Novel Six-Step and Twelve-Step Current-Source Inverters with DC Side Commutation and Energy Rebound

Novel six-step and twelve-step current-source inverters (CSI) with dc side commutation and energy rebound capability are presented with detailed explanation of the circuit operation. The proposed inverters can operate in a very wide range of frequency and load variation by employing dc side commutation. Also, the energy rebound makes the use of low voltage silicon controlled rectifiers (SCR´s) possible and increases the inverter efficiency. Unlike the dual current-source inverter, one auxiliary inverter with a power requirement of about one-half that of the main inverter is simply added to the six-step CSI in order to obtain a twelve-step CSI. Motor operation is possible in four quadrants in both six-and twelve-step inverters. The advantages of the proposed CSI´s over conventional ones are described, and experimental results are given in oscillograms.