An on-line operated unity power factor PWM rectifier for AC driveapplications

摘要

In order to minimize their impact on the AC supply, AC drivesoften require an input rectifier stage with low input current harmonicsand high input power factor. High efficiency is also desirable.Drawbacks of the conventional off-line operated PWM rectifiers includeslow transient response, load dependent input power factor and the needfor damping resistors to avoid harmonic amplification and currentoscillations, particularly under transient conditions. In this paper, anon-line operated PWM rectifier with inherent damping and patternsynchronization with the AC mains is proposed. Since the modulationscheme uses the voltages across the input filter capacitors astemplates, faster transient response is achieved under normal andstarting conditions and the need of the damping resistors is eliminated.Moreover, an additional phase-shifting circuit is used in the controlscheme to achieve unity power factor, independently of the DC linkcurrent variations. The paper includes analysis and design guidelinesfor the rectifier control circuit. Experimental results on a 1 kVAlaboratory prototype confirm the feasibility of the proposed controlstructure