A hybrid railway traction system with fuel cells (FCs) and electric double layer-capacitors (EDLCs) is discussed in this paper. This system can save FC costs and absorb the regenerative energy. A method for designing FCs and EDLCs on the basis of the output power and capacitance, respectively, has not been reported, even though their design is one of the most important technical issues encountered in the design of hybrid railway vehicles. Such design method is presented along with a train load profile and an energy management strategy. The design results obtained using the proposed method are verified by performing numerical simulations of a running train. These results reveal that the proposed method for designing the EDLCs and FCs on the basis of the capacitance and power, respectively, and by using a method for controlling the EDLC voltage is sufficiently effective in designing efficient EDLCs and FCs of hybrid railway traction systems.

A DC-electrified railway system that is fed by diode rectifiers at a substation is unable to return the electric power to an AC grid. Accordingly, the braking cars have to restrict regenerative braking power when the power consumption of the powering cars is not sufficient. However, the characteristics of a DC-electrified railway system, including the powering cars, is not known, and a mathematical model for designing a controller has not been established yet. Hence, the object of this study is to obtain the mathematical model for an analytical design method of the regenerative braking control system. In the first part of this paper, the static characteristics of this system are presented to show the position of the equilibrium point. The linearization of this system at the equilibrium point is then performed to describe the dynamic characteristics of the system. An analytical design method is then proposed on the basis of these characteristics. The proposed design method is verified by experimental tests with a 1kW class miniature model, and numerical simulations.

Diesel engine lithium-ion battery hybrid vehicles are gaining attention because the energy consumption during their operation and exhaust emission can be reduced considerably. However, designing a reasonably accurate method for the engine power and battery energy has not yet been proposed, though the above mentioned type of traction system can help in realizing an environment-friendly railway vehicle. In this paper, a design method for the battery capacity (energy) and engine output is proposed in the case of a control strategy in which the sum of the kinetic energy of the vehicle and the battery energy is maintained constant. The proposed method is verified by the velocity/state of charge of the battery charts obtained in the experimental tests. The proposed design method can be used to develop the environment-friendly railway traction systems for non electrified lines.

A method for reducing motor torque in proportion to wheel slip is applied to an inverter-driven electric locomotive. The motor torque at wheel-slip speed is less than the torque at the maximum tangential force or the adhesion force. A novel anti-slip control method for seeking the maximum value of the tangential force between the wheel and rail is proposed in this paper. The characteristics of the proposed method are analyzed theoretically to design the torque reduction ratio and the rate of change of the pattern between the wheel-slip speed and motor current. In addition, experimental tests are also carried out to verify that the use of the proposed method increases the traction force of an electric locomotive driven by induction motors and inverters. The experimental test results obtained by using the proposed control method are compared with the experimental results obtained by using a conventional control method. The averaged operational current when using the proposed control method is 10% more than that when using the conventional control method.

This paper presents a simple and energy-saving method for controlling hybrid powered railway vehicles that run on rural non-electrified railway lines and have diesel engine and electrical double layer capacitors (EDLCs). The aim this study is to reduce both the fuel consumption and the capacitance of EDLCs. A basic idea proposed in this paper is that EDLCs supply and absorb the kinetic energy of the vehicle and the engine output compensates supply the energy loss with the vehicle running. Thus, the energy loss is not taken into consideration while expressing the EDLC voltage reference (equation 1); energy loss is considered when the engine is in operating mode. The proposed method is examined by performing numerical simulations for various values of engine operation time, load, and grade section. The results of this study reveal the relationship between the capacitance of the EDLCs and the fuel consumption. Using this proposed control methods, excessive charging of EDLCs can be avoided. The results of this study are expected to expedite the development of energy-saving railway vehicles for the non-electrified lines.<br>Finally, the results of this study increase the possibility of developing hybrid powered railway vehicles.

In this paper, we study a control method based on the virtual indirect circuit method for a single phase to three phase matrix converter (MC). The MC has a capacitor at the input side to compensate for the single phase input power fluctuation. We propose a method to determine the amplitude of the compensation capacitor voltage on the basis of the load power. The method is validated using a 1350W class single phase to three phase matrix converter system. In addition, restrictions on the modulation ratio of the input current and the compensation capacitor current are revealed, showing the limit of the output voltage according to the load power.

