A fan is a type of air conditioning appliance that uses a motor to rotate fan blades, thereby driving airflow and facilitating the exchange of indoor and outdoor air. The function of an internal fan is to remove stale indoor air, regulate temperature and humidity, and achieve air circulation. The main customer requirements for fans are threefold: Energy efficiency, adaptive self-regulation based on load changes, and flexibility to meet various customer application needs.
Traditionally, AC motors have been used as the driving device for fan impellers, but EC technology offers many advantages that are becoming increasingly difficult to ignore. While kilowatt-level three-phase AC asynchronous motors have satisfactory efficiency at full load, the efficiency of single-phase or sub-kilowatt three-phase motors is often insufficient. AC motors also require the use of frequency converters to control speed, which leads to power losses and requires additional filters to protect sensitive motor bearings. Asynchronous motors driven by frequency converters at partial load often generate noise, causing the motor to hum.