WO2017215335A1

WO2017215335A1 - Igbt short-circuit protection circuit and method, igbt driver and igbt circuit

Info

Publication number: WO2017215335A1
Application number: PCT/CN2017/080694
Authority: WO
Inventors: 袁金荣
Original assignee: 珠海格力电器股份有限公司
Priority date: 2016-06-17
Filing date: 2017-04-17
Publication date: 2017-12-21
Also published as: CN106130520A

Abstract

Disclosed are an IGBT short-circuit protection circuit (P) and method, an IGBT driver and an IGBT circuit. The IGBT short-circuit protection circuit (P) comprises: a driving current detection unit (1) used for detecting a driving current flowing through an IGBT gate; a comparison unit (2) used for comparing the driving current with a reference current and outputting a comparison result; and a protection unit (3) used for determining whether to start short-circuit protection for an IGBT according to the comparison result. By detecting the driving current flowing through the IGBT, the self-locking of an IGBT driving circuit is controlled so as to improve the reliability of the short-circuit protection for the IGBT.

Description

IGBT short circuit protection circuit and method, IGBT driver and IGBT circuit

Technical field

The present invention relates to the field of circuit technologies, and in particular, to an IGBT short circuit protection circuit and method, an IGBT driver and an IGBT circuit.

Background technique

IGBT (Insulated Gate Bipolar Transistor) is a combination of MOSFET and bipolar transistor, which combines the advantages of these two devices. It has the advantages of simple and fast driving of MOSFET devices and bipolar. The advantages of large device capacity are thus more and more widely used in current power electronics technology. However, whether the various protection functions of the IGBT driver are feasible and perfect, whether the IGBT can be turned off in an abnormal situation in a timely manner determines the life of the IGBT to a certain extent.

The short-circuit protection of the conventional IGBT driver detects the gate voltage Vce(sat) by detecting the voltage at the collector CE terminal of the IGBT at the time of turn-on. During normal operation, the Vce(sat) value is about 2V, which does not reach the short-circuit protection threshold. When a short circuit occurs, the current flowing through the collector (ie, Ic) changes rapidly, causing Vce(sat) to rise until the short-circuit protection threshold is reached. Self-locking protection is implemented by the signal processing circuit of the IGBT driver.

However, in this method, since the external characteristic curve of the IGBT is qualitative and not quantitative when the operating current is greater than 2 times of the rated current, there may be some abnormal conditions that cause the short-circuit current to be extremely large and the short-circuit protection threshold has not been reached. No action, that is, the short circuit protection fails, thereby damaging the IGBT. Further, when the short circuit inductance is too large, the current change rate becomes very low. At this time, it is not a short circuit but an overcurrent, and in this case, the short circuit protection will also be lost.

Summary of the invention

In view of the above, the present invention provides an IGBT short circuit protection circuit and method, an IGBT driver, and an IGBT circuit, which can more reliably achieve short circuit protection for an IGBT.

According to a first aspect of the present invention, an IGBT short circuit protection circuit is provided, comprising: a driving current detecting unit for detecting a driving current flowing through an IGBT gate; and a comparing unit for comparing the driving current with a reference current And outputting a comparison result; and a protection unit configured to determine whether to initiate short-circuit protection to the IGBT according to the comparison result.

Further, the comparison unit includes a reference current supply unit for supplying the reference current, and a comparator for comparing the drive current and the reference current, and outputting Comparing results.

Further, the reference current supply unit is a storage unit for storing the reference current and providing the comparator.

Further, the reference current is a maximum value of the driving current according to the normal operation of the IGBT or a previous driving current when the IGBT driver is normally operated.

Further, when the reference current is a maximum value of the driving current according to the normal operation of the IGBT, if the comparison result output by the comparison unit indicates that the detected driving current exceeds the reference current, the protection unit Start short circuit protection;

When the reference current is the last driving current when the IGBT driver is normally operated, if the comparison result indicates that the detected driving current exceeds the predetermined range of the last driving current, the protection unit starts short-circuit protection.

