A New SVPWM Dead-Time Compensation Strategy for Low Speed Direct-Drive Motor

Abstract

Traditional space vector pulse-width modulation (SVPWM) algorithm included complex calculations like triangle functions and square root, which increased execution time of the program. A novel SVPWM algorithm calculating modulation functions of three phases through stationary αβ components of reference voltage vectors was proposed here to solve the problem, which was composed of only simple four arithmeticoperations. The method simplified traditional SVPWM and improved real-time performance of digital control system. However, dead-time effect still existed in novel SVPWM algorithm. And it will lead to distortions of low speed direct-drive PMSM phase currents, brought increase of speed fluctuation, resulted in unstable operating of servo system. This paper analyzed details of error voltage vectors led by dead-time effect, researched relationship between error voltage vectors and polarities of three phase currents, and put forward a novel dead-time compensation strategy that decreased influence of zero current clamping. Simulation results showed that this strategy can effectively compensate effects of dead-time error voltage vector and improve wave forms of phase currents, which increased operating performance of low speed direct-drive PMSM.