Motor control apparatus, sheet conveying apparatus, image forming apparatus

A motor control apparatus that controls a motor based on an instruction speed indicating a target speed of a rotor of the motor, the motor control apparatus comprising:

• a phase determiner configured to determine a rotation phase of the rotor;
• a speed determiner configured to determine a rotation speed of the rotor;
• and
• a controller having a first control mode in which a value of a torque current component and a value of an excitation current component are controlled so that a difference between the instruction speed and the rotation speed determined by the speed determiner is decreased to control the motor and a second control mode in which constant current is supplied to a winding of the motor to control the motor,
• wherein the torque current component is a current component having a current value represented in a rotating coordinate system based on the rotation phase, which generates torque in the rotor, and the excitation current component is a current component having a current value represented in the rotating coordinate system based on the rotation phase, which affects a strength of a magnetic flux through the winding of the motor, and
• wherein the controller switches a control mode to control the motor from the second control mode to the first control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value lower than a first threshold value to a value higher than or equal to the first threshold value in a state in which the motor is controlled in the second control mode and keeps the first control mode even if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the first threshold value to a value that is higher than or equal to a second threshold value lower than the first threshold value and that is lower than the first threshold value in a state in which the motor is controlled in the first control mode.

A sheet conveying apparatus comprising:

• a conveying roller configured to convey a sheet;
• a motor configured to drive the conveying roller;
• a phase determiner configured to determine a rotation phase of a rotor of the motor;
• a speed determiner configured to determine a rotation speed of the rotor;
• and
• a controller having a first control mode in which a value of a torque current component and a value of an excitation current component are controlled so that a difference between an instruction phase indicating a target phase of the rotor and the rotation phase determined by the phase determiner is decreased to control the motor and a second control mode in which constant current is supplied to a winding of the motor to control the motor,
• wherein the torque current component is a current component having a current value represented in a rotating coordinate system based on the rotation phase, which generates torque in the rotor, and the excitation current component is a current component having a current value represented in the rotating coordinate system based on the rotation phase, which affects a strength of a magnetic flux through the winding of the motor, and
• wherein the controller switches a control mode to control the motor from the second control mode to the first control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value lower than a first threshold value to a value higher than or equal to the first threshold value in a state in which the motor is controlled in the second control mode, keeps the first control mode even if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the first threshold value to a value that is higher than or equal to a second threshold value lower than the first threshold value and that is lower than the first threshold value in a state in which the motor is controlled in the first control mode, and switches the control mode to control the motor from the first control mode to the second control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the second threshold value to a value lower than the second threshold value in the state in which the motor is controlled in the first control mode.

A document feeding apparatus comprising:

• a document tray in which an original document is loaded;
• a conveying roller configured to convey the original document loaded in the document tray;
• a motor configured to drive the conveying roller;
• a phase determiner configured to determine a rotation phase of a rotor of the motor;
• a speed determiner configured to determine a rotation speed of the rotor;
• and
• a controller having a first control mode in which a value of a torque current component and a value of an excitation current component are controlled so that a difference between an instruction phase indicating a target phase of the rotor and the rotation phase determined by the phase determiner is decreased to control the motor and a second control mode in which constant current is supplied to a winding of the motor to control the motor,
• wherein the torque current component is a current component having a current value represented in a rotating coordinate system based on the rotation phase, which generates torque in the rotor, and the excitation current component is a current component having a current value represented in the rotating coordinate system based on the rotation phase, which affects a strength of a magnetic flux through the winding of the motor, and
• wherein the controller switches a control mode to control the motor from the second control mode to the first control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value lower than a first threshold value to a value higher than or equal to the first threshold value in a state in which the motor is controlled in the second control mode, keeps the first control mode even if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the first threshold value to a value that is higher than or equal to a second threshold value lower than the first threshold value and that is lower than the first threshold value in a state in which the motor is controlled in the first control mode, and switches the control mode to control the motor from the first control mode to the second control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the second threshold value to a value lower than the second threshold value in the state in which the motor is controlled in the first control mode.

