Electronic Design

Heat Powers Wireless Devices

These days everyone is looking for the next cheap, not just inexpensive but cheap, source of electrical power. This is obviously a response to the rising cost of everything, usually with price increases blamed on fuel and energy costs. Also, factor in the quest to save the global environment from the effects of previous energy-seeking/-burning endeavors and the race is on for even more sources of CHEAP energy.

Nextreme Thermal Solutions of Durham, NC, USA offers one method of generating electrical energy from heat. Thermobility, what the company calls the next generation of power generation technology, uses heat as a source of electricity for low-power wireless applications. Naturally, there are other applications that can benefit from this technology.

Thermobility employs solid-state thin-film thermoelectric technology to convert heat into electricity by using differences in temperature to deliver power anywhere there is a suitable heat source. As per Nextreme, it can eliminate the need for wired power sources or batteries. Used with wireless transmitters in particular, Thermobility can provide decades worth of low-cost, maintenance-free electric power. Bottom line here is endless possibilities for unique wireless sensor applications in industrial control, transportation, automotive, and building management.

What Is It And How Does It Work?
The WPG-1 is the first power module flying under the Thermobility flag (see figure). It provides a constant voltage output of 3.3, 4.1, or 5 Vdc into 15-k? loads or higher. Around the size of a golf ball, the module consists of a pin-fin heat sink, circuit board, the company’s TEG HV56 thermoelectric power generator module, and a metal plate, As seen in the figure, the module attaches to suitable heat source, in this case a heatsink.

For voltage-conversion chores, the module enlists a Linear Technologies LTC 3108 ultralow-voltage step-up converter and power manager. The converter chip delivers up to 1 mW of power at temperature differentials as low as 15K to 20K relative to ambient. Larger temperature differences will obviously generate more power.

A Way Cool Idea
Keeping things simple, the WPG-1 is pretty easy to use with any flat-surface heat source. For example in bench-top testing, users can place the module directly on a lab hotplate with temperature control. On other surfaces, the attachment plate can mate with either thermal grease for horizontal deployment or a double-stick thermal pad for vertical mounting. For setting output voltages, the module’s PCB supports DIP switches and all electrical connections are made using two- or six-pin connectors with the six-pin connector being a proprietary connector from Texas Instruments that mates to the eZ430 wireless target board.

The company plans to extend the WPG-1 feature set in the future with integrated energy storage for applications working with variable heat sources. At the moment, the design is quite flexible and customizable for a variety of wireless apps. Currently, the Thermobility WPG-1 generator is available for evaluation with a six- to eight-week lead time. Price is $495. For more info visit the company’s website at www.nextreme.com/thermobility or call NEXTREME THERMAL SOLUTIONS INC., Durham, NC. (919) 597-7300.

TAGS: Automotive
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