A short circuit protection circuit and electrical equipment

Abstract

The present invention discloses a short-circuit protection circuit and electrical equipment. The circuit includes: a detection module, whose first input end is connected to the gate of the power switch device, and is used to control whether it is powered on according to the on-off of the power switch device, and whose second input end is connected to the drain of the power switch device, and is used to detect whether the power switch device is short-circuited, and outputs a first voltage signal when the power switch device is normally turned on, and outputs a second voltage signal when the power switch device is short-circuited; a protection module, whose input end is connected to the detection module, and whose output end is connected to the driver chip of the power switch device, and is used to block the drive signal of the driver chip after the detection module outputs the second voltage signal, so that the power switch device is turned off. Through the present invention, costs can be saved, and false triggering can be avoided, and the accuracy of short-circuit protection can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a short circuit protection circuit and electrical equipment. Background Art

[0002] Power switching devices (such as insulated gate bipolar transistors, IGBTs) are commonly used electronic devices and are widely used in products such as power supplies, household appliances, and air conditioners, playing a key role. In power electronic systems, short circuits are divided into Class I short circuits (short circuits within a bridge arm) and Class II short circuits (short circuits between bridge arms). Class I short circuits are mainly caused by hardware failure or software failure that leads to direct conduction between the upper and lower tubes of the same bridge arm, while Class II short circuits are caused by direct conduction between different bridge arms due to phase-to-phase short circuits or relative ground short circuits. In the current technical solution, Class II short circuits are generally performed by monitoring the grid current through a current sensor for overcurrent protection. For the Class I short circuit problem, the desaturation mechanism is generally used to monitor the saturation voltage drop Vce (sat) of the IGBT using a peripheral circuit. Figure 1 It is a peripheral circuit used in the prior art to implement short-circuit protection, which consists of a blanking capacitor, a high-voltage diode, and a resistor. This solution generally requires the use of an integrated driver chip with an auxiliary desaturation detection function, which is relatively expensive; at the same time, due to the relatively high junction capacitance of the high-voltage diode, the displacement current generated by the diode is likely to interfere with other electronic devices every time the IGBT is switched, causing false alarms for short-circuit protection and causing problems with the accuracy of short-circuit protection.

[0003] With respect to the problems of high cost and low accuracy of short-circuit protection of power switch devices in the prior art, no effective solution has been proposed so far. Summary of the invention

[0004] A short-circuit protection circuit and an electrical device are provided in the embodiments of the present invention to solve the problems of high cost and low accuracy of short-circuit protection of power switch devices in the prior art.

[0005] In order to solve the above technical problems, the present invention provides a short-circuit protection circuit, which is applied to a power switch device, wherein the short-circuit protection circuit comprises:

[0006] A detection module, wherein a first input end thereof is connected to the gate of the power switch device, and is used to control whether the power switch device is powered on according to the on-off state of the power switch device, and a second input end thereof is connected to the drain of the power switch device, and is used to detect whether the power switch device is short-circuited, and outputs a first voltage signal when the power switch device is normally turned on, and outputs a second voltage signal when the power switch device is short-circuited;

[0007] The protection module has an input end connected to the detection module and an output end connected to the driver chip of the power switch device, and is used to block the drive signal of the driver chip after the detection module outputs the second voltage signal to turn off the power switch device.

[0008] Furthermore, the detection module includes:

[0009] A detection capacitor, a first end of which is connected to the input end of the protection module and a second end of which is grounded;

[0010] A charging unit, a first end of which is connected to the drain of the power switch device, and a second end of which is connected between the detection capacitor and the input end of the protection module; the charging unit includes a first switch, which is used to control whether the charging unit charges the detection capacitor by turning on and off;

[0011] A voltage divider unit, a first end of which is connected between the gate of the power switching device and the driving resistor, a second end of which is connected to the emitter of the first switch, and a third end of which is connected to the base of the first switch, and the voltage divider unit is used to control the on and off of the first switch according to the gate voltage of the power switching device.

