CN111817257A - Low-voltage power failure protection circuit and low-voltage power failure protection device - Google Patents

Abstract

The invention provides a low-voltage power supply power-down protection circuit and a low-voltage power supply power-down protection device, wherein the low-voltage power supply power-down protection circuit comprises a first power supply input end communicated with a first low-voltage power supply, a second power supply input end communicated with a second low-voltage power supply, a comparison switch circuit and an execution circuit; the first comparison end of the comparison switch circuit is connected with the first power input end, the second comparison end of the comparison switch circuit is connected with the second power input end, the power input end of the comparison switch circuit is communicated with the first low-voltage power supply, and the power output end of the comparison switch circuit is connected with the power end of the execution circuit. The technical scheme of the invention can solve the technical problem that the insulated gate bipolar transistor is damaged due to the fact that the electric drive system executes active short-circuit operation when the low-voltage power supply is powered down.

Description

Low-voltage power failure protection circuit and low-voltage power failure protection device

technical field

The invention relates to the technical field of electric vehicles, in particular to a low-voltage power failure protection circuit and a low-voltage power failure protection device.

Background technique

With the popularity of electric vehicles, the safety of electric vehicles has been paid more and more attention. Specifically, when a safety fault occurs in the electric drive system, such as a fault that violates the torque safety, the electric drive system should enter a safe state, that is, ASC (active short circuit, active short circuit) or Freewheeling. Among them, the path for the electric drive system to enter a safe state is usually divided into three levels: torque control level (software category), torque monitoring level (software category), and MCU (Micro Control Unit) monitoring level (hardware category). The MCU monitoring level is completely triggered by hardware and is not controlled by software to ensure that ASC operations can still be performed in the event of MCU failure.

During the operation of the electric drive system, once the low-voltage power supply is powered off, the MCU monitoring level will trigger the execution of ASC. At this time, due to the power-off of the low-voltage power supply, the output voltage of the driving power supply drops, resulting in insufficient driving voltage. ASC operation will cause damage to IGBT (Insulated Gate Bipolar Transistor, Insulated Gate Bipolar Transistor). In order to prevent damage to IGBT when the electric drive system performs ASC operation in this case, the drive power supply is often backed up, and an additional drive power supply is used from high voltage Power battery to take power. However, adding a backup power source will increase the cost of the electric drive system and increase the PCB area.

SUMMARY OF THE INVENTION

The present invention provides a low-voltage power supply power failure protection circuit and a low-voltage power supply power failure protection device, aiming at solving the technical problem that the electric drive system performs an active short-circuit operation when the low-voltage power supply is powered down, causing damage to the insulated gate bipolar transistor.

In order to achieve the above object, the present invention provides a low-voltage power failure protection circuit, the low-voltage power failure protection circuit includes a first power input terminal connected to the first low-voltage power supply, and a second power input terminal connected to the second low-voltage power supply. terminal, comparison switch circuit and execution circuit;

The first comparison terminal of the comparison switch circuit is connected to the first power supply input terminal, the second comparison terminal of the comparison switch circuit is connected to the second power supply input terminal, and the power supply input terminal of the comparison switch circuit is connected to the second power supply input terminal. the first low-voltage power supply is connected, and the power output terminal of the comparison switch circuit is connected to the power supply terminal of the execution circuit;

The comparison switch circuit is configured to disconnect the input power supply of the execution circuit according to a predetermined manner when the second low-voltage power supply is powered off, so that the execution circuit stops performing the active short-circuit operation.

Optionally, a power input terminal of the comparison switch circuit is connected to the first power input terminal.

Optionally, the comparison switch circuit includes a comparison circuit and a switch circuit;

The positive input terminal of the comparison circuit is the first comparison terminal of the comparison switch circuit, the negative input terminal of the comparison circuit is the second comparison terminal of the comparison switch circuit, and the output terminal of the comparison circuit is the same as the comparison circuit. The controlled end of the switch circuit is connected;

The power input terminal of the switch circuit is the power input terminal of the comparison switch circuit, and the power output terminal of the switch circuit is the power output terminal of the comparison switch circuit.

Optionally, the switch circuit includes a first resistor, a second resistor and a first transistor;

The first end of the first resistor is connected to the first power input end, the second end of the first resistor is connected to the first end of the second resistor, and the first end of the second resistor is the controlled end of the switch circuit, the second end of the second resistor is connected to the controlled end of the first transistor;

The input end of the first transistor is the power input end of the switch circuit, and the output end of the first transistor is the power output end of the switch circuit.

