Gain controlled high efficiency power factor correction circuit

Abstract

The purpose of this study is to improve the efficiency of a boost-type power factor correction ( PFC) circuit with a digital controller. One of the biggest losses in PFC circuits is the switching loss. Switching loss can be reduced by low boost ratio operation, but these results in a greater voltage drop at transient response. The voltage drop can be suppressed by using a high gain setting for the voltage control loop, but this lowers the power factor, which creates a harmonic distortion of the AC power line. To improve this trade-off, we developed a gain control method that adjusts the gain to high only at the moment of transient response. This method improves both the efficiency and the power factor ofPFC circuits. We implemented the proposed method using a digital controller and demonstrated a power factor improvement of 0.08 points and an efficiency improvement of 0.4 points for a 2.5 kW PFC circuit.

Rapid control prototyping for server power supply with high-resolution PWM

“…Those studies show that digital control with an embedded microprocessor unit (MPU) is an effective way of improving efficiency. The precise Pulse Width Modulation (PWM) timing control and new control logic are implemented in the MPU, which enables optimization of the dead time of choppers [6], [7], [8], switching frequency [9], voltage and gain [10], which reduce the loss of power supply. Also, a new digital filter for feedback controller can implement a high order compensator, which is not possible with the conventional analog circuit [11], [12].…”