Fast controller design for practical power-factor correction systems

A fast controller is presented for single-phase boost derived power-factor correction circuits. An adaptive estimator is used to remove the twice line frequency ripple component from the measured output voltage. As the output voltage feedback loop no longer contains a ripple component the sub line-frequency low pass filter found in traditional designs is dispensed with. Time constants in the voltage feedback loop are improved by an order of magnitude giving a similar reduction in output voltage overshoots. The controller copes with considerable uncertainty in input voltage magnitude, line frequency and output capacitance. All sections of the control system are shown to be asymptotically stable and suitable bounds are placed on feedback loop cross-over frequencies. Simulation results are presented to verify the excellent dynamics and robust behaviour of the design. It is concluded that the superior performance over traditional designs warrants the small increase in controller complexity