Real-time simulation of scaled propulsion unit for light electric vehicles

This paper presents the implementation in a real-time simulation the Buckingham Pi theorem scaling method applied to a small surface-mounted permanent-magnet synchronous motor (PMSM) and a low-power battery pack. The goal is the entire system to behave as a light electric vehicle traction motor of 9 kW with a power supply of 652 Wh. In order to determine the optimum size of the motor and the battery pack, this method is a valuable tool. This scaling flexibility can be used to build a relatively low-cost test bench where a propulsion unit can be tested for different motors and batteries, using the same components but with different scaling gains. The scaling method is applied to calculate the appropriate scaling gains. For the PMSM traction motor, the field-oriented control is applied. The models of the control PMSM and the battery are built using MATLAB/Simulink and converted into a dynamic-link library file in order to be uploaded into the real-time processor of the Embedded Controller NI PXIe-8135 2.3 GHz Quad-Core. Different simulation scenarios are applied using NI VeriStand. In LMS Amesim software, a model for the vehicle was built. In the model, the traction motor used is the scaled PMSM and the power supply is the scaled battery. For the complete vehicle, the urban dynamometer driving schedule was applied to test the complete system.