Tsugio Yamamura

Physical Meanings Of The Gauge Conditions In Eddy Current Analysis

There are several ways to define the gauge condition in the A- phi method for 3-D eddy current analysis, e.g., the Coulomb gauge, the Lorentz gauge, etc. Unlike the Coulomb gauge, the physical meaning of the potentials in the Lorentz gauge is not obvious. A novel physical meaning of the Lorentz gauge is introduced, and the relationship between these gauge conditions in the A- phi method is described systematically from a physical viewpoint. >

A Novel Design Approach For Grasping Broad Characteristics Of Magnetic Shielding Problems

This paper presents a novel design approach composed of two sequential processes for 3D magnetic shielding problems, which results in the global optimum solution in a shorter time. The feature of the proposed approach is the adoption of the specific boundary element with permeability of infinity. Assuming the permeability of infinity enables us to regard the thickness of ferromagnetic shields as infinitesimal, and thus to simplify the investigated model adequately in numerical analysis. This reduces the number of unknown variables and saves us a large amount of CPU-time for grasping the broad characteristics of the model. Some numerical results that demonstrate the validity of the proposed approach are also presented.

|Iq| added flux weakening strategy for the rotor flux oriented control of a sinusoidal PWM VSI-fed induction motor

In a conventional field oriented control of an induction motor the rotor flux is assumed to be constant so that the torque is controlled by controlling the q-axis current only. In field-weakening region the rotor flux is decreased to achieve a very high rotor speed, as a consequence the available torque is reduced. On the other hand, to produce a maximum torque the rotor flux should be generated as much as possible. In this paper, a novel, simple field-weakening strategy, which provides a maximum torque capability for a sinusoidal PWM VSI-fed induction motor drive, is presented. The purpose of the proposed strategy is to add the absolute q-axis current to d-axis current reference so that proper flux and torque for any given torque-producing current reference are produced automatically. The maximum torque when it is required can be obtained over the entire field-weakening region without using machine parameters or special control strategy. A saturated sinusoidal PWM is used which limits the amplitude of the inverter voltage references. As an advantage, the effective output voltage as seen by the motor is boosted. Simulation and experimental results verify the performance of the proposed method.

Design optimization of electric machines based on the estimation of permeability distribution

We propose an optimization approach based on the estimation of permeability distribution, which enables us to make an effective objective function of optimization methods for the efficient design of magnetic devices. By the proposed approach, we can improve magnetic device characteristics by evaluating the deviation in the permeability distribution of the device as an objective function. In this approach, we separate the iron areas and calculate the permeability of each block to consider the permeability distribution. To verify the proposed approach, some numerical results, i.e., the shape optimization of ventilation holes in an induction motor, which demonstrate the validity of the proposed approach, are also presented. The optimization concept based on the estimation of permeability distribution is effective and can be readily applied to the practical design optimization of various magnetic devices.

Three-Dimensional FE Analysis for Evaluating Slit Effects in Linear Induction Motor

While a solid plate is usually adopted to the reaction plate of the linear induction motor (LIM), slits are often introduced to the plate in order to enforce the eddy currents effectively. In this paper, to find a suitable configuration of slits, we analyze the electromagnetic field of the LIM by 3-D FEM based on A-Φ method. Adding to the ordinary approach, we propose a face-element method with double nodes for Φ at slits to express the infinitesimal width of slits. In this paper, we adopt the periodical boundary conditions for simplicity of analysis, so it is virtually equal to analyze the usual rotating machine.