Motor control device, image forming apparatus, and method for estimating initial position of magnetic pole of rotor

Patent metadata

Field	Value
Publication number	US-11233471-B2
Application number	US-202016737093-A
Country	US
Kind code	B2
Filing date	Jan 8, 2020
Priority date	Jan 18, 2019
Publication date	Jan 25, 2022
Grant date	Jan 25, 2022

Abstract

A control circuit of a motor control device estimates an initial magnetic pole position of a rotor using an inductive sensing scheme. When estimating the initial magnetic pole position, a drive circuit applies a voltage to a stator winding at each of L electrical angles (L≥5) while changing the L electrical angles. An absolute value of an electrical angle difference of the voltage applied to the stator winding between an i-th time (2≤i≤L) and an i−1st time is 180−360/L degrees or more and 180+360/L degrees or less. An absolute value of an electrical angle difference of the voltage applied to the stator winding between a 1st time for initial position estimation and a last time before starting initial position estimation is 180−360/L degrees or more and 180+360/L degrees or less.

First claim

What is claimed is:

1. A motor control device that controls a three-phase motor of a sensorless-type, the motor control device comprising:
a drive circuit that applies a voltage to each phase of a stator winding of the three-phase motor; and
a control circuit that controls the drive circuit,
wherein:
when the control circuit estimates an initial position of a magnetic pole of a rotor of the three-phase motor using an inductive sensing scheme, the control circuit causes the drive circuit to apply a voltage to the stator winding at each of L electrical angles different from one another while changing the L electrical angles, wherein L is an integer equal to or greater than 5,
an absolute value of a difference between an electrical angle of the voltage applied to the stator winding at an i th time for initial position estimation and an electrical angle of the voltage applied to the stator winding at an (i−1) th time for the initial position estimation is equal to or greater than 180-360/L degrees and equal to or less than 180+360/L degrees, wherein i is an integer equal to or greater than 2 and equal to or less than L, and
an absolute value of a difference between an electrical angle of the voltage applied to the stator winding at a 1 st time for the initial position estimation and an electrical angle of the voltage applied to the stator winding at a last time before starting the initial position estimation is equal to or greater than 180-360/L degrees and equal to or less than 180+360/L degrees.

2. The motor control device according to claim 1 , wherein:
the control circuit performs the initial position estimation in response to a start command for the three-phase motor, and
a timing of applying the voltage to the stator winding at the last time before starting the initial position estimation occurs before the control circuit receives the start command.

3. The motor control device according to claim 2 , wherein:
when the control circuit controls the drive circuit to stop the three-phase motor while gradually reducing a rotation speed of the three-phase motor, the control circuit stores a hold angle at a time when the rotor is stopped, and
the electrical angle of the voltage applied to the stator winding at the last time before starting the initial position estimation is the hold angle.

4. The motor control device according to claim 2 , wherein:
when the control circuit controls the drive circuit to stop the three-phase motor by brake control or free run, the control circuit causes the drive circuit to apply a voltage to the stator winding at a first electrical angle after the rotor is stopped, wherein the voltage has a magnitude sufficient to prevent the rotor from rotating, and
the electrical angle of the voltage applied to the stator winding at the last time before starting the initial position estimation is the first electrical angle.

5. The motor control device according to claim 2 , wherein:
after power supply for operation is started, the control circuit causes the drive circuit to apply a voltage to the stator winding at a first electrical angle, wherein the voltage has a magnitude sufficient to prevent the rotor from rotating, and
the electrical angle of the voltage applied to the stator winding at the last time before starting the initial position estimation is the first electrical angle.

6. The motor control device according to claim 1 , wherein:
for the initial position estimation, the control circuit obtains a detection value of a current of the stator winding, wherein the current is generated by voltage application to the stator winding, and
in accordance with a difference between an electrical angle of the voltage applied at a k th time for the initial position estimation and an electrical angle of the voltage applied at a (k−1) th time for the initial position estimation, the control circuit determines whether to correct the detection value of the current of the stator winding, wherein the current is based on voltage application at the k th time, and k is an integer equal to or greater than 2 and equal to or less than L.

7. The motor control device according to claim 6 , wherein:
when an absolute value of a difference between the electrical angle of the voltage applied at the k th time for the initial position estimation and the electrical angle of the voltage applied at the (k−1) th time for the initial position estimation is not 180 degrees, the control circuit corrects the detection value of the current of the stator winding, wherein the current is generated by voltage application at the k th time, and
when the absolute value of the difference between the electrical angle of the voltage applied at the k th time and the electrical angle of the voltage applied at the (k−1) th time is 180 degrees, the control circuit does not correct the detection value of the current of the stator winding, wherein the current is generated by voltage application at the k th time.

8. The motor control device according to claim 1 , wherein:
the voltage applied to each phase of the stator winding at the i th time for the initial position estimation and the voltage applied to a corresponding phase of the stator winding at the (i−1) th time for the initial position estimation are different in polarity from each other, or at least one of the voltages is zero, and
the voltage applied to each phase of the stator winding at the 1 st time for the initial position estimation and the voltage applied to a corresponding phase of the stator winding at the last time before starting the initial position estimation are different in polarity from each other, or at least one of the voltages is zero.

9. The motor control device according to claim 8 , wherein when a voltage applied at a j th time to one of phases of the stator winding for the initial position estimation is zero, a voltage applied at a (j−1) th time and a voltage applied at a j+1) th time are opposite in polarity to each other, wherein j is an integer equal to or greater than 2 and equal to or less than L−1.

10. An image forming apparatus comprising:
a paper feed roller that takes out a sheet of paper, and a conveyance roller that conveys the sheet of paper taken out;
a printer that forms an image on the conveyed sheet of paper; and
a motor control device that controls at least one of three-phase motors for driving the paper feed roller and the conveyance roller, each of the three-phase motors being of a sensorless type,
wherein:
the motor control device includes:
a drive circuit that applies a voltage to each phase of a stator winding of each of the three-phase motors; and
a control circuit that controls the drive circuit,

when the control circuit estimates an initial position of a magnetic pole of a rotor of each of the three-phase motors using an inductive sensing scheme, the control circuit causes the drive circuit to apply a voltage to the stator winding at each of L electrical angles different from one another while changing the L electrical angles, wherein L is an integer equal to or greater than 5,
an absolute value of a difference between an electrical angle of the voltage applied to the stator winding at an i th time for initial position estimation and an electrical angle of the voltage applied to the stator winding at an (i−1) th time for the initial position estimation is equal to or greater than 180-360/L degrees and equal to or less than 180+360/L degrees, wherein i is an integer equal to or greater than 2 and equal to or less than L, and
an absolute value of a difference between an electrical angle of the voltage applied to the stator winding at a 1 st time for the initial position estimation and an electric

Assignees

• Konica Minolta Inc

Inventors

• Suzuki Daichi
• Kobayashi Yuji
• Yoshida Kazumichi
• Fujimori Harumitsu
• Tachibana Yuta
• Yoshikawa Hiroyuki

Classifications

• H02P6/185 Primary

  using inductance sensing, e.g. pulse excitation · CPC title

• H02P2203/01

  Motor rotor position determination based on the detected or calculated phase inductance, e.g. for a Switched Reluctance Motor · CPC title

• H02P6/22

  in a selected direction of rotation · CPC title

• G03G15/5008

  Driving control for rotary photosensitive medium, e.g. speed control, stop position control · CPC title

• H02P6/085

  in a bridge configuration · CPC title