利用能量收集进行电力接入控制

　　利用能量收集进行电力接入控制

　　电源是一个关键的挑战，适合访问控制系统，如电子锁。能够从环境中提供这样的设备提供更低的成本，更容易集成和配件，并有可能使整个系统更安全，消除了切割电源的脆弱性。本文着眼于使用能源收集和电源管理提供加密的无线接入控制系统，连接到互联网的东西，特别侧重于太阳能的能源选项。

　　在智能建筑的改造中，向门禁系统提供电源是一个关键的限制。运行电力电缆上下的门可能是复杂和昂贵的，系统架构师正在寻找不同的方式来提供智能系统的电源。成千上万的门锁经常更换电池是昂贵的，在许多情况下不切实际。

　　相反，能量收集提供了机会，没有大量的布线提供电力，但有一些关键的考虑，无论是在安装和系统设计，取决于能源。

　　The two most appropriate energy harvesting technologies for access control are solar and thermal power. While these generate relatively small amounts of current， this works for access control where small bursts of power are required to authorize access – usually through a wireless link or a card swipe - and release a lock from the captured and stored current. A wireless link back to a monitoring gateway also provides more security and can be used to trigger alarms if the power is cut or there are unauthorized attempts at entry. Using an energy harvesting approach with a wireless link eliminates the need for a costly cable infrastructure and simplifies the retrofitting of such systems.

　　For external doors， the difference in temperature can be harnessed by energy sources using the Peltier Effect. This makes use of the different electrical and thermal properties of metals so that a Peltier engine， such as the WPG-1 from Laird Technologies （Figure 1）， can be installed in a door or through a wall with one side warmer than the other. This then generates a current that can be used to charge a battery to power the access control system.