WO2013123820A1

WO2013123820A1 - Compressor demagnetization protection circuit, demagnetization protection method and air conditioner

Info

Publication number: WO2013123820A1
Application number: PCT/CN2012/088023
Authority: WO
Inventors: 郑长春; 卓森庆; 游剑波; 黄滔
Original assignee: 珠海格力电器股份有限公司
Priority date: 2012-02-24
Filing date: 2012-12-31
Publication date: 2013-08-29
Also published as: CN102761103B; CN102761103A

Abstract

A compressor demagnetization protection circuit, a demagnetization protection method, and an air conditioner. The compressor demagnetization protection circuit comprises: a current sampling module (10), used to collect a phase current of a compressor; a demagnetization protection module (20), connected to the current sampling module, and used to determine whether the phase current collected by the current sampling module is greater than a set current value, and output a determination signal; and a control module (30), connected to the demagnetization protection module, and used to receive the determination signal, and output a control signal corresponding to the determination signal to the compressor, so as to control the compressor to operate or stop. The compressor demagnetization protection circuit is capable of increasing a response speed of compressor demagnetization protection and simplifying the structure of a demagnetization protection circuit.

Description

Compressor demagnetization protection circuit and demagnetization protection method and air conditioner This application claims to be submitted to the China Intellectual Property Office on February 24, 2012, the application number is 201210045068.2, the name is "compressor demagnetization protection circuit and demagnetization protection method and air conditioner" The priority of the Chinese Patent Application, the entire disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of circuits, and in particular to a compressor demagnetization protection circuit, a demagnetization protection method, and an air conditioner. BACKGROUND OF THE INVENTION Due to the increase in the price of rare earths, the cost of rare earth permanent magnet motors for inverter air conditioners has risen sharply. In order to minimize the cost, in inverter air conditioners, more and more motors using ferrite magnet materials, namely ferrites, are used. Permanent magnet motor, compared with rare earth permanent magnet motor, the demagnetization current of ferrite permanent magnet motor is relatively small. If the protection measures are not perfect, it may cause the compressor to demagnetize under high current condition, which will cause the compressor performance to degrade and demagnetize. In severe cases, the compressor may even be damaged. Some compressor demagnetization protection schemes have been proposed in the prior art. At present, most of the compressor demagnetization protection circuits used are based on the software interrupt processing method or the conventional intelligent power module IPM (Intelligent Power Module, IPM for short) overcurrent protection hardware circuit solution (as shown in Figure 1), but The inventor found that: the processing method based on software interruption is slow in response to demagnetization protection; the protection scheme of the conventional intelligent power module uses many electrical components, the circuit structure is complex, and the protection point of the compressor demagnetization protection is low. Aiming at the problem that the compressor demagnetization protection scheme in the prior art has a slow response speed and a complicated circuit structure, an effective solution has not been proposed yet. SUMMARY OF THE INVENTION A primary object of the present invention is to provide a compressor demagnetization protection circuit, a demagnetization protection method, and an air conditioner to solve the problem of slow response speed and complicated circuit structure of the compressor demagnetization protection scheme in the prior art. In order to achieve the above object, according to an aspect of the present invention, a compressor demagnetization protection circuit is provided, comprising: a current sampling module for collecting a phase current of a compressor; and a demagnetization protection module connected to the current sampling module for Determining whether the phase current collected by the current sampling module is greater than a set current value, and inputting the determination signal; And a control module, connected to the demagnetization protection module, for receiving the determination signal, and outputting a control signal corresponding to the determination signal to the compressor to control the compressor operation or stop. Further, the demagnetization protection module