[0012] Furthermore, the charging unit further includes:

[0013] A first resistor and a second resistor, wherein the first end of the first resistor is connected to the drain of the power switch device, the second end is connected to the first end of the second resistor through the collector and emitter of the first switch in sequence, and the second end of the second resistor is connected between the detection capacitor and the input end of the protection module.

[0014] Furthermore, the voltage dividing unit comprises:

[0015] A third resistor and a fourth resistor, wherein the first end of the third resistor is connected between the gate of the power switching device and the driving resistor, the second end is connected to the first end of the fourth resistor, and the second end of the fourth resistor is connected between the emitter of the first switch and the second resistor; the line between the third resistor and the fourth resistor is connected to the base of the first switch.

[0016] Furthermore, the detection module also includes:

[0017] A clamping element, a first end of which is connected to the emitter of the first switch, and the other end of which is connected to the high level pin of the driving chip.

[0018] Furthermore, the protection module includes:

[0019] A comparator, wherein a first input terminal of the comparator is connected to the output terminal of the detection module, a second input terminal of the comparator is input with a reference voltage, and an output terminal of the comparator is connected to the base of the second switch via a fifth resistor, and the first input terminal of the comparator is the input terminal of the protection module;

[0020] The collector of the second switch is connected to an external voltage through a sixth resistor, and the emitter of the second switch is grounded. The line between the collector of the second switch and the sixth resistor is connected to a high level pin of the driving chip.

[0021] Furthermore, the protection module also includes:

[0022] A seventh resistor, a first end of which is connected to the collector of the second switch, and a second end of which is connected to the base of the second switch, is used to keep the base voltage of the second switch stable.

[0023] Furthermore, the circuit further comprises:

[0024] A reference voltage source has a first end connected to the high voltage level pin of the driver chip, a second end connected to the ground, and a third end connected to the second input end of the comparator. The reference voltage source is used to output a reference voltage to the second input end of the comparator.

[0025] Furthermore, the reference voltage source comprises:

[0026] An eighth resistor and a ninth resistor, wherein the first end of the eighth resistor is connected to the high voltage level pin of the driving chip, the second end is connected to the first end of the ninth resistor, the second end of the ninth resistor is grounded, and the line between the eighth resistor and the ninth resistor is connected to the second input terminal of the comparator.

[0027] Furthermore, the circuit further comprises:

[0028] The third switch has a base connected between the output pin of the driving chip and the driving resistor through a tenth resistor, an emitter connected to the gate of the power switch device, and a collector grounded.

[0029] The present invention further provides an electrical device, comprising a power switch device and a drive chip, characterized in that the electrical device also comprises the above-mentioned short-circuit protection circuit.

[0030] Furthermore, the electrical equipment includes at least one of the following:

[0031] Air conditioners, washing machines, refrigerators, water heaters, fans, dryers, air purifiers, water purifiers, and water purifiers.

[0032] By applying the technical solution of the present invention, a detection module is used to detect whether a power switch device is short-circuited. When the power switch device is normally turned on, a first voltage signal is output, and when the power switch device is short-circuited, a second voltage signal is output; a protection module, whose input end is connected to the detection module and whose output end is connected to a driver chip of the power switch device, is used to block the drive signal of the driver chip after the detection module outputs the second voltage, so that the power switch device is turned off. This solution is applicable to ordinary driver chips and can save costs. At the same time, the combination of the detection module and the protection module can avoid false triggering and improve the accuracy of short-circuit protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a peripheral circuit used in the prior art to realize short-circuit protection;

[0034] Figure 2 is a structural diagram of a short-circuit protection circuit according to an embodiment of the present invention;

[0035] Figure 3 FIG. 4 is a structural diagram of a short circuit protection circuit according to another embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0038] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0039] It should be understood that although the terms first, second, third, etc. may be used to describe switches in the embodiments of the present invention, the switches should not be limited to these terms. These terms are only used to distinguish switches arranged at different positions. For example, without departing from the scope of the embodiments of the present invention, the first switch may also be referred to as the second switch, and similarly, the second switch may also be referred to as the first switch.

