Circuit Configuration and Modulation of a Seven-Level Switched-Capacitor Inverter

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.

Automated summary

This article presents a step-up seven-level inverter suitable for renewable energy applications, featuring sensorless voltage balancing of capacitors and generation of bipolar staircase waveforms. The inverter benefits from regenerative performance and prevents unwanted capacitors overvoltage. Experimental results confirm the performance of the proposed inverter and the validity of its design, reaching a maximum efficiency of 94.3% under specific load conditions.