of the IGBT power device via the terminal block, and the second output terminal of the drive circuit is connected to the emitter of the IGBT power device via the terminal block; the subsequent stage of the IGBT power device is connected to the high-voltage power circuit.

[0008] The first input terminal of the sampling circuit is connected to the first output terminal of the driving circuit, the second input terminal of the sampling circuit is connected to the second output terminal of the driving circuit, and the output terminal of the sampling circuit is connected to the controller; the sampling circuit is used to extract the voltage difference between the first output terminal and the second output terminal of the driving circuit.

[0009] After each power-on, the controller outputs a first PWM signal to the drive circuit and controls the sampling circuit to collect the signal at the output of the drive circuit to obtain a second PWM signal. Then, the rising edge delay of the sampled second PWM signal for a preset number of cycles is accumulated and compared with the preset rising edge delay. The contact status of the IGBT power device terminals is determined based on the comparison result.

[0010] In the IGBT power device terminal contact detection system of this invention, the controller is a DSP chip with an AD sampling frequency greater than 1M / s.

[0011] In the IGBT power device terminal contact detection system of this invention, the sampling circuit, controller, drive circuit, wiring terminals, and IGBT power device are on the same single board.

[0012] In the IGBT power device terminal contact detection system of this invention, the sampling circuit includes a differential amplifier structure composed of two operational amplifiers, with the second operational amplifier connected as a voltage follower.

[0013] In the IGBT power device terminal contact detection system of this invention, the first input terminal of the sampling circuit is connected to the non-inverting input terminal of the first operational amplifier via a first resistor, and the second input terminal of the sampling circuit is connected to the inverting input terminal of the first operational amplifier via a second resistor; the non-inverting and inverting input terminals of the first operational amplifier are grounded via a third and a fourth resistor, respectively; a fifth resistor is connected between the inverting input terminal and the output terminal of the first operational amplifier; the output terminal of the first operational amplifier is connected to the non-inverting input terminal of the second operational amplifier via a sixth resistor; the inverting input terminal and the output terminal of the second operational amplifier are connected; and the output terminal of the second operational amplifier is connected to the sampling channel of the controller.

[0014] This utility model has the following beneficial effects:

[0015] 1. This utility model automatically performs terminal contact detection every time the system is started, without manual intervention, realizing "detection upon power-on" and effectively preventing operational failures caused by loose connections of IGBT power devices.

[0016] 2. By accumulating the rising edge delay of multiple cycles, noise interference is effectively suppressed, and detection accuracy is improved.

[0017] 3. It can distinguish between different fault modes such as short circuit, open circuit and poor contact, providing clear diagnostic information for maintenance personnel and improving maintenance efficiency.

[0018] 4. By setting reasonable preset delay thresholds and sampling periods, it can be adapted to different types of IGBT devices and connection structures, and has good versatility. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the present invention and constitute a part of this invention, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0020] Figure 1 A schematic diagram of the IGBT power device terminal contact detection system provided in this embodiment of the utility model.

[0021] Figure 2 This is a PWM signal waveform diagram simulating the disconnection of the IGBT power device terminals in an embodiment of this utility model.

[0022] Figure 3 This is a PWM signal waveform diagram simulating a reliable connection of the IGBT power device terminals in an embodiment of this utility model.

[0023] Figure 4 A schematic diagram of the sampling circuit structure of the IGBT power device terminal contact detection system provided in this embodiment of the utility model.

[0024] Figure 5 A schematic diagram of the working process steps of the IGBT power device terminal contact detection system provided in this embodiment of the utility model.

[0025] Figures 6-7 A flowchart illustrating the operation of the IGBT power device terminal contact detection system provided in this embodiment of the utility model. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] The embodiments of this utility model will now be described in further detail with reference to the accompanying drawings. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0028] The present invention is applicable to detecting the contact status of the terminals of IGBT power devices in high-power devices. After the device is powered on, the connection status of the terminals of the IGBT power devices is judged, and abnormal connection of the terminals of the IGBT power devices is detected in time, so as to avoid system failure caused by the failure of IGBT power devices.

