CN111257716B

CN111257716B - IGBT over-current detection circuit, chip and electronic equipment

Info

Publication number: CN111257716B
Application number: CN202010113334.5A
Authority: CN
Inventors: 陈坤裕; 李育刚; 曾奕彰; 应秋菊
Original assignee: Xiamen Kehua Hengsheng Co Ltd; Zhangzhou Kehua Technology Co Ltd
Current assignee: Xiamen Kehua Hengsheng Co Ltd; Zhangzhou Kehua Technology Co Ltd
Priority date: 2020-02-24
Filing date: 2020-02-24
Publication date: 2022-06-10
Anticipated expiration: 2040-02-24
Also published as: CN111257716A

Abstract

The invention is suitable for the technical field of circuits, and provides an IGBT over-current detection circuit, a chip and electronic equipment, wherein the IGBT over-current detection circuit comprises: the circuit comprises a controller, a current limiting resistor, a switching device, a driving resistor and a voltage dividing resistor. The current limiting resistor is connected between an IGBT driving signal output end of the controller and a first end of the switching device, and the first end of the switching device is also connected with an IGBT overcurrent detection signal input end of the controller; and the second end of the switching device is used as the detection end of the IGBT overcurrent detection circuit after passing through the divider resistor and is used for being connected with the IGBT collector to be detected. The IGBT over-current detection circuit, the chip and the electronic equipment provided by the embodiment of the invention can be used for over-current protection of the RB-IGBT, and the problem that the traditional IGBT short-circuit protection circuit in the prior art is not suitable for the over-current protection of the RB-IGBT is solved.

Description

IGBT over-current detection circuit, chip and electronic equipment

Technical Field

The invention belongs to the technical field of circuits, and particularly relates to an IGBT overcurrent detection circuit, a chip and electronic equipment.

Background

Fig. 1 shows a conventional IGBT (Insulated Gate Bipolar Transistor, abbreviated as IGBT) short-circuit protection circuit, whose operation process is briefly described as follows:

(1) when the IGBT is turned off, S is turned on, the current source is bypassed by S, the same-phase end of the comparator is clamped at 0 potential, and no short-circuit fault signal is output. The diode D blocks the effect of the high voltage at the collector of the IGBT on the detection circuit.

(2) When the IGBT is turned on, S is turned off, and the current source forms a loop via the diode D and the IGBT. Because the tube voltage drop Vce is very low when the IGBT is in saturated conduction, the in-phase end of the comparator is clamped at a low potential, and a short-circuit fault signal is not output.

(3) When the IGBT is short-circuited, saturation is rapidly released and Vce rises. When the same-phase end potential of the comparator exceeds the opposite-phase end, a short-circuit fault signal is output, and protection action is triggered.

The conventional IGBT cannot withstand the back voltage, and generally, the anti-parallel diode ensures that Vce is clamped above 0V, so that a negative potential does not appear at point a in fig. 1. When the RB-IGBT (Reverse Blocking IGBT) operates under a Reverse Blocking condition, the emitter potential is higher than the collector potential to form a current loop shown by a dotted line in fig. 2, which causes a negative potential at a point a in fig. 2, and the negative potential will damage the driving protection circuit.

Disclosure of Invention

In view of this, embodiments of the present invention provide an IGBT overcurrent detection circuit, a chip, and an electronic device, so as to solve the problem that a conventional IGBT short-circuit protection circuit in the prior art is not suitable for RB-IGBT overcurrent protection.

According to a first aspect, an embodiment of the present invention provides an IGBT over-current detection circuit, including: the circuit comprises a current limiting resistor, a switching device, a driving resistor and a voltage dividing resistor; one end of the current-limiting resistor is connected with an IGBT driving signal output end of the controller, the IGBT driving signal output end is used for being connected with an IGBT driving end to be detected, and the other end of the current-limiting resistor is connected with a first end of the switch device and an IGBT overcurrent detection signal input end of the controller; the control end of the switching device is connected with a reference potential through the driving resistor, and the second end of the switching device is used as the detection end of the IGBT overcurrent detection circuit after passing through the divider resistor and is connected with the IGBT collector to be detected.

