AC Traction Motors Research Articles

An Advanced Antislip Control Algorithm for Locomotives Under Complex Friction Conditions

Abstract The locomotive wheelsets configured with high-power AC traction motors are very prone to slip under poor friction conditions, which usually impair traction/braking efficiency. To avoid the adverse consequence caused by the conspicuous slipping behaviors of wheels, the antislip control modules are consequently equipped on high-power locomotives. This paper presents an advanced antislip control algorithm for heavy-haul locomotives traveling by complex wheel/rail friction conditions. The proposed antislip control model is implemented in a three-dimensional (3D) heavy-haul train-track coupled dynamics model, in which the real-time estimation of wheel/rail adhesion conditions and relevant optimization adjustment of control threshold values are considered. The wheel/rail dynamic interactions of the heavy-haul locomotive under traction/braking conditions and multifarious friction conditions are investigated. The control effects of the antislip controllers with changeable and constant threshold values are compared. It is shown that the traction/braking loads and friction conditions have a significant effect on wheel/rail interactions. The optimal traction/braking efficiency can be realized by adopting the antislip controller with alterable threshold values.

Traction inverter with integrated charger: practical realisation and experimental study

This article presents some practical designs for combining control functions of AC traction motor and high voltage on-board vehicle battery pack charge using single hardware components and common power circuit. Basic charger and traction inverter integration circuit designs as well as conditions necessary for keeping their power equivalent are described in the article. Based on these circuit designs, the new traction inverter with integrated charger design is suggested. This design has the advantage of high-power density, optimal weight and size ratio and relatively simple control system realisation. The suggested design is recreated in a voltage converter experimental sample. The study results of the created design basic functional characteristics are provided in the article. Traction inverter with integrated charger practical realisation results can be used in the advanced vehicle (electric vehicles, hybrid electric vehicles) development and construction as well as in autonomous power supply systems.

Loss Analysis of Propulsion System on an Electric Railway

Electric Railway (KRL) is a train that is based on eletrification system. The electrification system in the KRL supplies electrical energy to the train locomotive and several other carriage units, so the train can run. Electrical energy can be either AC or DC source. There are two electrical systems to support the performance of KRL, propulsion system and auxiliary system. The propulsion system is a driving system and than the auxiliary system is the system that handles the electrical load on KRL. In this research, discuss about the loss of propulsion system on KRL LAA Electric DC, AC Traction Motor. The propulsion system consists of several components, such as pantograph, circuit breaker, capacitor filter, IGBT VVVF inverters and AC traction motors. The component has different losses and different efficiencies. There are five test conditions for AC traction voltage inputs of 160.5V, 321V, 493.9V, 635V and 645V. By calculating using equations, from the five test conditions it can be seen that the propulsion system has the lowest power loss with the highest efficiency at the input voltage of AC 635V traction motors, which obtained the power loss of inverter VVVF IGBT 41.996kW with the efficiency 90.67% and the power loss of AC traction motor 18.219kW with the efficiency 91.45%.

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.

A Mechatronic Approach for the Detection of Wheel Slip/Slide and Antislip Control of Locomotive with AC Traction Motors

This paper presents a mechatronic approach for the detection of wheel slip/slide and antislip control of locomotive with ac traction motors, to enable an optimal use of adhesion in poor contact conditions. The proposed technique explores the variations in wheelset dynamic properties caused by condition changes at the wheel-rail contact and detects slip conditions from measurement of train speed with internal optical encoder of the wheelset axle indirectly. The modeling of a typical traction system, consisting of an induction traction motor (with associated power inverter and field-orientated control) connected to a wheelset via a gearbox, is introduced. The development of the slip detection and control scheme is presented, and the effectiveness of the proposed technique is demonstrated using computer simulations.

Modelling of track wear damage due to changes in friction conditions: A comparison between AC and DC electric drive locomotives

The locomotive traction motor electric dynamics and its impact on the rail and vehicle have not been investigated deeply in transient wheel–rail contact conditions. Such transient traction behaviour could be more significant to dynamic traction performance and track degradation (i.e. corrugation formation, fatigue, wear, etc.) than steady state behaviour. In order to study this, detailed numerical simulations are performed to investigate the locomotive multi-body dynamic response to a change in contact conditions with an AC and DC electrical traction motor respectively. In particular, creep response, locomotive vibration, and dynamic normal and tractional forces are determined using a developed full scale locomotive dynamics model. The model includes the detailed AC and DC motor dynamics. Further investigation has been undertaken to understand the wear caused during and after the change of friction conditions from dry to wet and wet to dry. The result shows the GT46Ace locomotive AC drive can achieve higher traction efficiency compared to the equivalent DC drive running under notch 8, especially in the wet condition. It is also demonstrated that the AC drive produces slightly lower wear on average than the DC drive after the transient. However, the transient dynamic oscillation of wear caused by the AC drive is significantly higher than the DC drive.

Operation analysis of AC traction motors in terms of electromagnetic torque capability on sustainable railway vehicles

Sustainable operation of electric railway systems represents a significant purpose nowadays in the development of high power and high speed locomotives and trains. At present, high speed electric vehicles mostly work with three-phase induction motors or three-phase synchronous motors as traction motors. The two electric machine types have different efficiencies at different operation points, and experience differences with respect to safety, speed and power, energy use and exergy efficiency. An important issue that correlates these aspects is the electromagnetic torque developed by an electric traction motor. In order to provide an overview of the technical performance of the operation of sustainable railway systems, a detailed analysis is carried out of the electromagnetic torque capability of AC electric motors utilized as traction motors in modern locomotives of high power and/or high speed. The results of this work may help in enhancing the main criteria for optimising the safe and sustainable operation of electric railway traction systems.

