A novel multilevel PWM control scheme of the AC/DC/AC converter for AC drives

An AC/DC/AC power converter with three-level pulse width modulation is proposed in this paper. A single-phase power factor correction circuit to improve the power quality in the rectifier and a three-level PWM inverter to reduce the harmonic contents of the inverter output voltages are presented. In the rectifier side, the hysteresis current control (HCC) technique for a bridge diode with two power switches is adopted. A control scheme is presented that the line current is driven to follow the reference sinusoidal current which is derived from the DC link voltage regulator, DC capacitor voltage balance compensator and the output power estimator. A three-level PWM technique for a three-phase voltage source inverter is used to reduce the voltage harmonics. The major advantage for using such strategy is that the blocking voltage of each power device is clamping to half of the DC link voltage. The high power factor at the input of the rectifier and the low total harmonic distortion at the output of the inverter are verified by software simulations.