[0040] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0041] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0042] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0043] Example 1

[0044] This embodiment provides a short circuit protection circuit, which is applied to a power switch device. Figure 2 : is a structural diagram of a short-circuit protection circuit according to an embodiment of the present invention, wherein the driving circuit of the power switch device includes: a driving chip U and a driving resistor Rg, the driving chip U includes a signal input pin PWM for inputting a PWM signal, a high level pin VCC, an output pin Vo and a low level pin VEE, the output pin Vo is connected to a gate G of a power switch device (taking ICBT as an example in this embodiment), the low level pin VEE is connected to a source S of an IGBT, when the PWM signal is at a high level, the output pin Vo is connected to the high level pin VCC, outputs a high level signal, and drives the IGBT to turn on, when the PWM signal is at a low level, the output pin Vo is connected to the low level pin VEE, outputs a low level signal, and controls the IGBT to turn off.

[0045] like Figure 2As shown, the short-circuit protection circuit includes: a detection module 1, a first input end of the detection module 1 is connected to the gate G of the IGBT, and is used to control whether it is powered on according to the on-off of the IGBT, and a second input end of the detection module 1 is connected to the drain D of the IGBT, and is used to detect whether the IGBT is short-circuited. When the IGBT is normally turned on, a first voltage signal is output, and when the IGBT is short-circuited, a second voltage signal is output;

[0046] The protection module 2 has an input end connected to the output end of the detection module 1 and an output end connected to the high level pin VCC of the IGBT driver chip U, and is used to block the drive signal of the driver chip U to turn off the IGBT after the detection module 1 outputs the second voltage signal.

[0047] When the IGBT is in the off state, the detection module 1 is not powered on. When the IGBT is normally turned on, the detection module 1 is powered on, and it detects that the maximum voltage of the drain D of the IGBT is the saturation voltage of the IGBT. At this time, the protection circuit 2 is not triggered to work, and the driver chip U normally outputs a high-level signal or a low-level signal according to the input PWM signal. When the IGBT is short-circuited, the voltage of its drain D will increase to a level higher than the saturation voltage of the IGBT. After the detection module 1 detects that the voltage of the IGBT is higher than the saturation voltage of the IGBT, the protection circuit 2 is triggered to work, and the drive signal of the driver chip U is blocked, so that the driver chip U always outputs a low-level signal, thereby controlling the IGBT to turn off.

[0048] The short-circuit protection circuit of this embodiment detects whether the power switch device is short-circuited through a detection module, and outputs a first voltage signal when the power switch device is normally turned on, and outputs a second voltage signal when the power switch device is short-circuited; the protection module has an input end connected to the detection module and an output end connected to the driver chip of the power switch device, and is used to block the drive signal of the driver chip after the detection module outputs the second voltage, so that the power switch device is turned off. This embodiment is suitable for ordinary driver chips and can save costs. At the same time, the combination of the detection module and the protection module can avoid false triggering and improve the accuracy of short-circuit protection.

[0049] Example 2

[0050] This embodiment provides another short circuit protection circuit. Figure 3 FIG. 1 is a structural diagram of a short-circuit protection circuit according to another embodiment of the present invention. In order to realize the fault detection of IGBT, as shown in FIG. Figure 3As shown, the above-mentioned detection module 1 includes: a detection capacitor C1, a first end of the detection capacitor C1 is connected to the input end of the protection module 2, and a second end of the detection capacitor C1 is grounded; it also includes a charging unit 11 for charging the detection capacitor C1, a first end of the charging unit 11 is connected to the drain D of the IGBT, and a second end of the charging unit 11 is connected between the detection capacitor C1 and the input end of the protection module 2; the charging unit 11 includes a first switch Q1, and the first switch Q1 is used to control whether the charging unit charges the detection capacitor C1 by itself on and off.

[0051] Specifically, the charging unit 11 also includes: a first resistor R1 and a second resistor R2, the first end of the first resistor R1 is connected to the drain D of the IGBT, the second end of the first resistor R1 is connected to the first end of the second resistor R2 through the collector and emitter of the first switch in sequence, and the second end of the second resistor R2 is connected between the detection capacitor C1 and the input end of the protection module 2.

