CN112271703A - A short circuit protection circuit and electrical equipment - Google Patents
A short circuit protection circuit and electrical equipment Download PDFInfo
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- CN112271703A CN112271703A CN202011211476.1A CN202011211476A CN112271703A CN 112271703 A CN112271703 A CN 112271703A CN 202011211476 A CN202011211476 A CN 202011211476A CN 112271703 A CN112271703 A CN 112271703A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/20—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electronic equipment
- H02H7/205—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electronic equipment for controlled semi-conductors which are not included in a specific circuit arrangement
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
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Abstract
本发明公开一种短路保护电路及电器设备。其中，该电路包括：检测模块，其第一输入端连接所述功率开关器件的栅极，用于根据所述功率开关器件的通断控制自身是否通电，其第二输入端连接所述功率开关器件的漏极，用于检测所述功率开关器件是否短路，在所述功率开关器件正常导通时，输出第一电压信号，在所述功率开关器件短路时，输出第二电压信号；保护模块，其输入端连接所述检测模块，输出端连接所述功率开关器件的驱动芯片，用于在所述检测模块输出第二电压信号后，封锁所述驱动芯片的驱动信号，使所述功率开关器件关断。通过本发明，能够节约成本，同时能够避免误触发，提高短路保护的准确性。
The invention discloses a short circuit protection circuit and electrical equipment. Wherein, the circuit includes: a detection module, the first input terminal of which is connected to the gate of the power switch device to control whether it is powered on according to the on-off state of the power switch device, and the second input terminal of which is connected to the power switch The drain of the device is used to detect whether the power switch device is short-circuited, when the power switch device is normally turned on, output a first voltage signal, and when the power switch device is short-circuited, output a second voltage signal; protection module , the input end is connected to the detection module, and the output end is connected to the drive chip of the power switch device, which is used to block the drive signal of the drive chip after the detection module outputs the second voltage signal, so that the power switch device shuts down. The invention can save cost, avoid false triggering, and improve the accuracy of short-circuit protection.
Description
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a short-circuit protection circuit and electrical equipment.
Background
A power switching device (e.g., an Insulated Gate Bipolar Transistor, IGBT) is a commonly used electronic device, and is widely used in products such as power supplies, household appliances, and air conditioners, and plays a key role. In a power electronic system, short circuits are divided into a type I short circuit (short circuit in bridge arms) and a type II short circuit (short circuit between bridge arms), wherein the type I short circuit mainly causes direct connection of upper and lower pipes of the same bridge arm due to hardware failure or software failure, and the type II short circuit causes direct connection between different bridge arms due to interphase short circuit or relative ground short circuit and the like. In the current technical solution, the class II short circuit generally performs overcurrent protection by monitoring the grid current through a current sensor. For the class I short circuit problem, a desaturation mechanism is generally utilized, a peripheral circuit is used to monitor the saturation voltage drop vce (sat) of the IGBT, fig. 1 is a peripheral circuit used in the prior art to implement short circuit protection, and the peripheral circuit is composed of a blanking capacitor, a high voltage diode, and a resistor. The scheme generally needs to use an integrated driving chip with an accessory desaturation detection function, so that the cost is high; meanwhile, because the high-voltage diode has relatively high junction capacitance, when the IGBT is switched on and switched off every time, displacement current generated by the diode is easy to interfere with other electronic devices, short-circuit protection false alarm is caused, and the problem of short-circuit protection accuracy is caused.
Aiming at the problems of high cost and low accuracy of short-circuit protection of a power switch device in the prior art, an effective solution is not provided at present.
Disclosure of Invention
The embodiment of the invention provides a short-circuit protection circuit and electrical equipment, and aims to solve the problems of high cost and low accuracy of short-circuit protection of a power switch device in the prior art.
In order to solve the above technical problem, the present invention provides a short-circuit protection circuit applied to a power switch device, wherein the short-circuit protection circuit includes:
the first input end of the detection module is connected with the grid electrode of the power switch device and used for controlling whether the detection module is electrified or not according to the on-off of the power switch device, and the second input end of the detection module is connected with the drain electrode of the power switch device and used for detecting whether the power switch device is short-circuited or not, outputting a first voltage signal when the power switch device is normally conducted, and outputting a second voltage signal when the power switch device is short-circuited;
and the input end of the protection module is connected with the detection module, the output end of the protection module is connected with the driving chip of the power switch device, and the protection module is used for blocking the driving signal of the driving chip to turn off the power switch device after the detection module outputs the second voltage signal.
