Control circuit of air conditioner, control method for air conditioner, and air conditioner

Abstract

Disclosed in the present application are a control circuit of an air conditioner, a control method for an air conditioner, and an air conditioner. The control circuit comprises: a first switching circuit, which is used for controlling at an indoor unit side the connection state between a second power supply busbar and a communication line; a second switching circuit, which is used for controlling the connection state between the second power supply busbar and a power supply line of an outdoor unit, and controlling the connection state between the communication line and the power supply line of the outdoor unit; a first controller, which is disposed on the indoor unit side, is connected to the first switching circuit, and is used for controlling the voltage value between a first power supply busbar and the communication line on the basis of the adjustment of a conduction duty cycle of the first switching circuit; and a second controller, which is disposed on an outdoor unit side and is used for controlling the working state of the second switching circuit.

Description

Air conditioner control circuit and control method thereof, and air conditioner

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202410249378.9 and application date of March 5, 2024, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this application as a reference. Technical Field

[0003] The present application relates to the field of air conditioning, and in particular to a control circuit and a control method of an air conditioner, and an air conditioner. Background Art

[0004] The air conditioner includes an indoor unit and an outdoor unit. The outdoor unit is usually powered by the indoor unit. Since high-power loads such as the compressor, condenser, and fan motor are all installed in the outdoor unit, the power supply current of the outdoor unit is relatively large.

[0005] In the prior art, because the outdoor unit lacks direct power, a main relay is typically installed on the indoor unit's electrical control board to control the outdoor unit's power supply. The outdoor unit's power supply current passes through the indoor unit's electrical control board. Due to the high current drawn by the outdoor unit, the indoor unit's main relay requires a large size and size, complicating the layout design of the indoor unit's electrical control board. Furthermore, a short circuit in the outdoor unit's power line can easily cause a fire on the indoor unit side, posing a serious threat to personal safety. Summary of the Invention

[0006] In view of this, an embodiment of the present application provides a control circuit of an air conditioner, a control method thereof, and an air conditioner, aiming to reduce the hardware cost of an indoor unit electric control board and ensure power supply security.

[0007] The technical solution of the embodiment of the present application is implemented as follows:

[0008] In a first aspect, an embodiment of the present application provides a control circuit for an air conditioner, the air conditioner including an indoor unit and an outdoor unit, wherein a first power supply bus, a second power supply bus, and a communication line are provided between the indoor unit and the outdoor unit, and the control circuit includes:

[0009] a first switching circuit, provided on the indoor unit side and located between the second power supply bus and the communication line, for controlling the connection state between the second power supply bus and the communication line on the indoor unit side;

[0010] a second switching circuit, provided on the outdoor unit side and located between the second power supply bus and the communication line, for controlling the connection state between the second power supply bus and the power supply line of the outdoor unit, and controlling the connection state between the communication line and the power supply line of the outdoor unit;

[0011] a first controller, disposed at the indoor unit side, connected to the first switching circuit, and configured to control a voltage value between the first power supply bus and the communication line based on adjustment of a conduction duty cycle of the first switching circuit;

[0012] The second controller is arranged at the outdoor unit side, connected to the second switching circuit, and configured to control the working state of the second switching circuit.

[0013] In some embodiments, the control circuit further comprises:

[0014] A first positive temperature coefficient resistor is used to perform current limiting processing on the communication line; the first positive temperature coefficient resistor is arranged in the first switching circuit or the second switching circuit.

[0015] In some embodiments, the first switching circuit includes:

[0016] a first switch element, configured to control a connection state between the second power supply bus and the communication line; the first switch element being connected to the second power supply bus and the communication line;

[0017] A switch tube is used to control the on-off state of the first switch element based on the conduction duty cycle.

[0018] In some embodiments, the second switching circuit includes:

[0019] a second switching element, configured to control a connection state between the second power supply bus and a power supply line of the outdoor unit;

[0020] The third switch element is used to control the connection state between the communication line and the power supply line of the outdoor unit.

[0021] In some embodiments, the second switching element is a normally open relay, and the third switching element is a normally closed relay.

[0022] In some embodiments, the control circuit further comprises:

[0023] A first positive temperature coefficient resistor is used to perform current limiting processing on the communication line; the first positive temperature coefficient resistor is arranged in the first switching circuit or the second switching circuit.

[0024] In some embodiments, the control circuit further comprises:

[0025] a first communication circuit, provided at the indoor unit side, for sending communication signals from the indoor unit to the outdoor unit and receiving communication signals from the outdoor unit;

[0026] a second communication circuit, provided at the outdoor unit side, for sending a communication signal from the outdoor unit to the indoor unit, and receiving a communication signal from the indoor unit;

[0027] The first port of the first communication circuit is connected to the second port of the second communication circuit via the communication line, and the second port of the first communication circuit is connected to the first port of the second communication circuit via the second power supply bus and the second switching circuit.

[0028] In a second aspect, an embodiment of the present application provides a method for controlling a control circuit of an air conditioner as described in the first aspect of the embodiment of the present application, characterized in that the method includes:

[0029] In response to a power-on instruction, the first controller controls the first switching circuit to be on for a first set time period based on a set on-duty cycle, so that the outdoor unit is powered on and the second controller is started;

[0030] The second controller switches the working state of the second switching circuit so that the second power supply bus and the power supply line of the outdoor unit are connected;

[0031] The second controller switches the working state of the second switching circuit in response to starting the second set time, so that the communication line is disconnected from the power supply line of the outdoor unit;

[0032] The first controller controls the first switching circuit to be in an off state.

[0033] In some embodiments, the first controller controls the first switching circuit to be on for a first set duration based on a set on-duty cycle, including:

[0034] The first controller controls the voltage value between the first power supply bus and the communication line based on a set conduction duty cycle;

[0035] The setting of the on-duty cycle includes:

[0036] The set on-duty cycle is the first duty cycle; or the set on-duty cycle gradually increases from the second duty cycle to the third duty cycle and then remains unchanged.

[0037] In some embodiments, if the control circuit further includes a first positive temperature coefficient resistor for current limiting the alternating current transmitted by the communication line, the first set time length is directly proportional to the rated resistance value of the first positive temperature coefficient resistor.

[0038] In some embodiments, the method further comprises:

[0039] The first controller starts a first communication circuit, the second controller starts a second communication circuit, and the first communication circuit and the second communication circuit establish a communication loop;

[0040] After the second controller determines that the communication loop is established, it controls the AC load of the outdoor unit to operate;

[0041] Wherein, the first communication circuit is arranged on the indoor unit side, and the second communication circuit is arranged on the outdoor unit side.

[0042] In a third aspect, an embodiment of the present application provides a control circuit for the air conditioner described in one aspect of an embodiment of the present application, wherein the first controller and the second controller are configured to execute the steps of the method described in the second aspect of the embodiment of the present application.

