Air conditioner

Abstract

The air conditioner comprises an input power supply, a buffer starting module, a rectification module, a switching power supply module, a detection module and a controller, and the controller is used for receiving a voltage feedback signal when the air conditioner is powered on and in a standby state, determining a corresponding actual direct-current bus voltage according to the voltage feedback signal and outputting the actual direct-current bus voltage. And on the basis of a comparison result of the actual direct current bus voltage, a preset minimum working voltage threshold value and a return difference voltage threshold value, the on-off state of the relay is controlled to switch a conduction path of the buffer starting module, so that the power supply state of the input power supply to the rectification module is adjusted, and the preset minimum working voltage threshold is the minimum input voltage required by the switching power supply module, so that the operational voltage range of the controller is effectively widened while the standby power consumption is remarkably reduced. And moreover, the energy-saving performance, the reliability and the wide voltage adaptability can be considered without additionally arranging complex elements, so that the overall cost of the system is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air conditioners, in particular to an air conditioner. BACKGROUND

[0002] In the prior art, the low-power processing mode of an air conditioner mainly depends on two schemes. The first scheme is to control a main power relay in a normally closed manner, that is, the main power circuit is not provided with any control logic, and the relay always remains closed, so that the switching power supply in the main power supply continuously works to convert alternating current into low-voltage direct current for supplying the standby circuit of the controller. Although this design is simple in structure and low in cost, the power conversion process always exists, resulting in great energy loss and significantly increasing the power consumption in the standby state.

[0003] The second scheme is to achieve the disconnection control of the relay by adding an auxiliary power supply. When the air conditioner enters the standby state, the control system cuts off the main power supply through an additional relay driving circuit and provides an additional power supply to the controller to provide the direct current required for maintaining the standby function of the controller. This scheme can effectively reduce the no-load loss of the main power supply and reduce the overall standby power consumption, and the control logic is relatively clear. However, since an auxiliary power supply module and related control circuit need to be additionally configured, the hardware cost and circuit complexity of the system are increased. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the purpose of the present application is to provide an air conditioner.

[0005] The air conditioner provided by the present application comprises: an input power supply for providing an alternating input voltage; a buffer starting module, the buffer starting module comprising a PTC (Positive Temperature Coefficient) resistor and a relay connected in parallel, one end of the PTC resistor and one end of the relay being connected with the input power supply respectively; a rectifier module, one end of the rectifier module being connected with the other end of the PTC resistor and the other end of the relay respectively, for rectifying the alternating input voltage into a direct current bus voltage; a switching power supply module connected with the other end of the rectifier module, for converting the direct current bus voltage into low-voltage direct current to supply power to the controller and the detection module; the detection module connected with the other end of the rectifier module, for detecting the direct current bus voltage and generating a corresponding voltage feedback signal; The controller is connected with the relay, the switching power supply module and the detection module respectively, and is configured to receive the voltage feedback signal when the air conditioner is powered on and in the standby state, determine the actual DC bus voltage corresponding to the voltage feedback signal, and control the on-off state of the relay based on the comparison result of the actual DC bus voltage, a preset minimum working voltage threshold and a hysteresis voltage threshold, so as to switch the conduction path of the buffer starting module, thereby adjusting the power supply state of the input power supply to the rectifier module, wherein the preset minimum working voltage threshold is the minimum input voltage required for the switching power supply module to work.

[0006] According to the air conditioner provided by the embodiment of the present application, when the air conditioner is powered on and in the standby state, the voltage feedback signal detected by the detection module is received, the actual DC bus voltage corresponding to the voltage feedback signal is determined, and the actual DC bus voltage is compared with the preset minimum working voltage threshold and the hysteresis voltage threshold, and the on-off state of the relay is controlled according to the comparison result, so as to switch the conduction path of the buffer starting module according to the closed state or the conduction state of the relay, thereby adjusting the power supply state of the input power supply to the rectifier module. In this way, not only can the controller itself be reliably powered on and continuously operated under abnormal working conditions such as grid voltage fluctuation or low input voltage, but also the power supply mode can be automatically switched according to the voltage condition in the standby state, thereby significantly reducing the standby power consumption and effectively widening the operating voltage range of the controller. Moreover, without additional complex elements, the energy saving, reliability and wide voltage adaptability can be considered, thereby reducing the overall system cost.

[0007] In addition, the air conditioner provided by the embodiment of the present application can also have the following additional technical features: Further, before receiving the voltage feedback signal, the controller is configured to control the relay to be disconnected, so that the AC input voltage provided by the input power supply supplies power to the rectifier module through the path where the PTC resistor is located, to establish the DC bus voltage, thereby powering on the switching power supply module, the detection module and the controller and entering the normal working state.

[0008] The above technical solution has the following advantages or beneficial effects: not only the soft start and surge suppression are realized, but also the system can establish the necessary power supply voltage and complete the bootstrap power-on in the case that the main path where the relay is located is not conducted, thereby improving the reliability of the air conditioner system.

[0009] Further, before controlling the on-off state of the relay based on the comparison result of the actual DC bus voltage, the preset minimum working voltage threshold and the hysteresis voltage threshold, the controller is configured to control the relay to remain in the closed state for a first preset time.

[0010] The technical solution has the advantages or beneficial effects that: avoiding misjudgment caused by power transient fluctuation, thereby improving the reliability and control accuracy of system startup.

[0011] Further, when controlling the on-off state of the relay based on the comparison result of the actual DC bus voltage and the preset minimum working voltage threshold and the hysteresis voltage threshold, the controller is configured to: obtain a first duration of the relay being closed; when the first duration is greater than the first preset time, and the actual DC bus voltage is less than or equal to the sum of the preset minimum working voltage threshold and the hysteresis voltage threshold, determine whether the actual DC bus voltage is less than the preset minimum working voltage threshold; if yes, control the relay to remain in the closed state.

[0012] The technical solution has the advantages or beneficial effects that: ensuring that the input power continuously supplies power through the low-resistance path where the relay is located, avoiding further voltage drop caused by PTC resistance voltage drop, thereby ensuring stable operation of the switching power supply module, maintaining the continuity of the controller's own power supply, thereby effectively preventing the system from misoperation during voltage transient fluctuation or initial power-on, and improving the running stability.

