The design and development of a high power factor current source controller for small appliance brushless DC motors

The harmonic content in electric utility supply current has increased recently due to the proliferation of devices using peak rectifiers. This paper presents a variable speed high power factor DC motor controller with application in small appliances. The circuit uses a single high-voltage high-frequency switching transistor in a buck power converter topology. Theoretical analysis shows a large pulse width range giving a broad RFI/EMI spectrum. Experimental results verify the design with a 50 watt prototype controller having a power factor of 0.99