CN-114441917-B - IGBT short circuit detection and protection circuit and short circuit detection and protection method thereof

CN114441917BCN 114441917 BCN114441917 BCN 114441917BCN-114441917-B

Abstract

The application provides an IGBT short circuit detection and protection circuit and a short circuit detection and protection method thereof. The IGBT short circuit detection circuit comprises a sampling circuit, a comparison circuit and a timing circuit, wherein the timing circuit is connected to the comparison circuit, the comparison circuit is connected to the sampling circuit, the sampling circuit is used for connecting stray inductances between an auxiliary emitter and a power emitter in an IGBT to be detected, the sampling circuit is used for collecting voltages of the stray inductances, the comparison circuit is used for comparing the voltages of the stray inductances with preset reference voltages and outputting first signals according to comparison results, the timing circuit is used for outputting second signals indicating whether the IGBT to be detected is in a short circuit or not according to the duration that the first signals are in a preset level state, and the duration that the first signals are in the preset level state is the duration of rising edges of currents flowing through the stray inductances. The application improves the response speed of the IGBT in short circuit detection, thereby reducing the damage risk of the IGBT in short circuit and improving the safety of the IGBT.

Inventors

Chuan Junyin
WU XIAOGUANG
HUANG HUI
WANG ZHIHAN

Assignees

深圳青铜剑技术有限公司

Dates

Publication Date: 20260508
Application Date: 20211231

Claims (7)

