Active Voltage Sharing Module for Input-Series Connected Modular DC/DC Converters

Since both the input-series-output-series system and the input-series-output-parallel system have a circuit configuration in which the input sides are in series, it is very suitable for applications with high input voltages. This article proposes a simple active voltage sharing module (AVSM) that allows two closed-loop dc/dc converters to be combined directly into an input-series system as power devices to meet various voltage requirements. An AVSM, consisting of one coupled inductor and two metal-oxide-semiconductor field-effect transistors, is connected on the input side of the two submodules. By adopting a control method with fixed frequency and duty cycle, accurate input voltage sharing can be achieved, enabling voltage isolation sampling of the submodules and the voltage sharing regulators of the system to be eliminated, thus greatly simplifying the design process of the input-series system. This article introduces the AVSM working principle and discusses the stability of the proposed input-series system. It then describes a simulation performed to verify the theoretical analysis results and addresses the influences of the AVSM parameters on the system performance. Finally, the use of a prototype to test the steady-state and dynamic performances of the proposed scheme is discussed.