Abstract: A method and apparatus are provided for detecting a rotor lock condition in a sensorless permanent magnet synchronous motor. A BEMF observer determines an estimated rotor speed {circumflex over (?)} and a first BEMF voltage value in an estimated rotor-related ?,? reference frame. In addition, a second estimated BEMF voltage value is calculated in a rotor-related d,q reference frame based on at least a first motor constant and an estimated rotor speed {circumflex over (?)}. After generating a BEMF error filter value from the first and second estimated BEMF voltage values and calculating a BEMF error threshold value as a function of the estimated rotor speed {circumflex over (?)} that is subject to a minimum threshold BEMF value, a rotor lock condition is detected based on at least the BEMF error filter value and the BEMF error threshold value.

Abstract: A method and apparatus are provided for detecting a rotor lock condition in a sensorless permanent magnet synchronous motor. A BEMF observer determines an estimated rotor speed {circumflex over (?)} and a first BEMF voltage value in an estimated rotor-related ?,? reference frame. In addition, a second estimated BEMF voltage value is calculated in a rotor-related d,q reference frame based on at least a first motor constant and an estimated rotor speed {circumflex over (?)}. After generating a BEMF error filter value from the first and second estimated BEMF voltage values and calculating a BEMF error threshold value as a function of the estimated rotor speed {circumflex over (?)} that is subject to a minimum threshold BEMF value, a rotor lock condition is detected based on at least the BEMF error filter value and the BEMF error threshold value.

Abstract: A method and apparatus for electric motor thermal management is provided. A thermal model allows estimation of temperatures of an electric motor and determination of a motor overload condition. The thermal model is based on electrical parameters that can be measured in a motor control circuit. An electric motor control method and circuit utilizes a back electromotive force (EMF) measurement circuit, a processor coupled to the back EMF measurement circuit for receiving a back EMF measurement and for calculating a thermal model of the electric motor, the thermal model based on a stator-to-ambient thermal resistance value accounting for a sum of a stator-to-case thermal resistance and a case-to-ambient thermal resistance, and an electric motor driver circuit coupled to the processor for providing drive signals for controlling delivery of power to the electric motor based on the thermal model of the electric motor.