The ultimate alternative to traditional wiring harnesses is wireless technology. In the near future, energy harvesting and inductive power transfer technology may replace electrical wires, power cords and batteries in a wide variety of applications.
Energy harvesting is a cost-effective process of collecting ambient energy from the surrounding environment, such as light, vibration, heat or radio waves, and converting it into electricity. For example, the technology could be used in medical sensors that monitor conditions, such as body temperature, blood pressure and heartbeats, without batteries or wiring.
Engineers at Fujitsu Laboratories Ltd. recently developed a hybrid energy harvesting device that generates electricity from either heat or light. With this single device, it is possible to derive energy from two separate sources, which previously could only be handled by combining individual devices.
Many other manufacturers are exploring energy harvesting applications. “The technology is intriguing for the automotive industry, because there is a lot of heat, vibration and other energy generated by cars,” says Chris Burns, director of electrical-electronic architecture engineering at Delphi Corp.
Electrical engineers at the University of Michigan recently built a device that can harness energy from vibrations and convert it to electricity with five to 10 times greater efficiency and power than other devices in its class. And, it’s smaller than a penny.
“This new vibration energy harvester is specifically designed to turn the cyclic motions of factory machines into energy to power wireless sensor networks,” says Khalil Najafi, chairman of the Electrical and Computer Engineering Department of the College of Engineering. “These sensor networks monitor machines' performance and let operators know about any malfunctions.
“There are lots of energy sources surrounding us, “ Najafi points out. “To be able to use the energy you harvest, you have to store it in a capacitor or battery. We’ve developed an integrated system with an ultracapacitor that does not need to start out charged.”
Inductive power transfer technology is another technology that may allow manufacturers to use less wiring in the future. During last week’s SAE World Congress in Detroit, Delphi displayed an electric vehicle equipped with a wireless charging system.
“A wireless charging system eliminates the need for a charging cord,” explains Randy Sumner, director of global hybrid vehicle development at Delphi Packard Electrical-Electronic Architecture. “Drivers can simply park their electric vehicle over a wireless energy source situated on the garage floor or embedded in a paved parking spot.
Other wireless charging systems under development make use of traditional inductive charging, which is the same technology used in electric toothbrushes. For instance, a British start-up called HaloIPT has developed wireless charging pads “designed to function beneath asphalt, submerged in water, or covered in ice and snow.”
“In the future, inductive power transfer technology [will be embedded] into the road infrastructure so cars can be charged on the move,” says Anthony Thomson, CEO of HaloIPT. “This dynamic in-motion charging represents the most effective way of solving the range issues faced by electric vehicles today and will significantly reduce battery size requirements.”
However, Delphi’s Sumner claims that competing systems “only work over a limited distance range, require precise accurate parking alignment and can be very large and heavy, making them impractical for widespread use on electric vehicles.
“[Our] system offers more practical and flexible installation than traditional inductive systems, because it uses highly resonant magnetic coupling, a modern technology that safely and efficiently transfers power over significantly larger distances and can adapt to natural misalignment often associated with vehicle positioning during parking,” explains Sumner. “The system transfers energy using an oscillating magnetic field, which is intrinsically safe for humans and animals.”
"This is simply not true," argues Thomson. "All inductive power transfer systems, include HaloIPT's offering, use highly resonant oscillating magnetic fields. Delphi is not doing anything we haven't been doing for 20 years. We have buses in Genoa and Turin using wireless charging and many vehicles around the world, including a Rolls-Royce Phantom Electric that was showcased at the Geneva Motor Show last month. [Our] wireless power system can transfer power over very large gaps."
Delphi has been working with WiTricity Corp., which is marketing a patented technology for wireless energy transfer that was invented by a team of MIT physicists in 2006. In addition to electric vehicles, it’s developing wireless applications for a wide range of consumer electronics, medical devices and military devices. For instance, WiTricity engineers are miniaturizing and packaging the technology so that it can be built directly into products such as computers, telephones, cameras and televisions.
According to Sumner, Delphi’s system will automatically transfer power to an electric vehicle’s battery pack at a rate of 3,300 watts-the same rate as most residential plug-in chargers-and is able to do so with the smallest and lightest modules possible.
“These components are important to minimizing overall vehicle weight and cost, while maximizing the driving range of EVs, a critical selling point for automakers,” Sumner points out. “With the support of automotive manufacturers, this technology can be integrated into the next generation of electric vehicles.”
A World Without Wire?
April 18, 2011