A novel vibration energy harvesting system integrated with an inertial pendulum for zero-energy sensor applications in freight trains

With the development of the global economy, the demand for freight trains continues to rise, and the safety and maintenance of freight trains are essential. Therefore, sensors used for onboard monitoring of freight trains are vital components. However, the lack of onboard energy sources on freight trains makes the self-powering of sensors an urgent problem. In this paper, a novel renewable vibration energy harvesting system (VEHS) has been designed to provide electricity to sensors in freight train monitoring systems. The proposed VEHS mainly consists of three components: an energy input module, a motion transformation module, and an energy conversion module. The energy input module is composed of an inertial pendulum and a mass block. The movement transformation module integrates a novel and compact mechanical rectifier mechanism. The energy conversion module includes generators and energy storage devices. The wheel-rail coupled vibration is transformed into mechanical reciprocating rotation via the energy input module, and then into unidirectional mechanical rotation via the motion transformation module. Finally, the energy conversion module converts that mechanical energy of unidirectional rotation into electrical energy, and stores this micro-energy in a capacitor after rectification and boosting. Based on multi-body dynamics software and Simulink, a dynamic model was established to evaluate the vibration response of the system under different axle load and speed. Experiments revealed that the peak output power and energy harvesting efficiency of the VEHS were 1.04 W and 68.29 %, respectively. The RMS value of output power reaches 102.4 mW. In addition, this paper studies the application of the proposed VEHS to the China-Europe Express train. The results show that the system can be used to self-supply energy for freight train monitoring systems.