Model-based design of a test bench for electric traction powertrain development

In case of electrified vehicles, both in Battery Electric Vehicles (BEVs) case and in Full-Hybrid or Plug-in Hybrid Electric Vehicles (FHEVs or PHEVs) case, electric motors testing is a crucial phase of the entire final vehicles build-up process. This because tests allow to verify performance and proper work of the final built-up vehicles.To perform tests on electric motors an electric motor test bench has to be taken into account. It, of course, can be considered in two different cases: before electric motors are mounted in vehicles for verifying if they are able to guarantee desired performance once the final vehicles are built-up, or after electric motors are mounted and used in final built-up vehicles to diagnose experienced problems by vehicles. In the first case, the electric motor test bench is used to obtain the characteristic curves of electric motor under test in order to select proper electric motor during the design phase of an electrified vehicle and building-up a vehicle with desired performance, taking also into account costs, dimensions and other physical characteristics, while in the second case the electric motor test bench is used to obtain maps of the electric motor under test in order to verify the electric motor’s behavior on the base of the modifications done.In this thesis activities, the goal is to build-up a test bench for testing electric motors using a Vehicle Management Unit (VMU), like the one used in vehicles for taking actions on the base of data coming from sensors and for managing these data. Instead, in test bench’s case VMU must be able to pilot both brake motor and motor under test in order to reduce costs of control system that is usually used in the Human – Machine - Interface. Moreover, test bench to be implemented must guarantee power recirculation effect such that motors that require huge power (30 – 50 kW) can be tested using small power supplies able to provide a power equal more or less to the dissipated powers by two motors. To accomplish these goals, thesis activities are focused on the use of V- shaped model for modelling all test bench’s components in order to perform simulations with different input parameters and verifying if initial idea is feasible or not before building up physical electric motor test bench. Then, once the model demonstrates initial idea to be feasible, built-up model can be used to obtain corresponding code to be implemented in VMU that will be used to pilot both bench and test motor in the final built-up electric motors test bench. Once code to be implemented in VMU is obtained, it must be tested in order to verify if it works properly or not. To do this SIL testing (Software-in- the-loop testing) must be performed in order to obtain results to be compared with those obtained during MIL testing (Model-in-the-loop testing) where model is adopted to perform test.