Optionally, the low-voltage power failure protection circuit further includes a signal detection circuit and an execution signal input terminal;

The input end of the signal detection circuit is connected with the execution signal input end, and the output end of the signal detection circuit is connected with the signal input end of the execution circuit.

Optionally, the signal detection circuit includes a third power input terminal, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second capacitor and a second transistor;

The first end of the third resistor is the input end of the signal detection circuit, the second end of the third resistor is connected to the controlled end of the second transistor, and the second end of the third resistor is connected to the controlled end of the second transistor. The first end of the fourth resistor is connected, the second end of the third resistor is connected to the first end of the first capacitor; the second end of the fourth resistor, the output end of the second transistor and the second end of the first capacitor is grounded;

The first end of the fifth resistor is connected to the input end of the third power supply, the second end of the fifth resistor is the output end of the signal detection circuit, and the second end of the fifth resistor is connected to the output end of the signal detection circuit. the input end of the second transistor is connected;

The second end of the fifth resistor is connected to the first end of the second capacitor, and the second end of the second capacitor is grounded.

Optionally, the execution circuit includes a digital isolator and an active short-circuit execution circuit;

The power supply end of the digital isolator is the power supply end of the execution circuit, the signal input end of the digital isolator is the signal input end of the execution circuit, and the signal output end of the digital isolator is short-circuited with the active circuit The input terminals of the execution circuit are connected.

Optionally, the low-voltage power failure protection circuit further includes a voltage regulator circuit;

The input end of the voltage stabilization circuit is connected to the first low-voltage power supply, and the output end of the voltage stabilization circuit is connected to the input end of the first power supply.

Optionally, the voltage regulator circuit includes a sixth resistor, a voltage regulator diode and a third capacitor;

The first end of the sixth resistor is connected to the first low-voltage power supply, the second end of the sixth resistor is connected to the input end of the first power supply, and the second end of the sixth resistor is connected to the stabilizer. The cathode of the zener diode is connected to the first end of the third capacitor; the anode of the zener diode and the second end of the third capacitor are grounded.

Optionally, the low-voltage power failure protection circuit further includes an EMC filter circuit, an anti-reverse connection circuit and a filter circuit;

The input end of the EMC filter circuit is connected to the second low-voltage power supply, the output end of the EMC filter circuit is connected to the input end of the anti-reverse connection circuit, and the output end of the anti-reverse connection circuit is connected to the filter The input end of the circuit is connected, and the output end of the filter circuit is connected with the input end of the second power supply.

In order to achieve the above object, the present invention also provides a low-voltage power failure protection device, wherein the low-voltage power failure protection device includes the low-voltage power failure protection circuit described in any one of the above.

According to the technical solution of the present invention, the power failure of the battery of the electric vehicle will trigger the comparison switch circuit to turn off, and the power supply of the execution circuit is cut off by turning off the comparison switch circuit, so that the execution circuit does not perform the ASC operation, thereby avoiding the situation of insufficient driving voltage. The IGBT is damaged due to the ASC operation performed under the

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without creative efforts.

FIG. 1 is a structural block diagram of an embodiment of a low-voltage power supply power failure protection circuit according to the present invention;

FIG. 2 is a schematic diagram of a circuit structure of an embodiment of the comparison switch circuit in FIG. 1;

3 is a structural block diagram of another embodiment of a low-voltage power supply power-down protection circuit according to the present invention;

FIG. 4 is a schematic diagram of a circuit structure of an embodiment of the signal detection circuit in FIG. 3;

5 is a structural block diagram of an embodiment of the execution circuit in FIG. 3;

FIG. 6 is a structural block diagram of another embodiment of the low-voltage power supply power-down protection circuit of the present invention.

Description of reference numbers:

Vin1 first low voltage power supply Vin2 Second low voltage power supply V1 first power input V2 second power input V3 The third power input terminal IN Execute signal input 10 Compare switch circuit 20 executive circuit 30 Signal detection circuit 40 Regulator circuit 50 EMC filter circuit 60 Anti-reverse circuit 70 filter circuit R1～R7 The first resistor to the seventh resistor T Zener diode C1～C3 The first capacitor to the third capacitor Q1 first transistor Q2 second transistor 101 comparison circuit 102 switch circuit 201 digital isolator 202 Active short-circuit execution circuit

The realization, functional characteristics and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that if there are directional indications (such as up, down, left, right, front, back, etc.) involved in the embodiments of the present invention, the directional indications are only used to explain a certain posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly.

In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for the purpose of description, and should not be construed as indicating or implying Its relative importance or implicitly indicates the number of technical features indicated. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of such technical solutions does not exist. , is not within the scope of protection required by the present invention.

