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EETE SEP 2015

Shock absorber harvests energy from car’s suspension By RRich Pell esearchers at Virginia Tech’s College of Engineering (Blacksburg, VA) have developed a shock absorber system designed to harvest large-scale vibrational energy from a car’s suspension. Using a combination of gears allowing motion in both directions, the energy-harvesting shock absorber works by converting the vertical vibrations of a moving car’s suspension into a rotational motion that turns a generator. The generated electricity is then delivered directly to the car’s battery or electronic devices, reducing demands on the alternator. According to Lei Zuo, associate director of the Virginia Tech Center for Energy-Harvesting Materials and Systems, a car’s shock absorbers should be able to provide between 100 and 400W on normal roads (and even more on bumper roads). Tests of the energy harvesting shock absorber on campus roads, he says, have shown that the system can capture about 60% of the available energy. The test model was constructed by students using off-theshelf components. According to the researcher, an efficiency of 85% should be achievable if this system is built using precision components and manufacturing. The next phase of development will focus on cost and performance. Zuo is looking into a MPU-controlled system using self-powered semi-active control, where suspension settings would adjust automatically to vehicle and road conditions for optimum comfort and energy harvesting. Startup offers energy harvest management IC Startup company E-peas Semiconductors (Liege, Belgium) has announced its first chip in energy management IC for use with photovoltaic and thermoelectric energy harvesting. The AEM1x940 is an energy management IC that extracts DC power from photovoltaic cells or thermoelectric generators to supply electronic systems in order to extend their battery life and ultimately get rid of the primary storage element. It uses a low power boost converter that can operate with input voltages in the range of 100mV up to 2.5V. With a special “cold-start” circuit it can start operating with empty storage elements at an input voltage as low as 380mV and an input power as low as 3μW, according to the e-peas website. The device includes two LDO regulators for 1.8V output at up to 10mA load and a variable LDO at 2.5V to 4V with up to 30mA load current. Overcharging and over-discharging protection are provided and the design is described as being RF transmission friendly. No Boundaries Our mission-critical resistors are truly out of this world. In fact, soon they will be out of our solar system, helping NASA’s Voyager spacecraft travel where no Earth craft has gone before. Thirty-fi ve years and 11 billion miles... Now that’s reliability. State of the Art, Inc. RESISTIVE PRODUCTS Made in the USA. www.electronics-eetimes.com Electronic Engineering Times Europe September 2015 37


EETE SEP 2015
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