New approach of average modelling and control for AC/DC power supplies which operates with variable duty cycle

In power factor correction (PFC) applications, a conventional boost-type AC/DC converter uses a double control loop to shape the input current as well as to regulate output voltage. In order to reduce the cost, most of single-stage approach removes one of the control loops. Therefore a single control loop has to tightly regulate the output voltage and shape input current under very variable conditions (variable line voltage, instantaneous and rms values, variable load power). In order to reduce the effect of the loop features on the input current and on the output voltage, it is very important to make a tight design of the loop compensator, so, accurate models are required. This paper presents a general averaging method for single-stage converters and also a novel design procedure of the loop compensator is proposed. Simulation and experimental results are provided to verify both the averaging technique and the control method.