According to the IGBT overcurrent detection circuit provided by the embodiment of the invention, whether the IGBT overcurrent detection circuit outputs a high level to the IGBT overcurrent detection signal input end of the controller or not is controlled through the on or off of the switching device and the potential of the first section of the switching device, so that the controller is triggered to identify whether the IGBT has a short-circuit fault or not. When the IGBT over-current detection circuit provided by the embodiment of the invention is used for over-current protection of the RB-IGBT, under the condition of reverse blocking of the RB-IGBT, a switching device, such as a base electrode-collector electrode PN junction in a triode, bears negative high voltage of the RB-IGBT, and negative potential is not introduced into a controller, so that the IGBT driving protection circuit is prevented from being damaged by the negative potential, and the problem that the traditional IGBT short-circuit protection circuit in the prior art is not suitable for the over-current protection of the RB-IGBT is solved. In addition, when the IGBT driving signal output end of the controller outputs high level, current can flow to the reference potential through a current-limiting resistor and a switching device, such as a PN junction conducted in a triode, so that an equivalent circuit similar to a traditional diode isolation overcurrent sampling circuit is formed, and overcurrent protection of the IGBT is realized.

With reference to the first aspect, in a first implementation manner of the first aspect, the IGBT overcurrent detection circuit further includes a first diode; the first diode is connected with the current-limiting resistor in parallel, and the cathode of the first diode is connected with the IGBT driving signal output end. .

According to the IGBT overcurrent detection circuit provided by the embodiment of the invention, the first diode is additionally arranged between the switching device and the IGBT driving signal output end of the controller, so that when the IGBT driving signal output end outputs a low level, namely the IGBT does not work, the potential of the emitter of the switching device such as a triode can be clamped at the low level, and the switching device such as the triode is prevented from outputting a high level to the IGBT overcurrent detection signal input end.

With reference to the first embodiment of the first aspect, in a second embodiment of the first aspect, the current limiting resistor, the voltage dividing resistor and the IGBT driving signal output end satisfy the following regulation: when the switching device is conducted, Vout is more than or equal to Ve and more than Vc, wherein Vout is the electric potential of the IGBT driving signal output end, Ve is the electric potential of the first end of the switching device, and Vc is the electric potential of the second end of the switching device.

With reference to the second embodiment of the first aspect, in a third embodiment of the first aspect, the IGBT overcurrent detection circuit further includes a second diode; the second diode is connected between the second terminal of the switching device and the detection terminal, and a conduction direction of the second diode is directed to the detection terminal.

According to the IGBT overcurrent detection circuit provided by the embodiment of the invention, the second diode is additionally arranged between the switching device and the IGBT, so that when the IGBT driving signal output end outputs a low level, namely the IGBT does not work, the positive high voltage of the IGBT can be isolated.

With reference to the first aspect or any one of the first to third embodiments of the first aspect, in a fourth embodiment of the first aspect, the IGBT to be detected is an RB-IGBT, the RB-IGBT includes two sub-IGBTs connected in inverse parallel, and the IGBT collector, the IGBT emitter, and the IGBT driver to be detected are different connection terminals of the same sub-IGBT.

With reference to the first aspect or any one of the first to the third embodiments of the first aspect, in a fifth embodiment of the first aspect, the switching device is a PNP type triode.

According to a second aspect, an embodiment of the present invention provides a chip, where the chip includes the IGBT over-current detection circuit according to the first aspect or any implementation manner of the first aspect.

According to a third aspect, an embodiment of the present invention provides an electronic device, which includes the IGBT overcurrent detection circuit according to the first aspect or any implementation manner of the first aspect.

According to a fourth aspect, embodiments of the present invention provide another electronic device, which includes the chip according to the third aspect.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a schematic diagram of a conventional IGBT short-circuit protection circuit;

FIG. 2 is a schematic circuit diagram of a conventional IGBT short-circuit protection applied to RB-IGBTs;

fig. 3 is a schematic circuit diagram of a specific example of an IGBT overcurrent detection circuit according to an embodiment of the present invention;

fig. 4 is a circuit schematic diagram of another specific example of the IGBT overcurrent detection circuit provided by the embodiment of the present invention;

fig. 5 is a circuit schematic diagram of a third specific example of the IGBT overcurrent detection circuit according to the embodiment of the present invention;

fig. 6 is a circuit schematic diagram of a fourth specific example of the IGBT overcurrent detection circuit according to the embodiment of the present invention;

FIG. 7 is a diagram illustrating an exemplary chip structure provided by an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a specific example of an electronic device provided by the embodiment of the present invention;

fig. 9 is a schematic structural diagram of another specific example of the electronic device according to the embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

In order to explain the technical means of the present invention, the following description will be given by way of specific examples.

An embodiment of the present invention provides an IGBT over-current detection circuit, as shown in fig. 3, the IGBT over-current detection circuit may include a controller U, a current-limiting resistor R1, a triode Q1, and a voltage-dividing resistor R2.

