JP2017208930A - Motor control apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which: by using a low pass filter, a phase of a current value of the drive current used for position estimation is delayed compared with a phase of a current value of an actual drive current, causing an error in an actual rotor position and an estimated position.SOLUTION: A phase difference between a phase of a current value of a drive current to which a low pass filter is not applied and a phase of an induced voltage to which the low pass filter is applied is determined. On the basis of the phase difference, a correction value for correcting an estimated position is determined. Using the correction value, the estimated position is corrected, and drive control of a motor is performed on the basis of the corrected estimated position.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an apparatus for controlling driving of a motor.

  Conventionally, as a method of controlling the driving of the motor, the rotational position or rotational speed of the rotor of the motor is fed back, and the motor is driven based on the current value of the rotating coordinate system based on the rotational position of the rotor of the motor. A control method called vector control is known.

  When vector control is used, the drive current supplied to the winding of the motor is divided into a current component (q-axis current) that generates torque for rotating the rotor, and a current component (d-axis) that affects the magnetic flux strength of the rotor. Current) and control. As a result, even if the load torque applied to the rotor changes, the torque necessary for the rotation can be efficiently generated by controlling the q-axis current according to the change of the load torque. In other words, the load torque applied to the rotor, which has been regarded as a problem in the past, exceeds the output torque corresponding to the drive current supplied to the motor windings, and the rotor does not synchronize with the input signal. ) Can be prevented. Further, an increase in power consumption and an increase in motor sound due to excess torque can be suppressed.

  The vector control requires a configuration for estimating the rotor position. In Patent Literature 1, the current value of the drive current supplied to the winding of each phase of the motor is detected, and the induced voltage generated in the winding of each phase of the motor is calculated based on the detection result. A method is described in which the arc tangent of the ratio of the induced voltages is calculated to estimate the rotor position, and the motor drive is controlled based on the position estimation result.

Japanese Patent No. 5537565

  When calculating the induced voltage based on the detected current value, a low-pass filter may be used to remove high-frequency component noise contained in the current value. That is, a high-frequency component noise included in the current value is removed using a low-pass filter, and a current value from which the high-frequency component noise is removed is used for the calculation of the induced voltage.

  However, when the low-pass filter is used, the phase of the current value after the removal of the high-frequency component noise is delayed compared to the phase of the current value before the removal of the high-frequency component noise. That is, the phase of the current value used when calculating the induced voltage is delayed compared to the phase of the current value of the drive current actually supplied to the winding of each phase of the motor. As a result, the phase of the calculated induced voltage is delayed compared to the phase of the induced voltage actually generated in the winding of each phase of the motor. If the rotor position is estimated based on an induced voltage that is delayed in phase from the induced voltage that is actually generated in the winding of each phase of the motor, there will be an error between the actual rotor position and the estimated position. Will occur. If the motor drive control is performed based on the estimated position, the motor drive control may become unstable. For this reason, there has been a demand for a good configuration for reducing an error occurring between the actual rotor position and the estimated position.

  An object of the present invention is to suppress motor drive control from becoming unstable by performing motor drive control based on an estimated position where an error has occurred with respect to the actual rotor position.

In order to solve the above problems, the present invention provides:
In the motor control device that controls the drive of the motor,
Motor control means for performing feedback of the rotational position or rotational speed of the rotor of the motor and controlling the driving of the motor based on a current value of a rotational coordinate system based on the rotational position of the rotor of the motor;
Current detection means for detecting the current value of the drive current supplied to the winding of each phase of the motor and outputting a signal corresponding to the detected current value;
A filter circuit that reduces a component of a predetermined frequency band from a signal output from the current detection unit;
Phase difference determining means for determining a phase difference between a phase of the signal before the filter circuit is applied and a phase of the signal after the filter circuit is applied;
Position estimating means for estimating the rotational position of the rotor of the motor based on the signal after the filter circuit is applied;
Position correction value determining means for determining a position correction value for correcting the rotational position estimated by the position estimating means based on the phase difference determined by the phase difference determining means;
Position correcting means for correcting the rotational position estimated by the position estimating means based on the position correction value determined by the position correction value determining means;
Have
The motor control means controls driving of the motor based on the rotational position corrected by the position correction means.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the drive control of a motor becomes unstable by performing drive control of a motor based on the estimated position where the error produced with respect to the position of an actual rotor.

1 is a cross-sectional view illustrating an image forming apparatus according to a first embodiment. 2 is a block diagram illustrating a control configuration of the image forming apparatus. FIG. It is a block diagram which shows the structure of the motor control apparatus which concerns on 1st Embodiment. It is a figure which shows the relationship between the two-phase motor which consists of A phase and B phase, and d-axis and q-axis of a rotation coordinate system. It is a flowchart which shows the control method of the motor drive using the motor control apparatus which concerns on 1st Embodiment. It is a block diagram which shows the structure of the motor control apparatus which concerns on 2nd Embodiment. It is a flowchart which shows the control method of the motor drive using the motor control apparatus which concerns on 2nd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the shape of the component parts described in this embodiment and the relative arrangement thereof should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions, and the scope of the present invention is not limited. The present invention is not intended to be limited to the following embodiments. Note that the motor control device is not limited to the image forming apparatus.

[First Embodiment]
FIG. 1 is a cross-sectional view showing a configuration of a monochrome electrophotographic copying machine (hereinafter referred to as an image forming apparatus) 100 which is an image forming apparatus used in the present embodiment. The image forming apparatus is not limited to a monochrome electrophotographic copying machine, and may be, for example, an inkjet printer, a facsimile machine, a printing machine, a color image forming apparatus, or the like.

  The configuration and function of the image forming apparatus 100 will be described below with reference to FIG. The image forming apparatus 100 includes an automatic document feeder 201, a document reading device 202, and an image forming apparatus main body 301.

  Documents placed on the document placement unit 203 of the automatic document feeder 201 are fed one by one by a feed roller 204 and conveyed along a conveyance guide 206 onto a document glass table 214 of the document reading device 202. The Further, the document is transported at a constant speed by the transport belt 208 and discharged by a paper discharge roller 205 to a paper discharge tray (not shown) provided outside the automatic document feeder 201. During this time, the reflected light from the document image illuminated by the illumination 209 at the reading position of the document reading device 202 is guided to the image reading unit 101 by the optical system including the reflection mirrors 210, 211, 212, and the image reading unit 101 performs the image reading. Converted to a signal. The image reading unit 101 includes a lens, a CCD that is a photoelectric conversion element, a drive circuit for the CCD, and the like. The image signal output from the image reading unit 101 is subjected to various correction processes by an image processing unit 112 configured by a hardware device such as an ASIC, and then output to the image forming apparatus main body 301. As described above, the document is read.