[0029] like Figure 1 As shown, this utility model embodiment provides an IGBT power device terminal contact detection system, the system including a controller 1, a sampling circuit 2, a drive circuit 3, and wiring terminals 4;

[0030] The controller 1 is connected to the input terminal of the drive circuit 3; the first output terminal of the drive circuit 3 is connected to the gate of the IGBT power device via the terminal 4, and the second output terminal of the drive circuit 3 is connected to the emitter of the IGBT power device via the terminal 4; the subsequent stage of the IGBT power device is connected to the high-voltage power circuit.

[0031] The first input terminal of the sampling circuit 2 is connected to the first output terminal of the driving circuit 3, the second input terminal of the sampling circuit 2 is connected to the second output terminal of the driving circuit 3, and the output terminal of the sampling circuit 2 is connected to the controller 1; the sampling circuit 3 is used to extract the voltage difference between the first output terminal and the second output terminal of the driving circuit 3.

[0032] After each power-on, the controller 1 outputs a first PWM signal to the drive circuit 3 and controls the sampling circuit 2 to collect the signal at the output of the drive circuit 3 to obtain a second PWM signal. Then, the rising edge delay of the sampled second PWM signal for a preset number of cycles is accumulated and compared with the preset rising edge delay. The contact status of the IGBT power device terminals is determined based on the comparison result.

[0033] This embodiment of the invention determines the terminal contact status based on the accumulated delay value of the sampled PWM signal. The principle is that parasitic capacitance exists within the IGBT power device. If the IGBT power device has good contact, the rising edge of the PWM signal sampled from the drive circuit output will inevitably have a large delay due to the presence of this parasitic capacitance. If the IGBT power device is disconnected, the rising edge delay of the PWM signal sampled from the drive circuit output will be smaller. Figure 2The diagram shows the PWM signal waveform when the terminals of a simulated IGBT power device are disconnected. X1 is the first PWM signal output by the controller, and X2 is the second PWM signal sampled by the DSP. The rising edge delay of the second PWM signal is 64ns. Figure 3 The figure shows the PWM signal waveform when the terminals of the simulated IGBT power device are reliably connected. X1 is the first PWM signal output by the controller, and X2 is the second PWM signal sampled by the DSP. The rising edge delay of the second PWM signal is 161ns. Figure 3 In the process, due to the influence of parasitic capacitance within the IGBT power device, the rise time delay of the second PWM signal is significantly greater than that of the second PWM signal. Figure 2 .

[0034] This utility model's IGBT power device terminal contact detection system integrates a sampling circuit into the existing control circuit and adds testing software to the controller, enabling automatic detection upon power-on. The controller automatically performs terminal contact detection each time the system starts, requiring no manual intervention and achieving "power-on detection," effectively preventing operational failures caused by loose connections. By accumulating multiple rising edge delays, noise interference is effectively suppressed, improving detection accuracy. Combined with a differential sampling circuit design, minute signal delay changes can be accurately captured to identify contact anomalies. By setting reasonable preset delay thresholds and sampling periods, it can adapt to different types of IGBT devices and connection structures, exhibiting good versatility. The detection process injects a low-frequency PWM signal through the existing drive circuit, without affecting the normal operation of the IGBT, ensuring safety and reliability.

[0035] In some embodiments of this invention, the controller 1 is a DSP chip with an AD sampling frequency greater than 1M / s to ensure high-precision delay detection. In a preferred embodiment of this invention, the DSP chip used is a TMS320F28377D, which has high-speed PWM output and AD sampling functions, with an AD sampling frequency greater than 1M / s to ensure accurate capture of rising edge delay.

[0036] In this embodiment of the present invention, the driving circuit 3 includes a dedicated gate driving chip for IGBT power devices, which receives the first PWM signal output by the controller 1 and drives the gate and emitter of the IGBT power devices through the terminal block 4.

[0037] In this embodiment of the present invention, the terminal 4 is used to connect the output terminal of the drive circuit 3 to the gate and emitter pins of the IGBT power device, and is usually a plug-in or screw-type terminal.

[0038] Preferably, in this embodiment of the present invention, the sampling circuit 2 is on the same single board as the controller 1, the drive circuit 3, the terminal block 4, and the IGBT power device, so as to reduce the influence of parasitic parameters and improve the detection consistency.

