CN-224218109-U - Overcurrent protection circuit and air conditioner

CN224218109UCN 224218109 UCN224218109 UCN 224218109UCN-224218109-U

Abstract

The utility model discloses an overcurrent protection circuit and an air conditioner, wherein the overcurrent protection circuit is used for a driving circuit of a variable frequency motor, the driving circuit comprises a driving controller, the driving circuit is used for receiving a control signal and outputting a PWM signal, the overcurrent protection circuit comprises an overcurrent detection circuit which is used for detecting that the current output by an inverter circuit exceeds an overcurrent protection set value, outputting an overcurrent protection signal, sending the overcurrent protection signal to the driving controller, the driving controller controls the driving circuit to cut off the output PWM signal, a self-locking circuit which is used for receiving the overcurrent protection signal and a self-locking reset signal output by the driving controller, and when the self-locking reset signal is of a first level, the self-locking circuit is used for receiving the overcurrent protection signal and outputting the self-locking signal and is used for enabling the driving circuit to cut off the output PWM signal, and when the self-locking reset signal is of a second level different from the first level, the self-locking reset signal is reset. The utility model can realize the two-stage overcurrent protection of the driving circuit.

Inventors

SHEN QIANJUN
ZHENG SHIYI
LI XIZHI
JIANG XUEXIANG

Assignees

青岛海信日立空调系统有限公司

Dates

Publication Date: 20260508
Application Date: 20250429

Claims (9)

1. An overcurrent protection circuit for a drive loop of a variable frequency motor, the drive loop comprising: The driving controller is used for outputting a control signal for driving the variable frequency motor to work; A driving circuit for receiving the control signal and outputting a PWM signal for controlling a switching tube in an inverter circuit, wherein the overcurrent protection circuit includes: the overcurrent detection circuit is used for outputting an overcurrent protection signal when detecting that the current output by the inverter circuit exceeds an overcurrent protection set value, the overcurrent protection signal is sent to the drive controller, and the drive controller controls the drive circuit to cut off the output PWM signal; The self-locking circuit receives the overcurrent protection signal and a self-locking reset signal output by the driving controller, and when the self-locking reset signal is at a first level, the self-locking circuit receives the overcurrent protection signal and outputs the self-locking signal for enabling the driving circuit to cut off the output PWM signal, and when the self-locking reset signal is at a second level different from the first level, the self-locking circuit resets.
2. The overcurrent protection circuit according to claim 1, wherein the overcurrent detection circuit includes: The comparator is provided with a first input end, a second input end and an output end, wherein the first input end receives a reference level, the second input end receives the current output by the inverter circuit through a resistor, and the output end outputs the overcurrent protection signal.
3. The overcurrent protection circuit of claim 2, wherein the overcurrent detection circuit further comprises: and the first filter circuit is arranged at the front end of the second input end and is used for filtering the voltage signal input to the second input end.
4. The overcurrent protection circuit of claim 2, wherein the overcurrent detection circuit further comprises: And the charging and discharging circuit is arranged at the output end of the comparator, and the output end of the charging and discharging circuit outputs the overcurrent protection signal.
5. The overcurrent protection circuit of claim 4, wherein the charge-discharge circuit comprises a first power supply, a first resistor, a second resistor, and a first capacitor; The first resistor and the first capacitor are connected in series between the first power supply and the ground, one end of the second resistor is connected with the output end of the comparator, the other end of the second resistor is connected with the common connection position of the first resistor and the first capacitor, and the common connection position of the first resistor and the first capacitor outputs the overcurrent protection signal.
6. The overcurrent protection circuit of claim 1, wherein the self-locking circuit comprises: The control end of the first switch control unit receives the self-locking reset signal, the first end of the first switch control unit is grounded, and the first switch control unit is a high-level conductive switch element; The control end of the second switch control unit receives the overcurrent protection signal, the first end of the second switch control unit is grounded, and the second end of the second switch control unit is connected with the second end of the first switch control unit, the self-locking signal and the common connection position of the pull-up resistor; and the control end of the third switch control unit is connected with the second end of the first switch control unit, the second end of the second switch control unit and the common connection position of the self-locking signal, the first end of the third switch control unit is grounded, and the second end of the third switch control unit is connected with the overcurrent protection signal.
7. The overcurrent protection circuit of claim 6, wherein the self-locking circuit further comprises: The second filter circuit is arranged at the control end of the second switch control unit and is used for filtering the voltage signal input to the control end of the second switch control unit; And the third filter circuit is arranged at the control end of the third switch control unit and is used for filtering the voltage signal input to the control end of the third switch control unit.
8. The overcurrent protection circuit of claim 6, wherein, The first switch control unit, the second switch control unit and the third switch control unit are NPN triodes respectively, the base electrode of each NPN triode is a control end of the NPN triode, the emitter electrode of each NPN triode is a first end of the NPN triode, and the collector electrode of each NPN triode is a second end of the NPN triode.
9. An air conditioner, comprising: A refrigerant circulation loop for circulating the refrigerant in a loop formed by the compressor, the condenser, the expansion valve and the evaporator; A drive circuit for driving a variable frequency motor that is a motor for a compressor, a motor for an outdoor fan, a motor for an indoor fan, and/or a motor for a drain pump in a drain pan, the drive circuit comprising: The driving controller is used for outputting a control signal for driving the variable frequency motor to work; The driving circuit is used for receiving the control signal and outputting a PWM signal and controlling a switching tube in the inverter circuit; the overcurrent detection circuit is used for outputting an overcurrent protection signal when detecting that the current output by the inverter circuit exceeds an overcurrent protection set value, the overcurrent protection signal is sent to the drive controller, and the drive controller controls the drive circuit to cut off the output PWM signal; The self-locking circuit receives the overcurrent protection signal and a self-locking reset signal output by the driving controller, and when the self-locking reset signal is at a first level, the self-locking circuit receives the overcurrent protection signal and outputs the self-locking signal for enabling the driving circuit to cut off the output PWM signal, and when the self-locking reset signal is at a second level different from the first level, the self-locking circuit resets.

