High-Efficiency Bidirectional Three-Phase LCC Resonant Converter with a Wide Load Range

This paper details the design and implementation of an efficient 4-kW bidirectional converter with a wide load range, based on a three-phase LCC resonant converter operated in a continuous conduction model, which has a number of advantages pertaining to a bidirectional power supply. The voltage boost-up function yields a high voltage gain without increasing the transformer turn ratio. The high switching frequency, which is achievable by using the soft-switching condition and multiphase operation, decreases the output ripple and helps minimize the size of the output filter, as the requirement for a filter changes after the power flow. Moreover, this reduction in the size of the filters yields economic advantages. In addition, because of the synchronous rectifier operation employed during switching, the conduction loss in the rectifier diode of the proposed converter is low. The direction of the output power can be changed easily, using phase control. The implemented power converter is connected to a 320-V rated generator on one side and 28-V lead-acid batteries on the other side. The functionality of the proposed converter is verified in experiments. We confirmed the high performance of the developed converter in terms of efficiency (92.2%), operable load range (0-12.5 A in step-up, and 0-142 A in step-down), and voltage ripple (0.05%).