Toshiyuki Todaka

Analysis of MPPT characteristics in photovoltaic power system

Abstract This paper describes characteristics evaluation of the power conditioner which has the function of Maximum Power Point Tracking (MPPT) by “mountain climbing method” through computer simulations. The generated power on the constant voltage control is compared to the one on MPPT with the load matching correction factor (Kpm). In this simulation, the following parameters are chosen, the rate of the voltage Δ V on changing the operating point and of the voltage ΔV c on checking the maximum point. As a result, the influence of these parameters on Kpm is showed and it is made clear that we should decide the MPPT parameters with care.

Dynamic analysis of a linear oscillatory actuator under feedback control

The dynamic performance of a linear oscillatory actuator (LOA) is computed using the finite element method, when it is operated by feedback control. In this computation, the magnetic field is perfectly coupled with the driving electric circuit and the kinetic motion of the mover. Comparison with the measured results verifies the validity of this analysis. The influence of feedback control function on the mover amplitude is also verified. In addition, the method of feedback control using the signal, obtained by the induced voltage from a sensing coil in place of a optical sensor is investigated. As a result of that, it is found that both control methods produce almost the same performance.

Comparison between the H-coil method and the magnetizing current method for the single sheet tester

Abstract In order to clarify the difference between the magnetizing current method and the H-coil method quantitatively, a special single-sheet tester which can separate the iron loss produced in the yokes is designed. The results measured show that 1.7–3.9% of power loss difference in the two methods is mainly due to the iron loss in the yokes.

A study on measurement of magnetostriction of silicon steel sheet by laser displacement meter

Abstract A measurement method of magnetostriction with a laser displacement meter on the market has been compared with the other optical method using laser Doppler vibrometer. In the measurement, the frame to excite the specimen is divided into three parts to fix the specimen, and the phase difference must be adjusted. It is shown that the λ p–p characteristics measured by laser displacement meter have good agreement with the other method.

A novel high power factor converter using a magnetic amplifier

A novel high power factor converter is presented in this paper. The proposed converter is a high-frequency forward converter controlled by a magnetic amplifier. This converter has no need of special control to correct the power factor. Power factor is corrected by the automatic variation of the saturation time of the magnetic amplifier according to the input voltage variation. The current stress of the transistor switch is low because this converter operates in the continuous conduction mode of the inductor current. The circuit operation is verified experimentally at a frequency of 500 kHz.

Thrust calculation of linear pulse motors using a combined technique employing the finite element method and the permeance analysis method

A technique for calculating the thrust of linear pulse motors is presented. This technique effectively uses the finite element method and the permeance analysis method to efficiently calculate the thrust with high accuracy. The utility of this technique was verified through the comparison of calculated and experimental results when applied to double-sided linear pulse motors with permanent magnets. The technique was applied to double-aided linear pulse motors, where the teeth of both the stator and the mover have simple rectangular shapes. The universality of this technique was verified by applying it to another model where the teeth of the mover have a trapezoidal shape. >

A study of characteristic analysis of the three-phase transformer with step-lap wound-core

In this paper, the analytic algorithm using equivalent magnetization curves is proposed for analysis of the three-phase transformer with wound-core in consideration of a step-lap joint or noncut structure. Influences of differences in step-lap joints and noncut structures on equivalent magnetization curves are examined using the algorithm. Influences on the exciting currents and core losses of the three-phase transformer are also examined.

A proposal for rotating machineries analysis by considering the unknown equal potential condition on FEM

This paper presents a technique for a magnetic field analysis using the Finite Element Method (FEM) which is applied to the rotatory movement of rotating machinery. The proposed technique uses only a couple of meshes because the nodes on an interface are joined under the unknown equal potential condition. This technique is examined by the analysis of the characteristics of brushless DC machines. Calculated results by this technique agree well with the measured ones, so that the utility of this technique is confirmed. >

Analysis and design of ZVS-PWM half-bridge converter with secondary switches

An improved zero voltage switching (ZVS) PWM half-bridge power converter with secondary switches is proposed and analyzed. The proposed power converter is controlled by PWM of the main switches using a novel switching sequence with a constant switching frequency. The main switches operate with zero voltage switching, and the secondary switches turn on and off with zero voltage and zero current. A small saturable inductor is added in series to the secondary switch in order to achieve zero voltage switching easily. From the analysis, steady state characteristics of the power converter and conditions of zero voltage switching are derived.<<ETX>>

Measurement of magnetic characteristics of silicon steel in any direction by RSST and SST : method and relationship

Abstract The magnetic characteristics of silicon steel sheet in any direction were measured by a RSST (single sheet tester for rotational loss) and a SST (single sheet tester). The specimens were cut from the same silicon steel sheet. Comparing the RSST and SST results, the effectiveness of measurements with the RSST was examined. The measured results of magnetization curves by the two methods were almost in agreement, but those of the losses were not.