Modeling and Validation of a Transmission E-Pump for Application in Hybrid Vehicles

The Electric Pump (E-Pump) is a critical component in the hybrid transmission system. The E-Pump provides flow to maintain a stable line pressure when the engine is in an off state. The main applications of the E-Pump are Park Pawl engagement and disengagement, engine start-stop operation and shadow shifting. A Systems Engineering Approach was followed to develop a medium fidelity plant model for the E-Pump. The developed model was initially tested and validated in the Model in-the loop (MIL) environment. After initial validation, the model was integrated into the overall vehicle model which was then tested on the Software in-the loop (SIL) and Hardware in-the loop (HIL) environments. The model was validated across different platforms and several operating conditions. The basic applications of the E-Pump such as park pawl actuation, engine starting and shadow shifting were validated. The model was later validated using the data, which was acquired on a prototype vehicle run on a dynamometer. The goal was to develop a common model, which could be used across different simulation platforms such as MIL, SIL and HIL. Development of the E-Pump model enabled early testing of critical requirements related to basic functionality of the system which otherwise would have be difficult to test. This in turn accelerated the software development process, which resulted in developing a mature and robust software even before the actual hardware was available. This paper describes the modeling and the verification and validation methods that was used for implementing the E-pump model across several platforms.