Pulse-controlled electronically commutated motor

• US 6,741,048 B2
• Filed: 09/26/2002
• Issued: 05/25/2004
• Est. Priority Date: 09/26/2001
• Status: Expired due to Fees

• Current Assignee: SNR Roulements
• Original Assignee: SNR Roulements
• Inventors: Desbiolles, Pascal, Nicot, Christophe, Friz, Achim
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US10/254,765
• Publication Number:
  US 20030059212A1
• Time in Patent Office: 607 Days
• Field of Search: 318/138, 318/254, 318/439, 318/602, 318/605, 318/700, 318/720, 318/721, 318/722, 318/724
• US Class Current: 318/400.37
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position

Abstract

The invention relates to an electronically commutated motor (1) comprising P phases and N pairs of poles, in which a circular multipole encoder (12) is associated with the rotating ring (6a) of an anti-friction bearing (6), said encoder (12) comprising a main multipole track (12a) and a multipole commutation track (12b) comprising 2*P*N singularities (12b1-12b6) equidistributed angularly and a control device comprising a fixed sensor (15) capable of delivering square digital signals A, B in quadrature and a digital signal C in the form of 2*P*N pulses per revolution of the encoder (12), a circuit for commutating (20) the currents in the phase windings of the motor (1) and a control circuit (21) for the commutation circuit (20).

Claims

1. An electronically commutated motor (1) comprising P phases and N pairs of poles, said motor comprising:

a rotor (2) having the N pairs of poles and a stator (3) having P coils formed respectively from a phase winding, said rotor (2) being mounted able to rotate inside the stator (3) by means of at least one anti-friction bearing (5, 6), said anti-friction bearing (5, 6) comprising a fixed ring (5b, 6b) and a rotating ring (5a, 6a) associated with the rotor (2); and

a device for controlling the commutation of the current between the phases of the motor (1);

said motor (1) being characterised in that;

a circular multipole encoder (12) is associated with the rotating ring (6a) of an anti-friction bearing (6), said encoder (12) comprising a main multipole track (12a) and a multipole commutation track (12b) comprising 2*P*N singularities (12b1-12b6) equidistributed angularly, the main (12a) and commutation (12b) tracks being concentric on the encoder (12); and

the control device comprises;

a fixed sensor (15) disposed opposite and at air gap distance from the encoder (12), said sensor (15) comprising at least three sensing elements, at least two of which are positioned opposite the main track (12a) so as to deliver square digital signals A, B in quadrature, and at least one of which is positioned opposite the commutation track (12b) so as to deliver a signal C in the form of 2*P*N pulses per revolution of the encoder (12);

a circuit for commutating (20) the currents in the phase windings of the motor (1) having 2*P*N switches (T1-T6);

a control circuit (21) for the commutation circuit (20) which;

from the signal C supplies commutation signals for the switches (T1-T6); and

from the signals A, B and according to a first current set point (I*) defines a second current set point (Iref) which controls the current (Im) supplying the phase windings of the motor (1).

2. A motor according to claim 1, characterised in that the sensor (15) is associated with the fixed ring (5b) of the anti-friction bearing (5) having the encoder (12).

3. A motor according to claim 2, characterised in that the control circuit (21) comprises a regulation loop controlled by the second current set point (Iref) originating from an electronic circuit (22), said control circuit (21) being capable of modulating the commutation signals in terms of width and duration by means of an AND logic function (26).

4. A motor according to any one of claims 1 to 3, characterised in that the control circuit (21) comprises a microprocessor (25) integrating at least one commutation logic for the commutation circuit (20).

5. A motor according to any one of claims 1 to 3, characterised in that the encoder (12) is formed from a multipole magnetic ring on which there are magnetised a plurality of pairs of equidistributed North and South poles (14) with a constant angular width so as to form the main track (12a) and commutation track (12b), a magnetic singularity (12b1-12b6) being formed from two pairs of poles which are different from the others.

6. A motor according to claim 5, characterised in that the sensing elements are chosen from amongst the group comprising Hall effect sensors, magnetoresistors and giant magnetoresistors.

7. A motor according to claim 6, characterised in that the sensor (15) comprises a plurality of aligned sensing elements which are disposed opposite and at air gap distance from the main track (12a).

8. A motor according to any one of claims 1 to 3, characterised in that the encoder (12) is formed from a target on which the reference (12a) and commutation (12b) tracks have been etched so as to form an optical pattern analogous to a multipole magnetic pattern, the sensing elements then being formed from optical detectors.

9. A motor according to claim 8, characterised in that the sensor (15) comprises a plurality of aligned sensing elements which are disposed opposite and at air gap distance from the main track (12a).

10. A motor according to claim 1, characterised in that the sensor (15) comprises an interpolator increasing the resolution of the output signals.

11. A motor according to claim 1, characterised in that the sensor (15) is integrated in an ASIC type circuit.