Reduction of Torque Oscillations in Permanent Magnet Synchronous Machine Using Optimal Current Injection Based on Unbalanced Load Detection

Abstract

This article presents a comprehensive approach to addressing the challenges of unbalanced rotors in permanent magnet (PM) synchronous machines by proposing a load torque (LT) observer for unbalance detection and a current injection technique for minimizing torque oscillations resulting from the unbalanced rotor. The primary objective is to enhance the operational efficiency and performance of electric motors by identifying the effects of the unbalanced rotor on the motor torque. The proposed LT observer utilizes real-time speed measurement to estimate the total LT. To significantly reduce the torque oscillations from the unbalanced rotor, optimum current components are injected with meticulously calculated amplitude and phase. The proposed method operates in synchronization with the rotor position, and the injected currents are extracted via an optimization problem from an adaptive model that is continuously updated through a parameter's identification method. The effectiveness of the proposed approach is demonstrated through experimental evaluations on a representative experimental setup. The results reveal that the LT observer accurately detects rotor unbalance and the current injection technique successfully minimizes motor torque oscillations, resulting in smoother motor operation, reduced noise, and improved overall efficiency. © 1982-2012 IEEE.