ABSTRACT
In this paper, a piezoelectric electromagnetic composite energy harvester is studied. The device consists of a mechanical spring, upper and lower base, magnet coil, etc. The upper and lower bases are connected by struts and mechanical springs and secured by end caps. The device moves up and down under the vibration of the external environment. As the upper base moves downward, the circular excitation magnet moves downward, and the piezoelectric magnet is deformed under a non-contact magnetic force. Traditional energy harvesters have the problems of a single form of power generation and inefficient energy collection. This paper proposes a piezoelectric electromagnetic composite energy harvester to improve energy efficiency. Through theoretical analysis, the power generation trends of rectangular, circular, and electric coils are obtained. Simulation analysis yields the maximum displacement of the rectangular and circular piezoelectric sheets. The device uses piezoelectric power generation and electromagnetic power generation to achieve compound power generation, improve the output voltage and output power, and can provide power supply to more electronic components. By introducing the nonlinear magnetic action, the mechanical collision and wear of the piezoelectric elements during the work are avoided, so that the service life and service life of the equipment is extended. The experimental results show that the highest output voltage of the device is 13.28 V when the circular magnets mutually repel rectangular mass magnets and the tip magnet of the piezoelectric element is 0.6 mm from the sleeve. The external resistance is 1000 Ω, and the maximum power output of the device is 5.5 mW.
ABSTRACT
This paper describes a rotary piezoelectric wind energy harvester with bilateral excitation (B-RPWEH) that improves power generation performance. The power generating unit in the current piezoelectric cantilever wind energy harvester was primarily subjected to a periodic force in a single direction. The B-RPWEH adopted a reasonable bilateral magnet arrangement, thus avoiding the drawbacks of limited piezoelectric cantilever beam deformation and unstable power generation due to unidirectional excitation force. The factors affecting the power generation were theoretically analyzed, and the natural frequency and excitation force of the piezoelectric cantilever have been simulated and analyzed. A comprehensive experimental research method was used to investigate the output performance. The B-RPWEH reaches a maximum output voltage of 20.48 Vpp when the piezoelectric sheet is fixed at an angle of 30°, the Savonius turbine number is 3, and the magnet diameter is 8 mm. By adjusting the fixed angle of the piezoelectric sheet, the number of Savonius wind turbine blades, and the magnet diameter, the maximum voltage is increased by 52.38%, 4.49%, and 245.95%, respectively. The output power is 24.5 mW with an external resistor of 8 kΩ, and the normalized power density is 153.14 × 10-3 mW/mm3, capable of powering light-emitting diodes (LEDs). This structure can drive wireless networks or low-power electronics.
ABSTRACT
In this paper, a nonlinear piezoelectric energy harvester is developed based on rotational motion applications. It consists of the pedestal, the piezoelectric beam, the connection mass, the tip magnetic mass, the revolving host, the support frame, and the bolts. This device drives the intermittent magnetic vibration between the magnet and the tip magnetic mass to generate electric energy, avoids mechanical collision and wear, and extends the service life of the device. The working principle and vibration model of the proposed energy harvester are studied theoretically. The displacement state of the piezoelectric beam under a magnetic force is simulated and analyzed. In addition, a series of experiments verify the simulation results. With two driving magnets, 5 g tip magnetic mass, and 10 mm radial excitation distances, a piezoelectric energy harvester can capture energy efficiently. The results demonstrate that the piezoelectric energy harvester produces four resonance frequencies of 4, 11, 15, and 19 Hz. When the rotation frequency is 4 Hz, the maximum open-circuit voltage of the piezoelectric energy harvester is 96.87 V. The piezoelectric energy harvester gets the maximum average power of 8.97 mW when the external resistance is 300 kΩ. At this time, the voltage across the resistance is 51.87 V.
ABSTRACT
In the past few decades, rotary energy harvesting has received more and more attention and made great progress. The energy harvesting device aims to collect environmental energy around electronic equipment and convert it into usable electrical energy, developing self-powered equipment that does not require replaceable power supplies. This paper provides a holistic review of energy harvesting techniques from rotary motion using piezoelectric materials. It introduces the basic principles of piezoelectric energy harvesting, the vibrational modes of piezoelectric elements, and the materials of piezoelectric elements. There are four types of rotational energy harvesting technologies: inertial excitation, contact execution, magnetic coupling, and hybrid systems. An overview of each technology is made, and then, a detailed analysis is carried out. Different types of rotating energy harvesting technologies are compared, and the advantages and disadvantages of each technology are analyzed. Finally, this paper discusses the future direction and goals of improving energy harvesting technology. This Review will help researchers understand piezoelectric energy harvesting to effectively convert rotational energy into electrical energy.