Further, the protection unit includes a switch, and when the protection unit determines to start the IGBT short-circuit protection according to the comparison result, the PWM pulse is turned off by turning off the switch, thereby turning off the IGBT.

According to a second aspect of the present invention, an IGBT driver is provided, comprising: a driving unit; And the IGBT short circuit protection circuit according to any one of the above.

Further, the driving unit is a push-pull pushing stage connected to the gate of the IGBT.

According to a third aspect of the invention, there is provided an IGBT circuit comprising: an IGBT; and the IGBT driver according to any of the above.

Further, the IGBT circuit further includes an IGBT gate resistor; wherein the driving current detecting unit is disposed between the driving unit and the IGBT gate resistor.

According to a fourth aspect of the present invention, a method for protecting an IGBT short circuit includes: a driving current detecting step of detecting a driving current flowing through a gate of the IGBT; a comparing step of comparing the driving current with a reference current, and outputting Comparing the result; and a protection step of determining whether to initiate short circuit protection to the IGBT based on the comparison result.

Further, the comparing step includes a reference current providing step and a comparing sub-step; the reference current providing step providing the reference current; the comparing sub-step comparing the driving current and the reference current, and Output the comparison result.

Further, when the driver is in normal operation, the value of the driving current is sampled and saved, and the detected driving current is compared with the value of the sampled and saved driving current when the IGBT is next turned on, that is, the upper The primary drive current is compared and the result of the comparison is output.

Further, if the comparison result indicates that the detected driving current exceeds the predetermined range of the previous driving current, it indicates that the IGBT is abnormal, and in this step, the short circuit protection is started in the protection unit step.

According to the above aspect of the invention, the self-locking of the IGBT driving circuit is controlled by detecting the driving current flowing through the IGBT to achieve short-circuit protection of the IGBT. In this way, by detecting the driving current flowing through the gate of the IGBT, the prior art problem that the short-circuit protection of the high-power IGBT module can only be detected by detecting the current of the collector of the strong electric terminal of the IGBT is solved, and the short-circuit protection is The sampling point does not set the strong end of the IGBT, thus avoiding the strong and weak electric mixing of the driver. In this case, the security risks to the controller are eliminated. Further, in the case of a short-circuit protection failure or an overcurrent non-short-circuit state, the reliability of the IGBT short-circuit protection is not affected, that is, the reliability of the short-circuit protection is improved.

The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention will be further clarified.

DRAWINGS

The drawings described herein are provided to provide a further understanding of the invention, and are in no way of limiting the invention.

1 is a block diagram showing the structure of an IGBT short circuit protection circuit in accordance with a preferred embodiment of the present invention.

2 is a block diagram showing the structure of an IGBT circuit in accordance with a preferred embodiment of the present invention.

3 is a flow chart of a IGBT short circuit protection method in accordance with a preferred embodiment of the present invention.

4 is a block flow diagram of a specific embodiment of a short circuit protection method in accordance with the present invention.

detailed description

The technical solutions of the present invention will be clearly and completely described in conjunction with the specific embodiments of the present invention and the accompanying drawings. It is apparent that the described embodiments are only a part of the embodiments of the invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Before explaining the circuit structure of the present invention, the working principle of the present invention will first be explained. If the IGBT has a short-circuit fault, the gate voltage Vge also rises during the rise of the collector current Ic of the IGBT, which is caused by the Miller effect. The change in the gate voltage Vge during the short circuit causes the gate charge amount Qg to change accordingly, and the required drive current also changes. At this time, the short circuit of the IGBT module can be judged by judging the abnormal increase or fluctuation of the drive current. Moreover, some drivers are provided with a collector voltage Vce caused by suppressing a short circuit. Excessive active clamp circuit, but when the voltage Vce reaches the rated clamp voltage, it will also inject current into the gate of the IGBT, causing a change in the drive current, and thereby determining the short circuit of the IGBT module.

Based on the above principles, the solution of the present invention has been proposed, which will be described in detail below.

