GM Sequel Concept

Press Release

Longer range

Sequel’s 480-kilometer range is made possible by advances in high-pressure storage that enable the vehicle to carry 8 kg of hydrogen, more than double that of GM’s Zafira HydroGen3 fuel cell vehicle. Developed in conjunction with Quantum Technologies (Nasdaq: QTWW), of Irvine, Calif., three lightweight, carbon composite tanks store hydrogen at 700 bars, compared to 350 bars in Hy-wire, Sequel’s predecessor. The larger tanks also enable a better ratio of stored hydrogen mass versus fuel storage system mass.

Within the novel skateboard floor are three cylindrical tanks. The carbon-fiber 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 480-kilometer 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.�

The electrical architecture of the Sequel consists of three systems. A high-voltage system provides power for the drive system, while a 42-volt system supplies the by-wire features. A 12-volt system powers conventional vehicle accessories such as the audio system and interior lighting. A high-voltage lithium ion battery system is an integral component in the Sequel’s propulsion system. It helps power the drive system at certain times, but also stores energy from regenerative braking, and thereby extends range. The lithium ion battery, supplied by Saft, of Bagnolet, France, offers 65 kW of peak power and weighs 65 kg.

Global effort

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.�

Unprecedented Launch, Maneuverability And Stability make Sequel Safe and Fun to Drive

The electric motors reach a total power of 110 kW.

Sequel has taken today’s state-of-the-art, by-wire technologies and integrated them into a vehicle that is not only safe, but is a blast to drive by giving the driver greater control. The by-wire systems use electrical signals and actuators to operate the accelerator, brake and steering, and chassis-damping subsystems.

“This allows it to respond faster and have greater sensitivity, which provides for more precise vehicle control,� said Nick Zielinski, GM vehicle chief engineer, Advanced System Integration.

Sequel’s lower dominant structure has an inherently stable design with 50:50 front/rear weight distribution and a low center of gravity. Sequel also boasts, in addition to anti-lock brakes and StabiliTrak, a unique, all-wheel-drive traction system with front and rear torque control that further enhances vehicle stability and traction.

A transverse-mounted, three-phase, 60-kW electric motor drives the front wheels, and two, three-phase 25-kW electric wheel hub motors drive the rear wheels, resulting in a total power of 110 kW.

“By placing an electric hub motor in each rear wheel, there will be a 42-percent increase in torque when the vehicle begins to accelerate,� said Chris Borroni-Bird, director of GM’s Design and Technology Fusion Group and program director for Sequel. “All of that torque is available instantly and really makes Sequel fun to drive.�

The rear wheel hub motors and the power inverter module for the front electric motor were developed by GM’s Advanced Technology Center in Torrance, Calif.

“Wheel motors are a natural tie-in to all-wheel-drive, and they enable a higher level of traction and anti-skid control, improved steering and enhanced vehicle performance,� said Borroni-Bird.

Sequel’s by-wire technology may revolutionize driving

By-wire sub-systems are housed in skateboard chassis.

The GM Sequel will have enhanced braking, accelerating and handling characteristics by substituting by-wire technology for traditional mechanical systems.

By-wire technology essentially replaces mechanical and hydraulic linkages with electrical wires and actuators. By-wire systems convert driver commands, such as pressing the brake pedal or turning the steering wheel, into signals that actuate an electric motor to carry out the task.

“We have made tremendous progress in the design of by-wire technology, and we will continue to gain confidence in the durability and reliability of by-wire systems with extensive road testing of Sequel,� said Nick Zielinski, GM vehicle chief engineer, Advanced System Integration.

By-wire technology is likely to profoundly change the automotive industry by improving safety, making driving more enjoyable and allowing greater design freedom. It also could simplify maintenance because there are fewer moving parts that can wear out, and it can be more environmentally friendly than conventional vehicles. With steer-by-wire, for example, there is no reservoir of oil-based fluid. Similarly, the brake-by-wire system eliminates the need for brake fluid.

Nearly everything needed to power and control the car, including the hydrogen fuel cell and by-wire subsystems, is packaged into the Sequel’s 11-inch thick (28-cm) chassis structure. Working closely with suppliers such as Visteon, of Troy, Mich., for steer-by-wire; Pacifica Group Limited, of East Bentleigh, Australia for brake-by-wire; and Sachs, of Schweinfurt, Germany, for controlled integrated dampers, GM integrated these and other systems and ensured they work safely and seamlessly with other vehicle systems.

In addition to the chassis systems, by-wire technology also drives the precise, all-wheel-drive traction system. Unprecedented torque control of all wheels is possible because of the single front electric motor and two rear wheel hub motors, developed by GM’s Advanced Technology Center in Torrance, Calif. This system allows instant and almost infinite degrees of torque modulation to deliver the right amount of torque for changing driving conditions.

The ability to recapture braking energy using the front motor and rear wheel motors reduces the overall demand on the vehicle’s battery system. This improves fuel economy and contributes to the Sequel’s 300-mile range. Compared to conventional hybrid electric vehicles, Sequel has electric all-wheel-drive, which provides for more of the braking energy to be recaptured. Sequel’s brake-by-wire system also permits more seamless brake-blending between regenerative braking and conventional braking. This reduces the stopping distance.

In addition to chassis control, the Sequel’s fuel cell powers the climate control system. Sequel has a GM-patented hermetically sealed HVAC (heating, ventilating and air conditioning) system supplied by Mitsubishi Heavy Industries, Ltd., of Tokyo, Japan. In conventional passenger vehicles, the gasoline or diesel engine provides cabin heat and the power for driving the air conditioning system, which typically requires a bulky, in-dash HVAC system. In contrast, the Sequel moves the self-contained HVAC system out of the dash and into the space under the hood normally occupied by the engine. Moreover, by drawing in air through the hood, it allows the front radiators to focus on cooling the fuel cell more effectively so that the vehicle has full power, even on a hot day.

Learning tool

While Sequel represents a significant step closer toward a production hydrogen fuel cell vehicle, its advanced technology is already providing engineers with knowledge on how to extract even greater range and performance from the next generation of fuel cell vehicles. Expected progress in by-wire technology, for example, will enable the steering and brake systems to become considerably smaller and lighter, which will free up space for a larger fuel cell system and smaller battery pack. In addition, continued advances in hydrogen storage will provide the opportunity to lower the floor height and add more power to the fuel cell stack.

“Anything that allows us to reduce the size of the battery pack and storage tanks means more room for a larger fuel cell, which increases vehicle performance,� Zielinski said.

Specifications: GM Sequel