基于应用环境的路用压电俘能单元尺寸优化与性能评价

Size Optimization and Performance Evaluation of Road Piezoelectric Energy Harvesting Unit Based on Application Environment

为提高路用压电发电装置内部堆叠式压电俘能单元在电-力-环境方面的综合性能,基于电学理论优选了压电俘能单元结构尺寸范围,基于应用工况的力学响应优选了力学特性良好的压电俘能单元结构尺寸,系统研究了不同道路交通条件下不同结构尺寸路用压电俘能单元电学性能,揭示了不同道路温湿环境下压电俘能单元电学性能变化规律,探明了不利循环交通荷载条件下路用压电俘能单元抗疲劳性能,并明确了路用压电俘能单元极限抗压强度。结果表明:堆叠式压电俘能单元电学性能及力学特性受其结构尺寸影响明显,兼具较高电学与较优力学特性的压电俘能单元尺寸范围为直径15 mm、厚度30 mm、堆叠层数25~30层(Φ15-30 mm-25~30),其中Φ15-30 mm~25压电俘能单元在不同道路交通条件下电学输出水平更高,3.5 kN~8 Hz工况下其输出电压和输出功率可达176 V、192.2 mW;20℃~60℃温度范围内其输出电压变化率为17.9%,而50%~100%湿度范围内其输出电压变化率达84.1%,实际应用中可适当采取一定的封装隔温保护及必要的封装隔湿保护;压电俘能单元抗疲劳性能良好,3.5 kN~8 Hz不利交通组合、10万次循环加载后其输出电压最大变化率仅为1.2%,最大变形量仅为1.8 mm;压电俘能单元极限抗压强度达188 MPa,远高于道路荷载水平,能够满足道路应用要求。研究结果可进一步提高路用堆叠式压电俘能单元综合性能,推动道路压电发电技术实际应用进程。

To enhance the comprehensive performance of the stacked piezoelectric energy harvesting unit of the road piezoelectric power generation device concerning electricity-mechanics-environment, the structural size range of the energy harvesting unit was selected based on the electrical theory. Meanwhile, the structural size of the energy harvesting unit with good mechanical properties was optimized based on the mechanical response of the application conditions. The electrical properties of piezoelectric energy harvesting units with different structural sizes under different road traffic conditions were systematically studied. Besides, the variation laws of electrical properties of energy harvesting units under different road temperature and humidity were also revealed. The fatigue resistance of the piezoelectric energy harvesting units under unfavorable cyclic traffic load conditions were ascertained, and the ultimate compressive strength of the energy harvesting units were clarified. The results show that electrical properties and mechanical properties of the stacked piezoelectric energy harvesting units are significantly influenced by its structural size, and energy harvesting unit with a size range of 15 mm in diameter, 30 mm in thickness and 25-30 layers(Φ15-30 mm-25-30) features higher electrical and mechanical properties. Among them, the energy harvesting unit with a size of Φ15-30 mm-25 has higher electrical output, its output voltage and output power can reach 176 V and 192.2 mW under 3.5 kN-8 Hz working conditions. With its output voltage change rate being 17.9% in the temperature range of 20 ℃-60 ℃ and being 84.1% in the humidity range of 50%-100%. As a result, a certain packaging temperature insulation protection and the necessary packaging moisture protection can be adopted appropriately in the practical applications. The piezoelectric energy harvesting units exhibit satisfying fatigue resistance, the maximum change rate of the output voltage and the maximum deformation are only 1.2% and 1.8 mm after 100 000 times of unfavorable traffic loading of 3.5 kN-8 Hz, respectively. Apart from that, the ultimate compressive strength of the piezoelectric energy harvesting unit reaches 188 MPa, which is much higher than the road load level and can satisfy the requirements of the road applications. This work can further foster the comprehensive performance of the road stacked piezoelectric energy harvesting unit, and promote the actual application process of road piezoelectric power generation technology.