FIG. 1 is a structural block diagram of an embodiment of a low-voltage power supply power failure protection circuit according to the present invention.

Referring to FIG. 1 , the low-voltage power failure protection circuit includes a first power input terminal V1 in communication with the first low-voltage power supply Vin1, a second power supply input terminal V2 in communication with the second low-voltage power supply Vin2, a comparison switch circuit 10 and an execution circuit 30 ;

The first comparison terminal of the comparison switch circuit 10 is connected to the first power input terminal V1, the second comparison terminal of the comparison switch circuit 10 is connected to the second power input terminal V2, and the power input terminal of the comparison switch circuit 10 is connected to The first low-voltage power source Vin1 is connected, and the power output terminal of the comparison switch circuit 10 is connected to the power source terminal of the execution circuit 20 .

The comparison switch circuit 10 has two states of off and on, and has the following characteristics: when the voltage of the first comparison terminal of the comparison switch circuit 10 is greater than the voltage of the second comparison terminal of the comparison switch circuit 10, the comparison switch circuit 10 is turned off; When the voltage of the first comparison terminal of the switch circuit 10 is lower than the voltage of the second comparison terminal thereof, the comparison switch circuit 10 is turned on.

The execution circuit 20 is a hardware ASC (active short circuit) execution circuit, and is used to execute the ASC operation according to the execution signal input from the outside when the comparison switch circuit 10 is turned on.

The voltage input from the second power input terminal V2 is provided by the positive battery (KL30) in the electric vehicle, that is, the second low-voltage power Vin2 via an EMC filter circuit 50 , an anti-reverse connection circuit 60 and a filter circuit 70 .

It should be noted that, in this embodiment, the first low-voltage power supply Vin1 connected to the first power supply input terminal V1 is taken from the weak-current side power supply that has nothing to do with the hardware ASC triggering and has a relatively slow power-down speed. For example, set the hardware ASC The trigger signal is provided by SBC (single board computer, single-board computer), and the second low-voltage power supply Vin2 is also provided by SBC. Then, the first low-voltage power supply that is connected to the first power input terminal V1 and supplies power to the first power input terminal V1 Vin1 selects a low-voltage power source not generated by SBC, and selects the low-voltage power source with the slowest power-down speed among the low-voltage power sources not generated by SBC; that is, the first low-voltage power supply that supplies power to the first power input terminal V1 does not come from the low-voltage power source generated by SBC. choose. In this way, in the case of non-electric vehicle battery power failure, since the first low-voltage power supply Vin1 connected to the first power supply input terminal V1 has nothing to do with the hardware ASC triggering, the common cause failure can be avoided, so that the execution circuit 20 can operate normally. Perform an ASC operation.

Optionally, in a specific embodiment, the first power input terminal V1 can be directly connected to the power input terminal of the comparison switch circuit 10 , so that the voltage input by the first power input terminal V1 serves as the reference voltage of the comparison switch circuit 10 . , is also used to power the execution circuit 20 . Of course, the power input end of the comparison switch circuit 10 can also be communicated or connected with other low-voltage power sources, wherein the other low-voltage power sources described here are selected from the weak-side power sources that have nothing to do with hardware ASC triggering and have a relatively slow power-down speed.

The specific working principle is as follows: when the KL30 (positive electrode of the battery) of the electric vehicle is in a non-power-off state, that is, when the second low-voltage power supply Vin2 is not powered off, the input voltage of the second power supply input terminal V2 is normal. Specifically, the second power supply The voltage input by the input terminal V2 is greater than the voltage input by the first power input terminal V1, and the comparison switch circuit 10 is turned on. When the comparison switch circuit 10 is in an on state, the first power input terminal V1 supplies power to the execution circuit 20 through the turned-on comparison switch circuit 10. In this case, if an execution signal is input to the execution circuit 20 from the outside, the execution circuit 20 will To perform the ASC operation, if no external execution signal is input to the execution circuit 20, the execution circuit 20 does not perform the ASC operation.

When the KL30 of the electric vehicle is powered off, the voltage input by the second power input terminal V2 will gradually decrease. When the voltage input by the second power input terminal V2 is lower than the voltage input by the first power input terminal V1, the driving voltage at this time is indicated. Insufficient, the ASC operation will damage the IGBT when the driving voltage is insufficient. At this time, the comparison switch circuit 10 is switched from the on state to the off state. When the comparison switch circuit 20 is turned off, the electrical connection between the first power input terminal V1 and the execution circuit 20 is disconnected, and the execution circuit 20 is powered off. After the execution circuit 20 is powered off, the execution circuit 20 does not execute the ASC operation regardless of whether an execution signal is input to the execution circuit 20 from the outside. In this way, the execution circuit 20 does not perform the ASC operation by cutting off the power supply of the execution circuit 20 when the KL30 is powered off, so that the ASC operation can be prevented from being performed under the condition of insufficient driving voltage due to the power failure of the KL30, thereby causing the IGBT to be damaged. And this arrangement does not require a backup drive power supply, thereby saving the cost of the electric vehicle.

