Yoshihiro Kawase

3-D finite element analysis of electrodynamic repulsion forces in stationary electric contacts taking into account asymmetric shape

The quantitative characteristics of stationary electric contacts in electrical apparatus have been given by means of some calculations, based on an artificial model of the current flow lines which highly simplifies the treatment. We have developed a 3-D finite element method by which the static characteristics of the electric contacts having asymmetric shapes can be analyzed. Repulsion forces in the stationary electric contacts with rectangular solid contact members as well as ones with cylindrical contact members are calculated by our method. The validity is confirmed by comparing with the results by the well-known Holm formula.

Dynamic Analysis Method of Two-Dimensional Linear Oscillatory Actuator Employing Finite Element Method

This paper proposes a dynamic analysis method of a 2-D linear oscillatory actuator. In this method, a magnetic field equation is coupled with motion equations of both linear and rotary motion of a mover employing the 3-D finite element method. The usefulness of the method is verified by comparing computational results with the measured resonant oscillation of the mover when it is operated at different frequencies for both motions

Numerical analysis of dynamic characteristics of electromagnets using 3-D finite element method with edge elements

This paper describes a new method for the accurate computation of the dynamic behavior of DC and AC electromagnets, such as used in contactors, relays and other electromagnetic devices. The method is based on the 3-D finite element method with edge elements taking into account the nonlinearity of the cores and the eddy current. For the dynamic analysis, it is necessary to change the 3-D meshes automatically. The analyzed model couples electrical, magnetic and mechanical systems of the electromagnets. Our method makes it possible to predict dynamic characteristics for the optimizing design of electromagnets. The validity of the new method is confirmed by experiments. >

Parallel Computing of Magnetic Field for Rotating Machines on the Earth Simulator

We developed a parallel computing method of the magnetic field for rotating machines by using the 3-D finite element method (FEM) with edge elements. In this paper, we describe the outline of the developed method and an optimization of the method for the Earth simulator, which is a vector-type parallel supercomputer in Japan. Moreover, the performance of the proposed method running on the Earth simulator is quantitatively clarified.

Effects of Skew Angle of Rotor in Squirrel-Cage Induction Motor on Torque and Loss Characteristics

We have developed a 3-D finite-element mesh modification method for skewed motors with an auto-mesh generator. Meshes modified by the auto-mesh generator are broken as enlarging the skew angel. In order to solve this problem, we have improved the modification method by solving Laplace equation. In this paper, characteristics of the skewed squirrel-cage induction motor are analyzed by changing the rotor skew angle using the meshes created by the improved mesh modification method.

3-D eddy current analysis in a silicon steel sheet of an interior permanent magnet motor

Interior permanent magnet (IPM) motors are widely used in various fields. It is important for the high-efficiency operation of IPM motors to clarify the iron loss. In this paper, the harmonic eddy current loss and the hysteresis loss of a piece of silicon steel sheet of an IPM motor are calculated using the three-dimensional finite-element method (3-D FEM). It quantitatively clarifies the effects of the phase difference between the induced voltage and the coil current on the torque and the iron loss (the eddy current loss and the hysteresis loss).

Numerical analysis of electromagnetic forces in low voltage AC circuit breakers using 3-D finite element method taking into account eddy currents

It is necessary for the optimum design of low voltage circuit breakers to analyze electromagnetic forces acting on the contact systems when the circuit breakers interrupt fault currents. In this paper, the forces which are known as the magnetic blowout force acting on the arc and the electromagnetic repulsion force acting on the moving contact arm are obtained by using the 3-D finite element analysis taking into account eddy currents. It is shown that our 3-D analysis is capable of evaluating a new design of contact systems in low voltage ac switching devices.

3D nonlinear transient analysis of dynamic behavior of the clapper type DC electromagnet

Clapper-type DC electromagnets are widely used for electromagnetic devices. For optimum design it is necessary to analyze the dynamic behavior of the electromagnet. A method to obtain the dynamic behavior of clapper-type electromagnets by 3D finite element analysis, taking into account the motion of the armature the eddy current, has been developed. This method makes analysis of the dynamic behavior of any electromagnet with a 3D shape possible. The validity of the method is confirmed by experiments. >

Dynamic Analysis of Linear Resonant Actuator Driven by DC Motor Taking into Account Contact Resistance Between Brush and Commutator

This paper describes a highly accurate computation technique to obtain the dynamic characteristics of a linear resonant actuator (LRA) driven by the dc brush motor and a magnetic conversion mechanism employing the 3-D finite-element method. In this calculation, the contact resistance between brush and commutator of the dc brush motor is taken into consideration in the electric circuit equation coupled with magnetic field equation. The influences of the contact resistance on the dynamic characteristics are quantitatively investigated, and the importance of the use of appropriate contact resistance is clarified through the comparison with the measurement.

Trajectory Analysis of 2-D Magnetic Resonant Actuator

A novel 2-D magnetic resonant actuator is presented, and the influences of frequency and phase of the input voltage waveform on the trajectory of the armature are computed using the three-dimensional finite element method.