Comparison between two inverter topologies for application in industrial drives

In this paper the steady state characteristics of slip energy recovery drives (SERD) employing a three phase bridge recovery inverter (topology "A"), are compared with the characteristics of SERD employing three, single phase bridge inverters operating in the flywheel mode (topology "B"). The comparison comprises the waveforms of voltages and currents of the stator, rotor, DC link, inverter output, and recovery transformer output. For accurate and fair comparison, the turns ratio of the recovery transformer used with each inverter topology is calculated on the basis of equal speed ranges for the drives employing them. The harmonics injected into the grid, and the power factor of the system employing inverter "A" are compared with those of the system employing inverter "B". Experimental results are given for the SERD employing the three single-phase inverters topology. These results verified the theoretical analysis.