Specifically, one end of the current limiting resistor R1 is connected to an IGBT drive signal output terminal OUT of the controller U, the other end of the current limiting resistor R1 is connected to an emitter of the transistor Q1, and the emitter of the transistor Q1 is connected to an IGBT overcurrent detection signal input terminal IN of the controller U. The base of the transistor Q1 is connected to a reference potential, the collector of the transistor Q1 is connected to one end of a voltage dividing resistor R2, and the other end of the voltage dividing resistor R2 is connected to the collector of the IGBT Q2. The IGBT shown in fig. 3 is an RB-IGBT, and when reverse blocking occurs in the RB-IGBT, a large negative voltage is generated between the collector and emitter of the RB-IGBT.

The RB-IGBT is a device with two sub-switches connected in parallel, and the two sub-switches respectively correspond to driving signals. When the upper sub-switch is conducted, the lower sub-switch forms reverse high voltage or reverse blocking; when the lower subswitch is conducted, the upper subswitch forms reverse high voltage or reverse blocking. The RB-IGBT forward blocking corresponds to the Q1 being turned on and Q2 and Q3 being turned off in the processes of FIG. 3 to FIG. 6; reverse blocking of the RB-IGBT corresponds to conduction of the tubes Q3 and Q2 in the graphs of FIGS. 3 to 6, and turn off of the tubes Q1 and Q2; the RB-IGBT is turned on corresponding to the Q1 and Q2 lower tubes in the graphs of FIGS. 3 to 6 being turned on, and the Q3 and the Q2 upper tubes being turned off. The switch combination modes corresponding to the forward blocking, reverse blocking and conducting of the RB-IGBT are only three switch modes of the circuits shown in fig. 3 to 6, and there may be other control modes that can also implement the forward blocking, reverse blocking and conducting of the RB-IGBT.

For the IGBT overcurrent detection circuit shown in fig. 3, when the IGBT Q2 is driven high, the current flows from the current limiting resistor R1 to the reference potential through the PN junction of the transistor Q1, the PN junction of the transistor Q1 is forward biased, and is in a conducting state, and correspondingly, the emitter potential Ve of the transistor Q1 is about 0.7V (calculated on the premise that the IGBT collector voltage is limited to 0V). Because the emitter of the triode Q1 is connected with the IGBT overcurrent detection signal input terminal IN of the controller U, the potential of the IGBT overcurrent detection signal input terminal IN is also about 0.7V, which is not enough to trigger the overcurrent protection action of the controller U. A user may preset a trigger critical point at which the controller U performs the overcurrent protection operation, for example, the trigger critical point is set to 1V, and the overcurrent protection operation of the controller U is triggered only when the potential at the input terminal IN of the IGBT overcurrent detection signal reaches 1V or more.

When the IGBT Q2 is driven to be at low level, the triode Q1 is cut off; when a potential difference Vce between a collector and an emitter of the IGBT Q2 is positive high voltage, the emitter potential Ve of the triode Q1 is about 0V; when the potential difference Vce between the collector and the emitter of the IGBT Q2 is a negative high voltage, there may be a reverse current loop that causes a reverse high voltage to the chip or device, and even the reverse high voltage may exceed the withstand voltage of the chip or device, and damage the chip or device. Because the emitter of the triode Q1 is connected with the IGBT overcurrent detection signal input end IN of the controller U, the potential of the IGBT overcurrent detection signal input end IN is about 0V, and the overcurrent protection action of the controller U cannot be triggered. When the IGBT Q2 is an RB-IGBT and is in reverse cut-off, the negative high voltage generated by the RB-IGBT is born by the base-collector PN junction in the triode Q1.

When the IGBT Q2 is driven to be at high level, the triode Q1 is conducted; if the RB-IGBT is short-circuited, the potential difference Vce between the collector and the emitter thereof rapidly rises, so that the emitter potential Ve of the transistor Q1 rapidly rises. Because the emitter of the triode Q1 is connected with the IGBT overcurrent detection signal input end IN of the controller U, the potential of the IGBT overcurrent detection signal input end IN also rises rapidly. When the potential of the IGBT overcurrent detection signal input end IN reaches the overcurrent detection action voltage of the controller U, the controller U executes the IGBT overcurrent detection protection action.

