In order to improve the mileage per charge of battery electric vehicles (BEV), dynamic wireles power transfer systems are being developed. There are some problems such as is the wide gap between coils when mounted under the floor of a vehicle, and the effect of foreign objects between coils on power transmission. In-wheel coils, in which the coils are placed inside the wheel, have been proposed as a solution to these problems. However, they a plastic wheel such as CFRP and cannot reduce the gap between coils. In this paper, we propose a coil configuration in which the coils are placed inside the tire and the wheel. This configuration has the advantage of using a conventional aluminum to reduce the gap between coils. The effectiveness of this method is demonstrated via simulations and experiments.

Recently, concerns over global environmental problems have increased. An energy-saving operation is one of the most important technologies in railway engineering as it exerts a great effect when compared to other recent hardware techniques, such as the improvement of traction power control. Energy-saving operations are analyzed by mathematical calculations and their results are verified by on-track tests. However, verification tests and experiments are time-consuming; therefore, a simple verification method is required. In this paper, a simple energy measuring method is proposed using a satellite positioning device. The method also includes data processing using a low pass filter. The results show that the energy consumption determined using our proposed method is similar to that obtained by the conventional verification method for railway operation, indicating the appropriateness of our method.

Common-mode choke (CMC) plays an important role in suppressing the leakage current produced during the operation of pulse width modulation (PWM) inverters. However, when the common-mode path exhibits a large series stray capacitance, particularly the capacitance produced by long shielded cables, the CMC core reaches magnetic saturation. This paper presents a technique of selecting a suitable carrier frequency for the inverter to suppress the magnetic saturation of the CMC. First, the analytical approach leads to a non-saturation condition, and clarifies the maximum and minimum carrier frequency design conditions. Subsequently, the effect of the design is demonstrated by a non-linear circuit simulation and experimental tests using an actual inverter system demonstrate the effectiveness of the design technique.

In recent years, with the development of information and communication technology, automatic train operation has been attracting attention. In this paper, we propose an automatic train group control operation using a traffic forecasting system. Our simulation shows that the proposed method avoids unnecessary acceleration/deceleration of trains and minimizes delay time when the train schedule is disrupted, compared with conventional automatic train operation.

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.

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.

This paper proposes a novel torque controller in a direct torque control (DTC) system for permanent magnet synchronous motors (PMSM). A reference flux vector calculation (RFVC) DTC uses a PI controller for torque control and can be applied with a PWM voltage-fed inverter. The RFVC DTC's controller can be designed using classical control theory with a linear transfer function by analyzing the relationship between the torque, torque angle, rotor speed, and angular frequency of the stator flux-linkage vector. In contrast, the conventional equivalent modeling method is only applicable with high control gain. At a lower control gain, the convergence performance degrades in the conventional model. Therefore, the torque control characteristics are improved by the proposed system, which is based on the decoupling rotor speed in the torque control system. Simulation and experimental results confirm the validity of the proposed system.

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 such 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 amount mass of contact wire caused by melting and evaporation of molten metal bridge and arc generation is developed in order to elucidate 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 important role for calculation of the melting amount mass of contact wire.

In recent years, train delay on a daily basis has become a major concern in Japan. Although there are many existing studies that have analyzed train delay, most of them are based on the extent of train delay. These studies do not explicitly describe the influence of train delay on passengers. Furthermore, the studies that evaluate the influence of train delay on passengers only estimate the overall influence in the target line caused by an accident, and the results obtained are insufficient for evaluating countermeasures to improve punctuality. In this study, we developed a new method of evaluating train delay to understand its influence on both other trains and passengers. This method quantitatively analyzes the impact of a single delay, by estimating its range of propagation and the number of affected passengers who are estimated to reach their destinations behind schedule. We applied the new method to the commuter rail line and found that train delay around a large station has a relatively large influence on passengers. We confirmed that the proposed method can reflect the total volume of affected passengers, and extract sets of trains and stations, for which countermeasures should be taken to improve punctuality.

This study proposes a simple sensorless-control method for permanent magnet synchronous motors. The controller does not employ any phase-locked loop (PLL) blocks, which provide the angle of the rotating reference frame. The instantaneous-voltage-reference direction of the inverter is directly utilized for setting the angle of the gamma-delta frame. Experiments reveal that the proposed controller appropriately drives a 400W IPM motor almost without any motor parameters. Additionally, the drive system achieves a high transient performance in terms of motor speed.

In DC-electrified railway systems, the Filter Capacitor (FC) voltage of the traction inverter of the regenerative braking train increases with an increase in the distance between the powering train and the regenerative braking train. In this case, the light-load regenerative brake control sometimes causes continuous oscillation of the FC voltage of the regenerative braking train. This paper proposes a method based on a linearized model to design the controller including PD compensators to suppress this continuous electrical oscillation.