Masahiro Aoyama

Estimation of rotor current based on mathematical model of wound-field synchronous motor self-excited by space harmonics

This paper describes estimation of the rotor winding current based on a mathematical model of a self-excited wound-field synchronous motor where the space harmonics power is utilized for the field magnetization instead of the permanent magnets. The operation principle of the proposed motor is explicated by a voltage equation on the synchronous rotating reference frame. Furthermore, the rotor winding current is compared between the FEM based simulation and the mathematical calculation. Consequently, it has been confirmed that both operation characteristics in the steady state agree very well and indicate similar tendency.

Permanent-magnet-free-synchronous motor with self-excited wound-field technique utilizing space harmonics

This paper describes a permanent-magnet-free synchronous motor where space harmonic power is utilized for the field magnetization instead of permanent magnets. The stator has a three-phase concentrated winding structure, and the rotor has two types of windings, i.e., an induction coil that retrieves mainly the second space harmonic and a field coil for the field magnetization. The two coils are connected via a center-tapped full bridge diode rectifying circuit. The principle of self-excitation utilizing space harmonics power is conducted, and the mathematical model is discussed. In addition, experimental test results are demonstrated compared with interior-permanent-magnet synchronous motor for HEV application.

Proposal of electrically reversal magnetic pole type variable magnetic flux PM motor

This paper describes a variable magnetic flux PM motor in which space harmonic power is utilized for the magnetic flux weakening, automatically. The stator has a toroidally-concentrated winding structure, and the torque generation surfaces are composed of three air-gaps which are single radial-gap and double axial-gaps. The radial-gap rotor is a consist-magnetized PM rotor and the axial-gap rotors are self-excited wound-field rotor. The axial-gap rotor can retrieve a space harmonic power, which is inevitably generated by a concentrated winding structure, for magnetomotive force. A mechanical design of the prototype is revealed, and the operation principle of the automated-magnetic flux weakening is clarified through the FE-analysis. In addition, actual prototype machine is introduced. Consequently, the effect of automated-armature line voltage decrease is investigated with respect to rotation speed increase.

Proposal of pancake axial-air-gap-type self-excited wound-field synchronous motor

This paper proposes a pancake type synchronous motor where the space harmonics power is effectively utilized for the field magnetization instead of the permanent magnets. The pancake axial-gap structure, i.e., a single stator with double rotor configuration, can take great advantage to improve the mutual inductance which is indispensable for self-excitation of the magnet field. The advantages of the proposed motor in terms of the torque density is clarified with the FEM based simulation results. In addition, preliminary experimental test result is demonstrated from the viewpoint of the principle of self-excitation.

Proposal of self-excited wound-field magnetic geared motor for HEV application

This paper describes a permanent-magnet-free magnetic geared motor where magnetic flux variation in differencial frequency between stator rotating magnetic field and rotor rotation speed is effectively utilized for field magnetization instead of permanent magnets. The operation prin ciple of t he self-excitation with diode rectifier on rotor winding circuit is discussed in this paper. Magnetic circuit design and structural design of downsized prototype machine were performed for the purpose of verification of the self-excitation principle. In addition, the adjustable speed drive characteristics of proposed motor are investigated by FE analysis.