Investigation of interior permanent magnet offset-coupled automotive integrated starter/alternator

Growing automotive auxiliary electric power requirements have resulted in considerable interest in an integrated starter/alternator (ISA). Initial efforts in this area have been focussed on a direct-drive ISA configuration which offers an appealing degree of mechanical simplification. However, an offset-coupled ISA configuration similar to that used by the conventional alternator has potential for providing a better system solution in some applications, including lower total system cost. This paper first describes the design, construction and dynamometer testing of a concept demonstrator of an offset-coupled ISA using an interior permanent magnet (IPM) synchronous machine. Next, a nonlinear lumped-circuit analysis tool is used to investigate optimized offset-coupled IPM ISA drive designs. Finally, comparisons are presented between an existing direct-drive IPM ISA design and the optimized offset-coupled designs.