Improved Dead-Beat Predictive DPC Strategy of Grid-Connected DC–AC Converters With Switching Loss Minimization and Delay Compensations

Abstract

This paper presents an improved dead-beat predictive direct power control (DPC) strategy for grid-connected dc-ac converters. In order to minimize switching losses and to alleviate power oscillations, a new voltage vectors' sequence is proposed for the predictive DPC strategy based on the angular location of the required converter voltage vector rather than the grid voltage vector. Thus, low-order harmonics in ac currents and periodic oscillations in the reactive power are removed with the feature of minimum switching losses kept. Further, in order to reduce steady-state errors of active and reactive powers, compensation methods are proposed in practical systems for both power errors and angular shifts caused by sampling delays. Experimental results on a 1.5 kW grid-connected dc-ac converter are provided to validate the feasibility of the proposed voltage vectors' sequence and compensation methods for the predictive DPC strategy.