Winding Interior Permanent Magnet Research Articles

Design and Performance Comparison of Fractional Slot Concentrated Winding Spoke Type Synchronous Motors With Different Slot-Pole Combinations

Fractional slot concentrated winding (FSCW) interior permanent magnet (IPM) synchronous motors are nowadays an attractive solution in automotive applications due to their advantages in terms of high performance and manufacturing simplicity. Among the different topologies, the spoke type is an effective configuration when high torque density is required. On the other hand, the motor performance are heavily related to the selected slot-pole combination. This choice is critical in demanding automotive applications, such as electric power steering (EPS) systems, where high constraints in terms of torque density, torque quality, flux weakening performance, and noise/vibration/harshness are requested. This paper deals with the design and analysis of eight optimal slot/pole combinations FSCW IPM spoke type EPS motors. Two different low cost heavy rare earths free PM typologies, ferrite and hot-pressed NdFeB, are considered. A design and optimization procedure based upon the finite element analysis is presented. The impact of the magnetic properties and the slot/pole combination on the optimal motor dimensions, torque density, and motor cost is discussed. Cogging torque, torque ripple, electromechanical performance, and the stator deformation of the machines are evaluated, and the results are compared, highlighting the advantages and the differences among the solutions.

Experimental Verification of Rotor Demagnetization in a Fractional-Slot Concentrated-Winding PM Synchronous Machine Under Drive Fault Conditions

This paper presents the results of experimental tests designed to verify analytical predictions of the rotor demagnetization characteristics of a 0.6 kW (cont.) 9-slot/6-pole fractional-slot concentrated winding (FSCW) interior permanent magnet (IPM) synchronous machine. The demagnetization characteristics of the rotor magnets in this commercially produced FSCW-IPM machine are measured using a test configuration that is designed to conduct multiple demagnetization tests on the same test machine under controlled temperature conditions. In this paper, finite-element (FE) predictions of the rotor demagnetization characteristics of the experimental machine during three-phase symmetrical short-circuit and single-phase asymmetrical short-circuit faults are presented. These results are compared with experimental test measurements of the postfault currents and the magnet flux density distribution following demagnetization, demonstrating very good agreement of many key features. These comparisons also confirm that 3-D effects and magnet material properties such as the magnet thermal coefficients have a significant impact on some details of the FE predictions of the machine's fault-mode response characteristics.

Concentrated Winding IPM Synchronous Motor Design for Wide Field Weakening Applications

In order to understand the impact that certain design changes may have on the performance over a wide speed range, a series of 12-slot 8-pole concentrated winding interior permanent magnet synchronous motors (IPMSMs) are analyzed. Fundamental theory of operation is used to describe the desirable characteristics in terms of the lumped parameters, and finite element analysis is carried out to show how these characteristics may be realized through the motor geometry changes. The motor geometry changes aim to create an IPMSM design with high d -axis inductance for the wide speed range operation, low harmonic content in the back electromotive force waveform, and low cogging torque. A prototype is constructed and test results are presented for verification.

Stator Winding Interturn Short-Circuit Faults Severity Detection Controlled by OW-SVPWM Without CMV of a Five-Phase FTFSCW-IPM

This paper proposed a method to detect different interturn short-circuit fault severity by analyzing zero-sequence current for a new five-phase fault-tolerant fractional-slot concentrated winding interior permanent magnet motor (FTFSCW-IPM). To eliminate the effect of common-mode voltage in single dc power supply application, fault severity analysis is conducted based on an open-end winding (OW) space vector. This new method is verified by simulation and experimental results in a five-phase FTFSCW-IPM OW system.

Application of stator shifting to five‐phase fractional‐slot concentrated winding interior permanent magnet synchronous machine

In many applications, interior permanent magnet synchronous machines (IPMSMs) with fractional slot concentrated windings (FSCWs) are considered promising candidates in terms of higher power density and efficiency. In addition, employing a multiphase stator winding improves the drive train availability and increases reliability. This study investigates the effect of applying stator shifting to five-phase FSCW winding IPMSMs to suppress the effect of the slot harmonics by doubling the number of slots. In this case, the winding coil pitch will be two, which stands as a compromise between single-tooth and distributed winding topologies. This highly improves the air gap flux distribution, significantly reduces both rotor core and magnet eddy current losses, and increases saliency ratio and reluctance torque component. Moreover, an improved performance under fault conditions, in terms of lower torque ripple, and core and magnet losses, adds to the main advantages of this technique. Various slot/pole combinations suitable for five-phase machines are investigated. A full simulation case study based on two-dimensional finite element analysis is applied to the 20-slot/18-pole stator with single-tooth winding under both healthy and open-circuit phase fault cases.

Increasing the saliency ratio of fractional slot concentrated winding interior permanent magnet synchronous motors

In permanent magnet synchronous motor (PMSM) servo systems, the saliency ratio is an important factor in sensorless control and flux-weakening control. Compared with the interior PMSM (IPMSM) with distributed windings, the IPMSM with concentrated windings gains more popularity in servo system applications. However, the saliency ratio of current fractional slot concentrated windings (FSCWs) IPMSM is low and hard to increase, without much literature investigating how to improve the ratio. In this paper, the components of d - and q -axes inductances of FSCW IPMSM are determined, a novel concept named mechanical phase region is introduced and the key parameters influencing the saliency ratio of FSCW PMSMs have been investigated through thorough theoretical analysis and simulation. The design principles on increasing the saliency ratio of FSCW IPMSMs are proposed and the maximum saliency ratio of a 10 poles 12 slots motor is obtained. On the basis of the theory, a novel rotor structure with higher saliency ratio is designed. A new experimental method of measuring d - and q -axes inductances closes this paper with three experimental prototypes built to verify the theory and simulation results.