[0052] In order to control the on-state of the first switch Q1 according to the on-off control of the IGBT, the detection module 1 also includes a voltage divider unit 12, a first end of the voltage divider unit 12 is connected between the gate G of the IGBT and the driving resistor Rg, a second end thereof is connected to the emitter of the first switch, and a third end thereof is connected to the base of the first switch, and the voltage divider unit 12 is used to control the on-off of the first switch Q1 according to the gate G voltage of the IGBT.

[0053] In a specific implementation, the voltage dividing unit 12 may include: a third resistor R3 and a fourth resistor R4, wherein a first end of the third resistor R3 is connected between the gate G of the IGBT and the driving resistor Rg, a second end is connected to a first end of the fourth resistor R4, and a second end of the fourth resistor R4 is connected to the emitter of the first switch Q1 and between the second resistor R2; and a line between the third resistor R3 and the fourth resistor R4 is connected to the base of the first switch Q1. When the IGBT is turned on, the gate G voltage is relatively high, and a high voltage is output between the third resistor R3 and the fourth resistor R4, driving the first switch Q1 to be turned on, thereby turning on the charging unit 11 to charge the detection capacitor C1. If the first switch Q1 is in a normal on state, the capacitor C1 will no longer be charged after the voltage is equal to the saturation voltage of the IGBT. If the first switch Q1 is in a short-circuit state, the capacitor C1 will be further charged, and the output voltage of the detection module 1 will further increase, triggering the protection module 2 to start the short-circuit protection. When the IGBT is turned off, the gate G voltage is relatively low, and a low voltage is output between the third resistor R3 and the fourth resistor R4, controlling the first switch Q1 to be turned off, thereby turning off the charging unit 11 and stopping charging the detection capacitor C1.

[0054] The second resistor R2, the third resistor R3 and the fourth resistor R4 are also used to release the charge of the detection capacitor C1. After the IGBT is turned off, the first end of the detection capacitor C1, the second resistor R2, the fourth resistor R4, the third resistor R3, the driving resistor Rg, the output pin Vo of the driving chip U, the low level pin VEE of the driving chip U, and the second end of the detection capacitor C1 form a loop to release the charge of the detection capacitor C1.

[0055] Due to the presence of capacitors inside the IGBT, when the IGBT is turned off, the first switch Q1 continues to be turned on for a period of time. At this time, if the voltage at the first end of the first resistor R1 is high, the capacitor C1 will be further charged, and the output voltage of the detection module 1 will be further increased, which will erroneously trigger the protection module to start the short-circuit protection. In order to avoid the above situation, it is necessary to control the voltage of the emitter of the first switch Q1. Therefore, the above detection module 1 also includes: a clamping element D1, a first end of which is connected to the emitter of the first switch Q1, and the other end is connected to the high-level pin VCC of the driver chip. In this embodiment, the clamping element D1 is a diode, the anode of the diode is connected to the emitter of the first switch Q1, and the cathode is connected to the high-level pin VCC of the driver chip. The voltage of the emitter of the first switch Q1 is controlled at a certain value by the diode to avoid erroneous triggering of the short-circuit protection after the IGBT is turned off. In this embodiment, the first switch Q1 is an NPN transistor.

[0056] In order to trigger the short-circuit protection after the IGBT is short-circuited, and not trigger the short-circuit protection when the IGBT is normally turned on, the above-mentioned protection module 2 includes: a comparator A, the first input terminal + (non-inverting input terminal) of the comparator A is connected to the output terminal of the detection module 1 (i.e., the first terminal of the detection capacitor C1), the second input terminal - (inverting input terminal) of the comparator A is input with the reference voltage Vref, the output terminal of the comparator A is connected to the base of the second switch Q2 through the fifth resistor R5, and the first input terminal + of the comparator A is the input terminal of the protection module 2; the collector of the second switch Q2 is connected to the external voltage V1 through the sixth resistor R6, and the emitter is grounded; the line between the collector of the second switch Q2 and the sixth resistor R6 is connected to the high-level pin VCC of the driver chip U, and the sixth resistor R6 is used for current limiting. In order to provide a working voltage for the comparator A, the positive power supply of the comparator A is connected to the high-level pin VCC of the driver chip U, and the negative power supply is grounded. In this embodiment, the second switch Q2 is an NPN transistor.