A linearization method is proposed for controlling the start-up operation of a rotating induction motor. The dynamics of this motor are deteriorated when the starting operation is carried out at high frequencies. In this method, the characteristics of the method are analyzed to reveal that the aforementioned problem is caused by the low equivalent gain of the induced voltage during the rotor flux establishment. A method to compensate for the angle of the rotor-flux-induced voltage vector is proposed to overcome this problem. The proposed method is experimentally verified by a test set, and the influence of changes in the rotor resistance is analyzed.

In this study, we examine the relationship between harmonic voltage injection, acoustic noise, and position estimation performance in a PMSM when a position-sensorless control method involving harmonic voltage injection is used at low speeds. Further, we propose a novel control method for voltage injection; this method can be used to reduce acoustic noise in the motor. The proposed control method is verified by performing numerical simulations and carrying out experiments using a 4-pole, 2-kW, 2100-rpm IPMSM (interior permanent-magnet synchronous motor).

This paper investigates starting procedure of rotation sensorless PMSM at coasting condition for railway vehicle traction. To realize the restarting, the initial rotor position and speed at restart are needed. The existing estimation algorithm of the initial position and speed can't be applied to railway vehicle traction because of the higher speed range and the longer current period. We propose novel estimation method of the initial speed. The estimation method is verified experimentally to ensure that it is feasible enough to be applied to the railway vehicle traction system.

In this paper, we study an optimal design for a hybrid power source railway vehicle as an alternative to diesel railway vehicles. The hybrid power source railway vehicle is assumed to be composed of the fuel cell and the electric double layer capacitor. We apply the multiobjective optimization based on the genetic algorithm for the vehicle design, aiming at reduction of both initial cost and energy consumption. The pareto optimal solutions are obtained using the multiobjective optimization.<br>First we develop a simulation model of the hybrid power source railway vehicle and its electric power control methods. Next we derive the pareto optimal solutions as a result of the multiobjective optimization. Finally, we categorize the pareto optimal solutions to some groups, which enables us to elucidate characteristics of the pareto optimal solutions. Consequently, using the multiobjective optimization approach we effectively comprehend the problem characteristics and can obtain the plural valuable solutions.

This paper describes the experimental results of a test to drive two induction motors through a VVVF inverter by 25kW class proton membrane type fuel cells (PEMFCs). The experiments are aimed at verifying the compatibility between the drive system for the railway vehicle traction and FCs. This paper describes test results of powering, powering-off procedure, and simulated slip-readhesion control test, respectively. Through the experiments, we obtained useful knowledge required in designing the fuel cell drive system.

The harmonics of the return current may interfere with the signaling current along with the rails. In this paper, we present the theoretical studies of the return current harmonics in the inverter-controlled DC electric railcar, aiming at contributing future work to improve the compatibility with the signaling current.<br>We theoretically derive sideband harmonics of the DC-link current. Then, in order to verify the theoretical study, we experimentally measure the harmonics and numerically simulate the harmonics. As a result, we concluded the theoretical DC-link current is enough accurate to be utilized for the future improvement of the inverter harmonics current.

The Pulse Generators or PGs are equipped to detect the rotor frequency of induction traction motors for the torque control in railway vehicle traction field. Eliminating PGs are preferable from the view points of increasing the reliability of the traction system, reduction of the both initial and maintenance cost and down-sizing induction traction motors. Expecting those merits, we have been studying to apply a sensor less control method to induction traction motor control. Prior to some reports of studies and tests to apply speed sensor-less strategy to railway vehicle traction, we lunched the ideas to apply the speed sensor-less control strategy and results of the studies and the tests. In this paper, we present the novel control method for railway vehicle traction and some results of theoretical study and tests.

This paper is aimed at providing the designing method of a permanent magnet synchronous motor (PMSM) control system for the high-speed and the single-phase AC powered Gauge Changing Train (GCT). The state-of-the-art electrical motive unit is equipped with downsized direct drive type PMSMs for the simplified gauge changeable truck. Due to the feeding the AC single phase power, we propose a beat-less control for PMSMs. We verify the development results of designing procedures by the experimental results of operation on a high-speed test line in Colorado, USA.