Basic Study on Loss Factor Evaluation of Concentrated Winding Permanent Magnet Synchronous Motor

SUMMARYThis paper describes the influence of pulse width modulation (PWM) inverter harmonic loss on concentrated winding interior permanent magnet synchronous motor characteristics by using finite element method (FEM) analysis and several measurements. In the measurements, the PWM inverter harmonic loss was evaluated by using a PWM inverter and a sinusoidal power supply. By using the FEM analysis, it was confirmed that the PWM inverter harmonic mainly caused an increase of eddy current losses in the magnetic steel sheet and the permanent magnet. The results indicate that higher inductance of the motor is effective in reducing the harmful effects of PWM inverter harmonics.

Evolutionary Optimization of a Fractional Slot Interior Permanent Magnet Motor for a Small Electric Bus

Fractional Slot Concentrated Winding (FSCW) Interior Permanent Magnet (IPM) motors constitute a favorable choice for electric vehicle applications due to their inherent advantages of high efficiency and performance, field weakening capability and permanent magnet effective shielding from eddy currents. In this paper, an IPM motor with buried sinusoidal magnets for a small electric bus is optimized in terms of both efficiency and performance. The overall magnet volume and the corresponding iron bridge width are maintained within specified borders, thus enabling adequate field weakening and permanent magnet shielding margins. In the optimization process a single-objective Differential Evolution (DE) algorithm is utilized, showing great convergence characteristics.

Torque Density Elevation in Concentrated Winding Interior PM Synchronous Motor With Minimized Magnet Volume

Permanent magnet (PM) synchronous motors (PMSMs) have been used to drive a number of vehicles. They have high torque density, high efficiency, and a wide speed range. However, the high cost of PMs is disadvantageous. This paper presents a technique for increasing the torque density by modifying the shape of the PMs and minimizing the magnet volume. The PM characteristics such as flux density, demagnetizing force, PM energy product, and the air-gap flux density are represented by a lumped magnetic equivalent circuit when the thickness and width of the PM are increased for the same volume but with different shapes. The torque, torque ripple, core loss, magnet loss, and efficiency of three interior (IPMSM) models designed by the proposed method are compared by finite element analysis. In addition, the demagnetization of the PM due to high temperature, maximum torque load angle, and an adverse field is analyzed. Finally, the analysis result is compared with that of the experiment to verify the proposed model.

Design and Experimental Verification of an 18-Slot/14-pole Fractional-Slot Concentrated Winding Interior Permanent Magnet Machine

This paper presents the design and the experimental verification of an 18-slot/14-pole fractional-slot concentrated winding interior permanent magnet machine. The prototype machine was optimized for wide constant power speed range (7:1) and very low cogging torque, two of the most important requirements for traction machines. Measured performance of the constructed prototype machine has confirmed the finite-element modeling results. Experience gained from this study has led to develop a set of design rules for the concentrated winding (CW)- interior permanent magnet (IPM) machine. Scaling up of the prototype design based on these rules is also discussed in this paper.

Flux‐weakening operation of open‐end winding drive integrating a cost‐effective high‐power charger

In this study, a three-phase drive with a six-leg voltage source inverter and an open-end winding interior permanent magnet synchronous machine designed for traction of an electric vehicle is studied in a flux-weakening operation. The topology allows the functionality of a high-power charger to be obtained, without adding any other supplementary power devices. On the other hand, since there are three independent currents, the control structure has to handle not only the two dq-current components but also a zero-sequence current. If neglected, in comparison with a wye-coupled three-phase drive, this zero-sequence component can cause a higher maximum peak value of the phase currents, additional stator Joule losses, torque ripple, inverter voltage saturation and insulated gate bipolar transistor (IGBT) oversizing. The proposed control strategy consists in adapting a conventional method used for wye-connected machines particularly in flux-weakening operation. This strategy allows the closed-loop control of the zero-sequence current to be maintained in the whole speed range and therefore inverter saturation is avoided. Simulations and experimental results are presented and analysed.

Basic Study on Loss Factor Evaluation of Concentrated Winding Permanent Magnet Synchronous Motor

SUMMARY This paper describes the influence of pulse width modulation (PWM) inverter harmonic loss on concentrated winding interior permanent magnet synchronous motor characteristics by using finite element method (FEM) analysis and several measurements. In the measurements, the PWM inverter harmonic loss was evaluated by using a PWM inverter and a sinusoidal power supply. By using the FEM analysis, it was confirmed that the PWM inverter harmonic mainly caused an increase of eddy current losses in the magnetic steel sheet and the permanent magnet. The results indicate that higher inductance of the motor is effective in reducing the harmful effects of PWM inverter harmonics.

高保磁力磁石を用いたＨＥＶ車用モータの小形化の検討

The distributed winding interior permanent magnet (IPM) motor is generally used for the traction drive of hybrid electric vehicle because it assumes wide torque-speed range. However, they have a big winding-overhang producing unnecessary copper-losses and extending the stator axial length. That reduces the torque density and increases the costs. The solution is using of concentrated windings. This solution makes it can significantly reduce (roughly 50 %) the winding-overhang. The increase of torque density is limited by permanent magnet demagnetization at high-current operation. To solve the problem, the high coercivity magnet is necessary, preventing the motor from demagnetizing. This paper examines the feasibility study of increasing torque density to the concentrated winding IPM motor with using of high coercivity magnet(2387 kA/m, 30 kOe). The results I got is the torque density can be increased 25 % compared to the conventional distributed winding motor, which realizes 25% downsizing of the motor.