UPSC SVPWM controlled multi‐level inverter topology for multiple pole‐pair induction motor drive for minimising torque ripple

Abstract

The demand for multi-level inverters is increasing progressively in motor control applications. Many pulse width modulation (PWM) techniques are proposed in the literature and one of the popular modulation methods is unipolar phase shifted carrier (UPSC) PWM. This PWM technique is commonly used in uninterrupted power supply applications where transformer multiple primary windings are connected to two-level inverters. However, this modulation technique is not popularly used in drives applications because a conventional induction motor consists of only two terminals per phase. In this study, a multi-level inverter configuration for four pole induction motor drive is presented, where it is compatible to use the above mentioned PWM technique. By using this multi-level inverter configuration and UPSC PWM technique, all lower order harmonics are shifted to four times the switching frequency, which in turn reduces the torque ripple considerably. The proposed concept is tested on 5hp four-pole induction motor in MATLAB/Simulink and finite element analysis and is also experimentally verified with a laboratory prototype. The simulation and experimental results show the effectiveness of the proposed topology and demonstrate the improvement in harmonic profile and torque ripple.