Technology Considerations for Belt Alternator Starter Systems

Due to the need for improving fuel economy, reducing tailpipe emissions and the trend towards increasing electrical content in automobiles, hybrid drivetrains are being considered by the automotive industry. In the foreseeable future, in order to address the drive towards hybridization, vehicle manufacturers will begin to use a 42 volt-based architecture in conjunction with an integrated starter and generator system. Depending on the desired power level and allowable changes to the vehicle drivetrain, either an Integrated Starter Generator which mounts between the engine and the transmission or a Belt Alternator Starter (BAS) system which mounts on the accessory belt can be used.

This paper will examine the impact of choosing either a Permanent Magnet (PM) machine or an Induction machine for a BAS application. The impact of the technology on the electric machine design process, power stage implementation, control strategy and overall system design philosophy will be discussed. Test data for both Induction and PM machines will be presented to help underscore the differences.