Computationally Efficient Optimization of a Five-Phase Flux-Switching PM Machine Under Different Operating Conditions

Abstract

This paper investigates the comparative design optimizations of a five-phase outer-rotor flux-switching permanent magnet (FSPM) machine for in-wheel traction applications. To improve the comprehensive performance of the motor, two kinds of large-scale design optimizations under different operating conditions are performed and compared, including the traditional optimization performed at the rated operating point and the optimization targeting the whole driving cycles. Three driving cycles are taken into account, namely, the urban dynamometer driving schedule (UDDS), the highway fuel economy driving schedule (HWFET), and the combined UDDS/HWFET, representing the city, highway, and combined city/highway driving, respectively. Meanwhile, the computationally efficient finite-element analysis (CE-FEA) method, the cyclic representative operating points extraction technique, as well as the response surface methodology (in order to minimize the number of experiments when establishing the inverse machine model), are presented to reduce the computational effort and cost. From the results and discussion, it will be found that the optimization results against different operating conditions exhibit distinct characteristics in terms of geometry, efficiency, and energy loss distributions. For the traditional optimization performed at the rated operating point, the optimal design tends to reduce copper losses but suffer from high core losses; for UDDS, the optimal design tends to minimize both copper losses and PM eddy-current losses in the low-speed region; for HWFET, the optimal design tends to minimize core losses in the high-speed region; for the combined UDDS/HWFET, the optimal design tends to balance/compromise the loss components in both the low-speed and high-speed regions. Furthermore, the advantages of the adopted optimization methodologies versus the traditional procedure are highlighted. SECTION I. Introduction As the most important component in the traction system of electric vehicles (EVs), electric machines should be designed to have high torque density to provide the required acceleration capability in the low-speed region, and high flux-weakening capability to expand the constant-power speed range in the high-speed region. Compared to the conventional machine topologies commonly used in this application, e.g., induction motors [1], switched reluctance motors [2], and permanent magnet synchronous motors (PMSM) [3], flux-switching permanent magnet (FSPM) machines have attracted more attention due to their simple and robust rotor, high torque density, and favorable thermal dissipation [4]. Recently, FSPM machines with various configurations such as original configurations [5], C-and E-core configurations [6], have been presented for a diversity of applications. However, most of these configurations are limited to three-phase inner-rotor machines. Multi-phase motors have shown advantages in terms of their fault-tolerance capability, low torque pulsation, and additional degrees of freedom in the associated control sy...

Parametric Sensitivity Analysis and Design Optimization of an Interior Permanent Magnet Synchronous Motor

“…The cost function is expressed by eq. (11), in which the ferromagnetic materials of the stator and rotor are set up as the base/unity value for all materials and the cost ratios are selected as typical values for high volume production [10].…”

“…They exhibit wide constant power speed region (CPSR) and good mechanical integrity, which are suitable for high-speed application. However, the low PM material utilization in flux-switching PM motors would increase the cost significantly [10]. In order to meet the requirements in both the low-speed range and the high-speed range simultaneously, interior permanent magnet synchronous motors (IPMSMs) whose PMs are embedded in the rotor are considered to be very promising candidates [11]- [13].…”

Sensitivity analysis and multiobjective design optimization of flux switching permanent magnet motor using MLP‐ANN modeling and NSGA‐II algorithm

“…Recently, papers in the optimization of the FSPM motor are focused on the capabilities of this structure for use in electric vehicle application. 1, 28 In Reference 28, Chen et al using RSM model and GA the geometry optimization of the five‐phase FSPM motor considering drive cycle is carried out. In Reference 29, using MLMO approach the outer rotor FSPM motor is modified to maximize the torque meanwhile reducing the torque ripple and obtaining high efficiency.…”

Computationally efficient steady‐state finite element simulation of multiphase PM AC machines

“…Time course symmetry, on the other hand, exploits the periodic behaviour of the machine magnetic and electric circuits with regard to rotor angular displacement in the steady state [6–8]. When time course symmetry is applied to FE simulation of electrical machines, time savings are achieved by decreasing the value of simulated angular displacement [1–13]. This means that the waveform of magnetic flux density in one stator tooth can be reconstructed from segments of flux density waveforms in all other teeth that are obtained from FE simulations conducted over a minimum electrical angle [1, 3, 4, 10].…”

“…Nevertheless, specific equations for phase waveform reconstruction in [11] were again derived only for three‐phase machines. Equations for reconstructing steady‐state flux linkage waveforms for all phases of a five‐phase flux switching PM machine are derived in [12, 13] where full period waveforms are obtained from six or 12 magnetostatic FE solutions within a simulated angle of 36 or 72 electrical degrees, depending on whether even‐order harmonics exist or not.…”