Earth Day: Smart Materials, Smart Power and the Smart Grid

April 21, 2014 by Jeff Shepard

Smart materials are beginning to emerge that will change the way power and energy systems are designed and produced. Piezoelectric energy harvesting is already a well-established commercial technology. It will continue to grow and will be joined by new smart-materials-based devices including synthetic jets, actuators, nonmagnetic transformers, MEMS-based power switching, and more. Smart materials will be an added focus at this year's Darnell Energy Summit (DES '14), to be hosted September 23-25 in Richmond, Virginia. Make an Earth Day resolution to be there.

DES ’14 will be a combined event featuring the Eleventh Darnell Power Forum (DPF '14) + the Sixth Green Building Power Forum (GBPF '14) + the Fifth Smart Grid Electronics Forum (SGEF '14). With a single registration, you will be able to attend any sessions of interest during these simultaneous leading-edge events. Plus you'll have access to the combined Exhibit Hall and will have an opportunity to network with an outstanding group of international experts in a wide range of power electronics, dc building power, micro grids, and smart grid technologies.

Synthetic jets based on smart materials could provide a thermal management breakthrough for next-generation systems. With a piezoelectric diaphragm driven up and down hundreds of times per second by an ac power source, a synthetic jet pulls in the surrounding air (or other fluid) into a chamber and then expels it.

When used with air as the working fluid, a synthetic jet can provide a highly-targeted and high-velocity flow of cooling air. Synthetic jets made using advanced piezoelectric composite materials can be very thin (fractions of an inch) and extremely rugged. Although the mechanism is fairly simple, extremely fast cycling can require high-level engineering to produce a device that will last in industrial applications.

Nonmagnetic transformers are another area of emerging smart materials technology. For example, Face® Electronics, LC of Norfolk, Virginia has developed and patented an extraordinarily powerful piezoelectric transformer (PT) called the Transoner. These electrical energy transmission devices are electromechanical, not electromagnetic. Transoners are useful in applications involving power conversion, power switching, and wide band signal processing.

Unlike the more common Rosen type PTs that are presently on the market, Transoner has many times the power capacity (80W and more) - with superior power density and emit no electromagnetic interference. Transoners have two distinct modes of operation, resonant mode and non-resonant mode.

In the resonant mode, Transoners exhibit high voltage gain and significant power transfer. Useful for power conversion and power switching, these Power Transoners can be designed to be either isolating or non-isolating. In the non-resonant mode, Wide Band Transoner is suitable for telecommunications or signal processing applications from voice to high speed data transmission.

MEMS based power switching could open new opportunities for replacing mechanical and solid-state relays (SSRs). At the GE Global Research Center a group of researchers are advancing MEMS (Micro-Electro-Mechanical Systems) technology to create ultra-small switches that could have an ultra-large impact on system design that will drive mobile devices of the future.

Prototype device testing shows that GE's RF MEMS switch can help enable increased data transfer speeds, enhanced signal quality, longer battery life, and the advanced RF designs required of LTE-Advanced devices. Power switching devices made with GE's Metal MEMS process are capable of handling greater than 1kW in a tiny form factor. For mobile applications, the technology can be scaled down and miniaturized.

The MEMS metal switches, which are no bigger than the width of a human hair, can control the flow of electricity to an array of electrical systems – from high-power devices that use kiloWatts of power, to an ordinary light bulb. Future applications of the technology are far-reaching. Switches are used in everything from hand-held electronics, to industrial equipment to protection devices.

For example, a MEMS-based power switch could be used to provide arc-less circuit protection combining microsecond switching with contact resistance lower that the best SSRs and the capability to handle large amounts of energy at 400-500 Volts.

What separates GE’s MEMS switch from other MEMS technologies is the unique material set developed by GE researchers that allows the switch to operate for billions of cycles under extreme operating conditions, such as elevated temperature, while maintaining extremely low contact resistance. GE has expressed an interest in licensing its power MEMS technology.

Actuators and flow-control devices can also be fabricated with advanced piezoelectric composites. For example, Thunderâ„¢ actuators from Face International Corp. are based on a piezoelectric composite technology originally patented by NASA. Face's trademark Thunder is an acronym for THin Layer UNimorph Ferroelectric DrivER.

An important feature of Thunder actuators is the versatility of operation in addition to the extraordinary large deflections. Thunder elements can be operated in many different ways pertaining to mounting, stacking configuration and voltage application. And the large deflection capabilities mean that Thunder devices can drive large actuation forces.

The method of operation can be chosen depending on the type of application with force and displacement being the two major governing physical quantities. The tabs provided with standard Thunder actuators provide a means for mounting. The method of mounting changes the force and displacement characteristics of these actuators. Thunder actuators produce comparatively higher force together with larger displacement compared to other traditional piezoelectric actuators.

Smart materials for energy harvesting represent another important area of technology development. During the past year, it has become obvious that the energy harvesting (EH) market has not grown as anticipated. There are a variety of reasons for that situation, the primary one being a lack of cost-effective solutions. The incumbent solutions are simply much too expensive to enable mass adoption. That is set to change in a major way in 2014. For example, the impact of the battery-free option for ZigBee Green has already begun appearing in the form of products designed to support the anticipated growth of the market for EH-powered devices.

Texas Instruments has introduced five new next-generation power management integrated circuits that efficiently acquire and manage microwatts (uW) to milliwatts (mW) of power harvested from light, heat or mechanical energy sources. The bq25570, bq25505, TPS62740, TPS62737 and TPS62736 claim the industry’s lowest levels of active quiescent current and enable battery-free operation to wireless sensor networks, monitoring systems, wearable medical devices, mobile accessories and other applications with limited access to power.

And Fujitsu Semiconductor Limited announced the release of two new power management IC products developed to utilize energy harvesting, the MB39C811 dc-dc buck converter and the MB39C831 dc-dc boost converter. Sample shipments for the two new products are scheduled to start in June of this year. The MB39C811 buck converter features a quiescent current of just 1.5µA and achieves world-leading results in ultra-low power operation. Moreover, the MB39C811 represents the world's first simultaneous use of energy generation from both light and vibration using only one power management IC device.

These are only a few of the exciting new technologies to be presented at DES ’14. This year’s event will span the entire range of new technologies for next-generation power and energy system solutions. DES '14 will include discussions of SiC, GaN, GaAs, composites, ferroelectrics, piezoelectrics, and other advanced/smart materials. The application focus will be broad and will include: power conversion, motion control, energy harvesting, energy storage, micro grids, wireless power, smart systems, thermal management, and more. DES '14 will be a combined event featuring the Eleventh Darnell Power Forum (DPF '14) plus the Sixth Green Building Power Forum (GBPF '14) plus the Fifth Smart Grid Electronics Forum (SGEF '14).