Development of Urban Electric Bus Drivetrain

The development of the drivetrain for a new series of urban electric buses is presented in the paper. The traction and design properties of several drive variants are compared. The efficiency of the drive was tested using simulation calculations of the vehicle rides based on data from real bus lines in Prague. The results of the design work and simulation calculations are presented in the paper

Summary of the Modern Wheel Slip Controller Principles

Railway traction vehicles need to transfer high tractive effort from wheels to rails. The task is complicated because the maximum transferable force continuously changes during the train run, and the change can lead to the high wheels slip velocity or slippage. The effects are undesirable and must be prevented if it is possible or at least limited by slip controllers. There have been several slip controllers developed based on different principles with different degree of complexity and efficiency. The paper summarises principles of the slip control methods and brings their overview with the simulation of their behaviour

Development of numerical and experimental tools for the simulation of train braking operations

L'abstract è presente nell'allegato / the abstract is in the attachmen

PSO Based EKF Wheel-rail Adhesion Estimation

An ideal traction and braking system not only ensures ride comfort and transportation safety but also attracts significant cost benefits through reduction of damaging processes in wheel-rail and optimum on-time operation. In order to overcome the problem of the wheel slip/slide at the wheel-rail contact surface, detection of adhesion and its changes has high importance and scientifically challenging, because adhesion is influenced by different factors. However, critical information this detection provides is applicable not only in the control of trains to avoid undesirable wear of the wheels/track but also the safety compromise of rail operations. The adhesion level between the wheel and rail cannot be measured directly but the friction on the rail surface can be measured using measurement techniques. Estimation of wheel-rail adhesion conditions during railway operations can characterize the braking and traction control system. This paper presents the particle swarm optimization (PSO) based Extended Kalman Filter (EKF) to estimate adhesion force. The main limitation in applying EKF to estimate states and parameters is that its optimality is critically dependent on the proper choice of the state and measurement noise covariance matrices. In order to overcome the mentioned difficulty, a new approach based on the use of the tuned EKF is proposed to estimate induction motor (as a main part of the train moving system) parameters. This approach consists of two steps: In the first step the covariance matrices are optimized by PSO and then, their values will be introduced in the estimation loop.

EXTENDED KALMAN FILTER DESIGN FOR RAILWAY TRACTION MOTOR

Monitoring the adhesion force between a railway wheel and a rail surface is very essential in maintaining the high acceleration and braking performance of railway vehicles. Due to the difficulties encountered in direct measurement of friction coefficient, creepage and adhesion force, state observers are used as indirect estimation methods. This paper proposes an effective estimation method, which exploits railway traction motor behaviour to give an assistance for realizing wheel slip and adhesion control in order to be used in railway applications. This method plays an active role in optimizing the use of the existing adhesion and reducing wheel wear by decreasing high creep values. With this method, adhesion force can be indirectly estimated by measuring stator currents, and angular speed of the AC traction motor and using dynamic relationships based on the extended Kalman filter (EKF) simulation model. The re-adhesion controller can be designed to regulate the motor torque command according to the maximum available adhesion depending on the estimated results. To test the proposed method, simulations were performed under different friction coefficients.   

Traction asynchronous electric drive of mine electric locomotivesimulation model structure improvement

The article discusses the solution to the problem of underground railway transport slipping in dynamic modes, which occurs when there is a significant difference in the speeds of the driving and driven pairs of wheels. The state of the rail surfaces largely determines the coefficient of adhesion, therefore, using a mathematical model, the condition for the dependence of the magnitude of slipping and tractive effort is selected. For effective acceleration and deceleration of an electric locomotive, it is necessary to control the coefficient of adhesion at a certain level. A simulation model of rolling stock has been created, which for the first time takes into account a mechanical system with distributed parameters. In the structural diagram of the automatic control system of traction electric drives with frequency regulation, such factors as the volume of goods being moved, rolling friction, slope (rise) levels and the state of the rail track are taken into account. The simulation results show the features of the movement and stops of the freight train not only by the diagrams of speed and forces in the modes of acceleration-deceleration and uniform movement, but also the positions of the plungers and tractive forces on the couplings of the electric locomotive and all trolleys involved in the movement of goods. The practical application of the proposed method lies in the possibility of starting a heavily laden train from its place on the ascent section in conditions of insufficient adhesion coefficient with contaminated roads

