JP2018174671A - Motor control device, sheet transfer device, and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a step of a current waveform caused by a change of a timing for detecting drive current flowing through winding of a motor according to a duty ratio of a PWM signal.SOLUTION: After current corresponding to a PWM signal whose duty ratio is 50% is detected in a high period, current corresponding to the PWM signal whose duty ratio is 50%, based on a triangular wave carrier with phase inverted, is also detected in a low period. A correction value is determined based on a current value detected in a state in which the duty ratio is 50%, and the current value detected during motor driving is corrected based on the determined correction value.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a motor control device that controls a motor, a sheet conveying device, and an image forming apparatus.

  2. Description of the Related Art Conventionally, in motor drive control, a control method for detecting a current value of a drive current flowing in a motor winding and controlling a drive current supplied to the winding based on the detected current value is known.

  FIG. 15 is a diagram illustrating an example of the configuration of a motor drive circuit 50 that drives a motor. As shown in FIG. 15, the motor drive circuit 50 includes FETs Q1 to Q4 as switching elements, a motor winding L1, and the like. Specifically, the FETs Q1 to Q4 constitute an H bridge circuit, and the winding L1 is connected so as to connect a connection point between the FETs Q1 and Q3 and a connection point between the FETs Q2 and Q4. The drain terminals of the FETs Q1 and Q2 are connected to a 24V power supply terminal, and the source terminals of the FETs Q3 and Q4 are connected to one end of the resistor 200. Furthermore, the other end of the resistor 200 is connected to the ground (GND). That is, the resistor 200 is grounded. The motor has a first phase winding and a second phase winding, and a motor drive circuit is provided corresponding to each of the first phase and the second phase of the motor. Further, it is assumed that the motor drive circuit is driven independently for each phase. The motor is controlled based on the current value detected in the first phase and the current value detected in the second phase.

  The FETs Q1 and Q4 are driven by PWM + which is a PWM signal, and the FETs Q2 and Q3 are driven by PWM− which is a PWM signal. Note that PWM + and PWM− are in an opposite phase relationship. That is, when PWM + is “H (high level)”, PWM− is “L (low level)”. Further, when PWM− is “H”, PWM + is “L”. When the PWM signal is ‘H’, the operation of the FET is turned on. When the PWM signal is ‘L’, the operation of the FET is turned off.

  FIG. 16 is a time chart showing the relationship between PWM +, PWM−, and the current value I of the drive current flowing through the winding L1.

  In FIG. 16, a period T1 is a period in which the drive current I flowing through the winding L1 is positive, that is, the drive current I flows in the direction of the arrow shown in FIG. The period T2 is a period in which the drive current I flowing through the winding L1 is negative, that is, the drive current I flows in the direction opposite to the arrow shown in FIG.

  In the period T1, when PWM + is “H (high level)”, the drive current flows in the order of the power supply, the FET Q1, the winding L1, the FET Q4, and the GND. Thereafter, when PWM + becomes ‘L (low level)’, an induced electromotive force is generated in the winding L <b> 1 in a direction to prevent a change in current. As a result, a drive current flows in the order of GND, FET Q3, winding L1, FET Q2, and power supply. In the period T2, when PWM + is ‘L’, the drive current flows in the order of the power source, the FET Q2, the winding L1, the FET Q3, and the GND. Thereafter, when PWM + becomes ‘H’, an induced electromotive force is generated in the winding L <b> 1 in a direction to prevent a change in current. As a result, a drive current flows in the order of GND, FET Q4, winding L1, FET Q1, and power supply.

  The current value I is detected based on the voltage Vsns applied to the resistor 200. However, as described above, in the period T1, when PWM + is “H”, the drive current flows in the order of the power source 1, the FET Q1, the winding L1, the FET Q4, and the GND. In the period T1, when PWM + is “L”, the drive current flows in the order of GND, FET Q3, winding L1, FET Q2, and power source 1. That is, in the period T1, there are a case where the drive current flows in a direction from the power supply side to the GND and a case where the drive current flows in a direction from the GND toward the power supply side. The same applies to the period T2. Accordingly, when a resistor is provided at the position shown in FIG. 15 and the driving current I is detected based on the voltage Vsns across the resistor, the direction of the actual current flowing through the resistor and the direction of the detected driving current are determined. It does not match.

  In Patent Document 1, a resistor is provided between the motor drive circuit and the ground. In addition, a configuration is described in which switching means for switching the polarity of the voltage Vsns across the resistor is provided, and the switching means switches the polarity of Vsns in accordance with the PWM signal.

  In the configuration described in Patent Document 1, the switching element can respond to switching between PWM + 'H' and 'L' because the time interval for switching between PWM + 'H' and 'L' is short. There may be no case. In this case, the polarity of Vsns is switched although it is not necessary to switch the polarity of Vsns, and the direction of the actual current flowing in the resistor may not match the direction of the detected drive current.

  Therefore, the present applicant has proposed a configuration in which the current value in the longer period is detected between the period (high period) in which PWM + is ‘H’ and the period (low period) in which ‘L’ is ‘L’. Specifically, as shown in FIG. 17, the present applicant detects the current value of the high period when the duty ratio (ratio of the high period to one PWM + cycle) is 50% or more, and the duty ratio is 50 In the case of less than%, a configuration for detecting the current value in the low period is proposed.

  By using such a configuration, it is possible to prevent the direction of the actual current flowing through the resistor from being inconsistent with the direction of the detected drive current.

JP-A-8-99645

  When a configuration in which the current value in the longer period of the high period and the low period is detected is used, a difference occurs in the detection result due to the transient response characteristics of the drive current flowing in the winding. Specifically, the current value detected during the high period is different from the current value detected during the low period. Therefore, when the current value is detected in the longer period of the high period and the low period, the duty ratio changes from a value less than 50% to a value greater than 50%, or the duty ratio is a value greater than 50%. When the current value is changed to a value less than 50%, the detected current waveform is distorted. Specifically, as shown in FIG. 18, a step occurs in the detected current waveform. If the current waveform is distorted, the drive current supplied to the winding cannot be properly controlled. As a result, the control of the motor becomes unstable.

