Transcript ppt
Embedded Power Vikram Patel PRESENTED IN DOUBLE VISION (WHERE DRUNK) 1 Outline Traditional Power ◦ ◦ ◦ ◦ Wall Warts Batteries Charging Common ICs Harvesting ◦ ◦ ◦ ◦ ◦ ◦ ◦ Piezoelectric Thermoelectric Solar Electromagnetic Capture MEMS Energy Storage Common ICs 2 Traditional Power Wall Adapters Batteries ◦ Primary ◦ Secondary 3 Wall Warts Plug Pack Plug-in Adapter Adapter Block Domestic Mains Adapter Power Adapter Wall Cube Power Brick 4 Wall Warts Available in 120 to 240 VAC Two Flavors ◦ Linear Power Supplies ◦ Switched-Mode Power Supplies Plethora of connectors 5 Wall Wart Considerations Voltage Current Voltage Stabilization Connector Type Polarity Longevity 6 Linear Power Supplies Transformer with a rectifier Possibly a filter to smooth out the DC Cons ◦ ◦ ◦ ◦ Large and Heavy Output varies with load unless linear regulator included Inefficient HEAT!!!!!!! 7 Linear Regulator 8 Linear Regulator 9 Linear Regulator 10 Switched-Mode Power Supplies Uses a switching regulator Smaller and higher efficiency Low quiescent current Cons ◦ ◦ ◦ ◦ More parts that can break No transient suppression Lots-O-EMI and audible When it dies it really DIES! 11 Switching Power Supply 12 Wall Warts In Summary Linear Power Supplies ◦ Inefficiency with longevity • Switched-Mode Power Supplies ◦ High efficiency with potential catastrophe 13 I Hate Cords Unless I using them to: ◦ Charge things ◦ Trip things ◦ Strangle things 14 Batteries!!! 15 Batteries! Portable (for the most part) Contains Yummy Toxic Chemicals Two Flavors ◦ Primary ◦ Secondary 16 Batteries! Contains the following friendly ingredients •Acid (varying types) •Lead •Nickel •Lithium •Cadmium •Alkaline •Mercury •Nickel metal hydride 17 Primary Cells Electrochemical reaction is not reversible!!! Disposable Most commonly used ◦ Zinc-Carbon ◦ Alkaline ◦ Lithium Bad for high drain applications 18 Lithium 1.5V 1.5 A Continuous 2A Pulse 90-150 mOhms IR Li/FeS2 Highest energy density readily available 19 Lithium Cathode Anode 20 Lithium FeS2 Cathode 4Li Anode FeS2 + 4Li →2 Li + Li2FeS2→Fe +2Li2S 21 Fuel Cells Considered as a primary cell Fuel can be replaced essentially “recharging” the battery Hydrogen fuel cells byproduct is H2O Other fuel types include: ◦ ◦ ◦ ◦ Methanol Ethanol Butane Propane 22 Fuel Cell – Basic Operation 23 Secondary Cells Electrochemical reaction is reversible!!! Very Portable (shape, weight) Most commonly used ◦ Lead Acid (car battery) ◦ Lithium Ion and Lithium Polymer ◦ Nickel-Metal Hydride Good for high drain applications Memory can be a problem 24 Explosions! Short circuits cause high currents Overcharging Hydrogen gas Fire/Heat 25 Leakage Battery chemicals can be ◦ ◦ ◦ ◦ Corrosive Poisonous Inflammable Flammable Remove batteries from electronics when not in use… IE WHEN SHIPPING! 26 Environmental Concerns Most batteries are only toxic to the environment in California Batteries may be harmful or fatal if swallowed Secondary cells are usually far more toxic then primary cells Materials in batteries can be cheaply reconstituted into new batteries 27 Lithium Secondary Batteries Lithium ◦ LiMnO2 Lithium Ion ◦ LiCoO2 Lithium Polymer (Li-poly, LiPo) ◦ LiMnO2 or LiCoO2 ◦ Electrolyte is held in a solid polymer and not in an organic solvent 28 Lithium Ion Popular for portable electronics One of the best energy-to-weight ratios No memory effect Very low charge loss 29 Lithium Polymer Electrolyte is held in solid polymer ◦ Polyethylene Oxide ◦ Polyacrylonitrile Modular Shape Lower cost (and falling) Rugged (temperature, cycles) Impressive death by puncture 30 Lithium Polymer 31 Charging 32 Charging Methods Constant Voltage Constant Current Taper Current Pulsed Charge Burp Charging IUI Charging Trickle Charge Float Charge 33 Constant Voltage Basically a DC power supply Used with ◦ Lead Acid ◦ Lithium Ion ◦ Lithium polymer 34 Constant Current Varies the voltage applied to maintain current Shuts off when voltage reaches the level of full charge Used with ◦ ◦ ◦ ◦ NiCad NiMH Lithium Ion Lithium polymer 35 Charging Lithium Ion/Polymer Step 1 – Apply charging current limit until the voltage limit per cell is reached. Step 2 – Apply maximum voltage per cell limit unit the current declines below 3% of rated charge current Step 3 – Apply top off charge when cell voltage drops 36 Pulse Charge 37 Specialized Charging Trickle charging a lithium battery will