Research On Wireless System Based On Indoor Low-Light Energy Harvesting

The smart building,as an interactive system of human-information-network-building,necessitates the construction of internet of things featured with massive sensors.However,a remaining major challenge is the power supply to terminal nodes.Amongst the various solutions,a self-powered sensor network using ambient energies shows the most promising development prospects.Indoor light energy is known to be a long-term sustained renewable energy source and is easy to collect using photovoltaic technology.However,indoor light harvesting technology confronts several issues,such as unstable light levels and low conversion efficiency.To match the self-powered wireless sensor network,comprehensive and sophisticated power management,as well as lighting control,must be pursued,resulting in a flexible and efficient smart lighting system.To achieve this goal,this thesis accomplishes the following work:(1)The distribution of indoor ambient energy sources and the associated harvesting technologies are reviewed and analyzed.Light energy is selected as the ambient energy source.The characteristics of the indoor light environment and various maximum power point tracking technologies are studied to provide guidance for the photovoltaic technology selection and power supply circuit design.(2)A static system model for different lighting and temperature conditions is developed which includes on the loss modeling of the load,indoor light harvesting model,maximum power point tracking and power management model.The arrangement of photovoltaic panels is then optimized for the maximum output power,and the system’s performance is analyzed and verified using a transient model.(3)An indoor light harvesting based self-powered wireless sensor network is achieved using the optimal photovoltaic panel arrangement.Considering the wireless node power consumption,such wireless sensor network utilizes a ZigBee based star topology.The energy flow analysis using the static model has been carried out to ensure that the light harvesters can provide sufficient energy to the wireless sensor node,i.e.,a practical real-world self-powered wireless sensor node.In this paper,the static model was used to optimize the output of the light harvesting system.Under the average laboratory light of 340 Lux and room temperature of 25 ℃,the output power of the light harvesting system was increased by 12.91%,reaching 352.55μW.(4)Based on a self-powered wireless sensor network realized by means of indoor light harvesting,a smart lighting system,which not only optimize system energy consumption,but satisfies the real-time user preference of the lighting for work bench,is synthesized.To sum up,this thesis provides a universal indoor light harvesting based self-powered wireless sensor network technology.A simulation platform is also developed which can be applied to analyze and optimize the self-powered wireless sensor system.Moreover,a real-time adaptive regulation algorithm is developed to match with the self-powered oriented applications.The indoor light harvesting based self-powered sensor network,the simulation platform,and the and the real-time adaptive regulation algorithm proposed have been applied and verified in a real smart lighting system.