[0013] Further, when controlling the on-off state of the relay based on the comparison result of the actual DC bus voltage and the preset minimum working voltage threshold and the hysteresis voltage threshold, the controller is further configured to: when the first duration is greater than the first preset time, and the actual DC bus voltage is greater than the sum of the preset minimum working voltage threshold and the hysteresis voltage threshold, control the relay to be opened, and store the currently detected actual DC bus voltage as a maximum bus voltage.

[0014] The technical solution has the advantages or beneficial effects that: significantly reducing the standby energy consumption of the whole machine and the adaptability and reliability of the air conditioner in the environment of low grid voltage, thereby improving the accuracy of circuit control.

[0015] Further, after controlling the relay to be opened and storing the currently detected actual DC bus voltage as a maximum bus voltage, the controller is configured to: obtain a second duration of the relay being opened, and a new maximum bus voltage during the relay being opened; and control the on-off state of the relay according to the second duration and the new maximum bus voltage.

[0016] The technical solution has the advantages or beneficial effects that: avoiding frequent misoperation, achieving dynamic adaptation to grid changes while maintaining energy-saving effect, and improving the reliability and intelligent level of the system in complex power consumption environment.

[0017] Further, in controlling the on-off state of the relay according to the second duration and the new bus voltage maximum value, the controller is configured to: determine a difference between the new bus voltage maximum value and the back-off voltage threshold value; and control the relay to close when the new bus voltage maximum value is less than the difference and the second duration is greater than a second preset time.

[0018] The above technical solution has the following advantages or beneficial effects: it can effectively avoid misoperation caused by instantaneous voltage fluctuation or temporary power failure, prevent the relay from frequently turning on and off, and improve the anti-interference ability and operation reliability of the system. At the same time, by dynamically adjusting the voltage threshold for recovery closing based on the new bus voltage maximum value, the system can adapt to different power grid environments and realize precise power management, ensuring stability while maximizing energy saving effect.

[0019] Further, in controlling the relay to close when the new bus voltage maximum value is less than the difference and the second duration is greater than a second preset time, the controller is configured to: obtain a third duration for which the relay is closed; and control the relay to open after the third duration reaches a third preset time.

[0020] The above technical solution has the following advantages or beneficial effects: it can realize the automatic reset function after the relay is closed, avoid additional energy consumption caused by long-term closing of the relay, and enable the system to intelligently recover and save energy again after dealing with voltage fluctuations, thereby ensuring operation reliability under low-voltage conditions and taking into account energy efficiency optimization of long-term standby, improving the adaptive ability and comprehensive performance of the air conditioner in complex power grid environments.

[0021] Further, in obtaining the new bus voltage maximum value during the period when the relay is opened, the controller is configured to: obtain a first voltage feedback signal during the period when the relay is opened; determine a first actual direct current bus voltage according to the first voltage feedback signal; and update the first actual bus voltage to the new bus voltage maximum value and store it when the first actual direct current bus voltage is greater than the bus voltage maximum value.

[0022] The above technical solution has the following advantages or beneficial effects: it realizes adaptive learning ability for power supply environment, enhances the intelligence and reliability of the control logic, and avoids misjudgment caused by fixed threshold.

[0023] Further, when the controller controls the on-off state of the relay based on the comparison result of the actual DC bus voltage with the preset minimum operating voltage threshold and the hysteresis voltage threshold, the controller is configured to: acquire the actual DC bus voltage of the relay during the opening period or the closing period in real time, and update the current actual DC bus voltage as the latest bus voltage maximum value and store it when it is detected that the current actual DC bus voltage is greater than the stored bus voltage maximum value.

[0024] The above technical solution has the following advantages or beneficial effects: intelligent tracking of the power supply state is achieved, the accuracy of relay on-off control and the stability of system operation are improved, and the adaptability of standby energy-saving strategy is enhanced.

[0025] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0026] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the accompanying drawings, in which: Figure 1 is a structural schematic diagram of an air conditioner according to an embodiment of the present application; Figure 2 is a structural schematic diagram of a controller according to an embodiment of the present application; Figure 3 is a structural schematic diagram of an air conditioner according to another embodiment of the present application; Figure 4 is a circuit schematic diagram of an air conditioner according to an embodiment of the present application; Figure 5 is a flowchart of a control method of an air conditioner according to an embodiment of the present application; Figure 6 is a flowchart of controlling the on-off state of a relay according to an embodiment of the present application; Figure 7 is a flowchart of controlling the on-off state of a relay according to another embodiment of the present application; Figure 8 is a flowchart of determining a new bus voltage maximum value according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0028] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0029] The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0030] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] The embodiment of the present application provides an air conditioner 10, referring to Figure 1 The air conditioner 10 includes a refrigeration system for heat exchange with indoor air to achieve refrigeration or heating requirements.

[0032] The refrigeration system includes a compressor, a condenser, an electronic expansion valve and an evaporator. In the present application, the air conditioner 10 performs the refrigeration cycle of the air conditioner 10 by using the compressor, the condenser, the electronic expansion valve and the evaporator. The refrigeration cycle includes a series of processes, involving compression, condensation, expansion and evaporation, and supplies refrigerant to the air that has been adjusted and heat exchanged.

[0033] The compressor compresses refrigerant gas in a high-temperature and high-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0034] The electronic expansion valve expands the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure liquid phase. The evaporator evaporates the refrigerant expanded in the electronic expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor.

[0035] The evaporator can achieve a refrigeration effect by exchanging heat with a material to be cooled using latent heat of evaporation of the refrigerant. Throughout the cycle, the air conditioner 10 can adjust the temperature of the indoor space.

[0036] The outdoor unit 2 of the air conditioner 10 refers to a portion of the refrigeration cycle including the compressor and the outdoor heat exchanger, the indoor unit 1 of the air conditioner 10 includes the indoor heat exchanger, and the electronic expansion valve can be provided in the indoor unit 1 or the outdoor unit 2.

[0037] The indoor heat exchanger and the outdoor heat exchanger serve as a condenser or an evaporator. When the indoor heat exchanger serves as a condenser, the air conditioner 10 serves as a heater in a heating mode, and when the indoor heat exchanger serves as an evaporator, the air conditioner 10 serves as a cooler in a cooling mode.

[0038] The air conditioner 10 in the present disclosure includes an indoor unit 1 and an outdoor unit 2, which can be provided as an all-in-one or a split unit. The indoor unit 1 can be provided as a wall-mounted, ceiling-mounted, ducted, etc., and the indoor unit 1 is installed on the top or top of the indoor room.

