Railway Traction Applications Research Articles

OWIM Drive Operated With Synchronized PWM With Odd-Non-Triplen and All-Triplen Pulse Numbers for Railway Traction Application

OWIM Drive Operated With Synchronized PWM With Odd-Non-Triplen and All-Triplen Pulse Numbers for Railway Traction Application

Review of Fault Diagnosis Methods for Induction Machines in Railway Traction Applications

Induction motors make up approximately 80% of the electric motors in the railway sector due to their robustness, high efficiency, and low maintenance cost. Nevertheless, these motors are subject to failures which can lead to costly downtime and service interruptions. In recent years, there has been a growing interest in developing fault diagnosis systems for railway traction motors using advanced non-invasive detection and data analysis techniques. Implementing these methods in railway applications can prove challenging due to variable speed and low-load operating conditions, as well as the use of inverter-fed motor drives. This comprehensive review paper summarizes general methods of fault diagnosis for induction machines. It details the faults seen in induction motors, the most relevant signals measured for fault detection, the signal processing techniques for fault extraction as well as some classification algorithms for diagnosis purposes. By giving the advantages and drawbacks of each technique, it helps select the appropriate method that could address the challenges of railway applications.

Life-cycle energy demand comparison of medium voltage Silicon IGBT and Silicon Carbide MOSFET power semiconductor modules in railway traction applications

Power semiconductors process roughly 70 % of global energy, with a higher percentage expected as worldwide transport electrification, renewables and wide-band-gap (WBG) semiconductors are implemented, significantly affecting global energy savings. This manuscript evaluates the cumulative energy demand (CED) encompassing the manufacture and use-phase in a railway traction application of silicon (Si) and silicon carbide (SiC) power semiconductor modules. Realistic manufacturing data from a power semiconductor fab has been considered for 3.3 kV/450 A state-of-the-art Si and SiC LinPak modules. SiC devices presented around 2.6 – 3.8× higher CED per area than Si devices in the manufacturing phase. However, due to the considerably smaller SiC chip area per ampere required, a 1.1 – 1.6× lower grey energy than Si technology is estimated. For the first time, such analysis is based on specialized power semiconductor fab data for both technologies and provides a baseline for the life cycle energy assessment of power electronics systems. Besides, the use-phase energy losses were evaluated for a realistic railway application, considering an operational lifetime of 30 years. The module manufacturing energy is negligible compared to the use-phase stage. Furthermore, the SiC technology presented an estimated energy-saving potential of 24 MWh/lifetime per module compared to the Si device.

A Simple Model Predictive Instantaneous Current Control for Single-Phase PWM Converters in Stationary Reference Frame

The traditional proportional–integral (PI) based current control for single-phase pulsewidth-modulation (PWM) converters in railway traction applications either has a steady-state error or a poor dynamic response. Deadbeat instantaneous current control (ICC) cannot eliminate the steady-state error due to approximation errors of the linear extrapolation. Compared with PI-based direct current control, continuous-control-set (CCS) model predictive control (MPC) implemented in a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d-q</i> frame offers better performance, but its dynamic response is still slower than ICC. To solve these problems, a simple model predictive (MP) ICC scheme for single-phase PWM converters is proposed in this article. The optimal modulation function is calculated in the stationary reference frame by the CCS-MPC principle without <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</i> -axis current estimation and reference frame transformation. The proposed MP-ICC scheme can keep the fast dynamic response characteristics of ICC and achieve zero steady-state error. In addition, it has the advantages of low current harmonics and low computational complexity. The influence of the inductance parameter mismatch on the current loop is analyzed in detail, and a phasor-method-based inductance parameter online estimation is developed. This solution can be executed during the idle time of the digital processor without making the control delay longer. Finally, a comprehensive experimental comparison with four existing current control schemes is conducted to verify the feasibility and effectiveness of the proposed scheme.

