energy harvesting
DESCRIPTION
Energy Harvesting. Thomas Vermeer 3/25/09 Embedded Systems. Agenda. What is Energy Harvesting? Common Energy Harvesting Systems Energy Sources Energy Storage Optimization Methods. Energy Harvesting. What is Energy Harvesting? - PowerPoint PPT PresentationTRANSCRIPT
Energy Harvesting
Thomas Vermeer3/25/09
Embedded Systems
Agenda
• What is Energy Harvesting?• Common Energy Harvesting Systems• Energy Sources• Energy Storage• Optimization Methods
Energy Harvesting
What is Energy Harvesting?
• Energy Harvesting is a way of powering an embedded system by ‘harvesting’ energy from the environment
Energy Harvesting
Common Energy Harvesting Systems
Energy Harvesting
Common Energy Harvesting Systems
• Car Tire Pressure Monitors
Energy Harvesting
Common Energy Harvesting Systems
• Wireless Weather Stations
Energy Harvesting
Common Energy Harvesting Systems
• Implantable Medical Devices
Energy Harvesting
Common Energy Harvesting Systems
• Traffic Alert Signs
Energy Harvesting
Common Energy Harvesting Systems
• Mars Rover
Energy HarvestingTwo Design Goals:
• Choose very low power electronics• Harvest and store energy efficiently
Energy Harvesting
Sources of Energy:
Energy Harvesting
Sources of Energy:
• Solar
Energy Harvesting
Sources of Energy:
• Mechanical
Energy Harvesting
Sources of Energy:
• Thermal
Energy Harvesting
Sources of Energy:
• Electromagnetic
Energy Harvesting
Energy Storage
Energy Harvesting
Energy StorageOption 1:
Traditional Rechargeable Batteries
Energy Harvesting
Energy StorageOption 1:
Traditional Rechargeable Batteries• Inefficient charging – lots of energy
converted to heat
Energy Harvesting
Energy StorageOption 1:
Traditional Rechargeable Batteries• Inefficient charging – lots of energy
converted to heat• Limited number of charging cycles
Energy Harvesting
Energy StorageOption 2:
Traditional Capacitors
Energy Harvesting
Energy StorageOption 2:
Traditional Capacitors• Efficient charging
Energy Harvesting
Energy StorageOption 2:
Traditional Capacitors• Efficient charging
• Limited Capacity
Energy Harvesting
Energy StorageOption 3 – Best Option:
Super Capacitors
Energy Harvesting
Energy StorageOption 3 – Best Option:
Super Capacitors
• Efficient charging and high capacity
Energy Harvesting
Super Capacitors• Small Size• High Efficiency• Very high capacity (1-100 Farads)• ~20% capacity drop per decade
Energy HarvestingMaximizing Energy Stored
What if our system charges at 5V?
Energy HarvestingMaximizing Energy Stored
We could charge system when Vin>5V, or for about 5 hours/day
Energy HarvestingMaximizing Energy Stored
But look at all this wasted energy!
Energy HarvestingMaximum Power Point Tracking
Energy HarvestingMaximum Power Point Tracking
Uses buck/boost voltage regulators
Energy HarvestingMaximum Power Point Tracking
Uses buck/boost voltage regulators• “Buck” the voltage down at peak times,
supplying 5V with high current
Energy HarvestingMaximum Power Point Tracking
Uses buck/boost voltage regulators• “Buck” the voltage down at peak times,
supplying 5V with high current• “Boost” the voltage up at lower times,
supplying 5V with low current
Energy HarvestingAutonomous Maximum Power Point Tracking
• Preprogrammed regulators• Feedback circuits• Inexpensive• Easy to implement• Low power overhead
Energy HarvestingActive Maximum Power Point Tracking
• Uses MCU or DSP• Difficult implement• High power overhead• Can be counterproductive
Energy Harvesting
Any Questions?