The current electric vehicle market, as well as many other industrial applications, is heavily focused on the application of permanent magnet (PM) machines and induction machines (IM). However the limitations of these two types of electric machines reveal the necessity for further research in the field of electrical machines to substitute the existing types with less expensive, and more fault tolerant machines. The synchronous reluctance machine (SynRM) is a singly excited machine with great potential to replace permanent magnet machines and induction machines in traction, as well as many other industrial applications. The rotor structure is simple and only made of steel laminations, which makes the manufacturing procedure less expensive compared to PM machines and IMs. Moreover the absence of rotor windings and a rotor cage eliminates the rotor copper loss, thus enhancing the efficiency compared to IMs. However, the use of the SynRM has not yet reached the same maturity level of its counterparts and still faces problems like low power density, poor power factor, and limited torque-speed envelope, representing a fertile terrain for research.
The aim of this research is to develop an analytical approach based on the winding function method for modeling, analysis, and design of SynRMs and PM assisted SynRMs. The proposed analytical approach is based on the winding configuration of the machine, and the magnetic characteristics of the rotor topology. It provides insight of the machine’s characteristics, and can be used to apply design modifications on existing SynRMs to improve the performance of future designs. The analytical model is later modified for designing a PM assisted SynRM using AlNiCo magnets, with the aim to improve the power factor and torque density of the regular SynRM.
The self-excitation phenomenon in synchronous reluctance generators (SynRGs) is also investigated and the requirements for the assurance of self-excitation are identified. Therefore in traction applications, and electric vehicles with vehicle to grid (V2G) capability, the possibility of utilizing the onboard SynRM as a power generation unit for emergency situations can be considered. The stand-alone SynRG can also be used as a fault tolerant power generation unit to supply electric power in remote areas.