[0043] In a fourth aspect, an embodiment of the present application provides an air conditioner, which includes an indoor unit and an outdoor unit, a first power supply bus, a second power supply bus and a communication line are arranged between the indoor unit and the outdoor unit, and the air conditioner also includes the control circuit as described in the third aspect of the embodiment of the present application.

[0044] In some embodiments, the air conditioner further includes: the first power supply bus is a live wire, and the second power supply bus is a neutral wire; or, the first power supply bus is a neutral wire, and the second power supply bus is a live wire.

[0045] The control circuit of the air conditioner provided in an embodiment of the present application includes: a first switching circuit, arranged on the indoor unit side and located between the second power supply bus and the communication line, for controlling the connection state between the second power supply bus and the communication line on the indoor unit side; a second switching circuit, arranged on the outdoor unit side and located between the second power supply bus and the communication line, for controlling the connection state between the second power supply bus and the power supply line of the outdoor unit, and controlling the connection state between the communication line and the power supply line of the outdoor unit; a first controller, arranged on the indoor unit side, connected to the first switching circuit, for controlling the voltage value between the first power supply bus and the communication line based on the adjustment of the conduction duty cycle of the first switching circuit; a second controller, arranged on the outdoor unit side, connected to the second switching circuit, for controlling the working state of the second switching circuit. Based on the reuse of the second power supply bus and the communication line, the indoor unit controls the power supply of the outdoor unit during the air conditioner startup phase, and the outdoor unit controls its own power supply during the air conditioner operation phase, so that the large power supply current of the outdoor unit does not flow into the indoor unit electronic control board, effectively avoiding indoor unit fires caused by short circuits in the outdoor unit power line and improving the safety of the indoor unit; the main relay of the indoor unit is eliminated, the size of the indoor unit electronic control board is reduced, and the internal installation space of the indoor unit is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG1 is a schematic structural diagram of a control circuit of an air conditioner according to an embodiment of the present invention;

[0047] FIG2 is a schematic diagram of a voltage waveform during soft switch startup in an application example of the present application;

[0048] FIG3 is a schematic structural diagram of a first switching circuit according to an embodiment of the present application;

[0049] FIG4 is a schematic structural diagram of a first switching circuit in an application example of the present application;

[0050] FIG5 is a schematic structural diagram of a second switching circuit according to an embodiment of the present application;

[0051] FIG6 is a schematic diagram of the structure of a control circuit in an application example of the present application;

[0052] FIG7 is a schematic diagram of the structure of a control circuit in an application example of the present application;

[0053] FIG8 is a schematic diagram of the structure of a control circuit in an application example of the present application;

[0054] FIG9 is a flow chart of a control method of a control circuit according to an embodiment of the present application;

[0055] FIG10 is a circuit diagram of an air conditioner in an application example of the present application;

[0056] FIG11 is a flow chart of a method for controlling an air conditioner from power-on to shutdown in an application example of the present application. DETAILED DESCRIPTION

[0057] The present application will be described in further detail below with reference to the accompanying drawings and embodiments.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0059] An embodiment of the present application provides a control circuit for an air conditioner. As shown in FIG1 , the air conditioner includes an indoor unit 800 and an outdoor unit 900. A first power supply bus 500, a second power supply bus 600, and a communication line 700 are disposed between the indoor unit 800 and the outdoor unit 900. The outdoor unit 900 includes a power supply line 1000. The control circuit includes a first switching circuit 100, a second switching circuit 200, a first controller 300, and a second controller 400. The first switching circuit 100 is disposed on the indoor unit 800 side, between the second power supply bus 600 and the communication line 700, and is configured to control the connection between the second power supply bus 600 and the communication line 700 on the indoor unit 800 side. The second switching circuit 200 is disposed on the outdoor unit 900 side, between the second power supply bus 600 and the communication line 700, and is configured to control the connection between the second power supply bus 600 and the power supply line 1000 of the outdoor unit 900, as well as the connection between the communication line 700 and the power supply line 1000 of the outdoor unit 900. The first controller 300 is provided on the indoor unit 800 side, connected to the first switching circuit 100, and configured to control the voltage between the first power supply bus 500 and the communication line 700 based on the adjustment of the conduction duty cycle of the first switching circuit 100. The second controller 400 is provided on the outdoor unit 900 side, connected to the second switching circuit 200, and configured to control the operating state of the second switching circuit 200.

[0060] It should be noted that in related art, outdoor unit loads include DC loads and AC loads. Since the outdoor unit's power supply is AC, the power supply must be rectified to DC by a rectifier circuit on the outdoor unit's power supply circuit. The rectified DC power is then converted to the outdoor unit's control power supply via a switching power supply circuit on the outdoor unit's power supply circuit, which is used to supply power to the outdoor unit's DC load. The outdoor unit's power supply is then converted to the outdoor unit's operating power supply via an AC-AC frequency conversion module or an AC-DC-AC frequency conversion module, which is used to supply power to the outdoor unit's AC load. A controller installed in the outdoor unit controls the operation of the outdoor unit's AC load.

[0061] It can be understood that during the power-on process of the outdoor unit of the air conditioner, the power supply of the outdoor unit is converted into the control power supply of the outdoor unit through the power supply line of the outdoor unit and supplied to the controller of the outdoor unit. After the controller of the outdoor unit is started, it controls the outdoor unit to convert the power supply into the working power supply of the outdoor unit and control the operation of the AC load.

[0062] Here, when the air conditioner does not receive a power-on command from the user, the indoor unit is in a standby state, waiting to receive a power-on command; the outdoor unit is in a stopped state, waiting to supply power to the outdoor unit after receiving a power-on command.

[0063] It should be noted that the period from the time an air conditioner begins operating after receiving a power-on command from the user can be divided into two phases: the startup phase and the operation phase. During the startup phase, the outdoor unit only operates with DC loads, drawing a relatively low current. During the operation phase, the controller installed in the outdoor unit controls the operation of its AC loads. Because high-power loads such as the compressor, condenser, and fan motor are all located in the outdoor unit, the supply current to the outdoor unit is relatively high.

[0064] It should be noted that the outdoor unit is typically powered by the indoor unit. Two power busbars are installed between the outdoor and indoor units to transmit the AC power from the indoor unit to the outdoor unit. In related technologies, a main relay is typically installed on the indoor unit's electronic control panel to control the outdoor unit's power supply. Therefore, the outdoor unit's power supply current passes through the indoor unit's electronic control panel. However, due to the high current supplied by the outdoor unit, the main relay on the indoor unit side is large in size and size, which makes the layout design of the indoor unit's electronic control panel difficult. Furthermore, if the outdoor unit's power line shorts, it can easily cause a fire on the indoor unit side, seriously endangering personal safety.

