Examination of an Interior Permanent Magnet Type Axial Gap Motor for the Hybrid Electric Vehicle

Abstract

--Hybrid electric vehicles (HEVs) that emit less carbon dioxide have attracted much attention and rapidly become widespread, but further popularization of HEVs requires further technical advancement of mounted traction motors. Accordingly, our research group focuses on axial gap motors that can realize high torque density. In this paper, an axial gap motor with a novel interior permanent magnet (IPM) rotor structure is proposed and an examination of the proposed motor at the actual motor size of an HEV is presented. For comparison, we selected the newest radial gap-type 60 kW IPM synchronous motor equipped in the third-generation Toyota Prius. Under the condition that the size of the proposed motor be the same as the comparison motor, we confirmed through three-dimensional finite-element analysis that the proposed motor could output twice the maximum torque of the comparison motor. In addition, a comparison was made with a previously reported conventional IPM-type axial gap motor, and the proposed motor was found to be more effective in generating reluctance torque. Moreover, the proposed motor exhibited sufficient durability to irreversible demagnetization of the permanent magnets, to stress caused by rotating the rotor, and to unbalanced electromagnetic forces caused by axial rotor eccentricity.

A topology selection consideration of electrical machines for traction applications: towards the FreedomCar 2020 targets

“…axial machines, it is easy to uble rotor machines. This is h axial machines [37][38][39][40], as arder to scale than radial orque is proportional to the nd independent of the stack the torque produced, the ased and so different size nufactured. This inability to ue when considering traction y to be produced for a range Axial flux machines are often designed for traction applications due to their high torque density, but have not been considered for the FreedomCar 2020 targets.…”

“…In this case the requirements allow a large machine diameter, with a low active length, to produce a large torque at a relatively low speed (2800 rpm). Another example of axial flux machines being used for traction is given in [39] where an axial flux machine is designed to approximately the same dimensions as the Toyota Prius IPM machine. It is shown that the axial flux machine can produce over twice the torque of the Prius IPM motor, although this is at half the speed.…”

Design and Analysis of Interior Permanent Magnet Synchronous Motor Considering Saturated Rotor Bridge using Equivalent Magnetic Circuit

“…The equation for specific magnetic loading is expressed as (1) where α p is the effective pole arc coefficient, φ f is the linkage flux of the air-gap, τ p is the pole pitch, and L stk is the stack length of the motor.…”

“…In particular, hybrid electric vehicle (HEV) technologies, which contribute to reducing global warming, have attracted increased attention, and HEV market penetration has increased rapidly. To further advance of HEV prevalence, electric traction motors with advantageous properties, such as small size, high power density, and high efficiency, are necessary [1]. One suitable motor type is the permanent magnet (PM) machine.…”

Investigation of the Cooling and Thermal-Measuring System of a Compound-Structure Permanent-Magnet Synchronous Machine

“…The Toyota Prius has drawn increasingly wide attention from a great many automobile manufacturers and consumers in recent years, owing to its low energy consumption and excellent vehicle performance [1][2][3][4][5]. This mainly benefits from the utilization of a planetary gear unit for power splitting in the Prius hybrid system [6][7][8].…”