Wavelet Modulated Inverters for Reducing Common-Mode Voltages in Variable Frequency Motor Drives

Variable frequency drives (VFDs) are widely used in various industrial sectors due to their operational and control advantages. Despite their several advantages, VFDs face challenges due to common-mode voltages (CMVs), which can cause physical damage to VFD components. Several studies recommend reducing the harmonic distortion in voltages applied to the motor stator windings. This paper presents and discusses performance evaluation of the wavelet modulation technique, when utilized to operate a VFD inverter in order to reduce CMVs. The wavelet modulation technique generates its switching pulses using sets of wavelet basis functions, which are generated to maximize the energy in specific (desired) frequency components. This feature of the wavelet modulation technique can be advantageous in reducing CMVs experienced by electric motors operated by VFDs. The ability of wavelet modulated inverter to reduce CMVs in VFDs, is experimentally tested using a $10 h p, 3 \phi$ induction motor VFD. Experimental test results show that a wavelet modulated inverter can offer significant reductions in CMVs, when compared with other inverters under similar operating conditions.