Advanced control of electrically excited synchronous motor fed by a magnetically integrated current source inverter

This thesis investigates an innovative electric drive architecture that combines an electrically excited synchronous motor with a current-source inverter. While elec trically excited synchronous motors eliminate the reliance on rare-earth permanent magnets and provide an additional degree of freedom through field current regula tion, traditional current-source inverters suffer from the bulky footprint and power losses of the required standalone direct current link inductor. The proposed solu tion addresses this limitation through a magnetically integrated topology, utilizing the motor’s excitation winding directly as the direct current link filter inductor. The work details the mathematical modeling of the machine and the derivation of a constrained maximum torque per ampere strategy tailored to this strictly coupled configuration. Furthermore, it presents the sizing of the passive filter components, the space vector modulation technique, and the complete design of robust digital control loops for stator currents, excitation current, and speed. A significant focus is dedicated to the operation in the constant power region, introducing torque limiting control schemes to maintain stability and maximize efficiency utilizing the inherent voltage boost capability of the current-source inverter. Finally, compre hensive simulations are presented to demonstrate the effectiveness of the proposed control strategies under various dynamic scenarios, including load rejection and regenerative braking.

TThis thesis investigates an innovative electric drive architecture that combines an electrically excited synchronous motor with a current-source inverter. While elec trically excited synchronous motors eliminate the reliance on rare-earth permanent magnets and provide an additional degree of freedom through field current regula tion, traditional current-source inverters suffer from the bulky footprint and power losses of the required standalone direct current link inductor. The proposed solu tion addresses this limitation through a magnetically integrated topology, utilizing the motor’s excitation winding directly as the direct current link filter inductor. The work details the mathematical modeling of the machine and the derivation of a constrained maximum torque per ampere strategy tailored to this strictly coupled configuration. Furthermore, it presents the sizing of the passive filter components, the space vector modulation technique, and the complete design of robust digital control loops for stator currents, excitation current, and speed. A significant focus is dedicated to the operation in the constant power region, introducing torque limiting control schemes to maintain stability and maximize efficiency utilizing the inherent voltage boost capability of the current-source inverter. Finally, compre hensive simulations are presented to demonstrate the effectiveness of the proposed control strategies under various dynamic scenarios, including load rejection and regenerative braking.