Model-based design of a Vehicle Management Unit and an Electric Retrofit Kit for the reconversion of internal combustion engine vehicles

It is now widely known that purely electric vehicle technology represents one of the most likely technological scenarios for the coming years. However, its full implementation still faces some challenges that have not been completely overcome yet: 1. The cost of a fully electric vehicle, including batteries, is barely below 40,000 euros. 2. The supply chain for components and subsystems is not ready to offer optimized solutions according to automotive standards. 3. There are a lot of vehicles with Euro 3 or Euro 4 emission ratings that, despite being perfectly operational, will no longer be usable in urban centers. Their disposal will still represent a cost. A possible solution to overcome the above limitations is the development of an electrical device, called VMU (Vehicle Management Unit) together with the Electric Retrofit Kit (ERK, which includes a battery, an inverter, a motor and a DC-DC converter) to be adapted to an already existing vehicle as part of a “retrofit” activity that involves the conversion of a polluting vehicle into a purely electric one. The VMU will be able to interact with the components of the ERK to provide them with the proper instructions. This paper aims to apply the Model-based Design approach to the definition of the specifications of the Electric Retrofit Kit, from the initial drafting of the requirements to system simulation. Beginning with a study of the ISO 29148-2018, the paper details the key recommendations and guidelines provided by the standard for the correct and compliant definition of technical requirements. Based on these insights, a requirements document template is developed, following the standard suggestions. The guidelines are then, applied to writing the requirements for the components involved in the implementation of the electrical scheme of the vehicle. Finally, using the template, a finite state machine is designed to represent the behavior of the retrofitted vehicle, implemented in Matlab/Simulink and Stateflow environments.