  Further, there are a flow reading mode and a fixed reading mode as a document reading mode in the reading device 202. The flow reading mode is a mode in which an image of a document is read while the document is conveyed at a constant speed while the illumination system 209 and the optical system are fixed at predetermined positions. The fixed reading mode is a mode in which an original is placed on the original glass 214 of the reading apparatus 202 and an image of the original placed on the original glass 214 is read while moving the illumination system 209 and the optical system at a constant speed. is there. Normally, a sheet-like document is read in a flow reading mode, and a bound document such as a book or booklet is read in a fixed reading mode.

  Inside the image forming apparatus main body 301, sheet storage trays 302 and 304 are provided. Each of the sheet storage trays 302 and 304 can store different types of recording media. For example, A4 plain paper is stored in the sheet storage tray 302, and A4 thick paper is stored in the sheet storage tray 304. The recording medium is an image on which an image is formed by an image forming apparatus, and includes, for example, paper, a resin sheet, cloth, an OHP sheet, a label, and the like.

  The recording medium stored in the sheet storage tray 302 is fed by the paper feed roller 303 and sent out to the registration roller 308 by the transport roller 306. Also, the recording medium stored in the sheet storage tray 304 is fed by the paper feed roller 305 and sent out to the registration roller 308 by the transport rollers 307 and 306.

  The image signal output from the reading device 202 is input to an optical scanning device 311 including a semiconductor laser and a polygon mirror. Further, the outer peripheral surface of the photosensitive drum 309 is charged by the charger 310. After the outer peripheral surface of the photosensitive drum 309 is charged, a laser beam corresponding to an image signal input from the reading device 202 to the optical scanning device 311 passes through the polygon mirror and the mirrors 312 and 313 from the optical scanning device 311 and is photosensitive. The drum 309 is irradiated on the outer peripheral surface. As a result, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 309. As a method for charging the photosensitive drum, for example, a charging method using a corona charger or a charging roller is used.

  Subsequently, the electrostatic latent image is developed with toner in the developing device 314, and a toner image is formed on the outer peripheral surface of the photosensitive drum 309. The toner image formed on the photosensitive drum 309 is transferred to a recording medium by a transfer separator 315 provided at a position (transfer position) facing the photosensitive drum 309. At this time, the registration roller 308 sends the recording medium to the transfer position in synchronization with the toner image.

  As described above, the recording medium to which the toner image has been transferred is sent to the fixing device 318 by the conveyance belt 317, and is heated and pressurized by the fixing device 318 to fix the toner image to the recording medium. In this manner, the image forming apparatus 100 forms an image on the recording medium.

  When image formation is performed in the single-sided printing mode, the recording medium that has passed through the fixing device 318 is discharged to a discharge tray (not shown) by discharge rollers 319 and 324. When image formation is performed in the double-sided printing mode, after the fixing process is performed on the first surface of the recording medium by the fixing device 318, the recording medium is a discharge roller 319, a conveyance roller 320, and a reverse roller 321. Is conveyed to the reverse path 325. Thereafter, the recording medium is conveyed again to the registration roller 308 by the conveying rollers 322 and 323, and an image is formed on the second surface of the recording medium by the method described above. Thereafter, the recording medium is discharged to a discharge tray (not shown) by discharge rollers 319 and 324.

  In addition, when the recording medium on which the image is formed on the first surface is reversed so that the first surface faces downward and is discharged to the outside of the image forming apparatus 100, the recording medium that has passed through the fixing device 318 is discharged. The paper is conveyed in the direction toward the conveyance roller 320 through the paper roller 319. Thereafter, the rotation of the conveyance roller 320 is reversed immediately before the trailing edge of the recording medium passes through the nip portion of the conveyance roller 320. As a result, with the first surface of the recording medium facing downward, the recording medium can be transported in the direction toward the paper discharge roller 324 and discharged outside the image forming apparatus 100.

  The above is the description of the configuration and functions of the image forming apparatus 100.

  FIG. 2 is a block diagram illustrating an example of a control configuration of the image forming apparatus 100. As shown in FIG. 2, the system controller 151 includes a CPU (higher level device) 151a, a ROM 151b, and a RAM 151c. The system controller 151 includes an image processing unit 102, an operation unit 152, an analog / digital (A / D) converter 153, a high voltage control unit 155, a motor control device 157 (motor control device and motor control means), and DC load control. The unit 158, the sensors 159, and the AC driver 160 are connected. The system controller 151 can send and receive data and commands to and from each connected unit.

  The CPU 151a executes various sequences related to a predetermined image forming sequence by reading and executing various programs stored in the ROM 151b.

  The RAM 151c is a storage device. The RAM 151c stores various data such as a set value for the high-voltage control unit 155, a command value for the motor control device 157, and information received from the operation unit 152, for example.

  The system controller 151 transmits setting value data of various apparatuses provided in the image forming apparatus 100 necessary for image processing in the image processing unit 102 to the image processing unit 102. Furthermore, the system controller 151 receives signals from various devices (signals from the sensors 159), and sets a setting value for the high-voltage control unit 155 based on the received signals. The high voltage controller 155 supplies a necessary voltage to the high voltage unit 156 (the charger 310, the developer 314, the transfer separator 315, etc.) according to the set value set by the system controller 151.

  The A / D converter 153 receives the detection signal detected by the thermistor 154 for detecting the temperature of the fixing heater 161, converts the detection signal from an analog signal to a digital signal, and transmits it to the system controller 151. The system controller 151 controls the AC driver 160 based on the digital signal received from the A / D converter 153. The AC driver 160 controls the fixing heater 161 so that the temperature of the fixing heater 161 becomes a temperature necessary for performing the fixing process. The fixing heater 161 is a heater used for fixing processing and is included in the fixing device 318.

  The system controller 151 displays the operation screen for the user to set the type of recording medium to be used (hereinafter referred to as paper type) on the display unit provided in the operation unit 152. To control. The system controller 151 receives information set by the user, such as the type of paper to be used, from the operation unit 152, and controls the operation sequence of the image forming apparatus 100 based on the information set by the user. In addition, the system controller 151 transmits information indicating the state of the image forming apparatus to the operation unit 152. Note that the information indicating the state of the image forming apparatus is, for example, information such as the number of images formed, whether or not an image is being formed, occurrence of a jam, and a location where the jam occurs. The operation unit 152 displays information received from the system controller 151 on the display unit.

