Design Of Synchronous Machine Research Articles

Design and finite element analysis of a hybrid excitation synchronous machine

The paper presents a hybrid excited synchronous generator(HESG) with field windings and permanent magnets. This paper focuses on the analysis in the operating principle, rotor shape optimization, and inductance characteristic, based on finite element method. The measured voltage waveforms suggest that the rotor shape optimization in the study is a feasible solution to improve the quality of output voltage. Both the simulation and the tested results on generator performance verify further that the electric excitation can efficiently adjust the air-gap flux. Compared to conventional electric excited synchronous generator, the load capacity is improved due to relatively low armature inductance of the HESG.

Space Harmonics of Synchronous Machines Calculated by Finite Element Method

Space harmonics of synchronous machines are investigated in this paper through a specially designed synchronous machine. A 2-D finite-element method is used to calculate the magnetic field of the machine. The space harmonic magnitude and phase angle can be computed based on the magnetic flux density. The machine is specially designed and can be excited from the direct axis, quadrature axis, and various intermediate axes. The overall finite-element calculation accuracy is validated by the measured open-circuit characteristic curves. The space harmonic investigation in this paper provides valuable insight of the space harmonic contents of synchronous machines, which can help to develop a more advanced harmonic prediction method for the synchronous machine's design and operation.

Design of dual winding permanent magnet synchronous machines for hybrid electric vehicle accessory drives

This paper presents a new accessory drive system for hybrid electric vehicles (HEVs). This new concept involves a dual winding electric machine with simultaneous motor and generator functions. The electric machine provides power for all accessory loads such as the steering pump, compressors and 12 V loads. When the engine is off, the electric machine starts its motoring action and provides mechanical power to the accessory loads. Simultaneously, the generator windings provide power for the 12 V loads. The proposed structure could be a viable choice for fault-tolerant applications because of the concentrated winding type that maintains electrical and magnetic isolation. Design considerations of the proposed electric machine are outlined in the paper. The distributed winding topology and concentrated winding topologies are also compared. Analytical proof of magnetic decoupling is presented and experimentally verified.

Electromagnetic performance analysis of multilayer interior PMSM with fractional slot concentrated windings for electric vehicle applications

This paper presents the design and analysis of fractional slot multilayer interior permanent magnet synchronous machines (PMSMs) with concentrated winding for electric vehicles applications. The major advantages of concentrated winding will be analyzed first. The significant design consideration of multilayer interior permanent magnet machines will be illustrated, as well. Finally, the advanced finite element method will be employed to verify the detailed electromagnetic performance of the proposed interior PMSMs.

Effects of Imperfect Manufacturing Process on Electromagnetic Performances and Online Inter-turn Fault Detection in PMSMs

This paper deals with the consequences of some manufacturing imprecision related to the use of a fractional-slot concentrated winding (FSCW) in recent permanent-magnet synchronous machine (PMSM) designs. Although these topologies improve the efficiency of motors, they also lead to consider complex models, including undesirable harmonics, which can be strongly different from classical models expressed in a rotating frame. This may affect the control and the monitoring techniques used to detect some commonly reported faults such as turn short-circuit faults in the windings. Thus, adaptations are needed to improve classical fault detection methods. This paper considers an undesirable additional air gap, due to an imperfect manufacturing process, between the stator back iron and the teeth of a modular PMSM having an FSCW. A finite-element method and permeance network modeling are used to study the behavior of the machine. Good agreement is obtained between the two methods, validating the significant effects of such manufacturing faults on the behavior of the machine. Experimental tests confirm the occurrence of additional air gaps and their consequences on some classical interturn fault detection methods. Improvements are also proposed in order to consider relevant indicators even in the presence of inherent manufacturing faults.

Transient Response Enhancement of High Order Synchronous Machine based on Evolutionary PID controller

An efficient controller based on joint between original proportional-integral-derivative (PID) controller and fast genetic algorithm (FGA) is proposed to enhance the transient response of high order synchronous machine. PID controller has several advantages in practical design of synchronous machine compared with another controller。The transient response parameters with PID controller of synchronous machine are reasonable, but they susceptible to the local minima problem and not adequate. Therefore, FGA is used to overcome this problem and to enhance the transient response. Performance of the proposed controller is tested through a high order synchronous machine model and then compared with the original PID controller. In this paper the weak coupling relationship between the automatic voltage controller (AVR) and automatic generation control (AGC) in the synchronous machine has been proved to simplify the overall model. The results demonstrate that, the proposed controller is an efficiency and better than a conventional PID controller.

Linear synchronous electromagnetic machines for low-frequency impact technologies

The trend is considered toward development and application of various linear electromagnetic impact machine designs wherein the reciprocal motion of the plunger (armature) is timed with the frequency of the voltage pulses fed to the motor winding (coil) or a system of such coils from a mains-frequency power source. Based on the differences found between the methods of regulating the forced mechanical vibration regimes of the plunger, an analysis is made of the advantages and shortcomings of the operating cycles of synchronous machines built mainly around single- and double-coil designs. Novel electromagnetic synchronous machine designs are presented, along with their operating cycle control methods providing for a necessary sequence of alternation of the voltage half-waves applied to the coils, which make it possible to reduce the current pulse amplitude and the effect of the operation of the impact-type electric drive on the supply circuit. New technical solutions are suggested for improvement of the adjustment accuracy and stability of the forced vibration regime, which improves the performance characteristics and operating conditions of machines.

