A Small Magnetic Pre-Stress Based Piezoelectric Diaphragm Generator Induced by Hyperbaric Air

The piezoelectric generator with magnetic has been researched in many different fields. The magnetic is used as power assisting device which can promoted the performance of the piezoelectric generator. This paper presents a novel method that using the small magnetic force to adjust the electromechanical conversion efficiency of piezoelectric circular diaphragm when the hyperbaric air acts on it. The small magnetic force induced pre-stress acted on the center of the piezoelectric circular diaphragm can adjust the surface charge distribution by changing the displacement of the diaphragm. The theoretical analysis and simulated research show that the repulsive force increases the output power, while the attractive force decreases the output power. The experiment results show that the maximum output voltage and peak power across the 0.6 MΩ resistors are 72.8 V and 2.02 mW, respectively. The maximum peak power of the generator is promoted 13.5%, while the magnetic induced pre-stress is only about 0.6% of the hyperbaric air load. Therefore, the magnetic induced pre-stressing technique is an effective method to improve the efficiency and generated power in this type of piezoelectric generator.