Control Strategy for Input-Parallel Output-Series Connected Inverter Systems

Abstract

Input-parallel output-series(IPOS) connected inverter systems, constructed from connecting multiple inverter modules in parallel at the input side and in series at the output side, are very suitable for high output voltage and high power dc-ac conversion applications. In order to make the IPOS systems work normally, the input current sharing(ICS) and output voltage sharing(OVS) among the constituent modules should be ensured. By analyzing the relationship of the ICS and OVS in terms of power conservation, this paper proposes a compound control strategy, which can achieve ICS and OVS simultaneously. Then a practical realization of the compound strategy, namely, three-loop control scheme, is proposed. This control scheme achieves ICS and phase synchronization of the module output voltage. Decoupling of the control loops is also presented. Finally, the simulation results are given to verify the effectiveness of the compound control strategy.