DC-DC type bidirectional high-frequency link DC for improved power quality of cascaded multilevel inverter

Multilevel inverters are important for power electronics applications and have become attractive in the power industries. It can be applied in many applications especially on improvement of the power quality such as in renewable energy sources, flexible AC transmission systems, uninterruptible power supplies and active power filters. Usually, a transformerless battery energy storage system based on a cascaded multilevel inverter, is used as a measure for voltage and frequency deviations. System can be reduced in size, weight, and cost of energy storage system. This paper presents a DC-DC type bidirectional high-frequency link DC (HFLDC) cascaded multilevel inverter. Each converter cell implements a control strategy for two H-bridge inverters that are controlled with the same multi-carrier pulse width modulation (PWM) technique. The proposed cascaded multilevel inverter generates lower voltage total harmonic distortion (THD) in comparison with conventional cascaded multilevel inverter. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of the proposed cascaded multilevel inverter.