[0065] It should be noted that in the related art, since the outdoor unit is in a shutdown state when the air conditioner does not receive a power-on command from the user, no matter whether the main relay is set in the indoor unit or the outdoor unit, the on and off state of the main relay needs to be controlled by the controller of the indoor unit. If the main relay is set in the outdoor unit, even if the safety hazards caused by the large power supply current on the indoor unit side can be effectively avoided, a control line for controlling the main relay needs to be set between the indoor unit and the outdoor unit, and the external interface design of the indoor unit and the outdoor unit is greatly changed. Therefore, it is impossible to solve the safety hazards on the indoor unit side by directly setting the main relay in the outdoor unit.

[0066] It can be understood that the embodiment of the present application is based on the reuse of the second power supply bus 600 and the communication line 700. During the startup phase of the air conditioner, the indoor unit 800 controls the power supply of the outdoor unit 900, and during the operation phase of the air conditioner, the outdoor unit 900 controls its own power supply, thereby preventing the large power supply current of the outdoor unit 900 from passing into the indoor unit 800 electronic control board, effectively avoiding a fire in the indoor unit 800 caused by a short circuit in the power line of the outdoor unit 900, and improving the safety of the indoor unit 800; the main relay of the indoor unit 800 is eliminated, the volume of the indoor unit 800 electronic control board is reduced, and the internal installation space of the indoor unit 800 is saved.

[0067] Here, during the air conditioner startup phase, the indoor unit 800 starts up based on a power-on command from the user. After the indoor unit 800 operates normally, the first controller 300 controls the first switching circuit 100, causing the indoor unit 800 to supply power to the outdoor unit 900. This activates the second controller 400 of the outdoor unit 900, and during this phase, the supply current to the outdoor unit 900 is relatively low. During the air conditioner operation phase, based on the switching of the operating state of the second switching circuit 200, the second controller 400 controls the AC load of the outdoor unit 900 to start operation. During this phase, the supply current to the outdoor unit 900 is relatively high. During this phase of operation when the supply current to the outdoor unit 900 is relatively high, since the indoor unit 800 does not control the power supply to the outdoor unit 900, the high supply current from the outdoor unit 900 does not flow into the indoor unit 800 electrical control board. This effectively prevents fires in the indoor unit 800 caused by short circuits in the outdoor unit 900 power line, thereby improving the safety of the indoor unit 800.

[0068] It can be understood that in the embodiment of the present application, three connecting lines, namely a first power supply bus 500, a second power supply bus 600 and a communication line 700, are set between the outdoor unit 900 and the indoor unit 800. The first power supply bus 500 and the communication line 700 are connected to the outdoor unit 900. Since the power supply of the outdoor unit 900 is controlled by the second controller 400 during the operation stage of the air conditioner, a switching element is set in the second switching circuit 200 to control the connection status between the second power supply bus 600 and the power supply line 1000 of the outdoor unit 900, and the switching element is controlled by the second controller 400. Before the second controller 400 is started, the high-current relay is in the disconnected state, and the indoor unit 800 cannot supply power to the outdoor unit 900 via the first power supply bus 500 and the second power supply bus 600. Because the communication line 700 is in a conductive state and the supply current to the outdoor unit 900 is low during the air conditioner startup phase, the embodiment of the present application adds a first switching circuit 100 for controlling the connection between the second power bus 600 and the communication line 700 on the indoor unit 800 side. When the switch element provided on the outdoor unit 900 side is in an open state, the first switching circuit 100 is closed to connect the second power bus 600 and the communication line 700. The indoor unit 800 draws power from the second power bus 600 and supplies power to the outdoor unit 900 via the first power bus 500 and the communication line 700, thereby powering up the second controller 400. In addition to transmitting communication signals, the communication line 700 in the embodiment of the present application is also used to supply power to the outdoor unit 900 during the air conditioner startup phase. Based on the reuse of the second power bus 600 and the communication line 700, the embodiment of the present application eliminates the main relay of the indoor unit 800, reduces the size of the indoor unit 800's electronic control board, and saves internal installation space of the indoor unit 800.

[0069] It should be noted that, during the startup phase of the air conditioner, the first switching circuit 100 controls the conduction between the second power supply bus 600 and the communication line 700. The first switching circuit 100, the communication line 700, and the second switching circuit 200 form a temporary power supply line. If the first switching circuit 100 is directly controlled to be in a closed state, even if only the DC load of the outdoor unit 900 is powered, due to the large potential difference between the two ends of the first switching circuit 100, the power supply startup current of the outdoor unit 900 is still large compared to the communication current transmitted by the communication line 700. Therefore, it is necessary to increase the current withstand rating of the components on the temporary power supply line. The embodiment of the present application adopts a soft switch startup technology, sets the first switching circuit 100 as a soft switch, and controls the voltage value between the first power supply bus 500 and the communication line 700 based on the adjustment of the conduction duty cycle of the first switching circuit 100 during the startup phase of the air conditioner, thereby reducing the power supply startup current of the outdoor unit 900 and thereby reducing the current withstand rating of the components on the temporary power supply line.

[0070] Here, soft switching, as opposed to hard switching, specifically refers to a device used in a circuit to connect and disconnect a load. For example, if a circuit uses soft switching for startup, the load connection process is not instantaneous, but rather the voltage or current gradually increases from low to high. Compared to hard switching, soft switching effectively eliminates the current spike when the load is connected, resulting in a smoother current profile. Soft switching is typically achieved by adjusting the soft switch's on-duty cycle.

[0071] Here, duty cycle refers to the proportion of the power-on time relative to the total time within a pulse cycle. Duty cycle control, also known as pulse width modulation, controls the duty cycle of a voltage signal applied to a component at a certain frequency. By controlling the ratio of the on and off states of the switching element, the average voltage value of the voltage signal applied to the component is controlled, ultimately controlling the current flowing through the component.

[0072] In one application example of the present application, a schematic diagram of a voltage waveform for soft switching startup is provided, as shown in FIG2 . Within half a voltage cycle T / 2, the first switching circuit 100 is in an off state at Δt and in an on state at the rest of the time. By adjusting the ratio between Δt and T / 2, the voltage between the first power bus 500 and the communication line 700 can be controlled.

[0073] It should be noted that the power supply circuit 1000 of the outdoor unit 900 of the present embodiment includes a rectifier circuit and a switching power supply circuit. The rectifier circuit is used to rectify the power supply of the outdoor unit 900 into DC power, which is then supplied to the switching power supply circuit. The switching power supply circuit is used to convert the output power of the rectifier power supply into the operating power supply of the air conditioner. The rectifier circuit is typically provided with a support capacitor for filtering and stabilizing the output power of the rectifier power supply before supplying power to the switching power supply circuit.

[0074] It will be appreciated that, during the startup phase of the air conditioner, the embodiment of the present application controls the power supply voltage supplied from the indoor unit 800 to the outdoor unit 900 based on the adjustment of the conduction duty cycle of the first switching circuit 100, pre-charges the support capacitor on the power supply circuit 1000 of the outdoor unit 900, and when the voltage across the support capacitor reaches a preset voltage value, the switching power supply circuit on the power supply circuit 1000 of the outdoor unit 900 operates, and the second controller 400 starts. The embodiment of the present application employs a technical solution of pre-charging the support capacitor on the power supply circuit 1000 of the outdoor unit 900 before connecting the DC load of the outdoor unit 900. This effectively reduces the potential difference across the first switching circuit 100 when the DC load of the outdoor unit 900 is connected, thereby reducing the startup current of the power supply to the outdoor unit 900 and lowering the current rating of the components on the temporary power supply line.