Further, the detection module includes:
the first end of the detection capacitor is connected with the input end of the protection module, and the second end of the detection capacitor is grounded;
a first end of the charging unit is connected with the drain electrode of the power switch device, and a second end of the charging unit is connected between the detection capacitor and the input end of the protection module; the charging unit comprises a first switch and is used for controlling whether the charging unit charges the detection capacitor or not through the on-off of the charging unit;
and a first end of the voltage division unit is connected between the grid electrode of the power switch device and the driving resistor, a second end of the voltage division unit is connected to the emitter electrode of the first switch, a third end of the voltage division unit is connected with the base electrode of the first switch, and the voltage division unit is used for controlling the on-off of the first switch according to the grid electrode voltage of the power switch device.
Further, the charging unit further includes:
the first end of the first resistor is connected with the drain electrode of the power switch device, the second end of the first resistor is connected with the first end of the second resistor sequentially through the collector electrode and the emitter electrode of the first switch, and the second end of the second resistor is connected between the detection capacitor and the input end of the protection module.
Further, the voltage dividing unit includes:
a first end of the third resistor is connected between the grid electrode of the power switch device and the driving resistor, a second end of the third resistor is connected with a first end of the fourth resistor, and a second end of the fourth resistor is connected between the emitter electrode of the first switch and the second resistor; and a line between the third resistor and the fourth resistor is connected with the base electrode of the first switch.
Further, the detection module further comprises:
and a first end of the clamping element is connected with the emitter of the first switch, and the other end of the clamping element is connected with a high-level pin of the driving chip.
Further, the protection module includes:
a comparator, a first input end of which is connected with the output end of the detection module, a second input end of which inputs the reference voltage, and an output end of which is connected with a base electrode of the second switch through a fifth resistor, wherein the first input end of the comparator is the input end of the protection module;
and the collector of the second switch is connected with external voltage through a sixth resistor, the emitter of the second switch is grounded, and a line between the collector of the second switch and the sixth resistor is connected with a high-level pin of the driving chip.
Further, the protection module further comprises:
and a seventh resistor, a first end of which is connected with the collector of the second switch, and a second end of which is connected with the base of the second switch, for keeping the base voltage of the second switch stable.
Further, the circuit further comprises:
and a first end of the reference voltage source is connected with the high-voltage flat pin of the driving chip, a second end of the reference voltage source is grounded, a third end of the reference voltage source is connected with the second input end of the comparator, and the reference voltage source is used for outputting reference voltage to the second input end of the comparator.
Further, the reference voltage source includes:
the first end of the eighth resistor is connected with the high-voltage flat pin of the driving chip, the second end of the eighth resistor is connected with the first end of the ninth resistor, the second end of the ninth resistor is grounded, and a line between the eighth resistor and the ninth resistor is connected with the second input end of the comparator.
Further, the circuit further comprises:
and the base of the third switch is connected between the output pin of the driving chip and the driving resistor through a tenth resistor, the emitter of the third switch is connected with the grid of the power switch device, and the collector of the third switch is grounded.
The invention also provides electrical equipment which comprises a power switch device and a driving chip and is characterized by further comprising the short-circuit protection circuit.
Further, the electrical device comprises at least one of:
air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.
By applying the technical scheme of the invention, whether the power switch device is short-circuited is detected through the detection module, when the power switch device is normally conducted, a first voltage signal is output, and when the power switch device is short-circuited, a second voltage signal is output; protection module, its input is connected detection module, the output is connected power switch device's driver chip is used for behind detection module output second voltage, blockade driver chip's drive signal makes power switch device turn-offs, and this scheme is applicable to ordinary driver chip, can practice thrift the cost, simultaneously, adopts detection module and protection module to combine, can avoid the spurious triggering, improves short-circuit protection's accuracy.
Drawings
FIG. 1 illustrates a peripheral circuit used in the prior art for short-circuit protection;
FIG. 2 is a block diagram of a short-circuit protection circuit according to an embodiment of the present invention;
fig. 3 is a block diagram of a short-circuit protection circuit according to another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
It should be understood that although the terms first, second, third, etc. may be used to describe the switches in embodiments of the present invention, the switches should not be limited to these terms. These terms are only used to distinguish between switches disposed in different positions. For example, a first switch may also be referred to as a second switch, and similarly, a second switch may also be referred to as a first switch, without departing from the scope of embodiments of the present invention.
