الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
Hysteresis current control (HCC) is the simplest technique used to control the phase motor currents for high performance drive systems, because of its ease implementation, fast current control response, and inherent peak current limiting capability. However, the variable switching frequency of this scheme is undesirable since it deteriorates the system performance in terms of high switching losses and extra harmonic heating problem. This study has presented an improvement of HCC technique for VSI-fed IM drive in order to ensure a constant Switching frequency. This achieved by developing a new variable hysteresis band. The prediction of the proposed band is based on both the instantaneous load current and the load current change in the previous switching period. Then the algorithm calculates the new band in the next switching period to generate the switches pulses to establish the load current in this period.