Control of an Electrically Excited Synchronous Motor for a Heavy Truck

Electrically excited motors have become the focus of the world of electric motors due to their efficiency, precise torque control, and versatility across a wide range of speeds and operating conditions. Compared to permanent magnet motors, EESMs do not rely on rare earth materials, making them more suitable for large scale projects. Moreover, EESMs offer high torque at low operating speeds and efficient performance at high speeds making them ideal for use in electrical and hybrid vehicles. However, the advantage of working under varying operating conditions presents its challenges particularly in maintaining stability and robustness. This report addresses these challenges by introducing a control strategy that optimizes the performance of electrically excited synchronous motor (EESM) in an IVECO truck and integrates Maximum Torque Per Ampere (MTPA), flux weakening, and Maximum Torque Per Voltage (MTPV) techniques.The research first developed a simplified linear model of the EESM. The control approach was tested and validated on this linear model to ensure its effectiveness. As a next step the research transitioned to a more complex non-linear model that better describes the actual system. This model was designed using non-linear characteristic maps derived from iterative simulations across different operating conditions. The nonlinear model offers several benefits compared to the linear model, such as providing a more precise representation of the motor’s dynamic behavior under varying load conditions. To make MTPA and MTPV control more efficient, the system uses lookup tables, which contain pre-calculated values. This helps the motor quickly switch between different control modes without needing to perform complex calculations in real time. By using these tables, the control system can handle the motor’s non-linear behavior more easily, without overloading the system’s computational resources. Additionally, custom logic-based functions are used to guide the transitions between MTPA, flux weakening, and MTPV modes, ensuring that the motor operates smoothly and consistently under different conditions.The robustness and stability of the control strategy were validated by altering load conditions and introducing small errors to the system to ensure optimal performance.