[0075] For example, as shown in FIG3 , the first switching circuit 100 includes a first switching element 101 and a switching transistor 102. The first switching element 101 is connected to the second power supply bus 600 and the communication line 700 and is configured to control the connection between the second power supply bus 600 and the communication line 700. The switching transistor 102 is configured to control the on / off state of the first switching element 101 based on the on-duty cycle.

[0076] The switch tube 102 in the embodiment of the present application can be an IGBT (Insulated Gate Bipolar Transistor), or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or a triode, which is not limited in the embodiment of the present application.

[0077] Illustratively, the first switching element 101 comprises a combination of an optocoupler and a thyristor (SCR). The SCR has a high breakdown voltage and is used to transmit the power supply current to the outdoor unit 900. The optocoupler acts as an isolating switch, controlling the on / off state of the SCR based on the on / off state of the switch tube 102. When the first switching element 101 is on, the second power supply bus 600 and the communication line 700 are connected. When the first switching element 101 is off, the second power supply bus 600 and the communication line 700 are disconnected.

[0078] Exemplarily, the switch 102 is a triode. The collector of the switch 102 is connected to the optocoupler of the first switching element 101. The emitter of the switch 102 is grounded via a pull-down resistor R8. When the switch 102 is on, the optocoupler of the first switching element 101 is turned on; when the switch 102 is off, the optocoupler of the first switching element 101 is turned off. The base of the switch 102 is connected to the first controller 300. The first controller 300 controls the on / off state of the switch 102 based on the adjustment of the on-duty cycle of the first switching circuit 100, thereby controlling the on / off state of the first switching element 101.

[0079] In an application example of the present application, another first switching circuit 100 is provided, as shown in FIG4 . The first switching element 101 is a normally open relay, the main contacts of the first switching element 101 are connected to the second power supply circuit and the communication line 700, the coil of the first switching element 101 is connected to the switch tube 102, and the first controller 300 controls the on-off state of the switch tube 102 based on the adjustment of the on-duty cycle of the first switching circuit 100, thereby controlling the on-off state between the main contacts of the first switching element 101.

[0080] For example, as shown in FIG5 , the second switching circuit 200 includes a second switching element 201 and a third switching element 202. The second switching element 201 is used to control the connection between the second power supply bus 600 and the power supply line 1000 of the outdoor unit 900; the third switching element 202 is used to control the connection between the communication line 700 and the power supply line 1000 of the outdoor unit 900.

[0081] Exemplarily, the second switching element 201 is a normally open relay, and the third switching element 202 is a normally closed relay.

[0082] It is understood that during the air conditioner startup phase, since the second controller 400 is not started, the second switch element 201 is in the open state, and the indoor unit 800 cannot supply power to the outdoor unit 900 via the second power supply bus 600. The third switch element 202 is in the closed state, and when the first switching circuit 100 is in the conductive state, the indoor unit 800 supplies power to the outdoor unit 900 via the communication line 700. During the air conditioner operation phase, after the second controller 400 is started, it switches the operating state of the second switching circuit 200, closing the second switch element 201 and opening the third switch element 202. The second power supply bus 600 is conductive to the power supply line 1000 of the outdoor unit 900, and the communication line 700 is disconnected from the power supply line 1000 of the outdoor unit 900. At this time, the indoor unit 800 supplies power to the outdoor unit 900 via the second power supply bus 600.

[0083] It can be understood that when the second switching element 201 is closed, regardless of whether the first switching circuit 100 is in the on or off state, the indoor unit 800 supplies power to the outdoor unit 900 via the first power supply bus 500 and the second power supply bus 600. Therefore, during the operation stage of the air conditioner, the power supply control of the outdoor unit 900 does not require the participation of the first controller 300, so the large power supply current of the outdoor unit 900 will not pass into the electrical control board of the indoor unit 800.

[0084] Exemplarily, as shown in FIG6 and FIG7 , the control circuit includes a first positive temperature coefficient resistor 1100 for current limiting the communication line 700 ; the first positive temperature coefficient resistor 1100 is provided in the first switching circuit 100 or the second switching circuit 200 .

[0085] Here, the positive temperature coefficient resistor is a typical temperature-sensitive semiconductor resistor. When the temperature exceeds the Curie temperature, the resistance value of the positive temperature coefficient resistor increases stepwise as the temperature rises. The higher the temperature, the greater the resistance value.

[0086] It should be noted that positive temperature coefficient resistors are usually connected in series in the circuit as current limiting protection devices. When the circuit is working normally, the temperature of the positive temperature coefficient resistor is close to the working environment temperature. At this time, the resistance value of the positive temperature coefficient resistor is small and will not hinder the passage of current; when the current in the circuit is too large, the temperature of the positive temperature coefficient resistor rises due to the increase in power. When the temperature exceeds the Curie temperature, the resistance value of the positive temperature coefficient resistor will increase stepwise, and the current in the circuit will quickly decrease to a safe current value. At this time, the power of the positive temperature coefficient resistor decreases, the temperature resistance value of the positive temperature coefficient resistor decreases stepwise, and the circuit returns to normal operation.

[0087] It is understandable that when a positive temperature coefficient resistor is connected in series in a circuit for current limiting protection, the operating current value during normal operation of the circuit should not exceed the tripping current value of the positive temperature coefficient resistor. If the operating current value during normal operation of the circuit exceeds the tripping current value of the positive temperature coefficient resistor, the resistance value of the positive temperature coefficient resistor will frequently change in steps, affecting the normal operation of the circuit.

[0088] It can be understood that the first positive temperature coefficient resistor 1100 in the embodiment of the present application is used to perform current limiting protection on the temporary power supply line constructed by the first switching circuit 100, the communication line 700 and the second switching circuit 200 during the startup phase of the air conditioner. Since the first positive temperature coefficient resistor 1100 is not used to perform current limiting protection on the communication circuit, the first positive temperature coefficient resistor 1100 can be set in the first switching circuit 100 or in the second switching circuit 200.

[0089] It is understandable that if hard switching technology is used to control the conduction between the second power supply bus 600 and the communication line 700, the power supply starting current of the outdoor unit 900 is relatively large. Since the power supply current of the outdoor unit 900 should not exceed the tripping current value of the first positive temperature coefficient resistor 1100, the specifications and volume of the first positive temperature coefficient resistor 1100 are relatively large, which is not conducive to the selection and arrangement of the first positive temperature coefficient resistor 1100.

[0090] It can be understood that the first switching circuit 100 in the embodiment of the present application is configured as a soft switch, which effectively reduces the power supply startup current of the outdoor unit 900 and is beneficial to the selection and arrangement of the first positive temperature coefficient resistor 1100 .

