Performance Improvement of Z-Source Inverter-Fed Induction Motor Drives Using Modified Voltage Space Vector

Abstract

In traditional Z-source inverter (ZSI) fed induction motor drives, the Z-source capacitor voltage and the motor terminal voltage are controlled by the shoot-through duty ratio and the modulation index, respectively. Modified voltage space vector has been proposed to improve motor terminal voltage control with effective DC boost in the DC link. For the same shoot-through duty ratio, modified voltage space vector provides better voltage boost in the DC link with reduced harmonics in the load side than the traditional voltage space vector. This paper presents an integrated control technique to minimise the electromagnetic torque ripples in the rotor of the ZSI-fed induction motor drives using modified voltage space vector. To improve the stability of the overall drive system, the motor terminal voltage alone is sensed instead of sensing the Z-source capacitor voltage and motor terminal voltage independently. This provides a single-stage controller for motor drive systems. The proposed induction motor drive system provides a better ride-through capability during voltage sags, better line harmonic profile, and minimisation of the torque ripples in the rotor. The proposed control technique is simulated using MATLAB/Simulink software, and analysis and experimental results have been presented to validate them.