The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.
It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in the article or device in which the element is included.
Alternative embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Example 1
The present embodiment provides a short-circuit protection circuit, which is applied to a power switch device, and fig. 2 is a structural diagram of the short-circuit protection circuit according to an embodiment of the present invention, wherein a driving circuit of the power switch device includes: the driving chip U comprises 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 with a grid G of a power switch device (in the embodiment, the ICBT is taken as an example), the low-level pin VEE is connected with a source S of the IGBT, when the PWM signal is at a high level, the output pin Vo is conducted with the high-level pin VCC to output a high-level signal to drive the IGBT to be conducted, and when the PWM signal is at a low level, the output pin Vo is conducted with the low-level pin VEE to output a low-level signal to control the IGBT to be turned off.
As shown in fig. 2, the short-circuit protection circuit includes: the detection module 1 is characterized in that a first input end of the detection module 1 is connected with a grid G of the IGBT and used for controlling whether the IGBT is electrified or not according to the on-off of the IGBT, a second input end of the detection module 1 is connected with a drain D of the IGBT and used for detecting whether the IGBT is short-circuited or not, a first voltage signal is output when the IGBT is normally conducted, and a second voltage signal is output when the IGBT is short-circuited;
When the IGBT is in a turn-off state, the detection module 1 is not electrified, when the IGBT is normally conducted, the detection module 1 is electrified, the maximum voltage value of the drain electrode D of the IGBT is detected to be the saturation voltage value of the IGBT, the protection circuit 2 is not triggered to work at the moment, the driving chip U normally outputs a high-level signal or a low-level signal according to the input PWM signal, when the IGBT is in a short circuit, the voltage of the drain electrode D can be increased to be 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, the driving signal of the driving chip U is blocked, the driving chip U is enabled to always output the low-level signal, and the.
The short-circuit protection circuit of the embodiment detects whether a power switch device is short-circuited through a detection module, outputs a first voltage signal when the power switch device is normally conducted, and outputs a second voltage signal when the power switch device is short-circuited; protection module, its input is connected detection module, the output is connected power switch device's driver chip is used for behind detection module output second voltage, blockade driver chip's drive signal makes power switch device cuts off, and this embodiment is applicable to ordinary driver chip, can practice thrift the cost, simultaneously, adopts detection module and protection module to combine, can avoid the spurious triggering, improves short-circuit protection's accuracy.
Example 2
In this embodiment, another short-circuit protection circuit is provided, and fig. 3 is a structural diagram of a short-circuit protection circuit according to another embodiment of the present invention, in order to implement fault detection of an IGBT, as shown in fig. 3, the detection module 1 includes: a first end of the detection capacitor C1 is connected with an input end of the protection module 2, and a second end of the detection capacitor C1 is grounded; the protection circuit also comprises a charging unit 11 for charging the detection capacitor C1, wherein a first end of the charging unit 11 is connected with 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 turning on and off itself.
Specifically, the charging unit 11 further includes: the first end of the first resistor R1 is connected with the drain D of the IGBT, the second end of the first resistor R1 is connected with the first end of the second resistor R2 through the collector and the 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.
In order to control the on state of the first switch Q1 according to the on/off of the IGBT, the detection module 1 further includes a voltage dividing unit 12, a first end of the voltage dividing 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, a third end thereof is connected to the base of the first switch, and the voltage dividing unit 12 is configured to control the on/off of the first switch Q1 according to the voltage of the gate G of the IGBT.
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 with a first end of the fourth resistor R4, and a second end of the fourth resistor R4 is connected between the emitter of the first switch Q1 and the second resistor R2; the 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 voltage of the gate G is high, a high voltage is output between the third resistor R3 and the fourth resistor R4, the first switch Q1 is driven to be turned on, the charging unit 11 is further turned on, and the detection capacitor C1 is charged, if the first switch Q1 is in a normal on state, the voltage of the capacitor C1 is equal to the saturation voltage of the IGBT, and then the charging will not be continued, if the first switch Q1 is in a short-circuit state, the capacitor C1 is further charged, the output voltage of the detection module 1 is further increased, and the protection module 2 is triggered to start short-circuit protection; when the IGBT is turned off, the voltage of the gate G is low, and a low voltage is output between the third resistor R3 and the fourth resistor R4, so as to control the first switch Q1 to turn off, and further turn off the charging unit 11, and stop charging the detection capacitor C1.