According to the technical solution of the present invention, the power failure of the battery of the electric vehicle will trigger the comparison switch circuit 10 to be turned off, and the power supply of the execution circuit 20 will be cut off by turning off the comparison switch circuit 10, so that the execution circuit 20 cannot perform the ASC operation, thereby avoiding the need for driving The IGBT is damaged when the ASC operation is performed under the condition of insufficient voltage, and the backup driving power supply is not required, which can reduce the cost of the electric vehicle and reduce the complexity of the PCB design of the electric vehicle.

Optionally, referring to FIG. 2 , in an embodiment, the comparison switch circuit 10 includes a comparison circuit 101 and a switch circuit 102;

The positive input terminal of the comparison circuit 101 is the first comparison terminal of the comparison switch circuit 10 , the negative input terminal of the comparison circuit 101 is the second comparison terminal of the comparison switch circuit 10 , and the output terminal of the comparison circuit 101 is connected to the switch circuit The power input terminal of the switch circuit 102 is the power input terminal of the comparison switch circuit 10 , and the power output terminal of the switch circuit 102 is the power output terminal of the comparison switch circuit 10 .

The comparison circuit 101 can be selected as a comparator, and the comparison circuit 101 has the following characteristics: when the voltage of the positive input terminal of the comparison circuit 101 is greater than the voltage of the negative input terminal of the comparison circuit 101, the comparison circuit 101 outputs a high level; When the voltage of the terminal is lower than the voltage of the negative input terminal, the comparison circuit 101 outputs a low level.

The switch circuit 102 has two states of off and on, and can be implemented by a circuit composed of triodes or MOS transistors. In this embodiment, the switch circuit 102 can be selected as a low-level conduction switch circuit.

It can be understood that, in other embodiments, if the positive input terminal of the comparison circuit 101 is connected to the second power supply input terminal V2, and the negative input terminal of the comparison circuit 102 is connected to the first power supply input terminal V1, the switch circuit 102 can Select a switch circuit that is turned on at a high level.

The specific working principle is as follows: when the KL30 of the electric vehicle is in a non-power-down state, the voltage input by the second power input terminal V2 is greater than the voltage input by the first power input terminal V1, so the voltage of the positive input terminal of the comparison circuit 101 is smaller than the voltage input by the first power input terminal V1. For the voltage of the negative input terminal, the comparison circuit 101 outputs a low-level electrical signal to the controlled terminal of the switch circuit 102, and the switch circuit 102 is turned on. When the switch circuit 102 is in an on state, the first power input terminal V1 supplies power to the execution circuit 20 through the turned-on switch circuit 102. In this case, if an execution signal is input to the execution circuit 20 from the outside, the execution circuit 20 executes ASC. Operation, if no external execution signal is input to the execution circuit 20, the execution circuit 20 does not execute the ASC operation.

When the KL30 of the electric vehicle is powered off, the voltage input from the second power input terminal V2 gradually decreases. When the voltage input from the second power input terminal V2 is lower than the voltage input from the first power input terminal V1, the positive input of the comparison circuit 101 The voltage of the terminal is greater than the voltage of the negative input terminal. The comparison circuit 101 outputs a high-level electrical signal to the controlled terminal of the switch circuit 102 , and the switch circuit 102 is switched from an on state to an off state. When the switch circuit 102 is turned off, the electrical connection between the first power input terminal V1 and the execution circuit 20 is disconnected, and the execution circuit 20 is powered off. After the execution circuit 20 is powered off, the execution circuit 20 does not execute the ASC operation regardless of whether an execution signal is input to the execution circuit 20 from the outside. In this embodiment, the execution circuit 20 stops performing the ASC operation by cutting off the power supply of the execution circuit 20 when the KL30 is powered off, so that the IGBT can be prevented from being damaged due to the execution of the ASC operation when the driving voltage is insufficient.