  In view of the above problems, an object of the present invention is to reduce a step generated in a current waveform due to a change in timing for detecting a drive current flowing in a motor winding according to a duty ratio of a PWM signal.

In order to solve the above problems, a motor control device according to the present invention includes:
A first mode for detecting the current value of the drive current flowing in the motor winding, correcting the detected current value, and controlling the drive current based on the corrected current value, and a correction value for correcting the current value. A motor control device comprising: a second mode to be determined;
A drive circuit comprising a plurality of switching elements constituting an H-bridge circuit, to which the windings are connected;
A PWM signal for controlling on and off operations of the plurality of switching elements, a first level signal that is one of a high level and a low level, and a second level signal that is the other of a high level and a low level; Is generated based on a first triangular wave as a carrier wave, and a second PWM signal composed of the first level signal and the second level signal is generated as the first PWM signal. Pulse generating means for generating based on a second triangular wave having a phase opposite to the phase of the triangular wave of
In the first mode, the current value of the drive current supplied to the winding by the drive circuit in response to the first PWM signal is detected at a timing determined by the duty ratio of the first PWM signal, and detected. Correction means for correcting the current value;
Have
The correction means detects the current value of the drive current once for each period of the first triangular wave,
Further, the correction means, in the second mode, the current value of the drive current supplied by the drive circuit to the winding in response to the first PWM signal in a state where the duty ratio is a predetermined value, Detecting the first PWM signal in a first period of the first level;
Further, in the second mode, the correction means detects the current value of the drive current in the first period, and then the drive circuit causes the second PWM signal to be in a state where the duty ratio is the predetermined value. And detecting the current value of the drive current supplied to the winding in response to the second period in which the second PWM signal is at the second level,
Further, the correction means reduces a current value detected during a period in which the first PWM signal is at the high level in the first mode based on a current value detected in the second mode. Decide
Further, the correction means increases a current value detected during a period in which the first PWM signal is at the low level in the first mode based on the current value detected in the second mode. Decide
In the first mode, when the duty ratio is larger than the predetermined value, the correction unit detects a current value of the drive current during a period in which the first PWM signal is at the high level, and detects the detected current When the value is corrected based on the first correction value and the duty ratio is smaller than the predetermined value, the current value of the drive current is detected during a period in which the first PWM signal is at the low level, and detection is performed. The corrected current value based on the second correction value,
The pulse generation unit generates the PWM signal based on the current value corrected by the correction unit.

  According to the present invention, it is possible to reduce the step generated in the current waveform due to the change in the timing for detecting the drive current flowing in the motor winding according to the duty ratio of the PWM signal. As a result, it is possible to prevent the motor control from becoming unstable.

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 figure which shows the relationship between the two-phase motor which consists of A phase and B phase, and the rotating coordinate system represented by d axis | shaft and q axis | shaft. 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 structure of a motor drive part. It is a block diagram which shows the structure of the PWM generator 203 which concerns on 1st Embodiment. It is a figure explaining the structure by which a PWM signal is produced | generated. It is a figure explaining the method by which a PWM signal is produced | generated. It is a figure which shows the structure of a current value generator. It is a figure explaining the method of correct | amending an electric current value. It is a time chart explaining the method to determine the correction value based on 1st Embodiment. It is a flowchart which shows the control method of the motor which concerns on 1st Embodiment. It is a flowchart which shows the method to determine the correction value based on 1st Embodiment. It is a block diagram which shows the structure of the motor control apparatus which performs speed feedback control. It is a figure explaining the structure of a motor drive circuit. It is a time chart which shows the relationship between PWM +, PWM-, and the electric current value I of the drive current which flows into winding L1. It is a figure explaining the method of detecting an electric current value according to a duty ratio. It is a figure which shows the waveform of the detected electric current.

  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 limited. It is not intended to be limited to the following embodiments. In the following description, a case where the motor control device is provided in the image forming apparatus will be described, but the motor control device is not limited to the image forming apparatus. For example, it is also used for a sheet conveying apparatus that conveys a sheet such as a recording medium or a document.

[First Embodiment]
[Image forming apparatus]
FIG. 1 is a cross-sectional view illustrating a configuration of a monochrome electrophotographic copying machine (hereinafter referred to as an image forming apparatus) 100 having a sheet conveying device used in the present embodiment. The image forming apparatus is not limited to a copying machine, and may be, for example, a facsimile machine, a printing machine, a printer, or the like. The recording method is not limited to the electrophotographic method, and may be, for example, an ink jet. Further, the format of the image forming apparatus may be either monochrome or color.

  The configuration and function of the image forming apparatus 100 will be described below with reference to FIG. As illustrated in FIG. 1, the image forming apparatus 100 includes a document feeding device 201, a reading device 202, and an image printing device 301.

  The originals stacked on the original stacking unit 203 of the original feeder 201 are fed one by one by the paper feed roller 204 and conveyed along the conveyance guide 206 onto the original glass plate 214 of the reading apparatus 202. Further, the document is conveyed at a constant speed by the conveyance belt 208 and discharged to a discharge tray (not shown) by a discharge roller 205. Reflected light from the document image illuminated by the illumination 209 at the reading position of the reading device 202 is guided to the image reading unit 111 by the optical system including the reflection mirrors 210, 211, and 212, and converted into an image signal by the image reading unit 111. Is done. The image reading unit 111 includes a lens, a CCD that is a photoelectric conversion element, a CCD drive circuit, and the like. The image signal output from the image reading unit 111 is subjected to various correction processes by the image processing unit 112 configured by a hardware device such as an ASIC, and then output to the image printing apparatus 301. As described above, the document is read. That is, the document feeder 201 and the reading device 202 function as a document reading device.

