Concentrated Winding Interior Permanent Magnet Research Articles

Anti-Demagnetization Analysis of Fractional Slot Concentrated Windings Interior Permanent Magnet Motor Considering Effect of Rotor Design Parameters

This work investigates the effect of design parameters of permanent magnets (PMs) and flux barriers (FBs) in the rotor on the anti-demagnetization ability (ADA) of fractional slot concentrated windings interior PM (IPM) motors for electric scooters. A 2.5 kW IPM motor (12 slots and 8 poles) is designed for a wide speed range, and its ADA associated with different PM and FB arrangements is studied under high temperature and high current density operations. The analysis shows the relationship between the ADA and characteristic current (<inline-formula> <tex-math notation="LaTeX">$I_{\mathrm {ch}}$ </tex-math></inline-formula>, defined as the ratio of PM flux linkage to <inline-formula> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula>-axis inductance). It is also found that proper designs of FBs can significantly improve the ADA of the IPM motor without much affecting <inline-formula> <tex-math notation="LaTeX">$I_{\mathrm {ch}}$ </tex-math></inline-formula>. Thus, the motor ADA and performance can be simultaneously improved. Finite element analysis is used for evaluation, and experiments are conducted to validate the analysis.

Shaping of the Air Gap in a V-Typed IPMSM for Compressed-Air System Applications

The shaping of the air gap of a V-typed fractional slot concentrated windings interior permanent magnet synchronous machines (IPMSMs) is investigated for compressed-air system (CAS) applications in this article. The harmonics of no-load air gap density, average torque, torque ripple, and iron losses are studied by the finite element analysis (FEA). The results show that the air gap shaping of the V-typed IPMSM can be effectively used to reduce the torque ripple and stator core loss. It is because the low-order harmonics of the air gap flux density can be reduced with a little decrease in the average torque. The proposed air gap shaping methods have the advantages of simple design and simple manufacture. A V-typed IPMSM with air gap shaping is prototyped to verify the correctness of the analysis results.

Torque Pulsation Reduction in Fractional-Slot Concentrated-Windings IPM Motors by Lowering Sub-Harmonics

This paper proposes a method to reduce the torque pulsation of the three-phase fractional-slot concentrated-winding (FSCW) interior permanent magnet (IPM) motor by lowering sub-harmonics. The key principle of this method is the selection of an optimized six-layer winding with different numbers of conductors. Firstly, the interaction of stator-rotor magnetomotive force (MMF) which contributes to the torque pulsation is analyzed. Additionally, the relationship between sub-harmonics (1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> sub-harmonic and 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> sub-harmonic) and torque pulsation orders is revealed. Then, different numbers of conductors are adopted in coils to eliminate the 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> sub-harmonic. Nevertheless, the 1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> sub-harmonic increases in the two-layer and four-layer windings. Therefore, the optimized six-layer winding is employed to suppress the 1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> sub-harmonic and ensure that the 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> sub-harmonic is zero. Besides, there are almost no other harmonics except the main harmonic and slot harmonics in the proposed IPM motor. Hence, the torque pulsation can be greatly reduced even under different current angles. Furthermore, the principle for torque pulsation reduction by lowering sub-harmonics is revealed. The effectiveness of the proposed method is verified through the comparisons with finite element analysis and experimental test.

Highly Demagnetization Performance IPMSM Under Hot Environments

This paper examines how changing the magnetic orientation of permanent magnets in concentrated winding interior permanent magnet synchronous motors (IPMSMs) affects their demagnetization resistance. We evaluated a prototype for demagnetization at 180 °C that consists of a 130° V-shaped rotor core in which parallelogram magnets with oblique orientation are arranged and confirmed by finite element analysis where the demagnetization resistance increases as magnetic field orientation angle $\alpha $ becomes larger. For demagnetization evaluation of the prototype, it is easier to change the rotor core shape of a two-pole test rotor of a multipole IPMSM than a multipole rotor, and the demagnetization evaluation is performed using a small number of magnets.

Design and Comparison of Three-Phase and Five-Phase FTFSCW-IPM Motor Open-End Winding Drive Systems for Electric Vehicles Applications

This paper proposes and compares two new fault-tolerant fractional-slot concentrated-winding interior permanent magnet (FTFSCW-IPM) motor open-end winding (OW) drive systems for electric vehicles. The proposed FTFSCW-IPM motors possess the merits of high efficiency, high power density, and strong fault-tolerant capacity. Also, to further improve the reliability of control system, an OW dual inverter drive system is adopted. Furthermore, to better and clearer illustrate the advantages and disadvantages of multiphase machine system, the comprehensive comparison of three-phase and five-phase FTFSCW-IPM motor OW drive systems is carried out from the perspective of motor design and control system. The topologies and the features of the proposed two FTFSCW-IPM motors are analyzed, and the static characteristics are investigated and compared by using the finite-element analysis (FEA). Then, the evaluation of their OW drive system performance is conducted and compared by the simulation based on the MATLAB/Simulink. Finally, the FEA and simulation results are validated by experiment on both prototypes.

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.

Torque Ripple Reduction of Saliency-Based Sensorless Drive Concentrated-Winding IPMSM Using Novel Flux Barrier

This paper presents a novel flux barrier design of a torque ripple reduction in a saliency-based sensorless drive concentrated-winding interior permanent magnet synchronous motor (IPMSM). The motor is designed for general-purpose sensorless industrial drives and to fulfill the torque ripple requirement with the required maximum torque under the sensorless drive. The designed rotor has a V-shape magnet, and a circular flux barrier at the rotor yoke in the center of N- and S-poles. A 45- $\hbox{N}\cdot \hbox{m} $ –5.5-kW IPMSM has been manufactured to check the design validity. The validity of the proposed design procedure and the expected drive characteristics are experimentally verified by using the prototype.

Effect of Number of Layers on Performance of Fractional-Slot Concentrated-Windings Interior Permanent Magnet Machines

Interior PM machines equipped with fractional-slot concentrated-windings are good candidates for high-speed traction applications. This is mainly due to the higher power density and efficiency that can be achieved. The main challenge with this type of machines is the high rotor losses at high speeds/frequencies. This paper will thoroughly investigate the effect of number of winding layers on the performance of this type of machines. It will be shown that by going to higher number of layers, there can be significant improvement in efficiency especially at high speeds mainly due to the reduction of the winding factor/magnitude of the most dominant stator mmf subharmonic component. It will also be shown that there is significant improvement in torque density. Even though there is reduction in the winding factor of the stator synchronous torque-producing mmf component, this is more than offset by increase in machine saliency and reluctance torque. The paper will provide general guidelines regarding the optimum slot/pole/phase combinations based on torque density and efficiency. Sample designs of various slot/pole combinations are used to quantify the benefit of going to higher number of layers in terms of torque density, efficiency, and torque ripple.

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.

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.

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.