Evaluation of Simplified Model for Rapid Identification and Control Development of IPM Traction Machines

This article presents an evaluation of simplified model considering only q-axis current effects on parameters for rapid identification and control development of interior permanent magnet (IPM) traction machines. It is shown that the identification of the simplified model is simple and easy to be implemented. It is demonstrated that in the low-speed region with maximum torque per ampere (MTPA) control, due to the flat segment around the MTPA point of the relevant constant torque over current magnitude curve, MTPA operation could still be achieved using the simplified model. It is shown that in the field-weakening (FW) region where the effects of parameter mismatch resulting in a higher-than-expected voltage magnitude could be mitigated via a voltage feedback (FB) loop, torque-speed performance still could be obtained with a reduction in the torque-speed boundary together with up to 1.5% machine efficiency difference. Thus, the simplified model could be considered at the earlier stage of identification and control development as a rapid solution to quickly test and validate IPM machine design/manufacture when the validation of the complex model considering the effects of both dq-axis currents is highly time-consuming. The simplified model is validated via measurement on a high-speed high-power (15 000 r/min, 120 kW) IPM traction machine.