Cold Starting Performance of a 42-Volt Integrated Starter Generator System

Over the next several years, vehicle manufacturers will begin to use a 42 volt based system to integrate the starter and generator into one unit known as an integrated starter-generator (ISG). The ISG and its associated electronics and battery pack form a system that has the ability to perform torque smoothing of the driveline, electrical launch assist, regenerative braking, high power generation, engine stop/start, and other features. One of the important tasks to be performed by the ISG is starting the internal combustion engine under extremely low temperature conditions. Traditionally, the 12-volt cranking motor has performed this solitary task over the last sixty years. The ISG system is capable of incorporating the cranking motor task and must be designed to perform this function over the full automotive temperature range. The cold starting requirements have a great influence on the design of any ISG system.

This paper will examine how the cold starting requirements affected the design of the Delphi Energen10^® ISG system. Test results performed at -29 degrees centigrade for the cranking of a gasoline 4.0 liter, V-6 powertrain are presented. A discussion of the electric motor control strategy used during the cold starting events with an ISG system is also included.