IGBT leakage current detection and current limiting protection circuit based on dynamic feedback regulation

Abstract

The utility model discloses an IGBT leakage current detection and current limiting protection circuit based on dynamic feedback regulation belongs to power electronic device detection technical field, including the current given circuit for setting protection threshold value, the push -pull output circuit for driving current limiting protection pipe, the gear switching circuit for adjusting different current detection gear, the current detection circuit for detecting leakage current in the circuit, the output of current given circuit is connected with the input of push -pull output circuit, the output of push -pull output circuit is electrically connected with current limiting protection pipe, the output of the IGBT pipe of being measured is connected current limiting protection pipe, and the output of current limiting protection pipe is connected current given circuit and gear switching circuit respectively, and the feedback resistance is established between current limiting protection pipe and current given circuit, the output of gear switching circuit is connected current detection circuit, has solved the problem that present technical cannot cope with microsecond breakdown fault, and high pressure is directly used to the operational amplifier and causes the irreversible damage of detection circuit.

Description

Technical Field

[0001] This utility model belongs to the field of power electronic device testing technology, and in particular relates to an IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment. Background Technology

[0002] IGBTs (Insulated Gate Bipolar Transistors) are important power electronic devices primarily used in switching control within power electronic equipment. Due to their importance in high-voltage, high-current applications, their performance needs to be tested and protected, with leakage current detection being a critical performance parameter. Leakage current detection has significant applications in high-voltage short-circuit protection, DC-DC converters, motor control, system power consumption management, and secondary battery current management.

[0003] Existing leakage current detection circuit solutions typically consist of a sampling resistor, a signal amplification circuit, and overcurrent protection components. High-side detection uses a differential amplifier to isolate common-mode voltage, while low-side detection relies on a single-ended amplifier circuit with filtering design. To cope with high-voltage surges, some solutions introduce fuses or transient voltage suppressor diodes (TVS) as protection measures. For example, in the high-side detection circuit, signal conditioning is achieved through a precision resistor network and a high-voltage operational amplifier, and a fuse is used to cut off the circuit during overcurrent; low-side solutions reduce grounding loop inductance through layout optimization and add TVS to absorb voltage spikes. However, the core of these solutions remains at the level of passive detection and simple hardware protection.

[0004] Although existing technologies can monitor basic current, in high-voltage dynamic fault scenarios, the fuse's melting time is mainly determined by the thermal capacity of the fusible material, with a typical response time on the order of 10–100 ms. However, IGBT breakdown faults typically generate destructive currents within microseconds (μs). When the IGBT under test breaks down, the high voltage in the main circuit (e.g., 1200V) directly forms a conductive circuit through the sampling resistor and operational amplifier, far exceeding the device's withstand voltage limit (the input withstand voltage of a conventional operational amplifier is only ±30V), leading to irreversible damage such as the sampling resistor melting and the operational amplifier breaking down. Utility Model Content

[0005] The purpose of this invention is to provide an IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment, so as to solve the technical problem mentioned in the background art that the passive protection scheme adopted by the prior art in IGBT leakage current detection cannot cope with microsecond-level breakdown faults, resulting in high voltage directly acting on the operational amplifier and causing irreversible damage to the detection circuit.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] An IGBT leakage current detection and current limiting protection circuit based on dynamic feedback regulation includes a current setting circuit for setting the protection threshold, a push-pull output circuit for driving the current limiting protection tube, a range switching circuit for adjusting different current detection ranges, and a current detection circuit for detecting leakage current in the circuit.

[0008] The output of the current setting circuit is connected to the input of the push-pull output circuit; the output of the push-pull output circuit is electrically connected to the current limiting protection tube; the output of the IGBT tube under test is connected to the current limiting protection tube, and the output of the current limiting protection tube is connected to the current setting circuit and the gear switching circuit respectively; a feedback resistor is provided between the current limiting protection tube and the current setting circuit; the output of the gear switching circuit is connected to the current detection circuit.

[0009] Preferably, the current-setting circuit includes an operational amplifier.

[0010] Preferably, the non-inverting input of the first operational amplifier is connected to the output of the digital-to-analog converter, and the inverting input of the first operational amplifier is also connected to a feedback resistor.

[0011] Preferably, the push-pull output circuit includes a transistor No. 3, a transistor No. 4, a resistor No. 1, and a resistor No. 2; the transistor No. 3 is an NPN transistor, and the transistor No. 4 is a PNP transistor.

