Control method for PFC circuit of air conditioner, and outdoor unit control circuit and air conditioner

Abstract

Disclosed in the present application are a control method for a PFC circuit of an air conditioner, and an outdoor unit control circuit and an air conditioner. The PFC circuit comprises a first bridge arm and a second bridge arm, wherein the first bridge arm comprises a first gallium nitride switch tube and a second gallium nitride switch tube that are connected in series. The air conditioner comprises a load module powered by the PFC circuit, wherein the load module comprises a compressor. The method comprises: acquiring an operation state of a compressor (S210); and on the basis of the operation state, controlling a first gallium nitride switch tube and a second gallium nitride switch tube, so as to reduce the current flowing through a freewheeling diode of the first gallium nitride switch tube and a freewheeling diode of the second gallium nitride switch tube during a startup process of the compressor (S220).

Description

Control method of PFC circuit of air conditioner, outdoor unit control circuit and air conditioner

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311123496.7 filed on August 31, 2023, entitled “Control method of PFC circuit of air conditioner, outdoor unit control circuit and air conditioner”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of air-conditioning circuits, and in particular to a control method for a PFC circuit of an air conditioner, an outdoor unit control circuit, and an air conditioner. Background Art

[0004] With the development of semiconductors, more efficient GaN switches are gradually being used in PFC circuits. However, due to the large voltage drop of GaN switches and the poor current-carrying capacity of their internal diodes, when used as rectifier diodes during compressor startup, the current flowing through the internal diodes is high, which can easily burn out the GaN switches.

[0005] Summary of the Invention

[0006] The purpose of this application is to at least partially solve one of the technical problems existing in the prior art and to provide a control method for a PFC circuit of an air conditioner, an outdoor unit control circuit, and an air conditioner.

[0007] In a first aspect, embodiments of the present application provide a method for controlling a PFC circuit of an air conditioner, wherein the PFC circuit includes a first bridge arm and a second bridge arm, the first bridge arm including a first gallium nitride switch tube and a second gallium nitride switch tube connected in series, the air conditioner including a load module powered by the PFC circuit, the load module including a compressor, the method comprising:

[0008] obtaining the operating status of the compressor; and

[0009] The first gallium nitride switch tube and the second gallium nitride switch tube are controlled according to the operating state to reduce the current flowing through the freewheeling diode of the first gallium nitride switch tube and the freewheeling diode of the second gallium nitride switch tube during the startup of the compressor.

[0010] According to some embodiments of the present application, the control method for a PFC circuit of an air conditioner includes an operating state of the compressor including an open-loop control state during startup. Controlling the first and second gallium nitride switching transistors according to the operating state includes:

[0011] When the compressor is in the open-loop control state, during the positive half cycle of the AC power supply, the first gallium nitride switch tube is controlled to be turned on and the second gallium nitride switch tube is controlled to be turned off; during the negative half cycle of the AC power supply, the first gallium nitride switch tube is controlled to be turned off and the second gallium nitride switch tube is controlled to be turned on.

[0012] According to the control method of the PFC circuit of an air conditioner provided in some embodiments of the present application, the air conditioner also includes a power module for inverting the output voltage of the PFC circuit to supply the compressor, and the open-loop control state is to control the power module according to a given first drive control current.

[0013] According to the control method of the PFC circuit of the air conditioner provided in some embodiments of the present application, the operating state of the compressor also includes a positioning state and a closed-loop control state. The positioning state is to control the power module according to a given second drive control current, and the closed-loop control state is to control the power module according to a given third drive control current and the actual operating parameters of the compressor.

[0014] In a second aspect, an embodiment of the present application provides an outdoor unit control circuit for an air conditioner, including a PFC circuit, a load module, and an MCU module, wherein:

[0015] The PFC circuit includes a first bridge arm and a second bridge arm, wherein the first bridge arm includes a first gallium nitride switch tube and a second gallium nitride switch tube connected in series;

[0016] The load module includes a compressor powered by the PFC circuit;

[0017] The MCU module is connected to the load module and the PFC circuit, respectively, and is used to obtain the operating status of the compressor and control the first gallium nitride switch tube and the second gallium nitride switch tube according to the operating status to reduce the current flowing through the freewheeling diode of the first gallium nitride switch tube and the freewheeling diode of the second gallium nitride switch tube during the startup of the compressor.

