Abstract: The present application relates to a power failure detection circuit, the circuit comprises: a rectifying circuit for full-wave rectifying an alternating current voltage so as to obtain a first voltage; a switching circuit for converting the first voltage into a periodic voltage pulse; and a judgment circuit for providing an output signal to a fan control circuit for closing a fan when the periodic voltage pulse is not received within a preset time period, and providing the output signal to a micro-control unit for closing an electronic expansion valve. The present application also relates to a control circuit for a variable refrigerant flow VRF system.

Abstract: The present application relates to a battery box, the battery box comprising: a charging and energy storage unit for charging and storing electrical energy using an input voltage supplied to the battery box; a power failure detection unit for detecting a power failure of the input voltage; and a power output switching unit for switching an output based on a detection result of the power failure detection unit, wherein the power output switching unit is configured to output a voltage from the charging and energy storage unit when the power failure detection unit detects a power failure, and is configured not to output the voltage when the power failure detection unit does not detect the power failure. The present application also relates to an air conditioning system and a control method for the air conditioning system.

Abstract: A heat pump system comprises: an indoor unit comprising an air conditioning unit and a refrigeration cabinet unit, and an outdoor unit comprising a compressor unit, an outdoor heat exchange unit, and a switching device for selectively connecting the exhaust end of the compressor unit to one of the air conditioning unit and the outdoor heat exchange unit, and connecting the suction end of the compressor unit to the other of the air conditioning unit and the outdoor heat exchange unit; wherein, the outdoor throttling device side of the outdoor heat exchange unit is respectively connected to the first port of the air conditioning unit and the first port of the refrigeration cabinet unit, and the second port of the refrigeration cabinet unit is connected to the suction end of the compressor unit.