Review of Switched Flux Wound-Field Machines Technology

This paper explains the state of art of switched flux wound-field machines (SFWFMs). The main advantage of these SFWFMs when compared with induction machines, synchronous machines, direct current machines, etc. is that all the active parts such that armature coil and field excitation coil are located on the stator while the rotor part consists of only iron material without windings. This makes the machine more robust, simple structure, and more suitable to be used for high-speed applications, compared to induction machine which has low mechanical strength, less torque desnity, and low power factor. Theories, numerical and technical literature of different SFWFM are described and analysed. Merits and demerits of different SFWFM structure are discussed. This paper categorized SFWFM topologies on the basis of their structure, flux linkage, cogging torque, average torque, and efficiency.