This article presents the simultaneous magnetic and structural topology optimization of a transverse laminated synchronous reluctance machine rotor using a solid isotropic with material penalization ...(SIMP)-based approach with the globally convergent method of moving asymptotes (GCMMA) optimization algorithm. Magneto-structural single and multi-objective optimization formulations are presented. The single objective formulation maximizes the average torque subject to constraints on torque ripple, Von Mises stress, and compliance. The multiobjective formulation simultaneously maximizes average torque and minimizes compliance subject to constraints on torque ripple and Von Mises stress. In both optimization formulations, the electrical steel densities in the rotor mesh elements are the control variables. Including stress and compliance in the optimization formulation ensures a structurally feasible design. The design-dependent centripetal force contributed by each element in the rotor mesh is considered dependent on its density and mass. An intermediate density material issue is observed where the density of the material in a mesh element does not converge fully to air or electrical steel. This issue is addressed through the use of a thresholding mass function which forces the convergence of the mass but not the density. The two optimization formulations are compared for rotors operating at 4000 and 12 000 r/min. An initial magnetic only topology optimization is used to seed the magneto-structural topology optimization to decrease the computational time. The impact of the magnetic only seed and rotor mesh density on the optimization outcomes is also examined.
A magneto-structural combined dimensional and topology optimization approach for interior permanent magnet synchronous machine (IPMSM) rotor design is proposed using the solid isotropic material with ...penalization (SIMP) density-based topology optimization method. This method optimizes the location and dimensions of the permanent magnets (PMs) embedded in the rotor, while simultaneously optimizing the lamination flux barriers using topology optimization. To allow for the location and dimensions of the PMs to change a Laplace smoothing mesh deformation technique is used. Three examples of IPMSM rotor optimizations are presented to demonstrate the proposed approach. In addition, a geometric template-based optimization is carried out for a comparison to one of the dimensional and topology optimized examples to better illustrate the difference.
This paper presents a magneto-structural combined dimensional and topology optimization technique for interior permanent magnet synchronous machine (IPMSM) and wound field synchronous machine (WFSM) ...rotors. Dimensional changes to the permanent magnet (PM) and rotor winding location or size are accomplished by interpolating or projecting a smoothed Heaviside rectangular function representing the presence of PM material onto the IPMSM rotor design domain mesh, whereas the presence of copper material for WFSM rotor is interpolated in the same manner. A density based Solid Isotropic Material with Penalization (SIMP) topology optimization approach is then used to vary the presence of electrical steel in mesh elements to form flux barriers around the PM. The proposed method enforces a defined shape for the PM without requiring the mesh in the design domain to be deformed. Four examples are presented to demonstrate the technique: two flat bar IPMSM, one V-shaped IPMSM and a WFSM. A comparative study is performed on one of the flat bar IPMSMs using Metamodel of Optimal Prognosis (MOP) based method.
As a metric for measuring the combined space harmonic content of electric machine winding magnetomotive force (MMF), the winding total harmonic distortion (THD) is defined with an infinite series. ...Without truncation, the exact THD can be evaluated via a "family grouping" facilitated by a "family sum" over the fewest possible winding factors. Uniformly applicable to distributed windings and fractional-slot concentrated windings (FSCWs), this procedure also explains the inherent difference in harmonic content between both winding categories. Furthermore, the minimal THD (mTHD) that can be achieved by optimizing a winding is revealed with a closed-form expression. While intended for windings, the mTHD concept also benefits the design of low harmonic content rotor magnetic fields. Examples of both winding and rotor mTHD designs are provided.
Wound field synchronous generators (WFSG) are the standard electromechanical converter for back-up and utility scale power generation. Maintenance costs may be minimized by adopting noncontact or ..."brushless" technologies to replace sliding slip ring connections for rotor field excitation. This paper presents a brushless excitation approach using ceramic insulated sleeve (journal) bearings with oil lubrication to form capacitively coupled slip rings, in contrast to more traditional inductive brushless exciters and rotary transformers. This capacitive power transfer (CPT) approach exhibits advantages including low weight, low volume, and has a relatively simple construction using off-the-shelf components. Analysis, design, and prototype construction of the CPT system are presented. Experimental results demonstrate that 1.7 nF of capacitive coupling transfers 340 W to the rotor field winding of a 10 kW 208 V WFSG. Voltage regulation of a WFSG is demonstrated during steady state and 1 per unit load step changes yielding a NEMA-MG1 class G2 rating.
