Parameter Optimization for Reducing Torque Ripple and Harmonic Losses of Multi-Layered Interior Permanent-Magnet Synchronous Motors

Abstract

In this paper, parameter optimization of multi-layered interior permanent-magnet synchronous motors for electric vehicle propulsion is carried out to improve torque ripple and efficiency at low-and high-speed regions. First, we establish a torque ripple map based on d-q currents. The ripples of the d-q parameters and harmonics of the phase flux linkages are then analyzed to investigate the relationship between the torque ripple and the parameters. Second, we compose and analyze an iron loss map based on d-q currents, and then investigate the parameters that affect the harmonics of the flux density. In particular, because the high-speed region is highly vulnerable to iron loss, the parameters related to this tendency are also analyzed. Based on the analysis results, we develop a parameter optimization strategy that leads to an optimal design. To analyze the electro-magnetic performances of the motors, two-and three-dimensional finite elements analyses are carried out by employing sinusoidal and inverter-controlled currents, and the improvement achieved are demonstrated by the experimental validations on prototypes.INDEX TERMS Efficiency, iron loss, low-and high-speed regions, multi-layered interior permanentmagnet synchronous motors, parameter optimization, torque ripple.

Model Validation of Synchronous Motors With a New Standstill Measurement Technique

“…However, it is challenging or even impossible to measure precise torque ripple of a rotating rotor at different current vectors (referred to the rotor reference frame) as well as inductance variations of the machine at different rotor positions (including inductances along d-and q-axes). For this reason, most of the literature dedicated to the analysis of torque ripple phenomenon does not have actual verification of torque ripple results with measurements [10]- [12]. The same is valid for the exact inductance values of the machine, when the actual average inductance (over the complete electrical period) can be directly measured either only at one current vector angle (e.g.…”