Multilevel PWM for single-phase power factor pre-regulator

A new single-phase bridge rectifier with three-level pulse width modulation (PWM) is proposed. A power factor corrector to improve the power quality is presented. The hysteresis current control (HCC) technique for a bridge rectifier with two AC power switches is adopted. The control schemes stored in programmable array logic (PAL) are implemented such that the line current is driven to follow the reference current. The reference current is derived from the a DC link voltage regulator and an output power estimator. The major advantage of using three-level PWM is that the blocking voltage of each AC power device is clamping to half of the DC link voltage. The high power factor and low harmonic currents at the input of the rectifier are verified by software simulations.