  As described above, the system controller 151 controls the operation sequence of the image forming apparatus 100.

  Next, the motor control device in the present embodiment will be described. The motor control device in the present embodiment controls driving of the motor using vector control. Vector control is a control method for controlling the driving of a motor based on a current value in a rotating coordinate system based on the rotational position of the rotor of the motor and performing feedback of the rotational position or rotational speed of the motor rotor. .

  In the following description, a stepping motor is used as a motor for driving a load, but the present invention is not limited to this. The load is an object driven by a motor. For example, various rollers (conveyance rollers) such as paper feed rollers 204, 303, and 305, registration rollers 308 and paper discharge rollers 319, photosensitive drums 309, conveyance belts 208 and 317, illumination systems 209, optical systems, and the like correspond to loads. To do. The motor control device of this embodiment can be applied to a motor that drives these loads. Further, the motor is not necessarily a two-phase motor. Furthermore, the motor in this embodiment is not provided with a sensor such as a rotary encoder for detecting the rotational position of the rotor of the motor.

  FIG. 3 is a block diagram illustrating an example of a configuration of a motor control device 157 that controls driving of a stepping motor (hereinafter referred to as a motor) 509.

  Hereinafter, a method in which the motor control device 157 according to this embodiment performs drive control of the motor 509 will be described with reference to FIGS. 3 and 4.

  FIG. 4 is a diagram showing a relationship between a motor 509 having two phases of A phase (first phase) and B phase (second phase) and the d-axis and q-axis of the rotating coordinate system. In FIG. 4, in the stationary coordinate system, the axis corresponding to the A-phase winding is defined as the α axis, and the axis corresponding to the B-phase winding is defined as the β-axis. In addition, an angle formed by the α axis in the stationary coordinate system and the direction of the magnetic flux (d-axis direction) created by the magnetic poles of the permanent magnet used in the rotor 402 is defined as θ. The rotational position of the rotor 402 is represented by an angle θ. In the vector control, the motor 509 is expressed by a d-axis along the magnetic flux direction of the rotor 402 and a q-axis along a direction advanced 90 degrees counterclockwise from the d-axis (perpendicular to the d-axis). A rotational coordinate system based on the rotational position θ of the rotor 402 is used.

  As shown in FIG. 3, the motor controller 157 in this embodiment includes a position controller 502, a current controller 503 (voltage generation means), coordinate converters 505 and 511, a PWM inverter (current supply means) 506, and the like. Is provided.

  The coordinate converter 511 represents a current vector corresponding to the drive current flowing in the A-phase and B-phase windings of the motor 509 from the stationary coordinate system represented by the α-axis and the β-axis by the q-axis and the d-axis. Convert coordinates to the rotating coordinate system. As a result, the drive current supplied to the A-phase and B-phase windings of the motor 509 is converted into a q-axis component (first current component) current value and a d-axis component (second current component) in the rotational coordinate system. It can be expressed using the current value. The q-axis component current corresponds to a torque current that causes the rotor 402 of the motor 509 to generate torque. The d-axis component current corresponds to an excitation current that affects the magnetic flux intensity of the rotor 402 of the motor 509 and does not contribute to the generation of torque of the rotor 402. The motor control device 157 can independently control the q-axis component current and the d-axis component current. That is, the torque necessary for the rotor 402 to rotate can be efficiently generated.

  The motor control device 157 estimates the rotational position θ of the rotor 402 of the motor 509 by a method described later, and performs vector control based on the estimation result. The CPU 151 a generates a command value (command position) θ_ref for the rotational position of the rotor 402 of the motor 509 and outputs the command value θ_ref to the motor control device 157 at a predetermined time period.

  The position controller (position control means) 502 generates the q-axis current command value iq_ref and the d-axis current command value id_ref so that the deviation between the rotational position θ of the rotor 402 of the motor 509 and the command value θ_ref becomes small. Output. Specifically, the position controller 502 generates the q-axis current command value iq_ref and the d-axis current command value id_ref so that the deviation between the rotational position θ of the rotor 402 of the motor 509 and the command value θ_ref becomes zero. And output. Further, the position controller 502 in the present embodiment is composed of a proportional (P), integral (I) compensator, but is composed of a proportional (P), integral (I), and differential (D) compensator. May be. When a permanent magnet is used for the rotor 402, the d-axis current command value id_ref that normally affects the magnetic flux intensity of the rotor 402 is set to 0, but the present invention is not limited to this.

  Current detectors (current detection means) 507 and 508 detect drive currents that flow through the A-phase and B-phase (each phase) windings of the motor 509, and signals corresponding to the detected current values are A / D converters. Output to 510.

  The signals output from the current detectors 507 and 508 are converted from analog values to digital values by the A / D converter 510, and the rotational position θ of the rotor 402 is set as the current values iα and iβ in the stationary coordinate system. And is represented by the following equation.

iα = I * cos θ (1)
iβ = I * sin θ (2)
These current values iα and iβ are input to a coordinate converter (coordinate conversion means) 511 and a low-pass filter (filter circuit) 518. The current value iα is also input to a phase difference determiner (phase difference determining means) 514.

  The low-pass filter 518 reduces high-frequency component noise (components in a predetermined frequency band) included in the current values iα and iβ, and calculates an induced voltage for the current values iα ′ and iβ ′ after the noise is reduced. Is output to a device 512 (induced voltage calculation means). In this embodiment, a low-pass filter is used, but the present invention is not limited to this. For example, a filter such as a band pass filter may be provided. The filter may be provided inside the induced voltage calculator.

  In the coordinate converter 511, the current values iα and iβ are coordinate-converted into the q-axis current value iq and the d-axis current value id in the rotating coordinate system by the following equations.

id = cos θ * iα + sin θ * iβ (3)
iq = −sin θ * iα + cos θ * iβ (4)
As described above, the coordinate converter 511 converts the current vector corresponding to the drive current flowing in the A-phase and B-phase windings of the motor 509 from the static coordinate system represented by the α axis and the β axis to the q axis and Coordinates are converted into a rotating coordinate system represented by the d axis.

