A Multi‐Degree‐of‐Freedom Piezoelectric Kinetic Energy Harvester for Self‐Powered Wireless Sensors in Electric Buses

Harvesting energy from the surrounding environment represents a viable method for developing self‐powered systems and realizing that vehicles' low‐power sensors are self‐powered. Nevertheless, existing energy harvesting devices exhibit limitations in their capacity to capture kinetic energy across a broad spectrum of motion. To overcome this limitation, a multi‐degree‐of‐freedom piezoelectric energy harvester has been developed, comprising three modules: motion conversion, energy transformation, and power storage. The motion conversion module utilizes a connecting rod and sliding bearing mechanism to transform complex three‐dimensional motions of swing body into simplified two‐dimensional movements of sliding mass. The energy transformation module utilizes piezoelectric elements to convert mechanical energy into electrical energy, which is then rectified and stored in capacitors by the power storage module. Experimental results demonstrate the system's capability to generate a maximum average output power of 758 μW. Capacitor charging tests show that 100, 330, and 470 μF capacitors can be charged to 1 V in 20, 32, and 50 s, respectively. Real‐world vehicle tests confirm the practical applicability of this harvester, providing valuable insights for developing self‐powered wireless sensor systems.