Optimal design of switched reluctance motors

The fundamental theory of the switched reluctance motor is presented with a number of new equations. It is used to show how the practical development of a design calculation should proceed, and this leads to a discussion of physical characteristics required to achieve satisfactory performance and to reduce acoustic noise. The paper makes a few generic observations on the characteristics of successful products that use switched reluctance motors. It is written at a basic engineering level and makes no attempt to apply sophisticated optimization theory

Embedded finite-element solver for computation of brushless permanent-magnet motors

This paper describes the theory underlying the formulation of a “minimum set” of finite-element solutions to be used in the design and analysis of saturated brushless permanent-magnet motors. The choice of finite-element solutions is described in terms of key points on the flux–MMF diagram. When the diagram has a regular shape, a huge reduction in finite-element analysis is possible with no loss of accuracy. If the loop is irregular, many more solutions are needed. This paper describes an efficient technique in which a finite-element solver is associated with a classical $d$– $q$-axis circuit model in such a way that the number of finite-element solutions in one electrical half-cycle can be varied between 1 and 360. The finite-element process is used to determine not only the average torque but also the saturated inductances as the rotor rotates

Design of Ferrite Assisted Synchronous Reluctance machines robust towards demagnetization

The design of ferrite-assisted synchronous reluctance machines is investigated, with particular attention to the pivotal aspect of avoiding irreversible de-magnetization. Geometric rules for obtaining a robust design are proposed and described analytically. The safe operating area is quantified in terms of the corresponding maximum electrical loading. Such demagnetization limit shows to be depending on the operating temperature and the machine size. Furthermore, the comparison between the continuous load and de-magnetization conditions shows that low and medium size machines can be stiffer against demagnetization, with respect to larger machines, and have room for transient overload. The analysis is validated by finite-elements and a design example is given, namely a twelve poles direct-drive machine, rated 910 Nm, 200 rpm

Design and Development of High Torque, Compact and Energy Saver PMSM Motor for Hydraulic Applications

The Permanent Magnet Synchronous Motor (PMSM) is widely used for various applications. It is the highly efficient motor as there are no field copper losses. The electrical energy is supplied to the motor through generator and the generator size depends upon the motor output. The efficiency of motor is the factor which will affect the size of the generator. This paper contributes the research work for the design of 35 kW, 440 V, 1000 rpm, 8 pole Synchronous Motor with Interior mounted Permanent Magnets (IPMSM) for the Hydraulic application. The designed IPMSM motor has efficiency of 98 % and can be used in place of 3-phase Induction Motor for the hydraulic application. The simulation is done in Ansys RMxprt fulfilling the required characteristics of Hydraulic application

A Dual-Consequent-Pole Vernier Memory Machine

This paper proposes a novel dual-consequent-pole Vernier memory machine (DCP-VMM) featuring alternatively arranged NdFeB and low coercive-force (LCF) magnet poles on the rotating and stationary sides, respectively. Due to the presence of LCF magnets that can be repetitively magnetized or demagnetized via a simple current pulse, the extra-high torque density at low-speed, and excellent high-efficient high-speed flux-weakening performance can be simultaneously realized. The configuration and operating principle, as well as the design considerations of the proposed machine are introduced, respectively. The finite element method (FEM) coupled with a nonlinear analytical hysteresis model for LCF magnets is employed to investigate the electromagnetic performance of the machine, which verifies the effectiveness of machine design and the feasibility as a competent candidate for automotive applications

The Flux-MMF diagram technique and its applications in analysis and comparative evaluation of electrical machines

The thesis describes a new technique, called the flux-MMF diagram technique, for analysis and comparative evaluation of electrical machines. The technique has evolved from the principle of virtual work, and the -i diagram, used commonly in designing switched reluctance machines and relays. Several applications of this technique are demonstrated in the thesis, supported by experimental validation. These are, the prediction of electromagnetic and cogging torque ripple, modelling of the effect of skew on torque and torque ripple, modelling of the variation of torque constant due to saturation, and comparative evaluation of different types of electrical machines. The thesis shows that the technique can be applied successfully in analysis of a wide variety of electrical machines. These include conventional machines such as the DC commutator, PM brushless AC, Interior PM, and the synchronous reluctance machine; as well as non-conventional machines such as the switched reluctance, PM brushless DC, and the doubly-salient PM machine. The technique has been implemented in a finite-element software, with the help of a link program which links the FE software with the dimensioning or sizing software, such as PC-BDC, produced by the SPEED Laboratory. The link program serves as a vital means of shortening the time it takes to analyse a new design in an FE software, by several orders of magnitude. The thesis also describes a new brushless doubly-salient permanent-magnet machine, called the flux-reversal machine. The design and fabrication process, and the experimental results are presented for a prototype single-phase, high-speed flux-reversal generator. The performance analysis of the prototype based on the flux-MMF diagram technique is included, and this validates its capability in analysing new and non-conventional machines, which cannot be analysed using the classical means

Development and Analysis of Interior Permanent Magnet Synchronous Motor with Field Excitation Structure