1. The IGBT short circuit detection circuit is characterized by comprising a sampling circuit, a comparison circuit and a timing circuit, wherein the timing circuit is connected with the comparison circuit, the comparison circuit is connected with the sampling circuit, the sampling circuit is used for connecting stray inductance between an auxiliary emitter and a power emitter in an IGBT to be detected, the sampling circuit comprises a voltage division branch circuit, the comparison circuit comprises a first comparison branch circuit and a second comparison branch circuit, and the timing circuit comprises a first timing branch circuit, a second timing branch circuit and an OR gate; the sampling circuit is used for collecting the voltage of the stray inductor; the comparison circuit is used for comparing the voltage of the stray inductor with a preset reference voltage and outputting a first signal according to a comparison result; The timing circuit is used for outputting a second signal indicating whether the IGBT to be tested is short-circuited or not according to the duration of the first signal in a preset level state, wherein the duration of the first signal in the preset level state is the duration of the rising edge of the current flowing through the stray inductor; the voltage dividing branch circuit is used for collecting first voltage of the stray inductor, dividing the first voltage to obtain second voltage, and outputting the second voltage to the comparison circuit; the first comparison branch circuit is used for comparing the second voltage with a preset first reference voltage and outputting a first sub-signal to the timing circuit according to a comparison result; the second comparison branch circuit is used for comparing the second voltage with a preset second reference voltage and outputting a second sub-signal to the timing circuit according to a comparison result; Wherein the first reference voltage and the second reference voltage have the following relationship: Wherein Vref1 is the voltage value of the first reference voltage, and Vref2 is the voltage value of the second reference voltage; the first timing branch is used for outputting an increased third voltage to the or gate when the first sub-signal is in the preset level state, and outputting a decreased third voltage to the or gate when the first sub-signal is in other level states; the second timing branch is used for outputting a raised fourth voltage to the or gate when the second sub-signal is in the preset level state, and outputting a lowered fourth voltage to the or gate when the second sub-signal is in other level states; The or gate is configured to output the second signal indicating that the IGBT to be tested is shorted when a sum of the third voltage and the fourth voltage is greater than or equal to a flip threshold voltage of the or gate, and output the second signal indicating that the IGBT to be tested is not shorted when the sum of the third voltage and the fourth voltage is less than the flip threshold voltage of the or gate; The sum of the third voltage and the fourth voltage is greater than or equal to the inversion threshold voltage of the OR gate when the total time length of the first sub-signal and the second sub-signal in the preset level state is greater than or equal to the preset time length, and the sum of the third voltage and the fourth voltage is less than the inversion threshold voltage of the OR gate when the total time length of the first sub-signal and the second sub-signal in the preset level state is less than the preset time length, wherein the total time length of the first sub-signal and the second sub-signal in the preset level state is the duration of the rising edge of the current flowing through the stray inductor.
2. The IGBT short circuit detection circuit of claim 1, wherein the voltage dividing branch circuit comprises a first diode, a second diode, a first resistor and a second resistor, wherein a cathode of the first diode and one end of the first resistor are used for being connected with a first power supply, one end of the second resistor, the other end of the first resistor and an anode of the first diode are respectively connected with the cathode of the second diode, the anode of the second diode is grounded, and the other end of the second resistor is used for being connected with one end of the stray inductance; The voltage dividing branch circuit is specifically configured to collect the first voltage, divide the first voltage by using the first resistor and the second resistor to obtain the second voltage, and output the second voltage to the comparison circuit through a common connection point between the first diode and the second diode, where the second voltage is represented by the following formula: wherein V2 is the voltage value of the second voltage, V1 is the voltage value of the first voltage, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, and VCC is the voltage value of the first power supply.
3. The IGBT short circuit detection circuit of claim 2, wherein the first comparison branch comprises a first comparator and a first pull-up resistor, the second comparison branch comprises a second comparator and a second pull-up resistor, the non-inverting input ends of the first comparator and the second comparator are respectively connected to a common connection point between the first diode and the second diode, the inverting input end of the first comparator is connected to the first reference voltage, the inverting input end of the second comparator is connected to the second reference voltage, the first output end of the first comparator is used for being connected to the first power supply, the second output end of the first comparator is grounded, the third output end of the first comparator and one end of the first pull-up resistor are respectively connected to the timing circuit, the other end of the first pull-up resistor is used for being connected to a second power supply, and the output end of the second comparator and one end of the second pull-up resistor are respectively connected to the second power supply; The first comparison branch circuit is specifically configured to compare the second voltage with the first reference voltage through the first comparator, and output the first sub-signal to the timing circuit through the third output terminal according to a comparison result, where the first sub-signal keeps a high level when the second voltage is greater than the first reference voltage, and changes from a high level to a low level when the second voltage is less than the first reference voltage; The second comparing branch circuit is specifically configured to compare the second voltage with the second reference voltage through the second comparator, and output the second sub-signal to the timing circuit according to a comparison result, where the second sub-signal keeps a high level when the second voltage is greater than the second reference voltage, and changes from a high level to a low level when the second voltage is less than the second reference voltage.
