System and method for realizing defrosting control by photoelectric conversion

The invention discloses a system and a method for realizing defrosting control of refrigerating devices such as an air source heat pump unit, a heat pump room air conditioner, and the like. The invention adopts the technical scheme that photoelectric sensors, each of which comprises an emitter and a receiver, are arranged on both sides of a refrigerating device so as to be used for defrosting; a current source is connected with the emitter and used for inputting current to the emitter; the receiver is used for receiving an optical signal output by the emitter and converting the optical signal into a voltage signal; a voltage signal collector is connected with the receiver and used for receiving the voltage signal converted by the receiver; and a defrosting controller starts or stops a defrosting operation according to the voltage signal obtained by the voltage signal collector. The method can effectively control the defrosting operations of the refrigerating devices such as the air source heat pump unit, the