Comparison between induction and PM machine for high speed starter-generator applications

An integrated starter/generator is a single device that provides both the electrical starting and alternating operations essential for combustion engines. Starter/generator applications´ requirements include a low speed-high torque motoring mode followed by a wide high speed-constant power region. These conflicting requirements in combination with strict rules and regulations in terms of safety, size, weight, efficiency and power factor constitute the main challenges this application entails. This paper describes a procedure followed to design a high speed starter/generator based on an induction machine drive. Design optimization is performed as a way to emphasize the trade-offs to be made between the performance at different modes of operation and the weight of the machine. Eventually, a comparison with an already available permanent magnet machine designed specifically for the same application is attempted.