Analysis on characteristic of 3.3‐kV full SiC device and railway traction converter design

With the rapid development of wide-band gap semiconductor chip and package technologies, the voltage class of commercial silicon carbide (SiC) device is gradually improved. This paper concentrates on the latest 3.3-kV full SiC-based metal oxide semiconductor field-effect transistor (MOSFET) device and its application in railway traction. First, compared with the Si-based insulated-gate bipolar transistor (IGBT), the SiC-based MOSFET shows lower switching loss but weaker short-circuit capacity. Second, in the railway traction application, the SiC-based MOSFET with high switching frequency could reduce the inverter loss, the harmonic loss and the noise of traction motor. Third, a well-designed filter is necessary between the inverter and the motor to prevent the motor from terminal overvoltage and insulation problem, which are resulted from long cable and high dv/dt. Finally, a full-SiC railway traction inverter prototype is built and tested, and shows obvious advantages on miniaturization and lightweight.

Complex Current Regulator Design at Low Switching Frequency for Railway Traction Applications

Complex Current Regulator Design at Low Switching Frequency for Railway Traction Applications

Extended Overmodulation Operation of Space Vector PWM for Traction Motor Control at Low Switching Frequency

There are several benefits of fully utilization of DC link voltage in railway traction applications in terms of increasing inverter output voltage, satisfying power-torque demand and component sizing. To meet traction system requirements; mostly space vector pulse width modulation (SVPWM) is preferred since it has lower harmonic contents and larger voltage reservoir than the others such as sinusoidal PWM (SPWM). Despite extended linear range of SVPWM, it may not be sufficient for traction systems due to high power requirements and low ratio of switching frequency to inverter output frequency. To overcome this problem, an algorithm having functional in the overmodulation range of SVPWM up to square wave modulation and applicable at low sampling, switching frequencies is proposed. Proposed method has ability of soft transition to overmodulation area and covers continuously all the section. Also, calculation of modulation signals is independent from sampling period. The detailed design method is given to calculate modulation signals to be compared with carrier wave in two different overmodulation sections and implemented. Implementations are used in practical experiments to verify the effectivity of proposed method. Moreover, practical experiments to ensure stability of the method are conducted with high powered traction motor in low switching frequency.

Resonating Power Decoupling Using Multifunctional Bidirectional DC/DC Converter in Hybrid Railway Traction Application

For the single-phase high-power railway traction system, the inevitable second-order resonating power has become a critical issue to the traction system. In this article, a power-decoupling solution is proposed to replace the conventional passive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance filter by utilizing the buck-type bidirectional dc/dc converter (BBDC) of hybrid electric multiple units, which is designed to power the train in nonelectrified routes using the on-board battery. By considering both the current ripples in the battery mode and the power decoupling in the catenary mode, the corresponding parameter design process of the BBDC is presented. Based on the power coupling phenomenon and the spectrum characteristic of the BBDC, a direct resonance control method is proposed to decouple the low-order resonating power. Simulations and experiments are carried out to validate the effectiveness of the new proposal. The results demonstrate that the proposal is almost the same as using the conventional passive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance filter for power decoupling in both steady and dynamic operation scenarios.

Beat‐less algorithm based on dual‐frequency compensation in railway traction applications

AbstractThe beat phenomenon can be a critical issue in railway traction applications. This paper proposes a dual‐frequency compensation (DFC) method for the beat‐less algorithm to shift the spectrum of the beat voltages to a higher‐frequency region. Two variables for frequency compensation are derived by mathematical calculations based on the single‐frequency compensation (SFC) method. The applicability and superiority of the DFC method are analyzed. It is proposed that the DFC method can be a transition between the modulation index compensation (MIC) method and the SFC method, so the beat phenomenon can be greatly suppressed in the full speed range. The implementation of the DFC method is proposed to guide how to generate the two variables. The experimental verification is carried out on the StarSim hardware‐in‐loop platform, and the results demonstrate that the DFC method is more effective compared with the SFC method for beat phenomenon suppression. It also shows the modulation index with the DFC method is higher than that with the MIC method.

