Urban Rail Vehicle Research Articles

New energy urban rail vehicle hybrid energy storage control system

Abstract With the increasing demand for urban transportation and the gradual strengthening of environmental protection awareness, new energy urban rail transportation has gradually become the future trend of urban development. The hybrid energy storage system is one of the key technologies to achieve the goals of energy saving and emission reduction of new urban rail vehicles, improving operation efficiency and comfort. In the traction stage of urban rail vehicles, the energy storage unit composed of lithium batteries and supercapacitors is jointly supplied with the power grid. In the braking stage, the energy storage unit composed of lithium batteries and supercapacitors is a common way for urban rail vehicles to recover energy. This study validates the efficacy of employing fuzzy control methodology to enhance the performance of the energy storage system. The experimental results show that the fuzzy control method can better balance the load distribution between lithium batteries and supercapacitors, thus extending their service life and improving the overall system performance. Based on the SOC energy management strategy of supercapacitors, urban rail vehicle power is allocated to supercapacitors and lithium-ion batteries via a low-pass filter. System power is adjusted based on supercapacitor SOC, determining capacitor charging/discharging states and suppressing system output power.

Friction and Wear Behavior of SiCp/Al Brake Disk Sliding Against Semimetallic Brake Pad under the Braking Condition of Urban Rail Vehicles

Due to their low density and exceptional wear resistance, SiCp/Al composites have great potential for brake materials used in trains. In this study, a newly developed SiCp/Al brake disk was fabricated by a powder metallurgy method. The friction and wear behavior of SiCp/Al brakes were investigated under extensive velocity ranges (40–220 km/h) according to the scale conversion rules. It is found that the matching tribocouple exhibits low wear loss, a reliable friction factor, and high heat resistance. The friction film maintains its continuity and stability at high braking speeds and temperatures, effectively protecting the surface of SiCp/Al composite materials from damage, minimizing wear, and stabilizing the friction coefficient. The excellent reliability of the lightweight SiCp/Al brake disk performance confirms its high technical feasibility to replace heavy iron and steel brake disks in urban rail vehicles that normally travel at 220 km/h.

Online Stator Interturn Fault Detection Using Hilbert Transform and Neural Network for Traction Motors of Urban Rail Vehicles

Online Stator Interturn Fault Detection Using Hilbert Transform and Neural Network for Traction Motors of Urban Rail Vehicles

Research on the traction characteristic evaluation of urban rail vehicles based on entropy weight TOPSIS

This paper aims to investigate the influence of different speed at the end of the constant power section of the traction characteristic curve (TCC) on the vehicle dynamic performance and evaluate the TCC. A dynamics co-simulation model is developed in SIMPACK and MATLAB for dynamic analysis of the urban rail vehicle (URV) under different traction characteristics. Then it is used to investigate how acceleration distance and vehicle dynamic performance varies with the speed at the end of the constant power section of the TCC under different starting torques. Moreover, the entropy weight TOPSIS method which is widely used to solve the multi-objective decision-making problem is chosen to evaluate the traction characteristics based on various dynamic performance indexes over 25 test sections and acceleration distance. The results show that under traction conditions, the starting torque has effects on the lateral and vertical accelerations of car body, lateral and vertical wheel-rail contact forces, derailment coefficient and wheel unloading factor. The higher the torque, the greater the value of each index, that means the poorer the vehicle ride characteristics and running safety. For a given starting torque, the dynamic performance indexes increase with the increase of the speed at the end of the constant power section from 50 km/h to 80 km/h during the vehicle speed-up process. The maximum growth rate of the lateral and vertical accelerations of car body, lateral and vertical wheel-rail contact forces are 17%, 8%, 8% and 2%, respectively, when the speed at the end of the constant power section increases from 50 km/h to 80 km/h. Last, the comprehensive evaluation of traction characteristics using entropy-weight TOPSIS method reveals when the starting torque is 800 [Formula: see text], 1000 [Formula: see text], 1200 [Formula: see text] and 1400 [Formula: see text], the corresponding optimal speed at the end of the constant power section is 80 km/h, 80 km/h, 70 km/h and 50 km/h, respectively. The result of the study can provide theoretical support for traction characteristic design and traction control for URVs.