Description

Overcurrent protection circuit and air conditioner Technical Field The utility model relates to the technical field of variable frequency motor protection, in particular to an overcurrent protection circuit and an air conditioner. Background In the driving technology in the field of variable frequency motors, a driving circuit needs to use a high-cost integrated chip (such as a latch or a comparator) to realize overcurrent protection design, or a discrete element is used to build the overcurrent protection circuit, but the latch of a protection signal cannot be realized, and driving control abnormality is caused to damage the driving circuit when the overcurrent signal changes at high frequency and driving software is out of control and other abnormal states. Disclosure of utility model Aiming at the problems pointed out in the background art, the application provides an overcurrent protection circuit, wherein in a variable frequency motor driving circuit, an overcurrent protection signal is divided into two paths, one path is sent to a driving controller to control cutting-off PWM signal output, and the other path is sent to a self-locking circuit to output a self-locking signal to the driving circuit, so that the PWM signal output is cut off, and the two-stage overcurrent protection of the driving circuit is realized. In order to achieve the aim of the utility model, the utility model is realized by adopting the following technical scheme: some embodiments of the application relate to an overcurrent protection circuit for a drive loop of the variable frequency motor, the drive loop comprising: The driving controller is used for outputting a control signal for driving the variable frequency motor to work; A driving circuit for receiving the control signal and outputting a PWM signal for controlling a switching tube in an inverter circuit, the overcurrent protection circuit comprising: the overcurrent detection circuit is used for outputting an overcurrent protection signal when detecting that the current output by the inverter circuit exceeds an overcurrent protection set value, the overcurrent protection signal is sent to the drive controller, and the drive controller controls the drive circuit to cut off the output PWM signal; The self-locking circuit receives the overcurrent protection signal and a self-locking reset signal output by the driving controller, and when the self-locking reset signal is at a first level, the self-locking circuit receives the overcurrent protection signal and outputs the self-locking signal for enabling the driving circuit to cut off the output PWM signal, and when the self-locking reset signal is at a second level different from the first level, the self-locking circuit resets. The technical scheme related to the embodiment has the following advantages or beneficial effects: The overcurrent detection circuit detects that the current in the inverter circuit exceeds an overcurrent protection set value and outputs an overcurrent protection signal, the overcurrent protection signal is sent to the drive controller to control the drive circuit to cut off the output PWM signal to form a first-stage overcurrent protection, and on the other hand, the overcurrent protection signal is sent to the self-locking circuit to output the self-locking signal to control the drive circuit to cut off the output PWM signal to form a second-stage overcurrent protection, and the drive circuit stops working when the two-stage overcurrent protection ensures that the variable frequency motor works safely and reliably. When the driving controller does not reset the self-locking circuit, the self-locking signal forms self-locking on the self-locking circuit, and the output PWM signal is continuously cut off all the time, so that the driving control abnormality and the damage to the driving circuit caused by abnormal states such as high-frequency change of the overcurrent signal, out-of-control of the driving software and the like are avoided. In some embodiments of the application, the over-current detection circuit comprises: The comparator is provided with a first input end, a second input end and an output end, wherein the first input end receives a reference level, the second input end receives the current output by the inverter circuit through a resistor, and the output end outputs the overcurrent protection signal. The technical scheme related to the embodiment has the following advantages or beneficial effects: The overcurrent detection circuit adopts a voltage comparator, can set an overcurrent protection set value through a voltage dividing resistor, can compare the overcurrent protection set value, and achieves the aim of overcurrent detection. In some embodiments of the application, the over-current detection circuit further comprises: and the first filter circuit is arranged at the front end of the second input end and is used for filtering the voltage signal input to the second input end. Th