A microprocessor based vehicle control system has been developed as a part of an advanced electric vehicle propulsion system program called ETX-II. The control system provides state-of-the-art drive and brake-by-wire capabilities to help ensure the most safe, smooth and energy efficient operation of the powertrain possible. All driver demands are electronically interpreted, the only mechanical linkage between the driver and the powertrain being the parking pawl cable. The control strategy that has been developed provides torque and shift schedules and closed loop control of torque in response to driver actions. In addition, it has a built-in hierarchy of warning, power limit and complete shut-down type actions in response to an extensive list of possible faults. The control system is also designed to provide significant status and diagnostic information to the driver. The paper describes the control philosophy, strategy, and some of the hardware implementation details. Although developed for an electric powertrain, the simulation based approach used in the control system development is also applicable to IC engine based powertrains.
The ETX-II propulsion system was developed under contract number DE-AC07-85NV10418, funded by the U.S. DOE and partially cost shared by the Ford Motor and General Electric Companies.