The permanent magnet synchronous motor (PMSM) is an efficient machine, which has found application over wide power and speed ranges. This paper presents the optimal rotor design of a PMSM for use on a railway vehicle. This design utilizes reluctance torque in order to develop higher torque at starting with low open circuit voltage at high speed.

We have been investigating to apply permanent magnet synchronous motors (PMSMs) to railway vehicle traction, because the efficiency of PMSMs are higher than that of induction motors and they are expected to enable the traction motor down sized. We have to consider peculiarity on the railway vehicle traction when we design the electrical constants of PMSMs. On this paper, we point out the particular points which we have to take into account on designing works and analyze how the constants of PMSMs affect the their performance. Through this study, we suggest how to design the constants and applied the method to assumed designing works to verify the method. We conclude that the suggested method is available for the designing of PMSMs’ constants and reluctance torque is essential to the performance PMSMs for railway vehicle traction purpose.

As battery spread more widely in recent years, we have to model its transient response precisely to grasp the whole characteristic of power source system in designing, for example, the efficient driving system of electric vehicle(EV). Up to this time, many methods are presented for battery modeling, but it is still difficult to obtain the exact characteristics of battery by them. In this paper, with this background, we propose a novel method to model the transient response of battery in view of the control engineering. In the proposed method, we measure the frequency-response of battery and introduce the concept of transfer function to decide the admittance value of battery. Finally we estimate the equivalent circuit of battery from the obtained admittance value. We also investigate the variation of circuit-constant values with the battery residual capacity.

The regenerative braking method has been employed in DC-fed electric railway vehicle traction system in order to reduce energy consumption. The load's power consuming is sometimes insufficient for the regenerated power, and it causes the input voltage of traction inverter rises. In such a case, the regenerative current is regulated to prevent the over voltage. However, in applying this regulation, especially to the permanent magnet synchronous motors (PMSM) traction system, a continuous oscillation of regenerative current is sometimes observed. Unfortunately, It deteriorates passengers' riding comfortability due to torque fluctuation.<br>On this paper, we analyze the phenomena of the oscillation of regenerative currents and suggest an anti-oscillation regenerative current regulation method based on the analyzing results. The detail is as follows.<br>(1) We construct a nonlinear time-varying model, which consists of the substation, power feeding system and the main traction circuit onboard and divide the nonlinear time-varying model into four linear time-invariant systems.<br>(2) Through the analysis with the models, we make it clear that the continuous oscillation is caused by the traditional regenerative braking control method<br>(3) Based on the analysis we suggest a novel anti-oscillation regenerative braking control method, whose effectiveness is proved through experiments.

DC electrified railway line voltage at pantograph often changes according to load condition of other electric vehicles. Vehicle propulsion system is disturbed by this line voltage change. For practical use it must be made clear how the permanent magnet synchronous motor control system for railway traction behaves at line voltage change. In this paper we try to analyze our proposed PMSM control system behavior under sudden change of DC line voltage through pole arrangement and numerical simulation and obtain technical knowledge under this phenomenon.

At high speed range in voltage source inverter (VSI) fed permanent magnet synchronous motor gap flux is weakened to limit terminal voltage for saving the capacity of VSI. In weakening flux operation of salient pole PMSM, d-axis current and qaxis current can't be decided deductively due to reluctance torque. To cope with this problem we propose feedback control of motor torque, which is calculated from current, voltage and motor speed. By this control method torque and terminal voltage can be determined without measuring them directly. In this paper, the proposed control system is discribed, the transient characteristic is studied and the test results. Lastly we show make it clear that our method is basically effective for railway vehicle traction.

We have been studying the aplication of permanent magnet synchronous motor (PMSM) for railway vehicle traction in order to reduce the weight and size of direct drive traction motor. As a part of this study establishing a current control system of PMSM suitable for railway vehicle traction should be investigated.<br>In this paper we discuss about designing method of current control system mentioned above and suggest a method which is available under the condition of railway vehicle traction, low switching frequency and long digital calculating period. Next we investigate how to decide current response time constant <i>T<sub>d</sub></i> and reach a conclusion that it is about 10ms is appropriate under some assumed condition. Then we checked this current control system for railway vehicle traction through experiments and studies of influence of parameter changing. Consequently we can recognize the current control system has satisfactory performance for railway vehicle traction.