This paper proposes the design optimization procedure of three-phase interior permanent magnet (IPM) synchronous motors with minimum weight, maximum power output, and suitability for wide constant-power region operation. The particular rotor geometry of the IPM synchronous motor and the presence of several variables and constraints make the design problem very complicated. The authors propose to combine an accurate finite-element analysis with a multiobjective optimization procedure using a new algorithm belonging to the class of controlled random search algorithms. The optimization procedure has been employed to design two IPM motors for industrial application and a city electrical scooter. A prototype has been realized and tested. The comparison between the predicted and measured performances shows the reliability of the simulation results and the effectiveness, versatility, and robustness of the proposed procedure.

Finite-Element-Based Multiobjective Design Optimization Procedure of Interior Permanent Magnet Synchronous Motors for Wide Constant-Power Region Operation

This paper focuses on the design and analysis of a novel material-efficient permanent-magnet (PM) shape for surface-mounted PM (SPM) motors used in automotive actuators. Most of such applications require smooth torque with minimum pulsation for an accurate position control. The proposed PM shape is designed to be sinusoidal and symmetrical in the axial direction for minimizing the amount of rare earth magnets as well as for providing balanced axial electromagnetic force, which turns out to obtain better sinusoidal electromotive force, less cogging torque, and, consequently, smooth electromagnetic torque. The contribution of the novel PM shape to motor characteristics is first estimated by 3-D finite-element method, and all of the simulation results are compared with those of SPM motors with two conventional arched PM shapes: one previously reported sinusoidal PM shape and one step skewed PM shape. Finally, some finite-element analysis results are confirmed by experimental results.

Material-Efficient Permanent-Magnet Shape for Torque Pulsation Minimization in SPM Motors for Automotive Applications

This paper proposes to apply optimal approaches to the design and control of a highly constrained electric machine. The developed approach is applied on a permanent-magnet integrated starter generator (ISG) but may be applied on any high-constrained electric machine. One of the main problems in the use of optimal approaches is the accuracy of the models used by the optimizer. In our approach, we propose to proceed in two steps. 1) Optimal design: the model is purely analytic, and some phenomena are neglected (cross saturation). Under these conditions, the electric machine design is optimal for a limited number of constraints. The design model uses a classic uncoupled d,q reluctant circuit model (with saturation taken into account). 2) Optimal control: once the machine is calculated, the design constraints are validated by a finite-element (FE) method. The FE method allows to use a more accurate model to compute optimal currents for the control on the whole torque-speed plane. In our case, we use FE results to model the cross-saturation phenomenon. The optimizer is common to both cases and is a classic commercial sequential quadratic programming algorithm. This model is validated by experimental results based on an ISG. This paper shows that optimal design and control allows for permanent-magnet machine, high flux-weakening mode, and high-efficiency operations even for a simple machine structure

Integrated Starter Generator: The Need for an Optimal Design and Control Approach. Application to a Permanent Magnet Machine

The model allows the ultrafast nonlinear simulation of the steady-state performance of synchronous machines and is particularly suitable for brushless motors with nonoverlapping windings having coils concentrated around the teeth. Finite-element analysis (FEA) is employed only for calculating the magnetic vector potential in the coils, and the motor performance is then estimated through analytical formulas. For the example interior-permanent-magnet motors presented, as little as one magnetostatic finite-element (FE) solution was used for the fundamental flux linkage and average torque computation. Two FE solutions were employed for the core flux density waveforms and power loss estimation. A minimum of three solutions is recommended for the torque ripple, back electromotive force, and induced voltage. A substantial reduction of one to two orders of magnitude was achieved for the solving time as compared with the detailed time-stepping FEA. The surrogate FE model can also be tuned for increased speed, comparable with that of magnetic equivalent circuit solvers. The general applicability of the model is discussed, and recommendations are provided. Successful validation was performed against the detailed FEA and experiments.

