Igbt active clamp circuit

Abstract

The utility model discloses IGBT active clamping circuit, this circuit includes regulation and control circuit, clamping circuit, push exempt circuit, first diode, IGBT half bridge module, fifth resistance and sixth resistance, regulation and control circuit includes first resistance, second resistance, third resistance and second triode, one end of first resistance connects the negative pole of first diode, and the other end of first resistance connects the base of second triode and one end of second resistance, the emitter of second triode connects one end of third resistance, the collector of second triode connects the first power supply end of push exempt circuit and positive electrode power supply, the other end of second resistance connects the other end of third resistance, and the connecting point connects one end of fifth resistance, one end of sixth resistance and the first gate of IGBT half bridge module, the above-mentioned circuit, utilize the regulation and control circuit of design to realize the amplification of clamping current, realize the amplification of smaller TVS clamping current to larger drive current and act to IGBT gate.

Description

Technical Field

[0001] This utility model relates to the technical field of drive circuits, and in particular to an IGBT active clamping circuit. Background Technology

[0002] For IGBT (Insulated Gate Bipolar Transistor) device drive circuits, the size of the drive resistor directly affects the switching losses, turn-on and turn-off delays, and voltage spikes of the IGBT device. A small drive resistor results in low switching losses but also leads to an excessively high Vce (voltage between the transistor's emitter and collector) spike during turn-off. Traditional TVS (Transient Voltage Suppressor Diode) direct clamping circuits, with a small drive resistor resulting in an excessively high Vce, cause most of the current to return to the negative power supply through the drive resistor, leading to excessively high current in the TVS transistor, excessively high clamping voltage, and unstable unclamping voltage. Simultaneously, the small gate current has limited impact on the equivalent resistance of the collector (C) and emitter (E), or even causes clamping failure. To address the problems of excessive TVS current and power consumption, some existing technologies propose paralleling TVS transistors; however, this approach suffers from cost issues due to multiple parallel or series connections, and still has the problem of an excessively wide clamping voltage range. Therefore, the TVS direct clamping circuit used in IGBT devices in the prior art has the problem of unstable clamping voltage. Utility Model Content

[0003] This utility model provides an active clamping circuit for IGBTs, which aims to solve the problem of unstable clamping voltage in the TVS direct clamping circuit used for IGBT devices in the prior art.

[0004] This utility model embodiment discloses an IGBT active clamping circuit, wherein the IGBT active clamping circuit includes a control circuit, a clamping circuit, a push-off circuit, a first diode, an IGBT half-bridge module, a fifth resistor and a sixth resistor; The control circuit includes a first resistor, a second resistor, a third resistor, and a second transistor; One end of the first resistor is connected to the negative terminal of the first diode, and the other end of the first resistor is connected to the base of the second transistor and one end of the second resistor; the emitter of the second transistor is connected to one end of the third resistor; the collector of the second transistor is connected to the first power supply terminal and the positive power supply of the push-off circuit; the other end of the second resistor is connected to the other end of the third resistor, and the connection point is connected to one end of the fifth resistor, one end of the sixth resistor, and the first gate of the IGBT half-bridge module; The second power supply terminal of the exemption circuit is connected to the negative power supply; the drive control terminal of the exemption circuit is used to input drive signals; the ground terminal of the exemption circuit is connected to the other end of the sixth resistor, the first emitter of the IGBT half-bridge module, and grounded; the connection terminal of the exemption circuit is connected to the other end of the fifth resistor. The first connection terminal of the clamping circuit is connected to the positive terminal of the first diode, and the other connection terminal of the clamping circuit is connected to the first collector of the IGBT half-bridge module.

[0005] The IGBT active clamping circuit mentioned above, wherein the second transistor is an NPN transistor.

[0006] The IGBT active clamping circuit, wherein the push-off circuit includes a fourth resistor, a first transistor, and a third transistor; One end of the fourth resistor serves as the drive control terminal of the exemption circuit, and the other end of the fourth resistor is connected to the base of the first transistor and the base of the third transistor; the emitter of the first transistor is connected to the emitter of the third transistor, and the connection point serves as the connection terminal of the exemption circuit. The collector of the first transistor serves as the first power supply terminal of the exemption circuit, and the collector of the third transistor serves as the second power supply terminal of the exemption circuit.