[0039] like Figure 4 As shown, in a preferred embodiment of this utility model, the sampling circuit 2 includes a differential amplifier structure composed of two operational amplifier stages. The second operational amplifier is connected in the form of a voltage follower. The sampling circuit 2 is used to isolate the low-voltage control circuit and the high-voltage power circuit. Specifically, the first input terminal of the sampling circuit 2 is connected to the non-inverting input terminal of the first operational amplifier U1 via a first resistor R1, and the second input terminal of the sampling circuit 2 is connected to the inverting input terminal of the first operational amplifier U1 via a second resistor R2. The non-inverting and inverting input terminals of the first operational amplifier U1 are grounded through a third resistor R3 and a fourth resistor R4, respectively. A fifth resistor R5 is connected between the inverting input terminal and the output terminal of the first operational amplifier U1, forming an inverting proportional amplifier circuit. The output terminal of the first operational amplifier U1 is connected to the non-inverting input terminal of the second operational amplifier U2 via a sixth resistor R6. The inverting input terminal and the output terminal of the second operational amplifier U2 are connected. The output terminal of the second operational amplifier U2 is connected to the sampling channel of the controller. The resistance values ​​of each resistor are set according to the output voltage value of the driving circuit. In a preferred embodiment of this invention, the resistance values ​​of the first, second, and fifth resistors are all 380kΩ, the resistance values ​​of the third and fourth resistors are 20kΩ, and the resistance value of the sixth resistor is 2kΩ. It is understood that the sampling circuit of this invention is not limited to... Figure 4 The structure shown.

[0040] like Figure 5 , Figure 6 As shown, the workflow of the IGBT power device terminal contact detection system according to this embodiment of the present invention is as follows:

[0041] Step S1: The controller outputs a first PWM signal to the drive circuit after each power-on.

[0042] Step S2: The sampling circuit acquires the signal at the output of the drive circuit and feeds it back to the controller, continuously acquiring P1 cycles to obtain the second PWM signal;

[0043] Step S3: The controller accumulates the rising edge delay of the second PWM signal P1 cycles to obtain the actual sampled accumulated value, and compares it with the preset rising edge delay accumulated value. Based on the comparison result, the terminal contact state is determined.

[0044] P1 is the first preset cycle number.

[0045] like Figure 7 As shown, further, the procedure before step S1 includes:

[0046] While ensuring reliable connection of the IGBT power device terminals, a PWM signal is sent to the input terminal of the drive circuit;

[0047] The signal at the output of the drive circuit is acquired by the sampling circuit and fed back to the controller. P2 cycles are sampled continuously to obtain the standard PWM signal.

[0048] The rising edge delays of P2 cycles of the standard PWM signal are accumulated to obtain a preset rising edge delay accumulation value.

[0049] P2 is the second preset cycle number, and P2 = P1.

[0050] Furthermore, the specific method for determining the terminal contact state based on the comparison results is as follows:

[0051] If the actual sampled accumulated value is greater than or equal to the preset rising edge delay accumulated value, the terminals of the IBGT power device are reliably connected.

[0052] If the actual sampled cumulative value is zero, then there is a short circuit between the gate and emitter of the IGBT power device or a short circuit in the system loop.

[0053] If the actual sampled cumulative value is less than the preset rising edge delay cumulative value, then there is an open circuit between the gate and emitter of the IGBT power device or an open circuit in the system loop.

[0054] Figure 6 , Figure 7 In this context, rise time refers to the time it takes for the PWM signal returned from the sampling circuit to the controller to rise from a low level to a high level. t1 represents the rise time of a single cycle of the PWM waveform when reliably connected, T1 represents the cumulative rise time of multiple cycles of the PWM waveform when reliably connected, t represents the rise time of a single cycle of the PWM sampling signal during actual detection, and T represents the cumulative rise time of multiple cycles of the PWM sampling signal during actual detection.

