Position observer for electrical machines

摘要

A control system is provided for an electrical motor comprising a rotor, a stator having a plurality of phase windings, and an inverter for applying voltage to the plurality of phase windings so as to cause rotation of the rotor. The control system may be configured to measure a first rate of change of current in a first phase winding, measure a second rate of change of current in a second, different phase winding, calculate a difference between the first and second rate of change of current, and to use the calculated difference to obtain data related to a position of the rotor. The system may be configured to operate in a first control mode when the motor is in a low speed regime, and to operate in a second control mode when the motor is in a high speed regime. When the motor is in a low speed regime the system may be configured to calculate a relationship between flux linkage and current of the stator, and, when operating in the second control mode, to use the relationship to measure an electromotive force, emf, generated by the rotation of the rotor.