[0007] The IGBT active clamping circuit, wherein the push-off circuit further includes a first capacitor; One end of the first capacitor is connected to the collector of the first transistor, and the other end serves as the ground terminal of the push-off circuit.

[0008] The IGBT active clamping circuit, wherein the push-off circuit further includes a second capacitor; One end of the second capacitor is connected to the collector of the third transistor, and the other end is connected to the other end of the first capacitor.

[0009] In the aforementioned IGBT active clamping circuit, the first diode is a fast recovery diode.

[0010] The IGBT active clamping circuit, wherein the clamping circuit includes a diode or is composed of multiple diodes connected in series; In the clamping circuit, the positive and negative terminals of the diodes are connected sequentially, and the positive terminal of the diode closest to the first diode is connected to the positive terminal of the first diode.

[0011] The IGBT active clamping circuit includes a second diode, a third diode, and a fourth diode connected in series.

[0012] The IGBT active clamping circuit mentioned above includes diodes that are all transient voltage suppression diodes.

[0013] In the aforementioned IGBT active clamping circuit, the ratio between the second resistor and the third resistor is 3-20.

[0014] This application discloses an IGBT active clamping circuit, which includes a control circuit, a clamping circuit, a push-off circuit, a first diode, an IGBT half-bridge module, a fifth resistor, and a sixth resistor. The control circuit includes a first resistor, a second resistor, a third resistor, and a second transistor. One end of the first resistor is connected to the cathode of the first diode, and the other end of the first resistor is connected to the base of the second transistor and one end of the second resistor. The emitter of the second transistor is connected to one end of the third resistor. The collector of the second transistor is connected to the first power supply terminal and the positive power supply of the push-off circuit. The other end of the second resistor is connected to the other end of the third resistor, and the connection point is connected to one end of the fifth resistor, one end of the sixth resistor, and the first gate of the IGBT half-bridge module. The above circuit utilizes the designed control circuit to amplify the clamping current, enabling a smaller TVS clamping current to be amplified into a larger drive current applied to the IGBT gate, thus improving the stability of the clamping voltage. It resolves the contradiction between Vce and switching losses in traditional TVS clamping circuits and greatly facilitates the adjustment of clamping parameters for different models of IGBTs with the same voltage level. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 The circuit structure diagram of the IGBT active clamping circuit provided in the embodiment of this utility model.

[0017] Reference numerals: S1, Control circuit; S3, Clamping circuit; S2, Push-off circuit; D1, First diode; U1, IGBT half-bridge module; R5, Fifth resistor; R6, Sixth resistor; R1, First resistor; R2, Second resistor; R3, Third resistor; Q2, Second transistor; R4, Fourth resistor; Q1, First transistor; Q3, Third transistor; C1, First capacitor; C2, Second capacitor; D2, Second diode; D3, Third diode; D4, Fourth diode. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0019] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0020] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0021] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] This utility model discloses an IGBT active clamping circuit S3, wherein the IGBT active clamping circuit S3 includes a control circuit S1, a clamping circuit S3, a push-off circuit S2, a first diode D1, an IGBT half-bridge module U1, a fifth resistor R5, and a sixth resistor R6; the control circuit S1 includes a first resistor R1, a second resistor R2, a third resistor R3, and a second transistor Q2; one end of the first resistor R1 is connected to the cathode of the first diode D1, and the other end of the first resistor R1 is connected to the base of the second transistor Q2 and one end of the second resistor R2; the emitter of the second transistor Q2 is connected to one end of the third resistor R3; the collector of the second transistor Q2 is connected to the first power supply terminal and the positive terminal of the push-off circuit S2. Power supply; the other end of the second resistor R2 is connected to the other end of the third resistor R3, and the connection point is connected to one end of the fifth resistor R5, one end of the sixth resistor R6, and the first gate of the IGBT half-bridge module U1; the second power supply terminal of the exemption circuit S2 is connected to the negative power supply, the drive control terminal of the exemption circuit S2 is used to input the drive signal, the ground terminal of the exemption circuit S2 is connected to the other end of the sixth resistor R6, the first emitter of the IGBT half-bridge module U1, and grounded; the connection terminal of the exemption circuit S2 is connected to the other end of the fifth resistor R5; the first connection terminal of the clamping circuit S3 is connected to the positive terminal of the first diode D1, and the other connection terminal of the clamping circuit S3 is connected to the first collector of the IGBT half-bridge module U1.

