Ultracapacitors Driving Changes in Electrification

There’s an ongoing shift in the automotive industry to identify and integrate different energy-storage technologies, driven by the electrification of mechanical subsystems. The ultracapacitor already has demonstrated its ability to give vehicles of different sizes a source of regenerative power in tandem with processes typically supported by batteries.

Ultracapacitors differ from batteries by storing energy in an electric field to allow for quick charge and discharge as needed, but they can work alongside batteries in addition to ultracapacitor-only solutions. Those capabilities make ultracapacitors an ideal aspect of automotive electrification moving forward. The conversation seemingly always begins with start/stop capability, but there are additional applications of electrification.

For both OEMs and Tier 1s, one of the great concerns in seeking new uses of electrification, at least in the past, was sacrificing performance when making considerations for fuel economy. Just the same, leveraging developing technologies to improve certain aspects of an automobile remains a critical concern for manufacturers.

While many industry players are exploring the potential of lithium-ion batteries for vehicle electrification, the addition of ultracapacitors for hybrid-electric systems provides another layer of energy-storage advantages, and many manufacturers are looking at building in ultracapacitors up front for future model years. Where Li-ion batteries provide drivers with long-lasting energy and range, ultracapacitors assist with short bursts of high-power activity, such as engine restart after braking.

In late 2014, the U.S. Advanced Battery Consortium announced plans to develop a high-performance hybrid ultracapacitor/lithium-ion battery for stop/start idle elimination microhybrid vehicles with its selection of Maxwell Technologies for a 24-month development contract.

With more than 1 million cars on the road today that use ultracapacitors, such as the voltage-stabilization systems in PSA Peugeot Citroen’s C5 and C4 diesel models, the implementation of ultracapacitors presents new opportunities beyond stop/start down the road. Cars already are using electric turbochargers to perform better, while engineers have integrated active suspension systems. Both of these advancements are chances for ultracapacitors to improve on two features already offering benefits to drivers.

Electric Turbochargers

Downsized turbocharged engines have become more common in newer automobiles, with consumers enjoying the improved fuel economy without sacrificing performance. Ultracapacitors are emerging as an option for electric turbochargers because they can handle the additional power needs and demanding cycle loads to support the electric compressor in the e-turbo without forcing consumers to spend more on fuel.

Stricter emissions standards remain a primary motivation for manufacturers, but consumers are demanding the same. Pre-development programs have started to test the reaches of ultracapacitors, in terms of giving engines an extra lift and diminishing some of the reliance on large-displacement gasoline engines for improved power.

Electric turbochargers have become pervasive. According to Navigant, 75% of Ford gasoline and diesel engines and 85% of Volkswagen engines were turbocharged as of the ’14 model year. Similar installments are under way at Audi and Volvo. Manufacturers have managed to cut engine displacement significantly without losing performance as a result of turbocharged engines. Testing ultracapacitors is the next step in this pursuit of improved performance without a significant reliance on fuel to do it.

Active Suspension      

Active suspension is just one of a number of advancements enabled by the electrification of mechanical subsystems. The process itself, however, necessitates a constant source of power since the system is in use throughout the drive time. Active suspensions use electric actuators to actively lift or lower the vehicle chassis system to improve the riding characteristics. Despite this, the actual energy demand remains low.

Ultracapacitors are garnering attention as a strong power source for manufacturers building active suspension into their vehicles. Firms that have integrated ultracapacitors recognize the advantage of turning road bumps into electricity with a regenerative active suspension. Ultracaps’ long lifecycle makes them an especially attractive option for powering active suspension systems, especially given the additional loads they must bear for other aspects of the vehicle.

Although active suspension will start out in premium model platforms, the demand for greater fuel economy will make any technology that supports it more widely sought by manufacturers. Ultracapacitors accomplish that goal.

The start/stop benefits of ultracapacitors have been enough to warrant their integration into microhybrid systems. There’s more to the ultracapacitor, though, than delivering the restarting power for a car after resting at a stop light, and several OEMs are in the final stages of qualifying ultracapacitor-based systems for additional production programs for the ’16 model year.

The consistently evolving concept of vehicle electrification and, with it the need to manage transient power loads, demands further research into components that can deliver the benefit of better fuel economy without cutting into performance. As testing continues, it’s likely that even more benefits of ultracapacitor inclusion will emerge.

Jens Keiser is senior manager of product marketing at Maxwell Technologies, with responsibilities in product and business development. Follow Maxwell on Twitter: @maxwell_tech