Won-Ho Kim

A Study on the Optimal Rotor Design of LSPM Considering the Starting Torque and Efficiency

This paper presents the optimal rotor design method in a single-phase line-start permanent magnet motor (LSPM) considering the starting torque and efficiency. To consider nonlinear characteristics, the design process is comprised of the FEM and analytical method. During this study, permanent-magnets and cage bars were designed using the magnetic equivalent circuit method and the barriers that control all magnetic flux were designed using the FEM, and the tradeoff of starting torque and efficiency is controlled by weight function in Taguchi method simulation. Finally, the performance of the optimal model is compared with those of conventional models.

Optimal PM Design of PMA-SynRM for Wide Constant-Power Operation and Torque Ripple Reduction

This paper presents the design process of permanent magnets to enable a wide range of constant-power operation and reduce the torque ripple by using analytical and numerical methods in PMA-SynRM. For a wide range of constant-power operation, the minimum d-axis flux-linkage of the permanent magnet is designed to be close to zero. Moreover, the unbalanced flux density in each segment is adjusted by changing the size of each permanent magnet to reduce the torque ripple. Finally, control simulations and experiments will be conducted to prove the validity of the suggested process.

Parameter Design of IPMSM With Concentrated Winding Considering Partial Magnetic Saturation

The interior permanent magnet synchronous motor (IPMSM) is usually applied to the traction motor in the hybrid electric vehicle and the electric vehicle due to its high-power density and wide speed range. In this paper, the IPMSM with concentrated winding for a 110 cc electric motorcycle is introduced. Its design was improved for high efficiency and a wide speed operation range. The output characteristics were also analyzed according to the partial magnetic saturation of the shoe and web in many variables. Because partial magnetic saturation affects the harmonics and the eddy current loss of the permanent magnet, it was confirmed that the output characteristics of the motor significantly changed. As a result, the new shape and the design parameters for which the partial magnetic saturation was considered were obtained. Higher level efficiency and a wider operating range than with the base model were confirmed.

Inductance Calculation Method of Synchronous Reluctance Motor Including Iron Loss and Cross Magnetic Saturation

This paper presents the novel method inductance calculation of a synchronous reluctance motor (SynRM). Synchronous inductances (Ld and Lq) are exceedingly important factor of SynRM to drive. Because of self axis current as well as the other axis current, inductances of d-axis and q-axis of SynRM are varied. Using an equivalent circuit model for expressing d-axis and q-axis inductance variation, the authors elicit suitable equation considering iron loss and cross magnetic saturation. Parameters of motor to use calculation are gained by AC signal test.

Method of Current Compensation for Reducing Error of Holding Torque of Permanent-Magnet Spherical Wheel Motor

A permanent magnet spherical wheel motor, which consists of magnets on rotor and coils on spherical stator, is able to operate on 3-D space as using magnetic alignment torque generated from between coils and magnets. Especially the shaft can be tilted stably by optimized coil position on stator. Because, however, the spherical wheel motor has feature of 3-D structure as relative position between coils and magnets, stable holding torque for rotor position should be analyzed as function of the tilt degree of a shaft. The characteristic of stable holding torque can be changed nonlinearly by the alpha and beta degrees of a shaft. Therefore, when reference current is commanded at coils, the shaft cannot be tilted to the reference position exactly for the nonlinear characteristic. In this paper, for improving the nonlinear phenomenon of holding torque, the authors research and improve a current compensation function to increase stable operating range. Also, the compensation function was estimated by using torque ripple computed from torque simulation.

The optimal design of the rotor bar for LSPMSM considering the starting torque and magnetic saturation

This paper presents the optimal design method of cage-bars in a single-phase line-start permanent magnet synchronous motor. This method consists of two procedures. First, the basic design of cage-bars is made by analytic method of an induction motor. But, this method cannot consider nonlinear characteristic as magnetic saturation and leakage flux. Therefore, at second step, for considering the nonlinear characteristics, the optimal design of cage-bars is performed by the response surface method (RSM) and Pattern Search Algorithm (PSA).

Loss analysis of the IPMSM for HEV

IPMSM has been often developed for HEV because it has a high power density and a wide range of operations. However, an armature reaction occurs from the high current and also the hysteresis loss from electrical steel of rotor and stator and the magnet is pretty high due to the high speed driving. Moreover, for IPMSM, there are hardly any accurate specifications or studies to verify the loss through simulative experiment. In this study, the hysteresis loss and eddy current loss are calculated as well as their correlations along with the changes of the current magnitude, current phase angle, and driving speed. In addition, an experiment on loss separation is suggested and its validity is verified through a comparison with the simulation.

Design and comparison between IM and PMSM for hybrid electrical vehicles

Considering the development and the prototype presentations of electrical and hybrid electrical vehicles over the last decade, one can see that several machine types were applied the direct current machine (DC), induction machine (IM), the permanent magnet synchronous machine (PMSM), and the switched reluctance machine (SRM). However many comparison study shows the IM or PMSM is suitable for hybrid propulsion system [1]–[4] and this type of motor is mostly adopted in the automotive industry. The IM is generally adopted in the USA and Europe while on the other the PMSM is adopted in Japan. It is very hard to say which one is better but it depends on vehicle constraint, for example, output power, power density, efficiency, so on. In this paper, the two type of machine is compared in different output power. It shows the power density as increasing output power, and it discusses the critical issue of the iron loss according to the output power.

Robust Torque Control of DC Link Voltage Fluctuation for SynRM Considering Inductances With Magnetic Saturation

This paper presents the control method that inverter output keeps to linear to reference voltage of Synchronous Reluctance Motor (SynRM) using DC Link voltage Synthesis. This method is reduced torque ripple considering parameters with magnetic saturation. To estimate parameters of inductances for SynRM, the proposed method uses recursive least square (RLS) estimation algorithm. The estimated inductances are used for calculating torque and DC link voltage. The Inverter output voltage cannot be displayed to linear about inverter reference voltage if Real DC Link voltage is different from DC Link voltage of PWM amplitude. Also, the over-modulation is linearity broken if reference voltage is out of range. Torque ripple generates the vibration and noise of a motor. This paper proposes the control method so that the torque ripple decreases and the linearity of inverter output keeps using the DC Link voltage Synthesis. The proposed control method is verified by computer simulation and experiment.

Effect of the Incomplete Magnetization of Permanent Magnet in the Characteristics of BLDC Motor

The incomplete magnetization is a frequently occurring phenomenon during the magnetizing process of magnets in precision motors because they use ring magnets which are not segmented. Even a small variance of the incomplete magnetization can make critical changes in the characteristics of motors like cogging torque profiles and the cogging torque profiles play an important part in reducing the noise and vibration of motors. So, the modeling of the incomplete magnetization area of magnets becomes a critical point in the analysis of the precision brushless dc motors. Conventionally, the modeling method of the area is to change the magnitude of the magnetization vector according to position angles in a magnet but the authors propose a novel method for modeling the incomplete magnetization area. This method is compared with the conventional method and verified by the measured cogging torque profile.