A Simple Digital Controller for Constant Instantaneous Input Power type Three-Phase Boost Rectifier under Unbalanced System

Abstract

Power Factor Correction (PFC) rectifiers are essential for load side harmonic and reactive power correction. In recent years, research and applications of PFC rectifiers have attracted more attention due to the increased energy awareness in the global. In this paper, a simple digital controlled three-phase six-switch H-bridge boost rectifier is proposed. The control objective is to operate the rectifier in the high power factor mode under normal operating condition, but to give an overriding priority to the constant instantaneous input power in the case of unbalanced input voltages. This results in that the low order harmonics of output DC voltage are eliminated whenever in balanced or unbalanced input voltages, and with this control method, the output capacitor can be significantly minimized. The controller has three loops: the inner loop implements resistor emulator type input average current strategy; the input voltage forward loop performs constant input power regulator; the output voltage loop performs magnitude scaling operations on input current control. The system is implemented in full digital, and one Texas Instrument's DSP TMS320F240 is used as the digital controller.