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

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.