4. The IGBT short circuit detection circuit of claim 3, wherein the first timing branch comprises a first NOT gate, a third diode, a third resistor and a first capacitor, wherein a first input end of the OR gate, one end of the first capacitor and an anode of the third diode are respectively connected with one end of the third resistor, the other end of the first capacitor is grounded, the other end of the third resistor and a cathode of the third diode are respectively connected with an output end of the first NOT gate, and an input end of the first NOT gate is connected with a third output end of the first comparator; The second timing branch circuit comprises a second NOT gate, a fourth diode, a fourth resistor and a second capacitor, wherein a second input end of the OR gate, one end of the second capacitor and an anode of the fourth diode are respectively connected with one end of the fourth resistor, the other end of the second capacitor is grounded, the other end of the fourth resistor and a cathode of the fourth diode are respectively connected with an output end of the second NOT gate, and an input end of the second NOT gate is connected with an output end of the second comparator; The first timing branch circuit is specifically configured to charge the first capacitor through the third resistor to raise the terminal voltage of the first capacitor when the first sub-signal changes from high level to low level and the output of the first not gate changes from low level to high level, and discharge the first capacitor through the third diode to lower the terminal voltage of the first capacitor when the first sub-signal changes from low level to high level and the output of the first not gate changes from high level to low level; The second timing branch is specifically configured to charge the second capacitor through the fourth resistor to raise the terminal voltage of the second capacitor when the second sub-signal changes from high to low and the output of the second not gate changes from low to high, and discharge the second capacitor through the fourth diode to lower the terminal voltage of the second capacitor when the second sub-signal changes from low to high and the output of the second not gate changes from high to low; the or gate is specifically configured to output the second signal that keeps a low level and indicates that the IGBT to be tested does not have a short circuit when a total duration of the first sub-signal and the second sub-signal at a low level is less than the preset duration and a sum of the third voltage and the fourth voltage is less than a flip threshold voltage of the or gate, and output the second signal that changes from a low level to a high level and indicates that the IGBT to be tested has a short circuit when the total duration of the first sub-signal and the second sub-signal at a low level is greater than or equal to the preset duration and the sum of the third voltage and the fourth voltage is greater than or equal to the flip threshold voltage of the or gate.
5. The IGBT short circuit detection method is applied to an IGBT short circuit detection circuit and is characterized by comprising a sampling circuit, a comparison circuit and a timing circuit, wherein the timing circuit is connected with the comparison circuit, the comparison circuit is connected with the sampling circuit, the sampling circuit is used for connecting stray inductance between an auxiliary emitter and a power emitter in an IGBT to be detected, the sampling circuit comprises a voltage division branch, the comparison circuit comprises a first comparison branch and a second comparison branch, and the timing circuit comprises a first timing branch, a second timing branch and an OR gate; The IGBT short circuit detection method comprises the following steps: The voltage dividing branch circuit is used for collecting first voltage of the stray inductor, dividing the first voltage to obtain second voltage and outputting the second voltage to the comparison circuit, wherein the comparison circuit comprises a first comparison branch circuit and a second comparison branch circuit; the first comparison branch circuit compares the second voltage with a preset first reference voltage and outputs a first sub-signal to the timing circuit according to a comparison result; the second comparison branch circuit compares the second voltage with a preset second reference voltage and outputs a second sub-signal to the timing circuit according to a comparison result; Wherein the first reference voltage and the second reference voltage have the following relationship: Wherein Vref1 is the voltage value of the first reference voltage, and Vref2 is the voltage value of the second reference voltage; the first timing branch circuit outputs a third voltage which is increased to the OR gate when the first sub-signal is in a preset level state, and outputs a third voltage which is decreased to the OR gate when the first sub-signal is in other level states; The second timing branch outputs a fourth voltage which is increased to the OR gate when the second sub-signal is in the preset level state, and outputs a fourth voltage which is decreased to the OR gate when the second sub-signal is in other level states; The OR gate outputs a second signal indicating that the IGBT to be tested is short-circuited when the sum of the third voltage and the fourth voltage is greater than or equal to the inversion threshold voltage of the OR gate, and outputs the second signal indicating that the IGBT to be tested is not short-circuited when the sum of the third voltage and the fourth voltage is less than the inversion threshold voltage of the OR gate; The sum of the third voltage and the fourth voltage is greater than or equal to the inversion threshold voltage of the OR gate when the total time length of the first sub-signal and the second sub-signal in the preset level state is greater than or equal to the preset time length, and the sum of the third voltage and the fourth voltage is less than the inversion threshold voltage of the OR gate when the total time length of the first sub-signal and the second sub-signal in the preset level state is less than the preset time length, wherein the total time length of the first sub-signal and the second sub-signal in the preset level state is the duration of the rising edge of the current flowing through the stray inductor.
6. An IGBT short-circuit protection circuit is characterized by comprising a control circuit and an IGBT short-circuit detection circuit according to any one of claims 1-4, wherein the timing circuit is connected to the control circuit, and the control circuit is used for connecting the IGBT to be detected; The control circuit is used for switching on the IGBT to be tested or switching off the IGBT to be tested according to the second signal.
7. The IGBT short-circuit protection method is applied to an IGBT short-circuit protection circuit and is characterized in that the IGBT short-circuit protection circuit comprises a control circuit and the IGBT short-circuit detection circuit according to any one of claims 1-4, wherein the timing circuit is connected to the control circuit, and the control circuit is used for connecting the IGBT to be detected; The IGBT short-circuit protection method comprises the following steps: The sampling circuit collects the voltage of the stray inductor; The comparison circuit compares the voltage of the stray inductor with a preset reference voltage and outputs a first signal according to a comparison result; The timing circuit outputs a second signal indicating whether the IGBT to be detected is short-circuited or not according to the duration of the first signal in a preset level state, wherein the duration of the first signal in the preset level state is the duration of the rising edge of the current flowing through the stray inductor; And the control circuit turns on the IGBT to be tested or turns off the IGBT to be tested according to the second signal.

