Advanced Modeling of Three-Phase and Multi-Three Phase Motor Drives Under Faulty Conditions

The safety and reliability requirements are becoming more and more strict in a number of applications, such as automotive, aerospace and ship propulsion. The canonical models of electric motor drives are developed assuming a healthy condition of the machine, and tend to fail when simulating a fault transient. Therefore, the transient current and torque occurring in case of fault are often hardly estimated and predicted. For this reason, this thesis focuses on developing an accurate simulation model of the motor drives, capable of dynamically covering faulty conditions. This permits to better understanding of the fault dynamics, verifying the motor design, and developing effective control strategies for fault detection and reaction. In the last decade, multi-three-phase electric motor drives have become more and more popular in fault-tolerant applications. Therefore, the developed model was extended from the three-phase motors to the more general case of multi-three-phase machines. SyR-e is an open-source Matlab tool developed for the design and control of electric motor drives. In particular, its library SyreDrive permits automatically generating a simulation model of the designed motor drive in the Simulink or PLECS environment, including the motor control strategy. If Syredrive was originally developed for three-phase motors, a key contribution of this thesis is its extension to the multiphase case. A new method was developed for automatically generating a motor model having an arbitrary number of three-phase sets. This was implemented in the PLECS environment, exploiting a vectorized model of the machine and inverter, which greatly simplifies the graphical interface and facilitates the automatic generation of models. A fundamental chapter of the thesis is dedicated to the simulation of faults, both for the three-phase and multi-three-phase cases, and the evaluation of the motor performance under different fault events. The simulations cover a wide range of fault scenarios, including active short circuits, single switch faults, opening of three-phase groups, and inter-turn short circuits, offering valuable insights into the motors' ability to maintain operability and performance in the presence of anomalies. Additionally, the proposed model and the faulty scenario were validated through Hardware-in-the-Loop (HIL) techniques, providing a platform for testing the drive performance in realistic scenarios. This approach confirms the effectiveness of the presented models. In conclusion, this thesis significantly contributes to the literature on electric drive systems, offering new tools and methodologies for evaluation of the motor performance under faulty conditions. The modeling and simulation strategies developed not only improve the understanding of fault dynamics but also provide a solid foundation for the design of safer, more efficient, and resilient drive systems.