Motor control apparatus for sensorless motor, and image forming apparatus

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.

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.

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 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.

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 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.