Motor control apparatus for sensorless motor, and image forming apparatus

Patent metadata

Field	Value
Publication number	US-9431940-B2
Application number	US-201414547267-A
Country	US
Kind code	B2
Filing date	Nov 19, 2014
Priority date	Nov 26, 2013
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

A motor control apparatus includes a supply unit to supply a current for excitation to a plurality of coils of a motor, a first detection unit to detect a physical quantity which varies depending on a change in inductance of at least one of the plurality of coils, and a determination unit to determine a rotational position of a rotor of the motor. A control unit controls the rotational position of the rotor of the motor based on a determination result by the determination unit, and a second detection unit detects an inducted voltage of each of the plurality of coils. The determination unit also determines the rotational position of the rotor based on the detected physical quantity when the rotor is at rest and when a rotational speed of the rotor is smaller than or equal to a predetermined value, and determines the rotational position of the rotor based on the detected induced voltage when the rotational speed of the rotor is greater than the predetermined value.

First claim

What is claimed is:

1. A motor control apparatus comprising:
a supply unit configured to supply a current for excitation to a plurality of coils of a motor;
a first detection unit configured to detect a physical quantity which varies depending on a change in inductance of at least one of the plurality of coils;
a determination unit configured to determine a rotational position of a rotor of the motor based on the physical quantity detected by the first detection unit;
a control unit configured to control the rotational position of the rotor of the motor based on a determination result by the determination unit, and
a second detection unit configured to detect an induced voltage of each of the plurality of coils, wherein
the determination unit is further configured to determine the rotational position of the rotor based on the physical quantity detected by the first detection unit when the rotor is at rest and when a rotational speed of the rotor is smaller than or equal to a predetermined value, and determine the rotational position of the rotor based on the induced voltage detected by the second detection unit when the rotational speed of the rotor is greater than the predetermined value.

2. The motor control apparatus according to claim 1 , wherein
the determination unit is further configured to determine the rotational speed of the rotor based on the induced voltage detected by the second detection unit.

3. The motor control apparatus according to claim 1 , wherein
the physical quantity detected by the first detection unit is a rise rate of a current flowing through the coil.

4. The motor control apparatus according to claim 3 , wherein
the first detection unit is further configured to measure the rise rate of the current flowing through the coil by measuring a value of the current after a predetermined period of time has elapsed since application of a voltage to the coil.

5. The motor control apparatus according to claim 4 , wherein
the period of time during which the first detection unit applies a voltage to the coil is a period of time which the rotor is not rotated.

6. The motor control apparatus according to claim 1 , further comprising:
a storage unit configured to store information indicating a relationship between the rotational position of the rotor and the physical quantity detected by the first detection unit,
wherein the determination unit is further configured to use the information stored in the storage unit to determine the rotational position of the rotor.

7. The motor control apparatus according to claim 6 , further comprising:
a measurement unit configured to measure the physical quantity detected by the first detection unit for each rotational position of the rotor, to generate information indicating a relationship between the rotational position of the rotor and the physical quantity detected by the first detection unit, and to cause the storage unit to store the generated information.

8. The motor control apparatus according to claim 1 , wherein
the determination unit is further configured to detect a change in the rotational position of the rotor based on a change in the physical quantity detected by the first detection unit.

9. The motor control apparatus according to claim 1 , wherein
the determination unit is further configured to detect a change in the rotational position of the rotor based on a change in the physical quantity of a predetermined one of the plurality of coils detected by the first detection unit.

10. The motor control apparatus according to claim 1 , wherein
the determination unit is further configured to detect a change in the rotational position of the rotor based on the physical quantity of a predetermined one of the plurality of coils detected by the first detection unit.

11. The motor control apparatus according to claim 1 , wherein
the determination unit is further configured to, when receiving a reference pulse, determine the rotational position of the rotor of the motor.

12. The motor control apparatus according to claim 1 , wherein
the control unit is further configured to, when causing the determination unit to determine the rotational position of the rotor of the motor, set a drive torque to a first torque for the determination, and when controlling the rotational position of the rotor of the motor, set the drive torque to a second torque for movement which is greater than the first torque in order to move the rotor of the motor.

13. The motor control apparatus according to claim 12 , wherein
the control unit is further configured to, after moving the rotor of the motor, when causing the determination unit to determine the rotational position of the rotor of the motor again, change the drive torque from the second torque to the first torque.

14. The motor control apparatus according to claim 1 , wherein
the control unit is further configured to cause the determination unit to end the determination when the rotor of the motor has been moved to a predetermined position based on the result of the determination by the determination unit.

15. An image forming apparatus comprising:
a motor;
a rotating member configured to be rotated by the motor for formation of an image; and
a motor control apparatus,
wherein the motor control apparatus comprises:
a supply unit configured to supply a current for excitation to a plurality of coils of a motor;
a first detection unit configured to detect a physical quantity which varies depending on a change in inductance of at least one of the plurality of coils;
a determination unit configured to determine a rotational position of a rotor of the motor based on the physical quantity detected by the first detection unit;
a control unit configured to control the rotational position of the rotor of the motor based on a determination result by the determination unit, and
a second detection unit configured to detect an induced voltage of each of the plurality of coils, wherein
the determination unit is further configured to determine the rotational position of the rotor based on the physical quantity detected by the first detection unit when the rotor is at rest and when a rotational speed of the rotor is smaller than or equal to a predetermined value, and determine the rotational position of the rotor based on the induced voltage detected by the second detection unit when the rotational speed of the rotor is greater than the predetermined value.

16. A motor control apparatus comprising:
a supply unit configured to supply a current for excitation to a plurality of coils of a motor;
a detection unit configured to detect a physical quantity which varies depending on a change in inductance of at least one of the plurality of coils;
a determination unit configured to determine a rotational position of a rotor of the motor based on the physical quantity detected by the first detection unit; and
a control unit configured to control the rotational position of the rotor of the motor based on a determination result by the determination unit,
wherein the physical quantity detected by the first detection unit is a rise rate of a current flowing through the coil, and
the detection unit is further configured to measure the rise rate of the current flowing through the coil by measuring a value of the current after a predetermined period of time has elapsed since application of a voltage to the coil.

17. A motor control apparatus comprising:
a supply unit configured to supply a current for excitation to a plurality of coils of a motor;
a detection unit conf

Assignees

• Canon Kk

Inventors

• Kameyama Shigeru

Classifications

• H02P6/182

  using back-emf in windings · CPC title

• H02P6/186 Primary

  using difference of inductance or reluctance between the phases · CPC title

• G03G15/5008

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

• G03G15/80

  Details relating to power supplies, circuits boards, electrical connections · CPC title