The rapid development of modern power electronic techniques has greatly changed the topologies of electric machine designs. Variable Reluctance Machine (VRM) which utilizes a doubly salient structure promises a simple and rugged machine construction, the possibility of high speeds and a high torque-inertia ratio. The mechanism of torque production in a VRM, however, is based on the inductance variations, which immediately represents a conflict between high torque production demand for a VRM and the low cost demand for the drive system. Namely, high inductance results in high DC bus stress of the drive, whereas for the same RMS value, the unipolar current operation of VRM raises the peak phase current to about 40% greater than that of electric machine's using bipolar current control, which further increases the current stress for the drive.; The merit of Permanent Magnet (PM) excitations is its high power density and performance due to the fact that the field excitation Ampere-turns by a wound field winding is replaced by PMs which is almost lossless and has much higher energy density than of copper coils. However, conventional PM structures suffer the lack of field-adjustment, which is the stumbling block for its widespread use, especially for variable speed industrial applications.; In this thesis, a new class of Doubly Salient Permanent Magnet (DSPM) machines is developed and theorized. Ferrite PMs are especially suitable for these designs while high power density and superior performance is still guaranteed.; Doubly salient configurations are used for all the designs in this family, which provides high air gap flux concentration and high performances. Field-adjustment capability is achieved by the arrangements of PMs.; Comprehensive investigations are performed to optimize machine designs. The following methods are key steps to form the analytical loop for designing such machines: (1) Sizing analysis. (2) Finite Element Analysis (FEA). (3) Time domain simulation.; The prototype FWDSPM motor drive system is designed, built, and tested. The results from both analytical and experimental analysis show a high potential for various industrial applications of the new class of DSPM machines.
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