Evaluation on LED lighting driving power supply for urban rail vehicles based on adaptive PID algorithm

LED (Light Emitting Diode) lighting has the characteristics of efficiency, environmental protection, energy conservation, and so on. It is more and more widely used in the lighting system of urban rail vehicles. The research on the LED lighting system of rail vehicles has important practical significance. As the core of the LED lighting system of rail vehicles, the LED control system of urban rail vehicles is the key to ensure the stable operation of the entire LED lighting system. The lighting environment of urban rail vehicles needs LED lighting system with good power stability, long life of drive chip, high feedback accuracy, fast processing speed, intelligent algorithm efficiency and other characteristics to ensure continuous operation, and also should have strong anti-interference ability and excellent static performance. However, conventional lighting systems not only have low life, but also have poor stability. Therefore, this paper studied the uniqueness and functional module analysis of LED driving power supply by analyzing the causes and disadvantages of LED lighting, and finally optimized the design of LED lighting control system by using the adaptive PID (Proportional Integral Differential) algorithm. Through comparison, the brightness acquisition quality of LED lighting control system was 21.2 % higher than that of traditional lighting control system, and the lighting control effect was 18 % higher than that of traditional lighting control system. In short, the selection of LED lighting driving power affects the lighting effect of rail vehicles.

Impacts of On-board Energy Storage Devices on the Energy Consumption of Train Operations

Urban rail transit systems consume significant electrical power, with traction accounting for 50% of the total energy (from China Urban Rail Transit Association [1]). As operational mileage and vehicle counts rise, so does energy consumption, underscoring the importance of vehicular energy conservation. This study evaluates the impact of on-board energy storage devices on train energy efficiency. Using operational data from Changsha Metro Line 5 and incorporating literature reviews and simulations, the energy-saving potential was assessed. Integrating these storage devices with vehicle energy monitoring systems shows promising potential for energy conservation and operational efficiency. This research presents a viable strategy to reduce energy consumption in urban rail vehicles, enhancing system competitiveness.

Dynamics modeling of urban rail vehicle axle-box bearings with roller defect considering time-varying impact

Accurately simulating the vibration response of the axle-box bearing with a localized defect on the roller can guide the proposal of several health condition estimation methods. However, there is still a lack of discussion and analysis on the detailed motion process of the roller defect passing through the inner/outer race. For filling this gap, a roller defect model considering time-varying impact is proposed and applied to the vehicle–track coupling system considering axle-box bearings. In addition to the Hertz contact force due to the relative displacement between the roller and race, time-varying impact excitation is designed according to the law of the conservation of energy. At first, an onsite test and an experimental test are implemented to validate the accuracy of the roller defect model and the vehicle–track coupling model, respectively. Then, the effect of the roller defect on the vibration characteristics of the components in the vehicle system is investigated. Finally, the influence of the defect size and vehicle speed on the vibration response of the axle-box bearing is studied, and the change rule of the time-varying impact is also researched with the defect size. Besides, the axle-box vibration response is simulated under variable vehicle speeds, and order tracking technique is applied to analyze the simulated result.

An investigation on dynamic vibration characteristics of urban rail vehicle axle-box bearings in the presence of rail welds

The operation condition of axle-box bearings strongly affects the running safety of vehicles. However, the presence of rail welds can impact the wheel-rail interaction system, causing changes in the dynamic response of axle-box bearings and furtherly affecting their health condition. Despite this, there is still a lack of discussion and analysis on the effect of rail welds on dynamic characteristics of axle-box bearings. Therefore, a vehicle-track coupling dynamics model is developed. Besides the rigid vehicle model, flexible track model and wheel-rail contact model, the axle-box bearing model and flexible wheelset model are considered. Among them, the axle-box bearing model accounts for the motion of the roller and cage decentralized into multiple segments. Using modal superposition method, the flexible deformation of the wheelset is calculated and overlapped with its rigid displacement for the flexible wheelset model. The performance of the model is verified through theoretical analysis and field tests. It is crucial to consider the wheelset as flexible in the presence of rail welds and its effects are also researched. Moreover, the effect of the rail weld geometry on the wheel-rail separation is studied, and the consequence caused by rail welds on the bearing damage is discussed under different vehicle speeds.