[0057] By setting a suitable voltage-dividing resistor, the value of the reference voltage Vref is made higher than the saturation voltage of the IGBT and lower than the output voltage of the detection module 1 when the IGBT is short-circuited. When the IGBT is normally turned on, the maximum value of the voltage at the first terminal of the detection capacitor C1 will not exceed the saturation voltage of the IGBT, that is, the voltage at the non-inverting input terminal of the comparator A is less than the reference voltage Vref input at the inverting input terminal, the comparator A outputs a low voltage, the second switch Q2 is not turned on, the high-level pin VCC of the driver chip U inputs a high-level signal, and the driver chip U controls the on and off of the IGBT according to the input PWM signal; when the IGBT is short-circuited, the drain voltage of the IGBT increases, the detection capacitor C1 is continuously charged, the voltage at the first terminal of the detection capacitor C1 continues to increase, the non-inverting input terminal of the comparator A exceeds the reference voltage Vref input at the inverting input terminal of the comparator A, the comparator A outputs a high voltage, the second switch Q2 is turned on, the high-level pin VCC of the driver chip U is grounded, thereby inputting a low-level signal, and the drive signal of the driver chip U is blocked, that is, no matter whether the input PWM signal is high or low, the driver chip U outputs a low level, thereby controlling the IGBT to turn off.

[0058] In order to provide a suitable reference voltage Vref, the short-circuit protection circuit further includes: a reference voltage source 3, the first end of the reference voltage source 3 is connected to the high voltage level pin VCC of the driver chip U, the second end thereof is grounded, and the third end thereof is connected to the second input terminal - of the comparator A, and the reference voltage source is used to output the reference voltage Vref to the second input terminal of the comparator. Specifically, the reference voltage source 3 includes: an eighth resistor R8 and a ninth resistor R9, the first end of the eighth resistor R8 is connected to the high voltage level pin VCC of the driver chip U, the second end thereof is connected to the first end of the ninth resistor R9, the second end of the ninth resistor R9 is grounded, and the line between the eighth resistor R8 and the ninth resistor R9 is connected to the second input terminal of the comparator A. The voltage output from the high voltage level pin VCC is divided by the eighth resistor R8 and the ninth resistor R9 to obtain the reference voltage Vref, and the required reference voltage Vref can be obtained by designing the resistance values ​​of the eighth resistor R8 and the ninth resistor R9.

[0059] In actual application, the output voltage of comparator A may fluctuate, causing the base voltage of the second switch Q2 to increase and falsely trigger the short-circuit protection. In order to avoid the above situation, the protection module 2 also includes: a seventh resistor R7, the first end of the seventh resistor R7 is connected to the collector of the second switch Q2, and the second end is connected to the base of the second switch Q2, which is used to keep the base voltage of the second switch stable and avoid false triggering.

[0060] According to the above, due to the presence of capacitors inside the IGBT, after the driver chip U outputs a low-level signal, the IGBT cannot be turned off in time, which may cause the short-circuit protection to be triggered by mistake. In order to release the electric quantity of the capacitor inside the IGBT as soon as possible, the above-mentioned short-circuit protection circuit also includes: a third switch Q3, the base of the third switch Q3 is connected to the output pin Vo of the driver chip and the driving resistor Rg through the tenth resistor R10, the emitter is connected to the gate G of the IGBT, and the collector is grounded. The third switch Q3 is turned on after the driver chip U outputs a low-level signal, and the electric quantity of the capacitor between the gate and the source of the IGBT is released to avoid the short-circuit protection from being triggered by mistake. In this embodiment, the third switch Q3 is a PNP-type triode. At the same time, the first end of the detection capacitor C1, the second resistor R2, the fourth resistor R4, the third resistor R3, the third switch Q3, the low-level pin VEE of the driver chip U, and the second end of the detection capacitor C1 also form a loop to release the electric quantity of the detection capacitor C1.

