A Single-Phase Utility-Interface Circuit without any AC Inductor nor EMI Filter

This paper proposes a single-phase utility-interface circuit without any ac inductor nor EMI filter to eliminate switching voltage/current ripples and electro-magnetic noises. The main circuit of the proposed circuit consists of a diode-clamped linear amplifier (DCLA) and a voltage balancing circuit. The DCLA has a circuit configuration similar with a diode- clamped multi-level inverter, except for using complimentary MOSFETs as the power devices. As a result, the DCLA makes it possible to generate a sinusoidal output voltage without any ac filter. This paper presents new control methods of the output voltage and current to connect the DCLA with the utility grid. The experimental results show a power conversion efficiency as high as 93% and a current THD less than 2%.