An Improved Torque and Current Pulsation Suppression Method for Railway Traction Drives Under Fluctuating DC-Link Voltage (original) (raw)

Ac-DC Converters Topology in Traction Application for DC Motor Drive

2015

Separately excited dc motors fed by sequentially operated multistage converters are commonly used in mainline traction. The drive performance can be greatly improved by operating the multistage half controlled converters. Drive of a shunting locomotive of 25kV ac traction consists of a half-controlled converter feeding dc series traction motors. It suffers from two important limitations. First, at low output voltages the converter power factor is low. Secondly, the source current with square wave shape is rich in harmonics. In case of suburban and main line trains power rating is large, consequently, the adverse effects of the poor power factor, harmonics and harmonic disturbances on the supply network and telecommunication lines are unacceptable. To overcome these limitations multistage converters, which are operated with sequence control, are used to feed armatures of traction motors. The two halfcontrolled converters arrangementimproves power factor and reduction in reactive powe...

Control Strategies for Induction Motors in Railway Traction Applications

Energies, 2020

This paper analyzes control strategies for induction motors in railway applications. The paper will focus on drives operating with a low switching to fundamental frequency ratio and in the overmodulation region or six-step operation, as these are the most challenging cases. Modulation methods, efficient modes of operation of the drive and the implications for its dynamic performance, and machine design will also be discussed. Extensive simulation results, as well as experimental results, obtained from a railway traction drive, are provided.

A Novel Approach for Controlling the Electric Drives Used in Electric Trains

Acta Polytechnica Hungarica, 2014

Nowadays, the DC motors have been replaced by induction motors in most of the industrial applications. Substantially, Induction motors are single speed, but they can produce high power density in a wide range of speed by applying new drive controllers based on constant V/f, DTC and vector control theory. Electric motors control is mainly accomplished by power electronic drives based on control schemes like constant v/f. However, the challenge of torque generation with fast time response and high accuracy was met by using the controllers based on vector control and DTC. In applications like electric train, generation of torque with rapid time response is so vital. As an example, in Anti skid-Anti slid system, the generated torque should vary between zero and the desirable value quickly to prevent the electric train from slip and the wheels from skidding on the rail. However, the accuracy of the torque magnitude due to its high value is not an important issue and most of the time, errors up to 3 percents in the generated torque is acceptable. In this paper, the control systems used in constant v/f drives are modified in order to generate torque with fast time response and acceptable accuracy. Control systems stability is an essential concern in electric drives and is arisen from the complexities in the controller's process and the time delays. In the proposed system, by simplification of the drive controllers, the instability problem of the control units is eliminated which in turn reduces the calculation time delays and results in torque generation with appropriate time response. Furthermore, the overall cost of the drive system is reduced considerably.

Novel Motor-Kinetic-Energy-Based Power Pulsation Buffer Concept for Single-Phase-Input Electrolytic-Capacitor-Less Motor-Integrated Inverter System

Electronics, 2022

The motor integration of singe-phase-supplied Variable-Speed Drives (VSDs) is prevented by the significant volume, short lifetime, and operating temperature limit of the electrolytic capacitors required to buffer the pulsating power grid. The DC-link energy storage requirement is eliminated by using the kinetic energy of the motor as a buffer. The proposed concept is called the Motor-Integrated Power Pulsation Buffer (MPPB), and a control technique and structure are detailed that meet the requirements for nominal and faulted operation with a simple reconfiguration of existing controller blocks. A 7.5 KW, motor-integrated hardware demonstrator validated the proposed MPPB concept and loss models for a scroll compressor drive used in auxiliary railway applications. The MPPB drive with a front-end CISPR 11/Class A EMI filter, PFC rectifier stage, and output-side inverter stage achieved a power density of 0.91 KW L−1 (15 W in−3). The grid-to-motor-shaft efficiency exceeded 90% for all lo...

