Predictive Direct Power Control Technique for Voltage Source Converter With High Efficiency

Abstract

A predictive direct power control (PDPC) technique to decrease switching loss by injecting offset voltage is proposed for three-phase voltage source converters. The active and reactive power elements of the converter are directly controlled by using three-phase future converter input voltages, which are modified for lowering switching losses by injecting a future offset voltage. Switching operations, generated by the developed PDPC algorithm with modified converter voltage, stop switching operation in one of the converter phases exposed to the highest input current. The non-switching period and the non-switching phase in the proposed technique is automatically adjusted by the reactive power reference, which leads to high efficiency, irrespective of varying input power factor angle condition. The proposed algorithm chooses one optimal voltage vector enabling future active and reactive power to approach closest to the future power references and prohibiting switching of one converter phase conducting the highest current at each step. Therefore, the developed technique can directly control power components and increase converter efficiency, which is proven by simulation and experimental verification.