Jin-woo Cho

Characteristics Comparison of a Conventional and Modified Spoke-Type Ferrite Magnet Motor for Traction Drives of Low-Speed Electric Vehicles

Rare-earth magnets have been widely employed for traction drive motors of hybrid and electric vehicles (EVs) due to high energy density. Nevertheless, the magnets have critical problems such as unstable supply and high cost. Recently, in order to solve the problems, a variety of motors not using rare-earth materials have been reviewed, such as an induction motor, a switched reluctance motor, and a spoke-type ferrite magnet motor (FMM). In this paper, a modified spoke-type FMM with a novel rotor configuration was presented for a traction motor of low-speed EVs. The characteristics of the modified spoke-type FMM are numerically compared with a conventional spoke-type FMM at the same design condition. Finally, the modified spoke-type FMM is fabricated and tested in order to verify its performance and feasibility.

Investigation and Experimental Verification of a Novel Spoke-Type Ferrite-Magnet Motor for Electric-Vehicle Traction Drive Applications

In order to exhibit high performance, traction drive motors that use rare-earth magnets have been mainly applied to hybrid and electric vehicles (EVs). However, the raw materials of the magnets have critical issues such as unstable supply and high cost. Thus, a variety of motors not using rare-earth materials have been intensively developed for the traction motor. Nevertheless, it has limitation in increasing the performance of such motors without the use of rare-earth magnets. Accordingly, this paper investigates the availability of a spoke-type ferrite-magnet motor (FMM) with a novel rotor configuration for EV traction motors. In particular, the proposed motor has two rotor designs, and its characteristics based on finite-element analysis are compared according to each rotor design. Furthermore, various mechanical characteristics such as thermal stability, structural safety, and acoustic noise are checked in the design stage of the spoke-type FMM. Finally, the spoke-type FMM is tested in order to verify its performance and feasibility, including vehicle installation and on-road test in LA4 city driving mode.

Characteristics comparison of a conventional and modified spoke-type ferrite magnet motor for traction drives of low-speed electric vehicles

Rare-earth magnets have been widely employed for traction drive motors of hybrid and electric vehicles (EVs) due to high energy density. Nevertheless, the magnets have critical problems such as unstable supply and high cost. Recently, in order to solve the problems, a variety of motors not using rare-earth materials have been reviewed such as an induction motor, a switched reluctance motor, and a spoke-type ferrite magnet motor (FMM). In this paper, a modified spoke-type FMM with a novel rotor configuration is presented for a traction motor of low-speed EVs. The characteristics of the modified spoke-type FMM are numerically compared with a conventional spoke-type FMM at the same design condition. Finally, the modified spoke-type FMM is fabricated and tested in order to verify its performance and feasibility.

A numerical model for predicting vibration and acoustic noise of IPMSM

A numerical model to predict acoustic noise due to electromagnetic forces in interior permanent magnet synchronous motor (IPMSM) is presented and applied to a spoke-type ferrite magnet motor for electric vehicles. The methodology includes the calculation of radial magnetic forces applied on tooth surfaces to account for the effect of motor vibration on the noise. Fundamental and high order harmonics of the magnetic forces are then obtained via FFT process. A model was developed to predict sound pressure levels based on an indirect BEM solver. Actual sound pressure levels were measured to validate the model and the results showed that the model predictions agree well with the observations from the experiments.