A Novel Switching Table Direct Power Control for PWM Rectifier Based on Virtual Flux

Abstract

A novel switching table direct power control strategy based on virtual flux for the three-phase voltage source pulse width modulation (PWM) rectifier is proposed to improve the steady-state performance. First, this paper employs a fast integration algorithm to avoid saturation and dc-drift problems in virtual flux calculation. Based on the control amplitude of switching vector to active power and reactive power, the 12 sectors of the traditional virtual flux direct power control (VF-DPC) are subdivided into 24 sectors. Then, the active power difference interval judge is designed, according to its output and the output of power hysteresis comparator, the optimal switching vector of current sector is selected to construct a novel switching table to achieve accurate control of the active power. Simulation comparison indicates that the novel switching table not only overcomes the shortcomings of the traditional switching table in terms of poor control of reactive power, but also improves the current THD on grid side and reduces the output DC voltage, active and reactive power ripple.