Development of an SVPWM-based predictive current controller for three-phase grid-connected VSI

As a voltage type modulator, space vector PWM (SVPWM) has been widely applied in the current control of three-phase voltage source inverters (VSI). However, SVPWM has certain drawbacks compared with current type modulators. For a grid-connected VSI, the performance of current controller based on SVPWM is compromised by grid harmonics and system nonlinearity such as the control delay due to computation and sampling. In this paper, a novel SVPWM-based predictive current controller is proposed to effectively compensate for grid harmonics and completely eliminate the effect of control delay using software predictors and filters based on a dual-timer sampling system. The controller operates in the synchronous d-q reference frame and mimics the dead-beat control to control the output current to achieve its reference in each PWM period. Both simulation and experimental test results show that the proposed predictive current controller has an excellent steady state response as well as extremely fast dynamic response.