To improve train ride quality, a lateral semi-active suspension has been developed and subjected to a running test. Typical tilting trains of Japan have too small resistance in their tilting mechanism to apply this semi-active suspension system. To make an effective semi-active suspension, a changeable tilting damper has been developed and tested with semi-active suspension. As a result, the following have been verified. (1) The semi-active suspension without changeable tilting damper suppresses the lateral vibration of carbody about 20-30%. (2) Its performance becomes worse at the end of a traverse curve. (3) The changeable tilting damper improves the performance of semi-active suspension. (4) Using both semi-active suspension and changeable tilting damper is an effective way to improve the ride comfort of tilting trains.
Railway Technical Research Institute (RTRI) and Hokkaido Railway Company have jointly developed a steering pendulum bogie of a series 283 diesel power car limited express in an effort to shorten the travel time between Sapporo and Kushiro. The bogie is equipped with link type wheelset steering device connected with a bogie rotational angle, in order to reduce lateral forces between wheel and rail. The tilt roll center height was set at 1900 mm from the rail surface level to improve riding comfort and avoid wheel unloading. We have also developed a new air servo cylinder for tilting. Tilt mechanism took into consideration the severe winter weather. This paper describes the characteristics and mechanism of the bogie.
We are now making research and development efforts on a new railway system which is driven by linear motors, supported by iron wheels, and guided by electromagnets. The guidance force is produced by electromagnetic attraction between on-board electromagnets and track-side guide rails. As one step in the development, we examined the performance of the electromagnetic guidance control system by using a rotary disc type experimental facility. Frictional force between the supporting iron wheel and rail may affect the guidance control system as disturbance. To compensate for the non-linearity and modeling errors of the frictional force, we introduced a disturbance observer and feed forward control method. Kalman filter which estimates state variables was also used with LQI control to obtain satisfactory performance. This paper presents the system configuration and experimental results.
PWM-controlled line-side GTO converters of modern AC electric vehicles inject harmonic currents depending on their carrier frequency into the feeding overhead line. When they coincide with the variable resonance frequency of the line-distributed constants, the resonance currents become considerably high in amplitude and cause damage to the substations protection systems. Various counter-measures are taken to cope with this problem. In the case of trains equipped with a number of PWM converters, the problem is solved by the phase shifting operation method. For short trains, however, other solutions should be considered. Our proposal consists of parallel-connected active power filter. To verify the proposed method, a trial 200 kVA single-phase active power filter on board a vehicle was tested in the field and experimental results.
To analyze slip phenomena, we propose a new practical readhesion control for electric railway vehicles with three-phase drive. The keypoints are optimized axle velocity detection, detection of small slip, slight reduction of torque and torque recovery at readhesion. By running tests with a prototype Shinkansen train "STAR 21", we obtained good results. Nevertheless, slip-readhesion iteration occurs under very bad wheel-rail conditions. So we introduced wheel-rail adhesion prediction in addition and succeeded in utilizing as much adhesion force as possible under any wheel-rail condition. Especially this control has remarkable performance under very bad conditions such as icy rail, steep gradient etc.
AC railway vehicles controlled by PWM line side converters inject harmonic current into the feeding overhead line. This causes problems such as resonance expansion which will lead to malfunctions or overcurrents at substations and electromagnetic interference with signalling systems. Normal active filters only shift the harmonic frequencies to a higher range. A novel harmonic compensator produces an exact counter mmf which becomes sinusoidal in the main transformer main flux then becomes sinusoidal. Experimental results from a small model of a Japanese AC railway vehicle are described. Especially, harmonic currents are very well suppressed in the 3-4 kHz frequency range that coincides with the signalling band. As a result, this novel harmonic compensator and its method appear promising for use in any 50 Hz, and 60 Hz fed PWM controlled AC railway traction system.
Inverters have made a great progress due to the development of power semiconductors. Smaller power convertors offer larger passenger rooms and higher productivity. Convertors on-board can be much smaller if we utilize 3.3 kV or 4.5 kV IGBTs and two-level convertors instead of three-level ones. Smaller loss and smaller harmonics are always expected for convertors to enable self-cooling and avoid additional measures for EMC requirements. If 10-40 kV power semiconductors are available, it may be possible to realize transformerless railway vehicles for the 25 kV ac system by assigning convertors with the role of the main transformer in the traction circuit.