In one embodiment, the switch circuit 102 may be composed of MOS transistors, and the MOS transistors in the switch circuit 102 are MOS transistors with a P-channel structure, which are controlled to be turned off by a high-level electrical signal, and their conduction is controlled by a low-level signal. Therefore, when the switch circuit 102 is cut off, the execution circuit 20 cannot perform the ASC operation; in practical applications, the MOS transistor in the switch circuit 102 can also be a MOS transistor with an N-channel structure. In this case, the comparison circuit The negative input of 101 is connected to the first power supply input terminal V1, and the positive input is connected to the second power supply input terminal V2. The comparison circuit 101 can control it to turn off by outputting a low-level electrical signal, and control it to turn on by a high-level signal. This will increase the cost. Specifically, since the low level output by the comparison circuit 101 is output relatively to the ground, and the source of the MOS transistor is not connected to the ground, it is necessary to perform non-common ground conversion, which may require adding other hardware. Therefore, if the positive input terminal of the comparison circuit 101 is connected to the first power input terminal V1, and the negative input terminal of the comparison circuit 101 is connected to the second power input terminal V2, the switch circuit 102 is selected as a low-level conduction switch circuit , which can reduce costs.

Optionally, the switch circuit 102 can also be composed of triodes, and the triodes in the switch circuit 102 can be PNP triodes, and the comparison circuit 101 can control the PNP triodes to turn off through a high-level electrical signal. The transistor in the switch circuit 102 can also be an NPN transistor. In this case, the negative input of the comparison circuit 101 is connected to the first power supply input terminal V1, and the positive input is connected to the second power supply input terminal V2. The comparison circuit 101 can output a low level by The electrical signal of 101 controls it to turn off, and the high level signal controls it to turn on, but this will increase the cost. Specifically, because the low level output by the comparison circuit 101 is output relatively, and the emitter of the triode is not connected to ground , and therefore need to do a common ground conversion, which may require additional hardware.

Optionally, referring to FIG. 2, in an embodiment, the switch circuit 102 includes a first resistor R1, a second resistor R2 and a first transistor Q1;

The first end of the first resistor R1 is connected to the first power input end V1, the second end of the first resistor R1 is connected to the first end of the second resistor R2, and the first end of the second resistor R2 is the The controlled end of the switch circuit 102, while the second end of the second resistor R2 is connected to the controlled end of the first transistor Q1; the input end of the first transistor Q1 is the power input end of the switch circuit 102, and the first transistor The output end of Q1 is the power output end of the switch circuit 102 .

The first transistor Q1 may be a P-MOS transistor or a PNP transistor.

The specific working principle is as follows: when the KL30 of the electric vehicle is in a non-power-down state, the comparison circuit 101 outputs a low-level electrical signal to the controlled end of the first transistor Q1, the first transistor Q1 is turned on, and the first power input end V1 supplies power to the execution circuit 20 through the turned-on first transistor Q1.

When the KL30 is powered off, the comparison circuit 101 outputs a high-level electrical signal to the controlled terminal of the first transistor Q1, the first transistor Q1 is turned off, the electrical connection between the first power input terminal V1 and the execution circuit 20 is disconnected, and the execution Circuit 20 is de-energized.

Optionally, referring to FIG. 3 , in an embodiment, the low-voltage power failure protection circuit further includes a signal detection circuit 30 and an execution signal input terminal IN;

The input end of the signal detection circuit 30 is connected to the execution signal input end IN, and the output end of the signal detection circuit 30 is connected to the signal input end of the execution circuit 20 .

The signal detection circuit 30 is used for detecting whether the execution signal input terminal IN has an execution signal input, and when an execution signal is input, transmits the execution signal to the execution circuit 20 to trigger the execution circuit 20 to execute the ASC operation. It should be noted that due to the power failure of the battery of the electric vehicle, there will be many times of power failure and reconnection, that is, the jitter situation, and the process of power failure and reconnection is often accompanied by a series of initial processes such as chip initialization. In a process, once the ASC signal is enabled, but the driving voltage has not been fully established, there will be a situation that the IGBT is not saturated and turned on and the ASC operation is performed. Therefore, in order to avoid the situation that the ASC operation is performed when the IGBT is not turned on in saturation, the delay time of the signal detection circuit 30 is set to be longer than the delay time required for the driving voltage to rise to satisfy the saturation conduction of the IGBT.

