Automatic Current Sharing of an Input-Parallel Output-Parallel (IPOP)-Connected DC–DC Converter System With Chain-Connected Rectifiers

Input-parallel output-parallel (IPOP)-connected converter systems allow the use of low-power converter modules for high-power applications. An IPOP converter topology with half-wave, daisy chain-connected rectifiers is presented which consists of multiple half-bridge (HB) dc–dc converter modules. By utilizing a common-duty-ratio control scheme, without a dedicated current-sharing controller, automatic sharing of input current and load current in the IPOP converter is achieved even in the presence of differences of more than 10% in various module parameters. The steady-state and dynamic-state current-sharing performance of the proposed IPOP converter is analyzed by using a steady-state dc model and a small-signal model of the system, respectively. It is concluded that steady-state current sharing among modules can be realized by applying a common-duty-ratio control scheme and by reducing the difference in transformer turn ratios, while dynamic-state current sharing is only slightly affected by substantial module parameter mismatches. The stability and current-sharing performance are verified by Saber simulation and an 800-W prototype consisting of two HB modules. The IPOP converter topology under the common-duty-ratio scheme can be extended to any system of three or more converter modules, including full-bridge dc–dc converters.