General Motors Reinvent the Automobile with Sequel

General Motors next-generation fuel cell power system helps Sequel achieve a 300-mile range and 0-60 mph acceleration in less than 10 seconds, while emitting only water vapour.

"Sequel is the first fuel cell vehicle in the industry that delivers the range and performance people expect from their current vehicles, bringing us that much closer to commercialization," said Byron McCormick, executive director of GM's Fuel Cell Activities.

The fuel cell power module consists of the actual fuel cell stack, the hydrogen and air processing subsystems, the cooling system and the high-voltage distribution system. This power module delivers 73 kW of high-voltage power for the electric traction motors, as well as auxiliaries like HVAC (heating, ventilation and air conditioning), by-wire electronics and the battery.

"The system design has evolved and the components are becoming simpler, which is helping drive down the cost of technology and bringing us one step closer to reality," said Daniel O'Connell, head of GM Fuel Cell Product Engineering in Honeoye Falls.

Hydrogen introduced into the fuel cell is now directly converted to electric power to drive unprecedented torque control of all wheels. The two rear wheel hub motors including two inverters, as well as the power inverter module for the front electric motor, are developed by GM's Advanced Technology Center in Torrance, Calif. A high-voltage, lithium ion battery system provides extra power to the three electric motors during acceleration. It also stores power regenerated during braking to help extend the vehicle's overall mileage range.

Engineers at a GM fuel cell facility in Mainz-Kastel, Germany, integrated the fuel cell propulsion system into the vehicle package. The engineers linked the drive motor development with the rest of the system for a complete, vehicle-level, system solution. This led to an increase in the overall efficiency. It makes more power with less hydrogen, improving the performance and day-to-day operation.

GM's next-generation fuel cell also uses a new air intake system that is more efficient, quieter and lighter than its predecessor. The fuel cell stack, along with the cylindrical hydrogen storage tanks, is housed in a unique "skateboard" floor. Additional radiators are located under the Sequel's hood, directly behind the headlights, and in the rear of the vehicle, behind the taillights. These necessary design features help pull heat away from the fuel cell system, allowing Sequel to operate in hotter ambient temperatures.

"A fuel cell system is more efficient than an internal combustion engine, but its energy conversion is totally different and requires much more heat to be removed via the coolant," said Lothar Matejcek, project manager, GM Fuel Cell Activities, Mainz-Kastel. "With its three openings in the front, the extra opening for the HVAC and the two additional openings in the rear, you can easily recognize that Sequel was designed for heat rejection. We expect excellent performance at high ambient temperatures, typical of what you would experience in the desert."

Within the novel skateboard floor are three cylindrical tanks. The carbon-fibre material, supplied by Toray Industries, of Tokyo, Japan, is strong and wraps the all-composite tanks. It provides a storage tank that is lighter than comparable metal tanks. The all-composite tanks have been validated to extremely stringent safety and performance standards representing harsh operating environments.

"Our skateboard chassis with the three-tank design is an excellent approach to providing a vehicle with a 300-mile vehicle range, without compromising overall interior and trunk space for the customer," said Chris Borroni-Bird, director of GM's Design and Technology Fusion Group and program director for Sequel. "Hydrogen storage technology will continue to evolve and, as improvements are made, we will translate this into greater range and smaller packaging designs."

Hundreds of GM engineers and researchers and nearly 200 suppliers around the world have contributed to the technology infused in the Sequel's fuel cell power module and propulsion system.

"The giant strides in efficiency and production viability, as seen in Sequel, simply would not have been possible without this large network of capabilities," said McCormick. "Bringing these great minds together for such an important cause demonstrates GM's commitment to fuel cells."

Publication Date: 14/01/2005

WWW Link: http://www.gm.com

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