[0091] For example, as shown in FIG8 , the control circuit further includes: a first communication circuit 1200 and a second communication circuit 1300. The first communication circuit 1200 is provided on the indoor unit 800 side and is used to transmit communication signals from the indoor unit 800 to the outdoor unit 900 and receive communication signals from the outdoor unit 900. The second communication circuit 1300 is provided on the outdoor unit 900 side and is used to transmit communication signals from the outdoor unit 900 to the indoor unit 800 and receive communication signals from the indoor unit 800. The first port of the first communication circuit 1200 is connected to the second port of the second communication circuit 1300 via the communication line 700, and the second port of the first communication circuit 1200 is connected to the first port of the second communication circuit 1300 via the second power supply bus 600 and the second switching circuit 200.

[0092] Here, the first port of the first communication circuit 1200 and the first port of the second communication circuit 1300 are sending ports, the second port of the first communication circuit 1200 and the second port of the second communication circuit 1300 are receiving ports, and the first communication circuit 1200 and the second communication circuit 1300 establish a communication loop via the communication line 700, the second power supply bus 600 and the second switching circuit 200.

[0093] It should be noted that, during the startup phase of the air conditioner, since the communication line 700 serves as a temporary power supply line to supply power to the outdoor unit 900 and the second controller 400 is not started, no communication is performed between the first communication circuit 1200 and the second communication circuit 1300; during the operation phase of the air conditioner, the indoor unit 800 supplies power to the outdoor unit 900 via the first power supply bus 500 and the second power supply bus 600, and the first communication circuit 1200 and the second communication circuit 1300 establish a communication loop via the communication line 700, the second power supply bus 600 and the second switching circuit 200. After the indoor unit 800 and the outdoor unit 900 confirm that the working status is normal, the second controller 400 starts the AC load of the outdoor unit 900.

[0094] The present application also provides a control method based on the aforementioned control circuit, as shown in FIG9 , the method comprising:

[0095] Step 901: In response to a power-on instruction, the first controller controls the first switching circuit to be turned on for a first set time period based on a set on-duty cycle, so that the outdoor unit is powered on and the second controller is started.

[0096] Step 902: The second controller switches the working state of the second switching circuit so that the second power supply bus and the power supply line of the outdoor unit are connected.

[0097] In step 903 , the second controller switches the working state of the second switching circuit in response to starting the second set time, so that the communication line is disconnected from the power supply line of the outdoor unit.

[0098] Step 904: The first controller controls the first switching circuit to be in an off state.

[0099] It can be understood that, in the control method of the embodiment of the present application, when the air conditioner does not receive a power-on command from the user, the indoor unit 800 is in a standby state and the outdoor unit 900 is in a shutdown state; when the air conditioner receives a power-on command from the user, the first controller 300 controls the first switching circuit 100 so that the communication line 700 and the second power supply bus 600 are connected, and the indoor unit 800 supplies power to the outdoor unit 900 via the first power supply bus 500 and the communication line 700, so that the outdoor unit 900 is powered on and the second controller 400 is started; after the second controller 400 is started, it is used for power supply control of the outdoor unit 900. At this time, the indoor unit 800 supplies power to the outdoor unit 900 via the first power supply bus 500 and the second power supply bus 600. The control method of the embodiment of the present application is based on the reuse of the second power supply bus 600 and the communication line 700. During the startup phase of the air conditioner, the indoor unit 800 controls the power supply of the outdoor unit 900, and during the operation phase of the air conditioner, the outdoor unit 900 controls its own power supply, thereby preventing the large power supply current of the outdoor unit 900 from passing into the indoor unit 800 electronic control board, effectively avoiding a fire in the indoor unit 800 caused by a short circuit in the power line of the outdoor unit 900, and improving the safety of the indoor unit 800; the main relay of the indoor unit 800 is eliminated, the volume of the indoor unit 800 electronic control board is reduced, and the internal installation space of the indoor unit 800 is saved.

[0100] It is understood that after step 902, the indoor unit 800 supplies power to the outdoor unit 900 via the first power bus 500 and the second power bus 600. To ensure power supply reliability, the communication line 700, the second power bus 600, and the power supply line 1000 of the outdoor unit 900 remain connected. Steps 903 and 904 are executed after a second set time has elapsed. The second set time is related to the closing time of the second switching element 201 of the second switching circuit 200 and is typically less than 1 second.

[0101] Exemplarily, the first controller controls the first switching circuit to be on for a first set duration based on a set on-duty cycle, including: the first controller controls the voltage value between the first power supply bus and the communication line based on the set on-duty cycle; wherein, setting the on-duty cycle includes: setting the on-duty cycle to a first duty cycle; or setting the on-duty cycle to gradually increase from the second duty cycle to a third duty cycle and then remain unchanged.

[0102] Here, the embodiment of the present application adopts soft switching starting technology. The first controller 300 controls the voltage value between the first power supply bus 500 and the communication line 700, and pre-charges the supporting capacitor on the power supply line 1000 of the outdoor unit 900. When the voltage across the supporting capacitor reaches the preset voltage value, the switching power supply circuit on the power supply line 1000 of the outdoor unit 900 works, and the second controller 400 starts.

[0103] It can be understood that the first switching circuit 100 acts as a soft switch on the temporary power supply line, and adjusts the ratio of the on-off time based on the set on-duty cycle to achieve voltage control between the first power supply bus 500 and the communication line 700. Among them, the set on-duty cycle is pre-configured by the first controller 300 and can be a constant first duty cycle, that is, in the startup stage of the air conditioner, the indoor unit 800 supplies power to the outdoor unit 900 with a constant voltage, and the power supply voltage of the outdoor unit 900 is less than the output voltage of the external power supply. When the voltage across the support capacitor on the power supply circuit 1000 of the outdoor unit 900 reaches a preset voltage value, the second controller 400 starts; the set on-duty cycle can also be gradually increased from the second duty cycle to the third duty cycle and then remains unchanged. As the voltage across the support capacitor on the power supply circuit 1000 of the outdoor unit 900 gradually increases, the first controller 300 controls the on-duty cycle to gradually increase, and the power supply voltage of the outdoor unit 900 gradually increases. When the voltage across the support capacitor on the power supply circuit 1000 of the outdoor unit 900 reaches a preset voltage value, the second controller 400 starts.

[0104] It should be noted that whether the on-duty cycle is set to the first duty cycle or gradually increases from the second duty cycle to the third duty cycle and then remains unchanged, the problem of high startup current of the outdoor unit 900 during the air conditioner startup phase can be solved. Compared with the method of using a hard switch to control the connection between the communication line 700 and the second power bus 600, the embodiment of the present application configures the first switching circuit 100 as a soft switch, which can reduce the current rating of components on the temporary power supply line. For example, the control circuit of the embodiment of the present application includes a first positive temperature coefficient resistor 1100. The use of soft switching startup technology facilitates the selection and placement of the first positive temperature coefficient resistor 1100.