Impact of Parallel Operation of AC Traction Motors on Locomotive Performance

Presented paper deals with common problems of parallel operation of AC traction motors and presents some methods to investigate the basic impacts of the concept. A complex simulation model is introduced as well as results of simulations. Based on the results, a conclusion is made on locomotive performance impact.

Re-adhesion control for a railway single wheelset test rig based on the behaviour of the traction motor

A method for detecting wheel slip/slide and re-adhesion control of AC traction motors in railway applications is presented in this paper. This enables a better utilisation of available adhesion and could also reduce wheel wear by reducing high creep values. With this method, the wheel–rail (roller) creepage, creep force and friction coefficient can be indirectly detected and estimated by measuring the voltage, current and speed of the AC traction motor and using an extended Kalman filter. The re-adhesion controller is designed to regulate the motor torque command according to the maximum available adhesion based on the estimated results. Simulations under different friction coefficients are carried out to test the proposed method.

Starting Phenomena and Temperature-rise under vvvf Supply of Three-Phase Squirrel-Cage ac Traction Motor of Electric Locomotive

In three-phase squirrel-cage ac traction motor, temperature-rise calculation during variable-voltage and variable-frequency starting is of vital importance and has to be predicted and critically examined. Under voltage source inverter supply with PWM, the generation of harmonics by inverter supply reduces the output during starting due to higher harmonic losses, thereby reducing the starting tractive effort in kN on locomotive wheel. Stator and rotor temperature-rises during starting have been determined for average acceleration torque in segmental zone (calculated from variable acceleration) which have been presented in the paper with both copper and aluminium alloy rotor bars.

A mechatronic approach for effective wheel slip control in railway traction

This article proposes a radically new approach for the detection of wheel slip/slide and re-adhesion control of AC traction motors in railway applications, which provides an important alternative and advantageous technique in traction/braking control systems to maximize the use of adhesion in poor contact conditions. The proposed concept explores the variations in the wheelset dynamic properties caused by the condition changes at the wheel—rail contact, and detects and controls the slip conditions from the dynamic behaviour of a wheelset, indirectly. All the dynamic motions of rail wheelset, which are closely related to wheel—rail contact mechanics, are included in the study; the influence of contact conditions on the relevant modes is assessed, which is essential in the development of a mechatronic solution based on dynamic interactions. This is different from the more general approaches in many other studies on traction controls where the inclusion of only wheelset rotation and longitudinal motions are considered as sufficient. The development of the slip detection and re-adhesion control schemes is presented and comprehensive simulation results are produced to support the proposed idea.

ELECTRIC DRIVES OF TRACTION ROLLING STOCKS WITH AC MOTORS

The paper considers the variation of circuit design of the electric drives in traction rolling stocks when traditional DC electric machines are replaced with AC electric machines. Simplified circuit diagrams of the electric drives using electric machines of non‐commutator type are offered. Operational defects of DC traction engines are weighed against some positive characteristics of direct current series excitation in traction engines, determining their extensive use in the electric drives of traction rolling stocks. However, the rapid development of semiconductor devices, e.g. thyristors and IGBT transistors, led to the creation of a great variety of semiconductor inverters. This made it possible to develop an autonomous three‐phase power supply system for diesel locomotives and algorithms for the AC traction motors and to obtain engine characteristics matching the tractive force by using voltage frequency and current inverters. A mathematical justification of the engine torque and tractive force control as well as its particular characteristics is provided. The graphs demonstrating the particular ways of changing the electrical parameters of an asynchronous motor with a squirrel‐cage rotor are also presented.

The Rapid Transit System That Achieves Higher Performance with Lower Life-Cycle Costs

In the age of traction system made of inverter and ac traction motors, distributed traction system with pure electric brake of regenerative mode has been recognised very advantageous. This paper proposes a new system as the lowest life-cycle cost system for high performance rapid transit, a new architecture and optimum parameters of power feeding system, and a new running method of trains. In Japan, these components of this proposal, i.e. pure electric brake and various countermeasures of reducing loss of regeneration have been already popular but not as yet the new running method for better utilisation of the equipment and for lower life-cycle cost. One example of what are proposed in this paper will be made as Tsukuba Express, which is under construction as the most modern commuter railway in Greater Tokyo area.

C702 THE RAPID TRANSIT SYSTEM THAT ACHIEVES HIGHER PERFORMANCE WITH LOWER LIFE-CYCLE COSTS

In the age of traction system made of inverter and ac traction motors, distributed traction system with pure electric brake of regenerative mode has been recognised very advantageous. This paper proposes a new system as the lowest life-cycle cost system for high performance rapid transit, a new architecture and optimum parameters of power feeding system, and a new running method of trains. In Japan, these components of this proposal, i.e. pure electric brake and various countermeasures of reducing loss of regeneration have been already popular but not as yet the new running method for better utilisation of the equipment and for lower life-cycle cost. One example of what are proposed in this paper will be made as Tsukuba Express, which is under construction as the most modern commuter railway in Greater Tokyo area.

Electric railway traction. Part 1: Electric traction and DC traction motor drives

This series of tutorial articles explains the electrical and control engineering background in electric railways. The articles cover traction drives with DC and AC traction motors, electrification systems, and railway signalling and control systems. This first article covers the nature of the traction load, the requirements of the traction duty cycle and power electronic controlled traction drives using DC machines.

Consideration on high quality AC traction motor drives using PWM converters.

Consideration on high quality AC traction motor drives using PWM converters.