Sung-Geun Song

Zero-voltage and Zero-current Switched Fuel-cell Powered DC-to-DC Converter

This paper presents a novel efficient fuel-cell powered converter. The power converter requires a special circuit configuration and control techniques to compensate the wide voltage variation because the output of fuel-cell has broad voltage ranges. So the proposed converter integrates a buck converter with a push-pull converter to be suitable for the fuel-cell as an input source. In addition, to increase the system efficiency each converter employs an auxiliary circuit for zero-voltage and zero-current switching. Operational principle is given in detail. The validity of the proposed fuel-cell powered converter is verified by experiments based on a 1 [kW] grid-connected prototype.

A Study on Novel PWM HBML Inverter Using Common-arm

In this paper, we proposed an electric circuit using one common arm of H-Bridge Inverters to reduce the number of switching component in multi-level inverter combined with H-Bridge Inverters and transformers. And furthermore we suggested the new multi-level PWM inverter using PWM level to reduce THD (Total Harmonic Distortion). We used the switching method that can get the same rate of usage at each transformer. We tested the proposed prototype 9-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi-level PWM inverter.