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 electromagnetic-interference filter to eliminate switching voltage/current ripples and electromagnetic noise. The main circuit of the proposed circuit consists of a diode-clamped linear amplifier (DCLA) and a voltage balancing circuit. The circuit configuration of the DCLA is similar to a diode-clamped multilevel inverter, except for using complimentary MOSFETs as a power device. 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 total harmonic distortion of less than 2%.