An IGBT peak current anti-misdetection circuit and a circuit including the anti-misdetection circuit

Abstract

The present invention relates to an IGBT turn-on instant peak current anti-misdetection circuit and a circuit including the anti-misdetection circuit, which includes a high-pass filter, a first switch driver, a PWM wave generator, a NOR gate and a second switch driver; the output end of the high-pass filter is connected to the control end of the first switch driver, and the input end of the high-pass filter is connected to the PWM drive circuit of the IGBT gate drive; the input end of the first switch driver is connected to the high-level voltage VCC and the first input end of the NOR gate, and the output end is grounded; the PWM wave generator is connected to the second input end of the NOR gate; the output end of the NOR gate is connected to the control end of the second switch driver; the input end of the second switch driver is connected to the high-level voltage VCC and the desaturation detection circuit of the IGBT, and the output end is grounded. The PWM wave generator can adjust the starting moment and duration of the detection shielding, avoid the uncontrolled starting timing of the shielding, and avoid the mismatch between the shielding time and the IGBT operating frequency.

Description

Technical Field

[0001] The present invention relates to the technical field of insulated gate bipolar transistors, and particularly relates to an IGBT peak current anti-mis-detection circuit and a circuit including the anti-mis-detection circuit. Background Art

[0002] IGBT (Insulated Gate Bipolar Transistor), an insulated gate bipolar transistor, is a composite fully controlled voltage-driven power semiconductor device composed of a BJT (bipolar junction transistor) and a MOS (insulated gate field effect transistor), and has the advantages of both the high input impedance of the MOSFET and the low conduction voltage drop of the GTR.

[0003] At the moment when the IGBT is turned on, peak current will be generated due to stray inductance on the power loop, reverse recovery of the diode, etc. This peak current may mis-trigger the desaturation protection of the IGBT, and the existing solutions are as follows:

[0004] (1) Select an IGBT with a better process;

[0005] (2) Reduce the stray inductance on the loop by using a composite busbar instead of a copper busbar, etc.;

[0006] (3) At the moment when the IGBT is turned on, shield the desaturation protection signal for a fixed period of time through a "blanking capacitor".

[0007] However, selecting an IGBT with a better process and reducing the stray inductance will significantly increase the system cost. For the method of shielding the desaturation protection through a "blanking capacitor", its shielding time is a fixed value and cannot be dynamically adjusted. In the case where the IGBT needs to change the carrier frequency and the load, the shielding may fail (the shielding time is too short) or cause a delay in fault protection (the shielding time is too long). Summary of the Invention

[0008] Therefore, it is necessary to provide an IGBT peak current anti-mis-detection circuit and a circuit including the anti-mis-detection circuit to solve the problems of high cost of selecting an IGBT with a better process and reducing stray inductance, and the fixed shielding time of the method of using an "ablation capacitor" to shield the desaturation protection.

[0009] To achieve the above object, the inventor provides a peak current anti-mis-detection circuit for an IGBT at the moment of turning on, including a high-pass filter, a first switch driver, a PWM wave generator, a NOR gate, and a second switch driver;

[0010] The output end of the high-pass filter is connected to the control end of the first switch driver, and the input end of the high-pass filter is connected to the PWM drive circuit of the IGBT gate drive;

[0011] The input terminal of the first switch driver is connected to the high-level voltage VCC and the first input terminal of the NOR gate, and the output terminal is grounded.

[0012] The PWM wave generator is connected to the second input terminal of the NOR gate.

[0013] The output terminal of the NOR gate is connected to the control terminal of the second switch driver.

[0014] The input terminal of the second switch driver is connected to the high-level voltage VCC and the desaturation detection circuit of the IGBT, and the output terminal is grounded.

[0015] Further optimization includes a power amplifier circuit. The input terminal of the power amplifier circuit is connected to the output terminal of the high-pass filter, and the output terminal of the power amplifier circuit is connected to the control terminal of the first switch driver.

[0016] Further optimization, the high-pass filter is an RC high-pass filter.

[0017] Further optimization, both the first switch driver and the second switch driver are MOSFET power tubes.

[0018] Further optimization, the MOSFET power tube is an N-channel MOSFET power tube;

[0019] The control terminals of the first switch driver and the second switch driver are the gates of the N-channel MOSFET power tubes, the input terminals of the first switch driver and the second switch driver are the drains of the N-channel MOSFET power tubes, and the output terminals of the first switch driver and the second switch driver are the sources of the N-channel MOSFET power tubes.