The second resistor R2, the third resistor R3, and the fourth resistor R4 are further configured to release the electric quantity of the detection capacitor C1, and 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 electric quantity of the detection capacitor C1.
Because there is a capacitor inside the IGBT, when the IGBT is turned off, the first switch Q1 still continues to be turned on for a period of time, and if the voltage at the first end of the first resistor R1 is high, the capacitor C1 is further charged, the output voltage of the detection module 1 further rises, and the protection module is triggered to start short-circuit protection by mistake, in order to avoid the above situation, it is necessary to control the voltage of the emitter of the first switch Q1, therefore, the detection module 1 further includes: the first end of the clamping element D1 is connected to the emitter of the first switch Q1, 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, the cathode of the diode is connected to the high-level pin VCC of the driver chip, and the voltage of the emitter of the first switch Q1 is controlled to a certain value by the diode, so as to avoid false triggering of short-circuit protection after the IGBT is turned off. In this embodiment, the first switch Q1 is an NPN transistor.
In order to realize that short-circuit protection is triggered after the IGBT is short-circuited, and short-circuit protection is not triggered when the IGBT is normally turned on, the protection module 2 includes: a first input end (non-inverting input end) of the comparator a is connected with the output end (namely, the first end of the detection capacitor C1) of the detection module 1, a second input end- (inverting input end) of the comparator a inputs the reference voltage Vref, the output end of the comparator a is connected with the base of the second switch Q2 through a fifth resistor R5, and the first input end + of the comparator a is the input end of the protection module 2; the collector of the second switch Q2 is connected with the external voltage V1 through a 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 the operating voltage for the comparator a, the positive power supply of the comparator a is connected to the high-level pin VCC of the driving chip U, and the negative power supply is grounded, in this embodiment, the second switch Q2 is an NPN type transistor.
By setting a proper voltage dividing resistor, the value of the reference voltage Vref is 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 conducted, the maximum value of the voltage of the first end of the detection capacitor C1 does not exceed the saturation voltage of the IGBT, namely the voltage of the non-inverting input end of the comparator A is smaller than the reference voltage Vref input by the inverting input end, the comparator A outputs low voltage, the second switch Q2 is not conducted, a high-level pin VCC of the driving chip U inputs a high-level signal, and the driving chip U controls the on-off of the IGBT according to the input PWM signal; when the IGBT is in short circuit, the drain voltage of the IGBT is increased, the detection capacitor C1 is continuously charged, the voltage of the first end of the detection capacitor C1 is continuously increased, the non-inverting input end of the comparator A exceeds the reference voltage Vref input by the inverting input end of the comparator A, the comparator A outputs high voltage, the second switch Q2 is turned on, the high-level pin VCC of the driving chip U is grounded, so that a low-level signal is input, the driving signal of the driving chip U is blocked, namely, no matter whether the input PWM signal is high level or low level, the driving chip U outputs low level, so that the IGBT is controlled to be turned off.
In order to provide a suitable reference voltage Vref, the short-circuit protection circuit further includes: and a first end of the reference voltage source 3 is connected with a high-voltage flat pin VCC of the driving chip U, a second end of the reference voltage source 3 is grounded, a third end of the reference voltage source 3 is connected with a second input end-of the comparator A, and the reference voltage source is used for outputting a reference voltage Vref to the second input end of the comparator. Specifically, the reference voltage source 3 includes: eighth resistance R8 and ninth resistance R9, the first end of eighth resistance R8 connects the high voltage flat pin VCC of driver chip U, and the first end of second end connection ninth resistance R9, the second end ground of ninth resistance R9, the second input of comparator A is connected to the circuit between eighth resistance R8 and ninth resistance R9. The voltage output by the high-voltage flat pin VCC is divided through 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.
In practical applications, the output voltage of the comparator a may fluctuate, which may cause the base voltage of the second switch Q2 to rise, and trigger the short-circuit protection by mistake, and in order to avoid the above situation, the protection module 2 further includes: and a first end of the seventh resistor R7 and a second end of the seventh resistor R7 are connected with the collector of the second switch Q2, and a base electrode of the second switch Q2, so that the base electrode voltage of the second switch is kept stable, and false triggering is avoided.
