Patent ID: 6841958

Claim:
A device for controlling an electric motor of the electronic switching type comprising N pairs of poles and P phases, the said device comprising: a coder ( 2 ) intended to be rotated conjointly with the rotor ( 1 ) of the motor, the said coder comprising a main multipole track ( 2 a ) and a revolution pip multipole track ( 2 b ) which are concentric, the said tracks each comprising N identical sectors ( 2 c ) angularly distributed respectively over the entire circumference of the said tracks, the sectors ( 2 c ) of the revolution pip track ( 2 b ) each comprising M angularly distributed singularities ( 2 b 1 ); a fixed sensor ( 3 ) disposed opposite to and at an air-gap distance from the coder ( 2 ), comprising at least three sensitive elements, at least two of which are positioned opposite the main track ( 2 a ) so as to deliver two periodic electrical signals S 1 , S 2 in quadrature and at least one of which is positioned opposite the revolution pip track ( 2 b ) so as to deliver an electrical signal S 3 , the sensor ( 3 ) comprising an electronic circuit able, from the signals S 1 , S 2 and S 3 , to deliver two square digital position signals (A, B) in quadrature which represent the angular position of the rotor ( 1 ) and a revolution pip signal (C) in the form of N*M pulses per revolution of the coder ( 2 ), the M singularities ( 2 b 1 ) being angularly distributed so that the revolution pip signal (C) is arranged so as, in combination with the signals A and B, to define the binary sequences of angular length less than that of a sector ( 2 c ) and which represent the absolute angular position of the coder ( 2 ) on a sector ( 2 c ); a circuit for switching the currents in the phase windings of the motor which comprises 2*P*N switches; a circuit for controlling the switching circuit which is able: when a binary sequence is read, to determine the state of the switching logic of the currents in the phase windings which corresponds to the absolute angular position associated with the said binary sequence; according to the position signals (A, B) detected, to determine continuously the state of the switching logic which is adapted to the angular position of the rotor ( 1 ); to supply the switching signals for the switches which correspond to the state of the logic determined by the revolution pip signal (C) or by the position signals (A, B).