Position sensorless control algorithm for AC machine

A method of controlling an electric motor comprising:

• injecting a high frequency signal into said motor at a first speed;
• processing feedback generated by the injected high frequency signal to determine the position of a rotor in the electric motor at the first speed;
• determining the speed of the electric motor;
• and
• determining the position of the rotor in the electric motor based on back electromotive force at a second speed.

A powertrain for a vehicle comprising:

• an electric motor functionally coupled to at least one wheel in the vehicle;
• an inverter electrically coupled to said electric motor;
• a DC voltage source electrically coupled to said inverter;
• a controller for controlling the output of said inverter to provide electrical current to said electric motor;
• a first motor control module in said controller injecting a high frequency signal into said electric motor to determine the speed and position of the electric motor;
• a second motor control module in said controller detecting the back electro-motive force to determine the speed and position of the electric motor;
• and
• a transition control module in said controller to vary operation between said first motor control module and said second motor control module based upon motor speed.