A Ball-Impact Piezoelectric Converter Wrapped by Copper Coils

This letter presents a composite piezoelectric and electromagnetic converter with a ball-impact structure. It is composed of a magnet ball enclosed among two piezoelectric diaphragms, which arranged in a copper coils wrapped cube. A theoretical model is proposed to simplify the motion of the ball in a cycle as three steps and to estimate output voltages. Experiments were conducted to measure output voltages of both piezoelectric and electromagnetic units. The observed experimental results are in good agreement with the theoretical ones.