A multi-phase variable-speed electric motor with increased constant power regionMANKO, ROMAN (Avtor) Čorović, Selma (Mentor) multi-phase induction motor with a variable number of pole pairsmulti-phase electrically excited synchronous motor with a variable number of pole pairsvariable-speed electric motor with increased constant power regionrotary transformerwireless excitation.Increasingly stringent requirements for energy efficiency and environmental sustainability have driven extensive electrification across a wide range of sectors, including power generation, ground transportation, aviation, and maritime transport. Consequently, the demand for high-performance electric motors and high-power electronic devices for their control has been rapidly increasing. Nowadays, permanent magnet synchronous motors are prevalent in most applications due to their high-power density, high efficiency and compact size. However, the limited availability of rare-earth elements and their price fluctuations have increasingly directed scientific research efforts towards development of novel permanent-magnet-free motor topology concepts and towards innovative improvements of existing electric motor types such as induction motors and electrically excited synchronous motors. This doctoral thesis proposes a novel multi-phase, magnet-free electric motor topology concept based on the implementation of a novel multi-phase winding design. The proposed motor topology concept primarily aimed to improve operational flexibility, enhance efficiency across a wider speed range, and reduce dependence on rare-earth materials, making it a promising solution for next-generation electric drive systems. The scientific research was more specifically focused on the development of a novel multi-phase induction motor and a multi-phase electrically excited synchronous motor with a variable number of pole pairs that efficiently extends the constant power operating region. Within this framework, a new control methodology for the proposed motor designs was also developed. Furthermore, the limitations of existing excitation solutions for electrically excited synchronous motors were analyzed, and the research was directed toward the development of a rotary transformer for wireless power transfer to the excitation winding. The development of the two novel motor concepts (induction motor and electrically excited synchronous motor with a variable number of pole pairs), together with the new rotary transformer design, was based on detailed electromagnetic analyses using finite element method, stator and rotor structure optimization, prototype manufacturing, and validation of the obtained results through experimental investigations.20262026-09-22 14:40:03Doktorsko delo/naloga188400sl