Inductor voltage controlled variable power factor buck-type AC-DC converter

Abstract

A novel inductor voltage control method capable of achieving any input power factor including unity is being proposed for both the single and three phase buck type ac-dc PWM converters. In this method, the input inductor voltage is kept within a hysteresis band about a sinusoidal template, thus ensuring sinusoidal input current. This control is much less sensitive to parameter and control signal changes than the existing delta modulation technique. Detailed analysis has been performed for a single phase converter. A new switching logic scheme is then proposed which enables the inductor voltage control (and delta modulation control) to be extended to a three phase converter also. For both single phase and three phase converters, simulation and experimental results have been provided. The proposed inductor voltage control method has potential in applications such as dc motor drives and ac-dc rectifier with current limiting.