Topologies for future automotive generators. Part I. Modeling and analytics

This paper compares the relative suitability of four different alternator topologies for use in an advanced automobile electrical system. The four candidate topologies are: the salient-and non-salient-pole wound-field synchronous alternators, the Lundell alternator, and the homopolar inductor alternator. The analysis is made with the alternator utilizing a switched-mode rectifier that enables load matching for optimal power transmission. This paper models and compares the alternators using hand calculations. Lumped parameter models of each of the four alternators are derived. The output power and efficiency of each machine is evaluated when utilized with a switched-mode boost rectifier and operating at the load matched condition. A direct mathematical comparison of the sizing equations for the four classes of machines is offered. Based on the analysis, the Lundell alternator has the highest power output and efficiency when compared at the same dimensions and field ampere turns excitation. Part II will cover a more detailed and accurate cost optimization of the four alternators while subject to the constraints and requirements of future automobiles.