Switching frequency variation over the entire operating speed range of an induction motor (IM) drive is the major problem associated with conventional two-level threephase hysteresis controller as well as the space phasor based pulse width modulation (PWM) hysteresis controller. This paper presents a new variable band hysteresis current controller for controlling the switching frequency variation in the two-level PWM inverter fed IM drives for various operating speeds. A novel concept of online variation of the band based on both the instantaneous load current and current change for each
sampling period is presented to determine the hysteresis band. A performance comparison of the proposed with conventional hysteresis current controller for IMdrive is provided in simulation. The proposed drive system is also implemented in real-time using DSP board DS1104 for a laboratory 1.5 hp motor. Comparative simulation and
real-time results verify the feasibility of the proposed scheme and demonstrate that the proposed method has obtained constant switching frequency and improved the performance of the drive system.