Examenspresentation för Katriine Koit och Samuel Sjöstrand

Opponent: Simon Larsson, Johannes Karlsson

Abstract
Volvo Cars are investigating a new propulsion control system for traction and charging. The system uses a wireless control protocol with an update frequency of 1 kHz to control the system and, by that, motor torque. The control system builds on battery cells that can be engaged and disengaged to generate a sinusoidal output wave. A central controller performs the engagement actions and can control the polarity and current of each cell individually at a rate of 1 kHz. During some drive cases, the motor current must be updated with an even higher rate to minimize drivetrain oscillations, improve comfort and ensure safe operation. Developing a faster local control loop is the main objective of the thesis. A battery cell system, therefore, is modeled with a 1 kHz reference input signal from a central controller. A local control loop with an update frequency of 10 kHz is implemented within the main control loop to detect and minimize disturbances in the motor operation. The model is tested at multiple operation speeds and exposed to various disturbances to determine its reliability and response to high-speed faults. The implemented local control loop within the master loop shows an improved system response with quicker response times resulting in decreased deviations from the desired reference signal.

Welcome!

Katriine, Samuel and Torbjörn