Arash Hassanpour Isfahani

Multiobjective design optimization of air-core linear permanent-magnet synchronous motors for improved thrust and low magnet consumption

Although air-core linear permanent-magnet (PM) synchronous motors are widely used in precision applications because of their advantages such as fast dynamics, lack of detent force, and negligible iron loss, they basically suffer from low developed thrust, thrust ripple, and excessive use of permanent-magnet materials, all of which lead to undesirable performance and high production cost. In this paper, we analyze performance characteristics of an air-core linear PM synchronous motor by varying motor design parameters in a layer model and a d-q model of the machine. We propose a multiobjective design optimization to improve thrust, thrust ripple, and consumed magnet volume independently and simultaneously by defining a flexible objective function. A genetic algorithm is employed to search for optimal designs. The results confirm that desirable thrust mean and substantial reduction in magnet volume and thrust ripple can be achieved. We draw several design conclusions from the motor analysis and design optimization. Finally, we carry out a time-stepping finite-element analysis to evaluate the effectiveness of the machine models and the optimization method.

Design Optimization of a Low-Speed Single-Sided Linear Induction Motor for Improved Efficiency and Power Factor

Although linear electrical motors (LMs) are increasingly used in industry to develop linear motion, they suffer from two major drawbacks: low efficiency and low power factor. These drawbacks cause high energy consumption and a rise in input current, and occupy transmission line capacity. We present a multiobjective optimization method to improve both efficiency and power factor, simultaneously. Our method uses an analytical model of the machine to calculate the efficiency and power factor. It allows us to investigate the effects of various motor specifications on the efficiency and the power factor. Motor parameters and dimensions can then be optimized by using a genetic algorithm in an appropriate objective function. The results show an enhancement in motor performance. We have used 2-D and 3-D time-stepping finite-element methods to evaluate the analytical results. A comparison of results validates our optimization method.

Optimization of a Contactless Power Transfer System for Electric Vehicles

A contactless charging system based on a circular coil configuration is presented for electric vehicles. An analytical model of the charging system is derived and used to investigate the effect of system dimensions on the system mutual inductance. The efficiency of the system is then calculated and used as a criterion to optimize the dimensions of transmitter and receiver coils in an uncompensated system, as well as series and parallel compensated systems. As a result, several design rules are presented. Following these rules, it is shown that significant improvement in the system efficiency is achieved by optimizing the coil dimensions while the length and weight of coils are kept constant. The performances of the optimized systems are evaluated using the 3-D finite-element method (FEM) and experiments. The FEM and experimental results are in good agreement, confirming the validity of the analytical model and the optimization approach.

Effects of Magnetizing Inductance on Start-Up and Synchronization of Line-Start Permanent-Magnet Synchronous Motors

The capabilities of proper start-up and synchronization are important issues in the design of line-start permanent magnet synchronous motors. Failing in early start-up or in synchronization under certain conditions prevents the widespread use of these motors. In order to draw useful guidelines for the design of line-start permanent magnet synchronous motors, the contradictory effects of a large value of magnetizing inductance in improving early start-up and deteriorating synchronization of line-start permanent magnet synchronous motors are analyzed in this paper. The analysis is done through three different methods. First, the effect of magnetizing inductance on average and pulsating torques of the motors during asynchronous operation is investigated and the role of these torques in start-up and synchronization performances of the motors is discussed. A critical load is then determined in terms of motors parameters as a torque limit above which the motors cannot start. The effect of magnetizing inductance, magnet flux, and saliency on the critical load is also investigated. A dynamic d-q model of the motors is then implemented to support the discussions by analyzing two line start motors with different magnetizing inductances. Finite-element-based analyses are then carried out for both motors to consider motors parameters variation, skin effect, saturation, rotor asymmetry, and cross magnetization. A good agreement between the finite-element method and dynamic simulation results is evident. Finally, some design guidelines are proposed for the proper selection of the magnetizing inductance in motor designs for different applications.

