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Analytical models of electric machinery often utilize Carter's coefficient to account for the increased airgap reluctance due to flux entering the sides of the stator teeth. In this letter, a modified coefficient is proposed to account for wide stator slots, wherein a component of flux directly enters the stator backiron. The proposed coefficient is implemented in an analytical model of a wound rotor synchronous machine and is validated using twodimensional (2-D) finite element analysis.

In this research, six hybrid machine topologies, utilizing both a field winding and permanent magnets, are investigated for fixed-speed dc generation. The hybrids are compared with the wound-rotor and permanent magnet synchronous machines. To this end, analytical system models are utilized to predict machinerectifier behavior. A general approach used to develop the machine models is discussed; the rectifier and filter models are also presented. The system models are used in a multi-objective design process to establish the tradeoff between overall mass and loss. Detailed losses, geometries, and rectifier waveforms obtained from the design studies are presented for four of the machine types.

Optimization-based design of electric machinery over a large design space requires the use of computationally efficient models to predict machine behavior. In this research, an analytical design model is developed for wound rotor synchronous machines, a key technology for power generation. The model is designed to be used in a rigorous multi-objective optimization algorithm, providing the trade-off between competing mass and loss objectives. A formalized approach is presented to calculate the field distribution, as well as qd-axis model parameters, terminal quantities, loss, and developed torque from design data containing material properties, stator and rotor geometries, and winding layout. The calculated parameters include resistances, inductances, and the back-EMF of the machine. The model is verified using finite element analysis and hardware experiment.