Optionally, referring to FIG. 4 , in an embodiment, the signal detection circuit 30 includes a third power input terminal V3, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, and a second capacitor C2 and the second transistor Q2;

The first terminal of the third resistor R3 is the input terminal of the signal detection circuit 30, the second terminal of the third resistor R3 is connected to the controlled terminal of the second transistor Q2, and the second terminal of the third resistor R3 is connected to the controlled terminal of the second transistor Q2. The first end of the fourth resistor R4 is connected, the second end of the third resistor R3 is connected to the first end of the first capacitor slave; the second end of the fourth resistor R4, the output end of the second transistor Q2 and the first end of the first capacitor are connected. The second terminals of a capacitor C1 are all grounded;

The first terminal of the fifth resistor R5 is connected to the third power input terminal V3, the second terminal of the fifth resistor R5 is the output terminal of the signal detection circuit 30, and the second terminal of the fifth resistor R5 is connected to the output terminal of the signal detection circuit 30. The input terminals of the two transistors Q2 are connected; and the second terminal of the fifth resistor R5 is connected to the first terminal of the second capacitor C2, and the second terminal of the second capacitor C2 is grounded.

In this embodiment, the third power input terminal V3 may be connected to the first low-voltage power supply Vin1, or other weak-current side power supplies that are not related to the triggering of the hardware ASC and have a relatively slow power-down speed (for example, the hardware ASC signal is triggered by the SBC, The low-voltage power supply VAUX is also generated by the SBC, so the power supply does not use the VAUX power supply generated by the SBC).

In this embodiment, the second transistor Q2 may be a triode or a MOS transistor. For the convenience of description, the second transistor Q2 is used as a high-level conducting transistor below, so that the execution circuit 20 will execute a high-level electrical signal when it receives a high-level electrical signal. The ASC operation is described as an example.

The specific working principle is as follows: when a high-level electrical signal is input to the execution signal input terminal IN, the second transistor Q2 is turned on. When the second transistor Q2 is turned on, the signal input terminal of the execution circuit 20 is at a low level, and the execution circuit 20 does not perform the ASC operation.

The second transistor Q2 is turned off when a low-level electrical signal is input to the execution signal input terminal IN. When the second transistor Q2 is turned off, the signal input terminal of the execution circuit 20 is pulled up to a high level by the fifth resistor R5. If the comparison switch circuit 10 is also in an on state at this time, the execution circuit 20 performs the ASC operation. .

Optionally, the following description will be given by taking the second transistor Q2 being a low-level conducting transistor, and taking the execution circuit 20 to perform an ASC operation when receiving a low-level electrical signal as an example.

The specific working principle is as follows: when a low-level electrical signal is input to the execution signal input terminal IN, the second transistor Q2 is turned on. When the second transistor Q2 is turned on, the signal input terminal of the execution circuit 20 is at a low level, and if the comparison switch circuit 10 is also turned on at this time, the execution circuit 20 performs the ASC operation.

When a high-level electrical signal is input to the execution signal input terminal IN, the second transistor Q2 is turned off. When the second transistor Q2 is turned off, the signal input terminal of the execution circuit 20 is pulled up to a high level by the fifth resistor R5, and the execution circuit 20 does not perform the ASC operation.

It should be noted that the execution circuit 20 needs to meet two conditions to perform the ASC operation. One is that the comparison switch circuit 10 is turned on, the first power input V1 supplies power to the execution circuit 20, and the second is that the execution circuit 20 receives the signal transmitted from the detection circuit 30. The incoming execution signal indicating the execution of the ASC operation.

Optionally, referring to FIG. 5 , in one embodiment, the execution circuit 20 includes a digital isolator 201 and an active short-circuit execution circuit 202;

The power terminal of the digital isolator 201 is the power terminal of the execution circuit 20 , the signal input terminal of the digital isolator 201 is the signal input terminal of the execution circuit 20 , and the signal output terminal of the digital isolator 201 is connected to the active short-circuit execution The input of circuit 202 is connected.

The digital isolator 201 is used to transmit the execution signal to the active short-circuit execution circuit 202, and it has strong anti-interference ability to ensure the stability and reliability of the system.

The active short circuit execution circuit 202 is used to execute the ASC operation.

The specific working principle is as follows: when the KL30 is in a non-power-down state, the comparison switch circuit 10 is turned on. When the comparison switch circuit 10 is turned on, the first power input terminal V1 supplies power to the digital isolator 201 through the turned-on comparison switch circuit 10. In this case, if the signal detection circuit 30 has an execution signal input to the digital isolator 201, the digital The isolator 201 transmits the execution signal to the active short-circuit execution circuit 202 to drive the active short-circuit execution circuit 202 to execute the ASC operation.

When the KL30 is powered off, the voltage input from the second power input terminal V2 gradually decreases. When the voltage input from the second power input terminal is lower than the voltage input from the first power input terminal V1, the comparison switch circuit 10 is turned off, and the digital isolator 201 is powered off. In this case, regardless of whether the signal detection circuit 30 detects the execution signal, the digital isolator 201 cannot transmit the execution signal to the active short-circuit execution circuit 202, and the active short-circuit execution circuit 202 does not perform the ASC operation.