includes: a comparator; a first filtering submodule connected between the current sampling module and the input end of the comparator; and a second filtering submodule connected between the output end of the comparator and the control module . Further, the current sampling module includes: a first resistor, the first end is connected to the first current end of the three-phase winding, the second end is connected to the input end of the first filtering sub-module; and the second end is connected to the third end a second current end of the phase winding, the second end is connected to the input end of the first filter sub-module; and a third resistor, the first end is simultaneously connected to the third current end of the three-phase winding and the input end of the first filter sub-module The second end is grounded. Further, the first filtering submodule includes: a first capacitor; and a fourth resistor, the first end is connected to the current sampling module as an input end of the first filtering submodule, and the second end is connected to the positive phase input end of the comparator, And the second end of the fourth resistor is further connected to the ground via the first capacitor. Further, the demagnetization protection module further includes: a fifth resistor and a second capacitor, wherein the first end of the fifth resistor and the first end of the second capacitor are both connected to the inverting input end of the comparator, and the second end of the fifth resistor And a second end of the second capacitor is grounded; a sixth resistor, the first end is connected to the inverting input end of the comparator, the second end is connected to the first power source; and the first diode and the second diode are Wherein the anode end of the first diode is grounded, the cathode end of the first diode and the anode end of the second diode are both connected to the first node, and the cathode end of the second diode is connected to the second node. The first node is a node between the second end of the fourth resistor and the non-inverting input of the comparator, and the second node is a node between the second end of the sixth resistor and the first power source. Further, the control module is an intelligent power module. Further, the second filtering submodule includes: a seventh resistor, the first end is connected to the output end of the comparator, the second end is connected to the signal input end of the smart power module; and the third end is connected to the smart power The signal input terminal of the module is grounded at the second end. Further, the demagnetization protection module further includes: an eighth resistor, the first end is connected to the output end of the comparator, and the second end is connected to the second power source. Further, the compressor demagnetization protection circuit further includes: a temperature compensation module connected between the first power source and the opposite input end of the comparator for detecting the temperature of the compressor. Further, the temperature compensation module includes: a thermistor, the first end is connected to the first power source; and the ninth resistor, the first end is connected to the second end of the thermistor, and the second end is connected to the opposite end of the comparator To the input. In order to achieve the above object, according to another aspect of the present invention, a compressor demagnetization protection method is provided, including: a current sampling module collecting a phase current of a compressor; and a demagnetization protection module determining whether a phase current collected by the current sampling module is greater than a set a predetermined current value, and outputting a judgment signal; and the control module receives the determination signal, and outputs a control signal corresponding to the determination signal to the compressor to control the compressor operation or the shutdown, wherein, if the current sampling module collects the phase current If it is greater than the set current value, the demagnetization protection module outputs a high level signal, the control module receives a high level signal, and outputs a control signal corresponding to the high level signal to the compressor to control the compressor to stop, if the current is sampled If the phase current collected by the module is less than or equal to the set current value, the demagnetization protection module outputs a low level signal, the control module receives the low level signal, and outputs a control signal corresponding to the low level signal to the compressor to Control compressor operation. Further, the set current value is determined by the following formula: j = ^cc R2 + R3