[0061] Example 3

[0062] This embodiment provides another short circuit protection circuit. The structure of the short circuit protection circuit of this embodiment is as mentioned above. Figure 3 As shown in the figure, the short-circuit protection circuit mainly includes three parts: a detection module 1, a protection module 2 and a reference voltage source 3, wherein the detection module includes a detection capacitor C1, a first resistor R1, a first switch Q1, a second resistor R2, a clamping diode D1, a third resistor, and a fourth resistor; the protection module includes an operational amplifier comparator A, a second switch Q2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7; the reference voltage source 3 includes an eighth resistor R8 and a third resistor R9.

[0063] The driving circuit includes a driving chip U and a driving resistor Rg. The driving chip U is a common driving IC.

[0064] When the drive circuit operates normally, under the stimulation of the PWM pulse input by the driver chip U, the output pin of the driver chip U can synchronously output the drive signal. Under normal circumstances, the drive signal is divided into two states: high level and low level. When the drive signal is high level, the output current flows through the drive resistor Rg to charge the internal capacitor of the IGBT, and the IGBT begins to conduct slowly. The voltage V between the drain D and the source S DSThe voltage keeps decreasing. At the same time, as the potential of the gate G of the IGBT increases, under the voltage-dividing effect of the third resistor R3 and the fourth resistor R4, the PN junction between the base and the emitter of the first switch Q1 can be forward-biased turned on, and current flows between the base and the emitter, and the detection capacitor C1 is charged through the second resistor R2 until the saturation voltage drop Vce(sat) of the IGBT is reached. When the drive signal is at a low level, the base potential of the first switch Q1 cannot maintain the PN junction conduction, and at this time, the collector and the emitter of the first switch Q1 are disconnected, and current cannot flow. At the same time, the base and emitter of the third switch Q3 are forward-biased turned on, and current can flow between the collector and the emitter, which can discharge the internal capacitance of the IGBT on the one hand, and on the other hand, the detection capacitor C1 can be discharged to zero potential through the second resistor R2, the fourth resistor R4, the third resistor R3, and the third switch Q3.

[0065] The eighth resistor R7 and the ninth resistor R9 can provide a reference voltage Vref when the voltage VCC is powered on (the value of the reference voltage Vref needs to be calculated in combination with the characteristics of the IGBT itself, generally 6.5V). Under normal circumstances, the reference voltage Vref> the voltage across the first capacitor V C1 , at this time, comparator A outputs a low voltage (power supply negative, when using a single power supply, the voltage is 0). When the IGBT is short-circuited, the drain voltage will begin to rise, causing the detection capacitor C1 to be further charged. When the voltage V C1 >When the reference voltage Vref is on, the comparator A outputs a high voltage (power supply is positive), and the base and emitter of the second switch Q2 are turned on through the fifth resistor R5. At this time, the collector-emitter of the second switch Q1 is saturated and turned on, and the collector potential is clamped to the saturation voltage drop of the transistor (about 0.3-0.6V). The driver chip U is powered off and does not work at this moment. The seventh resistor R7 is used to set the working point of the transistor, and the sixth resistor R6 is used to limit the current. The resistance values ​​of the seventh resistor R7 and the sixth resistor R6 can be selected according to actual needs.

[0066] This embodiment provides a novel IGBT short-circuit protection circuit with a simple structure and low cost, which avoids the risk of false triggering of short-circuit protection caused by high-voltage diodes in traditional IGBT short-circuit circuits.

[0067] Example 4

[0068] This embodiment provides an electrical device, including an IGBT and a driver chip, and also includes the short-circuit protection circuit in the above embodiment, which is used to improve the accuracy of the short-circuit protection of the IGBT, thereby improving the reliability of the entire electrical device. In this embodiment, the above electrical device includes at least one of the following: an air conditioner, a washing machine, a refrigerator, a water heater, a fan, a dryer, an air purifier, a water purifier, and a pure water machine.