  Further, there are a first reading mode and a second reading mode as document reading modes. The first reading mode is a mode in which an image of a document conveyed at a constant speed is read by an illumination system 209 and an optical system fixed at a predetermined position. The second reading mode is a mode in which an image of an original placed on the original glass 214 of the reading apparatus 202 is read by the illumination system 209 and the optical system that move at a constant speed. Normally, an image of a sheet-like document is read in the first reading mode, and an image of a bound document such as a book or booklet is read in the second reading mode.

  Inside the image printing apparatus 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 size plain paper is stored in the sheet storage tray 302, and A4 size 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. For example, paper, a resin sheet, a cloth, an OHP sheet, a label, and the like are included in the recording medium.

  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. 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 charger 315 provided at a position (transfer position) facing the photosensitive drum 309. In synchronization with the transfer timing, the registration roller 308 feeds the recording medium to the transfer position.

  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.

  When the recording medium on which the image is formed on the first surface is discharged face-down to the outside of the image forming apparatus 100, the recording medium that has passed through the fixing device 318 passes through the discharge roller 319 and the conveyance roller 320. It is transported in the direction toward. Thereafter, the rotation of the conveyance roller 320 is reversed immediately before the rear end of the recording medium passes through the nip portion of the conveyance roller 320, so that the recording medium is discharged to the discharge roller with the first surface of the recording medium facing downward. The image is discharged to the outside of the image forming apparatus 100 via the H.324.

  The above is the description of the configuration and functions of the image forming apparatus 100. In addition, the load in this invention is the target object driven by a motor. For example, various rollers (conveyance rollers) such as paper feed rollers 204, 303, 305, registration rollers 308 and paper discharge rollers 319, photosensitive drums 309, conveyance belts 208, 317, illumination system 209, optical system, etc. Corresponds to the load. The motor control device of this embodiment can be applied to a motor that drives these loads.

  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 151a, a ROM 151b, and a RAM 151c. The system controller 151 is connected to the image processing unit 112, the operation unit 152, an analog / digital (A / D) converter 153, a high voltage control unit 155, a motor control device 600, sensors 159, and an AC driver 160. . 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 600, 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 112 to the image processing unit 112. Further, the system controller 151 receives a signal from the sensors 159 and sets a setting value of the high voltage control unit 155 based on the received signal. The high voltage controller 155 supplies a necessary voltage to the high voltage unit 156 (charging device 310, developing device 314, transfer charging device 315, etc.) according to the set value set by the system controller 151. The sensors 159 include a sensor that detects a recording medium conveyed by the conveyance roller.

  The motor control device 600 controls a motor 509 that drives a load in accordance with a command output from the CPU 151a. In FIG. 2, only the motor 509 is described as the motor of the image forming apparatus. However, in reality, the image forming apparatus is provided with a plurality of motors. Further, a configuration in which one motor control device controls a plurality of motors may be employed. Further, in FIG. 2, only one motor control device is provided, but in actuality, it is assumed that a plurality of motor control devices are provided in the image forming apparatus.

  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 from the operation unit 152 and controls an 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. The information indicating the state of the image forming apparatus is, for example, information related to the number of images formed, the progress of the image forming operation, sheet material jamming or double feeding in the document reading apparatus 201 and the image printing apparatus 301, and the like. 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.

[Motor control unit]
Next, the motor control device in the present embodiment will be described. The motor control device in the present embodiment controls the motor using vector control.

<Vector control>
First, a method in which the motor control device 600 according to the present embodiment performs vector control will be described with reference to FIGS. 3 and 4. In the following description, the motor is not provided with a sensor such as a rotary encoder for detecting the rotational phase of the rotor of the motor, but may be provided with a sensor such as a rotary encoder.

  FIG. 3 shows a stepping motor (hereinafter referred to as a motor) 509 having two phases of A phase (first phase) and B phase (second phase), and a rotating coordinate system represented by d-axis and q-axis. It is a figure which shows the relationship. In FIG. 3, an α axis that is an axis corresponding to the A phase winding and a β axis that is an axis corresponding to the B phase winding are defined in the static coordinate system. In FIG. 3, the d-axis is defined along the direction of the magnetic flux created by the magnetic poles of the permanent magnet used in the rotor 402, and the direction is 90 degrees counterclockwise from the d-axis (perpendicular to the d-axis). The q-axis is defined along the direction of The angle formed by the α axis and the d axis is defined as θ, and the rotational phase of the rotor 402 is represented by the angle θ. In the vector control, a rotational coordinate system based on the rotational phase θ of the rotor 402 is used. Specifically, in the vector control, a current vector corresponding to a drive current flowing through the winding is a current component in the rotating coordinate system, and a q-axis component (torque current component) for generating torque in the rotor and the winding And a d-axis component (excitation current component) that affects the intensity of the magnetic flux penetrating the magnetic field.

  Vector control is a motor that performs phase feedback control that controls the value of the torque current component and the value of the excitation current component so that the deviation between the command phase representing the target phase of the rotor and the actual rotation phase is small. It is the control method which controls. In addition, the motor is controlled by performing speed feedback control that controls the value of the torque current component and the value of the excitation current component so that the deviation between the command speed representing the target speed of the rotor and the actual rotation speed becomes small. There is also a method.

  FIG. 4 is a block diagram showing an example of the configuration of a motor control device 600 that controls the motor 509. The motor control device 600 in this embodiment includes a motor control unit 157 that controls the motor using vector control and a motor drive unit 158 that drives the motor by supplying a drive current to the motor windings. The motor control device 157 is composed of at least one ASIC and executes each function described below.