Fully FPGA‐based implementation of a modified control strategy for power electronic transformer in railway traction applications

AbstractDue to its several advantages (especially low volume and weight), power electronic transformer has gained notable attraction in railway applications. The main focus of this work is devoted to development a fully filed programmable gate array (FPGA)‐based control platform for power electronic transformer in the aforementioned application. Due to the parallel processing of FPGAs that results in a faster control algorithm execution, reliable operation (which is of major importance in traction applications) is guaranteed. For this purpose, an input series output parallel power electronic transformer structure is built, and various considerations for reliable and stable operation of the power electronic transformer in traction applications, such as safe start‐up and bidirectional power flow, along with the required control and pulse generation schemes, have been designed and implemented in a Xilinx FPGA control platform. Moreover, a modified control algorithm is proposed for controlling the power electronic transformer in a simple and more reliable manner. This control scheme is developed based on the output voltage of the DC–DC–LLC resonant converter, and can effectively control the sum of rectifier DC‐link voltages and track the input sine reference current, with a lower number of required sensors. Finally, the effectiveness of the proposal has been tested from various aspects by experimental tests.

DC-Link-Fluctuation-Resistant Predictive Torque Control for Railway Traction Permanent Magnet Synchronous Motor in the Six-Step Operation

In railway traction applications, the six-step operation of traction inverters is frequently applied at high speed due to the limitation of switching frequency of the converter which is installed in very limited space on the train. Meanwhile, without hardware filters installed, fluctuation components of dc-link voltage will emerge due to the input power ripple introduced by the single-phase rectifier, and can cause significant current and torque ripple in the motor. In this article, a direct torque control scheme for permanent magnet synchronous motor in a six-step operation is proposed to suppress the dc-link voltage fluctuation-induced current and torque ripple without extra hardware. It adjusts the duration of voltage space vectors according to the predicted dc-link voltage waveform six times per fundamental cycle, and minimizes the error between output torque and reference torque at the end of each time. Experimental results on an interior permanent magnet synchronous motor demonstrate that the proposed control can more effectively suppress current and torque ripple than state-of-the-art controls and achieve torque control with high dynamics and accuracy.

Control Strategies for Induction Motors in Railway Traction Applications

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.

Using the Five-Level NPC Inverter to Improve the FOC Control of the Asynchronous Machine

&lt;span lang="EN-US"&gt;Many researches have been dedicated to develop the induction motor drive control strategy used on the railway traction applications. In this paper we propose to investigate and to improve the electric locomotives by using a Field Oriented Control (FOC) strategy of induction motor drive. This induction motor can be powered by a five-stage neutral point inverter controlled by sinusoidal pulse width modulation (SPWM) due to good quality for output voltage and The use of fast switches. Both conventional and improved locomotives are simulated in Matlab/Simulink and compared in open loop conditions and closed loop conditions using IP controller, in term of torque response, current harmonic distortions and rotor speed response.&lt;/span&gt;

Input Filter for a Power Electronics Transformer in a Railway Traction Application

The need for lighter and smaller railway traction drives and recent advances in power semiconductor technology have resulted in a new energy conversion paradigm, one without the classical heavy and bulky line-frequency transformer. Several multilevel topologies have been introduced over the past years, all having in common the use of medium-frequency (MF) energy conversion to reduce the weight and volume of the magnetic components. This paper is concerned with the design of the input filter for an MF traction converter, focusing on a solution that minimizes the filter's overall mass. Two filter topologies are investigated, namely a single-pole filter (inductor) and a passively damped $LCL$ filter. The paper first describes the requirements to be fulfilled, establishes the spectrum to consider for the design, and proposes a method to determine the initial parameters of the filter's components. The results show that an $LCL$ -type filter achieves considerable weight savings in comparison to the single-pole solution.

Contribution of Bayesian Network to The prediction of the Reliability of IGBT Module Used in Railway Applications

One of the main issues in railway traction applications is the control of critical electronic components reliability. Insulated Gate Bipolar Transistors (IGBT) modules are part of these components. In their operating environment, they are subjected to high stresses due to severe conditions of use of the train. The increase of requirements in terms of reliability and safety impose to be able to assess these dependability measures. This paper introduces a methodological framework for predicting reliability of IGBT based on an innovative and structured Bayesian approach. An application study with real data has been finally carried out.

Validation of a modified direct-self control strategy for PMSM in railway-traction applications

This paper proposes and validates a modified direct-self-control (M-DSC) as a new control strategy option for permanent-magnet synchronous machine (PMSM) in railway traction applications. Taking into account all the specific requirements of the application and in order to stand-out its traction application capacity, a detailed analysis of the torque optimization technique (MTPA) and machine start-up capacity with low switching frequency have also been presented. Moreover, in order to achieve a robust control, two online permanent-magnet flux estimation techniques have been implemented. Experimental results, obtained from a 100-kW test bench, have demonstrated that the M-DSC control strategy fulfills all the railway-traction requirements: especially its very good dynamic performance. Therefore, this control can be a feasible alternative in PMSMs for railway traction applications.