Rigorous investigation into the identification of malfunctions in the air conditioning and refrigeration systems of urban rail vehicles

Rigorous investigation into the identification of malfunctions in the air conditioning and refrigeration systems of urban rail vehicles

A Service-Driven Routing Algorithm for Ad Hoc Networks in Urban Rail Transit

Due to increased traffic pressure, traditional urban rail vehicle–ground communication systems are no longer able to meet the increasing communication requirements. In this paper, ad hoc networks are applied to urban rail transit vehicle–ground communication systems to improve link reliability and reduce transmission delay. In the proposed network, a service-driven routing algorithm is proposed, which considers the distance factor for cluster head selection and optimizes the routing transmission delay by service priority and congestion level. An auxiliary node-based routing maintenance mechanism is also proposed to avoid the problem of frequent breakage of communication links due to the high-speed movement of trains. Through the simulation, the proposed algorithm can effectively reduce the packet loss rate, end-to-end delay, and routing overhead of vehicle–ground communication compared with the traditional routing algorithm, which is more conducive to meeting the next generation of urban rail transit vehicle–ground communication requirements.

Online Noninvasive Technique for Condition Monitoring of Cooling System in Urban Rail Vehicles

The open self-ventilated cooling system is an important component to dissipate heat in urban rail vehicles. While after long term operation, the cooling system will deteriorate, which ultimately affects the reliable operation of traction converter. In this paper, we propose a method to monitor the health status of cooling system in urban rail vehicles using the temperature response curve of negative temperature coefficient (NTC) thermistor built in IGBT module. Back Propagation Neural Network (BPNN) is employed to predict the reference curve of healthy state under different working conditions and Discrete Fréchet Distance (DFD) algorithm is applied to achieve the difference comparison. The proposed approach considers the dynamic response process and is suitable for online monitoring. Advantages of the proposed approach include no need to install additional measurement circuit and to heat the module to thermal equilibrium. Moreover, this method enables the concurrent monitoring of multiple components in the cooling system. Simulation analysis and experimental tests are performed to verify the accuracy and effectiveness.

Cooperation of active steering control of wheelsets with subsystems of an autonomous urban rail vehicle

The paper presents the motivations for the application of actively controlled elements in the running gear of a rail vehicle and the challenges that need to be addressed before deploying vehicles with actively controlled elements in real operation. Furthermore, the paper presents the design of an active element concept and its control for steering the axles of an urban rail vehicle to improve the vehicle’s passage through small radius curves. The design takes into account the fundamental issues of cost and safety of the application of active elements, which are addressed in the presented control design by using data from autonomous driving subsystems such as the environmental database or the anti-collision system.

Data-driven urban rail vehicle critical parts maintenance system based on cloud-edge collaboration

In view of the limitations of traditional maintenance methods for rail vehicles, this study proposes a data-driven maintenance system for critical parts of rail vehicles based on a cloud-side collaborative framework. Currently, there are several major issues with the maintenance of critical parts of rail vehicles, including long maintenance cycles, difficult troubleshooting, high maintenance costs, low maintenance efficiency, irregularities in data management, and a low level of informatization. To address these problems, a cloud-edge collaboration approach is adopted. The maintenance information of the vehicles is synchronized and exchanged in real-time with the cloud data center. Sensor and Internet of Things (IoT) technologies are used to collect real-time operational and status data of rail vehicles. The data is then analyzed and modelled in the cloud data center. The system achieves fault prediction and remaining useful life prediction for key components of the rail vehicles by applying machine learning algorithms. The experimental results demonstrate that compared to traditional maintenance methods, the system enables more effective troubleshooting and remaining useful life prediction of critical components of the vehicles. It improves maintenance efficiency and safety while also offering practical application value.