Optimal design of synchronous reluctance machine

Purpose – The purpose of this paper is to present optimally designed synchronous reluctance machine (SynRM) to demonstrate the feasibility of eliminating the use of rare earth permanent magnet (PM) in electric machine for vehicle traction applications. Design/methodology/approach – A typical rare earth interior permanent magnet (IPM) machine is used as the benchmark to conduct the optimal design study. Based on the flux distribution, major changes are made to the rotor lamination design. Enhanced torque production and lower torque ripple are specifically targeted as the two main objectives of the proposed design approach. Findings – As a result, the optimally designed SynRM can achieve performance very close to that of the benchmark PM machine with a potential for further improvement. Originality/value – Discussions of IPM replacement by optimally designed SynRM in electrical and hybrid electrical vehicles are given in terms of performance and cost.

Design and Control of IPMSM Sensorless Drive for Mechanical Rotor Position Estimation Capability

In this paper, a design and control method of interior permanent magnet synchronous machines (IPMSMs), which is controlled in sensorless position control mode based on high frequency signal injection, for absolute position estimation and control capability has been addressed. Although conventional motor designs with symmetric structure work well in sensorless speed and torque control modes, their actual mechanical rotor position is unidentifiable since their inductance profile is repeated for every electrical revolution. To realize the mechanical rotor position estimation capability, from a given template six-pole/nine-slot IPMSM with symmetric structure, an IPMSM design with asymmetric winding and asymmetric rotor geometry is proposed and constructed as a prototype. Based on the proposed design, the mechanical rotor position can be identified at the cost of slight degradation of basic motor characteristics such as torque ripples, harmonics in back EMF, and so on. The overall performances of the proposed IPMSM have been evaluated by rigorous finite element method simulations and experiments.

Design of Ferrite-Assisted Synchronous Reluctance Machines Robust Toward Demagnetization

The design of ferrite-assisted synchronous reluctance machines is investigated, with particular attention to the pivotal aspect of avoiding irreversible demagnetization. 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 is dependent on the operating temperature and the machine size. Furthermore, the comparison between the continuous load and demagnetization conditions shows that small- and medium-sized 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 12-pole direct-drive machine, rated 910 N · m at 200 r/min.

Parameter Estimation for Condition Monitoring of PMSM Stator Winding and Rotor Permanent Magnets

Winding resistance and rotor flux linkage are important to controller design and condition monitoring of a surface-mounted permanent-magnet synchronous machine (PMSM) system. In this paper, an online method for simultaneously estimating the winding resistance and rotor flux linkage of a PMSM is proposed, which is suitable for application under constant load torque. It is based on a proposed full-rank reference/variable model. Under constant load torque, a short pulse of id ≠ 0 is transiently injected into the d-axis current, and two sets of machine rotor speeds, currents, and voltages corresponding to id = 0 and id ≠ 0 are then measured for estimation. Since the torque is kept almost constant during the transient injection, owing to the moment of system inertia and negligible reluctance torque, the variation of rotor flux linkage due to injected id ≠ 0 can be taken into account by using the equation of constant torque without measuring the load torque and is then associated with the two sets of machine equations for simultaneously estimating the winding resistance and rotor flux linkage. Furthermore, the proposed method does not need the values of the dq-axis inductances, while the influence from the nonideal voltage measurement, which will cause an ill-conditioned problem in the estimation, has been taken into account and solved by error analysis. This method is finally verified on two prototype PMSMs and shows good performance.

Topology Optimization of a High-Temperature Superconducting Field Winding of a Synchronous Machine

This paper presents topology optimization (TO) of the high-temperature superconductor (HTS) field winding of an HTS synchronous machine. The TO problem is defined in order to find the minimum HTS material usage for a given HTS synchronous machine design. Optimization is performed using a modified genetic algorithm with local optimization search based on on/off sensitivity analysis. The results show an optimal HTS coil distribution, achieving compact designs with a maximum of approximately 22% of the available space for the field winding occupied with HTS tape. In addition, this paper describes potential HTS savings, which could be achieved using multiple power supplies for the excitation of the machine. Using the TO approach combined with two excitation currents, an additional HTS saving of 9.1% can be achieved.

Different Novel Electric Machine Designs for Automotive Applications

This paper presents three-different high efficiency and low costs electric machines types for automotive applications. For the PM machines with the single-layer concentrated windings, a novel stator topology with magnetic flux barriers in the stator teeth is used to increase the power density and the efficiency of the machine. Using this technique the material amount for the considered PM machine is reduced about 20% compared with the conventional design. For the asynchronous machines, two alternative solutions are presented; a new winding type with low space harmonic contents and also an ASM rotor with series connection of rotor bars solve the problem with high harmonics. Further, during the design of a new self-excited synchronous machine with concentrated winding, the high MMF winding harmonics are used to excite the rotor field winding.

