Darnell nanoPower Forum - Today, engineers from Powercast and CAP-XX
Limited (LSE:CPX) will introduce a wireless power module reference design
combining Powercast's RF energy-harvesting technology with a CAP-XX supercapacitor
to create a perpetual, battery-free power source for wireless sensors commonly
used in environmental monitoring, building automation, industrial controls and
other condition monitoring systems.
Low-power energy harvesting can supply the average power required by many
sensor-based systems, but cannot provide the peak power needed to collect and
transmit data over wireless networks such as IEEE 802.15.4 (Zigbee), 802.11
(WLAN) or GSM/GPRS. This is the industry's first reference design using commercial
components that harvests RF energy from low-power radio waves, stores it in
a supercapacitor, and then delivers high power bursts when charged.
The wireless power module reference design integrates a power receiving antenna,
a Powercast Powerharvester™ receiver, and a CAP-XX supercapacitor for
energy storage and peak transmission power. Low-power wireless sensors or RF
modules can be added with simple "two-wire" integration. The module
measures approximately eight inches tall, one inch wide and ¼ inch thick
at the body.
In operation, the design creates a perpetual power supply for fixed or mobile
wireless sensor nodes, such as those located throughout a building, eliminating
the need for batteries or wired power. Powercast's Powercaster™ transmitter,
which powers this reference design, sends radio waves to the Powerharvester
integrated into the module. The Powerharvester converts energy received from
these radio waves into DC power, trickle-charges the supercapacitor, and then
delivers power from the supercapacitor to the wireless sensor. This cycle repeats
as the module receives additional radio waves, which can be sent continuously,
on-demand or on a scheduled basis. This design uses the 915 MHz band, but can
be adapted for other frequencies, or set to harvest environmental radio waves
from TV, radio or mobile phone networks.
The Powercaster transmitter provides controllable, 24 x 7 wireless power, allowing
wireless sensors to avoid using potentially unreliable ambient types of energy
harvesting such as solar or heat.
CAP-XX vice president of applications engineering, Pierre Mars, and Powercast
head of technology platforms, Charlie Greene, will present their collaborative
paper, "Harvesting RF Energy and Powering a Wireless Sensor Node Using
a Supercapacitor," in the energy harvesting session on Monday, May 18 at
the Darnell nanoPower Forum in San Jose, California.
"This 'fit and forget' self-generating power source guarantees that sensors
deployed throughout a building or local area will receive power without batteries
or potentially unreliable environmentally-harvested energy such as solar or
heat," said Mars.
"Wireless sensor networks are increasingly popular, but today are predominantly
powered by disposable batteries," explained Harry Ostaffe, director of
marketing for Powercast. "The RF energy harvester and supercapacitor combination
eliminates the cost and hassle of replacing and disposing of batteries, and
enables wireless sensor networks to scale to thousands of nodes with minimal