Throughout the years Hybrid Electric Vehicles (HEV) require an electric motor which has high power density, high efficiency, and wide constant power operating region as well as low manufacturing cost. For these purposes, a new Interior Permanent Magnet Synchronous Motor (IPMSM) with brushless field excitation (BFE) is designed and analyzed. This unique BFE structure is devised to control the amount of the air-gap flux for the purpose of achieving higher torque by increasing the air-gap flux at low speed and wider operating speed range by weakening the flux at high speed. On the process of developing the new IPMSM, the following analysis results are presented. Firstly, a new analytical method of output torque calculations for IPMSM is shown. This method works well when using a 2-dimensional magnetic equivalent circuit of a machine by omitting the step of calculating the inductance values which are required for the calculation of the reluctance torque. Secondly, there is a research about the slanted air-gap shape. This structure is intended to maximize the ratio of the back-emf of a machine that is controllable by BFE as well as increase the output torque. The study of various slanted air-gap shapes suggests a new method to increase torque density of IPMSM. Lastly, the conventional two-axis IPMSM model is modified to include the cross saturation effect by adding the cross-coupled inductance terms for calculating the power factor and output torque in comparing different saturated conditions. The results suggest that the effect of cross-coupled inductance is increase when d-axis current is high on the negative direction

Design of High Efficiency Brushless Permanent Magnet Machines and Driver System

The dissertation is concerned with the design of high-efficiency permanent magnet synchronous machinery and the control system. The dissertation first talks about the basic concept of the permanent magnet synchronous motor (PMSM) design and the mathematics design model of the advanced design method. The advantage of the design method is that it can increase the high load capacity at no cost of increasing the total machine size. After that, the control method of the PMSM and Permanent magnet synchronous generator (PMSG) is introduced. The design, simulation, and test of a permanent magnet brushless DC (BLDC) motor for electric impact wrench and new mechanical structure are first presented based on the design method. Finite element analysis based on the Maxwell 2D is built to optimize the design and the control board is designed using Altium Designer. Both the motor and control board have been fabricated and tested to verify the design. The electrical and mechanical design are combined, and it provides an analytical IPMBLDC design method and an innovative and reasonable mechanical dynamical calculation method for the impact wrench system, which can be used in whole system design of other functional electric tools. A 2kw high-efficiency alternator system and its control board system are also designed, analyzed and fabricated applying to the truck auxiliary power unit (APU). The alternator system has two stages. The first stage is that the alternator three-phase outputs are connected to the three-phase active rectifier to get 48V DC. An advanced Sliding Mode Observer (SMO) is used to get an alternator position. The buck is used for the second stage to get 14V DC output. The whole system efficiency is much higher than the traditional system using induction motor

Torque Characterization of Permanent Magnet and Synchronous Reluctance Machines

The characterization of an electric machine can be evaluated using different available machine design and analysis softwares prior to manufacturing. These machine design softwares are either Finite Element Analysis (FEA) based or analytical model based. Each design software formulates and solves the machine design problem differently. Therefore, there is always a discrepancy in the results obtained from each of these softwares. The expertise of the user also affects the outcome of the analysis. Moreover, the desired performance of a machine is highly influenced by the manufacturing and assembly process of its various components. Hence, it is extremely important to characterize the design and performance of a special machine in different machine design softwares before and after fabrication. To validate the design methodologies, the accuracy of FEA softwares, machine models, as well as the manufacturing and assembly process, a comparative analysis should be performed between the results obtained from the software and experimental characterizations. In this thesis, the characterization of a variable-flux permanent magnet machine, synchronous reluctance machines (SynRMs), and a novel interior permanent magnet synchronous machine (PMSM) with improved torque utilization, is presented. Three different machine design softwares, namely MotorSolve, MagNet, and MagneForce are used to characterize the machines. This thesis initially presents the characterization of a 7.5 hp variable-flux permanent magnet machine. The back emf, magnet flux linkage, torque-angle, and core loss characterization is carried out for this machine. An error band is introduced for the experimental torque-angle curves. This error band contains the tolerance and resolution of the torque transducer and conditioner. Additionally, an analytical model is implemented to estimate the core losses in the prototyped variable-flux PM machine. The results obtained from software and experimental characterizations show an acceptable agreement. A comprehensive manufacturing and assembly process of the SynRMs for rapid prototyping is also presented in this thesis. The application of nonconventional photochemical machining process to produce the SynRM laminations is described. In addition, various stages of manufacturing, stator and rotor assembly techniques, rotor balancing procedure as well as specialized components used at various stages of the process are also presented. To validate the accuracy of the design and fabrication, the characterization of three SynRMs is then performed. This consists of static torque-angle characterization, inductance characterization, and dynamic characterization. An error band is also included for the experimental torque-angle curves. A regenerative dynamometer test system is developed to perform various static and dynamic characterizations. This test setup is equipped with a real-time supervisory controller as well as measurement and monitoring instruments. Finally, a novel interior PMSM topology with improved torque utilization to reduce magnet volume is characterized. The no-load back emf and static torque-angle are simulated and measured. A search coil based advance instrumentation system to monitor the machine’s parameters is discussed. The design, manufacturing, and implementation of the search coils to measure flux density in the stator of the novel interior PMSM are also discussed. For every characterization, a comparative analysis is performed to validate the design methodologies, accuracy of FEA softwares, machine models, manufacturing, and assembly process