Page 1 of 14 10PFL-0711 CVT-Based Full Hybrid Powertrain Offering High Efficiency at Lower Cost Patrick Debal, Saphir Faid, Laurent Tricoche and Steven Bervoets Punch Powertrain Brecht Pauwels and Kevin Verhaeghe PsiControl Mechatronics Copyright © 2010 SAE International ABSTRACT In 2007 Punch Powertrain started the development of a full hybrid powertrain concept based on its CVT. A performance and efficiency analysis proved that a post-configuration offered the best solution. In parallel to the mechanical and electrical development an advanced, Matlab/Simulink® simulation system was established. A robust powertrain strategy was developed and implemented into the simulation system. Results show a potential of 30% to 70% fuel efficiency improvement depending on the cycle (type approval and real world cycles). A higher saving potential is possible as a plug-in. The fuel efficiency improvement is reached while meeting other important targets. First of all, the powertrain cost premium needs to match the saving. Next to keeping the transmission cost under control the electric drive technology and the batteries are cornerstones of the powertrain development. A dedicated switched reluctance electric motor/generator is developed at a partner. Switched reluctance combines high efficiency and dynamic behaviour with a low cost potential. Special care has been taken to iron out some drawbacks like torque ripple and noise. LiFePO 4 is the preferred battery chemistry. It offers the best combination of performance and cost without the safety risk of classic lithium ion or polymer cells. Additionally, the powertrain size is very restricted. The development team at Punch Powertrain managed to keep the powertrain length, width and height within the size of the conventional counterpart. This enables a straightforward integration into most engine bays. As such, Punch Powertrain offers a fairly easy hybridization path for conventional cars. During the development project the search for auxiliary components was a continuous effort to find affordable components that do not jeopardize the development targets for mass, space and efficiency. For most components a “hybrid compatible” solution was found. The hydraulic pump for the transmission was one exception. A parallel development was initiated during the project. A demonstrator vehicle was built to drive as EV mid 2009 and as full hybrid by the end of 2009. In parallel a second powertrain is built to undergo a series of tests on bench to validate and optimize the powertrain strategy. By exchanging powertrain control modifications between the demonstrator and the test bench driveability will be guaranteed while further optimizing the fuel economy. Experience from both test platforms will be used in
