Selection Criteria and Robust Optimization of a Traction PM-Assisted Synchronous Reluctance Motor

Abstract

Abstract-In the coming years, the electrification and the deployment of the electric motors in the urban transports will become a reality more and more widespread. The optimization stage of the electric motors usually does not consider in detail the real driving conditions of the car in which the motor is installed. It follows that the actual motor performance in operating points, especially as regards the torque ripple and the efficiency, might be worsen than expected. A robust solution is a required target. This paper deals with the design and optimization of a high speed permanent magnet assisted synchronous reluctance motor for traction applications, taking into account of both city and highway driving cycles. A procedure is employed in order to evaluate the most representative operating points, which have to be considered for the global optimization. An analysis of the robustness of the solutions has been performed. Both results and advantages of the adopted methodology are highlighted. I. INTRODUCTIONThe progressive electrification of the private transport systems is becoming a well-established reality in the international scenario since it is seen as the most promising solution to reduce air pollution, oil dependency and to improve energy efficiency. As for convention internal combustion engine (ICE) vehicles, the performance of an electric vehicle are strictly related to the driving conditions of the car in which the motor is installed. On the other hand, the optimization procedure of the electric motors does not often consider the actual working conditions. For this reason, when the machine works, it becomes mandatory to optimize the design in the most profitable areas in which the motor operates, in order to improve the overall performance. On this basis, some recent researches [1]-[4] have introduced new design and optimization techniques for traction motors, in order to enhance the efficiency against a defined driving cycle. On the other hand, previous researches have investigated neither the optimization of the torque ripple, nor the robustness of the solution, over the aforementioned driving cycle. This paper aims to present an optimization procedure of a Permanent Magnet Assisted Synchronous Reluctance (PMASR) motor for traction application, considering a city and a highway driving schedule. The motor is equipped with a 36-slot 4-pole and an integral-slot distributed winding. A high grade Ferrite PM is considered. The interest in Ferritebased PMASR motors [5]-[8] is spreading in the last years, as a consequence of the instability and the increase of the price of rare earth magnets. Moreover, it provides a high flux weakening operating range, which is usually an important requirement in traction applications. Conversely, the most

Performance Comparison of Conventional Synchronous Reluctance Machines and PM-Assisted Types with Combined Star–Delta Winding

“…A shown before, the maximum output torque of the four machines is different and the Sd-PM machine gives the highest output torque. In general, and in correspondence with the literature [15], adding ferrite PMs in the rotor of a SynRM increases the machine's efficiency. It is worth noting that the efficiency of the Sd-PM machine (Figure 30) is much better than for the other machines over the whole operating range, but especially at low loads.…”

“…In the literature, much research work on SynRMs and PMaSynRMs can be found [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. For example, in [8], SynRM performance is compared for different electrical steel grades.…”

“…Eventually, the overall machine performance is improved compared to the conventional rotor design. A design and optimization of a high speed PMaSynRM for traction applications is investigated in [15]. The study takes into account both highways and city driving cycles.…”

Comparative Study of Ipm Synchronous Machines With Different Saliency Ratios Considering Evs Operating Conditions

“…Currently, some articles have reported the design of machines under different operating conditions [12][13][14][15]. In [12], the dynamic behaviors of a permanent magnet synchronous machine are investigated in which three different operation conditions such as no load, rated operation, and short circuit are analyzed.…”

“…In [13] and [14], by considering the limitation of different load current, the robustness against demagnetization of an ferrite assisted synchronous reluctance machine is studied, and the investigations show that the larger machines have more risk of demagnetization than smaller ones when overload current is applied. In [15], the optimization design of PM synchronous machines is performed to reduce the losses in high speed operation condition, and the methods enlarging operating efficiency especially in high speed light load region are proposed. In summary, the operation characteristics of machines in various operating conditions have been studied extensively.…”