[0023] The main improvement of this invention lies in the addition of a control circuit S1, composed of a first resistor R1, a second resistor R2, a third resistor R3, and a second transistor Q2, to the existing TVS direct clamping circuit S3. The first resistor R1 limits the current of the TVS transistor in the clamping circuit S3, while the second resistor R2, the third resistor R3, and the second transistor Q2 amplify the TVS transistor current. By adjusting the ratio of the second resistor R2 and the third resistor R3, the total clamping current is adjusted. This counteracts the current pull from the negative power supply and injects a suitable current into the first gate (IGBT gate) of the IGBT half-bridge module U1, thereby adjusting the equivalent resistance Rce between the collector (C) and emitter (E) of the IGBT half-bridge module U1 to enhance the feedback effect and limit Vce spikes.

[0024] Figure 1 The positive power supply voltage is +15V, the negative power supply voltage is -9V, E1 is the ground terminal of the exemption circuit S2, and DRV_G1 is the drive control terminal of the exemption circuit S2. The fifth resistor R5 is the gate drive resistor of the IGBT half-bridge module U1, and the sixth resistor R6 is the gate drive pull-down resistor. The sixth resistor R6 is used to ensure that the drive is in the off state when there is no drive signal. Figure 1In the IGBT half-bridge module U1, Vce is the voltage between its collector and emitter.

[0025] In a more specific embodiment, the second transistor Q2 is an NPN transistor. The ratio between the second resistor R2 and the third resistor R3 is 3-20.

[0026] To improve the application effect of the above circuit, the second transistor Q2 can be set to an NPN transistor. To achieve the corresponding current control function, the ratio between the second resistor R2 and the third resistor R3 can be set to 3-20; in a preferred embodiment, the ratio between the second resistor R2 and the third resistor R3 can be set to 8-12.

[0027] In a more specific embodiment, the exemption circuit S2 includes a fourth resistor R4, a first transistor Q1, and a third transistor Q3. One end of the fourth resistor R4 serves as the drive control terminal of the exemption circuit S2, and the other end of the fourth resistor R4 is connected to the base of the first transistor Q1 and the base of the third transistor Q3. The emitter of the first transistor Q1 is connected to the emitter of the third transistor Q3, and the connection point serves as the connection terminal of the exemption circuit S2. The collector of the first transistor Q1 serves as the first power supply terminal of the exemption circuit S2, and the collector of the third transistor Q3 serves as the second power supply terminal of the exemption circuit S2. Specifically, the exemption circuit S2 also includes a first capacitor C1. One end of the first capacitor C1 is connected to the collector of the first transistor Q1, and the other end serves as the ground terminal of the exemption circuit S2. The exemption circuit S2 also includes a second capacitor C2. One end of the second capacitor C2 is connected to the collector of the third transistor Q3, and the other end is connected to the other end of the first capacitor C1.

[0028] The first transistor Q1 and the third transistor Q3 are the main components of the push-pull circuit, and the fourth resistor R4 is the driving resistor of the push-pull circuit; the first capacitor C1 is the capacitor connected in series between the positive power supply and the ground terminal, and the second capacitor C2 is the capacitor connected in series between the negative capacitor and the ground terminal. The two capacitors are used to provide a large instantaneous driving current.

[0029] In a more specific embodiment, the first diode D1 is a fast recovery diode. Specifically, the clamping circuit S3 includes one diode or is composed of multiple diodes connected in series; the positive and negative terminals of the diodes in the clamping circuit S3 are connected sequentially, and the positive terminal of the diode closest to the first diode D1 is connected to the positive terminal of the first diode D1. The clamping circuit S3 includes a second diode D2, a third diode D3, and a fourth diode D4 connected in series. Further, all diodes included in the clamping circuit S3 are transient voltage suppression diodes.

[0030] The first diode D1 is a fast recovery diode. Its function is to prevent the gate voltage from being injected into the collector (C) when the IGBT half-bridge module U1 is in the on state. During the turn-off process, the excessively high Vce provides a path for the TVS current when the clamping circuit S3 is turned on. The clamping circuit S3 can be composed of one or more diodes. All the diodes included in the clamping circuit S3 are transient voltage suppressor diodes (TVS diodes), which are used to clamp the Vce spike.