Dynamics modelling and vibration characteristics of urban rail vehicle axle-box bearings with the cage crack

The cage crack changes the structural stiffness on different components, and therefore affects its relative contact forces. Furthermore, the crack may cause the fault characteristics on the urban rail vehicle axle-box bearing. Despite all this, there is still a lack of discussion and summary on the dynamics modelling and vibration characteristics analysis of axle-box bearings with the cage crack. For filling this gap, two cage crack models are proposed, which are respectively constructed when the crack generates in the cage bridge or arm. Then, these models are coupled to the axle-box bearing model in a vehicle-track coupling model. Thereinto, the friction force and the motion of rollers are considered, and the cage is decentralized into several segments for facilitating the study of the force between adjacent cage segments. At last, the dynamic characteristics of axle-box bearings with the cage crack are investigated, and the changes in contact forces due to the cage crack are also analyzed. This study can provide valuable information for axle-box bearing condition tracking and monitoring.

Dynamic Analysis of Slab Track with Crack Considering Rail Corrugation

To investigate the dynamic response of ballastless slab track with crack in the rail corrugation area under the load of urban rail vehicle, this study establishes a vertical coupling dynamic model of the vehicle-rail-slab track, considering crack and rail corrugation. The exact closed-form solution of the vibration mode of the Euler Bernoulli beam with crack is introduced. Furthermore, a finite element model of the slab track is developed, and the vertical dynamic model's fastening force is applied to the slab track at the rail corrugation frequency to calculate the surface compressive stress of the slab track. The results indicate that, under rail corrugation conditions of varying magnitudes, the presence of crack induces higher vertical acceleration amplitudes in the slab track at low frequencies. As the wave depth increases, the acceleration of the slab track at the crack gradually intensifies. Moreover, with an increasing wavelength, the corresponding frequency to the acceleration amplitude of the slab track at the crack gradually decreases. Notably, when the wave depth is 0.2 mm and the wavelength is 50 mm, the axle load transfer rate exhibits the greatest increase. These research findings offer valuable insights for the maintenance of urban rail transit slab track systems.

A Dynamic Addressing Hybrid Routing Mechanism Based on Static Configuration in Urban Rail Transit Ad Hoc Network

With the rapid development of urban rail transit, the traditional urban rail wireless network based on fixed infrastructure is not in a position to meet the increasingly complex communication demand. At the same time, Ad Hoc network, as a special wireless mobile network, is developing rapidly. Applying this self-organized networking architecture to the urban rail vehicle–ground communication network can overcome the problems existing in the traditional urban rail communication system. The routing protocols that can achieve low delay and highly reliable data transmission are important in the urban rail transit scenario. Therefore, combined with the wireless Ad Hoc network and the characteristics of the urban rail transit scenario, this paper proposes a dynamic addressing hybrid routing mechanism based on static configuration. Using an improved AODV routing discovery algorithm and then writing the routing table into the router in advance for static configuration not only reduces network overhead but also prolongs the network’s lifetime. It also saves the delay of routing discovery. Then, the cluster head node dynamically monitors the link status, dynamically finds the path when the link needs to be replaced, and selects different update paths according to different types of communication services. Finally, each algorithm’s network performance parameters, like the routing discovery overhead, residual link lifetime, packet delivery rate, throughput, and end-to-end delay, are analyzed and compared.

