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Hyundai makes room for fuel-cell power
Hyundai has developed a second-generation fuel-cell electric vehicle (FCEV) based on its small Tucson SUV. Compared to the first-generation fuel-cell vehicle, the Tucson FCEV has an extended driving range and incorporates numerous technical advances, including a fuel cell from UTC Fuel Cells that operates at sub-zero temperatures, and a new high-voltage lithium-ion polymer battery. Details of the development work were presented in Monday's "Applications of Fuel Cells in Vehicles" session.

The original Santa Fe hydrogen FCEV was developed in 2000 when the company teamed up with UTC Fuel Cells. In 2002, Hyundai added hybrid technology, and the driving range of the vehicle was extended from 160 to 185 km (100 to 115 mi) using the same amount of hydrogen. But much of the hybrid Santa Fe FCEV trunk space was occupied by the high-voltage dc/dc converter and hybrid battery. The goal for the new Tucson (and Kia Sportage) version was to integrate and improve the technology while maintaining the interior space of the conventionally powered version.

Unlike its predecessor, which featured an under-floor installation, the Tucson FCEV's power plant is located in the front, under the hood. The driving range has been extended to 300 km (186 mi) thanks to its 152-L hydrogen storage tanks. Marginally lighter than its predecessor, the Tucson FCEV also gets an extra 5 kW of fuel-cell power for a peak output of 80 kW. Maximum speed is rated at 150 km/h (93 mph) compared to the Santa Fe's 124 km/h (77 mph). Built with lightweight aluminum body components, the Tucson FCEV has a power-to-weight ratio similar to that of a conventional SUV.

The whole fuel-cell system including hybrid battery and drivetrain are integrated into the vehicle without changing the interior passenger or cargo space. The hybrid battery is designed to have the thickness of a tire so it can be located in the spare-wheel well. For protection from moisture, most of the controllers are placed in the dash panel and under the seats.

Four mounting points are on the front sidemembers for the fuel-cell stack mounting. The Tucson subframe had to be redesigned to mount the driving motor and gear differential unit at three positions.

A crash-test analysis was performed to ensure passenger and hydrogen safety. Even though the hood and side doors were made of aluminum, the results were good. All regulations were met, and the side-impact crash showed even better performance than the conventional vehicle. Much attention was given to the front-crash analysis because of the large fuel-cell stack in the front, which could cause serious impact to the passengers. With proper design of subframe and sidemembers, these concerns were eliminated.

The rear-crash analysis predicted no hydrogen leakage after a 30 mph (48 km/h) crash. The hydrogen tanks were undamaged and the plumbing did not contact any solid body after the crash.

Hyundai's Tucson FCEV is part of the Department of Energy's controlled hydrogen fleet and infrastructure demonstration and validation project.

David Alexander

Mattingly discusses model-based development
By using an implementation model, the Chrysler Group is bypassing the traditional method of giving written specifications as a way to avoid ambiguity and the usual accompaniments of interpretation errors and late engineering changes. And just what is an implementation model?

"This links the feature models to the vehicle's real-world signals, and it enables the interaction between the individual features and begins to bridge from the simulation world to the real vehicle's architecture," William Mattingly, Vice President of Electrical Engineering for the Chrysler Group, said during a Monday afternoon keynote address in the AVL Technology Theater.

Mattingly's message was that, by using model-based development as it relates to the a vehicle's cabin electrical engineering features, it can enable the automaker to better manage increasing complexity while also reducing cost and improving quality.

"Prior to modeling requirements, we used written paper software specifications. These were often vague and subject to interpretation," said Mattingly, noting that some time ago the automaker improved the process by modeling feature behaviors. "Models were built and tested individually, not capturing interaction between features," he said.

Instead of being sidetracked by the limitations, the challenge was to find a way to turn an improved process into a competitive advantage. That meant building quality into the process up front, getting out of the business of writing software and into the business of modeling behavior, and by having suppliers automatically generate software from reliable models by using tools such as Statemate Magnum and I-Logix's Rhapsody in Micro C. The Chrysler Group is also investigating the use of another tool, Altia.

"We model specific vehicle implementation of all of the core features hosted by an ECU," said Mattingly, adding, "We again validate functionality through simulation and now generate test vectors much further down in the process. And prior to the hand off to our suppliers—and much earlier in the process—we validate and get ECU functional buy-off using animation."

The next step is the hand off of a fully validated implementation model to the supplier, which includes all of the features and I/O interfaces. Then the supplier adds its contributions. "The suppliers integrate all of the individual elements, test them, and then deliver the component for final verification prior to vehicle integration," said Mattingly. "We take the test vectors we developed when we validated via simulation and apply them to the finished product." Eventually, the component is integrated into the vehicle, and then the entire vehicle goes through the final validation process.

According to Mattingly, when auto coding becomes more mature and more accepted, suppliers may stop using human beings to write software code. "Human beings should be generating behavior models, and this implementation model is a step toward that process." As for the role of model-based development, "This process works well with state-based systems (i.e., cabin controls), but not with synchronous systems such as powertrain," said Mattingly.

Kami Buchholz