p—RS3 ' where ^ is the set current value, Vcc is the voltage of the first power supply in the demagnetization protection module, R2 is the resistance value of the sixth resistor in the demagnetization protection module, and R3 is the fifth in the demagnetization protection module The resistance of the resistor, RS3 is the resistance of the third resistor in the current sampling module. In order to achieve the above object, according to another aspect of the present invention, an air conditioner comprising any of the compressor demagnetization protection circuits provided by the above-described contents of the present invention is provided. Through the invention, a compressor demagnetization protection circuit comprising the following structure is adopted: a current sampling module for collecting phase current of the compressor; a demagnetization protection module connected to the current sampling module for determining a phase current collected by the current sampling module Whether it is greater than the set current value and input the judgment signal; and the control module is connected with the demagnetization protection module for receiving the judgment signal, and outputs the control signal to the compressor to control the compressor operation or stop, through the sampling module pair The phase current of the compressor is collected. When the phase current of the compressor is greater than the set current value, the demagnetization protection module connected to the sampling module timely outputs a corresponding judgment signal to the control module, so that the control module controls the compressor to stop. The invention solves the problems of slow response speed and complicated circuit structure of the compressor demagnetization protection scheme in the prior art, thereby achieving the effects of improving the response speed of the compressor demagnetization protection and simplifying the structure of the demagnetization protection circuit. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in FIG. In the drawing: 1 is a detailed circuit diagram of a compressor demagnetization protection circuit according to the prior art; FIG. 2 is a circuit block diagram of a compressor demagnetization protection circuit according to an embodiment of the present invention; FIG. 3 is a first preferred embodiment of the present invention. FIG. 4 is a specific circuit schematic diagram of a compressor demagnetization protection circuit according to a second preferred embodiment of the present invention; and FIG. 5 is a compressor demagnetization protection method according to an embodiment of the present invention. flow chart. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. The invention will be described in detail below with reference to the drawings in conjunction with the embodiments. 2 is a block diagram showing the circuit structure of a compressor demagnetization protection circuit according to an embodiment of the present invention. As shown in FIG. 2, the compressor demagnetization protection circuit of this embodiment includes a current sampling module 10, a demagnetization protection module 20, and a control module 30. The current sampling module 10 is configured to collect a phase current of the compressor. The demagnetization protection module 20 is connected to the current sampling module 10 and configured to determine whether the phase current collected by the current sampling module 10 is greater than a set current value, and output a determination signal. Specifically, if the phase current collected by the current sampling module 10 is greater than the set current value, the demagnetization protection module 20 outputs a high level signal; if the phase current collected by the current sampling module 10 is less than or equal to the set current value, Then, the demagnetization protection module 20 outputs a low level signal. The control module 30 is coupled to the demagnetization protection module 20 for receiving a determination signal and outputting a control signal to the compressor to control compressor operation or shutdown. Specifically, if the demagnetization protection module 20 outputs a high level signal, the control module 30 receives a high level signal and outputs a control signal corresponding to the high level signal to the compressor to control the compressor to stop; if the demagnetization protection module When the low level signal is output, the control module 30 receives the low level signal and outputs a control signal corresponding to the low level signal to the compressor to control the compressor operation. In the compressor demagnetization protection circuit, the phase current of the compressor is collected by the current sampling module 10, and it can be timely determined whether the phase current of the compressor is greater than the demagnetization protection current of the compressor (ie, the set current value). The accuracy of the demagnetization protection of the compressor is improved. When the phase current of the compressor is greater than the set current value, the demagnetization protection module 20 connected to the current sampling module 10 outputs a corresponding determination signal to the control module 30 in time to make the control module 30 control compressor stop, solve the slow response of the compressor demagnetization protection scheme in the prior art, the circuit The complicated structure has the effect of improving the response speed of the compressor demagnetization protection, simplifying the demagnetization protection circuit structure and improving the accuracy of the compressor demagnetization protection. 3 is a wiring diagram of a compressor demagnetization protection circuit according to a first preferred embodiment of the present invention. As shown in FIG. 3, the compressor demagnetization protection circuit of the first preferred embodiment of the present invention includes a current sampling module 10 and a demagnetization protection module 20. And control module 30. The control module 30 is an intelligent power module IPM. The current sampling module 10 is composed of three resistors through a certain connection relationship, wherein the first end of the first resistor RS1 is connected to the first current end Iu of the three-phase winding, and the second end is connected with the fourth resistor in the demagnetization protection module 20 The first end of the second resistor RS2 is connected to the second current end Iv of the three-phase winding, and the second end is connected to the fourth resistor R1 of the demagnetization protection module 20; the first end of the third resistor RS3 is simultaneously The third current terminal Iw connected to the three-phase winding and one end of the fourth resistor R1 in the demagnetization protection module 20 are grounded. With the sampling circuit of this structure, the third resistor RS3 is used as the total current shunt resistor of the control module 30, and the combined current of the three-phase winding currents Iu, Iv, Iw of the compressor at any time can be sampled at the third resistor RS3/ (t;), then the voltage value f/(t) = /(0x «3 across the third resistor RS3, the voltage signal is sent to the next stage circuit through the differential signal line. The fourth resistor in the demagnetization protection module 20 R1 is connected to the current sampling module 10 as an input end of the demagnetization protection module 20. In the demagnetization protection module 20, the fourth resistor R1 and the first capacitor C1 constitute a first filter sub-module (ie, a comparator pre-stage filter circuit). Avoiding the high frequency interference introduced on the signal line causes the comparator to be incorrectly flipped and misprotected. The voltage signal U (t) sampled by the third resistor RS3 is filtered by the circuit to filter the high frequency ridge and then sent to the voltage comparator. The non-inverting input terminal. The anode end of the first diode D1 in the demagnetization protection module 20 is grounded, the cathode end of the first diode D1 and the anode end of the second diode D2 are connected to the first node, the second two Cathode end connection of pole tube D2 a second node, wherein the first node is a node between the second end of the fourth resistor R1 and the positive phase input of the comparator, and the second node is between the second end of the sixth resistor R2 and the first power source Vcc The node can filter the impulse noise introduced on the signal line through the first diode D1 and the second diode D2 to protect the comparator. The demagnetization protection reference circuit is composed of a sixth resistor R2, a fifth resistor R3 and a second capacitor. C2, sixth resistor

