Research And Design Of MIMO Environmental Energy Harvesting System Based On Single-inductor DC-DC

Environmental energy harvesting(EEH)has become popular in recent years,as it provides a potential solution for powering unattended electronic devices,especially for applications in remote areas and wireless sensor networks for Io T devices.However,the traditional single-input single-output EEH system is not sufficient to meet the need for stable and applicable power supply.A multi-input multi-output(MIMO)EEH system has been proposed for better power stability and applicability.Nevertheless,the output voltage ripple and efficiency of MIMO systems may decrease when facing variable loads.In this thesis,we propose a single inductor-based multiple input multiple output(SIMIMO)EEH system that can achieve high conversion efficiency and low output voltage ripple in a wide range of loads,aiming to address the low output voltage ripple and variable efficiency issues of the existing EEH systems.To overcome the low efficiency and varying efficiency issues of existing EEH systems,this thesis analyzes the energy loss of the EEH system and proposes several solutions to reduce switching loss,clock drive loss,and system static loss.Firstly,to reduce switching loss,this study analyzes different converter topologies and selects the one with the lowest switching loss.Secondly,to minimize clock drive loss,an Adaptive System Clock Frequency(ACF)control circuit is designed,which improves the efficiency of traditional methods in light load and ensures the system achieves high efficiency in a wide range of loads.Thirdly,to minimize the static loss of the system,a low-power maximum power point tracking circuit,a low-power input/output voltage sampling circuit,and a low-power wide output range zero-crossing detection circuit are designed.To address the issue of output ripple from the environmental energy harvesting(EEH)system,which varies with the load,an Optimal Conduction Time(OOT)-based control method is proposed in this thesis.This method aims to reduce the ripple in cases of small load capacitance and light loads.It effectively solves the problem of large ripple that typically occurs with the traditional control method.In addition,this thesis designs different working modes for various scenarios of multi-input multi-output energy harvesting systems,prioritizes multiple types of input sources and multiple outputs,and addresses the situation when multiple input sources or output terminals request power at the same time.Furthermore,overvoltage and undervoltage protection modes for energy storage batteries are designed to extend the battery ’ s lifespan.To implement an unattended power supply system,this thesis also presents a self-starting circuit that combines the advantages of capacitive and inductive systems.This circuit solves the problem of voltage switching during starting,ensuring a smooth and reliable system start-up.In conclusion,this thesis proposes a single-inductor DC-DC MIMO energy harvesting system that is implemented and evaluated using CMOS 180 nm technology.The simulation results demonstrate that the proposed system achieves a peak efficiency of 89.75% and a minimum efficiency of 83.75%,which is over 7 percentage points higher than similar systems.Furthermore,the output ripple decreases significantly,from 177.96 m V to23.56 m V at 0.2u F load capacitance.These results confirm the effectiveness of the proposed system in reducing energy loss and maintaining a stable power supply,which has great potential for practical applications in various implementing scenarios.