An Approach to an Optimal Design of Permanent Magnet Synchronous Machines for Battery Electric Vehicles

The described design of a permanent magnet synchronous motor for battery electric vehicles is based on a drive cycle. For a given vehicle a set of operating points of the electric machine can be derived from the cycle. The next step in the design of the traction motor is to find a suitable lamination layout. Common motor design procedures take only a few representative operating points into account. This paper describes an approach which includes a large number of operating points at early stages of the motor design process. It is based on a specialized motor model and an optimization strategy which are described in this paper. As an example a traction motor for the VW Golf CityStromer is designed by using the proposed method.

Design of direct linear drives for manufacturing

The design of direct linear drives for manufacturing is considered. The benefits of synchronous machines with permanent-magnet excitation are outlined. The basic stages in the design of linear synchronous machines with permanent-magnet excitation are presented, and development results are discussed.

Effect of Radial Cooling Ducts on the Electromagnetic Performance of the Permanent Magnet Synchronous Generators With Double Radial Forced Air Cooling for Direct-Driven Wind Turbines

Most of the high-power, low-speed, direct-driven permanent magnet synchronous generators for wind energy applications apply a cooling solution where the stator core is divided into a number of substacks. Cooling air is blown through the stator through radial cooling channels formed between the adjacent stator substacks. The use of the stator substacks has an effect on the equivalent length of the generator, and thus, if neglected, leads to an incorrect no-load voltage and synchronous inductance calculation. In this paper, the design issues related to the thermal and electromagnetic design of permanent magnet synchronous machines are highlighted. The analysis starts with a preliminary electromagnetic design. Then, the allowable number and width of cooling ducts are calculated based on the maximum allowable temperatures and fluid flow speed with a thermal resistance network model. The effect of cooling ducts on the no-load voltage and synchronous inductances of the machine are discussed in detail. The calculated no-load voltage and synchronous inductances are used in the analytical performance evaluation. It is shown that the cross-saturation of the synchronous inductances must be taken into account in order to get realistic results.

Min-Max Univariate Dynamic Encoding Algorithm for Searches (uDEAS) and Its Application to Optimal Design of Electric Machines

Optimal design of Interior Permanent Magnet Synchronous Machines (IPMSM) is to obtain the global design optimum in association with the characteristic analysis investigating nonlinear magnetic saturation based on Finite Element Analysis (FEA). Since characteristic analysis occupies most part of the convergence time, the number of objective function must be called minimally. Hence, in this paper, MuDEAS is newly implemented in order to compensate the excessive computation time and the reliability of convergence to the global optimum. MuDEAS has been verified through a benchmark function and applied to the optimal design of IPMSM for maximizing Maximum Torque Per Ampere (MTPA) indentified with FEA.

Intelligent MADS With Clustering and Elastic Net and Its Application to Optimal Design of Interior PM Synchronous Machines

Optimal design of the electric machines is interlinked with the optimization algorithm for obtaining the quantitative optimum and numerical analysis of electric machines for the objective function. The optimization algorithm is required to evaluate the objective function minimal times since numerical analysis of the electric machines consumes a lot of time. In this paper, intelligent MADS with a clustering and elastic net is newly adopted for the optimal design of electric machines to raise the reliability of the global optimization and fast convergence time. In particular, the proposed algorithm is employed to the optimal design of the interior permanent-magnet PM synchronous machine minimizing torque ripples, which has been regarded as one of the complicated design problems.

Thrust Optimization of a Flux-Switching Linear Synchronous Machine With Yokeless Translator

Linear permanent magnet machines have been increasingly used in several applications that require high reliability and good dynamic characteristics. In this paper, a novel double-sided design of a 3φ permanent magnet flux-switching linear synchronous machine (FSLSM) with a yokeless translator is proposed. It is found that the proposed design can achieve more than 50% higher thrust than a conventional FSLSM and excellent linearity even under high excitation currents. Optimization of the proposed machine is performed using individual parameter optimization and is compared with results from global optimization using genetic algorithm (GA). Force analysis of the proposed design is performed to establish the mechanical integrity of the design. The proposed FSLSM is most suitable for long-stroke applications and intermittent oscillatory type applications.

Analytical prediction of cogging torque in surface mounted permanent magnet motors

The contribution of this paper is to provide a simple but quite rigorous analytical method for computing the cogging torque in surface mounted permanent magnet synchronous machines. It relies on the fact that the magnetic energy variation due to the presence of a slot on the stator side of the airgap can be expressed on the basis of the airgap field the magnets should produce on the stator side of the airgap in absence of slotting, simply by taking the square of the value of this field at the position corresponding to the center of the slot and multiplying it by a coefficient k0 which depends on the square of the slot opening. The cogging torque formula which can be deduced from this expression of the energy variation due to a slot is simple and well suited for inclusion in an optimization process aiming at the minimization of this torque during the design of SMPM synchronous machines with equal tooth widths as well as of machines with unequal tooth widths.