  As shown in FIG. 4, the motor control unit 157 supplies a drive current to the phase controller 502, the current controller 503, the coordinate inverse converter 505, the coordinate converter 511, and the motor winding as a circuit for performing vector control. PWM inverter 506 and the like. The coordinate converter 511 represents the current vector corresponding to the drive current flowing through the A-phase and B-phase windings of the motor 509 from the stationary coordinate system represented by the α-axis and β-axis by the q-axis and the d-axis. Convert coordinates to a rotating coordinate system. As a result, the drive current flowing in the winding is represented by the current value of the q-axis component (q-axis current) and the current value of the d-axis component (d-axis current) that are current values in the rotating coordinate system. Note that the q-axis current corresponds to a torque current that causes the rotor 402 of the motor 509 to generate torque. Further, the d-axis current corresponds to an excitation current that affects the strength of magnetic flux passing through the winding of the motor 509 and does not contribute to the generation of torque of the rotor 402. The motor control unit 157 can independently control the q-axis current and the d-axis current. As a result, the motor control unit 157 can efficiently generate the torque necessary for the rotor 402 to rotate by controlling the q-axis current according to the load torque applied to the rotor 402.

  The motor control unit 157 determines the rotational phase θ of the rotor 402 of the motor 509 by a method described later, and performs vector control based on the determination result. The CPU 151a generates a command phase θ_ref representing the target phase of the rotor 402 of the motor 509, and outputs the command phase θ_ref to the motor control unit 157 at a predetermined time period.

  The subtractor 101 calculates a deviation between the rotational phase θ of the rotor 402 of the motor 509 and the command phase θ_ref and outputs the deviation to the phase controller 502.

  The phase controller 502 uses the q-axis current command value iq_ref and the d-axis so that the deviation output from the subtractor 101 becomes small based on proportional control (P), integral control (I), and differential control (D). A current command value id_ref is generated and output. Specifically, the phase controller 502 controls the q-axis current command value iq_ref and the d-axis current command value id_ref so that the deviation output from the subtractor 101 is 0 based on P control, I control, and D control. Is generated and output. The P control is a control method for controlling the value to be controlled based on a value proportional to the deviation between the command value and the estimated value. The I control is a control method for controlling the value to be controlled based on a value proportional to the time integral of the deviation between the command value and the estimated value. The D control is a control method for controlling the value to be controlled based on a value proportional to the time change of the deviation between the command value and the estimated value. The phase controller 502 in the present embodiment generates the q-axis current command value iq_ref and the d-axis current command value id_ref based on PID control, but is not limited to this. For example, the phase controller 502 may generate the q-axis current command value iq_ref and the d-axis current command value id_ref based on the PI control. When a permanent magnet is used for the rotor 402, the d-axis current command value id_ref that normally affects the strength of the magnetic flux passing through the winding is set to 0, but the present invention is not limited to this.

The drive current flowing in the A-phase and B-phase windings of the motor 509 is detected by the motor drive unit 158 by a method described later. The current value of the drive current detected by the motor drive unit 158 is expressed by the following equation using the current vector phase θe shown in FIG. 3 as the current values iα and iβ in the stationary coordinate system. The phase θe of the current vector is defined as an angle formed by the α axis and the current vector. I represents the magnitude of the current vector.
iα = I * cos θe (1)
iβ = I * sin θe (2)

These current values iα and iβ are input to the coordinate converter 511 and the induced voltage determiner 512.

The coordinate converter 511 converts the current values iα and iβ in the stationary coordinate system into the current value iq of the q-axis current and the current value id of the d-axis current 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)

  The subtractor 102 receives the q-axis current command value iq_ref output from the phase controller 502 and the current value iq output from the coordinate converter 511. The subtractor 102 calculates a deviation between the q-axis current command value iq_ref and the current value iq, and outputs the deviation to the current controller 503.

  Further, the subtracter 103 receives the d-axis current command value id_ref output from the phase controller 502 and the current value id output from the coordinate converter 511. The subtractor 103 calculates a deviation between the d-axis current command value id_ref and the current value id, and outputs the deviation to the current controller 503.

  The current controller 503 generates drive voltages Vq and Vd based on PID control so that the deviations are reduced. Specifically, the current controller 503 generates drive voltages Vq and Vd so that the deviations become 0, and outputs them to the coordinate inverse converter 505. That is, the current controller 503 functions as a generation unit. The current controller 503 in the present embodiment generates the drive voltages Vq and Vd based on PID control, but is not limited to this. For example, the current controller 503 may generate the drive voltages Vq and Vd based on PI control.

The coordinate inverse converter 505 inversely 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 inverse converter 505 outputs the inversely converted drive voltages Vα and Vβ to the induced voltage determiner 512, the PWM inverter 506, and the current value generator 530. The current value generator 530 will be described later.

  The PWM inverter 506 has a full bridge circuit. The full bridge circuit (motor drive circuit) has the same configuration as the motor drive circuit 50 described in FIG. In FIG. 15, the winding L <b> 1 is actually a winding provided in the motor 509. That is, the winding L1 is provided outside the motor control device 157. The full bridge circuit is driven by a PWM signal based on the drive voltages Vα and Vβ input from the coordinate inverse 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 the PWM inverter may be a half bridge circuit or the like.

Next, a configuration for determining the rotational phase θ will be described. For the determination of the rotational phase θ of the rotor 402, values of induced voltages Eα and Eβ 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 determined (calculated) by the induced voltage determiner 512. Specifically, the induced voltages Eα and Eβ are input from the A / D converter 510 to the induced voltage determiner 512 and the current values iα and iβ input from the coordinate inverse converter 505 to the induced voltage determiner 512. From the drive voltages Vα and Vβ, it is determined by the following equation.
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 the ROM 151b or a memory (not shown) provided in the motor control device 600.

  The induced voltages Eα and Eβ determined by the induced voltage determiner 512 are output to the phase determiner 513.

The phase determiner 513 determines the rotational phase θ of the rotor 402 of the motor 509 based on the ratio of the induced voltage Eα and the induced voltage Eβ output from the induced voltage determiner 512 according to the following equation.
θ = tan ^ −1 (−Eβ / Eα) (9)

  In the present embodiment, the phase determiner 513 determines the rotational phase θ by performing a calculation based on Expression (9), but this is not restrictive. For example, a table indicating the relationship between the induced voltage Eα and the induced voltage Eβ and the rotational phase θ corresponding to the induced voltage Eα and the induced voltage Eβ is stored in the ROM 151b or the like, and the rotational phase θ is determined by referring to the table. You may decide.

