Experimental Characterization of an Integrated Starter/Generator

This thesis presents the characterization of an integrated starter/generator (ISG) based on an interior permanent-magnet (IPM) synchronous machine. The ISG is designed to operate in a hybrid vehicle; mounted to a traditional gasoline engine and coupled directly to the crankshaft. An experimental comparison is made between the design and the working prototype including a detailed description of the machine and the materials used. Theoretical operation and lumpedparameter models (LPMs) that predict its performance are summarized. Results from finiteelement analysis (FEA) are also presented. An automated platform has been built for the purpose of testing the machine and is described in detail. This platform is used to measure mechanical losses, back-EMF, inductance, temperature, and performance while motoring and generating. The methods used for each experiment are described and the results are compared with LPM and FEA predictions. This thesis will show that LPM predictions for q-axis inductance and PM flux linkage match well with FEA and measured results. However, the LPM predictions for d-axis inductance must be revised to include leakage from fringing fields around PM cavities at the ends of the stack, crosscoupling of q-axis flux, and details regarding the saturation of the PM bridges. The impact of these errors on the motoring torque is small because at high current, measurements, LPM, and FEA match fairly well. The impact of these errors on generating output power is substantial, and the ISG is not expected to meet the specifications for generating. Thesis Supervisor: Jeffrey H. Lang Title: Professor of Electrical Engineering, Associate Director of LEES Thesis Supervisor: Thomas Keim Title: Assistant Director of LEES