Improved Selective Harmonic Elimination for Reducing Torque Harmonics of Induction Motors in Wide DC Bus Voltage Variations

TL;DR

This paper introduces an improved selective harmonic elimination method that optimizes switching angles to reduce torque harmonics in induction motors, especially under wide DC bus voltage variations, enhancing motor performance.

Contribution

The paper presents a novel optimization approach for SHE that accounts for wide voltage variations and load conditions, improving harmonic torque reduction in induction motors.

Findings

Effective harmonic torque reduction demonstrated in simulations.

Method adapts to wide voltage and load variations.

Improved motor performance under diverse conditions.

Abstract

Conventionally, Selective Harmonic Elimination (SHE) method in 2-level inverters, finds best switching angles to reach first voltage harmonic to reference level and eliminate other harmonics, simultaneously. Considering Induction Motor (IM) as the inverter load, and wide DC bus voltage variations, the inverter must operate in both over-modulation and linear modulation region. Main objective of the modified SHE is to reduce harmonic torques through finding the best switching angles. In this paper, optimization is based on optimizing phasor equations in which harmonic torques are calculated. The procedure of this method is that, first, the ratio of the same torque harmonics is estimated, secondly, by using that estimation, the ratio of voltage harmonics that generates homogeneous torques is calculated. For the estimation and the calculation of the ratios motor parameter, mechanical speed of the rotor, the applied frequency, and the concept of slip are used. The advantage of this approach is highlighted when mechanical load and DC bus voltage variations are taken into consideration. Simulation results are presented under a wide range of working conditions in an induction motor to demonstrate the effectiveness of the proposed method.