[0031] by Figure 1 Taking the circuit structure shown as an example, the working principle of the above IGBT active clamp circuit S3 is described as follows: When the drive control terminal DRV_G1 is high, the first transistor Q1 is turned on, and the high level injects current into the gate through the fifth resistor R5, causing the IGBT half-bridge module U1 to turn on. Finally, the first gate of the IGBT half-bridge module U1 ( Figure 1The voltage at terminal G1 is approximately +15V. When the drive control terminal DRV_G1 is low, the third transistor Q3 is turned on. The low level draws current from the gate through the fifth resistor R5, causing the IGBT half-bridge module U1 to turn off. When Vce is not high during the turn-off process, the diodes in the clamping circuit S3 do not operate. The diodes in the clamping circuit S3 are all high-resistance, and the current is negligible. There is no current in the first resistor R1 and the second resistor R2, and the second transistor Q2 does not conduct. When Vce is too high during the turn-off process, exceeding the operating voltage Vbr (the breakdown voltage of the TVS diode) of the diodes in the clamping circuit S3, the diodes in the clamping circuit S3 quickly respond from high resistance to low resistance and conduct, and the current flowing through the TVS diode is measured as I1. The portion of current I1 flowing through the second resistor R2 is recorded as I2. The other portion of current I1 flows through the base of the second transistor Q2. Considering that the second transistor Q2 is operating in the amplification region, the current flowing through its base is very small and is not considered for now. Assume the forward voltage drop between the base (B) and emitter (E) of transistor Q2 is 0.7V. When I2 × R2 > 0.7V, transistor Q2 conducts, and the current flowing through the third resistor R3 is denoted as I3. According to Kirchhoff's Voltage Law, I2 × R2 = 0.7 + I3 × R3, which further transforms to I3 = (R2 × I2) / R3 - 0.7 / R3. It can be seen that I3 can be adjusted by adjusting R2 / R3, and the total clamping current is I2 + I3. If the 0.7V voltage drop between the base (B) and emitter (E) of transistor Q2 is ignored, then I3 ≈ (R2 × I2) / R3. If R2 / R3 = 10, then I3 = 10 × I2. Therefore, we can conclude that the second transistor Q2 provides 10 times the current of the TVS diode, which is equivalent to 10 TVS diodes connected in parallel. Let the total clamping current be I, then I = I2 + I3. Assuming that when Vce is too high and causes the TVS diode to operate, the gate voltage is V, then the clamping circuit S3 needs to provide a current of (V+9) / R5 to the negative power supply, i.e., -9V. The remaining current flows into the gate of the IGBT half-bridge module U1 to reduce Rce, thereby reducing Vce. After Vce decreases, the currents flowing through the TVS diode I1 decrease, I2 decrease, I3 decrease, and finally the clamping is released, and the gate of the IGBT half-bridge module U1 remains in the off state. It can be seen that when the fifth resistor R5 is relatively small, the current demand of the fifth resistor R5 is very large. The traditional TVS direct clamping circuit S3 will have the problem of excessive clamping voltage. The clamping voltage Vc = Vbr + I × req, where req is the dynamic resistance of the TVS diode when it is turned on. When I is too large, clamping failure may even occur. By using this invention, the current required for clamping can be controlled and Vce can be effectively limited by setting the ratio of the second resistor R2 to the third resistor R3 within a reasonable range.The present invention can decouple the driving parameters and clamping parameters of different IGBT half-bridge modules U1, making the driver board more adaptable and saving costs.

[0032] In practical applications, this circuit can meet the requirements of different types of products, improving product reliability. Because of the functionality of this invention, the selection of the drive resistor is more independent, switching losses are further reduced, Vce clamping is more effective, and the performance of the IGBT half-bridge module is fully utilized. Furthermore, for IGBT half-bridge modules of the same voltage level, the adjustment of drive parameters and clamping parameters is relatively independent and more convenient in practical applications, enhancing the applicability of the driver board and saving production costs.