It should be noted that, IN fig. 3, the PNP transistor Q1 is selected as the switching device to control the potential of the input terminal IN of the IGBT overcurrent detection signal, IN practical applications, a user may also select other switching devices, such as a field effect transistor, as needed, which is not limited IN this embodiment of the present invention. Fig. 5 is a schematic circuit diagram of a specific example of implementing the IGBT overcurrent detection by using a switching device such as a triode or a field effect transistor. IN the IGBT overcurrent detection circuit shown IN fig. 5, one end of the current limiting resistor R1 is connected to the IGBT drive signal output terminal OUT of the controller U, and the other end of the current limiting resistor R1 is connected to the IGBT overcurrent detection signal input terminal IN of the controller U. The first end of the switching device T is connected with an IGBT overcurrent detection signal input end IN of the controller U, and the second end of the switching device T is used for being connected with the driving end of the IGBT to be detected.

Fig. 6 is a schematic circuit diagram of a specific example of implementing the IGBT overcurrent detection by using a field-effect transistor Q3 instead of the transistor Q1 in fig. 3. IN the IGBT overcurrent detection circuit shown IN fig. 6, one end of the current-limiting resistor R1 is connected to the IGBT drive signal output terminal OUT of the controller U, the other end of the current-limiting resistor R1 is connected to the drain of the field-effect transistor Q3, and the drain of the field-effect transistor Q3 is also connected to the IGBT overcurrent detection signal input terminal IN of the controller U. The gate of the fet Q3 may be directly connected to the reference potential, or the gate of the fet Q3 may be connected to the reference potential via the driving resistor R3. The source of the field effect transistor Q3 is connected to one end of the voltage dividing resistor. The other end of the voltage dividing resistor may be directly connected to the collector of the IGBT, or the other end of the voltage dividing resistor may be connected to the collector of the IGBT through the second diode D2. Further, a resistor R5 may be provided between the drain and gate of the field effect transistor Q3.

In the IGBT overcurrent detection circuit shown in fig. 6, when the drive of the IGBT Q2 to be detected is at a high level, the field-effect transistor Q3 is turned on, forming an equivalent circuit that is the same as the conventional diode isolation overcurrent sampling, and the overcurrent detection voltage value of the IGBT Q2 to be detected is approximately equal to the actual value plus 0.7V. When the IGBT Q2 to be detected is driven to be in a low level, the field effect transistor Q3 is cut off; when Vce is a positive high voltage, the diode D2 functions to isolate the high voltage, and the leakage current on the diode D2 is brought to the reference potential 0V through the resistor R3 and the diode D3; at this time, the over-current detection voltage value of IGBTQ2 to be detected is approximately equal to 0V. When the IGBT Q2 to be detected is driven to be at a low level, the field effect transistor Q3 is cut off; when Vce is negative high voltage, Vgd of the field effect transistor Q3 bears high voltage state, and the over-current detection voltage value of the IGBT Q2 to be detected is approximately equal to 0V.

The IGBT over-current detection circuit provided by the embodiment of the invention controls whether the IGBT over-current detection circuit outputs high level to the IGBT over-current detection signal input end of the controller or not through the conduction or the cut-off of the triode and the potential of the emitter of the triode, thereby triggering the controller to identify whether the IGBT has short circuit fault or not. When the IGBT over-current detection circuit provided by the embodiment of the invention is used for over-current protection of the RB-IGBT, under the condition of reverse blocking of the RB-IGBT, the negative high voltage of the RB-IGBT is borne by a base electrode-collector electrode PN junction in a triode, and a negative potential cannot be introduced into a controller, so that the IGBT driving protection circuit is prevented from being damaged by the negative potential, and the problem that the traditional IGBT short-circuit protection circuit in the prior art is not suitable for the over-current protection of the RB-IGBT is solved.

The embodiment of the invention also provides another IGBT overcurrent detection circuit, as shown in fig. 4, the IGBT overcurrent detection circuit includes all devices in the IGBT overcurrent detection circuit shown in fig. 3, and for avoiding repetition, details are not repeated here. Compared with the IGBT over-current detection circuit shown in fig. 3, the IGBT over-current detection circuit shown in fig. 4 further includes a first diode D1. In one embodiment, the anode of the first diode D1 is connected to the emitter of the transistor Q1, and the cathode of the first diode D1 is connected to the IGBT drive signal output terminal OUT of the controller U. Through add first diode D1 between the IGBT drive signal output OUT at triode Q1 and controller U for when IGBT drive signal output OUT exports the low level, when the IGBT is OUT of work promptly, can clamp the electric potential of triode Q1 projecting pole at the low level, thereby avoid triode Q1 to the IGBT detection signal input IN output high level that overflows. Similarly, referring to fig. 4, a first diode D1 may be added at a corresponding position in fig. 6.

