PMSM rotor angle identification
View Patent ↗A method and a control device for identifying the angle and polarity of the rotor of a permanent magnet synchronous motor (PMSM), the motor including a stator, including windings and a rotor including at least two permanent magnets. The method includes the steps of determining the rotor d-axis direction by supplying a stator voltage vector pulses to the motor terminals at at least two different stator angles, measuring the phase current at each angle, and determining rotor d-axis position based on motor inductance value in each stator angles calculated from the measured values and determining the rotor d-axis polarity by supplying a current vector to the motor terminals at the q-axis direction, and determining the magnet polarity by observing the direction of the rotor rotation during the test pulses.
1. A method for identifying the angle and polarity of the rotor of a permanent magnet synchronous motor (PMSM), controlled by a frequency converter, the motor comprising a stator, including windings and a rotor comprising at least two permanent magnets, wherein the method comprises:
determining the rotor d-axis direction by supplying stator voltage vector pulses to the motor terminals at at least two different angles, measuring the phase current at each angle, and determining the rotor d-axis direction based on motor inductance values in each stator angle, which inductance values have been calculated from the measured values, and
determining the rotor d-axis polarity by supplying a torque producing current vector to the motor terminals at the q-axis direction, and determining the magnet polarity by observing the direction of the rotor rotation during the test pulses.
2. A method according to claim 1 wherein stator voltage vector pulses for determining the rotor d-axis direction are AC voltage.
3. A method according to claim 2 wherein the polarity determination starts by setting the stator current vector at the q-axis direction, thus producing rotor rotating torque, which torque is increased to a predefined level and when the predefined torque level is reached, the predefined torque level is held for a predefined time.
4. A method according claim 2 wherein the polarity of the rotor is identified on the basis of a small rotor rotation, e.g. around 2 mechanical degrees.
5. A method according to claim 2 wherein the rotor polarity identification is performed before starting the motor.
6. A method according to claim 1 wherein stator voltage vector pulses for determining the rotor d-axis direction are DC voltage pulses.
7. A method according to claim 6 wherein the polarity determination starts by setting the stator current vector at the q-axis direction, thus producing rotor rotating torque, which torque is increased to a predefined level and when the predefined torque level is reached, the predefined torque level is held for a predefined time.
8. A method according claim 6 wherein the polarity of the rotor is identified on the basis of a small rotor rotation, e.g. around 2 mechanical degrees.
9. A method according to claim 6 wherein the rotor polarity identification is performed before starting the motor.
10. A method according to claim 1 wherein the polarity determination starts by setting the stator current vector at the q-axis direction, thus producing rotor rotating torque, which torque is increased to a predefined level and when the predefined torque level is reached, the predefined torque level is held for a predefined time.
11. A method according to claim 10 wherein the current vector supply to the motor is terminated before a predefined time if the rotor rotation angle exceeds a threshold limit.
12. A method according claim 11 wherein the polarity of the rotor is identified on the basis of a small rotor rotation, e.g. around 2 mechanical degrees.
13. A method according to claim 10 wherein the torque is ramped to an opposite predefined value and held for a predefined time if the threshold limit of the rotation angle is not reached before the predefined time has elapsed.
14. A method according claim 13 wherein the polarity of the rotor is identified on the basis of a small rotor rotation, e.g. around 2 mechanical degrees.
15. A method according claim 10 wherein the polarity of the rotor is identified on the basis of a small rotor rotation, e.g. around 2 mechanical degrees.
16. A method according to claim 10 wherein the rotor polarity identification is performed before starting the motor.
17. A method according to claim 1 wherein the polarity of the rotor is identified on the basis of a small rotor rotation, e.g. around 2 mechanical degrees.
18. A method according to claim 1 wherein the rotor polarity identification is performed before starting the motor.
19. A control device of a permanent magnet synchronous motor (PMSM), the motor connected to the control device and motor comprising a stator, including windings and a rotor comprising at least two permanent magnets, wherein
the control device is configured to carry out the methods steps of claim 1 .
20. A control device according to claim 19 , wherein the control device is a frequency converter.