High Fidelity Modeling and HIL Porting of a Hybrid Electric Car Development 2015-26-0011
A hybrid electric powertrain being a complex system requires analysis of all its subsystems to optimally utilize, size components for performance evaluation and control strategy development. An integrated high fidelity model of these can lower development costs, time and achieve the targeted performance while allowing for early redefinition of the system.
A high fidelity model of a sedan car featuring chassis with longitudinal and lateral dynamics, suspension with joints, tires calculating longitudinal & lateral forces during vehicle motion, Engine model with combustion & dynamics of reciprocating and rotating components, Electric motors, Battery system, and gearbox with synchronizers and friction components was developed. Powertrain components were interconnected using 3D rotational flanges. Weight distribution was accomplished by appropriately locating various powertrain components using 3D supporting mounts, which help to study the mount forces as well. The environment definition covers aspects like type of terrain, gradient, ambient pressure, temperature & humidity and path velocities for a drive cycle. A driver model commands steering, accelerating and braking to follow the defined path.
Model scalability could be accomplished in various levels like the engine model could be scaled from Crank Angle based to simple mean value. Thus, emphasizing on particular aspect of simulation like Fuel Economy or emission trials, powertrain dynamics study, etc. Model portability into third party systems provides flexibility in performing HIL simulations. This Dymola model is being used in the HIL testing of control strategies using RT-labs Opal-RT hardware. A major hurdle of computational overrun in real-time was overcome by splitting the plant model and accommodating in 3 different cores of the RT hardware.