Abstract: In order to improve the reliability and effective bandwidth of rotary piezoelectric generators,a piezoelectric energy harvester with amplitude limit is proposed and the characteristic of different spring stiffness、excitation distance、cam lift and lift angle was evaluated through theoretical analysis, simulations, and experiments. Research results show that exciting the piezoelectric by moving cam, a flat voltage amplitude-frequency characteristic curve without significant peaks can be obtained. Under other parameters given, the effective speed bandwidth increases as the lift decreases but the maximum output voltage also decreases; The cam angle increases (30°-45°) has no affect to the maximum output voltage, but it can broaden the speed bandwidth effectively; Reducing the excitation distance can increase the excitation force, thereby increasing the horizontal amplitude of the cam and the reliability of the generator can be effectively improved by properly matching the stiffness of the rebound spring and the buffer spring. When buffer spring's stiffness is 50 N/m,rebound spring's stiffness is 20 N/m, cam lift is 2 mm,lift angle is 40°,excitation distance is 8 mm, there is a loading resistance 70 kΩ to maximize the output power, and the output power reaches 10.88 mW when the rotary speed is 392 r/min and the power generation performance of the energy harvester can be improved.

Key words: piezoelectric energy harvester, magnet excitation, cam, amplitude limit, spring stiffness