[0039] Reference Figure 1 Taking the indoor hanging machine as an example, the indoor hanging machine is usually installed at a position such as an indoor wall, and the indoor cabinet machine (not shown in the figure) is also one of the indoor unit 1 forms of the indoor unit 1.

[0040] Taking the split unit as an example, the air conditioner 10 includes an indoor unit 1 and an outdoor unit 2, wherein the outdoor unit 2 is usually provided outdoors and is used for indoor environment heat exchange.

[0041] In addition, as shown in the figure, the air conditioner 10 is provided with a controller 71 to control the operation of each component in the air conditioner 10, so that each component of the air conditioner 10 operates to achieve each predetermined function of the air conditioner 10. Among them, the control device 200 is also attached in the air conditioner 10, and the control device 200 is specifically provided as a remote controller, which has the function of communicating with the controller 71 by using infrared rays or other communication methods, for example. The remote controller is used for the user to control various controls of the air conditioner 10, so as to realize the interaction between the user and the air conditioner 10.

[0042] In this embodiment of the invention, the indoor unit 1 of the air conditioner 10 is located at the top or upper part of the room. Generally, the installation height of the indoor unit 1 is higher than the user's activity area. The indoor unit 1 includes a return air vent and an air outlet that communicate with the room. Indoor air passes through the return air vent into the indoor unit 1 and flows back into the room through the air outlet.

[0043] The refrigerant circulation loop in this invention allows the refrigerant to circulate within a circuit consisting of a compressor, condenser, electronic expansion valve, and evaporator. One of the condenser and evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger. The indoor heat exchanger exchanges heat with the air inside the indoor unit 1, and the outdoor unit 2 heat exchanger exchanges heat with the air inside the outdoor unit 2, thereby fulfilling the cooling or heating requirements of the air conditioner 10.

[0044] The indoor unit 1 also includes an indoor fan, which is located near the return air vent or the air outlet of the indoor heat exchanger. It is used to deliver the heat-exchanged air to the room. The indoor fan has multiple speed settings to change the airflow speed at the air outlet.

[0045] An air guide plate is installed at the air outlet. By changing its relative rotation angle with the air outlet, the air guide plate adjusts the direction of the airflow through the air outlet, thereby affecting the stratification of indoor air temperature.

[0046] In the embodiment shown in this invention, the air conditioner 10 further includes a controller 71, which is a device that can generate operation control signals according to instruction operation codes and timing signals to instruct the air conditioner 10 to execute control commands. For example, in response to a power-on or power-off command issued by a user, the controller 71 can perform an operation related to the object selected by the power-on or power-off command.

[0047] This invention also provides a hardware structure diagram of the controller 71, as shown in the embodiment. Figure 2 As shown, the controller 71 includes a processor 83, and optionally, a memory 82 and a communication interface 84 connected to the processor 83. The processor 83, memory 82, and communication interface 84 are connected via a bus 81.

[0048] The processor 83 can be a central processing unit (CPU), a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microprocessor, a microcontroller 718, a programmable logic device (PLD), or any combination thereof. The processor 83 can also be other devices with processing capabilities such as a circuit, a device, or a software module. The processor 83 can also include multiple CPUs, and the processor 83 can be a single CPU processor 83 or a multi-CPU processor 83. The processor 83 herein can refer to one or more devices, circuits, or processing cores for processing data (e.g., computer program instructions).

[0049] The memory 82 can be a read only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read only memory (EEPROM), a compact disc read only memory (CD ROM) or other optical disk storage, a magnetic disk storage or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and that can be accessed by a computer, without limitation. The memory 82 can exist independently or be integrated with the processor 83. The memory 82 can include computer program code. The processor 83 is configured to execute the computer program code stored in the memory 82, thereby implementing the control method of the air conditioner provided by the embodiments of the present application.

[0050] The communication interface 84 can be configured to communicate with other devices or communication networks (e.g., Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc.). The communication interface 84 can be a module, a circuit, a transceiver, or any device capable of communication.

[0051] The bus 81 can be a peripheral component interconnect (PCI) bus 81 or an extended industry standard architecture (EISA) bus 81, etc. The bus 81 can be divided into an address bus 81, a data bus 81, a control bus 81, etc. For ease of representation, Figure 2 Only one thick line is used to represent the bus 81 in the figure, but it does not mean that there is only one bus 81 or only one type of bus 81.

[0052] The following will be described with reference to Figure 3 An air conditioner according to an embodiment of the application.

[0053] Figure 3 is a structural schematic diagram of an air conditioner according to an embodiment of the application. As shown in Figure 3 An air conditioner 10 includes an input power supply 11, a buffer starting module 12, a rectifier module 13, a switching power supply module 14, a detection module 15, and a controller 71.

[0054] As shown in Figure 4 The input power supply 11 is configured to provide an alternating current input voltage. The buffer starting module 12 includes a PTC resistor and a relay K1 connected in parallel. One end of the PTC resistor and one end of the relay K1 are connected to the input power supply 11. One end of the rectifier module 13 is connected to the other end of the PTC resistor and the other end of the relay K1, respectively, for rectifying the alternating current input voltage into a direct current bus voltage. The switching power supply module 14 is connected to the other end of the rectifier module 13, for converting the direct current bus voltage into a low-voltage direct current to supply power to the controller 71 and the detection module 15. The detection module 15 is connected to the other end of the rectifier module 13, for detecting the direct current bus voltage and generating a corresponding voltage feedback signal.

[0055] The controller 71 is connected to the relay K1, the switching power supply module 14, and the detection module 15, respectively. When the air conditioner 10 is powered on and in a standby state, the controller 71 receives the voltage feedback signal, determines a corresponding actual direct current bus voltage according to the voltage feedback signal, and controls the on-off state of the relay K1 based on a comparison result of the actual direct current bus voltage, a preset minimum working voltage threshold, and a hysteresis voltage threshold, to switch a conduction path of the buffer starting module 12, thereby adjusting a power supply state of the input power supply 11 to the rectifier module 13. The preset minimum working voltage threshold is the minimum input voltage required for the switching power supply module 14 to work.

