Control architecture and method to evaluate engine off operation of a hybrid powertrain system operating in a continuously variable mode

There is provided a method and apparatus to determine operating conditions for a powertrain comprising an internal combustion engine and first and second electrical machines and an electro-mechanical transmission selectively operative to transmit torque therebetween. The method comprises determining a torque output and an operating cost for operating the first and second electrical machines of the hybrid transmission effective to meet an operator torque request when the engine is operating in an engine-off operating state. Determining the torque output for operating the first and second electrical machines comprises executing a predetermined system equation effective to determine motor torque outputs from each of the first and second electrical machines based upon the selected parametric value for the input torque and the operator torque request.