井下微能量收集装置设计

Design of underground micro energy harvesting device

  • 摘要: 井下无线传感节点能量有限,可利用能量收集技术将井下环境能量转换为电能为传感节点供电,从而延长无线传感节点生命周期。测试并分析了井下巷道弱光环境下光照强度,结果表明距光源1~2 m范围内,光照强度为50~170 Lux,符合非晶硅、钙钛矿等光电材料工作范围,因此将井下弱光能量转换为电能具有可行性。采用30 cm×40 cm非晶硅光伏电池板、BQ25505型电源管理芯片和锂电池设计了一种井下微能量收集装置,可将井下弱光能量转换为电能并存储。针对井下环境能量不连续的特点,设计了能量缓存机制,即采用容量较小的可充电锂电池为能量缓存电池,选用较大固定容量的锂电池为备用电池,当可充电锂电池电压达到设计值时由其供电,当电压不足时切换备用电池供电,确保无线传感节点正常工作。对微能量收集装置进行了实验室及井下测试,结果表明:装置在50 Lux以上光照强度条件下即可输出毫瓦级电能;当井下光照强度达到170 Lux以上时,装置能够利用转换的能量为低功耗无线传感节点供电,无需启用后备电池;当光照强度未达到170 Lux时,能量缓存机制协调可充电锂电池和备用电池为无线传感节点供电,有效提高了节点生命周期。

     

    Abstract: Underground wireless sensor nodes have limited energy. Hence, energy harvesting technology can be used to convert underground environmental energy into electrical energy to supply power to the sensor nodes, thus extending the life cycle of wireless sensor nodes. The light intensity in the low light environment of the underground roadway is tested and analyzed. The results show that the light intensity is 50-170 Lux in the range of 1-2 m from the light source, which is in line with the working range of photoelectric materials such as amorphous silicon and perovskite. It verifies the feasibility of converting the underground low light energy into electrical energy. An underground micro energy harvesting device is designed by using 30 cm×40 cm amorphous silicon photovoltaic panels, BQ25505 power management chip and lithium batteries, which can convert the underground low light energy into electrical energy and store it. According to the characteristics of discontinuous energy in the underground environment, an energy caching mechanism is designed. In this mechanism, a rechargeable lithium battery with smaller capacity is used as the energy caching battery, and a lithium battery with larger fixed capacity is selected as the backup battery. When the voltage of the rechargeable lithium battery reaches the design value, the sensor node is powered by the rechargeable lithium battery. And when the voltage is insufficient, the backup battery is switched to supply power to ensure the normal operation of the wireless sensor node. The micro energy harvesting device has been tested in the laboratory and underground. The results show that the device can output milliwatt power with the light intensity above 50 Lux. When the underground light intensity reaches 170 Lux or more, the device can use the converted energy to power the low-power wireless sensor node without backup battery. When the light intensity does not reach 170 Lux, the energy caching mechanism coordinates the rechargeable lithium battery and the backup battery to power the wireless sensor node, which improves the node life cycle effectively.

     

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