[0056] In an embodiment, as Figure 4As shown, the input power supply 11 provides an AC input voltage for the entire circuit, which is connected to the buffer starting module 12 composed of a PTC resistor and a relay K1 in parallel. The PTC resistor has a positive temperature coefficient characteristic, with a high cold-state resistance, for example, set to about 100Ω, which can effectively suppress the inrush current at the initial power-on stage, preventing damage to the rectifier bridge and electrolytic capacitor due to transient high current; the relay K1 acts as a main path switch, whose on-off state is dynamically controlled by the controller 71 according to the system operating state. The rectifier module 13 rectifies the AC input voltage from the buffer starting module 12 into a DC bus voltage.

[0057] One end of the switching power supply module 14 is connected to the other end of the rectifier module 13, which can receive the DC bus voltage output by the rectifier module 13 and convert it into low-voltage DC (such as 5V or 3.3V) to provide stable operating power for the controller 71 and the detection module 15, ensuring continuous operation of the system.

[0058] The detection module 15 is connected to the other end of the rectifier module 13, which can sample the DC bus voltage at the other end of the rectifier module 13 in real time and generate a voltage feedback signal proportional to it, which is transmitted to the controller 71, ensuring that the controller 71 can accurately obtain the voltage information of the input power supply 11 within the safe voltage range.

[0059] After receiving the voltage feedback signal, the controller 71 reads it through analog-to-digital conversion, and calculates the actual DC bus voltage corresponding to it according to the pre-set voltage division ratio, thereby realizing real-time monitoring of the voltage of the input power supply 11, so that the controller 71 can dynamically grasp the power supply state. On this basis, the controller 71 compares the actual DC bus voltage value with the pre-set minimum operating voltage threshold and the hysteresis voltage threshold. The pre-set minimum operating voltage threshold refers to the minimum input voltage (for example, 60V) required for the switching power supply module 14 to work continuously and stably, if the DC bus voltage is lower than this value, the switching power supply module 14 may not start normally or the output may be unstable, causing the controller 71 and the detection module 15 and other core components to lose power; the introduction of the hysteresis voltage threshold is to prevent the system from frequently oscillating near the critical voltage, improving control stability.

[0060] The controller 71 dynamically controls the on or off state of the relay K1 based on the comparison result. For example, when the comparison result indicates that the current power supply condition is good and the energy saving operation condition is met, the relay K1 is controlled to be off. At this time, the on path of the buffer starting module 12 is switched to the path formed by the PTC resistor, and the input power supply 11 continuously supplies power to the rectifier module 13 through the PTC resistor. Since the load current is small in the standby state, the voltage drop on the PTC resistor is limited, and sufficient DC bus voltage can be maintained to ensure stable operation of the switching power supply module 14. In this state, the drive coil of the relay K1 no longer consumes power (for example, the power consumption is about 0.96 W), thereby effectively reducing the standby power consumption of the whole machine and achieving the energy saving goal.

[0061] When the comparison result indicates that the current power supply capability is insufficient, the controller 71 re-closes the relay K1 and switches to low-resistance path power supply, that is, the on path is switched from the path where the PTC resistor is located to the low-resistance path where the relay K1 is located. This switching eliminates the voltage drop and power loss on the PTC resistor, so that more input voltage is effectively transmitted to the rectifier module 13, thereby increasing the DC bus voltage and ensuring that it is always higher than the minimum operating voltage requirement of the switching power supply module 14. Through the above mechanism, the controller 71 precisely controls the on path of the buffer starting module 12, not only ensures that the controller 71 itself can be reliably powered on and continuously operated under abnormal working conditions such as power grid voltage fluctuation or low input voltage, but also automatically switches the power supply mode according to the voltage condition in the standby state, significantly reduces the standby power consumption, and effectively widens the operating voltage range of the controller 71. Moreover, without additional complex components, energy saving, reliability and wide voltage adaptability can be considered, thereby reducing the overall cost of the system.

[0062] In an embodiment of the present application, before receiving the voltage feedback signal, the controller 71 is configured to control the relay K1 to be off, so that the AC input voltage provided by the input power supply 11 supplies power to the rectifier module 13 through the path where the PTC resistor is located, to establish the DC bus voltage, so that the switching power supply module 14, the detection module 15 and the controller 71 are powered on and enter the normal working state.

[0063] In an embodiment, before receiving the voltage feedback signal, the controller 71 is configured to perform a power supply establishment process in the power-on initialization phase. Specifically, when the air conditioner 10 is powered on for the first time or is re-powered on, the controller 71 has not obtained stable power supply, and the internal logic is in the reset or standby state. At this time, the controller 71 controls the relay K1 to be off, so that the AC input voltage provided by the input power supply 11 flows to the rectifier module 13 through the path formed by the PTC resistor.

[0064] With the current continuously supplying the rectifier module 13 through the PTC resistor, the AC input voltage is converted into DC bus voltage by the rectifier module 13, and the filter electrolytic capacitor in the rectifier module 13 is charged, and a stable DC bus voltage is gradually established. When the DC bus voltage rises above the starting threshold of the switching power supply module 14, the switching power supply module 14 starts to work normally and converts it into low-voltage DC power to supply power to the detection module 15 and the controller 71 in turn.

[0065] Once the controller 71 obtains a stable working power supply, the power-on process is completed, and the normal working state of the controller 71 is entered. At this time, the internal analog-to-digital converter, control logic unit and other functional modules of the controller 71 have been activated, and have the ability to receive and process the voltage feedback signal from the detection module 15. Therefore, in the initial stage, by controlling the relay K1 to be disconnected and relying on the PTC resistor for power supply, not only the soft start and surge suppression are realized, but also the necessary power voltage is ensured to be established and the bootstrap power-on is completed in the case that the main path where the relay K1 is located is not turned on, thereby improving the reliability of the air conditioner 10 system.

[0066] In an embodiment of the present application, before controlling the on-off state of the relay K1 based on the comparison result of the actual DC bus voltage and the preset minimum working voltage threshold and the hysteresis voltage threshold, the controller 71 is configured to control the relay K1 to remain in the closed state for a first preset time.

[0067] In the embodiment, after the system is powered on and works normally, the relay K1 is first controlled to remain in the closed state for a first preset time, so that after ensuring that the relay K1 is closed, the input power supply 11 stably supplies power to the rectifier module 13 through the low-resistance path where the relay K1 is located, and the DC bus voltage is fully established and enters a steady state. During this period, the switching power supply module 14, the detection module 15 and the controller 71 itself complete the power-on initialization, and the voltage feedback signal tends to be stable, avoiding misjudgment caused by transient fluctuations during power-on. After the first preset time ends, the controller 71 performs logical judgment according to the stable voltage feedback signal, and starts the intelligent on-off control of the relay K1, thereby improving the reliability and control accuracy of system startup.

