Close loop control to bidirectional isolated single stage DAB with resonant circuit DC/AC converter to connection of batteries to the single phase grid

摘要

A novel modulation strategy and close loop control is proposed for an isolated, highly efficient bidirectional single stage DC/AC converter dedicated to connection of batteries to single phase grid. Modulation, design and close loop control are discussed to 500W converter prototype. The converter is composed of two active bridges, a series resonant circuit, an HF transformer and a synchronous rectifier. The novel modulation strategy keep phase shift modulation which allows a bidirectional power flow between the battery and the grid but, an additional duty ratio control in both actives bridges is proposed. With this modulation the converter can works with any AC grid amplitude and frequency without any change in the converter structure. Controller type PR+PD and DQ are analyzed. Bidirectional power flow has been validated with power factor closest to unity. High efficiency of 96% has been obtained owing to Zero Voltage Switching (ZVS) in all MOSFETs. Finally, the modulation and the controller have been validated experimentally for different cases.