Seung-Hee Chai

Design and Verification of 150-krpm PMSM Based on Experiment Results of Prototype

This paper proposes the design process of a 2.62-kW 150-krpm high-speed surface-mounted permanent-magnet synchronous motor. To meet the required specifications, the numbers of poles and slots were determined by considering the maximum speed and the rotary stability affected by the vibration of the rotor. In addition, this paper describes not only the appropriate material selection method but also the appropriate geometry design method based on analytic approaches. Furthermore, to precisely evaluate the bearing and windage losses at a high speed, a method that combines the finite-element method and the experiment results of the prototype was used. As a result, an improved motor was designed, which had higher maximum power and speed than the prototype and a lower mass moment of inertia. Finally, tests were conducted to verify the validity of the proposed design process and the effectiveness of the motor.

Hysteresis Torque Analysis of Permanent Magnet Motors Using Preisach Model

This paper deals with the computation of hysteresis torque in electric machines by means of the hysteresis Preisach model in finite element methods. In most cases, core loss is divided into hysteresis loss and eddy current loss. However, this component experiences mostly hysteresis loss at low speed. This hysteresis loss acts on the braking torque with cogging in the permanent magnet motor. In order to analyze the hysteresis torque, the Preisach hysteresis model is applied to the post-processor using the finite element method. In this method, computation errors can occur more than with the existing analysis method, but this method can compute hysteresis torque without complex nonlinear analysis. The hysteresis torque that is bearing friction is compared with test results. Both simulations and experiments are performed to verify the validity of the proposed method.

Plastic Injection Molded Rotor of Concentrated Flux-Type Ferrite Magnet Motor for Dual-Clutch Transmission

Motors for dual-clutch transmission (DCT) system are required to minimize its size because of limited space on transmission. Characteristics, low cost, and high productivity are essential to DCT motor for competitiveness of mass production. Hence, concentrated flux-type ferrite magnet motor is suggested to meet the needs of DCT motor. Because concentrated flux-type permanent magnet motor has a high torque density, it is possible for ferrite magnet motor to achieve air-gap flux as high as a rare-earth magnet motor. The most important thing for the design of concentrated flux-type motor is to reduce the flux leakage. Increase in magnetic reluctance of flux leakage path is necessary to reduce the flux leakage. Accordingly, segmented rotor core is required for the size reduction of motor. In the case of segmented rotor core type, it is necessary to have complex mechanical structure to maintain circular rotor shape and fix to shaft. Since those additional structures seriously deteriorate productivity, plastic injection molding type rotor is suggested in this paper to solve the problem.

Design of Saliency-Based Sensorless-Controlled IPMSM With Concentrated Winding for EV Traction

This paper investigates the influence of the geometry design parameters of an interior permanent magnet synchronous motor with concentrated winding on the saliency-based sensorless drive feasibility. To evaluate the sensorless controllability of the motors, two different methods to estimate the rotor position error are proposed. By using the methods, the geometry design parameters in the stator are analyzed to figure out which ones have a positive effect on the sensorless drive. The analysis results show that the configuration of the tooth tip is one of the major factors in reducing the estimation error. Based on the results, an optimum design parameter is selected considering both the drive feasibility and the back electromotive force. Last, a final model is proposed and manufactured for electric vehicle traction. The validity of the proposed estimation methods and the design result are verified by the experiments.

Design of IPMSM having high power density for position sensorless operation with high-frequency signal injection and the method of calculating inductance profile

This paper estimates inductance profile well adapted to position sensorless control method based on the high frequency signal injection and proposes a direction to design for sensorless control in interior permanent magnet synchronous motor(IPMSM) having a high power density. In sensorless control, controller calculates the position of rotor at smallest d-axis inductance from high frequency injection. In order to satisfy this characteristic, this paper designs a motor having a large magnetic loading and a small electric loading. Inductance is calculated by the FEM using frozen permeability method and voltage equations of d-q axis are used to analyze characteristics of IPMSM such as torque, output power, current angle and efficiency.

Design of sensorless controlled IPMSM with concentrated winding for EV drive at low speed

The sensorless control based on the high frequency voltage signal injection method is typically used for detecting the rotor position of an interior permanent magnet synchronous motor (IPMSM). This technique is essential at zero and low speed operating region, where back electromotive force is extremely low. The sensorless-oriented machines require the same minimum value positions of the d-axis self-inductances, regardless of the rotor position. It means that the zero-crossing points of the dq-axis mutual-inductances varied with the rotor position should be constant as well. This paper introduces the design procedure of a saliency-based sensorless controlled concentrated winding IPMSM for vehicle traction, fulfilling the requirements mentioned above. The evaluating process of the sensorless drive feasibility by using finite element analysis (FEA) is proposed, with taking account of cross-coupling effect and saturation. Utilizing the evaluating method, some geometry design parameters are examined to figure out which ones have a positive effect on detecting the rotor position. Based on the influences of the parameters on the dr i ve feasibility, the design conditions for the sensorless drive concentrated winding IPMSM are determined. Finally, the proposed model applied with the geometry design conditions and the FEA results are shown. It is found that accuracy of the rotor position estimation is improved by means of the proper geometry design of the machines.

Hysteresis modeling using multi-Preisach model in electromagnetic computation

This paper presents particle interaction of hysteresis model with multi-Preisach model. A conventional analysis method is calculated using Everett density with the Gaussian distribution or the Cauchy distribution. In this paper, we propose fine method called multi-Preisach model method to calculate hysteresis model using several experiment data line. Multi-Preisach hysteresis model is provide the convenient and accurate novel method.

Estimation of Rotor Type Using Ferrite Magnet Considering the Magnetization Process

This paper deals with the post-assembly magnetization process of motors using ferrite permanent magnets (PMs). In order to meet the needs of mass production, most motors are magnetized post assembly. However, increasing complex shapes are required to maximize the flux of PMs. As a result, certain locations in the magnet are not fully magnetized by the magnetizing fixture due to insufficient magnetomotive force. Therefore, an analysis concerning the post-assembly magnetization is needed. In this paper, the concentrated flux spoke-type synchronous motor is analyzed with regard to the magnetization process. Owing to more flux, this motor is designed as a V-shape PM. Therefore, it is not fully magnetized according to magnet shape. By identifying the effect of the magnet shape, the magnetization level is compared by the amount of flux linkage between post assembly and at full magnetization. Finally, the back electromotive force is estimated by the post-assembly magnetization method according to the magnet shape.

Estimating unbalance mass of vertical axis washing machine by measuring current ripple of PMSM motor

In this study, first, an equivalent circuit of a permanent-magnet synchronous motor (PMSM) and a dynamic model of a washing machine are derived; second, a method for deriving the unbalance mass from the ripple of the current flowing through the electric motor is suggested; and finally experimental verification of the results are conducted.

Temperature prediction of oil-cooled IPMSM for in-wheel direct-drive through lumped parameter thermal model

This paper focuses on estimating the temperature of end winding, in which the highest temperature exists out of all the components, in Interior Permanent Magnet Synchronous Motor (IPMSM) for in-wheel direct drive. A lumped parameter thermal model of IPMSM is suggested with considering core, copper, mechanical, and eddy current losses, which are the heat sources and calculated from finite element analysis to improve the accuracy of the prediction. In addition, the thermal model is comprised of thermal resistances and capacitances determined by the configurations and the dimensions of motor. Finally, an oil-cooling system is covered with the concepts of thermal conductivity, density, specific heat at constant pressure, dynamic viscosity, and flow rate.