A simple design method for nonlinear control of powerfactor correction boost converter

Abstract

Typical switched-mode power supplies employ diode rectifiers for the AC to DC conversion. They draw input current in short pulses rather than in smooth sine waves and this puts stress on the wiring, circuit breakers and even distribution equipment provided by utilities. This type of utility interface generates harmonics and both of the input power factor (PF) and total harmonic distortion (THD) are poor. To minimize the stresses and maximize the power handling capabilities, active power factor correction (PFC) circuitry can be added to improve the shape of the input current. This work is aimed at providing a simple design method for power factor correction (PFC) boost converter for a non-linear power system to improve the disturbance rejection and speed of response of the conventional nonlinear cascade controller. Model based cascade controller design is presented for the control of PFC boost converters. Also, a dead band relay is introduced in the voltage loop to improve the disturbance rejection and speed of response of the PFC boost converter. Circuit implementation of the proposed control scheme is presented and simulation results are included to demonstrate the effectiveness of the proposed design scheme. The outcome indicated that resultant power factor is over 0.99, the total harmonic distortion of supply current is less than 2.9% and the efficiency of the converter is 93% at full load. It is recommended that a MOSFET based switching device could be used to improve the system.