一种上变频自供电无线传感器电源管理电路

电线周围的电磁场能量密度低,电磁换能器采集到的能量通常无法直接驱动无线传感器正常工作.论文采用上变频技术,设计了一种自供电电源管理电路来提高能量采集效率.由于电路的输出功率与品质因数成正比,且品质因数的大小与电路谐振电容的根号值成反比,因此通过提高电路的工作频率来减小谐振电容值,可以使高品质因数的电路产生更高的输出功率,进而增加能量采集效率.实验结果表明,该电路的最大能量采集效率是传统桥式整流电路的2.1倍.当电线中通过1A、50Hz的交流电时,电源管理电路最大采集功率为780μW,能量采集效率达到48.75%.当管理电路中超级电容能量积累达到一定程度,电容放电驱动无线传感器工作.

A Frequency Up-Conversion Self-Powered Power Management Circuit for Wireless Sensors

As the output power of electromagnetic energy harvester is not sufficient to drive the wireless sensor in weak power density,a power management circuit using frequency up-conversion is proposed for harvesting electromagnetic energy around power lines.Because the output power of the resonant circuit increases with the quality (Q) factor which is inversely proportional to the square root of the circuit resonant capacitor,the proposed frequency up-conversion matching circuit working at a higher resonant frequency with a smaller resonant capacitor can obtain a higher Q factor,a stronger output power and a lower energy loss.Experimental results reveal that the maximum charging power of this management circuit is 2.1 times higher than that in the traditional full-bridge rectifier circuit.A maximum charging power of 780μW and a harvest efficiency of 48.75% are achieved at a line current of 1A and a frequency of 50Hz.When the electric energy accumulates to a certain level,the storage capacitor will discharge to drive the wireless sensor.