Belt-Driven Starter-Generator for Future 42-Volt Systems

This paper explores issues related with the design and implementation of belt-driven starter-generators for future 42-V systems. Belt-driven starter-generators can offer many advantages including smooth restarts, high efficiency, and convenient packaging. Future vehicle systems require these characteristics to enable fuel economy functions like “engine off at idle” and “x-by-wire.” Belt-driven starter-generators are often easier to package in contrast with flywheel-mounted systems, which require powertrain modifications and in many cases a longer package. A prototype system based on a belt-driven induction machine mounted on a small, European engine is described in the paper. Test results for both cranking and generation are shown and analyzed. Efficient, high-power generation was confirmed and high-speed (beyond 400 engine rpm) cranking was demonstrated down to the targeted -20°C. The paper also provides comparisons with various engine-starting, machine thermal, and electrical model results.