CONTROL OF A BRUSHLESS ELECTRICAL MACHINE

摘要

A brushless electrical machine has at least one phase winding which produces torque to drive a load. The control system for the machine is able to vary the flux and current supplied to a phase so as to vary the torque output as a function of the rotor position. The energisation is reduced at particular angles to produce a dip in the torque profile, thus ensuring that, if the drive stalls, it does so at a predetermined position, for example where the losses in the drive are minimised.

主权项

1. A method of controlling a brushless electrical machine to produce an output, wherein the output is a torque or a force, the method comprising:
energising a first phase of the machine in a conduction region between a switch-on point and a switch-off point and in response to an output demand, compensating for a nonlinear relationship between the output of the brushless electrical machine and a current in the first phase to produce a first output between an upper and a lower output limit, respectively higher and lower than the output demand, wherein the first phase is energised to produce the first output between the upper and lower output limits from a beginning of the conduction region to a detent region and from the detent region to an end of the conduction region and to produce a second output at a detent level in the detent region below the lower output limit, thereby favouring stalling of the machine at a detent position within the detent region.