Experimental verification of isolation power circuit for transformer-less AC fed electric vehicles

Abstract

This study aimed to develop a power supply system without a traction transformer for weight reduction and downsizing. Transformer-less power supply is expected to realize step-down, rectification, isolation, and motor drive using a high-voltage silicon carbide power device. The primary challenge of this study was developing a novel circuit that isolates the motor drive circuit from the AC line without using the traction transformer. Accordingly, we devised a flying capacitor circuit to solve the existing problems and achieve capacitive isolation. Subsequently, we devised a nesting capacitor as a short-circuit prevention measure. In this study, the operation of the isolated circuit was verified by numerical simulation, complemented by experimental verification of the proposed circuit.