Examples include a method for controlling a synchronous motor using a variable speed drive. The motor includes a permanent magnet rotor generating a magnetic flux. The method includes applying a predefined electrical command signal to the motor and estimating a motor speed in response to the applying of the predefined electrical command signal. The method also includes reaching a desired estimated motor speed and, in response to reaching the desired estimated motor speed, estimating a parameter related to the magnetic flux of the permanent magnet rotor. The method further includes recording the estimated parameter.