Akira Kohara

Permanent magnet assisted current superimposition variable flux machine

Electric and hybrid electric vehicles require traction motors that have a high power and efficiency over a wide rotation speed range . In order to satisfy these requirements and reduce the motor cost, variable flux reluctance motors (VFRMs) have been studied . Conventional VMFRMs have DC-field windings and armature windings. However, because there are two kinds of windings, the coil space factor decreases and the wiring becomes complicated . In order to solve these problems, we have developed a motor called the variable flux reluctance motor (CSVFRM) that does not have any DC-field coils, and instead uses current superimposition . In this paper, we propose a modified model whereby permanent magnets are introduced into the stator to increase the efficiency . The structure and operational principle of this machine are described and the N-T characteristics are computed by FEA.

Finite-Element Analysis and Experiment of Current Superimposition Variable Flux Machine Using Permanent Magnet

We have proposed a current superimposition variable flux reluctance machine that can control its torque constant. This machine can be operated by using a six-phase superimposition current composed of ac-armature and dc-field currents. In this paper, we propose a current superimposition variable flux machine using permanent magnets. The permanent magnets increase the dc magnetic flux. First, the structure and operational principle of this machine are described. Next, the torque characteristics are computed under vector control. Finally, the computed characteristics are verified by carrying out measurements on a prototype.

Study on a current superimposition variable flux reluctance machine with distributed winding

A current superimposition variable flux reluctance machine that can control its torque constant has been proposed. This machine requires only a single set of windings that can perform both armature and field winding functions simultaneously. Therefore, it is easy to apply a distributed winding and sprit core to our proposed machine. In this paper, a current superimposition variable flux machine using distributed windings is proposed and compared with that using concentrated winding. First, the structure and operational principle of the proposed machine are described. Next, the static characteristics are computed using 2D finite element analysis. Finally, the N-T characteristics are computed under vector control and the effectiveness of the proposed machine is discussed.

AC/DC current ratio in a current superimposition variable flux reluctance machine

Abstract We have proposed a current superimposition variable flux reluctance machine for traction motors. The torque-speed characteristics of this machine can be controlled by increasing or decreasing the DC current. In this paper, we discuss an AC/DC current ratio in the current superimposition variable flux reluctance machine. The structure and control method are described, and the characteristics are computed using FEA in several AC/DC ratios.

Current harmonics of a current superimposition variable flux reluctance motor

Traction motors for electric vehicles and hybrid electric vehicles require wide power band characteristics. In order to increase the power band, field weakening control is widely used in interior permanent magnet motors.

Current superimposition variable flux reluctance motor with 8 salient poles

Abstract We propose a current superimposition variable flux reluctance motor for a traction motor of electric vehicles and hybrid electric vehicles, which consists of 10 salient poles in the rotor and 12 slots in the stator. However, iron losses of this motor in high rotation speed ranges is large because the number of salient poles is large. In this paper, we propose a current superimposition variable flux reluctance motor that consists of 8 salient poles and 12 slots. The characteristics of the 10-pole-12-slot and 8-pole-12-slot current superimposition variable flux reluctance motors are compared using finite element analysis under vector control.

Characteristics of a wide power band variable flux reluctance motor

We have proposed a variable flux reluctance motor that requires only a set of coils for both the armature and DC-field currents. In this paper, the speed-torque characteristics of the motor are compared with those of IPM, switched reluctance and induction motors in terms of the power band. In addition, the phase current and motor efficiency are compared and discussed.