A document reading apparatus comprising:

• a document tray in which an original document is loaded;
• a conveying roller configured to convey the original document loaded in the document tray;
• a reading unit configured to read the original document conveyed by the conveying roller;
• a motor configured to drive the conveying roller;
• a phase determiner configured to determine a rotation phase of a rotor of the motor;
• a speed determiner configured to determine a rotation speed of the rotor;
• and
• a controller having a first control mode in which a value of a torque current component and a value of an excitation current component are controlled so that a difference between an instruction phase indicating a target phase of the rotor and the rotation phase determined by the phase determiner is decreased to control the motor and a second control mode in which constant current is supplied to a winding of the motor to control the motor,
• wherein the torque current component is a current component having a current value represented in a rotating coordinate system based on the rotation phase, which generates torque in the rotor, and the excitation current component is a current component having a current value represented in the rotating coordinate system based on the rotation phase, which affects a strength of a magnetic flux through the winding of the motor, and
• wherein the controller switches a control mode to control the motor from the second control mode to the first control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value lower than a first threshold value to a value higher than or equal to the first threshold value in a state in which the motor is controlled in the second control mode, keeps the first control mode even if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the first threshold value to a value that is higher than or equal to a second threshold value lower than the first threshold value and that is lower than the first threshold value in a state in which the motor is controlled in the first control mode, and switches the control mode to control the motor from the first control mode to the second control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the second threshold value to a value lower than the second threshold value in the state in which the motor is controlled in the first control mode.

An image forming apparatus comprising:

• a conveying roller configured to convey a recording medium;
• an image forming unit configured to form an image on the recording medium conveyed by the conveying roller;
• a motor configured to drive the conveying roller;
• a phase determiner configured to determine a rotation phase of a rotor of the motor;
• a speed determiner configured to determine a rotation speed of the rotor;
• and
• a controller having a first control mode in which a value of a torque current component and a value of an excitation current component are controlled so that a difference between an instruction phase indicating a target phase of the rotor and the rotation phase determined by the phase determiner is decreased to control the motor and a second control mode in which constant current is supplied to a winding of the motor to control the motor,
• wherein the torque current component is a current component having a current value represented in a rotating coordinate system based on the rotation phase, which generates torque in the rotor, and the excitation current component is a current component having a current value represented in the rotating coordinate system based on the rotation phase, which affects a strength of a magnetic flux through the winding of the motor, and
• wherein the controller switches a control mode to control the motor from the second control mode to the first control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value lower than a first threshold value to a value higher than or equal to the first threshold value in a state in which the motor is controlled in the second control mode, keeps the first control mode even if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the first threshold value to a value that is higher than or equal to a second threshold value lower than the first threshold value and that is lower than the first threshold value in a state in which the motor is controlled in the first control mode, and switches the control mode to control the motor from the first control mode to the second control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the second threshold value to a value lower than the second threshold value in the state in which the motor is controlled in the first control mode.

An image forming apparatus that form an image on a recording medium, the image forming apparatus comprising:

• a motor configured to drive a load;
• a phase determiner configured to determine a rotation phase of a rotor of the motor;
• a speed determiner configured to determine a rotation speed of the rotor;
• and
• a controller having a first control mode in which a value of a torque current component and a value of an excitation current component are controlled so that a difference between an instruction phase indicating a target phase of the rotor and the rotation phase determined by the phase determiner is decreased to control the motor and a second control mode in which constant current is supplied to a winding of the motor to control the motor,
• wherein the torque current component is a current component having a current value represented in a rotating coordinate system based on the rotation phase, which generates torque in the rotor, and the excitation current component is a current component having a current value represented in the rotating coordinate system based on the rotation phase, which affects a strength of a magnetic flux through the winding of the motor, and
• wherein the controller switches a control mode to control the motor from the second control mode to the first control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value lower than a first threshold value to a value higher than or equal to the first threshold value in a state in which the motor is controlled in the second control mode, keeps the first control mode even if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the first threshold value to a value that is higher than or equal to a second threshold value lower than the first threshold value and that is lower than the first threshold value in a state in which the motor is controlled in the first control mode, and switches the control mode to control the motor from the first control mode to the second control mode if the rotation speed of the rotor of the motor determined by the speed determiner is varied from a value higher than or equal to the second threshold value to a value lower than the second threshold value in the state in which the motor is controlled in the first control mode.