Controller for permanent magnet synchronous motor, control method, and image forming apparatus

Patent metadata

Field	Value
Publication number	US-10141877-B2
Application number	US-201715784347-A
Country	US
Kind code	B2
Filing date	Oct 16, 2017
Priority date	Oct 28, 2016
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

A method for controlling a permanent magnet synchronous motor having a rotor using a permanent magnet, the rotor rotating by a rotating magnetic field caused by a current flowing through an armature is provided. The method includes: presuming, based on a target speed and an estimated speed that is an estimated value of a rotational speed of the rotor, whether or not a step-out occurs; correcting, when it is presumed that a step-out occurs, an estimated angle that is an estimated value of a position of magnetic poles of the rotor; and controlling, based on a post-correction estimated angle that is the estimated angle after the correction, a current flowing through the armature to cause the rotating magnetic field rotating at the target speed.

First claim

What is claimed is:

1. A controller for a permanent magnet synchronous motor having a rotor using a permanent magnet, the rotor rotating by a rotating magnetic field caused by a current flowing through an armature, the controller comprising:
a drive portion configured to feed a current to the armature to drive the rotor;
a speed estimating portion configured to estimate a rotational speed of the rotor based on the current flowing through the armature;
a magnetic pole position estimating portion configured to estimate a position of magnetic poles of the rotor based on an estimated speed that is the rotational speed estimated;
a control unit configured to control, based on an estimated angle that is an estimated value of the position of magnetic poles outputted by the magnetic pole position estimating portion, the drive portion to cause the rotating magnetic field rotating at a target speed indicated in an inputted speed command;
a step-out presuming portion configured to presume, based on the target speed and the estimated speed, whether or not a step-out occurs; and
a correction portion configured to correct the estimated angle when the step-out presuming portion presumes that a step-out occurs; wherein
when the correction portion corrects the estimated angle, the control unit controls, based on a post-correction estimated angle that is the estimated angle corrected by the correction portion, the drive portion to cause the rotating magnetic field depending on the target speed.

2. The controller for the permanent magnet synchronous motor according to claim 1 , wherein the correction portion corrects the estimated angle outputted by the magnetic pole position estimating portion to the post-correction estimated angle.

3. The controller for the permanent magnet synchronous motor according to claim 1 , wherein the correction portion corrects the estimated speed inputted to the magnetic pole position estimating portion from the speed estimating portion in such a manner that the magnetic pole position estimating portion outputs the post-correction estimated angle as the estimated angle.

4. The controller for the permanent magnet synchronous motor according to claim 1 , wherein the step-out presuming portion presumes that a step-out occurs when a speed difference between the target speed and the estimated speed is greater than a threshold that is a difference between the target speed and a predetermined allowable lower limit speed.

5. The controller for the permanent magnet synchronous motor according to claim 4 , wherein the allowable lower limit speed is set depending on a current set value based on which a value of the current flowing through the armature is determined and a load on the permanent magnet synchronous motor.

6. The controller for the permanent magnet synchronous motor according to claim 1 , wherein the step-out presuming portion presumes that a step-out occurs when the estimated speed is reduced in a state where the drive portion is so controlled that the current flowing through the armature reaches an upper limit within a settable range.

7. The controller for the permanent magnet synchronous motor according to claim 1 , wherein the correction portion performs, as processing for correcting the estimated angle, processing corresponding to operation of adding, to the estimated angle, a correction angle depending on a ratio of the estimated speed to the target speed, or, alternatively, processing corresponding to the adding operation.

8. An image forming apparatus for forming an image on paper, the apparatus comprising:
a permanent magnet synchronous motor having a rotor using a permanent magnet, the rotor rotating by a rotating magnetic field caused by a current flowing through an armature;
a carrier roller of which rotation is driven by the permanent magnet synchronous motor to feed the paper;
a controller configured to control the permanent magnet synchronous motor; and
a speed command portion configured to input a speed command to the controller; wherein
the controller includes
a drive portion configured to feed a current to the armature to drive the rotor,
a speed estimating portion configured to estimate a rotational speed of the rotor based on the current flowing through the armature,
a magnetic pole position estimating portion configured to estimate a position of magnetic poles of the rotor based on an estimated speed that is the rotational speed estimated,
a control unit configured to control, based on an estimated angle that is an estimated value of the position of magnetic poles outputted by the magnetic pole position estimating portion, the drive portion to cause the rotating magnetic field rotating at a target speed indicated in the speed command inputted,
a step-out presuming portion configured to presume, based on the target speed and the estimated speed, whether or not a step-out occurs, and
a correction portion configured to correct the estimated angle when the step-out presuming portion presumes that a step-out occurs, and

when the correction portion corrects the estimated angle, the control unit controls, based on a post-correction estimated angle that is the estimated angle corrected by the correction portion, the drive portion to cause the rotating magnetic field depending on the target speed.

9. The image forming apparatus according to claim 8 , wherein the correction portion corrects the estimated angle outputted by the magnetic pole position estimating portion to the post-correction estimated angle.

10. The image forming apparatus according to claim 8 , wherein the correction portion corrects the estimated speed inputted to the magnetic pole position estimating portion from the speed estimating portion in such a manner that the magnetic pole position estimating portion outputs the post-correction estimated angle as the estimated angle.

11. The image forming apparatus according to claim 8 , wherein the step-out presuming portion presumes that a step-out occurs when a speed difference between the target speed and the estimated speed is greater than a threshold that is a difference between the target speed and a predetermined allowable lower limit speed.

12. The image forming apparatus according to claim 11 , wherein the allowable lower limit speed is set depending on a current set value based on which a value of the current flowing through the armature is determined and a load on the permanent magnet synchronous motor.

13. The image forming apparatus according to claim 8 , wherein the step-out presuming portion presumes that a step-out occurs when the estimated speed is reduced in a state where the drive portion is so controlled that the current flowing through the armature reaches an upper limit within a settable range.

14. The image forming apparatus according to claim 8 , wherein the correction portion performs, as processing for correcting the estimated angle, processing corresponding to operation of adding, to the estimated angle, a correction angle depending on a ratio of the estimated speed to the target speed, or, alternatively, processing corresponding to the adding operation.

15. A method for controlling a permanent magnet synchronous motor having a rotor using a permanent magnet, the rotor rotating by a rotating magnetic field caused by a current flowing through an armature, the method comprising:
presuming, based on a target speed and an estimated speed that is an estimated value of a rotational speed of the rotor, whether or not a step-out occurs;
correcting, when it is presumed that a step-out occurs, an estimated angle that is an estimated value of a position of

Assignees

• Konica Minolta Inc

Inventors

• Koide Yasuhiro
• Tachibana Yuta
• Suzuki Daichi
• Yoshikawa Hiroyuki

Classifications

• H02P21/06 Primary

  Rotor flux based control involving the use of rotor position or rotor speed sensors · CPC title

• H02P25/03 Primary

  with brushless excitation · CPC title

• H02P6/18

  without separate position detecting elements · CPC title

• H02P2207/05

  Synchronous machines, e.g. with permanent magnets or DC excitation · CPC title

• H02P6/28

  Arrangements for controlling current (H02P6/10 takes precedence) · CPC title