Development Of SVPWM Common Mode Voltage Suppression Techniques In Dual-Inverter Fed Six-Phase Open-End Winding PMSM Drives

This thesis proposes a space vector modulation algorithm for an asymmetrical six-phase open-end winding permanent magnet synchronous motor(OEWPMSM)supplied by two two-level six-phase voltage source inverters(VSIs)with common mode voltage suppression.Two topologies are investigated.The first topology consists of the dual inverter with separated DC supplies,and the second topology is the dual-inverter fed from a single DC source.A six-phase open-end winding PMSM with open-end windings model is developed based on the vector space decomposition(VSD)technique.The voltage concept,namely,common mode voltage(CMV)is investigated on both topologies and its effect on the drive system such as motor shaft voltage;zero sequence current and common mode current are presented.A space vector pulse width modulation(SVPWM)method is then proposed which is capable of not only suppressing the current harmonics in non-torque producing sub-spaces,but also eliminating the CMV.The switching states providing zero CMV are identified and the corresponding space vectors are determined.In the proposed scheme,two two-level six-phase space vector modulators are utilized,where the resultant reference voltage is decomposed into two components and each component is controlled independently.The performance of the proposed PWM technique is evaluated using total harmonic distortion of motor voltage and current,the current components in different sub-spaces and a comparison in CMV profile between conventional SVPWM and the proposed SVPWM is provided using Matlab/Simulink software.