Comparison of Multilevel and Differential Inverters: A Case-Study Concerning Complexity, Power Quality, and Efficiency

Abstract

Emerged power inverter structures with their PWM techniques have been presented to improve the output power quality, system loss, and efficiency, including sinusoidal-PWM (SPWM), space vector PWM (SVPWM), and harmonic injection techniques. Single-stage inverters exhibit compact, competitive-cost, and high power-density structures compared to the two-stage inverter architectures. The isolated multilevel inverter (MLI) and differential inverter (DI) are two single-stage inverter topologies for sinusoidal output-voltage synthesis. MLIs utilize a combination of switches at the front end of an H-bridge circuit. In the MLI, the required number of switches and power components increases for voltage boosting and enhanced output power quality. DIs are bidirectional inverters that comprise identical DC-DC modules, i.e., buck, boost, buck-boost, for voltage bucking and boosting capability. The DC-DC converter modules are differentially controlled so that the difference between their outputs forms the sinusoidal output-voltage waveform at the power frequency. This paper presents a comparison between isolated single-phase (1Φ) MLI and flyback-based DI. Both inverters’ component counts, power quality, and efficiency are compared considering the same load requirements of 1 kW, 220 V.