EnTON – Energy Transfer Optimizing Circuits for Energy Harvesting Applications

能量收集能够将环境能量转化为电能，以便为原本由电池或电缆驱动的设备提供电力。例如，考虑到像Industry 4.0或物联网这样的应用，必须在分散的位置安装大量传感器来执行状态监控。通过电缆或电池为这些设备供电是维护和成本密集的，这就是为什么能量收集是这类应用的关键技术。由于其数学证明的100%的效率，该研究项目的目标是首次评估能量收集方法恒定负载仿真的完全集成实施。这项研究将集中在匹配负载电阻，重点是基于输入和输出电压的函数。虽然通常被忽略，但只有两种情况可以容忍这种简化：处于不连续导通模式的Boost Buck转换器和处于边界模式的Boost转换器。为了达到普遍的适用性，必须考虑输入和输出的相关性，以避免效率的降低。为了满足这一目标，将探索和评估创新的电路设计技术，以便与最大功率点跟踪(MPPT)和开关模式转换器的现有技术相比降低功耗。结合算术负载匹配和爬山两种最大功率点跟踪方法，根据MOS晶体管的电压-电流特性，推导出基于超低功耗模拟电路的最大功率点跟踪算法。对于算术负载匹配，需要一种用于输入和输出电压相关占空比的超低功率计算技术。对于爬山方法，设想了一种超低功耗模拟电路来计算转换后的能量。此外，还将开发创新的电路设计技术，以降低零电流检测器的开关延迟和功耗，从而实现高性能的开关转换器。总体而言，使用几百微亨利的现成电感实现紧凑和节能的采集系统将成为可行的。经过理论评估，所有方法都将被实现，并通过专用CMOS集成电路来验证其性能。

Energy Harvesting enables the conversion of ambient energy into electrical energy in order to provide power to devices that otherwise would be battery or cable driven. Considering applications like Industry 4.0 or the Internet of Things, numerous sensors must be mounted in decentralized locations to perform condition monitoring, for example. Powering these devices by cables or batteries is both maintenance and cost intensive which is why energy harvesting is a key technology for such applications.Motivated by its mathematically proven efficiency of 100%, the objective of this research project is to evaluate for the first time a fully-integrated implementation of the energy harvesting approach Constant Load Emulation. This research will focus on a matched load resistance with the emphasis on a function based on both the input and the output voltage. Although usually neglected, only two cases can tolerate this simplification: the boost buck converter in discontinuous conduction mode and the boost converter in boundary mode. For a general applicability, the input as well as the output dependence must be considered to avoid a reduction in efficiency.To meet this objective, innovative circuit design techniques will be explored and evaluated in order to reduce the power consumption compared with the state of the art for both the maximum power point tracking (MPPT) and the switch-mode converter. Considering the two MPPT-approaches, Arithmetic Load Matching and Hill Climbing, calculation methods will be derived using ultra-low-power analog circuits based on the voltage-to-current characteristic of the MOS transistor. An ultra-low-power calculation technique for an input and output voltage-dependent duty cycle is required for the Arithmetic Load Matching. For the Hill Climbing approach, an ultra-low-power analog circuit is envisioned for calculating the converted energy. Furthermore, innovative circuit design techniques will be developed to reduce both the switching delay and the power consumption of the zero-current detector resulting in a high performance switching converter. Overall, the implementation of compact and energy-efficient harvesting systems using off-the-shelf inductances of a few hundred micro-henry will thus become feasible.After a theoretical evaluation, all approaches will be implemented and their performance verified by means of an application-specific CMOS integrated circuit.