Design of Flyback-Based Multiple Input Multiple Output Auxiliary Power Supply with Input Selecting Methodology

The proliferation of isolated bidirectional converters at various power levels for applications such as battery charging, direct current (DC) power transmission and electric vehicle (EV) drive trains have made the isolated auxiliary power supply a key component of a functional design. These auxiliary power supplies can range from simple, capacitor-based solutions to full-fledged low-power converters. This paper details the design of one such flyback-based auxiliary supply for a single-phase solid-state transformer (SST), which can be incorporated in any isolated bidirectional converter owing to its wide input voltage range, multiple isolated outputs, and input selection methodology. The system has been designed as part of an SST to meet the requirements of IEEE International Future Energy Challenge (IFEC) 2023. It incorporates two inputs, one on either port of a two port isolated converter, and can autonomously select which port to draw power from based on how the converter is plugged in. This permits the system to source auxiliary power irrespective of the direction of power flow or startup source and enables plug-and-play operation of the main power circuit.