[0020] Another technical solution is also provided: a circuit, including an IGBT, a PWM drive circuit, an IGBT turn-on instant peak current anti-misdetection circuit, and a desaturation detection circuit;

[0021] The gate of the IGBT is connected to the PWM drive circuit;

[0022] The desaturation detection circuit is connected to the collector of the IGBT;

[0023] The IGBT turn-on instant peak current anti-misdetection circuit is the above-mentioned IGBT turn-on instant peak current anti-misdetection circuit.

[0024] Different from the prior art, in the above technical solution, the input end of the high-pass filter is a pulse signal. When the IGBT is turned on instantaneously, there is a rising-edge jump in the gate drive PWM of the IGBT. The high-pass filter outputs a triangular wave signal to the first switch driver to drive the first switch driver. When the signal wave exceeds the conduction threshold of the first switch driver, the input end and the output end of the first switch driver are conducted, and the input end of the first switch driver outputs a low level to the first input end of the NOR gate. The output end of the PWM wave generator is connected to the second input end of the NOR gate, and the duty cycle of the PWM wave generator can be adjusted. By adjusting the triggering timing of the PWM falling edge of the PWM generator, the starting timing of the shielding of the desaturation detection circuit can be controlled, and by adjusting the duty cycle of the PWM generator, the shielding duration of the desaturation detection circuit can be controlled. When any one of the first input end or the second input end of the NOR gate is at a high level, the NOR gate outputs a low level; otherwise, the NOR gate outputs a high level. The level signal output by the NOR gate drives the second switch driver. When the NOR gate outputs a low level, the second switch driver inputs a high level to the desaturation detection circuit, and when the NOR gate outputs a high level, the second switch driver inputs a low level to the desaturation detection circuit. When the level signal of the second switch driver to the desaturation detection circuit is at a low level, the desaturation protection of the IGBT by the desaturation detection circuit is in a shielded state. Compared with the method of selecting IGBTs with better processes and reducing stray inductance, this solution increases the cost less. When the IGBT operates under variable carrier frequency control or variable load conditions, by adjusting the falling edge moment of the PWM wave generator, the starting moment of the detection shielding can be adjusted to avoid the starting timing of the shielding being out of control (too early or too late). When the IGBT operates under variable carrier frequency control or variable load conditions, by adjusting the duty cycle of the PWM waveform generator, the shielding duration can be adjusted to avoid the shielding time not matching the operating frequency of the IGBT (too long or too short). Description of the Drawings

[0025] Figure 1 It is a circuit schematic diagram of a spike current anti-misdetection circuit for the IGBT turn-on instant described in the specific embodiment;

[0026] Figure 2 It is a waveform diagram of each observation point of the spike current anti-misdetection circuit for the IGBT turn-on instant described in the specific embodiment.

[0027] Description of the Reference Numerals:

[0028] 110. First switch driver

[0029] 120. PWM wave generator

[0030] 130. NOR gate

[0031] 140. Second switch driver

[0032] 150. High-pass filter

[0033] 160. Power amplification circuit Detailed implementation mode

[0034] To describe in detail the technical content, structural features, achieved objectives and effects of the technical solution, the following is a detailed description in conjunction with specific embodiments and with reference to the accompanying drawings.

[0035] Please refer to Figure 1-2 , this embodiment provides an IGBT turn-on instant peak current anti-misdetection circuit, including a first switch driver 110, a PWM wave generator 120, a NOR gate 130, a second switch driver 140 and a high-pass filter 105;

[0036] The output end of the high-pass filter 150 is connected to the control end of the first switch driver 110, and the input end of the high-pass filter 150 is connected to the PWM drive circuit of the IGBT gate drive. Among them, the high-pass filter 150 is an RC filter.

[0037] The input end of the first switch driver 110 is connected to the high-level voltage VCC and the first input end of the NOR gate 130, and the output end is grounded;

[0038] The PWM wave generator 120 is connected to the second input end of the NOR gate 130;

[0039] The output end of the NOR gate 130 is connected to the control end of the second switch driver 140;

[0040] The input end of the second switch driver 140 is connected to the high-level voltage VCC and the desaturation detection circuit of the IGBT, and the output end is grounded.

