Control of idle speed in a hybrid powertrain configuration

1. Field of the Invention The present invention includes an apparatus and a method for controlling the idle speed of a powertrain. The possible idle speed control operating modes detailed are (1) engine-torque-control/motor-speed-control, (2) engine-off/motor-speed-control, and (3) engine-speed-control/motor-torque-control. The engine-off/motor-speed-control mode is used when all conditions to turn the engine off are met. The motor is run at a speed that is determined by the ancillary demands-subject to motor or engine constraints. The engine-torque-control/motor-speed-control operating mode is used when the engine is required to be on to provide torque to various mechanically driven ancillary loads, or to charge the batteries. The engine-speed-control/motor-torque-control operating mode is used when the engine is required to be on because of conditions not related to providing torque to other components.