R2 is connected to the first power source Vcc, and the comparator inverting input terminal is divided by the sixth resistor R2 and the fifth resistor R3 to input the inversion voltage f/l, and the power input end of the comparator is connected to the power source Vccl, where:

The second capacitor C2 is used to filter out the interference and stabilize the flip voltage. Setting: The current demagnetizing current of the motor is a fixed value I. The maximum peak current of the compressor phase current detected during compressor operation is Imax, and the demagnetization protection current is Ip. To avoid false protection of the demagnetization protection circuit, I _P >Imax is satisfied, and I _P <I is required to avoid demagnetization, that is, when Imax, I _P and I satisfy Imax<I _P <I, the demagnetization protection circuit can perform normal demagnetization protection. effect. Then, the relationship that the first power source Vcc, the sixth resistor R2, the fifth resistor R3, and the third resistor RS3 should satisfy can be derived by the following: Because the flip voltage U1 of the comparator satisfies:

And because I>I _P >Imax, the formula is multiplied by RS3, and Ij is obtained:

Imax * RS3 < I _p * RS3 < I * RS3 According to the circuit principle, the demagnetization protection current Ip can be set to:

Get 1, 3 into 2, get:

R3

Imax * RS3 < Vcc - < I * RS3

R2 + R3 Because Imax can be experimentally obtained, I is a known value, and Vcc is also a known value in the actual circuit. Therefore, when performing compressor demagnetization protection or designing a compressor demagnetization protection circuit, it can pass RS3, R2. The selection of R3 determines the magnitude of the set current (ie, the demagnetization protection current). The seventh resistor R6 and the third capacitor C3 form a second filter sub-module (SP, Cin filter circuit), and filter the high-level signal output by the comparator to avoid the high-frequency interference introduced on the signal line to make the Cin of the IPM module The pin is falsely detected high, causing false protection. An eighth resistor R5 connected to the second power source Vcc2 is connected to the node between the seventh resistor R6 and the comparator. When the peak value of the phase current passing through the third resistor RS3 exceeds the set current protection point, the voltage of the comparator non-inverting input terminal is higher than the reference voltage of the inverting input terminal, and the comparator outputs a high level signal, and the signal passes through the Cin filter circuit. High IPM module protection pin Cin, IPM module immediately turns off PWM pulse width modulation (Pulse- Width) Modulation, abbreviated as PWM) The drive signal suppresses the current to continue to rise, and at the same time, the Fo pin outputs a low level to the compressor driver chip, allowing it to stop the PWM drive signal output of the IPM module and perform a protection shutdown. Among them, the IPM module: the intelligent power module, connected to the motor drive components, comes with a variety of protection functions; Cin pin is a protection function pin on the IPM module, when it receives a high level, the IPM module automatically shuts down The drive signal is interrupted to stop the motor; the Fo pin is a function pin on the IPM module. When the module detects overcurrent and undervoltage, this pin automatically outputs a low level. The compressor demagnetization protection circuit of the first preferred embodiment of the present invention can select the parameters of each component according to the magnitude of the demagnetization current I of the ferrite compressor and the maximum operating current Imax of the compressor to adjust the magnitude of the protection current. For precise protection. The compressor demagnetization protection circuit of the first preferred embodiment of the present invention solves the problems of slow response speed and complicated circuit structure of the compressor demagnetization protection scheme in the prior art, thereby achieving the response speed of improving the demagnetization protection of the compressor and simplifying the circuit structure. Effect. 4 is a wiring diagram of a compressor demagnetization protection circuit according to a second preferred embodiment of the present invention. As shown in FIG. 4, compared with the compressor demagnetization protection circuit of the first preferred embodiment of the present invention, the difference between the two is that The compressor demagnetization protection circuit of the second preferred embodiment further includes: a temperature compensation module 40, which is composed of a thermistor Rntc and a ninth resistor R4, wherein the thermistor Rntc and the ninth resistor R4 are connected in series, and one end is connected to the first A power supply Vcc has one end connected to the inverting input of the comparator. The thermistor Rntc is a negative temperature coefficient thermistor, δΡ, the resistance of the type of resistor decreases with an increase in temperature, and the compressor demagnetization protection circuit of the second preferred embodiment of the present invention passes through the thermistor Rntc and the ninth Resistor R4 forms the temperature compensation network of the demagnetization protection circuit. At this time, the comparator reverse input input point voltage and the demagnetization protection current calculation formula know:

