A reduced switch transformer-less dual hybrid active power filter

This paper proposes transformer-less dual hybrid topologies suitable for rectifier type load. Performance of the reduced switch version of the network is highlighted. It consists of two inverters, one operates at a lower frequency (typically around 550 Hz) and the other operates at higher frequency (around 20 kHz). Less number of switches is used to improve reliability and reduce cost. The low frequency inverter is in series with a passive filter to optimally eliminate 5^th and 7^th harmonics, whereas the high frequency inverter is connected to a passive filter to optimally eliminate 11^th and 13^th harmonics in addition to the other harmonics of the load and any additional harmonics generated by the low frequency inverter. The usefulness of the proposed topology is confirmed by simulation and prototype experimentation in the laboratory.