Belt Driven Alternator and Starter with a Series Magnetized Synchronous Machine Drive

University dissertation from Department of Industrial Electrical Engineering and Automation, Lund Institute of Technology

Abstract: Electric Hybrid Vehicles, EHV, are under development to provide lower fuel consumption levels and minimize the environmental pollution compared to pure Internal Combustion Engine, ICE, driven vehicles. The EHV is more complex and thus carry many more extra parts than the pure ICE based vehicle. Competing against the pure ICE vehicle in the sense of nonexpensive mass production is hard. This thesis is a result of a research project with the goal to develop a complete Belt driven Alternator and Starter, BAS, system for a Stop&Go functionality as a cost-effective hybrid vehicle solution. BAS is based on a Series Magnetized Synchronous Machine, SMSM, which as an adjustable-speed drive system comprises power electronics but excludes permanent magnets. BAS is a rather old concept. It merges two functions, an electric starting motor and an generator, into one single electric machine. It thereby makes the total system lighter and smaller. Furthermore, it facilitates technology leaps on the road towards mass production of electric hybrid vehicles. The developed BAS system is suitable for a midrange passenger vehicle. The Stop&Go functionality provides an ICE turn-off at each vehicle stop. The SMSM is, in addition to generating electricity and starting the ICE, intended to support the ICE with an additional torque when it is assumed beneficial in the sense of reaching low fuel consumption. Topics in the field of power electronics and control of the SMSM that are covered in this thesis are: • Simulations on vehicle basis are performed for optimizing the rated power of the electric machine and its power electronics in the sense of low fuel consumption. • The Series Magnetized Synchronous Machine, SMSM, and the theory lying behind it are presented. The SMSM is carefully investigated both magnetically and electrically. • A simulation model for the SMSM is derived based on the theoretical model that describes the SMSM. • Based on the theoretical model of the SMSM, dedicated current controllers are derived. Other types, as standard PI controllers and a so-called field voltage vector feed forward controller are investigated and simulated for control of the SMSM. • The SMSM is tested in laboratory environment for confirming the behaviour of the derived model of the adjustable-speed drive system including its power electronics.