A New Direct Torque Control Scheme for Five Phase Open-end Winding Induction Motor Drives with Reduced DC Voltage Requirement

A direct torque control (DTC) scheme for five phase induction motor drives with open-end stator winding configuration is presented in this paper. The DTC scheme proposed here make use of the non-adjacent line voltage vectors that are generated as resultants of the voltages produced in the two inverters. The method of generation of voltage vectors proposed in this paper does not produce common mode voltage across the motors windings. Both the inverters can be fed from a single DC source with a common DC link without any common mode current flow. Another important aspect of the proposed scheme is that it makes the average voltage produced in the non-torque producing plane (x-y plane) zero thereby preventing the flow of large harmonic currents through the windings. Also, this scheme can reduce DC voltage requirement by 47% when compared to that of a single–end inverter fed, star connected five phase induction motor drive for the same phase voltage. The proposed DTC scheme is verified experimentally using a laboratory prototype under both steady state and transient operating conditions.