[0105] Exemplarily, the control method further includes:

[0106] Step 905: The first controller starts the first communication circuit, and the second controller starts the second communication circuit. The first communication circuit and the second communication circuit establish a communication loop.

[0107] Step 906: After the second controller determines that the communication loop is established, it controls the AC load of the outdoor unit to operate.

[0108] The first communication circuit 1200 is provided on the indoor unit side, and the second communication circuit 1300 is provided on the outdoor unit side.

[0109] It can be understood that the communication line 700 connects the second port of the first communication circuit 1200 and the first port of the second communication circuit 1300, the second power supply bus 600 is connected to the first port of the first communication circuit 1200, and the second switching circuit 200 is connected to the second port of the second communication circuit 1300. The first communication circuit 1200 and the second communication circuit 1300 establish a communication loop via the communication line 700, the second power supply bus 600 and the second switching circuit 200.

[0110] Here, the first port of the first communication circuit 1200 and the first port of the second communication circuit 1300 are transmitting ports, and the second port of the first communication circuit 1200 and the second port of the second communication circuit 1300 are receiving ports.

[0111] It should be noted that the first communication circuit 1200 includes an energy storage capacitor and a rectifier and voltage divider circuit. The energy storage capacitor is connected to the first power supply bus 500 and the second power supply bus 600. The AC power output by the first power supply bus 500 and the second power supply bus 600 is used to charge the energy storage capacitor through the rectifier and voltage divider circuit. The energy storage capacitor provides communication voltage for the communication circuit.

[0112] It should be noted that, during the startup phase of the air conditioner, since the communication line 700 serves as a temporary power supply line to supply power to the outdoor unit 900 and the second controller 400 is not started, no communication is performed between the first communication circuit 1200 and the second communication circuit 1300; during the operation phase of the air conditioner, the indoor unit 800 supplies power to the outdoor unit 900 via the first power supply bus 500 and the second power supply bus 600, and the first communication circuit 1200 and the second communication circuit 1300 establish a communication loop via the communication line 700, the second power supply bus 600 and the second switching circuit 200. After the indoor unit 800 and the outdoor unit 900 confirm that the working status is normal, the second controller 400 controls the AC load operation of the outdoor unit 900.

[0113] For example, if the control circuit further includes a first positive temperature coefficient resistor 1100 for current limiting the AC power transmitted by the communication line 700 , the first set time length is in direct proportion to the rated resistance value of the first positive temperature coefficient resistor 1100 .

[0114] It should be noted that the rated resistance value of the first positive temperature coefficient resistor 1100 refers to the resistance value of the first positive temperature coefficient resistor 1100 when the working environment temperature is 25° C.

[0115] It can be understood that the first set time is related to the pre-charging efficiency of the supporting capacitor of the power supply circuit 1000 of the outdoor unit 900. The larger the rated resistance value of the first positive temperature coefficient resistor 1100, the lower the power supply voltage of the outdoor unit 900, and the longer the first set time.

[0116] It should be noted that the first set duration is related to the capacitance of the energy storage capacitor on the first communication circuit 1200. During the startup phase of the air conditioner, the indoor unit 800 supplies power to the outdoor unit 900 and charges the energy storage capacitor. The larger the capacitance of the energy storage capacitor, the longer the first set duration.

[0117] Based on test results, an application example of this application provides a calculation formula for the first set duration: T1 = (6-12) * RPTC1_25°C * C2. T1 is the first set duration, in milliseconds; RPTC1_25°C is the rated resistance of the first positive temperature coefficient resistor 1100, in Ω; and C2 is the capacitance of the energy storage capacitor on the first communication circuit 1200, in μF. The first set duration can be determined based on the model of the first positive temperature coefficient resistor 1100 and the energy storage capacitor on the first communication circuit 1200.

[0118] In an application example of the present application, a circuit diagram of an air conditioner is provided, as shown in Figure 10. The air conditioner includes an indoor unit 800, an outdoor unit 900, and a display, wherein the display is used to provide the user with key parameters such as the set temperature, current temperature, and operating mode. The indoor unit 800 includes a first controller 300, a power supply circuit, a first switching circuit 100, a first communication circuit 1200, and an indoor unit load; the outdoor unit 900 includes a second controller 400, a power supply circuit 1000, a second communication circuit 1300, a second switching circuit 200, and an outdoor unit load. The indoor unit load and the outdoor unit load are not specifically shown in Figure 10. The power supply circuit of the indoor unit 800 includes a first main fuse FUSE1, a first rectifier circuit DB1, and a support capacitor C3. The first main fuse FUSE1 provides overcurrent protection for the indoor unit 800. The first rectifier circuit DB1 rectifies the AC power provided by an external power supply into DC power. The support capacitor C3 filters and stabilizes the output power of the first rectifier circuit DB1. The power supply circuit of the indoor unit 800 also includes at least a first switching power supply circuit, which converts the output power of the first rectifier circuit DB1 into control power for the indoor unit 800 and supplies power to DC loads such as the first controller 300; and a first inverter circuit, which inverts the output power of the first rectifier circuit DB1 into AC power and supplies power to the AC loads of the indoor unit 800. The first switching power supply circuit and the first inverter circuit are not specifically shown in Figure 10. The first switching circuit includes a transistor Q3, a first switching element IC3, a first positive temperature coefficient resistor PTC1, and a pull-down resistor R8. The first switching element IC3 comprises a combination of an optocoupler and a thyristor. The first communication circuit includes an energy storage capacitor C2 and a rectifier voltage divider circuit, which includes an anti-reverse diode D2, a voltage regulator diode ZV1, a protective resistor R9, and a voltage divider resistor R10. The indoor unit 800 charges the energy storage capacitor C2 through the rectifier voltage divider circuit, and the energy storage capacitor C2 is used to provide the communication voltage for the communication circuit. The first communication circuit 1200 also includes a first transmitting circuit, a first receiving circuit, a second positive temperature coefficient resistor PTC2 and an anti-reverse diode D1, wherein the first receiving circuit includes a communication optocoupler IC1, a protection resistor R1, a pull-down resistor R2 and a grounding capacitor C1; the first transmitting circuit includes a communication optocoupler IC2, a protection resistor R3, a pull-up resistor R4, a protection resistor R5 and a transistor Q1; the second positive temperature coefficient resistor PTC2 is used to limit the current of the communication loop.

