Integrated current balancing cells based IPOP bidirectional CLLC resonant converter modules for high-power applications

This paper proposes an integrated current balancing (ICB) cells-based input parallel output parallel (IPOP) bidirectional CLLC modules. The IPOP system based on the CLLC modules inherent all of the good features of a single CLLC module including zero-voltage and zero-current switching (ZVZCS) for the inverter and rectifier stage. Besides, the IPOP configuration is a better approach to utilize low-power rating modules for high-power applications. However, tolerances in the tank circuit parameters cause an acute imbalance in modules currents. Therefore, the equal power distribution among the IPOP CLLC modules is an important issue that needs to be addressed. Different control and passive current sharing techniques have been proposed, but they cause increase in component count, cost, complexity, and magnetic volume of the IPOP converters. This paper integrates the already present resonant inductors of the bidirectional CLLC modules to evenly share the two currents at the input as well as at the output of the converters under the open-loop condition with substantial tolerances of (Formula presented.) in the tank circuit parameters. Moreover, the proposed ICB cells generate sufficient resonant inductances for the respective tank circuits, simultaneously. No additional active or passive components are introduced in the system; thus, it does not increase the cost, complexity, and magnetic volume of the IPOP CLLC modules. Two types of cores (UU- and EE-cores) based ICB cells are analysed with current sharing performance. To verify the effectiveness of the ICB cells, a 4.9-kW laboratory hardware prototype was built and tested.