Oct 26, 2009

General Motors' Two-Mode Hybrid Powertrain Developed With Model-Based Design

Reduces development time by 2 years with math and simulation-based tools from MathWorks.

NATICK, Mass - The MathWorks today announced that General Motors Company (GM) has developed its Two-Mode Hybrid powertrain control system using Model-Based Design. By using math and simulation-based tools from The MathWorks, GM designed the powertrain prototype within 9 months, shaving 24 months off the expected development time. The complex control system is currently in production in the GMC Sierra Hybrid, GMC Yukon Hybrid, Chevy Tahoe Hybrid, Chevy Silverado Hybrid, and Cadillac Escalade Hybrid vehicles.

The Two-Mode Hybrid powertrain is part of GM’s diverse hybrid and electric vehicle program, with multiple propulsion technologies designed to meet global driving patterns and needs. Created to optimize fuel efficiency in both city and highway driving, the Two-Mode Hybrid powertrain combines a conventional engine with two 60-kW electric motors integrated into an automatic transmission, and it integrates with new components such as battery and power electronics.

By adopting Model-Based Design, where the development process centers around a system model, GM engineers increase time savings. Also, by verifying the control system before hardware prototyping and by using production code generated from the controller models, GM has rolled out production vehicles featuring the hybrid powertrain within four years of starting the control system design process. The ability to reuse design information has helped the global development teams foster more efficient communication and reduced response time, eliminating integration issues.

“Model-Based Design helps us work at a higher level of abstraction, allowing us to verify designs early,” said Larry Nitz, GM executive director of hybrid and electric powertrains. “This ability to simulate and correct systems before committing to hardware allows us to try new control strategies virtually, while the use of production code generation accelerates design iterations and eliminates translation errors common in hand coding.” GM also uses Model-Based Design for the powertrain control development of its upcoming plug-in hybrid and advanced engines and transmissions.

“The timeline GM gave itself to design, verify, and deliver the Two-Mode Hybrid to the market was very aggressive and required engineering work that is traditionally done on the road through iterations with prototype hardware to move to the desktop,” said Steve Toeppe, senior manager, automotive engineering at The MathWorks. “GM’s integration of Model-Based Design into its development process—from early verification of specifications, through testing the designs in HIL simulators, and ending on production vehicles—was exciting to watch.”

GM used MATLAB, Simulink, and Stateflow to design the control system architecture and model all the control and diagnostic functions. Real-Time Workshop Embedded Coder provided the capability to generate production code from the models, and Real-Time Workshop and hardware-in-the-loop (HIL) simulators helped verify the control system.