Design and implementation of adaptive hysteresis current control based power quality studies for an induction motor

This paper presents a new control strategy for adaptive hysteresis current control based power quality studies for an induction motor to eliminate harmonics and to compensate the reactive power. The adaptive hysteresis band current controller changes the hysteresis bandwidth according to modulation frequency, supply voltage, dc capacitor voltage and slope of the reference compensator current wave. The large rating of three phase induction motor take very large low power factor currents while being started directly from a 3-phase supply. Normally soft-starts are used for avoiding this problem and to achieve smooth starting of large capacity induction motors. A three phase AC voltage controller is employed as a soft-start. But, this takes harmonic-rich current especially while operating at large firing angles. The adaptive hysteresis current control based shunt active filter has been inserted between the AC voltage controller and power supply to take care of the reactive power requirement of the motor, AC voltage controller and also to provide harmonic compensation. In shunt-active filter uses the Synchronous Reference Frame (SRF) theory to determine the suitable compensation currents. The simulation has been carried out through the MATLAB Simulink SimPowerSystems Toolbox and Hardware work has been done on a 22 kW induction motor with and without soft-start arrangement.