[0068] In an embodiment of the present application, when the on-off state of the relay K1 is controlled based on the comparison result of the actual DC bus voltage and the preset minimum working voltage threshold and the hysteresis voltage threshold, the controller 71 is configured to obtain the first duration of the relay K1 being closed; when the first duration is greater than the first preset time, and the actual DC bus voltage is less than or equal to the sum of the preset minimum working voltage threshold and the hysteresis voltage threshold, it is judged whether the actual DC bus voltage is less than the preset minimum working voltage threshold; if yes, the relay K1 is controlled to remain in the closed state.

[0069] Wherein, for example, the actual DC bus voltage is recorded as Vdc, the preset minimum operating voltage threshold is recorded as V_low_on and V_low_on = 60V, and the hysteresis voltage threshold is recorded as V_delta and V_delta = 20V.

[0070] In an embodiment, the controller 71 first acquires the duration of the current closed state of the relay K1, recorded as the first duration. When the first duration exceeds a first preset time, the subsequent voltage judgment process is allowed to enter, so as to avoid misjudgment when the relay K1 is just closed and the system has not yet stabilized.

[0071] Specifically, when the first duration is greater than the first preset time, and the actual DC bus voltage Vdc is detected to be less than or equal to the sum of the preset minimum operating voltage threshold V_low_on and the hysteresis voltage threshold V_delta, i.e. Vdc V_low_on + V_delta, the controller 71 further judges whether Vdc is lower than V_low_on, for example, V_low_on = 60V and V_delta = 20V, so that the sum of the preset minimum operating voltage threshold V_low_on and the hysteresis voltage threshold V_delta is 80V. If Vdc 80V and at the same time Vdc < 60V, it indicates that the current DC bus voltage has approached or is lower than the minimum input voltage required by the switching power supply module 14 to maintain normal operation, and there is a risk of system power loss. At this time, the controller 71 immediately controls the relay K1 to remain closed, ensuring that the input power supply 11 continuously supplies power through the low-resistance path where the relay K1 is located, avoiding further voltage drop due to PTC resistance voltage drop, thereby ensuring stable operation of the switching power supply module 14 and maintaining the continuity of the power supply of the controller 71 itself, thereby effectively preventing system misoperation during voltage transient fluctuation or initial power-on, and improving the operation stability.

[0072] In an embodiment of the present application, when controlling the on-off state of the relay K1 based on the comparison result of the actual DC bus voltage and the preset minimum operating voltage threshold and the hysteresis voltage threshold, the controller 71 is further configured to: when the first duration is greater than the first preset time, and the actual DC bus voltage is greater than the sum of the preset minimum operating voltage threshold and the hysteresis voltage threshold, the relay K1 is controlled to be opened, and the currently detected actual DC bus voltage is stored as the maximum bus voltage.

[0073] In an embodiment, when the controller 71 detects that the first duration of the relay K1 being closed is greater than the first preset time, it indicates that the system has completed the power-on stabilization process and enters the normal operation state; at this time, if the actual DC bus voltage Vdc is greater than the sum of the preset minimum operating voltage threshold V_low_on and the hysteresis voltage threshold V_delta, i.e. Vdc > V_low_on + V_delta = 80V, it indicates that the current power supply is sufficient. Under this condition, the controller 71 determines that the system can safely enter the energy-saving mode, and then controls the relay K1 to be opened, so that the current path of the input power supply 11 is switched to the current-limiting path composed of the PTC resistor.

[0074] For example, the PTC resistor has a cold resistance of 100Ω, and the load current in the standby state is about 0.1A. When the relay K1 is opened, the current is supplied through the PTC resistor, and the voltage drop across the PTC resistor is 100Ω x 0.1A = 10V. Since the air conditioner 10 is in the standby state, the load is light, and the current flowing through the PTC resistor is small (for example, 0.1A), the voltage drop generated by the PTC resistor is limited (for example, 100Ω x 0.1A = 10V), and the DC bus voltage output by the rectifier module 13 can still be maintained above the minimum operating voltage of the switching power supply module 14, ensuring the continuous and stable operation of the system.

[0075] When the actual DC bus voltage is higher than 80V, the relay K1 is controlled to be opened, and only the PTC resistor is used to charge the rectified electrolytic capacitor to maintain the operation of the switching power supply module 14. For example, when the relay K1 is operating, it requires a working voltage and current of 12V and 80mA, which generates standby power consumption of 0.96W. After the relay K1 is controlled to be opened, the driving coil no longer consumes driving power (i.e. 12V x 80mA = 0.96W), and the standby power consumption is completely eliminated, thereby significantly reducing the standby power consumption of the entire machine.

[0076] To ensure the normal operation of the switching power supply module 14, the DC bus voltage after rectification through the PTC resistor needs to be at least 60V, but considering the hysteresis control, the actual DC bus voltage needs to be maintained above 80V. Since the standby load is light, the DC bus voltage after rectification and filtering is close to the peak value of the AC input voltage, and therefore the minimum effective value of the AC input voltage required is: 10V + (80V / √2) ≈ 10V + 56.58V = 66.58V.

[0077] In addition, when the relay K1 is closed, the PTC resistor is short-circuited and has no additional voltage drop. At this time, only the DC bus voltage after rectification needs to be greater than or equal to 80V, and the minimum effective value of the AC input voltage required is: 80V / √2 ≈ 56.58V.

[0078] Therefore, by closing the relay K1 under low voltage condition, the system can still operate stably when the AC input voltage is as low as about 56.58V, which is 10V wider than the lower limit of 66.58V of the PTC path, significantly improving the adaptability and reliability of the air conditioner in the environment of low grid voltage.

[0079] Meanwhile, while performing the relay K1 opening operation, the controller 71 records and stores the current detected actual DC bus voltage value as the bus voltage maximum value. This value represents the highest voltage level reached by the system during the last main path conduction period, serving as a reference for subsequent voltage drop judgment. Through this mechanism, the system not only realizes automatic energy saving when the power supply is good, but also establishes a dynamic voltage reference, providing a reliable basis for subsequent judgment of whether to re-close the relay (for example, when the grid voltage drops to the critical value), thereby improving the accuracy of circuit control.