[0119] In addition, the power supply circuit 1000 of the outdoor unit 900 includes a second main fuse FUSE2, a second rectifier circuit DB2, and a support capacitor C4. The second main fuse FUSE2 provides overcurrent protection for the outdoor unit 900. The second rectifier circuit DB2 rectifies the AC power provided by the indoor unit 800 into DC power. The support capacitor C4 filters and stabilizes the output power of the second rectifier circuit DB2. The power supply circuit 1000 of the outdoor unit 900 also includes at least a second switching power supply circuit, which converts the output power of the second rectifier circuit DB2 into control power for the outdoor unit 900 and supplies power to DC loads such as the second controller 400; and a second inverter circuit, which inverts the output power of the second rectifier circuit DB2 into AC power and supplies power to the AC loads of the outdoor unit 900. The second switching power supply circuit and the second inverter circuit are not specifically shown in FIG. 10. The second switching circuit 200 includes a second switch element K1 and a third switch element K2. The second switch element K1 is a normally open relay, and the third switch element K2 is a normally closed relay. The second controller 400 controls the second switch element K1 and the third switch element K2 via a first drive circuit DR1 and a second drive circuit DR2, respectively. The second communication circuit 1300 includes a second transmitting circuit, a second receiving circuit, a protection resistor R11, and an anti-reverse diode D3. The second transmitting circuit includes a communication optocoupler IC4, a protection resistor R13, a pull-up resistor R14, a protection resistor R15, and a transistor Q2. The second receiving circuit includes a communication optocoupler IC5, a protection resistor R12, and a pull-down resistor R11.

[0120] In addition, a first power supply bus L, a second power supply bus N, and a communication line S are provided between the indoor unit 800 and the outdoor unit 900, and the indoor unit 800 and the outdoor unit 900 are reliably grounded.

[0121] In an application example of the present application, a control method for an air conditioner from power on to shutdown is provided in combination with the aforementioned circuit diagram of the air conditioner, as shown in FIG11 . The control method includes:

[0122] Step 1101: Power on the air conditioner.

[0123] It is understandable that after the air conditioner is powered on, the indoor unit 800 is in standby mode, waiting to receive a power-on command; the outdoor unit 900 is in shutdown mode, waiting for the indoor unit 800 to receive a power-on command and then supply power to the outdoor unit 900.

[0124] Step 1102: The indoor unit receives a power-on instruction.

[0125] It is understandable that after the indoor unit 800 receives the power-on instruction from the user, the first controller 300 is awakened and the indoor unit 800 starts to operate.

[0126] In step 1103 , the first controller controls the first switching circuit to be on for a first set time period based on a set on-duty cycle, so that the outdoor unit is powered on and the second controller is started.

[0127] Here, the first controller 300 controls the on / off timing of the transistor Q3 based on a set on-duty cycle, thereby controlling the on / off timing of the first switching element IC3. When the first switching element IC3 is on, the second power bus N and the communication line S are connected, and the indoor unit 800 supplies power to the outdoor unit 900 via the second power bus N and the communication line S. Because the third switching element K2 is closed, the power supply current through the communication line S is passed through the third switching element K2 to the second rectifier circuit DB2. The power supply of the outdoor unit 900 is rectified by the second rectifier circuit DB2 and then charges the support capacitor C4.

[0128] It should be noted that the first controller 300 controls the power supply voltage of the outdoor unit 900 based on controlling the on-off time of the first switching element IC3, thereby achieving soft switching startup and effectively reducing the power supply startup current of the outdoor unit 900.

[0129] It should be noted that, since the second communication circuit 1300 is provided with the anti-reverse diode D3 , the power supply current transmitted via the communication line S will not flow into the second communication circuit 1300 .

[0130] It can be understood that the first positive temperature coefficient resistor PTC1 is used to perform current limiting processing on the communication line S.

[0131] Step 1104: Power on the outdoor unit and start the second controller.

[0132] It is understandable that after the indoor unit 800 charges the support capacitor C4 through the second rectifier circuit DB2 for the first set time T1, the voltage across the support capacitor C4 reaches a preset voltage value, the second switching power supply circuit of the outdoor unit 900 works, and the second controller 400 starts.

[0133] Step 1105: The second controller switches the working state of the second switching circuit to control the second switch element to be closed.

[0134] It should be noted that before step 1105, the working state of the second switching circuit 200 is that the second switch element K1 is disconnected and the third switch element K2 is closed; after the second controller 400 is started, the second switch element K1 is controlled to be closed and the third switch element K2 remains closed. At this time, the indoor unit 800 supplies power to the outdoor unit via the first power supply bus L and the second power supply bus N.

[0135] Step 1106 : In response to starting the second set time, the second controller switches the working state of the second switching circuit and controls the third switch element to be disconnected.

[0136] Here, the second controller 400 switches the operating state of the second switching circuit 200 so that the third switch element K2 is disconnected, and the communication line S no longer serves as a temporary power supply line. The second set duration is related to the closing time of the second switch element K1. The second controller 400 disconnects the third switch element K2 only after ensuring that the second switch element K1 is closed.

[0137] Step 1107: The first controller controls the first switching circuit to be in an off state.

[0138] Here, the first controller 300 stops sending the pulse width modulation signal based on the set on-duty ratio to the transistor Q3 , the first switching element IC3 is in the off state, and thus the first switching circuit 100 is in the off state.

[0139] It should be noted that step 1107 may be executed after step 1106 or simultaneously with step 1106.

[0140] Step 1108: The first controller starts the first communication circuit, and the second controller starts the second communication circuit. The first communication circuit and the second communication circuit establish a communication loop.

[0141] Here, the first controller 300 and the second controller 400 respectively set the transmit pin (TXD) of the first communication circuit 1200 and the transmit pin of the second communication circuit 1300 to a high level, and the communication optocoupler IC2 and the communication optocoupler IC4 are turned on. The first communication circuit 1200 and the second communication circuit 1300 establish a communication loop. The communication loop path is energy storage capacitor C2 → second switch element N → second switch element K1 → communication optocoupler IC5 → communication optocoupler IC4 → protection resistor R11 → anti-reverse diode D3 → communication line S → anti-reverse diode D1 → second positive temperature coefficient resistor PTC2 → communication optocoupler IC1 → communication optocoupler IC2 → energy storage capacitor C2. Among them, energy storage capacitor C2 provides communication voltage for the communication loop.

[0142] Step 1109: After the second controller determines that the communication loop is established, it controls the AC load of the outdoor unit to operate.

[0143] Here, after the communication loop is established, the communication optocoupler IC1 and the communication optocoupler IC5 are turned on, and the receiving pin (RXD) of the first communication circuit 1200 and the receiving pin of the second communication circuit 1300 receive a high-level signal, confirming that the communication loop has been established. The second controller 400 controls the AC load operation of the outdoor unit 900, and a large current is passed through the first power supply bus L and the second power supply bus N.

[0144] Step 1110: The indoor unit receives a shutdown instruction.

[0145] Here, after receiving the shutdown instruction from the user, the indoor unit 800 sends the shutdown instruction to the outdoor unit 900, and the second controller 400 controls the AC load of the outdoor unit 900 to shut down.

[0146] In step 1111, the second controller controls the second switch element to be disconnected and the third switch element to be closed, and the outdoor unit enters a shutdown state.