Optionally, as shown in fig. 4, the IGBT overcurrent detection circuit may further include a second diode D2. In one embodiment, the anode of the second diode D2 is connected to the collector of the transistor Q1, and the cathode of the second diode D2 is connected to the collector of the IGBT Q2. By additionally arranging the second diode D2 between the triode Q1 and the IGBT Q2, when the IGBT driving signal output end OUT outputs a low level, namely the IGBT does not work, the positive high voltage of the IGBT is isolated. Similarly, referring to fig. 4, a second diode D2 may be further added at a corresponding position in fig. 6.

Optionally, as shown in fig. 4, the IGBT overcurrent detection circuit may further include a driving resistor R3. In one embodiment, the driving resistor R3 is connected between the base of transistor Q1 and a reference potential. The drive resistor is connected in series with the base electrode of the triode Q1, so that the drive voltage of the triode Q1 is regulated and controlled, and the overall reliability of the IGBT overcurrent detection circuit is improved. Similarly, referring to fig. 4, a driving resistor R3 may be added at a corresponding position in fig. 6.

The embodiment of the present invention further provides a chip, as shown in fig. 7, where the chip 200 includes the IGBT overcurrent detection circuit 100 shown in fig. 3 or fig. 4. In the chip 200, the IGBT over-current detection circuit 100 may be used for over-current protection of various types of IGBTs in the chip 200.

An embodiment of the present invention further provides an electronic device, as shown in fig. 8, where the electronic device 300 includes the IGBT overcurrent detection circuit 100 shown in fig. 3 or fig. 4. In the electronic device 300, the IGBT overcurrent detection circuit 100 can be used for overcurrent protection of various types of IGBTs in the electronic device 300.

Another electronic device is provided in the embodiment of the present invention, as shown in fig. 9, the electronic device 300 includes the chip 200 shown in fig. 7. Since the chip 200 includes the IGBT overcurrent detection circuit 100 shown in fig. 3 or fig. 4, in the electronic device 300, the chip 200 and the IGBT overcurrent detection circuit 100 included therein may be used for overcurrent protection of various IGBTs in the electronic device 300.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.

Claims

1. The utility model provides a IGBT overflows detection circuitry, includes the controller, its characterized in that still includes:

the circuit comprises a current limiting resistor, a switching device, a driving resistor and a voltage dividing resistor;

one end of the current-limiting resistor is connected with an IGBT driving signal output end of the controller, the IGBT driving signal output end is used for being connected with an IGBT driving end to be detected, and the other end of the current-limiting resistor is connected with a first end of the switch device and an IGBT overcurrent detection signal input end of the controller;

the control end of the switching device is connected with a reference potential through the driving resistor, the second end of the switching device is used as the detection end of the IGBT overcurrent detection circuit after passing through the divider resistor and is used for being connected with the collector electrode of the IGBT to be detected, and the IGBT to be detected is RB-IGBT.

2. The IGBT overcurrent detection circuit according to claim 1, further comprising a first diode;

the first diode is connected with the current-limiting resistor in parallel, and the cathode of the first diode is connected with the IGBT driving signal output end.

3. The IGBT overcurrent detection circuit according to claim 2, wherein the current limiting resistor, the voltage dividing resistor, and the IGBT drive signal output satisfy the following regulation: when the switching device is conducted, Vout is more than or equal to Ve and more than Vc, wherein Vout is the electric potential of the IGBT driving signal output end, Ve is the electric potential of the first end of the switching device, and Vc is the electric potential of the second end of the switching device.

4. The IGBT overcurrent detection circuit according to claim 3, further comprising a second diode;

the second diode is connected between the second terminal of the switching device and the detection terminal, and a conduction direction of the second diode is directed to the detection terminal.

5. The IGBT over-current detection circuit according to any one of claims 1 to 4, wherein the RB-IGBT comprises two sub-IGBTs connected in anti-parallel, and the IGBT collector electrode, the IGBT emitter electrode and the IGBT driving electrode to be detected are different connection terminals of the same sub-IGBT.

6. The IGBT over-current detection circuit according to any one of claims 1 to 4, wherein the switching device is a PNP type triode.

7. A chip comprising the IGBT over-current detection circuit according to any one of claims 1 to 6.

8. An electronic device characterized in that the electronic device comprises the IGBT overcurrent detection circuit according to any one of claims 1 to 6.

9. An electronic device, characterized in that the electronic device comprises a chip according to claim 7.