[0080] In an embodiment of the present application, after controlling the relay K1 to open and storing the current detected actual DC bus voltage as the bus voltage maximum value, the controller 71 is configured to: obtain a second duration of the relay K1 being open, and a new bus voltage maximum value during the relay K1 being open; and control the on-off state of the relay K1 according to the second duration and the new bus voltage maximum value.

[0081] In an embodiment, the controller 71 starts timing the second duration of the relay K1 being open, while continuing to sample the DC bus voltage in real time through the detection module 15 and updating the system state according to the voltage feedback signal. During this period, the controller 71 dynamically records the new bus voltage maximum value appearing in the open phase, which may be higher or lower than the initially stored bus voltage maximum value due to grid fluctuations.

[0082] The controller 71 controls the on-off state of the relay K1 based on the second duration and the new bus voltage maximum value to avoid frequent false actions, achieving dynamic adaptation to grid changes while maintaining energy saving effects, and improving the reliability and intelligent level of the system in complex power consumption environments.

[0083] In an embodiment of the present application, when controlling the on-off state of the relay K1 according to the second duration and the new bus voltage maximum value, the controller 71 is configured to: determine a difference between the new bus voltage maximum value and the drop voltage threshold value; and control the relay K1 to close when the new bus voltage maximum value is less than the difference and the second duration is greater than a second preset time.

[0084] In an embodiment, the controller 71 first calculates the difference between the new bus voltage maximum value and the preset back-off voltage threshold V_delta, for example, the new bus voltage maximum value is denoted as V1, and the difference is denoted as V1-V_delta. Then =V1-V_delta.

[0085] When the controller 71 detects that the actual DC bus voltage Vdc is lower than the difference V1-V_delta At the same time, the second duration during which the relay K1 is open has been greater than the second preset time, it indicates that the air conditioner 10 has been running in the PTC resistance power supply mode for a long enough time, and the grid voltage has been continuously low to a level that may threaten the normal work of the switching power supply module 14. At this time, the controller 71 determines that there is a risk of power loss if the open state of the relay K1 is continued to be maintained, and then controls the relay K1 to be closed, so as to switch the power supply path from the PTC resistance path back to the low resistance path where the relay K1 is located, eliminate the voltage drop on the PTC resistance, and improve the DC bus voltage output by the rectifier module 13, so as to ensure the stable work of the switching power supply module 14.

[0086] In this way, the false action caused by transient voltage fluctuation or temporary power failure can be effectively avoided, the relay K1 is prevented from being frequently turned on and off, and the anti-interference ability and operation reliability of the system are improved. At the same time, by dynamically adjusting the voltage threshold for restoring the closed state based on the new bus voltage maximum value, the system can adapt to different grid environments and realize precise power management, so as to maximize the energy saving effect while ensuring stability.

[0087] In an embodiment of the present application, when the new bus voltage maximum value is less than the difference, and the second duration is greater than the second preset time, the controller 71 is configured to: obtain a third duration during which the relay K1 is closed; and control the relay K1 to be open after the third duration reaches a third preset time.

[0088] In an embodiment, when the controller 71 determines that the new bus voltage maximum value is less than the difference between the new bus voltage maximum value and the preset back-off voltage threshold, that is, the actual DC bus voltage has fallen back to the voltage safety range, and the open time of the relay K1 has exceeded the second preset time, in order to restore the system power supply reliability, the controller 71 controls the relay K1 to be closed, and switches to the low resistance conduction path again, so as to improve the DC bus voltage and ensure the stable work of the switching power supply module 14. On this basis, in order to prevent the system from being in a high power consumption state for a long time and still maintain the energy saving ability after the grid voltage is temporarily raised, the controller 71 starts to count the third duration during which the relay K1 is closed after the relay K1 is closed.

[0089] When the third duration reaches the third preset time, the controller 71 determines that the system has been sufficiently stabilized under the power supply of the path where the relay K1 is located, and the grid voltage has been maintained at a high level for a period of time, and the conditions for entering the energy-saving mode again are met. At this time, the controller 71 controls the relay K1 to be disconnected again, so that the power supply path is switched back to the PTC resistance path, and under the premise of ensuring that the system can still operate normally, the power consumption of the relay K1 driving coil is eliminated, for example, about 0.96 W, and the system reenters the low-power standby state.

[0090] In this way, the automatic reset function after the relay K1 is closed can be realized, the additional energy consumption caused by the long-term closure of the relay K1 is avoided, the system can intelligently recover and save energy again after coping with voltage fluctuations, thereby guaranteeing the operation reliability under low-voltage conditions, and the energy efficiency optimization of long-term standby is also taken into account, and the self-adaptive ability and comprehensive performance of the air conditioner 10 in a complex power grid environment are improved.

[0091] In an embodiment of the present application, when obtaining the new bus voltage maximum value during the disconnection of the relay K1, the controller 71 is configured to: obtain a first voltage feedback signal during the disconnection of the relay K1; determine a first actual direct current bus voltage according to the first voltage feedback signal; and when the first actual direct current bus voltage is greater than the bus voltage maximum value, update and store the first actual bus voltage as the new bus voltage maximum value.

[0092] In an embodiment, after the relay K1 is disconnected, the controller 71 obtains the first voltage feedback signal provided by the detection module 15 in real time, and the controller 71 calculates the corresponding first actual direct current bus voltage value according to the first voltage feedback signal and in combination with a preset voltage division ratio.

[0093] Subsequently, the controller 71 compares the first actual direct current bus voltage detected in real time with the currently stored bus voltage maximum value (i.e., the highest voltage recorded during the last closure or previous disconnection of the relay K1). If it is detected that the first actual direct current bus voltage is higher than the stored value, it indicates that the current grid voltage has risen, and the system is in a more optimal power supply state. At this time, the controller 71 immediately updates the higher voltage value as the new bus voltage maximum value and stores it. In this way, the system realizes the adaptive learning ability to the power supply environment, enhances the intelligence and reliability of the control logic, and avoids misjudgment caused by a fixed threshold.

