Katsumi Kesamaru

Eddy-current loss analysis in PM of surface-mounted-PM SM for electric vehicles

Recently the rare-earth magnet NdFeB has been applied to electric vehicles. The rise of temperature due to eddy current loss in the permanent magnet (PM) leads to serious deterioration of the PM, especially in high speed operation. This paper describes an original analysis of the eddy current loss in the PM of a surface-mounted-PM SM for electric vehicles. The finite element analysis makes clear the effect of eddy current loss in the PM of the PM synchronous motor (SM) in the high speed range of operation including field weakening.

Interconnection system with single phase IGBT PWM CSI between photovoltaic arrays and the utility line

The single-phase utility interactive photovoltaic (PV) system, including the insulated-gate bipolar-transistor (IGBT) current-source pulse-width modulation (PWM) inverter with two auxilliary IGBTs is described. The system configuration, its operation, and experimental results which include steady-state characteristics with waveforms are presented. It is shown that the system can supply a utility with maximum power corresponding to the insolation with sinusoidal current waveforms at unity power factor. The modulation index and firing angle are fixed, and there is no need for feedback control. In case of emergency, the system can be instantaneously disconnected from the utility line by turning off all the main IGBTs. Simultaneously, the two auxiliary IGBTs are turned on to let the DC current circulate through these IGBTs, the PV array, and the DC reactor.<<ETX>>

Analysis of voltage-adjustable brushless synchronous generator without exciter

Two types of brushless single-phase synchronous generators without a rotating exciter have been proposed. The theoretical and experimental results of their characteristics are presented. The stator of the generator is equipped with two separate windings having different pole numbers: one is the single-phase load winding and the other is the DC exciting winding. It has been verified theoretically and experimentally that the output voltages are kept nearly constant even under constant stator DC current, and that the voltages can be adjusted in a wide range by the stator DC current. The proposed generators are useful not only as constant-speed generators, but also as maintenance-free variable-speed variable-load generators, such as wind generators. >

FEM simulation of novel small wind turbine generation system with synchronous reluctance generator

This paper describes a small wind turbine generation system with synchronous reluctance generator (SynRG). SynRGs are robust and inexpensive. In addition, SynRG has no cogging torque. Hence, wind turbine generation system with SynRG can achieve smooth start at low wind velocity. The rotor design of proposed SynRG is multi flux barrier type. With the finite element analysis (FEA) software, the characteristics of SynRG are brought out, and the performance of wind turbine generation system with SynRG is simulated by FEM analysis coupled with the motion equation of the wind turbine generation system under the maximum power point tracking control. In this paper, the constant wind test and the quasi-natural wind test are conducted. The results of these simulations indicate that the wind turbine generation system with SynRG has good performance, especially in starting phenomena.

Analysis of brushless four-pole three-phase synchronous generator without exciter by the finite element method

The magnetic field analysis of the original brushless four-pole three-phase synchronous generator is described. The rotor of the generator consists of short-circuited field coils with diodes. The output voltage can be kept constant by adjusting the stator DC current. To analyze the characteristics of this generator, the direct finite element method with which the values of currents can be directly obtained together with magnetic vector potentials is applied. It is found that the results of this theoretical analysis agree well with the experimental results.<<ETX>>

Magnetic field analysis of brushless 2-pole synchronous generator without exciter by finite element method

Brushless two-pole three-phase and single-phase synchronous generators are described. The rotor of these generators consists of field windings short-circuited with diodes. The magnetic field of the generators is analyzed by the finite-element method. By means of plotting the flux distributions inside the generators, the suitable geometry of the rotor pole shoes is investigated, and the self-excitation of the rotor field is visually confirmed.<<ETX>>

FEM simulation of positioning systems using segment type surface PMSM

This paper describes the FEM analysis of positioning systems using segment type surface PMSM. The systems are simulated by using FEM taking into account the motion equation of the motor drive. The transient phenomena of positioning system are strictly analyzed by considering the cogging torque of PMSM. In addition, the effect of the step response of positioning system on field weakening control of PMSM is investigated. It is confirmed by simulation results that the proposed segment type surface PMSM has high-speed positioning performance compared with conventional radial type PMSM.

Novel PWM-VSI fed brushless three-phase synchronous motor

A description is given of a novel brushless stator DC-excited synchronous motor without a rotating AC exciter. The DC-exciting winding, having pole numbers different from that of the main three-phase winding, is incorporated in the stator. The rotor circuit consists of field coils short-circuited with diodes. The principle together with analytical and experimental studies of the PWM-inverter-fed brushless synchronous motor is explained. It is found that the power factor of the motor can be easily controlled by adjusting the stator DC current.<<ETX>>