[0012] Preferably, the collector of transistor No. 3 is connected to the collector of transistor No. 4, and is connected to the gate of the current limiting protection transistor through resistor No. 1; the base of transistor No. 3 is connected to the output terminal of the current setting circuit through resistor No. 2, and the base of transistor No. 4 is connected to the collector of transistor No. 3.

[0013] Preferably, the gear switching circuit includes six sets of parallel switch branches, each of which includes a single-pole single-throw switch and a sampling resistor connected in series.

[0014] Preferably, the resistances of the six parallel switch branches are 1MΩ, 100KΩ, 10KΩ, 1KΩ, 100Ω and 10Ω, respectively.

[0015] Preferably, the current detection circuit includes a No. 2 operational amplifier and a No. 10 resistor connected in series.

[0016] Preferably, the non-inverting input of the second operational amplifier is connected to the output of the gear shifting circuit through a resistor of number ten, and the output of the second operational amplifier is connected to the subsequent acquisition circuit.

[0017] Preferably, the current limiting protection tube is model IXTH1N300P3HV-ND.

[0018] Compared with the prior art, the beneficial effects of this utility model are:

[0019] This invention proposes an IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment. It solves the technical problem that the passive protection scheme used in the prior art cannot cope with microsecond-level breakdown faults, resulting in high voltage directly acting on the operational amplifier and causing irreversible damage to the detection circuit. It can also solve the technical problems of slow response speed, insufficient high voltage breakdown protection and limited detection accuracy in IGBT leakage current detection.

[0020] In terms of specific technical implementation, the current setting circuit adopts a closed-loop design with an inverting proportional operational amplifier and a feedback resistor to monitor leakage current in real time and adjust the operating state of the current limiting protection tube, significantly shortening the overcurrent protection response time and avoiding device damage caused by response lag in traditional solutions. Six parallel switching branches with different resistance values ​​are used to adapt to a wide range of detection requirements, from small leakage currents to fault overcurrents, ensuring sensitivity while avoiding signal saturation distortion. The push-pull output circuit uses a symmetrical drive structure with complementary transistors to ensure stable and reliable switching of the current limiting protection tube, effectively resisting interference from current surges on the drive signal. The current detection circuit uses a voltage follower to isolate the sampling signal from the acquisition device, combined with a dual power supply design to suppress noise interference, meeting the signal quality requirements of industrial-grade equipment. Based on general-purpose components, a modular circuit design achieves an integrated solution for detection, protection, and signal processing, significantly reducing hardware complexity and manufacturing costs.

[0021] This invention provides an integrated leakage current detection and protection solution for IGBT devices that features fast response, wide range adaptability, and high reliability, and is suitable for equipment safety protection needs in fields such as industrial power supplies and motor drives. Attached Figure Description

[0022] Figure 1 This is a circuit diagram showing the connection between the preferred embodiment of the present invention and the IGBT tube under test.

[0023] In the diagram: 1. Current setting circuit; 2. Push-pull output circuit; 3. Feedback resistor; 4. Gear switching circuit; 5. Current detection circuit. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0025] The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback regulation includes a current setting circuit 1 for setting the protection threshold, a push-pull output circuit 2 for driving the current limiting protection transistor Q2, a range switching circuit 4 for adjusting different current detection ranges, and a current detection circuit 5 for detecting the leakage current of the IGBT Q1 under test in the circuit. The output terminal of the current setting circuit 1 is connected to the input terminal of the push-pull output circuit 2; the output terminal of the push-pull output circuit 2 is electrically connected to the current limiting protection transistor Q2; the output terminal of the IGBT Q1 under test is connected to the current limiting protection transistor Q2, and the output terminal of the current limiting protection transistor Q2 is connected to both the current setting circuit 1 and the range switching circuit 4; a feedback resistor 3 is provided between the current limiting protection transistor Q2 and the current setting circuit 1; and the output terminal of the range switching circuit 4 is connected to the current detection circuit 5.

[0026] The current setting circuit 1 includes an operational amplifier U1, which is powered by a ±15V dual power supply. The non-inverting input (+) of operational amplifier U1 is connected to the output of the digital-to-analog converter to receive the given voltage signal; the inverting input (-) of operational amplifier U1 is connected to its output, forming an inverting proportional operational circuit; simultaneously, the inverting input of operational amplifier U1 is also connected to a feedback resistor 3 to acquire the current signal of the subsequent stage; the output of operational amplifier U1 is connected to a push-pull output circuit 2 to provide a stable drive signal for the subsequent circuit.

