Establishing the Relative Merits of Interior and Spoke-Type Permanent-Magnet Machines With Ferrite or &lt;roman&gt;NdFeB&lt;/roman&gt; Through Systematic Design Optimization

Ionel

et al. 2019

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A fast finite element (FE) based method for the calculation of eddy current losses in the stator windings of randomly wound electric machines is presented in this paper. The method is particularly suitable for implementation in large-scale design optimization algorithms where a qualitative characterization of such losses at higher speeds is most beneficial for identification of the design solutions that exhibit the lowest overall losses including the ac losses in the stator windings. Unlike the common practice of assuming a constant slot fill factor s f for all the design variations, the maximum s f in the developed method is determined based on the individual slot structure/dimensions and strand wire specifications. Furthermore, in lieu of detailed modeling of the conductor strands in the initial FE model, which significantly adds to the complexity of the problem, an alternative rectangular coil modeling subject to a subsequent flux mapping technique for determination of the impinging flux on each individual strand is pursued. Rather than pursuing the precise estimation of ac conductor losses, the research focus of this paper is placed on the development of a computationally efficient technique for the derivation of strand eddy current losses applicable in design optimization, especially where both the electromagnetic and thermal machine behavior are accounted for. A fractional-slot concentrated winding permanent magnet synchronous machine is used for the purpose of this study due to the higher slot leakage flux and slot opening fringing flux of such machines, which are the major contributors to strand eddy current losses in the windings. The analysis is supplemented with an investigation on the influence of the electrical loading on ac winding loss effects for this machine design, a subject that has received less attention in the literature. Experimental ac loss measurements on a 12-slot 10-pole stator assembly will be discussed to verify the existing trends in the simulation results.

Section: B Extraction Of Field Profiles Inside the Slotmentioning

confidence: 99%

Section: Section I Introductionmentioning

confidence: 99%

Computationally Efficient Strand Eddy Current Loss Calculation in Electric Machines

Ionel

et al. 2019

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“…The CE-FEA concept has also been utilized to calculate the rotor magnet losses of concentrated-winding PM synchronous machines [4]. The design optimization method based on CE-FEA and DE has since been used to identify the existing trade-offs in multiobjective design of PM machines [5], or to establish the relative merits of counterpart PM motor topologies [6].…”

Section: Introductionmentioning

confidence: 99%

“…Depending on the particular application, the CE-FEA based design optimization techniques aim at realizing a set of objectives under certain performance constraints described/embedded in the optimization fitness function [2][3][4][5][6][7]. In line with the common practice, the CE-FEA based methods evaluate the associated fitness function at the rated load point, i.e.…”

Section: Introductionmentioning

confidence: 99%

Large-Scale Design Optimization of PM Machines Over a Target Operating Cycle

Nehl

et al. 2016

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A large-scale finite element(FE) model-based design optimization algorithm is developed for improving the drivecycle efficiency of permanent magnet (PM) synchronous machines with wide operating ranges such as those used in traction propulsion motors. The load operating cycle is efficiently modeled by using a systematic k-means clustering method to identify the operating points representing the high-energy-throughput zones in the torque-speed plane. The machine performance is evaluated over these cyclic representative points using a recently introduced computationally efficient-finite element analysis (CE-FEA) which is upgraded to include both constant torque and field weakening operations in the evaluation of the machine performance metrics. In contrast with the common practice, which aims at enhancing the rated performance, the entire range of operation is considered in the present design optimization method. Practical operational constraints imposed by the voltage and current limits of the motor-drive system, excessive PM demagnetization, and torque ripple are accounted for during the optimization process. The convergence to the optimal design solutions is expedited by utilizing a new stochastic optimizer. The developed design algorithm is applicable to any configuration of sinewave-drive PM and synchronous reluctance motors over any conceivable load profile. Its effectiveness is demonstrated by optimizing the well-established benchmark design represented by the Toyota Prius Gen. 2 interior PM motor configuration over a compound operating cycle consisting of common US driving schedules. Multiphysics electromagnetic, thermal and mechanical performance of the optimized design solutions is discussed in a post-design optimization stage.

“…Accordingly, design recommendations for mitigation of torque ripples, minimization of power losses, and reducing dependency on rare-earth PMs, have been often reported in the literature for naturally cooled (NC) machines. 9,10,11,16,17 Nevertheless, increasing the stator winding current density or the machine's ampere loading elevates the flux level and, hence, the saturation level throughout the machine's magnetic circuit. This not only affects the machine performance, but also alters the correlation between them and the geometric design parameters associated with the machine cross-section.…”

Section: Introductionmentioning

confidence: 99%

Optimal Design of IPM Motors With Different Cooling Systems and Winding Configurations

Ionel

et al. 2016

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Performance improvement of permanent magnet (PM) motors through optimization techniques has been widely investigated in the literature. Oftentimes the practice of design optimization leads to derivation/interpretation of optimal scaling rules of PM motors for a particular loading condition. This paper demonstrates how these derivations vary with respect to the machine ampere loading and ferrous core saturation level. A parallel sensitivity analysis using a second-order response surface methodology followed by a large-scale design optimization based on evolutionary algorithms are pursued in order to establish the variation of the relationships between the main design parameters and the performance characteristics with respect to the ampere loading and magnetic core saturation levels prevalent in the naturally cooled, fan-cooled, and liquid-cooled machines. For this purpose, a finite-element-based platform with a full account of complex geometry, magnetic core nonlinearities, and stator and rotor losses is used.Four main performance metrics including active material cost, power losses, torque ripple, and rotor PM demagnetization are investigated for two generic industrial PM motors with distributed and concentrated windings with subsequent conclusions drawn based on the results.