Harmonic current sideband indicators (HCSBIs) for broken bar detection and diagnostics in cage induction motors

Induction motor bar breakages have been increasingly studied in the last decades because of economic interests in developing techniques that permit on-line, non-invasive, early detection of motor faults in power plants. This work is specifically focused on broken bar detection and fault severity assessment in three phase power cage motors fed by non-sinusoidal voltage sources. In this work some new fault indicators for rotor bar breakages detection in squirrel cage induction motors are proposed, mathematically developed and experimentally proved. They are based on the sidebands of phase current upper harmonics, and they are well suited especially for converter-fed induction motors. The ratios I(7-2s)f/I5f and I(5+2s)f/I7f , I(13-2s)f/I11f and I(11+2s)f/I13f are examples of such new indicators, and they are not dependent on load torque and drive inertia, as classical indicators do. Their frequency-dependence has been also examined both theoretically and experimentally, and it was found less remarkable with respect to other indicators. Moreover, their values increase linearly with the quantity of consecutive broken bars, almost for not too much advanced faults; on 4-poles motors they were found quietly like the per-unit number of broken bars (ratio on total bar number). An original formulation is presented for motor mathematical modeling, based on the Generalized Symmetrical Components Theory, for sidebands amplitude computation. A complete motor model (involving all the elementary machine electrical circuits, as stator belts and rotor mesh loops) has been used for computer simulations; the same model was then transformed by using some complex Fortescue’s matrices to obtain a steady-state linear solution, solvable for stator and rotor currents, in healthy and faulty conditions. By exploiting the model, the formal definition of a set of new broken bar indicators was finally obtained. Machine simulations carried out by running the complete numerical model confirmed the accuracy of the model, and the theoretical previsions. Experimental work was performed by using a square-wave inverter-fed motor with an appositely prepared cage, for easy testing with increasing number of broken bars and without motor dismounting. Moreover, extensive experimentation was carried out on three industrial motors with different power and poles number, with increasing load, frequency and fault gravity for methodology validation. Finally, the ideas exposed in this work led to a patent application, owned by the University of Rome “Sapienza”

Control laws of a salient pole synchronous machine in a mine electric locomotive

Relevance. The need to find effective control of a traction synchronous motor with permanent magnets in a mining electric locomotive under conditions of limitation of current and voltage supplied to its windings from an autonomous power source. Aim. To choose a control law that ensures an increase in a mine electric locomotive mileage on one battery charge with its speed growth. Object. Control laws of a salient pole synchronous motor with permanent magnets of a mining electric locomotive; laws of current control along the transverse axis; control by the current minimum and control by minimizing the reactive power of a salient pole synchronous machine. Methods. Analysis of the state of the electric machine with different formation of control of an electric drive in the mine electric locomotive. The main limiting indicators of an electric machine with voltage and current limitation were considered. For each control law, the results of mathematical modeling are shown in graphical and tabular form. Results. The analysis of the current control law along the transverse axis demonstrates a significant increase in reactive power with increasing load. In an hourly mode of operation, the reactive power exceeds the active power spent on the movement of the electric locomotive. When limiting the current and voltage, the minimum current control allows you to increase the electromagnetic torque by 12.7% in hourly operation. The maximum engine speed is increased by 13%. The maximum power spent on the electric locomotive movement increases by 33%. Reactive power is reduced by 29%. With reactive power minimization, despite the decrease in the electromagnetic torque in the hourly mode of operation by 4.8%, the maximum possible engine speed increases by 53%, the power spent on the electric locomotive movement increases by 50%

Running Dynamics of Rail Vehicles

The investigation of rail vehicle running dynamics plays an important role in the more than 200 year development of railway vehicles and infrastructure. Currently, there are a number of new requirements for rail transport associated with the reduced environmental impact, energy consumption and wear, whilst increasing train speed and passenger comfort. Therefore, the running dynamics of rail vehicles is still a research topic that requires improved simulation tools and experimental procedures. The book focuses on the current research topics in railway vehicles running dynamics. Special attention is given to high-speed railway transport, acoustic and vibrational impact of railway transport to the surroundings, optimization of energy supply systems for railway transport, traction drives optimization and wear of wheels and rails