Patent ID: 8133151

Claim:
A method for controlling an electro-mechanical transmission operatively coupled to first and second electric machines to transmit power to an output member, the method comprising: determining motor torque constraints for the first and second electric machines; determining battery power constraints for an electrical energy storage device electrically connected to the first and second electric machines; determining an additional constraint on the electro-mechanical transmission; determining a preferred output torque to the output member of the electro-mechanical transmission that is achievable within the motor torque constraints and is based upon the additional constraint and the battery power constraints; controlling operation of the electro-mechanical transmission and the first and second electric machines to achieve the preferred output torque at the output member based upon the motor torque constraints, the additional constraint, and the battery power constraints; formulating mathematical equations representing maximum and minimum motor torque constraints for the first and second electric machines and representing maximum and minimum battery power constraints; formulating a mathematical equation representing the output torque; formulating a mathematical equation representing the additional constraint; transforming the mathematical equations representing the maximum and minimum battery power constraints to equations of concentric circles having respective radii; transforming the mathematical equations representing the maximum and minimum motor torque constraints for the first and second electric machines to equations comprising lines; transforming the mathematical equation representing the additional constraint to an equation comprising a line; and transforming the mathematical equation representing the output torque to an equation comprising a line.