[0055] The parasitic capacitance of IGBT power devices is stable, therefore the rise time delay of the sampled PWM signal is also relatively stable. If the actual sampled cumulative value is greater than or equal to the preset rise time delay cumulative value, it indicates that the signal transmission is normal and can be determined as a reliable connection; if the actual sampled cumulative value is zero, it indicates that the signal has not generated an effective delay, and it can be determined that there is a short circuit between the gate and emitter of the IGBT power device or a short circuit in the system circuit; if the actual sampled cumulative value is less than the preset rise time delay cumulative value, it indicates that the signal transmission is obstructed and there is poor contact, and it can be determined that there is an open circuit between the gate and emitter of the IGBT power device or an open circuit in the system circuit. The IGBT power device terminal contact detection system of this utility model embodiment can distinguish different fault modes such as short circuit, open circuit and poor contact, providing clear diagnostic information for operation and maintenance personnel and improving maintenance efficiency.

[0056] In this embodiment of the invention, in step S2, the first preset number of cycles is determined based on the parasitic capacitance characteristics of the IGBT power device. Different models of IGBT power devices have different parasitic capacitance values, which have different effects on the rise time delay. In this embodiment of the invention, two IGBT power devices were tested, as detailed in Table 1. Preferably, in this embodiment of the invention, the first preset number of cycles is greater than or equal to 10,000 to improve the accuracy of detection statistics and anti-interference capability.

[0057] Table 1 Comparison of Cumulative Delay for Two IGBT Power Devices

[0058] IGBT power device serial number First PWM signal frequency Number of sampling periods (per second) Rising edge delay accumulation 1 10kHz 10000 7ms 2 10kHz 10000 20ms

[0059] The above are merely specific embodiments of this utility model and should not be construed as limiting the scope of this utility model. Equivalent variations made by those skilled in the art based on this invention, as well as changes known to those skilled in the art, should still fall within the scope of this utility model.

Claims

1. A system for detecting the terminal contact condition of an IGBT power device, characterized in that, The system includes a controller (1), a sampling circuit (2), a drive circuit (3), and a terminal block (4); The controller (1) is connected to the input terminal of the drive circuit (3); the first output terminal of the drive circuit (3) is connected to the gate of the IGBT power device via the terminal block (4); the second output terminal of the drive circuit (3) is connected to the emitter of the IGBT power device via the terminal block (4); the subsequent stage of the IGBT power device is connected to the high-voltage power circuit. The first input terminal of the sampling circuit (2) is connected to the first output terminal of the driving circuit (3), the second input terminal of the sampling circuit (2) is connected to the second output terminal of the driving circuit (3), and the output terminal of the sampling circuit (2) is connected to the controller (1); the sampling circuit (2) is used to extract the voltage difference between the first output terminal and the second output terminal of the driving circuit (3); After each power-on, the controller (1) outputs a first PWM signal to the drive circuit (3) and controls the sampling circuit (2) to collect the signal at the output of the drive circuit (3) to obtain a second PWM signal. Then, the rising edge delay of the sampled second PWM signal with a preset number of cycles is accumulated and compared with the preset rising edge delay. The contact status of the IGBT power device terminals is determined based on the comparison result.

2. The IGBT power device terminal contact detection system according to claim 1, characterized in that, The controller (1) is a DSP chip with an AD sampling frequency greater than 1M / s.

3. The IGBT power device terminal contact detection system according to claim 1, characterized in that, The sampling circuit (2) is on the same board as the controller (1), drive circuit (3), terminal block (4), and IGBT power device.

4. The IGBT power device terminal contact detection system according to claim 1, characterized in that, The sampling circuit (2) includes a differential amplifier structure consisting of two operational amplifiers, with the second operational amplifier connected as a voltage follower.

5. The IGBT power device terminal contact detection system according to claim 4, characterized in that, The first input terminal of the sampling circuit (2) is connected to the non-inverting input terminal of the first operational amplifier (U1) via a first resistor (R1), and the second input terminal of the sampling circuit (2) is connected to the inverting input terminal of the first operational amplifier (U1) via a second resistor (R2). The non-inverting input terminal and the inverting input terminal of the first operational amplifier (U1) are grounded via a third resistor (R3) and a fourth resistor (R4), respectively. A fifth resistor (R5) is connected between the inverting input terminal and the output terminal of the first operational amplifier (U1). The output terminal of the first operational amplifier (U1) is connected to the non-inverting input terminal of the second operational amplifier (U2) via a sixth resistor (R6). The inverting input terminal and the output terminal of the second operational amplifier (U2) are connected. The output terminal of the second operational amplifier (U2) is connected to the sampling channel of the controller.

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