Minimization of the Electromagnetic Torque Ripple of a Synchronous Reluctance Generator Using External Rotor Excitation

Abstract

This paper presents an approach to minimize the electromagnetic torque ripple of a synchronous reluctance generator (SynRG) with a magnetic field created by externally excited rotor coils. The synchronous reluctance machine is widely used in low and medium power systems such as wind power generation and new electric vehicle technologies. This paper proposes a rotor topology with flux barriers and direct current excited coils that reduce the torque ripple and replace the permanent magnets used in other reluctance rotor topologies. First, the initial rotor design, without excitation coils, is optimized to obtain a new rotor structure that reduces the electromagnetic torque ripple. In this work, the optimization of the rotor geometry was achieved by using genetic algorithms and the finite element method to optimize and parameterize the main components of the machine. In the optimized rotor model, an external electronic converter is included to feed the coils positioned between the magnetic flux barriers and the segments formed by the ferromagnetic material of the rotor. Finally, the electrical and magnetic machine variables obtained from implementing the coils into the optimized rotor are compared to the initial rotor structure operating under nominal load conditions to demonstrate the advantage of this topology in minimizing the electromagnetic torque ripple.