  Subsequently, the deviation between the current value iq obtained by coordinate transformation by the coordinate transformer 511 and iq_ref output from the position controller 502 and the deviation between the current value id and id_ref output from the position controller 502 are as follows. Each is output to the current controller 503. The current controller 503 generates current values iq * and id * so that the deviations are reduced. Specifically, the current controller 503 generates the current values iq * and id * so that the deviations are zero. Thereafter, the current controller 503 generates drive voltages Vq and Vd corresponding to the current values iq * and id *, and outputs them to the coordinate converter 505. The current controller 503 in the present embodiment is composed of a proportional (P) and integral (I) compensator as in the case of the position controller 502. However, the proportional (P), integral (I), and differential (D) ) It may be composed of a compensator.

  The coordinate converter 505 reversely converts the drive voltages Vq and Vd in the rotating coordinate system output from the current controller 503 into the drive voltages Vα and Vβ in the stationary coordinate system according to the following equation.

Vα = cos θ * Vd−sin θ * Vq (5)
Vβ = sin θ * Vd + cos θ * Vq (6)
The coordinate converter 505 reversely converts the drive voltages Vq and Vd in the rotating coordinate system into the drive voltages Vα and Vβ in the stationary coordinate system, and then outputs Vα and Vβ to the PWM inverter 506 and the low-pass filter 518.

  Vα and Vβ output to the low pass filter 518 are output from the low pass filter 518 to the induced voltage calculator 512 as Vα ′ and Vβ ′ after the low pass filter 518 is applied.

  The PWM inverter 506 has a full bridge circuit. The full bridge circuit is driven by driving voltages Vα and Vβ input from the coordinate converter 505. As a result, the PWM inverter 506 generates drive currents iα and iβ corresponding to the drive voltages Vα and Vβ, and drives the motor 509 by supplying the drive currents iα and iβ to the windings of each phase of the motor 509. . In this embodiment, the PWM inverter has a full bridge circuit, but may be a half bridge circuit or the like.

Next, a method for estimating the rotational position θ of the rotor 402 will be described. For the estimation of the rotational position θ of the rotor 402, induced voltages induced in the A-phase and B-phase windings of the motor 509 by the rotation of the rotor 402 are used. The value of the induced voltage is calculated by the induced voltage calculator 512. Specifically, the induced voltages Eα ′ and Eβ ′ are calculated from the current values iα ′ and iβ ′ and the drive voltages Vα ′ and Vβ ′ input from the low-pass filter 518 to the induced voltage calculator 512 according to the following equations. .
Eα ′ = Vα′−R * iα′−L * diα ′ / dt (7)
Eβ ′ = Vβ′−R * iβ′−L * diβ ′ / dt (8)
Here, R is winding resistance, and L is winding inductance. The values of R and L are values specific to the motor 509 being used, and are stored in advance in a memory (not shown) or the like provided in the ROM 151b or the motor control device 157.

The induced voltages Eα ′ and Eβ ′ calculated by the induced voltage calculator 512 are input to the position estimator (position estimation means) 513. The induced voltage Eα ′ is also input to the phase difference determiner 514 and the period detector (period detection means) 515. The position estimator 513 estimates the rotational position θ ′ of the rotor 402 of the motor 509 from the ratio of the A-phase induced voltage Eα ′ and the B-phase induced voltage Eβ ′ by the following equation.
θ ′ = tan ^ −1 (−Eβ ′ / Eα ′) (9)

  The rotational position θ ′ of the rotor 402 obtained as described above is input to the position corrector 517. Further, in the present embodiment, the magnitude of the induced voltage induced in the winding of each phase of the motor is calculated, and the rotational position of the rotor is estimated by calculating the ratio of the magnitudes of the induced voltages. This is not the case. For example, the rotational position of the rotor may be estimated by calculating the ratio of the current values of the drive currents supplied to the windings of each phase of the motor.

  As described above, in the present embodiment, the current value of the current flowing through the winding of each phase of the motor is detected, and the noise of the high frequency component included in the detected current value is reduced using the low-pass filter. . The drive voltage is also input to the low pass filter. Then, the rotor is calculated by calculating the induced voltage induced in the winding of each phase of the motor based on the drive current and drive voltage to which the low-pass filter is applied, and calculating the ratio of the calculated induced voltage magnitudes. Is estimated. In the present embodiment, the induced voltage is calculated after applying the low-pass filter to the drive current and the drive voltage, but this is not restrictive. For example, after the induced voltage is calculated using the drive current and drive voltage before the low-pass filter is applied, the low-pass filter is applied to the calculated induced voltage, and the high-frequency component noise included in the induced voltage is reduced. The structure which reduces may be sufficient.

  However, when the low-pass filter is used, the phase of the signal after the low-pass filter is applied is delayed compared to the phase of the signal before the low-pass filter is applied. That is, in the present embodiment, the phases of the drive voltages Vα ′ and Vβ ′ and the drive currents iα ′ and iβ ′ after the low-pass filter are applied are the drive voltages Vα and Vβ and the drive current iα before the low-pass filter is applied. And the phase of iβ is delayed. As a result, the phase of the calculated induced voltages Eα ′ and Eβ ′ is delayed compared to the phase of the induced voltage actually generated in each phase winding of the motor. If the rotor position is estimated based on an induced voltage that is delayed in phase from the induced voltage that is actually generated in the winding of each phase of the motor, there will be an error between the actual rotor position and the estimated position. Will occur. As a result, the motor drive control may become unstable. Therefore, there is a demand for a good configuration for reducing an error that occurs between the actual rotor position and the estimated position. Note that the amount of phase delay caused by using a low-pass filter is not always a constant value. In addition, the drive current, the induced voltage, and the drive voltage in this embodiment periodically change with time in a sinusoidal shape.

  Hereinafter, a method for correcting an error occurring between the actual rotor position and the estimated position will be described with reference to FIG. In the motor control device 157 of the present embodiment, a phase difference determiner 514, a period detector 515, a position correction value determiner (position correction) (position correction) are used as circuits for correcting an error occurring between the actual rotor position and the estimated position. A value determining means) 516, a position corrector (position correcting means) 517, and the like.