According to the above, since there is a capacitor inside the IGBT, after the driving chip U outputs a low level signal, the IGBT cannot be turned off in time, which may cause a false trigger of the short-circuit protection, and in order to release the electric quantity of the capacitor inside the IGBT as soon as possible, the short-circuit protection circuit further includes: and a third switch Q3, wherein the base of the third switch Q3 is connected between the output pin Vo of the driving chip and the driving resistor Rg through a tenth resistor R10, the emitter is connected with the grid G of the IGBT, and the collector is grounded. The third switch Q3 is turned on after the driving chip U outputs a low-level signal, electric quantity of a capacitor between the grid electrode and the source electrode of the IGBT is released, and short-circuit protection is prevented from being triggered by mistake. In this embodiment, the third switch Q3 is a PNP type triode, and 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 driving 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.
Example 3
The present embodiment provides another short-circuit protection circuit, the structure of the short-circuit protection circuit of the present embodiment is as shown in fig. 3 mentioned above, the short-circuit protection circuit mainly includes three parts, namely, 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 comprises 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 fourth resistor R9.
The driving circuit comprises a driving chip U and a driving resistor Rg, wherein the driving chip U is a common driving IC.
When the driving circuit normally operates, the output pin of the driving chip U can synchronously output driving signals under the excitation of the PWM pulse input by the driving chip U. Normally, the driving signal is divided into two states of high level and low level: when the driving signal is at high level, the output current flows through the driving resistor Rg to charge the internal capacitor of the IGBTElectrically, the IGBT starts to conduct slowly, the voltage V between the drain D and the source SDSThe voltage is continuously reduced. Meanwhile, as the potential of the gate G of the IGBT increases, under the voltage division 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 is turned on in a forward biased manner, a current flows between the base and the emitter, and the detection capacitor C1 is charged through the second resistor R2 until the saturation voltage vce (sat) of the IGBT is reached. When the driving signal is low, the base potential of the first switch Q1 cannot maintain the PN junction on, and at this time, the collector and emitter of the first switch Q1 are disconnected, and current cannot flow. Meanwhile, the base emitter of the third switch Q3 is forward biased and turned on, and a current can flow between the collector and the emitter, so that on one hand, the internal capacitance of the IGBT can be discharged, 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.
The eighth resistor R7 and the ninth resistor R9 can provide a reference voltage Vref (the value of the reference voltage Vref needs to be calculated by combining the characteristics of the IGBT and is generally 6.5V) when the voltage VCC is electrified, and the reference voltage Vref is normally set>Voltage V across the first capacitorC1At this time, the comparator a outputs a low voltage (when the power supply is negative, and when the power supply is a single power supply, the voltage is 0). When the short circuit of the IGBT occurs, the drain voltage will start to rise, so that the detection capacitor C1 is further charged, and when the voltage V is applied across the detection capacitor C1C1>When the reference voltage is Vref, the comparator A outputs high voltage (positive power supply), the base electrode and the emitter electrode of the second switch Q2 are conducted through the fifth resistor R5, the collector electrode-emitter electrode of the second switch Q1 is conducted in a saturation mode at the moment, the collector electrode potential is clamped to the saturation voltage drop (about 0.3-0.6V) of the triode, the driving chip U is powered off and does not work at the moment, the seventh resistor R7 is used for setting the working point of the triode, the sixth resistor R6 is used for limiting current, and the resistance values of the seventh resistor R7 and the sixth resistor R6 can be selected according to actual needs.
The embodiment provides a simple structure, low cost's novel IGBT short-circuit protection circuit, has avoided traditional IGBT short-circuit to arouse the risk that short-circuit protection triggers by mistake because of high-voltage diode.
Example 4
This embodiment provides an electrical equipment, including IGBT and driver chip, still include short-circuit protection circuit in the above-mentioned embodiment for promote IGBT's short-circuit protection accuracy, and then promote whole electrical equipment's reliability. In this embodiment, the electrical equipment at least includes one of the following: air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.
The above-described circuit embodiments are merely illustrative, wherein the modules described as separate parts may or may not be physically separate, and the parts shown as modules may or may not be physical modules, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; 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; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (12)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011211476.1A CN112271703B (en) | 2020-11-03 | A short circuit protection circuit and electrical equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011211476.1A CN112271703B (en) | 2020-11-03 | A short circuit protection circuit and electrical equipment |
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| Publication Number | Publication Date |
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| CN112271703A true CN112271703A (en) | 2021-01-26 |
| CN112271703B CN112271703B (en) | 2025-04-11 |
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