Finite-Element Surrogate Model for Electric Machines With Revolving Field—Application to IPM Motors

This paper proposes to apply optimal multiphysic models to the design of highly constrained electrical machines, such as interior permanent-magnet (IPM) machine intended for an automotive integrated starter generators. One of the main problems in the use of such optimal approaches remains the accuracy of the models used by the optimizer. In a recent study, we proposed a design model linked to three strong hypotheses: 1) Iron losses are calculated according to the flux density fundamental (sinusoidal approach); 2) flux densities are estimated with a saturated but decoupled d,q reluctant circuit model neglecting the cross saturation effect; and 3) thermal states are indirectly treated with a current density limit. This paper improves these models by using first the finite element method for the determination of flux and iron losses in the machine and then an equivalent thermal steady-state lumped-parameter network. These models are included in the optimization loop and so are evaluated at each iteration. The optimization method uses standard sequential quadratic programming algorithm and Sequential Simplex algorithm. A comparison between the design of an IPM machine with the previous model and the new one will be performed.

Combination of Finite-Element and Analytical Models in the Optimal Multidomain Design of Machines: Application to an Interior Permanent-Magnet Starter Generator

The hard competition on the automotive electric actuation market has prompted engineers to look for advanced electromagnetic design techniques for electric machines This paper presents therefore an overview offering at the same time solutions for several applications An advanced optimization design method includes three different approaches: sizing, shaping, and structural (topological) optimization The case studies consider interior permanent magnet synchronous motors (IPMSM) for automotive applications like steering, braking, and clutch/shift actuation systems The following are presented: 1) sizing (dimensioning) based on experience in comparison with (multi-objective) optimization design, 2) synthesis of the sinusoidal back-emf shape by a coupled finite-element (FE)-grid-search method, and 3) two novel rotor topologies for minimal cogging torque and maximal pole flux simultaneously obtained by a coupled finite-element (FE)-genetic algorithms method

Advanced Optimization Design Techniques for Automotive Interior Permanent Magnet Synchronous Machines

The present paper presents an overview of actual high performance electric drives for automotive applications. The field of applications spans a broad range from active steering, power steering, electromechanical brakes, clutch and shift actuators, suspension, damping and stabilization actuators, heating, ventilation, and air conditioning up to starter-generators and traction, including x-by-wire (e.g. steer-by-wire, brake-by-wire). Most of these applications require high performance motors with a high torque/volume (mass) ratio, low inertia, high dynamics, good field-weakening and high temperature standing capability. In the actual situation on the global automotive market the demands for the electric actuators become more stringent.

Automotive Electrical Actuation Technologies

Electric Actuation Technologies for Automotive Steering Systems

This paper presents a first topological optimization approach for a sinusoidal interior permanent magnet synchronous machine. A coupled nonlinear 2D FE-GA technique was used. The goal of the optimal design was the synthesis of a maximal sinusoidal back-EMF and simultaneously the minimization of the cogging torque. Two novel rotor topologies for minimal cogging torque and maximal, sinusoidal pole flux were already implemented in series production

Topology Optimization of an Interior Permanent Magnet Synchronous Machine Using a Coupled Finite Elements ! Genetic Algorithms Technique

The paper presents back-EMF synthesis (design) techniques for both -sinusoidal and trapezoidal -permanent magnet synchronous machines (PMSM) technologies. One of the major original contributions is the fact that the introduced synthesis methods are taking into account the simultaneous cogging torque minimization. In comparison with the known machines with surface permanent magnets (PM), distributed windings and skewing, the present paper considers only machines with interior PM, concentrated windings (tooth-wound machines) and without skewing, as robust, low-cost solutions for the industrial practice. Several machine topologies are presented in comparison for the sinusoidal and trapezoidal technologies. The synthesis process involves exclusively nonlinear finite elements (FE) calculations of the back-EMF shape and cogging torque. For each machine technology design solutions with optimal back-EMF and low cogging torque are offered. Experimental (measurements) results for the built prototypes are presented in detail.

D. Iles-Klumpner

Papers

Advanced Optimization Design Techniques for Automotive Interior Permanent Magnet Synchronous Machines

Automotive Electrical Actuation Technologies

Electric Actuation Technologies for Automotive Steering Systems

Topology Optimization of an Interior Permanent Magnet Synchronous Machine Using a Coupled Finite Elements ! Genetic Algorithms Technique

Back-EMF synthesis for sinusoidal and trapezoidal tooth-wound interior permanent magnet synchronous machines without skewing