[0018] According to the external unit control circuit provided in some embodiments of the present application, the PFC circuit also includes a first inductor and a first capacitor, the second bridge arm includes a third switch tube and a fourth switch tube connected in series, one end of the AC power supply is connected to the connection point of the first gallium nitride switch tube and the second gallium nitride switch tube through the first inductor, the other end of the AC power supply is connected to the connection point of the third switch tube and the fourth switch tube, the first gallium nitride switch tube and the third switch tube are connected to one end of the first capacitor, and the second gallium nitride switch tube and the fourth switch tube are connected to the other end of the first capacitor.

[0019] According to some embodiments of the present application, the external machine control circuit further includes an input voltage sampling module connected to the first inductor, and an output end of the input voltage sampling module is connected to the MCU module.

[0020] According to some embodiments of the present application, the external machine control circuit further includes an input current sampling module connected to the first inductor, and the output end of the input current sampling module is connected to the MCU module.

[0021] According to some embodiments of the present application, the external machine control circuit further includes an output voltage sampling module connected to the first capacitor, and an output end of the output voltage sampling module is connected to the MCU module.

[0022] In a third aspect, an embodiment of the present application provides an operation control device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the control method as described in the embodiment of the first aspect above.

[0023] In a fourth aspect, an embodiment of the present application provides an air conditioner, comprising the outdoor unit control circuit as described in the embodiment of the second aspect above or comprising the operation control device as described in the embodiment of the third aspect above.

[0024] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the control method described in the embodiment of the first aspect above.

[0025] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. The purposes and other advantages of the present application can be achieved and obtained through the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0027] The present application is further described below with reference to the accompanying drawings and embodiments;

[0028] FIG1 is a circuit schematic diagram of a PFC circuit of an air conditioner provided in one embodiment of the present application;

[0029] FIG2 is a flow chart of a method for controlling a PFC circuit of an air conditioner according to an embodiment of the present application;

[0030] FIG3 is a diagram showing the operating state of the compressor of the air conditioner provided in an embodiment of the present application;

[0031] FIG4 is a flow chart of a method for controlling a PFC circuit of an air conditioner according to another embodiment of the present application; and

[0032] FIG5 is a schematic structural diagram of an operation control device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] This section will describe the specific embodiments of the present application in detail. The preferred embodiments of the present application are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present application, but it cannot be understood as a limitation on the scope of protection of the present application.

[0034] In the description of the embodiments of this application, "several" means one or more, "more" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, and "above," "below," and "within" are understood to include the number itself. "At least one" means one or more, "at least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. If "first," "second," or the like is used in the description, it is only for the purpose of distinguishing technical features and is not to be understood as indicating or implying relative importance, or implicitly indicating the number of the indicated technical features, or implicitly indicating the order of the indicated technical features.

[0035] It should be noted that the terms "dispose," "install," and "connect" in the embodiments of this application should be interpreted broadly. Those skilled in the art can reasonably determine the specific meanings of these terms in the embodiments of this application based on the specific content of the technical solution. For example, the term "connect" can refer to mechanical connection, electrical connection, or communication; it can refer to direct connection or indirect connection through an intermediary.

[0036] It should be noted that the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0037] With the development of semiconductors, more efficient GaN switches are gradually being used in PFC circuits. However, due to the large voltage drop of GaN switches and the poor current-carrying capacity of their internal diodes, when used as rectifier diodes during compressor startup, the current flowing through the internal diodes is high, which can easily burn out the GaN switches.

[0038] Based on this, the embodiments of the present application provide a control method for a PFC circuit of an air conditioner, an outdoor unit control circuit, and an air conditioner. By obtaining the operating status of the compressor and controlling the first gallium nitride switch tube and the second gallium nitride switch tube according to the operating status of the compressor, the current flowing through the freewheeling diode of the gallium nitride switch tube during the startup of the compressor is reduced, thereby avoiding a large current flowing through the freewheeling diode of the gallium nitride switch tube for a long time, thereby reducing the risk of burning out the gallium nitride switch tube and solving the problem of gallium nitride switch tube burning out.

[0039] The embodiments of the present application are further described below with reference to the accompanying drawings.

