Electromechanical Suspension-based Energy Harvesting Systems for Railroad Applications

• Main Author: Nagode, Clement Michel Jean
• Other Authors: Mechanical Engineering
• Format: Others
• Published: Virginia Tech 2014
• Subjects: Energy Harvesting; Railroad; Suspension; Electromagnetic; Truck; Energy Recovery
• Online Access: http://hdl.handle.net/10919/50611

Currently, in the railroad industry, the lack of electrical sources in freight cars is a problem that has yet to find practical solutions. Although the locomotive generates electricity to power the traction motors and all the equipment required to operate the train, the electrical power cannot, in a practical manner, be carried out along the length of the train, leaving freight cars unpowered. While this has not been a major issue in the past, there is a strong interest in equipping modern cars with a myriad of devices intended to improve safety, operational efficiency, or health monitoring, using devices such as GPS, active RFID tags, and accelerometers. The implementation of such devices, however, is hindered by the unavailability of electricity. Although ideas such as Timken\'s generator roller bearing or solar panels exist, the railroads have been slow in adopting them for different reasons, including cost, difficulty of implementation, or limited capabilities.<br /><br />The focus of this research is on the development of vibration-based electromechanical energy harvesting systems that would provide electrical power in a freight car. With size and shape similar to conventional shock absorbers, these devices are designed to be placed in parallel with the suspension elements, possibly inside the coil spring, thereby maximizing unutilized space. When the train is in motion, the suspension will accommodate the imperfections of the track, and its relative velocity is used as the input for the harvester, which converts the mechanical energy to useful electrical energy.<br /><br />Beyond developing energy harvesters for freight railcar primary suspensions, this study explores track wayside and miniature systems that can be deployed for applications other than railcars. The trackside systems can be used in places where electrical energy is not readily available, but where, however, there is a need for it. The miniature systems are useful for applications such as bicycle energy.<br /><br />Beyond the design and development of the harvesters, an extensive amount of laboratory testing was conducted to evaluate both the amount of electrical power that can be obtained and the reliability of the components when subjected to repeated vibration cycles. Laboratory tests, totaling more than two million cycles, proved that all the components of the harvester can satisfactorily survive the conditions to which they are subjected in the field. The test results also indicate that the harvesters are capable of generating up to 50 Watts at 22 Vrms, using a 10-Ohm resistor with sine wave inputs, and over 30 Watts at peak with replicated suspension displacements, making them suitable to directly power onboard instruments or to trickle charge a battery.<br /> === Ph. D.