  The rotation phase θ of the rotor 402 obtained as described above is input to the subtractor 101, the coordinate inverse converter 505, and the coordinate converter 511.

  The motor control device 157 repeatedly performs the above control.

  As described above, the motor control device 157 according to the present embodiment performs vector control using phase feedback control that controls the current value in the rotating coordinate system so that the deviation between the command phase θ_ref and the rotating phase θ is small. By performing the vector control, it is possible to suppress the motor from being stepped out, an increase in motor noise due to excess torque, and an increase in power consumption.

[Motor drive unit]
As described above, in the drive control of the motor, the current value of the drive current flowing through the winding is detected, and the drive current flowing through the winding is controlled based on the detected current value. That is, in the drive control of the motor, a configuration for detecting the current value of the drive current flowing through the winding and a configuration for supplying the drive current to the winding are required.

  FIG. 5 is a diagram illustrating an example of the configuration of the motor driving unit 158 in the present embodiment. As shown in FIG. 5, the motor driving unit 158 includes a PWM inverter 506a in the A phase, an A / D converter 510a, and a current value generator 530a. The motor drive unit 158 includes a B-phase PWM inverter 506b, an A / D converter 510b, and a current value generator 530b. Note that the PWM inverter 506 shown in FIG. 4 includes a PWM inverter 506a and a PWM inverter 506b. The A / D converter 510 shown in FIG. 4 includes an A / D converter 510a and an A / D converter 510b. Furthermore, the current value generator 530 shown in FIG. 4 includes a current value generator 530a and a current value generator 530b. As described above, the PWM inverter, the A / D converter, and the current value generator are provided corresponding to the A phase and the B phase of the motor 509, and are driven independently for each phase. Since the configuration of the PWM inverter 506a and the configuration of the PWM inverter 506b are the same, FIG. 5 shows a specific configuration of the PWM inverter 506a. The PWM inverter 506a amplifies the voltage signal at both ends of the motor drive circuit 50a, the PWM generator 203 that generates a PWM signal for controlling the on / off operation of the plurality of FETs provided in the motor drive circuit 50a, and the resistor 200. An amplifier 300 is provided.

  Further, as shown in FIG. 5, the motor control unit 157 determines the value of the induced voltage generated in the B-phase winding and the induced voltage determiner 512a that determines the value of the induced voltage generated in the A-phase winding. And an induced voltage determiner 512b. The induced voltage determiner 512 shown in FIG. 4 includes an induced voltage determiner 512a and an induced voltage determiner 512b.

  Hereinafter, a method in which the motor driving unit 158 supplies a driving current to the A-phase winding and a method in which the motor driving unit 158 detects a current value of the driving current flowing in the A-phase winding will be described. In addition, about B phase, since it is the structure similar to A phase, description is abbreviate | omitted. Also, description of the same parts as those already described in FIGS. 15 to 18 will be omitted.

<Method of supplying drive current>
First, a method in which the motor driving unit 158 supplies a driving current to the winding will be described.

  FIG. 6 is a block diagram showing a configuration of the PWM generator 203 in the present embodiment. FIG. 7 is a diagram illustrating a configuration in which a PWM signal is generated. As shown in FIG. 6, the PWM generator 203 includes a carrier wave generation unit 522 that generates a triangular wave carrier wave having a predetermined frequency, a comparator 203a that compares the modulated wave and the carrier wave to generate a PWM signal, and a comparator 203a. A phase inverter 524 for inverting the phase of the PWM signal is provided. Further, the PWM generator 203 is a carrier wave inverting unit 523 for inverting the phase of the triangular wave carrier wave output from the carrier wave generating unit 522, a changeover switch 525 for switching the carrier wave output to the comparator 203a, and an inversion control for controlling the changeover switch 525. Part 521. In this embodiment, the frequency of the triangular wave carrier wave (predetermined frequency) is synchronized with the frequency at which the CPU 151a controls the motor control device 600, that is, the frequency at which the CPU 151a outputs the command phase θ_ref to the motor control device 600. It shall be.

  In the following description, it is assumed that the triangular wave carrier wave output from the carrier wave generation unit 522 is input to the comparator 203a.

  As shown in FIG. 7, the comparator 203a is a PWM signal by comparing the drive voltage Vα as a modulated wave output from the motor control unit 157 with the triangular wave as the carrier wave generated by the carrier wave generation unit 522. Generate and output PWM +.

  The phase inverter 524 inverts the phase of PWM + output from the comparator 203a and outputs PWM−, which is a PWM signal whose phase is inverted. In addition, when the period from the timing when the value of the triangular wave becomes the minimum value to the next timing when the value becomes the minimum value is one cycle, the waveform of one period of the triangular wave (the waveform from the minimum value to the next minimum value) is The waveform is symmetric with respect to the timing at which the value of the triangular wave reaches the maximum value. The triangular wave carrier wave in the A phase is synchronized with the triangular wave carrier wave in the B phase. The changeover switch 525, the inversion control unit 521, and the carrier wave inversion unit 523 will be described later.

  FIG. 8 is a diagram illustrating a method for generating a PWM signal. Hereinafter, a method of generating a PWM signal will be described with reference to FIG.

  As described above, the comparator 203a compares the drive voltage Vα as a modulated wave with the triangular wave carrier wave to generate a PWM signal. Specifically, the comparator 203a sets PWM + as “H” during a period (high period) when the driving voltage Vα is larger than the triangular wave carrier wave and to “L” during a period (low period) when the driving voltage Vα is smaller than the triangular wave carrier wave. Generate. The PWM generator 203 generates PWM− in which the phase of PWM + is inverted.