[0094] In an embodiment of the present application, when controlling the on-off state of the relay K1 based on the comparison result of the actual DC bus voltage with the preset minimum working voltage threshold and the hysteresis voltage threshold, the controller 71 is configured to: obtain the actual DC bus voltage of the relay K1 during the opening period or the closing period in real time, and update and store the current actual DC bus voltage as the latest maximum bus voltage when it is detected that the current actual DC bus voltage is greater than the stored maximum bus voltage.

[0095] In an embodiment, when controlling the on-off state of the relay K1, the controller 71 continuously obtains the actual DC bus voltage of the relay K1 during the closing or opening period in real time. By means of the voltage feedback signal of the detection module 15, the controller 71 constantly compares the current actual DC bus voltage with the stored maximum bus voltage. Once it is detected that the current actual DC bus voltage is higher than the stored maximum bus voltage, it is updated as the latest maximum bus voltage and stored. Thus, it is ensured that the system is always based on the highest voltage that occurs recently, dynamically adapts to the power grid changes, and avoids misjudgment caused by voltage fluctuations. Through full-period voltage monitoring and automatic updating, the controller 71 realizes intelligent tracking of the power supply state, improves the accuracy of the on-off control of the relay K1 and the stability of the system operation, and enhances the adaptability of the standby energy-saving strategy.

[0096] According to the air conditioner 10 of the embodiment of the present application, when the air conditioner 10 is powered on and in the standby state, the controller 71 receives the voltage feedback signal detected by the detection module 15, determines the actual DC bus voltage corresponding thereto according to the voltage feedback signal, compares the actual DC bus voltage with the preset minimum working voltage threshold and the hysteresis voltage threshold, and controls the on-off state of the relay K1 according to the comparison result, so as to switch the conduction path of the buffer starting module 12 according to the closing state or the conduction state of the relay K1, and further adjust the power supply state of the input power supply 11 to the rectifier module 13. In this way, not only can the controller 71 itself be reliably powered on and continuously operated under abnormal working conditions such as power grid voltage fluctuation or low input voltage, but also the power supply mode can be automatically switched according to the voltage condition in the standby state, which not only significantly reduces the standby power consumption, but also effectively widens the operable voltage range of the controller 71. Moreover, without the need for additional complex elements, the energy saving, reliability and wide voltage adaptability can be taken into account, thereby reducing the overall cost of the system.

[0097] The following refers to Figures 5-8 a control method of an air conditioner of an embodiment of the present application.

[0098] As Figure 5 shown, the control method of the air conditioner of the embodiment of the present application at least includes step S1.

[0099] Step S1: When the air conditioner is powered on and in standby mode, a voltage feedback signal is received, the corresponding actual DC bus voltage is determined according to the voltage feedback signal, and the on / off state of the relay is controlled based on the comparison result of the actual DC bus voltage with the preset minimum operating voltage threshold and the hysteresis voltage threshold, so as to switch the conduction path of the buffer start module, thereby adjusting the power supply state of the input power supply to the rectifier module. The preset minimum operating voltage threshold is the minimum input voltage required for the switching power supply module to work.

[0100] In one embodiment of the present invention, before receiving the voltage feedback signal, the method includes: controlling the relay to disconnect, so that the AC input voltage provided by the input power supply supplies power to the rectifier module through the path of the PTC resistor to establish the DC bus voltage, thereby powering on the switching power supply module, the detection module and the controller and putting them into normal operation.

[0101] In one embodiment of the present invention, before controlling the on / off state of the relay based on the comparison result of the actual DC bus voltage with the preset minimum operating voltage threshold and the hysteresis voltage threshold, the method includes: controlling the relay to remain in a closed state for a first preset time.

[0102] In one embodiment of the present invention, such as Figure 6 As shown, when controlling the on / off state of the relay based on the comparison results of the actual DC bus voltage with the preset minimum operating voltage threshold and the hysteresis voltage threshold, the following steps are included: obtaining the first duration of the relay closure; when the first duration is greater than the first preset time, and the actual DC bus voltage is less than or equal to the sum of the preset minimum operating voltage threshold and the hysteresis voltage threshold, determining whether the actual DC bus voltage is less than the preset minimum operating voltage threshold; if so, controlling the relay to remain closed.

[0103] In one embodiment of the present invention, such as Figure 6 As shown, when controlling the on / off state of the relay based on the comparison results of the actual DC bus voltage with the preset minimum operating voltage threshold and the hysteresis voltage threshold, the following steps are taken: when the first duration is greater than the first preset time and the actual DC bus voltage is greater than the sum of the preset minimum operating voltage threshold and the hysteresis voltage threshold, the relay is controlled to open, and the currently detected actual DC bus voltage is stored as the maximum value of the bus voltage.

[0104] In one embodiment of the present invention, such as Figure 7 As shown, after controlling the relay to disconnect and storing the currently detected actual DC bus voltage as the maximum bus voltage, the process includes: obtaining the second duration of the relay disconnection and the new maximum bus voltage during the relay disconnection period; and controlling the on / off state of the relay based on the second duration and the new maximum bus voltage.

[0105] In one embodiment of the present application, as shown in Figure 7 controlling the on-off state of the relay according to the second duration and the new bus voltage maximum value comprises: determining a difference between the new bus voltage maximum value and the back-off voltage threshold; when the new bus voltage maximum value is less than the difference and the second duration is greater than the second preset time, controlling the relay to close.

[0106] In one embodiment of the present application, as shown in Figure 7 controlling the relay to close when the new bus voltage maximum value is less than the difference and the second duration is greater than the second preset time comprises: obtaining a third duration for which the relay is closed; after the third duration reaches a third preset time, controlling the relay to open.

[0107] In one embodiment of the present application, as shown in Figure 8 obtaining the new bus voltage maximum value during the period when the relay is open comprises: obtaining a first voltage feedback signal during the period when the relay is open; determining a first actual DC bus voltage according to the first voltage feedback signal; when the first actual DC bus voltage is greater than the bus voltage maximum value, updating the first actual bus voltage to the new bus voltage maximum value and storing it.

[0108] In one embodiment of the present application, when controlling the on-off state of the relay based on the comparison result of the actual DC bus voltage with the preset minimum working voltage threshold and the back-off voltage threshold, it comprises: obtaining the actual DC bus voltage of the relay during the period when the relay is open or closed in real time, and when it is detected that the current actual DC bus voltage is greater than the stored bus voltage maximum value, updating the current actual DC bus voltage to the latest bus voltage maximum value and storing it.