[0147] Here, after the second controller 400 confirms that the AC load of the outdoor unit 900 is shut down, it executes the shutdown and power-off steps, the second switch element K1 is disconnected, and the third switch element K2 is closed. Since the first switch element IC3 is in the cut-off state at this time, the indoor unit 800 stops supplying power to the outdoor unit 900, and the outdoor unit 900 enters the shutdown state.

[0148] Step 1112: The indoor unit enters the standby state.

[0149] Here, the outdoor unit 900 is in a shutdown state, the communication loop is disconnected, and the first controller 300 confirms that the outdoor unit 900 is in a shutdown state through the first communication circuit 1200. The first controller 300 controls the load of the indoor unit 800 to shut down, and the external power supply supplies power to the indoor unit 800 with a standby current. The indoor unit 800 enters a standby state, waiting for a power-on command from the user.

[0150] It can be understood that any step of the control method of the control circuit in the aforementioned embodiment of the present application can be implemented by configuring the first controller 300 and the second controller 400 of the control circuit.

[0151] The present invention also provides an air conditioner, comprising an indoor unit 800 and an outdoor unit 900. A first power supply bus 500, a second power supply bus 600, and a communication line 700 are provided between the indoor unit 800 and the outdoor unit 900. The air conditioner also includes the control circuit described in the present invention. In this manner, based on the reuse of the second power supply bus 600 and the communication line 700, the indoor unit 800 controls the power supply to the outdoor unit 900 during the startup phase of the air conditioner, and the outdoor unit 900 controls its own power supply during the operation phase of the air conditioner. This prevents the large power supply current of the outdoor unit 900 from flowing into the indoor unit 800 electrical control board, effectively preventing fires in the indoor unit 800 caused by short circuits in the outdoor unit 900 power line and improving the safety of the indoor unit 800. Furthermore, the main relay of the indoor unit 800 is eliminated, reducing the size of the indoor unit 800 electrical control board and saving internal installation space of the indoor unit 800.

[0152] Illustratively, the first power supply bus 500 of the air conditioner in the embodiment of the present application is a live line, and the second power supply bus 600 is a neutral line.

[0153] In an application example of the present application, the first power supply bus 500 of the air conditioner is a neutral line, and the second power supply bus 600 is a live line.

[0154] It can be understood that the control circuit of the embodiment of the present application can implement the aforementioned control method based on the multiplexing of the neutral line and the communication line, or the multiplexing of the live line and the communication line.

[0155] It should be noted that: "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0156] In addition, the technical solutions described in the embodiments of the present application can be arbitrarily combined without conflict.

[0157] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A control circuit for an air conditioner, the air conditioner comprising an indoor unit and an outdoor unit, wherein a first power supply bus, a second power supply bus, and a communication line are provided between the indoor unit and the outdoor unit, the control circuit comprising: a first switching circuit, provided on the indoor unit side and located between the second power supply bus and the communication line, for controlling the connection state between the second power supply bus and the communication line on the indoor unit side; a second switching circuit, provided on the outdoor unit side and located between the second power supply bus and the communication line, for controlling the connection state between the second power supply bus and the power supply line of the outdoor unit, and controlling the connection state between the communication line and the power supply line of the outdoor unit; a first controller, disposed at the indoor unit side, connected to the first switching circuit, and configured to control a voltage value between the first power supply bus and the communication line based on adjustment of a conduction duty cycle of the first switching circuit; The second controller is arranged at the outdoor unit side, connected to the second switching circuit, and configured to control the working state of the second switching circuit.

2. The control circuit according to claim 1, wherein: The first switching circuit includes: a first switch element, configured to control a connection state between the second power supply bus and the communication line; the first switch element being connected to the second power supply bus and the communication line; A switch tube is used to control the on-off state of the first switch element based on the conduction duty cycle.

3. The control circuit according to claim 1, wherein: The second switching circuit includes: a second switching element, configured to control a connection state between the second power supply bus and a power supply line of the outdoor unit; The third switch element is used to control the connection state between the communication line and the power supply line of the outdoor unit.

4. The control circuit according to claim 3, wherein: The second switching element is a normally open relay, and the third switching element is a normally closed relay.

5. The control circuit according to claim 1, wherein: The control circuit further includes: A first positive temperature coefficient resistor is used to perform current limiting processing on the communication line; the first positive temperature coefficient resistor is arranged in the first switching circuit or the second switching circuit.

6. The control circuit according to claim 1, wherein: The control circuit further includes: a first communication circuit, provided at the indoor unit side, for sending a communication signal of the indoor unit to the outdoor unit, and receiving a communication signal from the outdoor unit; a second communication circuit, provided at the outdoor unit side, for sending a communication signal from the outdoor unit to the indoor unit and receiving a communication signal from the indoor unit; The first port of the first communication circuit is connected to the second port of the second communication circuit via the communication line, and the second port of the first communication circuit is connected to the first port of the second communication circuit via the second power supply bus and the second switching circuit.

7. A control method for a control circuit according to any one of claims 1 to 6, comprising: In response to a power-on instruction, the first controller controls the first switching circuit to be on for a first set time period based on a set on-duty cycle, so that the outdoor unit is powered on and the second controller is started; The second controller switches the working state of the second switching circuit so that the second power supply bus is connected to the power supply line of the outdoor unit; The second controller switches the working state of the second switching circuit in response to starting the second set time, so that the communication line is disconnected from the power supply line of the outdoor unit; The first controller controls the first switching circuit to be in an off state.

8. The method according to claim 7, wherein: The first controller controls the first switching circuit to be turned on for a first set duration based on a set on-duty cycle, including: The first controller controls the voltage value between the first power supply bus and the communication line based on a set conduction duty cycle; The setting of the on-duty cycle includes: The set on-duty cycle is the first duty cycle; or the set on-duty cycle gradually increases from the second duty cycle to the third duty cycle and then remains unchanged.

9. The method according to claim 7, wherein: If the control circuit further includes a first positive temperature coefficient resistor for current limiting the alternating current transmitted by the communication line, the first set time length is in direct proportion to the rated resistance value of the first positive temperature coefficient resistor.

10. The method according to claim 7, wherein: The method further comprises: The first controller starts a first communication circuit, the second controller starts a second communication circuit, and the first communication circuit and the second communication circuit establish a communication loop; After the second controller determines that the communication loop is established, it controls the AC load of the outdoor unit to operate; Wherein, the first communication circuit is arranged on the indoor unit side, and the second communication circuit is arranged on the outdoor unit side.

11. A control circuit according to any one of claims 1 to 6, wherein the first controller and the second controller are configured to perform the steps of the method according to any one of claims 7 to 10.

12. An air conditioner, comprising an indoor unit and an outdoor unit, wherein a first power supply bus, a second power supply bus and a communication line are provided between the indoor unit and the outdoor unit, and the air conditioner further comprises the control circuit according to claim 11.

13. The air conditioner according to claim 12, wherein The first power supply bus is a live wire, and the second power supply bus is a neutral wire; or the first power supply bus is a neutral wire, and the second power supply bus is a live wire.

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