Wavelet Modulation With an Optimized Resolution-Level to Minimize Common-Mode Voltages in Variable Frequency Induction Motor Drives

This article presents the employment of the wavelet modulation with an optimized resolution-level to minimize the common-mode voltage (CMV) in variable frequency induction motor drives. The optimization of the resolution-level approach allows adjusting the duration and location of each ON switching pulse generated by the wavelet modulation technique. Such adjustments can significantly reduce the energy allocated in the harmonic contents of stator voltages, thus minimizing the instantaneous unbalance in the 3_ stator voltages. As a result, the CMV and current can be minimized without additional filtering circuits and/or modification of the power converters comprising the drive. The proposed method to minimize the CMV is experimentally tested using a 10hp induction motor frequency drive under various operating conditions. Test results show that optimizing the resolution-level has negligible impacts on control actions to operate the motor and/or dc link voltage.