[0109] The control method of the air conditioner according to the embodiment of the present application, when the air conditioner is powered on and in standby state, receives the detected voltage feedback signal, determines the actual DC bus voltage corresponding to the voltage feedback signal, and compares the actual DC bus voltage with the preset minimum working voltage threshold and the back-off voltage threshold, controls the on-off state of the relay according to the comparison result, switches the conduction path of the buffer starting module according to the closed state or the conduction state of the relay, and further adjusts the power supply state of the input power supply to the rectifier module. In this way, not only can the controller itself be reliably powered on and continuously run under abnormal working conditions such as grid voltage fluctuation or low input voltage, but also can automatically switch the power supply mode according to the voltage condition in standby state, significantly reduce the standby power consumption, and effectively widen the operating voltage range of the controller. Moreover, without additional complex elements, energy saving, reliability and wide voltage adaptability can be considered, thereby reducing the overall system cost.

[0110] In the description of the specification, reference to "one embodiment", "some embodiments", "an exemplary embodiment", "an example", "a specific example", or "some examples" means that a particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of the phrases "in one embodiment", "in some embodiments", "in an exemplary embodiment", "an example", "a specific example", or "some examples" in various places in the specification are not necessarily referring to the same embodiment or example.

[0111] While embodiments of the application have been shown and described, it is to be understood that the application is not limited to these embodiments. Rather, it is the intention that modifications, changes, substitutions, and variations be made to the embodiments in keeping with the principles and spirit of the application. The scope of the application is to be limited only by the claims and their equivalents.

Claims

1. An air conditioner characterized by comprising: The application relates to an air conditioner buffer starting module. An input power supply is arranged to provide an alternating input voltage. A buffer starting module is arranged to include a PTC resistor and a relay connected in parallel, one end of the PTC resistor and one end of the relay being connected to the input power supply. A rectifier module is arranged to have one end connected to the other end of the PTC resistor and the other end of the relay, and is used to rectify the alternating input voltage into a direct current bus voltage. A switching power supply module is arranged to have one end connected to the other end of the rectifier module, and is used to convert the direct current bus voltage into low-voltage direct current to supply power to a controller and a detection module. The detection module is arranged to have one end connected to the other end of the rectifier module, and is used to detect the direct current bus voltage and generate a corresponding voltage feedback signal. The controller is arranged to have one end connected to the relay, the switching power supply module and the detection module, and is used to receive the voltage feedback signal when the air conditioner is powered on and in a standby state, determine an actual direct current bus voltage according to the voltage feedback signal, and control the on-off state of the relay based on the comparison result of the actual direct current bus voltage, a preset minimum working voltage threshold value and a hysteresis voltage threshold value, so as to switch the conduction path of the buffer starting module and adjust the power supply state of the input power supply to the rectifier module, wherein the preset minimum working voltage threshold value is the minimum input voltage required for the switching power supply module to work.

2. The air conditioner of claim 1, wherein Before receiving the voltage feedback signal, the controller is configured to: control the relay to be disconnected, so that the alternating input voltage provided by the input power supply passes through the path where the PTC resistor is arranged to supply power to the rectifier module, to establish the direct current bus voltage, so that the switching power supply module, the detection module and the controller are powered on and enter a normal working state.

3. The air conditioner of claim 1, wherein Before controlling the on-off state of the relay based on the comparison result of the actual direct current bus voltage, the preset minimum working voltage threshold value and the hysteresis voltage threshold value, the controller is configured to: control the relay to remain in a closed state for a first preset time.

4. The air conditioner of claim 3, wherein When controlling the on-off state of the relay based on the comparison result of the actual direct current bus voltage, the preset minimum working voltage threshold value and the hysteresis voltage threshold value, the controller is configured to: acquire the first duration for which the relay is closed; when the first duration is greater than the first preset time and the actual direct current bus voltage is less than or equal to the sum of the preset minimum working voltage threshold value and the hysteresis voltage threshold value, determine whether the actual direct current bus voltage is less than the preset minimum working voltage threshold value; if yes, control the relay to remain in the closed state.

5. The air conditioner of claim 4, wherein When controlling the on-off state of the relay based on the comparison result of the actual direct current bus voltage, the preset minimum working voltage threshold value and the hysteresis voltage threshold value, the controller is further configured to: When the first duration is greater than the first preset time, and the actual DC bus voltage is greater than the sum of the preset minimum operating voltage threshold and the back-off voltage threshold, the controller controls the relay to be opened, and stores the actual DC bus voltage currently detected as a bus voltage maximum value.

6. The air conditioner of claim 5, wherein After the controller controls the relay to be opened and stores the actual DC bus voltage currently detected as a bus voltage maximum value, the controller is configured to: obtain a second duration for which the relay is opened, and a new bus voltage maximum value during the period for which the relay is opened; control the on-off state of the relay according to the second duration and the new bus voltage maximum value.

7. The air conditioner of claim 6, wherein When the controller controls the on-off state of the relay according to the second duration and the new bus voltage maximum value, the controller is configured to: determine a difference between the new bus voltage maximum value and the back-off voltage threshold; when the new bus voltage maximum value is less than the difference, and the second duration is greater than a second preset time, control the relay to be closed.

8. The air conditioner of claim 7, wherein When the controller controls the relay to be closed when the new bus voltage maximum value is less than the difference, and the second duration is greater than a second preset time, the controller is configured to: obtain a third duration for which the relay is closed; after the third duration reaches a third preset time, control the relay to be opened.

9. The air conditioner of claim 7, wherein When the controller obtains the new bus voltage maximum value during the period for which the relay is opened, the controller is configured to: obtain a first voltage feedback signal during the period for which the relay is opened; determine a first actual DC bus voltage according to the first voltage feedback signal; when the first actual DC bus voltage is greater than the bus voltage maximum value, update the first actual DC bus voltage as a new bus voltage maximum value and store the new bus voltage maximum value.

10. The air conditioner of claim 1, wherein When the controller controls the on-off state of the relay based on the comparison result of the actual DC bus voltage, the preset minimum operating voltage threshold, and the back-off voltage threshold, the controller is configured to: obtain the actual DC bus voltage of the relay in real time during the period for which the relay is opened or closed, and when it is detected that the current actual DC bus voltage is greater than the stored bus voltage maximum value, update the current actual DC bus voltage as the latest bus voltage maximum value and store the latest bus voltage maximum value.

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