Control Strategies of Hybrid Energy Harvesting—A Survey

In this article, we deal with the problem of Hybrid Energy Harvesting control strategies, while paying attention to their properties and suggesting criteria to assess their suitability for specific energy harvesting techniques, as well as their application in different areas of technology—especially Wireless Sensor Networks and the Internet of Things. Many research works have already been published on the topic of combining resources for Energy Harvesting; nevertheless, a comprehensive review of the control strategies for such systems and a comparison of their most important properties is missing. This is the genesis and the main subject of this article. We have performed a deep research investigation of available resources. We have identified eight different control strategies and defined a set of the most important parameters (including their possible ranges/states) as criteria to be able to compare them. The corresponding sections of this article begin with a general description of the respective strategies and their principles (including generalized schemes), which is followed by specific examples of best practices. The key conclusions of the performed analysis are summarized in a comparison table that allows the readers to make their own conclusions and choices.