[0069] The circuit embodiments described above are merely illustrative, wherein the modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, i.e., they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A short circuit protection circuit, applied to a power switch device, characterized in that: The circuit comprises: A detection module, wherein the first input end thereof is connected to the gate of the power switch device, and is used to control whether the power switch device is powered on according to the on-off of the power switch device, and the second input end thereof is connected to the drain of the power switch device, and is used to detect whether the power switch device is short-circuited, and outputs a first voltage signal when the power switch device is normally turned on, and outputs a second voltage signal when the power switch device is short-circuited; the detection module comprises: a detection capacitor, wherein the first end thereof is connected to the input end of the protection module, and the second end thereof is grounded; a charging unit, wherein the first end thereof is connected to the drain of the power switch device, and the second end thereof is connected between the detection capacitor and the input end of the protection module; the charging unit comprises a first switch, and is used to control whether the charging unit charges the detection capacitor by turning on and off itself; a voltage dividing unit, wherein the first end thereof is connected between the gate of the power switch device and the driving resistor, the second end thereof is connected to the emitter of the first switch, and the third end thereof is connected to the base of the first switch, and the voltage dividing unit is used to control the on-off of the first switch according to the gate voltage of the power switch device; The protection module has an input end connected to the detection module and an output end connected to the driver chip of the power switch device, and is used to block the drive signal of the driver chip after the detection module outputs the second voltage signal to turn off the power switch device.

2. The circuit according to claim 1, characterized in that The charging unit further includes: A first resistor and a second resistor, wherein the first end of the first resistor is connected to the drain of the power switch device, the second end is connected to the first end of the second resistor through the collector and emitter of the first switch in sequence, and the second end of the second resistor is connected between the detection capacitor and the input end of the protection module.

3. The circuit according to claim 2, characterized in that The voltage dividing unit comprises: A third resistor and a fourth resistor, wherein the first end of the third resistor is connected between the gate of the power switching device and the driving resistor, the second end is connected to the first end of the fourth resistor, and the second end of the fourth resistor is connected between the emitter of the first switch and the second resistor; the line between the third resistor and the fourth resistor is connected to the base of the first switch.

4. The circuit according to claim 3, characterized in that The detection module also includes: A clamping element, a first end of which is connected to the emitter of the first switch, and the other end of which is connected to the high level pin of the driving chip.

5. The circuit according to claim 1, characterized in that The protection module comprises: A comparator, wherein a first input terminal of the comparator is connected to the output terminal of the detection module, a second input terminal of the comparator is input with a reference voltage, and an output terminal of the comparator is connected to the base of the second switch via a fifth resistor, and the first input terminal of the comparator is the input terminal of the protection module; The collector of the second switch is connected to an external voltage through a sixth resistor, and the emitter of the second switch is grounded. The line between the collector of the second switch and the sixth resistor is connected to a high level pin of the driving chip.

6. The circuit according to claim 5, characterized in that The protection module also includes: A seventh resistor, a first end of which is connected to the collector of the second switch, and a second end of which is connected to the base of the second switch, is used to keep the base voltage of the second switch stable.

7. The circuit according to claim 5, characterized in that The circuit further comprises: A reference voltage source has a first end connected to the high voltage level pin of the driver chip, a second end connected to the ground, and a third end connected to the second input end of the comparator. The reference voltage source is used to output a reference voltage to the second input end of the comparator.

8. The circuit according to claim 7, characterized in that The reference voltage source comprises: An eighth resistor and a ninth resistor, wherein the first end of the eighth resistor is connected to the high voltage level pin of the driving chip, the second end is connected to the first end of the ninth resistor, the second end of the ninth resistor is grounded, and the line between the eighth resistor and the ninth resistor is connected to the second input terminal of the comparator.

9. The circuit according to claim 1, characterized in that The circuit further comprises: The third switch has a base connected between the output pin of the driving chip and the driving resistor through a tenth resistor, an emitter connected to the gate of the power switch device, and a collector grounded.

10. An electrical device, comprising a power switch device and a driver chip, characterized in that: The electrical device further comprises a short-circuit protection circuit as claimed in any one of claims 1 to 9.

11. The electrical device according to claim 10, characterized in that: The electrical equipment includes at least one of the following: Air conditioners, washing machines, refrigerators, water heaters, fans, dryers, air purifiers, water purifiers, and water purifiers.

Images