  As described above, the phase difference determiner 514 receives the current value iα output from the A / D converter 510 and the induced voltage Eα ′ output from the induced voltage calculator 512. The phase difference determiner 514 determines the time difference (position) between the timing when the current value iα changes from a positive value to a negative value and the timing when the value of the induced voltage Eα ′ changes from a positive value to a negative value. Phase difference) cnt_diff is determined and output. In this embodiment, when the time difference cnt_diff is determined, the current value iα output from the A / D converter 510 and the induced voltage Eα ′ output from the induced voltage calculator 512 are used. is not. For example, any current value, induced voltage, or drive voltage before the low-pass filter is applied and any current value, induced voltage, or drive voltage after the low-pass filter is applied may be used. For example, the current value iα output from the A / D converter 510 and the current value iα ′ output from the low-pass filter 518 may be used. Further, the induced voltage Eα is calculated without applying the low-pass filter to the current value iα output from the A / D converter 510, and the low-pass filter is applied to the calculated induced voltage Eα. A configuration using the induced voltage Eα before applying the low-pass filter and the induced voltage Eα ′ after applying the low-pass filter may be used. Furthermore, in the present embodiment, the time difference cnt_diff is determined using the current value, the induced voltage, or the drive voltage in the A-phase winding, but this is not restrictive. For example, the current value or induced voltage or drive voltage in the B-phase winding may be used, or the time difference cnt_diff may be determined using both the A-phase winding and the B-phase winding. In the present embodiment, the time difference cnt_diff at which the current value iα and the induced voltage Eα ′ change from a positive value to a negative value is determined. For example, the time difference of the timing when the current value iα and the induced voltage Eα ′ change from a negative value to a positive value, the time difference of the maximum timing, or the time difference of the minimum timing Any configuration may be used.

  The period detector 515 detects the period cnt_cycle of the induced voltage Eα ′ output from the induced voltage calculator 512 and outputs it to the position correction value determiner 516. In the present embodiment, the period of the induced voltage Eα ′ is detected. However, the period of the induced voltage, the drive current, and the drive voltage is the same regardless of before and after the low-pass filter is applied. What is necessary is just to detect and output as a period cnt_cycle. The period detection method includes, for example, detecting the time from the timing when the induced voltage Eα ′ changes from a negative value to a positive value until the timing when the induced voltage Eα ′ changes again from a negative value to a positive value. There is a way to do it. Further, since the cycle cnt_cycle is a value determined from the number of rotations of the motor, a method of calculating using the rotation speed of the rotor or the rotation command speed may be used.

The position correction value determiner 516 determines a position correction value θ_err for the rotational position of the rotor based on a value obtained by dividing the time difference cnt_diff output from the phase difference determiner 514 by the period cnt_cycle output from the period detector 515. . Specifically, it determines using the following formula | equation (10).
θ_err = 2π * cnt_diff / cnt_cycle (10)

In the present embodiment, the position correction value θ_err is calculated using Expression (10), but the present invention is not limited to this. For example, a table indicating the relationship between the time difference cnt_diff, the cycle cnt_cycle, and the position correction value θ_err may be stored in advance in the ROM 151b and the position correction value θ_err may be determined using the table.

  The position correction value determiner 516 outputs the position correction value θ_err obtained as described above to the position corrector 517.

The position corrector 517 corrects the rotational position θ ′ estimated by the position estimator 513 using the position correction value θ_err, and outputs the corrected rotational position θ of the rotor. Specifically, the rotational position θ ′ is corrected using the following equation (11).
θ = θ ′ + θ_err (11)

Thereafter, the above-described control is repeatedly performed based on the corrected rotational position θ. That is, the motor control device 157 performs drive control of the motor using vector control. By controlling the driving of the motor using the vector control, it is possible to suppress the motor from going out of step, an increase in motor noise due to excess torque, and an increase in power consumption. In the vector control in this embodiment, a rotational coordinate system based on the rotational position θ of the rotor 402 is used, but the present invention is not limited to this. That is, a rotational coordinate system based on the rotational position command value θ_ref may be used. In the vector control according to the present embodiment, the rotation position θ of the rotor 402 is fed back to control the driving of the motor 509. However, the present invention is not limited to this. For example, a configuration in which the rotation speed ω of the rotor 402 is fed back to control the driving of the motor 509 may be employed. Specifically, for example, the rotational speed ω of the rotor 402 is calculated using the following equation based on the time change of the rotational position θ of the rotor 402.
ω = dθ / dt (12)

Further, the CPU 151 a outputs the rotation command speed ω_ref of the rotor 402 to the motor control device 600. Based on the deviation between the rotation speed ω of the rotor 402 and the rotation command speed ω_ref, the drive current to be supplied to the winding of each phase of the motor is determined. A configuration for controlling the driving of the motor 509 as described above may be used.

  As described above, the motor control device 157 in this embodiment determines the phase delay caused by the application of the low-pass filter, corrects the estimated position based on the determination result, and sets the corrected estimated position. Based on this, drive control of the motor is performed. As a result, the error between the actual rotational position and the estimated rotational position, which is caused by using the low-pass filter, can be reduced as much as possible. Further, by reducing the error between the actual rotational position and the estimated rotational position as much as possible, it is possible to prevent the motor drive control from becoming unstable.

  FIG. 5 is a flowchart showing a motor drive control method using the motor control device 157. Hereinafter, drive control of the motor 509 in the present embodiment will be described with reference to FIG. The processing of this flowchart is executed by the motor control device 157 that has received an instruction from the CPU 151a.

  First, when the CPU 151 a outputs an enable signal “H” to the motor control device 157, the motor control device 157 starts driving control of the motor 509. The enable signal is a signal for determining the operation / stop of the motor 509. When the enable signal is “L (low level)”, the motor drive is stopped and the enable signal is “H (high level)”. In this case, the motor drive is set to the operating state. When the motor control device 157 starts vector control, in S1001, the position estimator 513 estimates the rotational position θ ′ based on the induced voltages Eα ′ and Eβ ′ output from the induced voltage calculator 512, and the motor control device. In step S157, the process proceeds to step S1002.

  In S1002, the phase difference determiner 514 determines the time difference cnt_diff between the timing at which the current value iα changes from a positive value to a negative value and the timing at which the value of the induced voltage Eα ′ changes from a positive value to a negative value. The process proceeds to S1003. In step S <b> 1003, the period detector 515 detects the period cnt_cycle of the induced voltage Eα ′ output from the induced voltage calculator 512.

