This study aims 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 (SiC) power device. The primary challenge of this work is 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 aims for capacitive isolation. Subsequently, we devise a nesting capacitor as a short-circuit prevention measure. We report the isolated circuit configuration and operating principle.
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