[0040] Referring to Figure 1, FIG1 is a schematic circuit diagram of a PFC circuit for an air conditioner provided in an embodiment of the present application. The PFC circuit includes a first bridge arm and a second bridge arm. The first bridge arm includes a first gallium nitride switch Q1 and a second gallium nitride switch Q2 connected in series. The air conditioner includes a load module powered by the PFC circuit, which includes a compressor. It is understood that the PFC circuit also includes a first inductor L and a first capacitor C1. The second bridge arm includes a third switch Q3 and a fourth switch Q4 connected in series. One end of the AC power source AC is connected to the junction of the first gallium nitride switch Q1 and the second gallium nitride switch Q2 via the first inductor L. The other end of the AC power source AC is connected to the junction of the third switch Q3 and the fourth switch Q4. The first gallium nitride switch Q1 and the third switch Q2 are connected to one end of the first capacitor C1, and the second gallium nitride switch Q3 and the fourth switch Q4 are connected to the other end of the first capacitor C1. In addition, the load module also includes loads such as a fan and a switching power supply. In addition, the air conditioner also includes an MCU module, which outputs PWM control signals to the control pins of the first GaN switch tube Q1, the second GaN switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4, thereby controlling the conduction and shutdown of the first GaN switch tube Q1, the second GaN switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4, thereby realizing the control of the PFC circuit operation mode. It can also be seen that the air conditioner further includes an input voltage sampling module and an input current sampling module connected to the input side of the PFC circuit, and an output voltage sampling module connected to the output side of the PFC circuit. Specifically, the input end of the input voltage sampling module is connected to the connection point between the AC power supply AC and the first inductor L, and the output end of the input voltage sampling module can be connected to the input port of the MCU module to transmit the measured input voltage Vac to the MCU module; the input end of the input current sampling module can be connected to the connection point between the first inductor L and the first bridge arm, and the output end of the input current sampling module is connected to the input port of the MCU module to transmit the measured input current Ipfc to the MCU module; the input end of the output voltage sampling module is connected to the connection point between the first capacitor C1 and the load module, and the output end of the output voltage sampling module can be connected to the input port of the MCU module to transmit the measured output voltage Vbus to the MCU module; the input port of the MCU module can also be connected to the load module to obtain actual operating parameters of the load module, for example, it can be connected to the compressor to obtain the compressor speed.

[0041] When the air conditioner is running with a light load, directly engaging high-frequency PFC control mode will result in high switching frequencies and significant circuit losses. Therefore, current air conditioner control methods require the compressor to enter closed-loop control before engaging high-frequency PFC control. The more efficient fourth-generation semiconductor GaN power transistors have internal freewheeling diodes with poor overcurrent capability. When used as high-frequency switches in bridgeless (totem-pole) PFC, if the GaN power transistor acts as a rectifier diode during the compressor's open-loop startup, the high current flowing through it can burn out the GaN power transistor.

[0042] 2 , a first embodiment of the present application provides a method for controlling a PFC circuit of an air conditioner, which is applied to the PFC circuit of the air conditioner shown in FIG1 . The control method includes but is not limited to steps S210 to S220:

[0043] Step S210: obtaining the operating status of the compressor;

[0044] Step S220: controlling the first GaN switch tube and the second GaN switch tube according to the operating state to reduce the current flowing through the freewheeling diode of the first GaN switch tube and the freewheeling diode of the second GaN switch tube during the compressor startup process.

[0045] According to the control method of the PFC circuit of the air conditioner provided by the embodiment of the present application, by obtaining the operating status of the compressor and controlling the first gallium nitride switch tube and the second gallium nitride switch tube according to the operating status of the compressor, the current flowing through the freewheeling diode of the gallium nitride switch tube during the startup of the compressor is reduced, thereby preventing a large current from flowing through the freewheeling diode of the gallium nitride switch tube for a long time, thereby reducing the risk of burning out the gallium nitride switch tube and solving the problem of gallium nitride switch tube burning out.