  Next, in S1004, the position correction value determiner 516 uses the time difference cnt_diff output from the phase difference determiner 514, the period cnt_cycle output from the period detector 515, and Equation (10) to determine the rotational position of the rotor. A position correction value θ_err is determined. Thereafter, in S1005, the position corrector 517 corrects the rotational position θ ′ estimated by the position estimator 513 using the position correction value θ_err and the equation (11). The motor control device performs motor drive control based on the rotational position θ corrected by the position corrector 517.

  Next, when the motor control device continues the vector control in S1006, the process returns to S1001 again. In step S1006, when the motor control device ends vector control, the motor control device 157 proceeds with the process, and the motor control device ends vector control.

  As described above, the motor control device 157 in this embodiment determines the phase delay caused by the application of the low-pass filter, corrects the estimated position based on the determination result, and sets the corrected estimated position. Based on this, drive control of the motor is performed. Specifically, the phase difference determiner 514 determines that the current value iα output from the A / D converter 510 and the induced voltage Eα ′ output from the induced voltage calculator 512 are negative values. The time difference cnt_diff from the timing of changing to is determined. Further, the period cnt_cycle of the induced voltage Eα ′ output from the induced voltage calculator 512 is detected. Further, the position correction value θ_err of the rotational position of the rotor is determined using the time difference cnt_diff and the period cnt_cycle, and the rotational position θ ′ estimated by the position estimator 513 is corrected using the position correction value θ_err. The motor control device 157 performs drive control of the motor based on the corrected estimated position θ. As a result, the error between the actual rotational position and the estimated rotational position, which is caused by using the low-pass filter, can be reduced as much as possible. Further, by reducing the error between the actual rotational position and the estimated rotational position as much as possible, it is possible to prevent the motor drive control from becoming unstable.

  Note that the method of correcting the estimated position based on the phase delay caused by the application of the low-pass filter in the present embodiment is not limited to the case of estimating the position using the induced voltage, but other estimation methods. It can also be applied. Further, the method for correcting the estimated position based on the phase delay caused by the application of the low-pass filter in the present embodiment is not limited to the low-pass filter, and is also applied to other filters such as a band-pass filter. be able to.

[Second Embodiment]
The configuration of the image forming apparatus is the same as that of the first embodiment.

  In the first embodiment, as a method of correcting an error between the actual rotational position and the estimated rotational position, which is caused by using a filter, the rotational position is estimated using the position correction value θ_err after estimating the rotational position θ ′. A method of correcting the above has been described.

  In this embodiment, before performing position estimation, the phase of a signal (induced voltage, drive current, drive voltage, etc.) used for position estimation is corrected, and position estimation is performed based on the corrected signal.

  FIG. 6 is a block diagram illustrating an example of the configuration of the motor control device 158 according to the present embodiment. As shown in FIG. 6, the motor control device 158 according to the present embodiment is provided with a phase corrector (phase correction means) 520 and the like.

  Hereinafter, a control method for controlling driving of the motor 509 using the motor control device 158 according to the present embodiment will be described with reference to FIG. In addition, description is abbreviate | omitted about the part similar to the control method in 1st Embodiment.

  The phase difference determiner 514 determines and outputs the time difference cnt_diff in the same manner as in the first embodiment. In this embodiment, when the time difference cnt_diff is determined, the current value iα output from the A / D converter 510 and the induced voltage Eα ′ output from the induced voltage calculator 512 are used. is not. For example, the current value, induced voltage, or drive voltage before the low-pass filter is applied and the current value, induced voltage, or drive voltage after the low-pass filter is applied may be used. Further, the current value iα output from the A / D converter 510 and the current value iα ′ output from the low-pass filter 518 may be used. Further, the induced voltage Eα is calculated without applying the low-pass filter to the current value iα output from the A / D converter 510, and the low-pass filter is applied to the calculated induced voltage Eα. A configuration using the induced voltage Eα before applying the low-pass filter and the induced voltage Eα ′ after applying the low-pass filter may be used. Furthermore, in the present embodiment, the time difference cnt_diff is determined using the current value, the induced voltage, or the drive voltage in the A-phase winding, but this is not restrictive. For example, the current value or induced voltage or drive voltage in the B-phase winding may be used, or the time difference cnt_diff may be determined using both the A-phase winding and the B-phase winding. In the present embodiment, the time difference cnt_diff at which the current value iα and the induced voltage Eα ′ change from a positive value to a negative value is determined. For example, the time difference of the timing when the current value iα and the induced voltage Eα ′ change from a negative value to a positive value, the time difference of the maximum timing, or the time difference of the minimum timing is determined. It may be configured to do so.

  The time difference cnt_diff determined by the phase difference determiner 514 is output to the phase corrector 520. In addition, the induced voltages Eα ′ and Eβ ′ output from the induced voltage calculator 512 are input to the phase corrector 520.

  The phase corrector 520 corrects the phases of the induced voltages Eα ′ and Eβ ′ based on the time difference cnt_diff. That is, the phase corrector 520 corrects the phase delay generated by the low-pass filter 518 using the time difference cnt_diff, and outputs the induced voltages Eα and Eβ whose phases are corrected to the position estimator 513. The position estimator 513 estimates the rotational position θ using Expression (9). In the present embodiment, the phase of the induced voltages Eα ′ and Eβ ′ is corrected using the time difference cnt_diff, but the present invention is not limited to this. That is, using the time difference cnt_diff, the phases of the drive voltages Vα ′ and Vβ ′ and the drive currents iα ′ and iβ ′ used when calculating the induced voltage are corrected, and the drive voltage and drive current whose phases are corrected are used. To calculate the induced voltage. Thereafter, the rotational position θ may be estimated using the calculated induced voltage.

  Thereafter, the motor control device 158 controls the driving of the motor 509 by the method described in the first embodiment. In other words, the motor control device 158 performs drive control of the motor using vector control. By controlling the driving of the motor using the vector control, it is possible to suppress the motor from going out of step, an increase in motor noise due to excess torque, and an increase in power consumption.

  As described above, the motor control device 158 in this embodiment determines the phase delay caused by the application of the low-pass filter, corrects the phase of the induced voltage based on the determination result, and corrects the phase. The rotor position is estimated using the induced voltage. Thereafter, drive control of the motor is performed based on the estimated position. As a result, the error between the actual rotational position and the estimated rotational position, which is caused by using the low-pass filter, can be reduced as much as possible. Further, by reducing the error between the actual rotational position and the estimated rotational position as much as possible, it is possible to suppress the drive control of the motor from becoming unstable or uncontrollable. .