[0027] The push-pull output circuit 2 includes transistor Q3 (number 3), transistor Q4 (number 4), resistor R1 (number 1), and resistor R2 (number 2). Transistor Q3 is an NPN transistor, and transistor Q4 is a PNP transistor. Transistors Q3 and Q4 form a push-pull circuit. The emitter of transistor Q3 is connected to a +15V power supply, and the emitter of transistor Q4 is connected to a -15V power supply. The collector of transistor Q3 is connected to the collector of transistor Q4 and is connected to the gate of the current-limiting protection transistor Q2 through resistor R1. The base of transistor Q3 is connected to the output of the current-setting circuit 1 through resistor R2, and the base of transistor Q4 is directly connected to the collector of transistor Q3. Through the complementary push-pull operation of transistors Q3 and Q4, the gate of the current-limiting protection transistor Q2 is driven and controlled.

[0028] The gear shifting circuit 4 includes six parallel switch branches (SW1 to SW6), each branch including a single-pole single-throw switch and a sampling resistor connected in series. Specifically, one end of switch branches SW1 to SW6 is connected to the input terminal of the circuit, and the other end of each switch is connected to one end of sampling resistors R4 to R9 respectively; the other ends of all sampling resistors are grounded together. By controlling the on / off state of different switches, different sampling resistors can be selected, thereby realizing current measurement of different ranges.

[0029] The current detection circuit 5 includes a second operational amplifier U2 connected in series and a tenth resistor R10. The second operational amplifier U2 is powered by a ±15V dual power supply. The non-inverting input terminal of the second operational amplifier U2 is connected to the output terminal of the gear switching circuit 4 through the tenth resistor R10 to receive the voltage signal selected by the gear switching circuit 4. The inverting input terminal (-) of the second operational amplifier U2 is directly connected to the output terminal of the second operational amplifier U2 to form a voltage follower circuit to avoid impedance interference of the downstream load on the sampling signal. The output terminal of the second operational amplifier U2 is connected to the subsequent acquisition circuit.

[0030] The specific device model in this embodiment is:

[0031] 1. Current limiting protection tube Q2: IXTH1N300P3HV-ND;

[0032] 2. Operational amplifier U1: OPA2192;

[0033] 3. Operational amplifier U2 (number 2): OPA2192

[0034] 4. Transistor Q3: ZXTN2010Z;

[0035] 5. Transistor Q4: ZXTP2012Z.

[0036] The specific parameters of the switching branch of gear shifting circuit 4 are as follows:

[0037] 1. Resistor R4 = 1MΩ, used to measure current from 0 to 1μA;

[0038] 2. Resistor R5 = 100KΩ, used to measure current from 1 to 10μA;

[0039] 3. Resistor R6 = 10KΩ, used to measure current from 10 to 100μA;

[0040] 4. Resistor R7 = 1KΩ, used to measure current from 0.1 to 1mA;

[0041] 5. Resistor R8 = 100Ω, used to measure current from 1 to 10mA;

[0042] 6. Resistor R9 = 10Ω is used to measure current from 0.1 to 100mA.

[0043] The range switching circuit 4 employs a switch branch with progressively increasing resistance values. It uses six sets of resistors (R4 to R9) with different resistance values, in conjunction with switches SW1-SW6, to switch the measurement range. Specifically, the resistance values ​​decrease by a factor of 10 from 1MΩ to 10Ω, corresponding to the following measurement ranges: R4 (1MΩ) for 0–1μA, R5 (100KΩ) for 1–10μA, R6 (10KΩ) for 10–100μA, R7 (1KΩ) for 100μA–1mA, R8 (100Ω) for 1–10mA, and R9 (10Ω) for 10–100mA.

[0044] The gear switching circuit 4 is designed based on Ohm's law (U=IR), employing the principle of "large resistance for small current, small resistance for large current". When measuring a small current, using a larger resistor generates a sufficient voltage signal to ensure measurement accuracy; when measuring a larger current, a smaller resistor is used to avoid excessive voltage drop. The gear switching circuit 4, combined with the current-limiting protection transistor Q2, ensures both measurement accuracy and circuit safety, effectively preventing the detection circuit from burning out if the tested IGBT transistor Q1 fails.

[0045] Working principle:

[0046] When using this circuit, the IGBT Q1 under test must first be correctly connected to the detection circuit, and the drive circuit must be ensured to provide a negative turn-off voltage to the IGBT Q1 to keep it in the off state. To meet the measurement requirements of different ranges, this circuit is equipped with six sets of resistors from R4 to R9. The operator needs to select the appropriate resistance level by manually operating switches SW1 to SW6 according to the estimated leakage current.