Design of IPMSM Rotor Shape for Magnet Eddy-Current Loss Reduction

In this paper, an interior permanent magnet (PM) synchronous motor (IPMSM) with concentrated windings was designed for railway traction applications. This IPMSM was analyzed using a 2-D FEM. The results showed that the designed IPMSM has a significant PM eddy-current loss. For more accurate calculation, a 3-D FEM analysis was carried out. Further, the PM eddy-current loss was reduced without critical torque reduction by changing the position of the magnets at the rotor. Finally, frequency analysis of air-gap magnetic flux density waveforms was carried out to investigate the effect of magnet placement on the eddy-current loss.

State Observer-Based Sensor Fault Detection and Isolation, and Fault Tolerant Control of a Single-Phase PWM Rectifier for Electric Railway Traction

This paper presents an easy and a robust sensor fault detection and isolation (FDI) and fault tolerant control (FTC) of a single phase PWM rectifier for electrical railway traction application. Catenary current sensor and dc link voltage sensor failures are considered. The FDI method is based on observers and residual generation. The different FDI algorithm steps allow a good detection and isolation of the sensor fault and identify the faulty sensor. The reconfiguration strategy consists of two steps with open loop control and closed loop control working. Simulation results are presented to illustrate the good performance of the FTC procedure. Experimental results are also presented to show the effectiveness of the proposed FDI and FTC algorithms and good performances of the rectifier after the reconfiguration.

철도차량용 스위치드 릴럭턴스 전동기의 설계 및 속도제어에 관한 연구

3차원 유한요소법을 이용하여 엔드코일 효과를 고려한 SRM의 자계해석을 수행하였다. 고정자 극 형상에 따른 자계특성의 비교를 통하여 제안된 형상에서 자계특성이 향상됨을 확인하였다. 해석한 자계특성을 적용하여 철도부하에 대한 PI 제어기와 슬라이딩모드 제어기의 속도제어를 수행하였다. 속도 제어 시뮬레이션은 Matlab-Simulink를 사용하여 구현되었으며 부하 가변 조건에서 슬라이딩모드 제어기가 PI 제어기에 비해 더 우수한 과도응답 및 정상상태응답을 나타냄을 확인하였다. In this paper, a magnetic analysis of SRM(Switched Reluctance Motor) using 3d finite element method considering end-coil effect is presented. SRM models with different stator pole shapes are taken into consideration for the analysis of magnetic characteristics. It is observed that a stator pole shape model having a pole shoe depth is the most suitable one for railway traction application because it gives an improved inductance and torque characteristic. For a speed control of SRM, the PI and sliding mode controllers are applied to designed SRM with magnetic characteristic data obtained from the magnetic analysis. The simulations are carried out using Matlab-Simulink and the control performance is analyzed. By employing the sliding mode controller, the transient response as well as the steady-state error are much improved under a load variation of railway resistance under operation.

Development and Control of an Integrated and Distributed Inverter for a Fault Tolerant Five-Phase Switched Reluctance Traction Drive

A concept of an integrated and distributed inverter for switched reluctance machines is introduced. The application at hand is an outer-rotor direct drive designed for railway traction applications. A five-phase switched reluctance machine was developed and is used to demonstrate the function of the integrated and distributed inverter. The distribution is achieved by supplying each phase coil with its own modular inverter. Each inverter module is placed evenly around the end of the stator stack next to its dedicated coil. This increases the redundancy of the drive significantly. The likelihood of phase-to-phase faults is reduced, because no overlapping end-turns are necessary. Also, the integration of machine and inverter is simplified, because the semiconductors can be evenly distributed around the machine. The concept reduces the amount of terminals between drive and vehicle to communication, power supply, and cooling, independent of the number of machine phases. With the integrated and distributed inverter new control strategies can be developed to influence machine vibration and radiated noise. In this paper, the design of the prototype, the direct torque control of the five-phase machine, and the behavior in the case of a fault inside a module is analyzed.