damage it! Pulse charging is the most energy efficient method 38 Battery Security Some batteries require a proprietary charger One wire authentication Special voltages Evil Iphone3G Battery 39 Single Cell LiPos Cellphone batteries Charging on USB Small Light Extensively Tested Designed for Longevity 40 USB Charging 41 Harvesting 42 Harvesting Sources Piezoelectric Thermoelectric Solar Electromagnetic Capture MEMS 43 Piezoelectric Creates electric potential when mechanical strain is applied Common materials ◦ ◦ ◦ ◦ ◦ Lead Zirconate Titanate (PZT) Bismuth Ferrite (lead free) Quartz Topaz Cane Sugar Crystals (yummy) 44 Piezoelectric 45 Piezoelectric Generates up to +/-90V Voltage generated is directly proportional to surface area Requires voltage clamping or step-down transformer 46 Piezoelectric Energy Harvesting Sources ◦ Human motion (people energy) ◦ Acoustic noise ◦ A lot more…. Achieved applications ◦ Doorbells ◦ Remote controls ◦ Battery charging 47 Thermoelectric Generators (TEG) Converts temperature differences into electric potential differences Uses the Peltier effect Can be “fabbed” directly into ICs 48 Thermoelectric Generators (TEG) 49 Thermoelectric Generators (TEG) Sources ◦ Anything that produces a temperature higher then the ambient environment Humans Cars ICs Can be used to cool things ◦ TEGs can be placed on CPUs 50 On Chip TEGs Used in “flip-chip” packaging Intel and IBM will use this first Recycles heat into power for reduced processor wattage and longer battery life 51 Nifty Usage 52 Nifty Usage 53 Solar Uses photovoltaic cells (PV) Cell efficiency ranges from 7-16+% Produces DC without rectification DC output can vary greatly depending on ◦ Light source availability ◦ Inclination of the cell ◦ Temperature 54 Solar Efficiencies are rapidly rising Mass-production cost are rapidly falling Best used to augment standing DC supply Storage of energy reduces efficiency 55 Experimental Solar Multi-junction solar cells with TEGs Still in experimental stage Expected 50% efficiency without increased cost 56 Nifty Usage 57 Electromagnetic Capture Transforms kinetic energy into electrical via electromagnetic conversion 58 Electromagnetic Capture Most commonly used energy harvesting method 59 Electromagnetic Capture 60 Wireless Energy Harvesting Converts electromagnetic radiation from ◦ ◦ ◦ ◦ Wi-Fi Cell phone antennas TV masts Radio Stations Uses a wideband antenna (500MHz-10GHZ) Horrible efficiency Solar power would work better 61 Storage Battery Capacitors Super Capacitors 62 Battery Storage Un-regulated trickle charging possible for lead acid batteries Pulse charging required for Li-ion/Poly Can be “plugged in” for quick charge High energy density Battery cycles limit the lifetime of the storage Leakage ≈ 10%/month 63 Capacitor Storage Low Leakage is key Best used in applications where timing of operations is not important ESR should not matter unless high drain applications are planned 64 Super Capacitors Regular capacitor area is measured by the area of the plates separating the dielectric Super caps utilize highly porous carbon materials ◦ ≈2000 square meters of surface area per gram C A d 65 References http://www.eetasia.com/ART_8800378146_765245_NT_27d01882.HTM http://electronicdesign.com/article/power/energy_harvesting_ics_supply_all_system_voltages_directly_from_transducers.a spx http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1799,P111807#descriptionSection http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1037,C1078,C1088,P90562 http://www.sensorsportal.com/DOWNLOADS/MEMS_Energy_Harvesting_Debvices.pdf http://www.technologyreview.com/communications/22764/?a=f http://www.nextnature.net/2008/02/biomechanical-energy-harvesting/ http://www.sensorsportal.com/DOWNLOADS/MEMS_Energy_Harvesting_Debvices.pdf http://www.ise.fraunhofer.de/press-and-media/press-releases/press-releases-2009/world-record-41.1-efficiency-reached-formulti-junction-solar-cells-at-fraunhofer-ise http://arstechnica.com/hardware/news/2008/01/startup-shrinks-the-peltier-cooler-and-puts-it-inside-the-chip-package.ars http://www.ibtimes.com/articles/41154/20100805/apple-battery-charger-iphone.htm http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en026250 http://www.maxim-ic.com/datasheet/index.mvp/id/6821 http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1037,C1078,C1088,P9551 www.wikipeida.com 66