Using Modular Poles for Shape Optimization of Flux Density Distribution in Permanent-Magnet Machines

A modular configuration for a type of permanent-magnet pole is proposed for use in permanent-magnet (PM) machines. The pole consists of three or more permanent-magnet pieces. The main objective of this configuration is to shape the air-gap flux density distribution produced by the pole. An optimization procedure based on an analytical model is then used to determine the optimal pole specifications. A finite-element method is finally carried out to evaluate the proposed configuration. Extensive investigations on a linear permanent-magnet motor demonstrate that the proposed configuration reduces flux density as well as back electromotive force harmonics. This pole configuration also results in more efficient use of PM materials.

Enhanced Modeling of Linear Permanent-Magnet Synchronous Motors

Modeling of air-gap flux density distribution produced by magnet poles is essential for analysis and design of linear permanent-magnet synchronous motors. This is usually done by time-consuming numerical methods which are difficult to be incorporated in iterative motor design procedures or by approximate models which lack desirable accuracy. This paper presents an alternative method to model the air-gap flux density distribution which is both accurate and simple enough to be integrated into iterative motor design procedures. It consists of the solution of an improved magnetic equivalent circuit and an air-gap flux density distribution function (FDDF). The end teeth effects and magnetic saturation of iron core can be taken into account in the modeling. Different motor characteristics are calculated by means of the proposed FDDF. The accuracy of the proposed method in modeling of the machines is verified by the finite-element method and its superiority over a recent method based on an extensive machine model is demonstrated

Optimal Design of a Direct-Drive Permanent Magnet Synchronous Generator for Small-Scale Wind Energy Conversion Systems

This paper presents an optimal design of a direct-drive permanent magnet synchronous generator for a smallscale wind energy conversion system. An analytical model of a small-scale grid-connected wind energy conversion system is presented, and the effects of generator design parameters on the payback period of the system are investigated. An optimization procedure based on genetic algorithm method is then employed to optimize four design parameters of the generator for use in a region with relatively low wind-speed. The aim of optimization is minimizing the payback period of the initial investment on wind energy conversion systems for residential applications. This makes the use of these systems more economical and appealing. Finite element method is employed to evaluate the performance of the optimized generator. The results obtained from finite element analysis are close to those achieved by analytical model.

An educational toolbox for performance analysis of line-start permanent magnet synchronous motors

This article presents the development of an education purpose toolbox for performance analysis of three‐phase line start permanent magnet synchronous motors. The motor state‐space equations are implemented in Simulink and an easy to use graphic user interface is designed. The starting performance of a typical motor is then simulated in different conditions as a case study. This toolbox provides a friendly and efficient environment for students to become familiar with the performance of this type of motor which is receiving increasing attention in the industry and academic. An experimental study is also carried out to validate the toolbox.

Transient Finite-Element Analysis of Short-Circuit Electromagnetic Forces in Isolated Phase Buses

Abstract Short-circuit electromagnetic forces have a vital role in the mechanical design of isolated phase buses. Electromagnetic forces in isolated phase buses under short-circuit conditions are analyzed in this article. These forces are calculated using the time-stepping finite-element method. The effects of system dimensions and material properties on the maximum value of forces and the time of its occurrence are investigated through extensive simulation. The concluding remarks are useful for the design and protection of the buses.

Finite Element Analysis and Experimental Implementation of the Cylindrical Permanent Magnet Electrodynamic Suspension System

Abstract In this article, the performances of two electrodynamic suspension systems with flat and cylindrical structures are investigated and compared. The first system consists of a permanent magnet block levitated over a moving flat conducting plate. The second system consists of a permanent magnet block levitated over a rotating cylindrical conducting shell. The influences of systems specifications on their performances are studied using the 2-D finite element method. The minimum radius in which the performances of both systems are close enough is determined and used for experimental implementation. Finally, the results of the finite element method are compared with results obtained by experiment. It shows the accuracy of the finite element method in the estimation of the lift and drag forces of an electrodynamic suspension system. This study helps to find a proper cylindrical electrodynamic suspension system instead of a flat one, which is more complicated for implementation.