A method of controlling an electrical machine that includes selecting an edge of a rotor-position signal as a reference edge and commutating a phase winding of the electrical machine at times relative to the reference edge. The rotor-position signal has at least four edges per mechanical cycle, each of the edges being associated with a respective zero-crossing in back EMF or minimum in inductance of the phase winding. The angular position of at least one of the edges relative to its respective zero-crossing or minimum is different to that of the other edges. The reference edge is then selected from the edges such that the angular position of the reference edge relative to its respective zero-crossing or minimum is the same with each power on of the electrical machine. Additionally, a controller and control system that implement the method.