Interleaved controllers

A system of networked controllers comprising a plurality of controllers according to any one of the preceding claims, configured to:

• receive from each of a plurality of controllers, each controller associated with a respective one of either:
• a plurality of subwindings or a plurality of linked motors, respective values for the first estimator variable;
• combine the values of the first estimator variable into an overall value of the first estimator variable;
• and
• estimate the overall back EMF based on the overall value.

A method of controlling a motor, the motor having a stator with a plurality of subwindings each having a plurality of phase connections for receiving phase voltages, wherein each of the subwindings is electrically insulated from each of the other subwindings, and a rotor comprising a plurality of permanent magnets or energisable electromagnets, the method comprising:

• obtaining, from each of a plurality of control parts associated with respective subwindings, at set discrete time intervals, a plurality of back electromotive force, EMF, readings for each of the respective sub-windings;
• for each control part, using an estimator to estimate an amplitude of a sine wave, a frequency of the sine wave, and a phase of the sine wave;
• estimating a value for an overall back EMF of the motor using the estimated amplitudes, frequencies and phases;
• estimating a commutation event timing based on the overall back EMF;
• and
• providing the commutation event timing to the control parts.