  As shown in FIG. 5, the PWM generator 203 outputs PWM + to the FETs Q1 and Q4, and outputs PWM− to the FETs Q2 and Q3. The FETs Q1 to Q4 are controlled to be turned on / off by PWM + and PWM−. As a result, the magnitude and direction of the drive current supplied to the A-phase winding L1 can be controlled.

  In this embodiment, when the drive voltage is 24V, the duty ratio is 100%, when the drive voltage is 0V, the duty ratio is 50%, and when the drive voltage is -24V, the duty ratio is 0%. To do. That is, in the present embodiment, the drive voltage Vα is a value corresponding to the duty ratio of PWM +. In this embodiment, the ratio of the high period to the PWM + period is defined as the duty ratio, but the ratio of the low period to the PWM + period may be defined as the duty ratio.

<Method for detecting drive current>
Next, a method for detecting the current value of the drive current flowing through the winding by the motor drive unit 158 will be described.

  As described above, the drive current flowing through the winding is detected based on the voltage Vsns applied to the resistor 200. The amplifier 300 amplifies the signal of the voltage Vsns and outputs it to the A / D converter 510a. The A / D converter 510a converts the voltage Vsns from an analog value to a digital value and outputs it to the current value generator 530a. In addition, the current value generator 530 a receives the drive voltage Vα output from the motor control unit 157 and the frequency and phase information as the triangular wave carrier information output from the PWM generator 203.

  FIG. 9 is a diagram illustrating a configuration of the current value generator 530a. The current value generator 530a includes a detection control unit 901, a detection value generation unit 902, a correction control unit 903, a correction value storage unit 904, and a correction value generation unit 905.

The detection control unit 901 controls the detection value generation unit 902 and the correction control unit 903 based on the drive voltage Vα output from the motor control unit 157.
Specifically, the detection control unit 901 controls the detection value generation unit 902 to sample the voltage value Vsns during the low period when the drive voltage Vα is negative (duty ratio is less than 50%).

  Based on a command from the detection control unit 901, the detection value generation unit 902 first generates a triangular wave carrier wave after the PWM + generated by the PWM generator 203 falls (switches from “H” to “L”). The voltage value Vsns is sampled at the timing when the value is reached. Then, the detection value generation unit 902 generates the current value Isns by inverting the polarity of the sampled voltage value Vsns. In addition, when the drive voltage is 0 V or higher (duty ratio is 50% or higher), the detection control unit 901 controls the detection value generation unit 902 to sample the voltage value Vsns during the high period. Based on a command from the detection control unit 901, the detection value generation unit 902 first sets the triangular carrier wave to the extreme value after the PWM + generated by the PWM generator 203 rises (switches from 'L' to 'H'). The voltage value Vsns is sampled at the timing as follows. Then, the detection value generation unit 902 generates the current value Isns without inverting the polarity of the sampled voltage value Vsns. The detection value generation unit 902 may perform a process of inverting the polarity of the current value Isns after generating the current value Isns based on the sampled voltage value Vsns.

  As described above, by sampling the voltage value Vsns at the timing when the triangular wave carrier wave reaches the extreme value, it is possible to prevent the digital value from being sampled at the timing when the PWM signal rises or falls. As a result, it is possible to prevent noise generated due to switching of the switching element when the PWM signal rises or falls from being included in the sampled value.

<Method of correcting the current value Isns>
Next, a method for correcting the detected current value Isns will be described. In the present embodiment, by applying the following configuration to the motor driving unit 158, a step generated in the detected current waveform is reduced.

  FIG. 10 is a diagram for explaining a method of correcting the current value. FIG. 10 shows linear reference functions ref1 (t) and ref2 (t) used as a reference for correcting the drive current I (t), the sampling timings ts1 and ts2, and the current value Isns. T represents time. The reference function ref1 (t) indicates a case where the drive current I increases linearly during the H period of the PMW signal (PWM +), and the reference function ref2 (t) indicates the drive current I during the L period of the PMW signal (PWM +). Shows a case where the linearity decreases linearly. In FIG. 10, a case where a PWM signal with a duty ratio DR = 50% is generated by the PWM generator 203 is shown as an example.

  As shown in FIG. 10, the value I (ts1) of the drive current at the sampling timing ts1 within the H period is higher by Δi1 than the reference value ref1 (ts1) indicated by the reference function. For this reason, the correction value C1 in the H period is determined as C1 = −Δi1 so that the detection value Isns of the drive current I is decreased by Δi1. In addition, the drive current value I (ts2) at the detection timing ts2 within the L period is lower by Δi2 than the reference value ref2 (ts2) indicated by the reference function. For this reason, the correction value C2 in the L period is determined as C2 = Δi2 so that the detection value Isns of the drive current I is increased by Δi2. The correction values C1 and C2 are stored in advance in the correction value storage unit 904 shown in FIG.

  The detection control unit 901 instructs the correction control unit 903 which of the correction value C1 for the H period and the correction value C2 for the L period should be used to correct the detection value Isns. Specifically, the detection control unit 901 controls the correction control unit 903 to correct the current value Isns based on the correction value C1 when the duty ratio is 50% or more. Further, when the duty ratio is less than 50%, the detection control unit 901 controls the correction control unit 903 so as to correct the current value Isns based on the correction value C2.

  The correction control unit 903 corrects the detection value Isns generated by the detection value generation unit 902 according to an instruction from the detection control unit 901. Specifically, the correction control unit 903 corrects the detection value Isns by adding the correction value C1 or C2 read from the correction value storage unit 904 to the detection value Isns, and outputs the corrected value as the current value Iα. To do.

<Method for determining correction value>
Next, a specific method for determining the correction values C1 and C2 will be described. As described above, in order to determine the correction values C1 and C2, it is necessary to determine Δi1 and Δi2.

  In the present embodiment, Δi1 and Δi2 are determined based on the current value detected in a state where the duty ratio is 50%, but the duty ratio may not be 50%.

