Four-Stage Cascaded Predictive Control for Zero-Sequence Current Suppression of Open-End Winding Induction Motor

A four-stage cascaded predictive control method is proposed in this paper to suppress the zero-sequence current (ZSC) of the open-end winding induction motor (OEWIM). ZSC is generated when a single DC source feeds two inverters of an OEWIM. Circulation of ZSC in the motor windings increases the torque ripple and deteriorates the stator current waveform. The proposed method eliminates the ZSC by cascaded control of two inverters. By using voltage vectors of one inverter, the first and second stages control the torque and stator flux, respectively. Voltage vectors of the other inverter are used in third and fourth stages to eliminate ZSC beside the controlling stator flux and torque. In comparison to the conventional predictive control of OEWIM, this strategy won't impose an excessive burden on the control system. Moreover, the weighting factor of the stator flux is removed from the cost function. A comparison is made between the proposed strategy and the conventional method in simulations. Results show the superior performance of the proposed cascaded predictive control.