There is an increasing amount of electronics in cars today. Why is that? There are several reasons. First, the growing use of electrical propulsion systems means that the subsystems have to be electronic too. Second is safety. Collision avoidance and navigation systems, for example, are safety related, and it's smart electronics that make them possible. The third reason is efficiency. Electronics are simply more efficient. Replacing hydraulic steering systems with electric-powered systems can save 5-7 percent of fuel. And the fourth reason is that consumers are demanding a lot more gadgetry in their cars, such as phones, high power audio systems, and power functions for seats and mirrors. They're all electronic.
And then, there's the electronics for smart windshield wipers and other functions too. That's right. And you can add active suspension, heated and air-conditioned seating, and audio and visual entertainment systems. Modern high-end cars have several smart boxes to control parking sensors, wipers, and other devices. Next-generation cars will have electronic door-latching systems. In fact, we are working with a Tier One supplier on an electronic door-latching system now that may be in cars two years from now.
Won't these systems—particularly door-latching systems—need some kind of electronic backup? Yes, just like the industrial world requires redundant systems to back up their computer-processing systems. The most likely backup in cars will be ultracapacitors rather than batteries. Batteries don't work well in the cold so you wouldn't want them in doors. Ultracapacitors operate in a broad temperature range, -40C to +65C, they don't require maintenance, and they last a long time.
What's the reason for the long life with ultracapacitors? There are no chemical reactions with an ultracapacitor, so they're highly stable. They can work for many years with minimal change in performance. While battery replacement is considered normal and is expensive, ultracapacitors can last for the life of the system, and there are savings there.
You drew a comparison with industrial power systems, and many of them use distributed architectures. Explain how distributed power applies to automobiles. Distributed power makes systems more robust while cutting cost, weight, and complexity. Central power requires separate wires from the control box to each power device. Distributed architectures distribute power through a few power buses. Control signals also go through common communications buses. Power and signal go through a local distribution node that incorporates intelligent electronic controls and possibly energy storage. The local processor controls local use without running multiple wires long distances to each point of use. Power steering is a great example of the application of distributed power. In a centralized power-steering system there would be a heavy and costly power cable. The voltage drop due to the high current would require that the cable or energy-storage system be oversized. A distributed-power module could be sized for the application and located near the point of use, eliminating the cable.
Smith joined Maxwell, a maker of ultracapacitors, in 1994 as president of its former Balboa Division, and assumed his present position in December 2002. Previously, he had served as president of several Teledyne companies and was general manager of M/A-Com Power Hybrids. E-mail him atRSmith@maxwell.com.