Optionally, referring to FIG. 6 , in one embodiment, the low-voltage power failure protection circuit further includes a voltage-stabilizing circuit 40; the input end of the voltage-stabilizing circuit 40 is connected to the first low-voltage power source Vin1, and the voltage-stabilizing circuit 40 The output terminal is connected to the first power input terminal V1.

The voltage stabilizing circuit 40 is used for stabilizing the voltage output by the first low-voltage power source Vin1 to a certain voltage, providing a reference voltage for the comparison switch circuit 10 , and at the same time, supplying power to the execution circuit 20 .

Optionally, referring to FIG. 6, in one embodiment, the voltage regulator circuit 40 includes a sixth resistor R6, a voltage regulator diode T and a third capacitor C3; the first end of the sixth resistor R6 is connected to the first low-voltage power supply Vin1. connection, the sixth resistor R6 is connected to the first power input terminal V1, and the second end of the sixth resistor R6 is connected to the negative electrode of the zener diode T and the first end of the third capacitor C3; the zener diode T and the second terminal of the third capacitor C3 is grounded.

The Zener diode T is used to stabilize the voltage input from the first low-voltage power source Vin1 to a certain voltage.

Optionally, referring to FIG. 6 , in an embodiment, the low-voltage power failure protection circuit further includes an EMC filter circuit 50 , an anti-reverse connection circuit 60 and a filter circuit 70 ;

The input end of the EMC filter circuit 50 is connected to the second low-voltage power source Vin2, the output end of the EMC filter circuit 50 is connected to the input end of the anti-reverse connection circuit 60, and the output end of the anti-reverse connection circuit 60 is connected to the filter circuit 70 The input terminal of the filter circuit 70 is connected to the input terminal V2 of the second power supply.

The EMC filter circuit 50 is used for eliminating and suppressing electromagnetic interference in the electrical energy output by the second low-voltage power source Vin2.

The anti-reverse connection circuit 60 is used to prevent the back-end circuit from being damaged due to the reverse connection of the positive and negative poles of the second low-voltage power supply Vin2. Specifically, when the positive and negative poles of the second low-voltage power supply Vin2 are correctly connected, the output The electrical energy can be conducted to the back-end circuit, and the back-end circuit is powered off when the positive and negative electrodes of the second low-voltage power source Vin2 are incorrectly connected.

The filter circuit 70 is used for filtering the ripple in the electric energy output by the second low-voltage power source Vin2. Optionally, a seventh resistor R7 and a fourth capacitor C4 of the filter circuit 70, the first end of the seventh resistor R7 is connected to the output end of the anti-reverse connection circuit 60, and the first end of the seventh resistor R7 is connected to the first end of the seventh resistor R7. The first end of the four capacitors C4 is connected, and the second end of the fourth capacitor C4 is grounded; the second end of the seventh resistor R7 is the second power input end V2, that is, the second end of the seventh resistor R7 is compared with the The second comparison terminal of the switch circuit 10 is connected.

The present invention also provides a low-voltage power failure protection device. The low-voltage power failure protection device includes the above-mentioned low-voltage power failure protection circuit. The detailed structure of the low-voltage power failure protection circuit can refer to the above-mentioned embodiments. It will not be repeated; it can be understood that, because the above-mentioned low-voltage power failure protection circuit is used in the low-voltage power failure protection device of the present invention, the embodiment of the low-voltage power failure protection device of the present invention includes the above-mentioned low-voltage power failure protection circuit. All the technical solutions of all the embodiments of the protection circuit, and the technical effects achieved are also the same, and will not be repeated here.

The above descriptions are only optional embodiments of the present invention, and are not intended to limit the scope of the present invention. Under the inventive concept of the present invention, any equivalent structural transformations made by using the contents of the description and drawings of the present invention, or direct/indirect Applications in other related technical fields are included in the scope of patent protection of the present invention.

