High Frequency Current-Fed Isolated Auxiliary Power Supply for Medium-Voltage Converter

In this paper, a high frequency current-fed isolated auxiliary power supply (HFCF-APS) is proposed for medium-voltage module stack converters. Unlike conventional anxiliary power supplys (APSs), the proposed HFCF-APS can realize galvanic isolation with a single high-voltage insulation cable. The HFCF-APS can flexibly extend its output number as the converter needs. Two secondary compensation topologies, capacitor-inductor (CL) and capacitor-capacitor (CC), are proposed to allow the HFCF-APS to extend the output number wide range without modifying circuit parameters and losing the soft-switching conditions of the power switches on the primary side. Moreover, two logical control circuits corresponding to the CL and CC compensation topologies are designed with a few additional components. As a result, all output channels are immune to load short and open circuits, so the reliability of the HFCF-APS is improved. To demonstrate the validity of the proposed HFCF-APS, simulations and experiments of an HFCF-APS prototype of 8–12 channels with 10 W output each are carried out. The results verify the extendibility and reliability and indicate that the proposed HFCF-APS offers a superior solution for multi-output APS.