A Five‐Level Active Neutral‐Point‐Clamped Auxiliary Inverter Based on Reverse Blocking IGBT in Metro Applications

ABSTRACT In recent decades, multi‐level inverter such as a five‐level inverter has gained much attention for its high equivalent switching frequency and low voltage stress. This paper proposes a novel five‐level active‐neutral‐point‐clamped converter utilising reverse blocking IGBT (RB‐IGBT), targeting auxiliary power supply in high‐speed train and metro system. Compared to the conventional five‐level inverters, the proposed inverter configuration exhibits lower conduction loss. Unlike the five‐level topologies of previous inverters, only two switches are on the current paths in the designed inverter, leading to the reduced conduction loss. Meanwhile, an optimised state machine‐based modulation strategy was proposed, which can implement reliable current commutation among adjacent states and maintain flying capacitor voltage balance within multiple carrier cycles. Furthermore, a detailed comparative analysis of loss breakdown and voltage stress characteristics in five‐level inverters were presented. Finally, a 27 kVA experimental prototype was built to verify the validity and feasibility of the proposed topology and modulation strategy.