This paper studies the design of electric machine windings with reduced magnetomotive force (MMF) space harmonic content by adjusting the slot distribution and coil turns. Closed-form expressions for ...the winding factor and harmonic magnitudes established from a mathematical representation of winding functions are used to formulate the MMF space harmonic suppression problem. The framework is applicable to both distributed windings and fractional-slot concentrated windings (FSCWs) and can be solved with different techniques. No special requirements on the slot/pole combination and the number of layers are necessary. One example uses a linear algebraic technique to solve simultaneous equations and the result is a mixed-layer distributed winding. The process also reveals the criterion when multiple requirements on the winding factor and harmonic magnitudes can be satisfied concurrently. Contour plots are included to provide additional graphical insight. Another example designs a 24-slot 22-pole FSCW subset with numerical optimization. The resultant winding is a four-layer FSCW with two subsets and 3/4 of the harmonic orders are eliminated. The performance improvement of this winding is verified with finite-element simulations.
With rapid electrification of transportation, it is becoming increasingly important to have a comprehensive understanding of criteria used in motor selection. This paper presents the design and ...comparative evaluation for an interior permanent magnet synchronous motor (IPMSM) with distributed winding and concentrated winding, induction motor (IM), and switched reluctance motor (SRM) for an electric vehicle (EV) or hybrid electric vehicle (HEV) application. A fast finite element analysis (FEA) modeling approach is addressed for IM design. To account for highly nonlinear motor parameters and achieve high motor efficiency, optimal current trajectories are obtained by extensive mapping for IPMSMs and IM. Optimal turn-ON and turn-OFF angles with current chopping control and angular position control are found for SRM. Additional comparison including noise vibration and harshness (NVH) is also highlighted. Simulation and analytical results show that each motor topology demonstrates its own unique characteristic for EVs/HEVs. Each motor's highest efficiency region is located at different torque-speed regions for the criteria defined. Stator geometry, pole/slot combination, and control strategy differentiate NVH performance.
Three multi-carboxylic acid functionalised ligands have been designed, synthesised and utilised to prepare the new barium-based MOFs, MFM-510, -511, and -512, which show excellent stability to ...water-vapour. MFM-510 and MFM-511 show moderate proton conductivities (2.1 × 10
and 5.1 × 10
S cm
, respectively) at 99% RH and 298 K, attributed to the lack of free protons or hindered proton diffusion within the framework structures. In contrast, MFM-512, which incorporates a pendant carboxylic acid group directed into the pore of the framework, shows a two orders of magnitude enhancement in proton conductivity (2.9 × 10
S cm
). Quasi-elastic neutron scattering (QENS) suggests that the proton dynamics of MFM-512 are mediated by "free diffusion inside a sphere" confirming that incorporation of free carboxylic acid groups within the pores of MOFs is an efficient albeit synthetically challenging strategy to improve proton conductivity.
Research into electric machine windings with reduced magnetomotive force (MMF) space harmonic content has a long history. However, attention has often been confined to lower order harmonics with ...larger magnitudes. To more clearly and easily visualize the MMF space harmonic spectrum, this paper will explain the phenomenon of harmonic "families" intrinsic to a majority of electric machine windings. With a concise proof, it will be shown that within each family, the harmonic components have magnitudes that are inversely proportional to their orders. As a consequence, harmonics of the same family have the same winding factor. The number of families and, hence, different winding factors is found to be only a fraction of the number of slots of a unit machine. The family phenomenon greatly simplifies the determination of an MMF harmonic spectrum, envisions the behavior of higher order components, and predicts how a design change can improve the winding harmonic profile. When the family phenomenon disappears and the special cases with enlarged periods are also discussed. Two examples, both eliminating the 5th- and 7th-order harmonics but with very different harmonic spectra, are analyzed and compared to illustrate the power of the family phenomenon to aid the design of windings with improved electromagnetic performance.
A combined magneto-structural topology optimization approach based on the solid isotropic with material penalization method is proposed for wound field synchronous machines (WFSMs) to optimally ...distribute multiple materials including electrical steel, copper, and air in a rotor design domain. Magnetic topology optimization is simultaneously combined with structural topology optimization to ensure rotors, which are mechanically feasible. A topology optimization approach does not require the use of a geometric template where dimensions are controlled by parameters. Example designs of salient pole WFSM rotors are used to demonstrate the proposed technique. The proposed topology optimization technique is compared with a multiobjective optimization with the rotor geometry defined by a geometric template. For the same torque level the topology optimized rotor has lower copper losses.
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