Modelling and Design of systems and components for Hybrid Powertrains The current carbon emission regulations have pushed the search for new systems and strategies to reduce these emissions. One such strategies which achieves lower emissions with a low cost is the ‘’mild hybrid electric vehicle’’. This thesis focuses on modelling a mild hybrid electric vehicle’s powertrain in Simulink/Simscape. Alongside the powertrain model a possible control solution is developed and tested on the developed model. The controller model is initially developed in Simulink and later converted in Stateflow format. After an adequate solution is found, code is generated from the model and the result is validated on a hardware in the loop HIL setup where the controller is transferred to an electronic control unit, while the powertrain model is loaded into a dedicated real-time processor.