DQ current control of a bidirectional, isolated, single-stage AC-DC converter for vehicle-to-grid applications

Electric vehicles can provide a viable network of distributed energy storage and provide ancillary services to the grid, (Vehicle-to-Grid, V2G), but Electric Vehicle chargers need to be bidirectional in order to provide power back to the grid. In this paper, dq current control is proposed using a novel bidirectional, isolated, single stage AC-DC converter. Unity open loop power factor has been achieved in previous work using the novel topology but relies on a non-distorted voltage waveform to achieve unity power factor and lacks control of reactive power. The single phase input filter equations are transformed into the rotating dq reference frame by generating an imaginary beta axis. The filter dynamics are analyzed and controllers are designed for dq input currents. A phase shift component is added to the modulation scheme allowing control of the phase and magnitude of the converters input current. The topology and control scheme is simulated in PLECS. Simulation results are presented for various operating points and validate the theoretical analysis. The proposed control strategy implements real and reactive power control which is essential for V2G applications and the topology has the advantages of high switching frequency, isolation, voltage matching, high power density, and reduced size compared to the conventional cascaded isolated AC-DC topologies.