The fan is one of the important core components in the photovoltaic power generation system. The centralized photovoltaic inverter has a large power and usually adopts forced air cooling. Most of the inverters are placed outdoors, and the operating environment is relatively harsh. Therefore, the protection level of the whole equipment is required to be high. Most of the fans are installed inside the equipment. Therefore, in order to ensure the compact structure of the equipment, the size of the fan should be selected as small as possible.