PWM Current Controllers for a Family of 3-Switch Utility Rectifier Topologies

Unipolar pwm current control techniques are presented for a family of 3-switch utility UFPF rectifier topologies operated with a low current THD. This paper presents preliminary results of a research program intended to compare the performance of 2-current and 3-current controllers, using either hysteresis control or a sawtooth reference signal to achieve synchronized switching. The quality of the current waveshape generated are to be examined under balanced and unbalanced ac supply conditions, together with several techniques required to improve the current waveshaping. This paper presents the switching logic tables required to implement the 2-current controller for both the delta and star connected switch topologies. A basic switching topology cell is used as a reference for defining the switching functions. Spice simulation results are used to demonstrate the preliminary results for the proposed controllers.