The Development and Performance Testing of a $V/f$ Control for Induction Motors Fed by Wavelet Modulated Power Electronic Converters

Volt-per-hertz ($V/f$) scalar control is one the simplest control structures developed for operating induction motor drives. This paper presents the development and performance testing of a $V/f$ scalar control for induction motor drives that are fed by $3\phi$ wavelet modulated dc-ac power electronic converters. The wavelet modulation technique is typically characterized by the maximum resolution level ($J$) and scale-time interval factor ($\gamma$). The magnitude of the output voltage of a three phase wavelet modulated inverter is directly dependent on $J$, while the number of switching pulses, over a half cycle of the output voltage, is related to $\gamma$. These two factors of the wavelet modulation technique can be adjusted to implement a $V/f$ scalar control of induction motor drives. The $V/f$ scalar control of a wavelet modulated dc-ac PEC is implemented for performance testing using induction motor drives under different operating conditions. Performance results demonstrate stable, dynamic, and accurate responses, with minor sensitivities to the load torque and/or initial and final speeds. Furthermore, test results demonstrate the ability to enhance the efficiency using the tested scalar control.