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 <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\textbf{3}\boldsymbol{\mathbf{\phi}}$</tex-math></inline-formula> 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 10<bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>hp</i></b> 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.