Electrical Engineering in Japan最新文献

This paper proposes the application of an adjustable speed diesel engine-driven power plant employing a doubly-fed induction generator to an isolated small-scale power system including renewable power sources. This type of power plant can contribute to fast and flexible power balancing regulations under vacillating power supplies such as wind, solar, and other renewable power sources. Installation of a battery system is also considered, which can assist coordinately with the power plant to augment renewable power sources in the isolated power system.

Recently, dynamic wireless power transfer (DWPT) for battery electric vehicles has been actively studied because it can enhance their cruising range and reduce their charging time. An SS type WPT circuit is simpler and more efficient than a WPT circuit with a filter, such as an LCC type WPT circuit. By contrast, the leakage magnetic field generated by the harmonic current is a problem that needs to be addressed. The leakage magnetic field is limited by the Radio Act and the Ordinance for Regulating Radio Equipment in Japan. This study aims to reduce the leakage magnetic field generated by the harmonic current using a high-frequency switching technology. The inverter and rectifier are operated using pulse width modulation (PWM) with a high carrier frequency. The effectiveness of the proposed method was experimentally verified using a GaN inverter and rectifier. As a result, the proposed method can drastically reduce the leakage magnetic field, especially, the magnetic field generated by the current harmonics of order greater than five.

A torque-difference-amplification torque vectoring differential (TDA-TVD), which is composed of a two-input-two-output system, has a great potential for cornering maneuverability; however, the overall controllability of slip ratio or driving force control is difficult owing to its complex mechanical structure. In order to enhance the controllability of TDA-TVD, this study proposes a design method to apply a driving force controller (DFC) with a decent slip ratio and driving force controllability, which was originally intended for independent wheel drive systems. An experimental verification on a slippery road using a real vehicle with the TDA-TVD indicated that the DFC can be applied to the TDA-TVD and that it improves the overall performance of the traction control.

Ball-screw-driven stages are widely used as feed systems of industrial equipment such as machine tools. Rolling friction in the stages causes a large tracking error called a quadrant glitch at a velocity reversal. Although the model-based friction compensation reduces the quadrant glitch, it often leads to a tracking error in the direction opposite to the quadrant glitch. This study aims to present a control system that reduces both the quadrant glitch and opposite-direction error. This is achieved by combining the model-based friction compensation and initial value compensation. The effectiveness of the proposed control system is verified by simulations and experiments with two-axis experimental setup.

As the mileage of the electric railway increases, the unevenness of the contact wire may separate the contact wire and the contact strip. Simultaneously, a disconnection arc discharge is generated by the molten metal bridge. This causes the contact wire to melt and evaporate causing it to break. A few studies have conducted experiments to prevent the contact wire from disconnecting. Based on the results thus obtained, they presented their hypotheses considering conditions sch as the current and time required for melting and evaporation of molten metal bridge and arc generation. In this study, a calculation method for the melting and disconnection phenomenon of the contact wire. Its mass increased when the currents from both sides of the contact wire were taken into consideration. Therefore, we obtained that the convection and radiation play an improtant role for calculation of the melting amount mass of contact wire.

This paper proposes a multi-port DC-AC converter with high efficiency and high-power density. The proposed circuit consists of a full bridge converter, a series active filter, and an unfolder circuit. The proposed circuit reduces the low switching losses owing to the square waveform operation with low switching frequency. In addition, the proposed converter improves the power density because the number of inductors is significantly reduced compared to the conventional multi-port converter. As the experimental result, the maximum efficiency of the proposed circuit reached 99.3%. Finally, the power density of the proposed converter is evaluated by the Pareto front curve. As the result, the power density of the proposed circuit was increased by 1.6 times in comparison with the conventional circuit.

In restricted slit-like space by two polymer plates, the effects of the space width, current and atmospheric pressure on arc electrical field were investigated experimentally for high-current air arc above several kA. As a result of the evaluations, it was found that the electrical field increases significantly with the pressure rise under condition near 0 MPa-g, and it increases with current in the restricted space at the width less than 10 mm. Comparing the electrical field in using polymer with glass for the restricted material, it revealed that the electrical field has current dependence caused by the space width in addition to increasing effect to above 1.5–2 times by the ablation or spallation effects of the polymer.

Robust stable feedback (FB) controller design against plant perturbation is crucial for industrial servo systems. However, since the controller parameter design generally requires expert skills and/or considerable labor by engineers, an autonomous controller design technology would be promising. This paper presents an efficient autonomous design method that optimizes the parameters of a cascade structure FB controller to achieve robust stabilization. Conventionally, robust stabilization is realized by imposing stability constraints on all the perturbed plant model sets in a parameter optimization problem. As a result, the design time would be much longer owing to the complicated optimization problem. The proposed method makes the parameter optimization considering robust stability more efficient than the conventional method, by simplifying the stability constraint definition and optimizing the specified circle radius for the stability constraint based on a bisection method. The effectiveness of the proposed method is evaluated through an example FB controller design for a laboratory galvanometer scanner.

To estimate in advance the high-frequency impedance of a motor, and its internal voltage distribution when an inverter surge is applied, a technique to derive the circuit constants of various parts of a motor based on electromagnetic field analysis and build its high-frequency equivalent circuit, where each turn of the coils is separately modeled, has been developed. By switching between 2D and 3D analyses and between 1-slot and 1-pole models to accelerate the calculation method and by automating them in parallel, the developed technique even enables non-experts to build an accurate high-frequency equivalent circuit of a motor. Based on the accuracy verification, the shared voltage of coils can be estimated with an error of 20% or less by considering the frequency characteristics of the resistance and inductance of each turn of the coils and modeling a lead wire in the measurement setup.