  FIG. 7 is a flowchart showing a motor drive control method using the motor control device 158 in the present embodiment. Hereinafter, drive control of the motor 509 in the present embodiment will be described with reference to FIG. The processing of this flowchart is executed by the motor control device 158 that has received an instruction from the CPU 151a.

  First, when the CPU 151 a outputs an enable signal “H” to the motor control device 158, the motor control device 158 starts driving control of the motor 509. When the motor control device 158 starts vector control, in S1001, the induced voltage calculator 512 causes the induced voltage Eα ′ based on the drive voltages Vα ′ and Vβ ′ and the drive currents iα ′ and iβ ′ output from the low-pass filter 518. And Eβ ′. Thereafter, the motor control device 158 advances the process to S1002.

  In S1002, the phase difference determiner 514 determines the time difference cnt_diff between the timing at which the current value iα changes from a positive value to a negative value and the timing at which the value of the induced voltage Eα ′ changes from a positive value to a negative value. The process proceeds to S1003.

  In step S1003, the phase corrector 520 corrects the phases of the induced voltages Eα ′ and Eβ ′ output from the induced voltage calculator 512 using the time difference cnt_diff output from the phase difference determiner 514, and corrects the induced induction. The voltages Eα and Eβ are output. Thereafter, in S1004, the position estimator 513 estimates the rotational position θ based on the induced voltages Eα and Eβ output from the phase corrector 520 using Expression (9), and the process proceeds to S1005.

  Next, in S1005, when the motor control device continues vector control, the process returns to S1001 again. In step S1005, when the motor control device ends vector control, the motor control device 158 proceeds with the process, and the motor control device ends vector control.

  As described above, in this embodiment, before performing position estimation, the phase of a signal (induced voltage, driving current, driving voltage, etc.) used for position estimation is corrected, and the position is determined based on the signal whose phase is corrected. Estimate. Specifically, the induced voltages Eα ′ and Eβ ′ are calculated using the drive voltages Vα ′ and Vβ ′ to which the low-pass filter is applied and the drive currents iα ′ and iβ ′. Further, the phase difference between the current value iα to which the low-pass filter is not applied and the induced voltage Eα ′ calculated by the induced voltage calculator is determined. Based on the phase difference, the phases of the induced voltages Eα ′ and Eβ ′ are corrected, and the rotational position θ is estimated using the induced voltages Eα and Eβ whose phases are corrected. Thereafter, drive control of the motor is performed based on the estimated position θ. As a result, the error between the actual rotational position and the estimated rotational position, which is caused by using the low-pass filter, can be reduced as much as possible. Further, by reducing the error between the actual rotational position and the estimated rotational position as much as possible, it is possible to suppress the drive control of the motor from becoming unstable or uncontrollable. .

  As described above, the method of correcting the phase of a signal used for position estimation (induced voltage, drive current, drive voltage, etc.) and performing position estimation based on the phase-corrected signal uses an induced voltage. Thus, the present invention is not limited to the case of estimating the position, and can be applied to other estimation methods. For example, a high-frequency component current is superimposed on the drive current supplied to the winding of each phase of the motor, and only the high-frequency component current is extracted by a band-pass filter or the like, and the position is determined based on the extracted high-frequency component current. The present invention can also be applied to a method such as estimation.

151a CPU
402 Rotor 157 Motor controller 507, 508 Current detector 509 Stepping motor 518 Low-pass filter 513 Position estimator 514 Phase difference determiner 516 Position correction value determiner 517 Position corrector

Claims (15)