[0041] The input end of the high-pass filter 150 is a pulse signal. When the IGBT is turned on instantaneously, there is a rising-edge jump in the gate drive PWM of the IGBT. The high-pass filter 150 outputs a triangular wave signal to drive the first switch driver 110. When the signal wave exceeds the conduction threshold of the first switch driver 110, the input end and the output end of the first switch driver 110 are conducted, and then the input end of the first switch driver 110 outputs a low level to the first input end of the NOR gate 130. The output end of the PWM wave generator 120 is connected to the second input end of the NOR gate 130. The duty cycle of the PWM wave generator 120 can be adjusted. By adjusting the triggering timing of the PWM falling edge of the PWM generator, the starting timing of the desaturation detection circuit shielding can be controlled. By adjusting the duty cycle of the PWM generator, the shielding duration of the desaturation detection circuit can be controlled. When any one of the first input end or the second input end of the NOR gate 130 is at a high level, the NOR gate 130 outputs a low level; otherwise, the NOR gate 130 outputs a high level. The level signal output by the NOR gate 130 drives the second switch driver 140. When the NOR gate 130 outputs a low level, the second switch driver 140 inputs a high level to the desaturation detection circuit. When the NOR gate 130 outputs a high level, the second switch driver 140 inputs a low level to the desaturation detection circuit. When the level signal output by the second switch driver 140 to the desaturation detection circuit is at a low level, the desaturation protection of the IGBT by the desaturation detection circuit is in a shielding state. Compared with the method of selecting IGBTs with better processes and reducing stray inductance, this solution increases the cost less. When the IGBT operates under variable carrier frequency control or variable load conditions, by adjusting the falling edge moment of the PWM wave generator 120, the starting moment of the detection shielding can be adjusted to avoid the uncontrolled starting timing of the shielding (too early or too late). When the IGBT operates under variable carrier frequency control or variable load conditions, by adjusting the duty cycle of the PWM waveform generator, the shielding duration of the detection can be adjusted to avoid the mismatch between the shielding time and the operating frequency of the IGBT (too long or too short).

[0042] The input end of the high-pass filter 150 is a pulse signal. Only at the rising edge moment of the pulse signal, that is, when the IGBT is in the on instant, the high-pass filter 150 will output a high level signal to drive the first switch driver 110. When the signal at the input end of the high-pass filter 150 becomes a stable level, it means that the IGBT is not in the on instant, and the high-pass filter outputs a low level.

[0043] In this embodiment, a power amplification circuit 160 is further included. The input end of the power amplification circuit 160 is connected to the output end of the high-pass filter, and the output end of the power amplification circuit 160 is connected to the control end of the first switch driver 110.

[0044] In this embodiment, the first switch driver 110 and the second switch driver 140 are both MOSFET power tubes. A MOSFET power tube (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET), a metal-oxide semiconductor field-effect transistor, is simply referred to as a MOSFET. Among them, the MOSFET power tube is an N-channel MOSFET power tube; the control terminals of the first switch driver 110 and the second switch driver 140 are the gates of the N-channel MOSFET power tubes, the input terminals of the first switch driver 110 and the second switch driver 140 are the drains of the N-channel MOSFET power tubes, and the output terminals of the first switch driver 110 and the second switch driver 140 are the sources of the N-channel MOSFET power tubes.

[0045] When the gate of the N-channel MOSFET power tube receives a high-level signal, the drain and source of the N-channel MOSFET power tube conduct. The source of the N-channel MOSFET power tube is grounded, and the drain is connected to a high-level voltage. When the drain and source conduct, the drain of the N-channel MOSFET power tube outputs a low-level signal; when the gate of the N-channel MOSFET power tube receives a low-level signal, the drain and source of the N-channel MOSFET power tube are cut off, and the drain outputs a high-level signal, thereby realizing the opening or closing of the desaturation protection shielding of the desaturation detection circuit.

[0046] In another embodiment, a circuit includes an IGBT, a PWM drive circuit, an IGBT turn-on instant spike current anti-mis-detection circuit, and a desaturation detection circuit;

[0047] The gate of the IGBT is connected to the PWM drive circuit;

[0048] The desaturation detection circuit is connected to the collector of the IGBT;

[0049] The IGBT turn-on instant spike current anti-mis-detection circuit is the IGBT turn-on instant spike current anti-mis-detection circuit described in the above embodiment.

