부산대학교 도서관

In this article, a step-up seven-level inverter supplied by a single dc source suitable for renewable energy application is presented. Forming the desired output is realized by charging capacitors and synthesizing them based on a switched-capacitor concept. This structure is praised for the ability of sensorless voltage balancing of the capacitors, reducing control complexity to produce a bipolar staircase waveform. It also benefits from regenerative performance, avoiding unwanted capacitors overvoltage. A phase disposition pulsewidth modulation (PD-PWM) technique is utilized to control the circuit operation. Furthermore, a comparison with other recent topologies reveals that losses, number of semiconductor devices, and gate driver circuits are reduced. Theoretical analysis is verified through a laboratory prototype implementation. Experimental results under various types of loads approve the performance of the proposed inverter and validity of the design. Finally, maximum experimental efficiency of 94.3% (115 V, 250 W load) was reached.