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Surge voltage is created on AC railcar bodies when a train raises its pantograph or when its main circuit breaker is switched. This surge voltage expands and vibrates at the end car as a result of the reflection effect in distributed-parameter circuit theory. Extreme surge voltage causes damage to and malfunction of on-board equipment, especially electronic devices such as train signaling and brake control systems. This paper outlines the mechanism behind the phenomenon of surge generation on AC railcar bodies, outlines the results of experiments for improving AC railcar ground systems, and discusses ideal ground systems for the prevention of extreme surge voltage.

Electromagnetic interference (EMI) is an unavoidable part of the application of power electronics to the traction circuits of railway vehicles. As it is particularly difficult to reduce the noise level radiated by EMI from various types of equipment and cables, we replaced ordinary inverter-motor cables with shielded cables and investigated their effect on noise reduction. The results verified a reduction effect exceeding 10 dB at 100 kHz with shield bonding at both ends. The shielded cables are effective in reducing noise on traction circuits in particular such as jumper cables or motor leads for which other noise reduction methods are inapplicable.

Surges on a rolling stock's body will occur when the train raises its pantograph. These surge cause damage or malfunction to on-board equipment. Expansion and vibration of the surge in the end car are found. Making clear those phenomena is required to design rolling stock that reduces a surge. In this paper, experiment and basic analysis confirm that inductance of a ground wire of a car body has close relation to behavior of surges.

In order to ensure electromagnetic compatibility between railway signaling systems and railcars, the interference current produced by railcars must be estimated. This paper proposes a new method for estimating the spectrum of low-frequency return-currents on direct current (DC) electric railcars. The proposed method is built on the hypothesis that the train’s electric power and kinetic power are equal, and only requires DC electric railcar characteristics such as starting acceleration and train mass in the estimation. A verification of test results indicate that the proposed method is effective at estimating the array (frequency and amplitude) of low-frequency return currents on DC electric railcars.

The superconducting Maglev system suspended by EDS (electrodynamic suspension) intrinsically has negative magnetic damping. In order to improve the magnetic damping, a linear generator was used by controlling the power factor of the current in the linear generator coils. A PWM converter and a simulator (using Micro Cap VI) were developed for this control. The article describes how to control the PWM converter and subsequently the power factor and the result of confirmation of this control method through simulation and synthetic bench tests.

We are developing a linear generator system as an onboard power source for Maglev vehicles. This linear generator system mainly consists of power collecting coils and has a Pulse Width Modulated convertor that functions as an impedance to compensate for reactive power in the generator circuit. The PWM convertor detects only instantaneous currents and realizes unity power factor control with excellent performance. Nevertheless, the measured impedance of the circuit differs from that estimated from the parameters of PWM convertor. The system becomes unstable when we set certain impedance values for the PWM convertor.We analyzed the control system as a closed loop digital control system and we derived impedance realized in the circuit We also obtained stable areas of impedance and currents from the conditions of stability of digital control system. The analyzed results of stability were in agreement with simulation results.

Presently electric locomotives and electric multiple units are designed by assuming high adhesion performance. However, they often cause problems of slip and slide of wheels. We developed a "Vehicle Traction Tester" to facilitate the analysis of wheel slip and slide and other phenomena at running performance tests. A.C. traction motor currents always vary to make it impossible to grasp the instantaneous current vector from one-phase current as is usually measured. We introduced a "Vector Calculator" that uses two-phase currents so that we can see the instantaneous amplitude and phase of the current vector. Furthermore, we developed a new "Train Running Resistance Analyzer" that shows running resistance on a display on a real time basis and makes statistical data processing faster and easier.