Claims (11)

1. A low-voltage power failure protection circuit, characterized in that the low-voltage power failure protection circuit comprises a first power input terminal communicated with a first low-voltage power supply, a second power input terminal communicated with a second low-voltage power supply, Compare the switch circuit and the executive circuit; The first comparison terminal of the comparison switch circuit is connected to the first power supply input terminal, the second comparison terminal of the comparison switch circuit is connected to the second power supply input terminal, and the power supply input terminal of the comparison switch circuit is connected to the second power supply input terminal. the first low-voltage power supply is connected, and the power output terminal of the comparison switch circuit is connected to the power supply terminal of the execution circuit; The comparison switch circuit is configured to disconnect the input power supply of the execution circuit according to a predetermined manner when the second low-voltage power supply is powered off, so that the execution circuit stops performing the active short-circuit operation. 2 . The low-voltage power failure protection circuit according to claim 1 , wherein the power input terminal of the comparison switch circuit is connected to the first power input terminal. 3 . 3. The low-voltage power failure protection circuit according to claim 2, wherein the comparison switch circuit comprises a comparison circuit and a switch circuit; The positive input terminal of the comparison circuit is the first comparison terminal of the comparison switch circuit, the negative input terminal of the comparison circuit is the second comparison terminal of the comparison switch circuit, and the output terminal of the comparison circuit is the same as the comparison circuit. The controlled end of the switch circuit is connected; The power input terminal of the switch circuit is the power input terminal of the comparison switch circuit, and the power output terminal of the switch circuit is the power output terminal of the comparison switch circuit. 4. The low-voltage power failure protection circuit according to claim 3, wherein the switch circuit comprises a first resistor, a second resistor and a first transistor; The first end of the first resistor is connected to the first power input end, the second end of the first resistor is connected to the first end of the second resistor, and the first end of the second resistor is the controlled end of the switch circuit, the second end of the second resistor is connected to the controlled end of the first transistor; The input end of the first transistor is the power input end of the switch circuit, and the output end of the first transistor is the power output end of the switch circuit. 5. The low-voltage power failure protection circuit according to claim 1, wherein the low-voltage power failure protection circuit further comprises a signal detection circuit and an execution signal input terminal; The input end of the signal detection circuit is connected with the execution signal input end, and the output end of the signal detection circuit is connected with the signal input end of the execution circuit. 6. The low-voltage power failure protection circuit according to claim 5, wherein the signal detection circuit comprises a third power input terminal, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second a capacitor and a second transistor; The first end of the third resistor is the input end of the signal detection circuit, the second end of the third resistor is connected to the controlled end of the second transistor, and the second end of the third resistor is connected to the controlled end of the second transistor. The first end of the fourth resistor is connected, the second end of the third resistor is connected to the first end of the first capacitor; the second end of the fourth resistor, the output end of the second transistor and the second end of the first capacitor is grounded; The first end of the fifth resistor is connected to the input end of the third power supply, the second end of the fifth resistor is the output end of the signal detection circuit, and the second end of the fifth resistor is connected to the output end of the signal detection circuit. the input end of the second transistor is connected; The second end of the fifth resistor is connected to the first end of the second capacitor, and the second end of the second capacitor is grounded. 7. The low-voltage power failure protection circuit according to claim 5, wherein the execution circuit comprises a digital isolator and an active short-circuit execution circuit; The power supply end of the digital isolator is the power supply end of the execution circuit, the signal input end of the digital isolator is the signal input end of the execution circuit, and the signal output end of the digital isolator is short-circuited with the active circuit The input terminals of the execution circuit are connected. 8. The low-voltage power failure protection circuit according to any one of claims 1-7, wherein the low-voltage power failure protection circuit further comprises a voltage regulator circuit; The input end of the voltage stabilization circuit is connected to the first low-voltage power supply, and the output end of the voltage stabilization circuit is connected to the input end of the first power supply. 9. The low-voltage power failure protection circuit according to claim 8, wherein the voltage regulator circuit comprises a sixth resistor, a voltage regulator diode and a third capacitor; The first end of the sixth resistor is connected to the first low-voltage power supply, the second end of the sixth resistor is connected to the input end of the first power supply, and the second end of the sixth resistor is connected to the stabilizer. The negative electrode of the voltage regulator diode is connected to the first end of the third capacitor; the positive electrode of the voltage regulator diode and the second end of the third capacitor are grounded. 10. The low-voltage power failure protection circuit according to claim 8, wherein the low-voltage power failure protection circuit further comprises an EMC filter circuit, an anti-reverse connection circuit and a filter circuit; The input end of the EMC filter circuit is connected to the second low-voltage power supply, the output end of the EMC filter circuit is connected to the input end of the anti-reverse connection circuit, and the output end of the anti-reverse connection circuit is connected to the filter The input end of the circuit is connected, and the output end of the filter circuit is connected with the input end of the second power supply. 11. A low-voltage power failure protection device, characterized in that, the low-voltage power failure protection device comprises the low-voltage power failure protection circuit according to any one of claims 1-10.

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