First, the configuration of the IGBT short-circuit protection circuit of the present invention will be described with reference to FIG. 1 is a block diagram showing the structure of an IGBT short circuit protection circuit according to the present invention. As shown in FIG. 1, the IGBT short circuit protection circuit P includes a driving current detecting unit 1, a comparing unit 2, and a protection unit 3. The drive current detecting unit 1 is for detecting a drive current flowing through the IGBT, specifically, a drive current flowing through a gate of the IGBT. The comparing unit 2 is configured to compare the driving current with a reference current and output a comparison result. The protection unit 3 is configured to determine whether to initiate short-circuit protection to the IGBT according to the comparison result, for example, controlling the driver self-locking of the IGBT to turn off the IGBT.

According to the above aspect of the invention, the self-locking of the IGBT driving circuit is controlled by detecting the driving current flowing through the IGBT to achieve short-circuit protection of the IGBT. In this way, by detecting the driving current flowing through the gate of the IGBT, the prior art problem that the short-circuit protection of the high-power IGBT module can only be detected by detecting the current of the collector of the strong electric terminal of the IGBT is solved, and the short-circuit protection is The sampling point does not set the strong end of the IGBT, thus avoiding the situation that the driver is strong and weakly mixed, and the safety hazard to the controller is eliminated. Further, in the case of a short-circuit protection failure or an overcurrent non-short-circuit state, the reliability of the IGBT short-circuit protection is not affected, that is, the reliability of the short-circuit protection is improved.

Hereinafter, each component of the protection circuit will be described one by one.

The drive current detecting unit 1 is for detecting a drive current flowing through the IGBT, specifically, a drive current flowing through a gate of the IGBT. The drive current detecting unit is, for example, an element capable of realizing current detection such as an ammeter.

The comparing unit 2 is configured to compare the driving current with a reference current and output a comparison result. In a preferred embodiment, as shown in FIG. 1, the comparison unit 2 includes a reference current supply unit 21 and a comparator 22. The reference current supply unit 21 is configured to provide the reference current, and the comparator 21 is configured to compare the drive current and the reference current, and input Compare results. In a specific embodiment, the reference current supply unit 21 is a memory or a register as a storage unit for storing the reference current and supplying it to the comparator 22.

In one embodiment, the reference current may be an empirical value set according to a driving current under normal operation of the IGBT, for example, a maximum value of a driving current under normal operation of the IGBT, or a normal operation of several seconds after the driver is started, the acquisition driving The current is calculated as the maximum value, or the calculated maximum value is added with a redundant amount, and the like. If the comparison result output by the comparison unit 2 indicates that the detected drive current exceeds the reference current, the protection unit 3 initiates short-circuit protection, for example, causing the driver to self-lock to turn off the IGBT.

In another embodiment, the reference current may also be the last driving current when the driver stored in the reference current supply unit 21 is normally operated. Specifically, when the driver is in normal operation, the value of the driving current is sampled and saved, and the value of the detected driving current and the sampled and saved driving current when the IGBT is next turned on, that is, the upper The primary drive current is compared and the result of the comparison is output. If the comparison result indicates that the detected driving current exceeds the predetermined range of the previous driving current, the predetermined range is, for example, a redundancy amount, that is, the detected driving current has a larger increase than the previous driving current. , indicating that the IGBT is abnormal, then the protection unit 3 starts short-circuit protection, for example, the driver is self-locked to turn off the IGBT. If the comparison result indicates that the detected driving current exceeds the value of the last driving current within a predetermined range, it indicates that the IGBT does not have an abnormality, the protection unit 3 does not start the short circuit protection, and the reference current supply unit 21 stores the corresponding Drive current for the next comparison.

The protection unit 3 is configured to determine whether to initiate short circuit protection of the IGBT according to the comparison result. Specifically, if the comparison result indicates that the IGBT has an abnormality, for example, the detected driving current exceeds the predetermined range of the previous driving current, the protection unit 3 initiates short-circuit protection to the IGBT, for example, the control driver performs self-locking, thereby turning off the IGBT. . Otherwise, short circuit protection is not activated.

Further, the present invention provides an IGBT driver. The IGBT driver includes a driving unit and the IGBT short circuit protection circuit. The drive unit of the IGBT driver is, for example, a push-pull push stage connected to the gate of the IGBT.

