Correction of Current Measurement Scaling and Offset Errors for Permanent Magnet Synchronous Machine Drives

Current measurement errors in permanent magnet synchronous motor (PMSM) drives can lead to undesired torque and speed ripples, significantly impairing control performance. To address this issue, this paper presents a novel online current error correction method for PMSM drives. The proposed approach takes into account both current scaling errors and offset errors, aiming to achieve precise error correction without relying on signal injection or prior knowledge of machine parameters. First, the relation between the different types of current errors and the machine speed harmonic is derived, laying the foundation for current measurement correction. Then, the speed harmonic is explored to search for actual current errors with the gradient descent algorithm. By minimizing the specific order of speed harmonics, the proposed algorithm achieves precise correction for current measurement errors without signal injection or knowledge of machine parameters. Through extensive simulation studies, the efficacy of the proposed current error correction algorithm is thoroughly validated. The results demonstrate significant improvements in control performance, confirming the method's ability to mitigate both current offset and scaling errors in a PMSM drive.