Kinematic running resistance of an urban rail vehicle undercarriage: a study of the impact of wheel design

Urban railway vehicles are important means of transport in towns and cities due to their high capacity, power source, and low running resistance, which make them efficient for operation. Although these properties are considered advantages, there is still room for improvement in their operational efficiency. The main objective of this article is to investigate the impact of railway wheel design on the level of kinematic running resistance, which is expressed as the amount of mechanical energy losses during the interaction of wheels with rails. This research focuses on simulation computations of two variants of wheel design schemes: the traditional design scheme (TKS) and a perspective design scheme (PKS) characterized by a rotating flange independently of the wheel tread surface. Two undercarriage multibody models have been created, one with TKS and one with PKS, and simulation computations have been performed for running speeds of 10 km/h, 20 km/h, 30 km/h, and 40 km/h on track models in curves with radii of 20, 50, 100, 150, 200, and 250 m. The evaluated indicators affecting the level of mechanical energy losses were creep forces, slip velocities, and average power. The most important findings of this study are that the PKS design scheme resulted in lower values of all assessed parameters.

Upgrading Of Two Position Anti-skid Valve For Braking System Of Urban Rail Transit Vehicles

Based on the structural principle of the existing two-position anti-skid valve for urban rail vehicles, the valve has been modified to increase the pressure maintaining position based on the original only brake position and release position, so as to upgrade to the three-position anti-skid valve. As the pressure-maintaining position is added, the maximum braking force shall be kept as far as possible under the premise of anti-skid control of the train, so as to shorten the braking distance and ensure driving safety.

Skidding characteristics of urban rail vehicle axle-box bearings considering surface waviness on races

As one of the core transmission components, axle-box bearings have been widely applied in urban rail vehicles and played a crucial role in their safe and stable operation. No matter in the starting and stopping stage or stable operation stage of the vehicle, the skidding phenomenon in axle-box bearings exists and impacts their own dynamic characteristics. Furthermore, as one of the main shape errors of the bearing surface, waviness may cause fluctuations for skidding characteristics of axle-box bearings. This study investigates the skidding dynamic analysis of axle-box bearings, taking into account race surface waviness. Firstly, a dynamics model for double-row cylindrical roller bearings is established, considering the cage flexibility and friction forces between different components. Then, this model is coupled with a three-dimension vehicle–track model, allowing for more precise dynamic simulation of axle-box bearings under actual running conditions. Furthermore, an excitation related to race surface waviness is added to the coupling model through time-varying displacement and contact stiffness. At last, the influence of race surface waviness on skidding characteristics of axle-box bearings is analyzed. The effectiveness of the proposed model is validated through theoretical analysis and field tests. Simulation results demonstrate that race surface waviness can impact the cage and roller slip ratio of axle-box bearings. Overall, this study provides valuable insights into the skidding dynamic analysis of axle-box bearings, highlighting the importance of considering race surface waviness in designing and maintaining axle-box bearings.

Research on Wheel Out-of-round Fault Diagnosis Based on Vibration Data Images

Background: The wheel out-of-round fault of urban rail vehicles has a very important impact on the safe operation of urban rail trains. Therefore, it is of great significance to achieve an accurate diagnosis of the wheel out-of-round fault of trains. Objective: The purpose of this paper is to summarize the diagnosis methods of the wheel out-of-round fault, and propose a new diagnosis method based on vibration data images, which can effectively identify the wheel out-of-round fault. Methods: The one-dimensional vibration signal is converted into a two-dimensional texture matrix. The Statistical Geometrical Features (SGF) method extracts the feature information of the twodimensional gray image and combines it with a support vector machine for training and recognition to achieve the fault diagnosis of the wheel out-of-roundness. Results: The feasibility and accuracy of the method are verified by simulation and experimental signal analysis, respectively. The experimental results show that the overall recognition accuracy of the model simulation data and the two-wheel experimental bench data exceeds 91%, exhibiting significantly high fault identification accuracy. Conclusion: In this paper, a wheel out-of-round fault diagnosis model based on vibration data images has been established by analyzing the vertical dynamic signal of the axle box, which has the advantages of fast recognition in combination with two-dimensional grey-scale images, no signal preprocessing, and high recognition accuracy. It provides a new method for monitoring and diagnosing wheel out-of-round faults in urban rail vehicles.