Method for controlling expansion valve of frequency conversion heat pump clothes dryer

A method for controlling an expansion valve of a frequency conversion heat pump clothes dryer, a frequency conversion compressor of the clothes dryer comprising a frequency ascending stage, a frequency retaining stage, and a frequency descending stage, the method comprising:

• adjusting an open degree of the expansion valve through one of parameters selected from a group comprising an operation time at a certain frequency, power, current and an operation frequency of the frequency conversion compressor;
• wherein the clothes dryer includes a first drying mode and a second drying mode, an operation time of the frequency conversion compressor in a high-frequency band in the first drying mode is longer than the operation time of the frequency conversion compressor in the high-frequency band in the second drying mode, and the open degree of the expansion valve in the first drying mode when it enters in the frequency descending stage is larger than the open degree of the expansion valve in the second drying mode when it enters in the frequency descending stage.