Investigations on variable and constant switching frequency hysteresis controller for VSI fed IM drive

Abstract

In various current controlled-pulse width modulated (CC-PWM) techniques which are extensively employed in high performance drives, hysteresis current control (HCC) offer significant simple implementation and good dynamic response. However, conventional HCC have drawbacks, such as, limit cycle oscillations, overshoot in current error, generation of sub-harmonic components in the current, and non-optimum switching of inverter voltage vectors which can create variable switching frequency. This work proposes a new constant switching current error space phasor (CESP)-based hysteresis controller with a simple online computation of the boundary and phase voltage harmonic spectrum similar to voltage controlled bus clamping PWM (VC-BCPWM)-based VSI fed induction motor drive. The error boundary computed using voltage and current errors in the present sampling interval is used for identifying next vector to be switched. The current controller using CESP approach is simulated using MATLAB Simulink and experimentally verified on 2.2 kW IM drive.