Torque riplle reduction of permanent magnet machine with model based current reference control

Permanent magnet synchronous machines (PMSM) is preferred in many applications due to its advantages. However, torque ripple of PMSM has been a critical issue especially in precise servo applications. It is very important to estimate torque ripples to achieve robust torque, speed or position control. In industry, torque estimation is generally implemented in an approximate manner and it is aimed to control the average value of the torque. The average torque estimation method is not suitable for precise torque control. Torque ripple modeling and minimization for PMSMs require accurate information of the inductances, flux linkages and cogging torque which vary nonlinearly. This paper proposes an analytical estimation model for PMSM torque ripple minimization. The proposed torque estimation takes into account the variation of the machine parameters. Machine parameter variations of the PMSM to used in the proposed method are analyzed in 2D with the finite element program. Analytical equations are utilized to estimate the resultant torque ripples due to the variations of magnet flux, d-q axis inductances, and the cogging torque and the proposed estimation method occurs successful results. Thanks to the successful estimation model, reference currents are determined with a novel calculation method for suppress torque fluctuation. The proposed approach reduces computational burden and gives impressive results. By using the advanced motor model, reference currents which reduce the torque ripples are calculated for torque control of PMSM. This paper presents an advanced analysis method for the proposed precision torque control. The proposed advanced coupled simulation model occurs multiple professional analysis programs working together. If the suitable analysis method is not used, errors occur in the control method due to the data delay between the analysis programs. Therefore, this paper compares the performance of the proposed co-simulation model at various sampling times, it presents the solutions of simulation errors and it is contributed to literature by proposing the most accurate analysis model. Accuracy of the torque control system has been validated by finite-element modeling, analytical calculations, and advanced coupled simulation analysis.