[0046] It should be noted that the compressor's operating states are shown in Figure 3. The compressor generally operates in three states from stop to stable operation: positioning state, open-loop control state, and closed-loop control state. It should be understood that the air conditioner also includes a power module that inverts the output voltage of the PFC circuit to supply the compressor. Specifically, the power module's input is connected to the output of the PFC circuit to obtain DC power, which is then inverted to produce the AC drive voltage required by the compressor. It should also be noted that when the compressor starts, it first enters the positioning state. During this state, the MCU module performs PWM control based on a given drive control current and outputs corresponding PWM signals to the power module to control its various switches. After the compressor is positioned, it enters the open-loop control state. In this state, the MCU module also performs PWM control based on a given drive control current and outputs corresponding PWM signals to the power module to control its various switches, without feedback adjustment based on the compressor's actual operating parameters combined with given control data. After operating in the open-loop control state for a period of time, the MCU module begins to control the power module based on the actual compressor operating parameters it collects and the compressor's required power.

[0047] In the control method for the PFC circuit of an air conditioner provided in some embodiments of the present application, the operating state of the compressor includes an open-loop control state during startup. Controlling the first and second GaN switching transistors according to the operating state in step S220 includes:

[0048] When the compressor is in open-loop control, during the positive half cycle of the AC power supply, the first GaN switch tube is controlled to be turned on and the second GaN switch tube is controlled to be turned off. During the negative half cycle of the AC power supply, the first GaN switch tube is controlled to be turned off and the second GaN switch tube is controlled to be turned on.

[0049] It is understandable that, due to the large current flowing through the PFC circuit in the open-loop control state during compressor startup, if the first and second GaN switches are used as rectifier diodes at this time, the current flowing through the freewheeling diodes inside the first and second GaN switches will also be very large. Therefore, in this embodiment, by controlling the first GaN switch to be turned on and the second GaN switch to be turned off during the positive half-cycle of the AC power supply, and controlling the first GaN switch to be turned off and the second GaN switch to be turned on during the negative half-cycle of the AC power supply, large current is avoided from flowing through the freewheeling diodes of the GaN switches for a long time, thereby reducing the risk of burning out the GaN switches.

[0050] Referring to Figure 4, which is a flow chart of a method for controlling a PFC circuit in an air conditioner according to one embodiment of the present application, when the compressor is stopped and needs to be started, it first enters a positioning state. The MCU module then determines whether the compressor has entered a switching control state based on the drive control current applied to the compressor's power module. If the compressor has entered an open-loop control state, the AC power supply voltage is determined. If the AC power supply voltage is greater than 0, it is in a positive half-cycle, at which point the first GaN switch Q1 is turned on and the second GaN switch Q2 is turned off. If the AC power supply voltage is less than 0, it is in a negative half-cycle, at which point the first GaN switch Q1 is turned off and the second GaN switch Q2 is turned on. If the compressor has not entered an open-loop control state, it enters a PFC control mode, for example, by performing high-frequency switching control on the PFC circuit.

[0051] In the control method of the PFC circuit of the air conditioner provided in some embodiments of the present application, the air conditioner also includes a power module that inverts the output voltage of the PFC circuit to supply the compressor, and the open-loop control state is to control the power module according to a given first drive control current.

[0052] It should be noted that, in the open-loop control state, the given first driving control current is generally obtained by synthesizing the direct-axis current Id and the quadrature-axis current Iq.

[0053] In the control method of the PFC circuit of the air conditioner provided in some embodiments of the present application, the operating state of the compressor also includes a positioning state and a closed-loop control state. The positioning state is to control the power module according to a given second drive control current, and the closed-loop control state is to control the power module according to a given third drive control current and the actual operating parameters of the compressor.

[0054] It should be noted that, in the positioning state, the given second drive control current generally only includes the DC current Id; in the closed-loop control state, the given third drive control current is generally synthesized by the direct-axis current Id and the quadrature-axis current Iq, and the third drive control current is generally converted from the required power of the compressor.

[0055] 1 , a second embodiment of the present application provides an outdoor unit control circuit for an air conditioner, including a PFC circuit, a load module, and an MCU module, wherein:

[0056] The PFC circuit includes a first bridge arm and a second bridge arm, wherein the first bridge arm includes a first gallium nitride switch tube Q1 and a second gallium nitride switch tube Q2 connected in series;

[0057] The load module includes a compressor powered by a PFC circuit;

[0058] The MCU module is connected to the load module and the PFC circuit, respectively, and is configured to obtain the operating status of the compressor and control the first and second GaN switching transistors based on the operating status to reduce the current flowing through the freewheeling diodes of the first and second GaN switching transistors during compressor startup. Specifically, the MCU module can be used to execute the PFC circuit control method described in the first embodiment.

