Dual‐input step‐up switched‐capacitor multilevel inverter with reduced voltage stress on devices

Abstract

SummaryThis paper proposes a single‐phase dual‐input step‐up switched‐capacitor multilevel inverter that employs three capacitors, 15 switches, and two diodes to provide 13 voltage levels and triple‐voltage boosting factor in its symmetric form and 37 levels with voltage boosting factor of 3.6 in its asymmetric version. This high boosting factor is accomplished without utilizing any transformer. For each output voltage level, there exists flow paths for both the positive and negative load current directions, which makes the proposed inverter capable of supplying any load type with variety of power factors (zero to unity). The voltage balancing of the capacitors takes place naturally, which tackles the need to auxiliary charge‐balancing circuits or control mechanisms. The proposed inverter can generate negative levels without the end‐side H‐bridge. Moreover, the voltage stress on the semiconductor devices is less than the peak output voltage. The increased number of levels and sinusoidal‐like waveform of the output voltage waveform enhances the quality and lowers the harmonic content of the load voltage and current waveforms, even for resistive loads. As the result, the load‐side filter can be downsized or removed. This paper employs the fundamental frequency method (FFM) as the switching technique, which is simple to implement and also operates the switches at low frequencies, leading to lower switching losses. The ascendancy of proposed inverter over similar counterparts has been investigated through comprehensive comparative analysis. Moreover, the correct performance of the proposed inverter at different modulation indices, and load types as well as during dynamic load changes has been verified by simulation and experimental analysis.