A new single-phase single-switch PWM three-level high power factor rectifier with separate regulation of output capacitors voltage

摘要

In this paper, a new control scheme is proposed for the new single-phase single-switch three-level rectifier to supply two different load with different voltages and draw sinusoidal line current with low THD. The adopted rectifier consists of a diode bridge, a power switch and two blocking diodes. Low cost, simple structure and convenient control and three level voltage are the main advantages of this rectifier. But the main drawback of this rectifier is existence of dc and second order harmonic in line current. A two loop controller is developed to control each capacitors, separately. A voltage controller based on PI controller regulates each capacitors voltage in the outer loop, while the current controller based on hysteresis comparator in inner loop control the input current. An input current sign detector is used to select the appropriate switching state from a look-up table. Analytical and computer simulation results are presented to show the efficient operation and advantages of the presented rectifier.