  FIG. 11 is a time chart illustrating a method for determining Δi1 and Δi2. FIG. 11A is a diagram showing the relationship between the triangular wave carrier wave and the duty ratio. FIG. 11B is a diagram showing a PWM signal generated based on the triangular wave carrier wave and the duty ratio shown in FIG. FIG.11 (c) is a figure which shows the electric current supplied to the coil | winding based on the PWM signal shown in FIG.11 (b). FIG. 11D is a diagram illustrating timing for detecting (sampling) the current value. Note that the period Ts at which the detection value generation unit 902 performs sampling in this embodiment is synchronized with the period of the triangular wave carrier wave. That is, the detection value generation unit 902 in this embodiment performs sampling once for each period of the triangular wave carrier wave.

  Hereinafter, a specific method for determining the correction values C1 and C2 will be described with reference to FIG. In the following description, it is assumed that supply of current to the winding of the motor is started at time t0 in FIG.

  As shown in FIG. 11, the detection value generation unit 902 samples the voltage value Vsns (t1) at the timing (time t1) when the triangular wave carrier wave reaches the extreme value first after the PWM + rises, and the current value Isns ( t1) is generated and output to the correction value generation unit 905. After that, the detection value generation unit 902 samples the voltage value Vsns (t3) at the timing (time t3) when the triangular wave carrier wave reaches the extreme value first after PWM + rises again, and generates the current value Isns (t3). And output to the correction value generation unit 905. In this way, the current value in the high period can be detected by detecting the current value at the timing when the triangular wave carrier wave becomes the extreme value first after the PWM + rises. Note that Isns (t) indicates a current value generated based on the voltage value Vsns (t) sampled at time t.

  When a predetermined time T1 has elapsed from time t1, the inversion control unit 521 controls the changeover switch 525 so that the triangular wave carrier wave output from the carrier wave inversion unit 523 is input to the comparator 203a. As a result, a current based on the triangular wave carrier wave having a phase opposite to that of the triangular wave carrier wave generated by the carrier wave generating unit 522 is supplied to the winding.

  When a predetermined time T2 has elapsed after the inversion control unit 521 controls the changeover switch 525, the detection value generation unit 902 first has a timing (time t12) at which the triangular wave carrier wave reaches an extreme value after PWM + falls. The voltage value Vsns (t12) is sampled. Then, the detection value generation unit 902 generates a current value Isns (t12) based on the voltage value Vsns (t12) and outputs the current value Isns (t12) to the correction value generation unit 905. Thereafter, the detection value generation unit 902 samples the voltage value Vsns (t14) at the timing (time t14) when the triangular wave carrier wave reaches the extreme value first after PWM + falls again, and generates the current value Isns (t14). And output to the correction value generation unit 905. In this way, the current value in the low period can be detected by detecting the current value at the timing when the triangular wave carrier wave reaches the extreme value first after the PWM + falls. When the predetermined time T1 elapses from time t12, the detection value generation unit 902 ends sampling of the voltage value Vsns (t). Thus, the current value generator 530a detects the current value at a predetermined period based on the triangular wave carrier wave. Note that sampling is performed after a predetermined time T2 has elapsed since the triangular wave carrier wave whose phase has been inverted is input to the comparator 203a, because the current that fluctuates due to the inverted phase of the triangular wave carrier wave is stabilized. This is because sampling is performed in a state. That is, the predetermined time T2 is longer than the minimum necessary time for the current that fluctuates due to the phase of the triangular wave carrier to be inverted to stabilize.

  In the present embodiment, the predetermined time T1 is set so that the detection value generation unit 902 samples the voltage value Vsns (t) twice, but this is not restrictive. For example, the predetermined time T1 may be a time at which sampling is performed at least once, for example, the sampling is set to be performed three times.

  The correction value generation unit 905 calculates an average value iH of the input current value Isns (t1) and the current value Isns (t3). The correction value generation unit 905 calculates an average value iL of the input current value Isns (t12) and the current value Isns (t14).

The correction value generation unit 905 determines Δi1 and Δi2 using the following equation (10).
Δi1 = Δi2 = | iH−iL | / 2 (10)

Then, the correction value generation unit 905 determines the correction values C1 and C2 by the following equations (11) and (12).
C1 = −Δi1 (11)
C2 = Δi2 (12)

  The correction value generation unit 905 stores the determined correction values C1 and C2 in the correction value storage unit 905.

  In the present embodiment, the correction values C1 and C2 are determined as described above.

  FIG. 12 is a flowchart illustrating a motor control method performed by the motor control device 600. Below, control of the motor 509 in this embodiment is demonstrated using FIG. The processing of this flowchart is executed by the motor control device 600 that has received an instruction from the CPU 151a.

  First, in S1001, when the enable signal 'H' is output from the CPU 151a to the motor control device 600, the motor control device 600 operates based on a command output from the CPU 151a. The enable signal is a signal that permits or prohibits the operation of the motor control device 600. When the enable signal is “L (low level)”, the CPU 151 a prohibits the operation of the motor control device 600. That is, the motor control device 600 stops. When the enable signal is “H (high level)”, the CPU 151 a permits the operation of the motor control device 600. That is, the motor control device 600 operates.

  Next, in S102, the CPU 151a controls the motor control device 600 so as to determine the correction values C1 and C2. As a result, the motor control device 600 determines the correction values C1 and C2 by the method described above and stores them in the correction value storage unit 904. The flow in which the motor control device 600 determines the correction value will be described later.

  Thereafter, in S1003, the CPU 151a controls the motor control device 600 so that the motor is driven. As a result, the motor control device 600 starts driving the motor.

  In S1004, when the drive voltage output from the motor control unit 157 is 0 V or more (duty ratio (DR) is 50% or more), the process proceeds to S1005. In step S1005, the detection control unit 901 controls the detection value generation unit 902 to generate the detection value Isns by sampling the voltage value Vsns during the high period. As a result, the detection value generation unit 902 samples the voltage value Vsns during the high period to generate the detection value Isns.

