A PM Brushless DC Starter/Generator System for a Series-Parallel 2x2 Hybrid Electric Vehicle

A higher power starter/generator system has been implemented for a hybrid electric vehicle using a 20-kW PM brushless DC (BLDC) machine. The PM BLDC machine, coupled to the 1.9 L diesel engine of the vehicle, generates the electrical power to charge the high-voltage energy storage system and to drive an induction machine connected to the rear wheels. It may also use stored energy to start the engine or to assist propulsion during vehicle acceleration. The starter/generator system comprises of the BLDC machine itself, the power electronics, and a control processor, and is integrated into the vehicle via a CAN interface. The control processor responds to torque commands via the CAN bus from the vehicle supervisory controller providing two-quadrant drive operation with Hall-sensor position information. It also monitors current and position sensor signals for fault conditions, and provides a CAN status message summarizing the health of the system. The starter/generator system is an integral part of the series-parallel 2-X-2 architecture that allows multiple modes of hybrid vehicle operation with improvements in fuel efficiency, emissions and performance over conventional hybrid vehicles.