[0033] This utility model discloses an IGBT active clamping circuit, which includes a control circuit, a clamping circuit, a push-off circuit, a first diode, an IGBT half-bridge module, a fifth resistor, and a sixth resistor. The control circuit includes a first resistor, a second resistor, a third resistor, and a second transistor. One end of the first resistor is connected to the cathode of the first diode, and the other end of the first resistor is connected to the base of the second transistor and one end of the second resistor. The emitter of the second transistor is connected to one end of the third resistor. The collector of the second transistor is connected to the first power supply terminal and the positive power supply of the push-off circuit. The other end of the second resistor is connected to the other end of the third resistor, and the connection point is connected to one end of the fifth resistor, one end of the sixth resistor, and the first gate of the IGBT half-bridge module. The above circuit utilizes the designed control circuit to amplify the clamping current, enabling a smaller TVS clamping current to be amplified into a larger drive current applied to the IGBT gate, thus improving the stability of the clamping voltage. It resolves the contradiction between Vce and switching losses in traditional TVS clamping circuits and greatly facilitates the adjustment of clamping parameters for different models of IGBTs with the same voltage rating.

[0034] The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. An IGBT active clamping circuit, characterized in that, The IGBT active clamping circuit includes a control circuit, a clamping circuit, a push-off circuit, a first diode, an IGBT half-bridge module, a fifth resistor, and a sixth resistor. The control circuit includes a first resistor, a second resistor, a third resistor, and a second transistor; One end of the first resistor is connected to the negative terminal of the first diode, and the other end of the first resistor is connected to the base of the second transistor and one end of the second resistor; the emitter of the second transistor is connected to one end of the third resistor; the collector of the second transistor is connected to the first power supply terminal and the positive power supply of the push-off circuit; the other end of the second resistor is connected to the other end of the third resistor, and the connection point is connected to one end of the fifth resistor, one end of the sixth resistor, and the first gate of the IGBT half-bridge module; The second power supply terminal of the exemption circuit is connected to the negative power supply; the drive control terminal of the exemption circuit is used to input drive signals; the ground terminal of the exemption circuit is connected to the other end of the sixth resistor, the first emitter of the IGBT half-bridge module, and grounded; the connection terminal of the exemption circuit is connected to the other end of the fifth resistor. The first connection terminal of the clamping circuit is connected to the positive terminal of the first diode, and the other connection terminal of the clamping circuit is connected to the first collector of the IGBT half-bridge module.

2. The IGBT active clamping circuit according to claim 1, characterized in that, The second transistor is an NPN transistor.

3. The IGBT active clamping circuit according to claim 2, characterized in that, The exemption circuit includes a fourth resistor, a first transistor, and a third transistor; One end of the fourth resistor serves as the drive control terminal of the exemption circuit, and the other end of the fourth resistor is connected to the base of the first transistor and the base of the third transistor; the emitter of the first transistor is connected to the emitter of the third transistor, and the connection point serves as the connection terminal of the exemption circuit. The collector of the first transistor serves as the first power supply terminal of the exemption circuit, and the collector of the third transistor serves as the second power supply terminal of the exemption circuit.

4. The IGBT active clamping circuit according to claim 3, characterized in that, The exemption circuit also includes a first capacitor; One end of the first capacitor is connected to the collector of the first transistor, and the other end serves as the ground terminal of the push-off circuit.

5. The IGBT active clamping circuit according to claim 4, characterized in that, The exemption circuit also includes a second capacitor; One end of the second capacitor is connected to the collector of the third transistor, and the other end is connected to the other end of the first capacitor.

6. The IGBT active clamping circuit according to any one of claims 1-5, characterized in that, The first diode is a fast recovery diode.

7. The IGBT active clamping circuit according to claim 6, characterized in that, The clamping circuit includes a diode or is composed of multiple diodes connected in series. In the clamping circuit, the positive and negative terminals of the diodes are connected sequentially, and the positive terminal of the diode closest to the first diode is connected to the positive terminal of the first diode.

8. The IGBT active clamping circuit according to claim 7, characterized in that, The clamping circuit includes a second diode, a third diode, and a fourth diode connected in series.

9. The IGBT active clamping circuit according to claim 8, characterized in that, The clamping circuit contains diodes that are all transient voltage suppressor diodes.

10. The IGBT active clamping circuit according to claim 9, characterized in that, The ratio between the second resistor and the third resistor is 3-20.

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