Torque ripple reduction method of permanent magnet synchronous motor by current sensor gain unbalance correction

This paper presents a new algorithm, which corrects gain unbalances of current sensors, applied in a conventional two-phase current detection for adjustable speed drive system of IPMSM. The gain unbalance of current sensors is corrected by utilizing the second harmonic components which is extracted by Discrete Fourier Transform (hereafter DFT) from q-axis voltage command. Besides, the correction process is performed in synchronization with the process of DFT. The validity of the proposed method is confirmed by experimental results. The torque ripples of the second harmonic components caused by the gain unbalance of current sensors is reduced by 94%.