Description

IGBT short circuit detection and protection circuit and short circuit detection and protection method thereof [ Field of technology ] The application relates to the technical field of power electronic devices, in particular to an IGBT short circuit detection and protection circuit and a short circuit detection and protection method thereof. [ Background Art ] The IGBT (Insulated Gate Bipolar Transistor ) is a composite fully-controlled voltage-driven power semiconductor device composed of a BJT (Bipolar Junction Transistor ) and a MOSFET (Metal-Oxide-Semicondu ctor Field-Effect Transistor, metal-Oxide-semiconductor field effect transistor), which combines the advantages of the above two devices, namely, has a smaller driving power and a lower saturation voltage drop, so that it is very suitable for application to variable current systems with a dc voltage of 600V and above, such as ac motors, frequency converters, switching power supplies, lighting circuits, and the like. In the related art, a desaturation detection method is generally adopted in the short circuit detection of an IGBT, i.e. whether the IGBT is shorted or not is detected by detecting the occurrence of a specific phenomenon, wherein the specific phenomenon is that the IGBT will not only exit from a saturation region but also change to a voltage when turned off under a certain short circuit current condition. Specifically, the implementation of the desaturation detection method can be generally divided into two types, one is a high-voltage diode-matched comparator and the other is a resistor chain-matched comparator. However, the desaturation detection method still presents a great risk, whatever the implementation, and the risks presented are briefly analyzed below. When the short-circuit current reaches 4 times or more of the rated current of the IGBT, the IGBT exits from the saturation region, namely the terminal voltage of the IGBT is raised to the voltage amplitude when the IGBT is turned off. After the IGBT exits the saturation region, it is in a state of "rapid increase in transient power consumption", which can be maintained for about 10 μs (i.e., 4 times the rated current of the IGBT), and the longer the short-circuit current, the shorter the time that the state is maintained. In this way, the circuit for protecting the IGBT needs to safely and reliably turn off the IGBT for the time period in which the above state is maintained, so that the IGBT can be prevented from being damaged. However, in order to prevent malfunction, the desaturation detection method usually performs filtering processing to avoid affecting the normal use of the IGBT, where the filtering time is shorter, typically 3-6 μs, under low-voltage low-power conditions, and longer, typically more than 7 μs, under high-voltage high-power conditions. It can be understood that the longer the filtering time, the greater the risk of IGBT damage, and the longer the filtering process takes, or the longer the filtering process takes, resulting in slower response speed when the IGBT is short-circuited detected/protected, so that the IGBT cannot be safely and reliably turned off by the circuit protecting the IGBT within the time maintained in the above state, resulting in IGBT damage, and in addition, even if the IGBT is not damaged, the bonding line bonded with the IGBT chip will be damaged at its bonding surface due to the contact resistance, thereby affecting the performance of the IGBT. The damage risk of the IGBT in the short circuit process is increased, and meanwhile, the safety of the IGBT is reduced. Therefore, there is a need for improvements in existing IGBT short detection/protection circuits. [ Invention ] The application provides an IGBT short circuit detection and protection circuit and a short circuit detection and protection method thereof, and aims to solve the problem of slower response speed when short circuit detection/protection is performed on an IGBT in the related art. In order to solve the technical problems, a first aspect of the embodiments of the present application provides an IGBT short-circuit detection circuit, including a sampling circuit, a comparison circuit, and a timing circuit, where the timing circuit is connected to the comparison circuit, the comparison circuit is connected to the sampling circuit, and the sampling circuit is used to connect a stray inductance between an auxiliary emitter and a power emitter in an IGBT to be detected; the sampling circuit is used for collecting the voltage of the stray inductor; the comparison circuit is used for comparing the voltage of the stray inductor with a preset reference voltage and outputting a first signal according to a comparison result; The timing circuit is used for outputting a second signal indicating whether the IGBT to be detected is short-circuited or not according to the duration of the first signal in a preset level state, wherein the duration of the first signal in the preset level s