And further, an IGBT circuit according to the present invention will be described. The IGBT circuit includes an IGBT and the above IGBT driver. Wherein the IGBT short circuit protection circuit of the IGBT driver The driving current detecting unit 1 is disposed between the driving unit and the gate resistance of the IGBT.

The IGBT circuit according to the present invention will be described below in conjunction with a specific embodiment shown in FIG. As shown in FIG. 2, the IGBT circuit includes an IGBT and the IGBT driver. The IGBT driver includes a driving unit 4 and the IGBT short circuit protection circuit P. The IGBT short circuit protection circuit P includes a driving current detecting unit 1, a comparing unit 2 (including a reference current supply unit 21, a comparator 22), and a protection unit 3. The driving current detecting unit 1 is configured to detect a driving current supplied from the driving unit 4, and the comparator 22 compares the detected driving current with a reference current supplied from the reference current supply unit 21, and outputs a comparison result. The protection unit 3 activates the short circuit protection according to the comparison result, and performs self-locking of the IGBT driving circuit, for example, shielding the PMW pulse and setting a low level to turn off the IGBT. Further, the IGBT circuit includes a gate resistance Rg, and the current detecting unit 1 is disposed between the driving unit 4 and the gate resistor Rg for detecting a driving current flowing through a gate of the IGBT.

The IGBT short circuit protection method according to the present invention will be described below with reference to FIG. 3. As shown in FIG. 3, the method includes a driving current detecting step S1, a comparing step S2, and a protecting step S3. The drive current detecting step S1 detects a drive current flowing through the IGBT, specifically, a drive current flowing through the gate of the IGBT. The comparing step S2 compares the driving current with a reference current and outputs a comparison result. The protecting step S3 determines whether to initiate short-circuit protection to the IGBT according to the comparison result, for example, controlling the driver of the IGBT to self-lock to turn off the IGBT.

The comparing step S2, in a preferred embodiment, comprises a reference current providing step and a comparing sub-step. The reference current supply step stores and supplies the reference current using, for example, a memory or a register as a memory unit. The comparing substep compares the driving current with the reference current and outputs a comparison result.

As described above, in one embodiment, the reference current may be an empirical value set according to a driving current under normal operation of the IGBT, for example, a maximum value of a driving current under normal operation of the IGBT, or normal after the driver is started. Work for a few seconds, collect the drive current and calculate the maximum value, or the calculated maximum value and then add a redundant amount of values. If the comparison result outputted in the comparison step S2 indicates that the detected drive current exceeds the reference current, then in the protection step S3, short-circuit protection is initiated, for example, causing the driver to self-lock to turn off the IGBT.

In another embodiment, the reference current may also be the last drive current when the saved driver is in normal operation. Specifically, when the driver is in normal operation, the value of the driving current is sampled and saved, and the value of the detected driving current and the sampled and saved driving current when the IGBT is next turned on, that is, the upper The primary drive current is compared and the result of the comparison is output. If the comparison result indicates that the detected driving current exceeds the predetermined range of the previous driving current, the predetermined range is, for example, a redundancy amount, that is, the detected driving current has a larger increase than the previous driving current. If the IGBT is abnormal, then at step S3, the short-circuit protection is started, for example, the driver is self-locked to turn off the IGBT. If the comparison result indicates that the detected driving current exceeds the value of the last driving current within a predetermined range, it indicates that the IGBT does not have an abnormality, then in the protection step S3, the short-circuit protection is not activated, and the reference current supply step is stored. The corresponding drive current is used for the next comparison.

4 is a block flow diagram showing a specific embodiment of a short circuit protection method in accordance with the present invention. As shown in FIG. 4, the specific process of the short circuit protection method will be described by taking the operation process of the IGBT circuit shown in FIG. 2 as an example. The IGBT driver operates while the short circuit protection circuit is in operation. First, the first normal drive current signal is stored, and the subsequent drive current, that is, the detected drive current, is further sampled. Further, the detected driving current is compared with the previously stored driving current, and it is determined whether the driving current is abrupt or abnormal. If abnormal, the switching switch is turned on to block the PWM pulse, thereby starting IGBT short-circuit protection.

