Satoru Sone

Traffic dynamics of automated transit systems with pre-established schedules

The authors examine the traffic dynamics of automated transit systems in which a fixed number of vehicles are operated according to a preestablished schedule along a single loop track with on-line stations. After discussing some roles of margin in the schedule, they propose a traffic control algorithm under disordered operation together with criteria for the system performance. Several simulations are executed to examine the traffic dynamics and to demonstrate the usefulness of the proposed control algorithm. A detailed passenger flow model is included in the simulator which gives the exact number of passengers, both in vehicles and at stations.

A novel prediction method of acoustic magnetic noise based on induction motor's NHCC function

When an induction motor is driven by a pulsewidth modulation (PWM) inverter, acoustic magnetic noise caused by harmonics of the induction motor input is a serious environmental problem. In this paper, a novel prediction method of acoustic magnetic noise is proposed. Acoustic magnetic noise emitted from an induction motor is considered as the function of harmonic components of induction motor current. The acoustic magnetic noise versus harmonic current characteristic (NHCC) function is defined. This NHCC function describes the response of acoustic magnetic noise to a single-frequency harmonic current. Based on the NHCC function, acoustic magnetic noise can be predicted very easily and accurately, simply by the calculation of harmonic components of the induction motor current. By making use of this method, the difficulties of the conventional prediction method, such as the complex calculations of magnetic force, mechanical resonant frequencies, and sound radiation efficiency can be avoided. This novel method can be used as a tool for environmental noise management and evaluation of low-acoustic magnetic noise characteristics of different inverter PWM control methods.

Improvement of traction power feeding/regeneration system by means of energy storage devices

Since ac motor traction was widely introduced in early 1990s, distributed traction systems have received much more popularity through better braking characteristics and much less disadvantage due to many traction motors with less individual power thanks to almost no requirement for maintenance works. But if compared with rheostatic brakes, maximum braking power has to be much less because of substantial dependency upon catenary voltage. At the other hand, in road vehicle application, the so-called hybrid car, which uses both battery driven electric motor together with internal combustion engine, has been very popular recently due to its superior petrol consumption rate. For this application, various types of electric energy storage devices (ESD) such as lithium ion battery and electric double-layer capacitor (EDLC) have also been improved. The author will first present state of the art technology of these two topics, especially in Japan, and then proposes the combination of these two important elements, regenerative braking and ESD together with various advantages. The most important feature of this combination is easy realisation of high power regeneration without much burden to catenary system and installed traction power, which can be realised by using overvoltage characteristics of the motor and by charging/discharging of excess power to/from either or both of on-board or wayside ESD.

INNOVATIVE POWER SUPPLY SYSTEM FOR REGENERATIVE TRAINS

This paper proposes a pure electric brake that supplies the service brake in normal operation solely in an electrical mode down to a complete stop. This reduces mechanical wear of the brake linings and realizes much better riding comfort with easier and exacter braking maneuver. This full usage of the regenerative braking mode is becoming popular in Japan. However, there are still problems to be solved before all related parties can enjoy the advantages of this technique; insufficient braking force at high speed due to the power limitation, squeezing of braking force at excessive line voltage at the pantograph of the braking train, and giving up the regeneration when no other trains simultaneously absorb the regenerated power. Combination of regenerative and rheostatic braks has, therefore, been introduced on some lines, which have long and steep slopes. This paper deals with the countermeasures in the power feeding system by introducing equipment for absorbing regenerated power effectively. Several case studies show the effectiveness of the wayside power-absorbing components for the full usage of the regenerative electric brakes.

Microprocessor-Based Universal Thyristor Switch and its Application to a PWM Inverter for Traction

Digital control of static power converters such as pulsewidth modulated (PWM) inverter realizes the precise waveform control which copes with interference problems by selective elimination of harmful harmonics not only in load voltage but also in source current. Moreover, software control has a great advantage in allowing such a flexible system design or adaptable modification of characteristics by only memory change or program revision with the hardware intact. In this paper, a novel system configuration technique using microprocessors is proposed.

STATE VARIABLE ESTIMATION AND ACTIVE STEERING CONTROL OF INDEPENDENTLY MOTORED WHEELS FOR ON-BOARD TURNOUT

Very short headway train operation is required for realizing better urban transport services in recent years. The very short train operation at a turnout enables various novel methods of train operation, such as nonstop operation of certain coaches while the rest part of the train stops after decoupling in its approach to a station, and more efficient usage of coaches by frequent coupling/decoupling vehicles at many junctions. This type of operation has been restricted by uncertainty of existing wayside turnout devices. The paper briefly explains the advantage of the on-board switching from the systems point of view. Steering through a control of independently motored wheels is one of the most feasible technical alternatives for realizing the function of the on-board turnout. The study analyzed dynamics of a single axis boggie with independently motored wheels and examined the active steering control through simulations. The controller was designed based on Kesslers canonical form. One can estimate these variables by measuring the lateral displacement and applying a Luenberger state observer to the control system. The extended observer can be used also to estimate the lateral force.

RAIL SERVICE ON TRIPLE-TRACK LINES: PROPOSAL AND BENEFITS

Commuters traveling to schools and offices in the morning in Japan congest trains, and this has become a serious social problem. On the other hand, the cost to purchase land for a new track is high. This paper proposes an efficient railway operation by using a triple-track line, which has greater flexibility and provides better services than a double-track line--in fact, almost up to the level of a quadruple-track line--with novel train scheduling adapting demand structure. The significance of the railway service on a triple-track line has been verified based on the calculations of waiting time, boarding time of passengers, and costs of facilities for the operations.

On-Board Turnout in a Flexible Operation of Rail-Guided Transport System

Abstract A novel concept of an on-board turnout has been proposed for highly frequent vehicle service for a public urban transport. The advantages of the proposed system have been verified by comparing typical headway. Possible device configurations have been classified. The control of steering guidance force has been analyzed: The theoretical feasibility of the active control of independently motored wheels has been verified through simulations of wheelset dynamics.

The Microprocessor in Railway Control Systems

Application of microprocessors in railway systems has been as promising as is seen in other fields. After mentioning the sound applications to monitoring on-board equipments, traffic control, passenger information systems, control at marshalling yards, etc., state-of-the-art technologies in this field will be described; on (i) energy saving operation of intercity trains, (ii) interference-free ac motor drive system and (iii) microcomputerised realisation of fail-safe vital functions of signalling system. Functions of (i) and (ii) would not have been realised without using microprocessors and that of (iii) has been thought realisable only by using non-electronic fale-safe devices such as gravity-operated electromagnetic relays. Sections 1.3 and 2.3 are authored by Dr.Okumura and the rest by Dr.Sone.