[0059] According to the outdoor unit control circuit of the air conditioner provided by the embodiment of the present application, by obtaining the operating status of the compressor and controlling the first gallium nitride switch tube and the second gallium nitride switch tube according to the operating status of the compressor, the current flowing through the freewheeling diode of the gallium nitride switch tube during the startup of the compressor is reduced. This prevents a large current from flowing through the freewheeling diode of the gallium nitride switch tube for a long time, thereby reducing the risk of burning out the gallium nitride switch tube and solving the problem of gallium nitride switch tube burning out.

[0060] 1 , in the external unit control circuit provided in some embodiments of the present application, the PFC circuit further includes a first inductor L and a first capacitor C1, the second bridge arm includes a third switch tube Q3 and a fourth switch tube Q4 connected in series, one end of the AC power supply AC is connected to the connection point of the first gallium nitride switch tube Q1 and the second gallium nitride switch tube Q2 through the first inductor L, the other end of the AC power supply AC is connected to the connection point of the third switch tube Q3 and the fourth switch tube Q4, the first gallium nitride switch tube Q1 and the third switch tube Q3 are connected to one end of the first capacitor C1, and the second gallium nitride switch tube Q2 and the fourth switch tube Q4 are connected to the other end of the first capacitor C1.

[0061] 1 , in some embodiments of the present application, the external machine control circuit further includes an input voltage sampling module connected to the first inductor L, and an output end of the input voltage sampling module is connected to the MCU module.

[0062] In this embodiment, the input voltage sampling module transmits the collected input voltage Vac to the MCU module so that the MCU module controls the PFC circuit.

[0063] 1 , in some embodiments of the present application, the external machine control circuit further includes an input current sampling module connected to the first inductor L, and an output end of the input current sampling module is connected to the MCU module.

[0064] In this embodiment, the input voltage sampling module transmits the collected input current Ipfc to the MCU module so that the MCU module controls the PFC circuit.

[0065] In the external machine control circuit provided in some embodiments of the present application, an output voltage sampling module connected to the first capacitor C1 is further included, and an output end of the output voltage sampling module is connected to the MCU module.

[0066] In this embodiment, the output voltage sampling module transmits the collected output voltage Vbus to the MCU module, so that the MCU module controls the PFC circuit.

[0067] In addition, referring to Figure 5, the third aspect embodiment of the present application provides an operation control device 500, including a memory 510, a processor 520, and a computer program stored on the memory 510 and executable on the processor 520. The processor 520 executes the program to implement the control method of the first aspect embodiment above, for example, executing method steps S210 to S220 in Figure 2.

[0068] According to the operation control device provided in the embodiment of the present application, by obtaining the operating status of the compressor and controlling the first gallium nitride switch tube and the second gallium nitride switch tube according to the operating status of the compressor, the current flowing through the freewheeling diode of the gallium nitride switch tube during the startup of the compressor is reduced, thereby avoiding a large current flowing through the freewheeling diode of the gallium nitride switch tube for a long time, thereby reducing the risk of burning of the gallium nitride switch tube and solving the problem of gallium nitride switch tube burning.

[0069] In a fourth aspect, an embodiment of the present application provides an air conditioner, comprising the outdoor unit control circuit of the embodiment of the second aspect above or the operation control device 500 of the embodiment of the third aspect above.

[0070] According to the air conditioner provided in the embodiment of the present application, the operating status of the compressor is obtained and the first gallium nitride switch tube and the second gallium nitride switch tube are controlled according to the operating status of the compressor, thereby reducing the current flowing through the freewheeling diode of the gallium nitride switch tube during the startup of the compressor. This prevents a large current from flowing through the freewheeling diode of the gallium nitride switch tube for a long time, thereby reducing the risk of burning out the gallium nitride switch tube and solving the problem of gallium nitride switch tube burning out.

[0071] In the fifth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores computer-executable instructions. The computer-executable instructions are used to enable a computer to execute the control method of the embodiment of the first aspect above, for example, executing method steps S210 to S220 in Figure 2.

