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 article proposes a batteryless railway monitoring system based on radio-frequency (RF) energy harvesting to detect early defects on rail tracks. The key part of the system is a batteryless 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 the 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 costs. The high-frequency monitoring also provides a more reliable inspection than the 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 m. 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 batteryless prototype and exhibit a reliable wireless power transfer and data communication.