A D-Q Frame Controller for a Full-Bridge Single Phase Inverter Used in Small Distributed Power Generation Systems

This paper presents a Direct-Quadrature (DQ) rotating frame control method for single phase full-bridge inverters used in small hybrid power systems. A secondary orthogonal imaginary circuit is created to provide the second phase required for the transformation; thus a DQ model of the inverter is obtained and its controller designed emulating the controls of three-phase power converters. The proposed controller attains infinite loop gain in the rotating coordinate, thus providing zero steady-state error at the fundamental frequency of the converter. The proposed controller is designed and validated through simulations using a DQ-frame average model in Matlab and a detailed switching model in Saber, as well as experimental results obtained with a 2.5 kW single phase full-bridge inverter prototype using a DSP/FPGA based digital control system where the proposed DQ-frame controller is fully implemented.