Comparison of piezoelectric and electromagnetic energy harvesting methods for intelligent tyre systemsAS-0.3100 Automaatio- ja systeemitekniikan seminaari23.10.2015Otso Jousimaa

Why?Why intelligent tyres?Why energy harvesting?

Intelligent tyresPresent: pressure sensingFuture: Contact quality sensing?

[Three Three-Axis IEPE Accelerometers on the Inner Liner of a Tire for Finding the Tire-Road Friction Potential Indicators; Niskanen, Tuononen]

Power requiredSleep: ~17 µAActive: ~5 mA[ LOW POWER TIRE PRESSURE MONITORING SYSTEM , Goparaju]

Battery?620 mAh~4 years sleep~5 days active

[Energizer CR2450 datasheet]

Harvesting methodsThermalRFElectromagneticPiezoelectric

PhotovoltaicTriboelectricMagnetostrictiveElectrostatic

Piezoelectric

[Vibrational energy harvesting; Stewaart et al.]

Strain -> electricityHigh voltage High output impedance

600µW – 2,6 mW?[Wikipedia]

ElectromagneticVarying magnetic field -> electricity

Low voltage

Low output impedance

[Electrical power generating tire system ]

Generator impedance was 42 ohms –> ~100µW to 42 ohm load?

FeasibilitySleep power can be providedContinuous activity not possibleDuty cycle of sensor 0.8% - 20%?

Practical mattersReliability?Efficiency of rectification?Storage / conversion losses?

ConclusionUseful power levels are attainable.Rectification loss for EM generator is unacceptable.Experimental work to verify feasibility

Thank you!Questions?