The IGBT short circuit protection circuit and method, IGBT driver, and IGBT circuit of the present invention have been described above. By detecting the driving current flowing through the gate of the IGBT, the prior art problem that the short-circuit protection of the high-power IGBT module can only be detected by detecting the current of the collector of the IGBT strong electric terminal is solved, and the sampling due to the short-circuit protection is solved. The point does not set the strong end of the IGBT, thus avoiding the situation that the driver is strong and weakly mixed, eliminating the safety hazard to the controller. Further, in the case of a short-circuit protection failure or an overcurrent non-short-circuit state, the reliability of the IGBT short-circuit protection is not affected, that is, the reliability of the short-circuit protection is improved.

In summary, those skilled in the art will readily understand that the above advantageous modes can be freely combined and superimposed without conflict.

The above is only a preferred embodiment of the present invention and is not intended to be in any form for the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments in accordance with the technical spirit of the present invention are still within the scope of the technical solutions of the present invention.

Claims

An IGBT short circuit protection circuit, comprising:

a driving current detecting unit for detecting a driving current flowing through the gate of the IGBT;

a comparison unit configured to compare the drive current with a reference current and output a comparison result;

And a protection unit, configured to determine, according to the comparison result, whether to initiate short circuit protection to the IGBT.
The IGBT short circuit protection circuit according to claim 1, wherein

The comparison unit includes a reference current supply unit for supplying the reference current, and a comparator for comparing the drive current with the reference current and outputting a comparison result.
The IGBT short circuit protection circuit according to claim 2, wherein

The reference current supply unit is a storage unit for storing the reference current and providing the comparator.
The IGBT short circuit protection circuit according to claim 2 or 3, characterized in that

The reference current is a maximum value of the driving current according to the normal operation of the IGBT or a previous driving current when the IGBT driver is normally operated.
The IGBT short circuit protection circuit according to claim 4, wherein

When the reference current is the maximum value of the driving current according to the normal operation of the IGBT, if the comparison result of the comparison unit output indicates that the detected driving current exceeds the reference current, the protection unit starts short-circuit protection. ;

When the reference current is the last driving current when the IGBT driver is normally operated, if the comparison result indicates that the detected driving current exceeds the predetermined range of the last driving current, the protection unit starts short-circuit protection.
The IGBT short circuit protection circuit according to any one of claims 1 to 5, characterized in that

The protection unit includes a switching switch. When the protection unit determines to activate the IGBT short-circuit protection according to the comparison result, the PWM pulse is turned off by turning off the switching switch, thereby turning off the IGBT.
An IGBT driver, comprising:

A driving unit; and the IGBT short circuit protection circuit according to any one of claims 1 to 6.
The IGBT driver of claim 7 wherein:

The drive unit is a push-pull push stage connected to the gate of the IGBT.
An IGBT circuit, comprising:

IGBT; and

The IGBT driver according to claim 7 or 8.
The IGBT circuit according to claim 9, further comprising an IGBT gate resistance;

The driving current detecting unit is disposed between the driving unit and the IGBT gate resistor.
An IGBT short circuit protection method, comprising:

Driving a current detecting step to detect a driving current flowing through a gate of the IGBT;

a comparison step of comparing the drive current with a reference current and outputting a comparison result;

And a protection step of determining whether to initiate short circuit protection of the IGBT according to the comparison result.
The method of claim 11 wherein:

The comparing step includes a reference current providing step and a comparing sub-step; the reference current providing step providing the reference current; the comparing sub-step, comparing the driving current with the reference current, and outputting a comparison result .
A method according to claim 11 or 12, wherein

While the driver is in normal operation, the value of the driving current is sampled and saved, and the detected driving current and the value of the sampled and saved driving current when the IGBT is next turned on, that is, the last driving current Compare and output the result of the comparison.
The method of claim 13 wherein:

If the comparison result indicates that the detected driving current exceeds the predetermined range of the previous driving current, it indicates that the IGBT is abnormal, and then the short circuit protection is started in the protection unit step.