摘要
An improved harvester available in scavenging energy from the operating environment with either weaker or stronger vibration levels is studied. To ensure the optimal harvester performance, a Cuk dc-dc converter is employed into the modulating circuit. This paper reports how this harvester scav- enges maximal energy from varying-level vibrations and store energy into an electrochemical battery. Dependence of the duty cycle upon the external vibration level is calculated, and it is found that: 1) for weaker vibrations, the charging current into the battery is smaller than the allowable current, and thus all the optimal output power of the harvesting structure can be absorbed by the battery. In this case, the duty cycle should be fixed at 1.86%; 2) for stronger external forcing, the allowable charging current of the battery is smaller than the optimal harvested current. This indicates that just a portion of the sca- venged energy can be accepted by the battery. Thus, the duty cycle should be decreased gradually with the increase of the vibration level. Finally the energy transmission process and the roles of each elec- tronic element are analyzed. It is shown that a Cuk converter can greatly raise the efficiency of such a harvester, particularly when subjected to a weaker ambient vibration.
An improved harvester available in scavenging energy from the operating environment with either weaker or stronger vibration levels is studied. To ensure the optimal harvester performance, a Cuk dc-dc converter is employed into the modulating circuit. This paper reports how this harvester scavenges maximal energy from varying-level vibrations and store energy into an electrochemical battery. Dependence of the duty cycle upon the external vibration level is calculated, and it is found that: 1) for weaker vibrations, the charging current into the battery is smaller than the allowable current, and thus all the optimal output power of the harvesting structure can be absorbed by the battery. In this case, the duty cycle should be fixed at 1.86%; 2) for stronger external forcing, the allowable charging current of the battery is smaller than the optimal harvested current. This indicates that just a portion of the scavenged energy can be accepted by the battery. Thus, the duty cycle should be decreased gradually with the increase of the vibration level. Finally the energy transmission process and the roles of each electronic element are analyzed. It is shown that a Cuk converter can greatly raise the efficiency of such a harvester, particularly when subjected to a weaker ambient vibration.
基金
Supported by the National Natural Science Foundation of China (Grant No. 10872074)
the National Basic Research Program of China (Grant No. 2009CB724205)
