RF Energy Harvesting for Batteryless and Maintenance-Free Condition Monitoring of Railway Tracks

Current railway track condition monitoring relies on inefficient human inspectors and expensive inspection vehicles, where high-frequency inspection is unreachable since these methods occupy the tracks. This paper proposes a battery-less railway monitoring system based on RF energy harvesting to detect early defects on rail tracks. The key part of the system is a battery-less wireless sensor tag (BLWST) installed on railway tracks. The BLWST can harvest RF energy from a reader installed on the train, and precisely measure and wirelessly transmit vibration condition of tracks back to the reader. The proposed system eliminates the demands for cables and battery replacement, thus achieving low installation and maintenance cost. The high-frequency monitoring also provides a more reliable inspection than existing methods. The BLWST is based on the 3-stage Dickson voltage multiplier (DVM) and can be activated by a dedicated RF power source at a maximum distance of 2.3 meters. Experiments show that a maximum energy conversion efficiency of 25% and 500 working cycles per second are achieved. For demonstration, we construct a miniaturized railway system with the battery-less prototype and exhibit a reliable wireless power transfer and data communication.