MIT researchers have developed a power converter that works over a wide range of currencies and reduces resting power consumption by 50 percent, making it well-suited for the power needs of the Internet of Things (IoT) devices, they said.
At the International Solid-State Circuits Conference in earlier this year, engineers from MIT’s Microsystems Technologies Laboratories (MTL) demonstrated a new power converter that maintains its efficiency at currents ranging from 500 picoamps to 1 milliamp, a span that encompasses a 2,000,000-fold increase.
Power converters take an input voltage and convert it to a steady output voltage. The range in currents of the researchers’ converter is dramatically different than the range of a typical power converter, which is generally in a narrow range of currents. This wide range provides more flexibility for the power considerations of IoT applications, researchers said.
“A large number of IoT applications are severely energy constrained, and long lifetimes are achieved through duty cycling,” explained Anantha Chandrakasan, head of MIT’s Department of Electrical Engineering and Computer Science. “Power-hungry components like radios are used infrequently, while other components like sensors and ADCs are turned on more frequently, and overall the device is in a “sleep/standby” mode for most of the time. Thus, the current consumption can vary by many orders of magnitude. This calls for efficient operation of converters over wide current ranges.”
This idea is manifested in the IoT in sensors, for example. The sensors themselves operate at very low power so they can work for months or even longer without a battery change, or on harvested energy. But though they may stay on standby power and only “wake up” to gather information or take a measurement, they also likely will have to communicate with, for example, a distant radio receiver to transmit information, which would require a larger current. In short, this range of activity means they will be drawing on a wide range of electrical currents.
|MIT researchers have developed a power converter that works over a wide range of currencies and reduces resting power consumption by 50 percent, making it well-suited for the power needs of the Internet of Things. (Source: MIT)|
The converter developed by the researchers, then, will allow engineers to increase battery life of IoT systems by efficiently using the deep-sleep modes of the various components, said Arun Paidimarri, a postdoc at MIT’s Microsystems Technologies Laboratories when the work was conducted. Paidimarri, also first author on a paper about the researcher delivered at the conference, is now working at IBM Research.
“Quiescent power is the ‘standby power’ of the converter itself, and reduction of this is important to support ‘deep-sleep’ modes of IoT systems,” he explained. “Wide dynamic range and low quiescent powers are also important for energy-harvesting environments with wide variations in available power.”
Indeed, the new converter improves the current range supported by a factor of 10 and reduces the quiescent power two times over research prototypes and 1000 times over commercial, researchers said. This will help IoT systems maintain efficiency across their modes of operation. The converter also allows system designers to efficiently traverse wide range of available power in energy-harvesting scenarios, Chandrakasan and Paidimarri said.
Researchers plan to continue their work not only to push the possibility of power converters, but also to combine their current work with advances in radios, processors, and sensors to build a full IoT system, they said. “A converter is just one piece of the IoT puzzle,” Chandrakasan said.
Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 15 years. She currently resides in a village on the southwest coast of Portugal.