R3

m = Vcc x

R2 x (Rntc + R4)

+ R3

R2 + Rntc + R4 because,

and so,

When the ambient temperature of the compressor becomes high, the resistance of Rntc becomes small, and the voltage division on the fifth resistor R3, that is, the comparator reference point voltage U1, also becomes larger, so that the demagnetization protection point Ip is raised. The high-temperature demagnetization current of the ferrite compressor is greater than the low-temperature demagnetization current, and the resistors R2, R3, R4 and Rntc are selected according to the working maximum current peak Imax and the compressor "temperature-demagnetization current curve". The effect of adaptive adjustment of compressor demagnetization protection current Ip at different temperatures. In this way, the compressor demagnetization protection point can be automatically raised under high temperature conditions, the compressor operating range under high temperature and high load can be widened, and the performance of the whole machine can be improved. From the above description, it can be seen that the demagnetization protection circuit of the ferrite compressor of the embodiment of the invention achieves the following technical effects: the circuit is simple and reliable, the protection response speed is fast, and the protection point precision is high. By increasing the temperature compensation function, the advantage of automatically compensating the protection current point according to the ambient temperature of the compressor is achieved, which has a significant effect on preventing demagnetization of the ferrite compressor and ensuring stable operation of the compressor under high temperature and high load conditions. . In order to achieve the above object, according to another aspect of the present invention, a compressor demagnetization protection method is provided, which is performed by any of the compressor demagnetization protection circuits provided by the above-described contents of the embodiments of the present invention, specifically, as shown in the figure As shown in FIG. 5, the compressor demagnetization protection method includes steps S502 to S506: S502: The current sampling module collects the phase current of the compressor.

S504: The demagnetization protection module determines whether the phase current collected by the current sampling module is greater than a set current value, and outputs a determination signal. Specifically, if the phase current collected by the current sampling module is greater than the set current value, the demagnetization protection module outputs a high level signal; if the phase current collected by the current sampling module is less than or equal to the set current value, the demagnetization protection The module outputs a low level signal.

S506: The control module receives the determination signal, and outputs a control signal corresponding to the determination signal to the compressor to control the compressor to run or stop. Specifically, if the demagnetization protection module outputs a high level signal, the control module receives a high level signal, and outputs a control signal corresponding to the high level signal to the compressor to control the compressor to stop; if the demagnetization protection module outputs low The level signal, the control module receives the low level signal, and outputs a control signal corresponding to the low level signal to the compressor to control the compressor operation. Among them, the set current value is determined by the following formula: j = ^cc R2 + R3

P- RS3 '

^ is the set current value, Vcc is the voltage of the first power source in the demagnetization protection module, R2 is the resistance value of the sixth resistor in the demagnetization protection module, and R3 is the resistance value of the fifth resistor in the demagnetization protection module, RS3 The resistance of the third resistor in the current sampling module. By collecting the phase current of the compressor, when the phase current of the compressor is greater than the set current value, the corresponding judgment signal is output in time to control the compressor stop, and the response of the compressor demagnetization protection scheme in the prior art is solved. The problem of slow speed and complicated circuit structure achieves the effect of improving the response speed of the compressor demagnetization protection and simplifying the structure of the demagnetization protection circuit. In addition, the embodiment of the present invention further provides an air conditioner, which may be any air conditioner having the compressor demagnetization protection circuit provided by the embodiment of the present invention, or any compression provided by the embodiment of the present invention. Air conditioner for machine demagnetization protection method. The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

A compressor demagnetization protection circuit, comprising:

a current sampling module for collecting phase current of the compressor;

a demagnetization protection module, connected to the current sampling module, configured to determine whether a phase current collected by the current sampling module is greater than a set current value, and output a determination signal;

And a control module, coupled to the demagnetization protection module, configured to receive the determination signal, and output a control signal corresponding to the determination signal to the compressor to control the compressor to run or stop.

2. The compressor demagnetization protection circuit according to claim 1, wherein the demagnetization protection module comprises:

Comparators;

a first filtering sub-module coupled between the current sampling module and an input of the comparator;

The second filtering sub-module is connected between the output of the comparator and the control module.

