A digital controller for a unity power factor converter

Abstract

Digital control is rare in the area of power converters due mainly to cost considerations. As operating requirements of power supplies become more stringent, however, their control poses difficult problems better dealt with using digital rather than analog control. With the falling prices of microcontrollers and the increase in their processing power, microprocessor-based controllers for power converters should soon become practical. In this thesis, a digital controller for a Unity Power Factor AC-DC converter is designed, based on a linear large-signal model of the power supply. A hardware implementation of the design is presented and analyzed, along with simulations of the closed-loop system. Issues in digital control of power systems, such as quantization effects and fixed-point representation of system parameters, are examined in the context of this system. An adaptive controller is then designed and implemented using the same system. The experimental results are then compared with the simulations and used to evaluate the implementation.