The topic of my Final thesis was to investigate the working principles and the control strategy of a Permanent Magnet Synchronous Motor (PMSM) from a real application point of view. To be able to see the topic from industrial perspective, I made a comprehensive literature study about electrical motors and their usage.
As a first step in my thesis, the physical background of the motor was investigated and the mathematical model was derived. For driving such motors a 3-phase voltage source inverter is used, utilizing the so-called Space Vector PWM (SVPWM) technique. The whole threefold cascaded PID control loop, including an inner current and outer velocity plus position loops, was designed from control theory aspects. Furthermore I modeled both the mathematical model of the motor and the control system in MATLAB, Simulink and carried out different test cases. After validating the proper functionality, I drew a thorough software architecture design describing the type of modules and their interfaces that need to be realized. Based on that I implemented the complete embedded software in C, using an Aurix TC26x Multicore microcontroller. Applying software-in-the-loop (SIL) tests, the verification of the program was done.
Measurements for certain conditions, such as current, velocity and position step-responses showed that the software was operating as it was desired. Last but not least, a brief outlook was made to the sensorless control strategies, which are still at a research stage and have great potential to improve the efficiency.
With this task I was able to go through an entire motor control design process from scratch and acquired the sufficient knowledge for being able to reproduce the procedure for other motor types and in other environments as well. I found that many research papers rather describe the theoretical and simulation aspects, therefore I focused more on the implementation difficulties that I come across with, suggesting workarounds for such cases.