An active power filter method to improve the line current spectrum of PWM locomotive rectifiers with load unbalance

2007

Locomotives in heavy haul and high speed passenger operations represent several megawatts of electrical load. Single phase power collected by a pantograph is typically rectified by multiple PWM converters. The converter switching instants are phased to ensure ripple current cancellation, assuming that the converter loads are balanced. Partial failures may result in unbalanced operation with reduced cancellation. The resulting harmonics may adversely impact the signalling systems and/or result in over voltage effects due to resonance in the overhead supply system. This paper examines a 4MW locomotive with three rectifier modules and a device switching frequency of900Hz. This results in a 5400Hz ripple frequency in the mains current. Ideal balanced operation of converters is compared to an unbalanced operation case. Unbalanced cases include rectifier failures, inverter failures and changes in the relative balance of power delivered to each axle of the locomotive. This paper will consi...

Analysis of Control Methods for the Traction Drive of an Alternating Current Electric Locomotive

Symmetry, 2022

The analysis of operating conditions of traction drives of electric locomotives with asynchronous traction motors has been carried out. It was found that during operation in the output converter of an asynchronous motor, defects may occur, which leads to asymmetric modes of its operation. Models of a traction drive of an electric locomotive with asynchronous motors with scalar and vector control of the output converter are proposed, taking into account asymmetric operating modes. As a result of the simulation, the starting characteristics of the traction drive were obtained for various control methods both in normal and emergency modes of the drive. For the drive-in emergency mode, the following cases were investigated: the balance of the converter output voltages and the turn-to-turn circuit of 10% of phase A winding of the motor stator; imbalance of the output voltages of the inverter and an intact motor; imbalance of the output voltages of the converter and interturn short circui...

Synthesis of the Current Controller of the Vector Control System for Asynchronous Traction Drive of Electric Locomotives

Energies, 2022

This paper deals with the analysis of the operating conditions of traction drives of the electric locomotives with asynchronous traction motors. The process of change of the catenary system voltage was found to have a stochastic character. The method of current controller synthesis based on the Wiener–Hopf equation was proposed to enable efficient performance of the traction drive control system under the condition of the stochastic nature of the catenary system voltage and the presence of interferences, when measuring the stator current values of the tractor motor. Performance simulation of the proposed current controller and the current controller used in the existing vector control systems of the traction drives used in the electric locomotives was implemented. The results of the performance simulation of the proposed current controller were compared with the performance of the current controller in existing vector control systems of the traction drives. The results are applicabl...

Scalar Variable Speed Motor Control for Traction Systems with Torque and Field Orientation Filter

IFIP Advances in Information and Communication Technology, 2016

Scalar traction control systems can be used in trains, trams and electrical vehicles equipped with induction motors. To increase the versatility and efficiency of such systems compared to conventional solutions, they must enable dynamic links to different types of power grids, i.e., be supplied by multi-frequency and multi-voltage power sources. Behind these solutions, there are control systems based on vectorial controllers. In order to set systems with the above features, in this work it is intended to build a scalar traction control system, in which the speed is controlled via a scalar controller. The system controls the motor speed and also the position of the rotor and stator fields. Furthermore, it allows to clearly setting the operation conditions, i.e., avoiding situations that would change from braking to traction and vice-versa due to operational and/or functional disturbances. To achieve the required speed reference follow up, the proposed solution includes a torque and field orientation filter.

A Review on Various Converters Used In Dc and Ac Locomotives

Power electronics, already formerly being a leading light for growth of traction vehicles .The aim of this paper is to group and review these electronic devices, in order to set up the current state of the art and trends of the technology in Electric Railways. This paper presents a brief overview of all types of locomotives with its traction motors specifications, types of rectifiers and inverters used for conversion of power to traction motor and various types of converters used nowadays in ER's. Based on already existing information, this paper presents the overview on converters using in locomotives. It is apparent that for most electrically-fed railways, the use of modern power converters is attractive. Where the electric railways are high consumers of energy, the railway gradients are significant, and the public grids feeding the railways are weak, the use of converters would be technically desirable, if not necessary for electrification. This paper presents about the regenerative braking in locomotives and EMI problems occurring in Electric Railways.