A control system for a multiphase electric motor includes inputs for a desired torque output of the motor, a measured torque output of the motor, a signal representative of optimal motor efficiency; a signal representative of a measured efficiency of the motor. The output is a two-dimensional DQ control voltage. A torque feedback control loop minimizes error between the desired and measured torque outputs by controlling an angle of the DQ control voltage, and a motor efficiency feedback control loop minimizes error between the optimal and measured motor efficiencies by controlling a magnitude of the DQ control voltage.