[0050] The input terminal of the high-pass filter 150 is a pulse signal. When the IGBT is turned on instantaneously, there is a rising edge jump in the gate drive PWM of the IGBT. The high-pass filter 150 outputs a triangular wave signal to the first switch driver 110 to drive the first switch driver 110. When the signal wave exceeds the conduction threshold of the first switch driver 110, the input terminal and the output terminal of the first switch driver 110 are conducted, and then the input terminal of the first switch driver 110 outputs a low level to the first input terminal of the NOR gate 130. The output terminal of the PWM wave generator 120 is connected to the second input terminal of the NOR gate 130, and the duty cycle of the PWM wave generator 120 can be adjusted. By adjusting the triggering timing of the PWM falling edge of the PWM generator, the starting timing of the desaturation detection circuit shielding can be controlled, and by adjusting the duty cycle of the PWM generator, the shielding duration of the desaturation detection circuit can be controlled. When any one of the first input terminal or the second input terminal of the NOR gate 130 is at a high level, the NOR gate 130 outputs a low level; otherwise, the NOR gate 130 outputs a high level. The level signal output by the NOR gate 130 drives the second switch driver 140. When the NOR gate 130 outputs a low level, the second switch driver 140 inputs a high level to the desaturation detection circuit, and when the NOR gate 130 outputs a high level, the second switch driver 140 inputs a low level to the desaturation detection circuit. When the level signal from the second switch driver 140 to the desaturation detection circuit is at a low level, the desaturation protection of the IGBT by the desaturation detection circuit is in a shielding state. Compared with the method of selecting IGBTs with better processes and reducing stray inductance, this solution has less cost increase. When the IGBT operates under variable carrier frequency control or variable load conditions, by adjusting the falling edge moment of the PWM wave generator 120, the starting moment of the detection shielding can be adjusted to avoid the starting timing of the shielding being out of control (too early or too late). When the IGBT operates under variable carrier frequency control or variable load conditions, by adjusting the duty cycle of the PWM waveform generator, the shielding duration of the detection can be adjusted to avoid the shielding time not matching the operating frequency of the IGBT (too long or too short).

[0051] It should be noted that although the above embodiments have been described in this article, the patent protection scope of the present invention is not limited thereby. Therefore, based on the innovative concept of the present invention, any changes and modifications made to the embodiments described in this article, or equivalent structural or equivalent process transformations made using the content of the specification and drawings of the present invention, and directly or indirectly applying the above technical solutions to other related technical fields, are all included in the patent protection scope of the present invention.

Claims

1. An anti-misdetection circuit for the peak current at the instant of IGBT turn-on, characterized in that, it includes a high-pass filter, a first switch driver, a PWM wave generator, a NOR gate and a second switch driver; The output end of the high-pass filter is connected to the control end of the first switch driver, and the input end of the high-pass filter is connected to the PWM drive circuit of the IGBT gate drive; The input end of the first switch driver is connected to the high-level voltage VCC and the first input end of the NOR gate, and the output end is grounded; The PWM wave generator is connected to the second input end of the NOR gate; The output end of the NOR gate is connected to the control end of the second switch driver; The input end of the second switch driver is connected to the high-level voltage VCC and the desaturation detection circuit of the IGBT, and the output end is grounded; It further includes a power amplification circuit, the input end of the power amplification circuit is connected to the output end of the high-pass filter, and the output end of the power amplification circuit is connected to the control end of the first switch driver; The high-pass filter is an RC high-pass filter.

2. The anti-misdetection circuit for the peak current at the instant of IGBT turn-on according to claim 1, characterized in that, Both the first switch driver and the second switch driver are MOSFET power tubes.

3. The anti-misdetection circuit for the peak current at the instant of IGBT turn-on according to claim 2, characterized in that, The MOSFET power tube is an N-channel MOSFET power tube; The control ends of the first switch driver and the second switch driver are the gates of the N-channel MOSFET power tubes, the input ends of the first switch driver and the second switch driver are the drains of the N-channel MOSFET power tubes, and the output ends of the first switch driver and the second switch driver are the sources of the N-channel MOSFET power tubes.

4. A circuit, characterized in that, it includes an IGBT, a PWM drive circuit, an anti-misdetection circuit for the peak current at the instant of IGBT turn-on and a desaturation detection circuit; The gate of the IGBT is connected to the PWM drive circuit; The desaturation detection circuit is connected to the collector of the IGBT; The anti-misdetection circuit for the peak current at the instant of IGBT turn-on is the anti-misdetection circuit for the peak current at the instant of IGBT turn-on described in any one of claims 1-3.

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