Method and device for determining a position of a rotor of a three-phase motor

A device for determining a position of a rotor of a three-phase motor using a field-oriented control system, characterized in that the device comprises:

• processing circuitry configured to perform
• determining, by a proportional-integral controller, a first control voltage vector at a first instant using Park transformed motor currents and reference currents,
• transforming the first control voltage vector using an inverse Park transform,
• summing the transformed first control voltage vector to a regular polygonal voltage pattern, the regular polygonal voltage pattern being applied during a given duration, the regular polygonal voltage pattern being composed of at least three subperiods,
• performing a pulse-width modulation from the sum of the transformed first control voltage vector and the regular polygonal voltage pattern, wherein the pulse-width modulation is further performed from a carrier signal,
• controlling the motor with the pulse-width modulation,
• measuring a current at each phase of the motor,
• estimating a position of the rotor from the measured currents and from the regular polygonal voltage pattern, the regular polygonal voltage pattern being composed of plural consecutive subperiods, each subperiod being equal to an integer number times half a period of the carrier signal, and starting at one extremum of the carrier signal, and
• determining, at a second instant, a second control voltage vector from the measured currents and from the estimated position, the time between first and second instants being upper than or equal to the given duration.