Energy Harvesting with Wiegand

The continuing growth of the Internet of Things (IoT) market not only increases productivity and opens up new business models, but also places new requirements on the devices involved. These requirements address reliability, precision, autonomy, and freedom from maintenance.

Prominent participants in the IoT are ubiquitous sensing devices that do not rely on cable connections and can therefore be placed at any spot. Hence, the usage of energy available in the environment ("energy harvesting") to power sensor technology and wireless information transmission are of paramount importance.

There are a variety of environmental energy harvesting technologies each having distinct characteristics. Prominent approaches for energy harvesting such as photovoltaic, thermoelectric and RF harvesting rely on the environmental availability of the respective energy form. Induction-based energy harvesters are a well-established method to harness kinetic energy. One drawback of induction-based energy harvesters is the low level of energy harnessed at very low kinetic speeds. Wiegand effect energy harvesting carries the advantages of inductive energy harvesting without the reliance on mechanical parts to overcome the challenge at low speeds.

Thanks to its impressively low energy demands, accuracy for Time-o-Flight measurements and ability to ‘co-exist’ with narrowband wireless technologies. UWB is already finding great success in numerous applications. With UWB the transmitting power is only consumed by short pulses instead of a constantly powered frequency generator making it an excellent candidate for the wireless transmission technology employed in a wireless sensor node supplied by energy harvesting from a Wiegand generator.

The unique characteristics of Wiegand effect can be harnessed to power a circuit that performs data acquisition, processing, and wireless transmission in a pulsed, “single-shot” operating mode. Potential applications of such a system include door or window opening sensors for smart-home applications or industrial logistic automatization. The ability to sense other physical properties also makes this idea suitable for condition monitoring in the vicinity of moving parts (e.g. pumps, wind mills, turbines, wheels, assembly belts, etc.). This can result in a novel plug-and-play solution for situations, where a power supply via cable, battery or other energy harvesting technologies was so far impossible or uneconomical.

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