In the motor control device that controls the drive of the motor,
Motor control means for performing feedback of the rotational position or rotational speed of the rotor of the motor and controlling the driving of the motor based on a current value of a rotational coordinate system based on the rotational position of the rotor of the motor;
Current detection means for detecting the current value of the drive current supplied to the winding of each phase of the motor and outputting a signal corresponding to the detected current value;
A filter circuit that reduces a component of a predetermined frequency band from a signal output from the current detection unit;
Phase difference determining means for determining a phase difference between a phase of the signal before the filter circuit is applied and a phase of the signal after the filter circuit is applied;
Position estimating means for estimating the rotational position of the rotor of the motor based on the signal after the filter circuit is applied;
Position correction value determining means for determining a position correction value for correcting the rotational position estimated by the position estimating means based on the phase difference determined by the phase difference determining means;
Position correcting means for correcting the rotational position estimated by the position estimating means based on the position correction value determined by the position correction value determining means;
Have
The motor control device controls the drive of the motor based on the rotational position corrected by the position correction device. In the motor control device that controls the drive of the motor,
Motor control means for performing feedback of the rotational position or rotational speed of the rotor of the motor and controlling the driving of the motor based on a current value of a rotational coordinate system based on the rotational position of the rotor of the motor;
Current detection means for detecting the current value of the drive current supplied to the winding of each phase of the motor and outputting a signal corresponding to the detected current value;
A filter circuit that reduces a component of a predetermined frequency band from a signal output from the current detection unit;
Phase difference determining means for determining a phase difference between a phase of the signal before the filter circuit is applied and a phase of the signal after the filter circuit is applied;
Phase correction means for correcting the phase of the signal after the filter circuit is applied based on the phase difference determined by the phase difference determination means;
Position estimating means for estimating the rotational position of the rotor of the motor based on the signal corrected by the phase correcting means;
Have
The motor control device, wherein the motor control means controls driving of the motor based on the rotational position estimated by the position estimation means.   The motor control device according to claim 1, wherein the filter circuit reduces high-frequency component noise from a signal output from the current detection unit. The motor control device
Current supply means for generating a drive current for supplying a drive current for driving the motor to each of the first phase winding and the second phase winding of the motor;
Voltage generating means for generating a driving voltage for driving the current supply means;
From the drive voltage generated by the voltage generation means and the signal corresponding to the current value of the drive current after the filter circuit is applied, the first-phase winding and the second are rotated by the rotation of the rotor of the motor. Induced voltage calculation means for calculating the induced voltage generated in the phase winding;
Have
4. The phase difference determining means determines a phase difference between a phase of a signal before the filter circuit is applied and a phase of an induced voltage calculated by the induced voltage calculating means. The motor control device according to any one of the above.   The magnitude of the induced voltage generated in the first phase winding and the second phase winding of the motor, and the drive current supplied to each of the first phase winding and the second phase winding of the motor 5. The motor control device according to claim 4, wherein the current value and the drive voltage generated by the voltage generation unit periodically change in a sinusoidal manner over time.   The phase difference determining unit is configured such that the induced voltage value calculated by the induced voltage calculating unit changes from a positive value to a negative value, and the signal output from the current detecting unit changes from a positive value to a negative value. The time difference from the timing at which the induced voltage is calculated, or the timing at which the value of the induced voltage calculated by the induced voltage calculating means changes from a negative value to a positive value and the signal output from the current detecting means is from a negative value. A time difference between the timing of changing to a positive value, or the time difference between the timing at which the value of the induced voltage calculated by the induced voltage calculation means becomes maximum and the timing at which the signal output from the current detection means becomes maximum, Or the timing at which the value of the induced voltage calculated by the induced voltage calculation means becomes minimum and the timing at which the signal output from the current detection means becomes minimum The difference, the motor control device according to claim 4 or 5, characterized in that determining either. The motor control device may calculate either the periodically changing induced voltage cycle calculated by the induced voltage calculating unit or the periodically changing signal cycle output from the current detecting unit. Having period detecting means for detecting,
2. The position correction value determining means determines the position correction value based on a value obtained by dividing a time difference determined by the phase difference determining means by a period detected by the period detecting means. The motor control device according to claim 5 or 6. The position estimating means estimates the rotational position of the rotor of the motor from the ratio of the magnitude of the induced voltage of the first phase and the magnitude of the induced voltage of the second phase calculated by the induced voltage calculating means;
The position correction means corrects the rotational position of the rotor of the motor estimated by the position estimation means based on the position correction value determined by the position correction value determination means;
The said motor control means controls the drive of the said motor based on the rotation position correct | amended by the said position correction means, The motor according to any one of claims 4 to 7, wherein the motor is driven. Motor control device. The motor control device
Position control means for generating and outputting the current value of the drive current in the rotating coordinate system so that the deviation between the command position output from the host device and the rotational position corrected by the position correcting means is reduced;
Coordinate conversion means for coordinate-converting the current value of the stationary coordinate system detected by the current detection means into the current value of the rotation coordinate system based on the rotational position corrected by the position correction means;
Have
The motor control means is configured to reduce the deviation between the current value output from the position control means and the current value coordinate-converted by the coordinate conversion means, so that the first-phase winding and the second-phase 9. The motor control apparatus according to claim 8, wherein driving of the motor is controlled by controlling a current value of a driving current supplied to the winding. The phase correction unit corrects the phase of the induced voltage of the first phase and the second phase calculated by the induced voltage calculation unit based on the phase difference determined by the phase difference determination unit,
The position estimating means estimates the rotational position of the rotor of the motor from the ratio of the magnitude of the induced voltage of the first phase and the magnitude of the induced voltage of the second phase whose phase is corrected by the phase correcting means;
The said motor control means controls the drive of the said motor based on the rotational position estimated by the said position estimation means, The motor according to any one of claims 4 to 6 which quotes claim 2 characterized by the above-mentioned. Motor control device. The motor control device
Position control means for generating and outputting the current value of the drive current in the rotating coordinate system so that the deviation between the command position output from the host device and the rotational position estimated by the position estimating means is reduced;
Coordinate conversion means for coordinate-converting the current value of the stationary coordinate system detected by the current detection means into the current value of the rotation coordinate system based on the rotational position estimated by the position estimation means;
Have
The motor control means is configured to reduce the deviation between the current value output from the position control means and the current value coordinate-converted by the coordinate conversion means, so that the first-phase winding and the second-phase The motor control device according to claim 10, wherein driving of the motor is controlled by controlling a current value of a driving current supplied to the winding. The drive current is represented in the rotating coordinate system using a first current component that generates torque in the rotor of the motor and a second current component that affects the magnetic flux intensity of the rotor of the motor. ,
The motor control means controls the driving of the motor by controlling the value of the second current component to be 0 and controlling the value of the first current component. Item 12. The motor control device according to any one of Items 1 to 11. A current supply means for generating a drive current for supplying a drive current for driving the motor to each of a first phase winding and a second phase winding of the motor in a motor control device for controlling the drive of the motor;
Voltage generating means for generating a driving voltage for driving the current supply means;
Current detection means for detecting the current value of the drive current supplied to each of the first phase winding and the second phase winding of the motor by the current supply means and outputting a signal corresponding to the detected current value; ,
A filter circuit for reducing high-frequency component noise from the signal output from the current detection means;
From the drive voltage generated by the voltage generation means and the signal corresponding to the current value of the drive current after the filter circuit is applied, the first-phase winding and the second are rotated by the rotation of the rotor of the motor. Induced voltage calculation means for calculating the induced voltage generated in the phase winding;
Position estimating means for estimating the rotational position of the rotor of the motor from the ratio between the magnitude of the induced voltage of the first phase calculated by the induced voltage calculating means and the magnitude of the induced voltage of the second phase;
The timing at which the value of the induced voltage of the first phase winding calculated by the induced voltage calculating means changes from a positive value to a negative value and the signal output from the current detecting means changes from a positive value to a negative value. Phase difference determining means for determining a time difference from the timing of changing to a value;
A period detecting means for detecting a period of the induced voltage of the winding of the first phase which is calculated by the induced voltage calculating means and periodically changes in time in a sine wave;
Position correction value determination for determining a position correction value for correcting the rotational position estimated by the position estimation means based on a value obtained by dividing the time difference determined by the phase difference determination means by the period detected by the period detection means. Means,
Position correcting means for correcting the rotational position of the rotor of the motor estimated by the position estimating means based on the position correction value determined by the position correction value determining means;
Position control means for generating and outputting the current value of the drive current in the rotating coordinate system so that the deviation between the command position output from the host device and the rotational position corrected by the position correcting means is reduced;
Coordinate conversion means for coordinate-converting the current value of the stationary coordinate system detected by the current detection means into the current value of the rotation coordinate system based on the rotational position corrected by the position correction means;
Driving to be supplied to the first phase winding and the second phase winding of the motor so that the deviation between the current value output from the position control means and the current value coordinate-converted by the coordinate conversion means is small. A motor control device that controls driving of the motor by controlling a current value of a current. An image forming apparatus for forming an image on a recording medium,
A motor driving the load;
The motor control device according to any one of claims 1 to 13,
Have
The image forming apparatus, wherein the motor control device controls driving of a motor that drives the load. The image forming apparatus according to claim 14, wherein the load is a conveyance roller that conveys the recording medium.

Images