Input-series and output-parallel connected single stage buck type modular AC-DC converters with high-frequency isolation

An input-series-output-parallel connected single stage buck type modular AC-DC converter with high-frequency isolation is presented in this study. The configuration possesses the following characteristics: (i) single-stage conversion, (ii) high-frequency isolation, (iii) using low voltage rating power devices. A stable control strategy based on the analysis of the three working states is proposed to achieve input voltage sharing automatically through output current sharing without sampling input voltages. With the strategy, equal power sharing can be obtained in both steady and dynamic state, even in the case when the parameters of individual modules are mismatched. The control loop modelling and design are given to show the stability of the control scheme and design of the controllers. The effectiveness of the presented topology and proposed control strategy are verified by simulations and experimental results.