[0072] According to the computer-readable storage medium provided in the embodiments of the present application, by obtaining the operating status of the compressor and controlling the first gallium nitride switch tube and the second gallium nitride switch tube according to the operating status of the compressor, the current flowing through the freewheeling diode of the gallium nitride switch tube during the startup of the compressor is reduced, thereby preventing a large current from flowing through the freewheeling diode of the gallium nitride switch tube for a long time, thereby reducing the risk of burning out the gallium nitride switch tube and solving the problem of gallium nitride switch tube burning out.

[0073] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on computer-readable media, which can include computer storage media or non-transitory media and communication media or transient media. As is well known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVDs) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, as is well known to those skilled in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0074] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the purpose of the present application.

Claims

1. A method for controlling a PFC circuit of an air conditioner, wherein: The PFC circuit includes a first bridge arm and a second bridge arm, the first bridge arm includes a first gallium nitride switch tube and a second gallium nitride switch tube connected in series, the air conditioner includes a load module powered by the PFC circuit, the load module includes a compressor, and the method includes: Acquiring the operating status of the compressor; and The first gallium nitride switch tube and the second gallium nitride switch tube are controlled according to the operating state to reduce the current flowing through the freewheeling diode of the first gallium nitride switch tube and the freewheeling diode of the second gallium nitride switch tube during the startup of the compressor.

2. The control method according to claim 1, wherein: The operating state of the compressor includes an open-loop control state during startup, and the controlling the first gallium nitride switch tube and the second gallium nitride switch tube according to the operating state includes: When the compressor is in the open-loop control state, in the positive half cycle of the AC power supply, the first gallium nitride switch tube is controlled to be turned on and the second gallium nitride switch tube is controlled to be turned off. In the negative half cycle of the AC power supply, the first gallium nitride switch tube is controlled to be turned off and the second gallium nitride switch tube is controlled to be turned on.

3. The control method according to claim 2, wherein: The air conditioner further includes a power module for inverting the output voltage of the PFC circuit to supply the power to the compressor, and the open-loop control state is to control the power module according to a given first drive control current.

4. The control method according to claim 3, wherein: The operating state of the compressor also includes a positioning state and a closed-loop control state. The positioning state is to control the power module according to a given second drive control current, and the closed-loop control state is to control the power module according to a given third drive control current and actual operating parameters of the compressor.

5. An external unit control circuit of an air conditioner, comprising: The PFC circuit comprises a first bridge arm and a second bridge arm, wherein the first bridge arm comprises a first gallium nitride switch tube and a second gallium nitride switch tube connected in series; a load module, comprising a compressor powered by the PFC circuit; as well as The MCU module is connected to the load module and the PFC circuit respectively, and is used to obtain the operating status of the compressor and control the first gallium nitride switch tube and the second gallium nitride switch tube according to the operating status to reduce the current flowing through the freewheeling diode of the first gallium nitride switch tube and the freewheeling diode of the second gallium nitride switch tube during the startup of the compressor.

6. The external machine control circuit according to claim 5, wherein: The PFC circuit also includes a first inductor and a first capacitor, the second bridge arm includes a third switch tube and a fourth switch tube connected in series, one end of the AC power supply is connected to the connection point of the first gallium nitride switch tube and the second gallium nitride switch tube through the first inductor, the other end of the AC power supply is connected to the connection point of the third switch tube and the fourth switch tube, the first gallium nitride switch tube and the third switch tube are connected to one end of the first capacitor, and the second gallium nitride switch tube and the fourth switch tube are connected to the other end of the first capacitor. 7 . The external machine control circuit according to claim 6 , further comprising an input voltage sampling module connected to the first inductor, wherein an output end of the input voltage sampling module is connected to the MCU module.

8. The external machine control circuit according to claim 6 or 7, further comprising an input current sampling module connected to the first inductor, wherein an output end of the input current sampling module is connected to the MCU module. 9 . The external machine control circuit according to claim 6 , further comprising an output voltage sampling module connected to the first capacitor, wherein an output end of the output voltage sampling module is connected to the MCU module.

10. An operation control device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the control method according to any one of claims 1 to 4.

11. An air conditioner, comprising the external unit control circuit according to any one of claims 5 to 9 or the operation control device according to claim 10.

12. A computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to enable a computer to execute the control method according to any one of claims 1 to 4.

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