[0047] The weak leakage current generated by the tested IGBT Q1 in the off state flows out from the collector, through the drain and source of the current-limiting protection transistor Q2, and then into the gear switching circuit 4. The current flows through a closed switching branch, and Ohm's law is used to generate a sampling voltage proportional to the magnitude of the leakage current across the resistor of that switching branch.

[0048] The sampling voltage is input to the inverting input of operational amplifier U1 via feedback resistor 3, while the reference voltage provided by the digital-to-analog converter is connected to the non-inverting input of operational amplifier U1. Operational amplifier U1 amplifies the voltage difference between the two inputs and outputs it to push-pull output circuit 2, which consists of resistor R2, transistor Q3, transistor Q4, and resistor R1. Push-pull output circuit 2 dynamically adjusts the gate drive voltage of current-limiting protection transistor Q2 according to the control signal: when the leakage current exceeds a preset range, the sampling voltage increases, causing the output of operational amplifier U1 to decrease, the gate voltage of current-limiting protection transistor Q2 to decrease accordingly, and the drain-source on-resistance of current-limiting protection transistor Q2 to increase, thereby limiting the growth of the main circuit current.

[0049] The four-channel range switching circuit matches the leakage current by switching different resistance values. This allows for a higher resistance range to improve measurement sensitivity at low currents, while switching to a lower resistance range to prevent signal saturation at high currents. The voltage signal across resistor R10 is amplified by operational amplifier U2 and output for external devices to collect and record. The entire system achieves accurate leakage current detection and dynamic current limiting protection through a closed-loop feedback mechanism.

[0050] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An IGBT leakage current detection and current limiting protection circuit based on dynamic feedback regulation, comprising a current setting circuit (1) for setting a protection threshold, a push-pull output circuit (2) for driving a current limiting protection transistor, a range switching circuit (4) for adjusting different current detection ranges, and a current detection circuit (5) for detecting leakage current in the circuit; characterized in that: The output terminal of the current setting circuit (1) is connected to the input terminal of the push-pull output circuit (2); the output terminal of the push-pull output circuit (2) is electrically connected to the current limiting protection tube; the output terminal of the IGBT tube under test is connected to the current limiting protection tube, and the output terminal of the current limiting protection tube is connected to the current setting circuit (1) and the gear switching circuit (4) respectively; a feedback resistor (3) is provided between the current limiting protection tube and the current setting circuit (1); the output terminal of the gear switching circuit (4) is connected to the current detection circuit (5).

2. The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment according to claim 1, characterized in that, The current-given circuit (1) includes an operational amplifier.

3. The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment according to claim 2, characterized in that, The non-inverting input of the first operational amplifier is connected to the output of the digital-to-analog converter, and the inverting input of the first operational amplifier is also connected to a feedback resistor (3).

4. The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment according to claim 1, characterized in that, The push-pull output circuit (2) includes transistor No. 3, transistor No. 4, resistor No. 1, and resistor No. 2; transistor No. 3 is an NPN transistor, and transistor No. 4 is a PNP transistor.

5. The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment according to claim 4, characterized in that, The collector of transistor No. 3 is connected to the collector of transistor No. 4, and is connected to the gate of current limiting protection transistor (Q2) through resistor No. 1; the base of transistor No. 3 is connected to the output terminal of current setting circuit (1) through resistor No. 2, and the base of transistor No. 4 is connected to the collector of transistor No.

3.

6. The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment according to claim 1, characterized in that, The gear switching circuit (4) includes six sets of parallel switch branches, each of which includes a single-pole single-throw switch and a sampling resistor connected in series.

7. The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment according to claim 6, characterized in that, The resistances of the six parallel switch branches are 1MΩ, 100KΩ, 10KΩ, 1KΩ, 100Ω and 10Ω, respectively.

8. The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment according to claim 1, characterized in that, The current detection circuit (5) includes a No. 2 operational amplifier and a No. 10 resistor connected in series.

9. The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment according to claim 8, characterized in that, The non-inverting input of the second operational amplifier is connected to the output of the gear switching circuit (4) through a resistor of number 10, and the output of the second operational amplifier is connected to the subsequent acquisition circuit.

10. The IGBT leakage current detection and current limiting protection circuit based on dynamic feedback adjustment according to claim 1, characterized in that, The current limiting protection tube is model IXTH1N300P3HV-ND.

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