A frequency-up-conversion electromagnetic energy harvester for long-term infrastructure anomaly monitoring

Self-sustaining energy solutions for manhole covers are critical to reducing battery dependency and lowering the maintenance demand in urban infrastructure. This paper presents a novel smart manhole cover (SMC) incorporating an array of compact electromagnetic generators (EMGs) that efficiently convert ambient mechanical vibrations into continuous rotational motion via a unique frequency-up-conversion mechanism. The innovative mechanical design, which integrates a vibration-to-rotation converter, a toothed clutch, and an energy storage/release module, enables continuous rotational acceleration under impulsive loads, as validated by a coupled electromechanical model. Multiphysics simulations confirm the structural durability and optimized power output of the device. This optimized design enables the compact EMG (Φ7 cm × 3 cm) to achieve a remarkable peak power density of 41.6 mW/cm³ and an average power of 1.04 W. A fully self-powered manhole cover anomaly monitoring system (MC-AMS) is developed and demonstrated, capable of real-time triaxial acceleration detection and multi-state perception. Under 1 Hz excitation, a single EMG simultaneously powers the system and charges a 15-mAh battery, achieving a 30% charge in 230 seconds and enabling a total continuous operation time of one hour. Furthermore, a 60-day field deployment, with acceleration data collected at regular intervals, confirms the long-term reliability and practical viability of this self-powered system. The SMC in this work provides dual benefits of energy autonomy and peak shaving for smart cities.