Design of Integrated Starter Generator For 42V Automotive Electrical System

Abstract

With this trend, the concept using the single AC machine in the electrical system having the bidirectional power flow gets the attention in the automobile system and the automobile application. There is ISG in the machine having the bidirectional power flow. ISG is an abbreviation for the Integrated Starter Generator. ISG is an electric subsystem in which the functions of the starting engine and the generating electric power are fulfilled by one electric machine onboard automobile, instead of two separated electric machines in a traditional automobile. ISG allows the engine to shut down and avoid idling whenever the automobile is stationary and restart quickly in response to the throttle pedal. This helps reduce the fuel consumption (typically 10% to 25%) and emissions of carbon dioxide and enhance automobile performance. Especially, Belt-Driven ISG of them is excellent in the cost and technology accessibility side in the existing automobile. In this paper, Belt-Driven ISG was designed with IPMSM. It is important to stably satisfy wide operating range of ISG. Motor operation period at low speed is very short in the ISG, so that efficiency of motor mode is not important. On the other hand, ISG mainly operates as the generator at high speed, so that efficiency of generator operation is important. In this paper, these problems can be solved by proposing the Double-Layer rotor in designed IPMSM which has the special design requirement. Results were verified through the finite element analysis.