3. The compressor demagnetization protection circuit according to claim 2, wherein the current sampling module comprises:

a first resistor, the first end is connected to the first current end of the three-phase winding, and the second end is connected to the input end of the first filter sub-module;

a second resistor, the first end is connected to the second current end of the three-phase winding, and the second end is connected to the input end of the first filter sub-module;

And a third resistor, the first end is simultaneously connected to the third current end of the three-phase winding and the input end of the first filter sub-module, and the second end is grounded.

4. The compressor demagnetization protection circuit according to claim 3, wherein the first filter submodule comprises:

First capacitor; a fourth resistor, the first end being connected to the current sampling module as an input end of the first filter sub-module, the second end being connected to the non-inverting input end of the comparator, and the second end of the fourth resistor The terminal is also connected to ground via the first capacitor.

5. The compressor demagnetization protection circuit according to claim 4, wherein the demagnetization protection module further comprises:

a fifth resistor and a second capacitor, the first end of the fifth resistor and the first end of the second capacitor are both connected to an inverting input end of the comparator, and the second end of the fifth resistor The second end of the second capacitor is grounded;

a sixth resistor, the first end is connected to the inverting input end of the comparator, and the second end is connected to the first power source;

a first diode and a second diode, wherein an anode end of the first diode is grounded, and a cathode end of the first diode and an anode end of the second diode are connected to a first node, a cathode end of the second diode is coupled to the second node, wherein the first node is a node between a second end of the fourth resistor and a positive phase input of the comparator, The second node is a node between the second end of the sixth resistor and the first power source.

6. The compressor demagnetization protection circuit according to claim 5, wherein the control module is a smart power module.

7. The compressor demagnetization protection circuit according to claim 6, wherein the second filter sub-module comprises:

a seventh resistor, the first end is connected to the output end of the comparator, and the second end is connected to the signal input end of the smart power module;

The third capacitor has a first end connected to the signal input end of the smart power module and a second end grounded.

8. The compressor demagnetization protection circuit according to claim 7, wherein the demagnetization protection module further comprises:

The eighth resistor has a first end connected to the output end of the comparator and a second end connected to the second power source.

9. The compressor demagnetization protection circuit according to claim 8, further comprising: a temperature compensation module connected between the first power source and the opposite input end of the comparator for detecting the The temperature of the compressor.

10. The compressor demagnetization protection circuit according to claim 9, wherein the temperature compensation module comprises:

a thermistor, the first end being connected to the first power source;

And a ninth resistor, the first end is connected to the second end of the thermistor, and the second end is connected to the opposite input end of the comparator.

An air conditioner comprising the compressor demagnetization protection circuit according to any one of claims 1 to 10.

12. A compressor demagnetization protection method, comprising:

The current sampling module collects the phase current of the compressor;

The demagnetization protection module determines whether the phase current collected by the current sampling module is greater than a set current value, and outputs a determination signal;

The control module receives the determination signal and outputs a control signal corresponding to the determination signal to the compressor to control the compressor to operate or to stop.

The method according to claim 12, wherein the demagnetization protection module determines whether the phase current collected by the current sampling module is greater than a set current value, and outputs the determination signal comprises: if the demagnetization protection module determines If the phase current collected by the current sampling module is greater than the set current value, the demagnetization protection module outputs a high level signal; and if the demagnetization protection module determines that the phase current collected by the current sampling module is less than or equal to The set current value, the demagnetization protection module outputs a low level signal,

Receiving, by the control module, the determination signal, and outputting a control signal corresponding to the determination signal to the compressor, to control the compressor to run or stop: if the demagnetization protection module outputs the high level signal And the control module receives the high level signal, and outputs a control signal corresponding to the high level signal to the compressor to control the compressor to stop; and if the demagnetization protection module outputs The low level signal, the control module receives the low level signal, and outputs a control signal corresponding to the low level signal to the compressor to control the compressor operation.

14. Method according to claim 12, characterized in that the set current value is determined by the following formula:

R2 + R3

RS3 Where ^ is the set current value, and Vcc is the voltage of the first power source in the demagnetization protection module,

R2 is the resistance of the sixth resistor in the demagnetization protection module, R3 is the resistance of the fifth resistor in the demagnetization protection module, and RS3 is the resistance of the third resistor in the current sampling module.