  Thereafter, in S1006, the detection control unit 901 controls the correction control unit 903 so as to correct the generated detection value Isns with the correction value C1 stored in the correction value storage unit 904 in S1002. As a result, the correction control unit 903 corrects the detection value Isns by adding the correction value C1 (C1 <0) to the acquired detection value Isns. Then, the correction control unit 903 outputs the corrected current value Iα. Thereafter, the CPU 151a advances the process to S1007.

  If the drive voltage output from the motor control unit 157 is negative (duty ratio is less than 50%) in S1004, the process proceeds to S1008. In S1008, the detection control unit 901 controls the detection value generation unit 902 so as to generate the detection value Isns by sampling the voltage value Vsns during the low period. As a result, the detection value generation unit 902 samples the voltage value Vsns during the low period to generate the detection value Isns.

  In step S <b> 1009, the detection control unit 901 controls the detection value generation unit 902 to perform inversion processing that inverts the polarity of the generated detection value Isns (that is, the polarity of the voltage value Vsns). As a result, the detection value generation unit 902 inverts the polarity of the generated detection value Isns (that is, the polarity of the voltage value Vsns).

  After that, in S1010, the detection control unit 901 controls the correction control unit 903 so as to correct the generated detection value Isns with the correction value C2 stored in the correction value storage unit 904 in S1002. As a result, the correction control unit 903 corrects the detection value Isns by adding the correction value C2 (C1> 0) to the detection value Isns after the inversion process. Then, the correction control unit 903 outputs the corrected current value Iα. Thereafter, the CPU 151a advances the process to S1007.

  Thereafter, the motor control device 600 repeatedly performs the above-described control until the CPU 151a outputs an enable signal 'L' to the motor control device 600.

  FIG. 13 is a flowchart illustrating a method in which the motor control device 600 determines a correction value in S1002 illustrated in FIG. Hereinafter, a method in which the motor control device 600 determines the correction value will be described with reference to FIG. The processing of this flowchart is executed by the motor control device 600 that has received an instruction from the CPU 151a.

  In S2001, the CPU 151a controls the PWM generator 203 so that a current corresponding to a duty ratio of 50% flows through the motor winding. The PWM generator 203 generates a PWM signal having a duty ratio of 50% based on the triangular wave carrier wave generated by the carrier wave generation unit 522, and outputs the PWM signal to the motor drive circuit 50a. The motor drive circuit 50a supplies a current corresponding to the PWM signal output from the PWM generator 203 to the motor windings.

  Next, in S2002, the detection value generator 902 samples the voltage value Vsns in the high period. Thereafter, the detection value generator 902 generates a current value based on the sampled voltage value Vsns and outputs the current value to the correction value generation unit 905.

  In S2003, when the predetermined time T1 has not elapsed since the sampling in the high period was started, the CPU 151a returns the process to S2002.

  In S2003, when the predetermined time T1 has elapsed since the sampling in the high period was started, in S2004, the inversion control unit 521 causes the triangular wave carrier wave output from the carrier wave inversion unit 523 to be input to the comparator 203a. The changeover switch 525 is controlled. As a result, a current based on the triangular wave carrier wave having a phase opposite to that of the triangular wave carrier wave generated by the carrier wave generating unit 522 is supplied to the winding.

  After that, when a predetermined time T2 has elapsed since the inversion control unit 521 controls the changeover switch 525 so that the triangular wave carrier wave output from the carrier wave inversion unit 523 is input to the comparator 203a in S2005, the CPU 151a performs the process in S2006. Proceed to

  Next, in S2006, the detection value generator 902 samples the voltage value Vsns in the low period. Thereafter, the detection value generator 902 generates a current value based on the sampled voltage value Vsns and outputs the current value to the correction value generation unit 905.

  In S2007, when the predetermined time T1 has not elapsed since the sampling in the low period was started, the CPU 151a returns the process to S2006.

  In S2007, when a predetermined time T1 has elapsed since the sampling in the low period was started, in S2008, the CPU 151a controls the PWM generator 203 to end the supply of current. As a result, supply of current to the motor winding ends.

  Next, in S2009, the correction value generation unit 905 generates the correction values C1 and C2 by the method described above based on the current value output from the detection value generation unit 902.

  After that, in S2010, the correction value generation unit 905 stores the generated correction values C1 and C2 in the correction value storage unit 904.

  As described above, the motor control device 600 determines the correction value.

  As described above, in the present embodiment, the current corresponding to the PWM signal supplied to the winding and having a duty ratio of 50% is detected, and the motor is driven based on the detected current value. A correction value for correcting the detected current value is determined. Specifically, after detecting a current corresponding to a PWM signal having a duty ratio of 50% in the high period, the phase of the triangular wave carrier wave is inverted. Thereafter, the current corresponding to the PWM signal having a duty ratio of 50% based on the triangular wave carrier wave whose phase is inverted is also detected in the low period. Thus, by inverting the phase of the triangular wave carrier wave, the current can be detected at a constant period. Further, by correcting the current value detected during the period of driving the motor based on the determined correction value, distortion generated in the detected current waveform can be reduced. As a result, it is possible to prevent the motor control from becoming unstable.

  In the present embodiment, the sampling of the voltage value Vsns is performed in the high period or the low period based on whether the duty ratio is equal to or greater than a predetermined value, specifically, whether it is equal to or greater than 50%. However, this is not the case. For example, it may be determined whether the sampling of the voltage value Vsns is performed in the high period or the low period based on whether the duty ratio is 70% or more. In this case, the correction values C1 and C2 are determined based on the current value in a state where the duty ratio is 70%.

  In the present embodiment, the correction values C1 and C2 are determined each time the motor control device is operated, but this is not restrictive. For example, when the user gives an instruction to determine the correction values C1 and C2 from the display unit of the operation unit 152, the correction values C1 and C2 may be determined.

  In this embodiment, a stepping motor is used as a motor for driving a load, but another motor such as a DC motor may be used. Further, the embodiment is not limited to the case where the motor is a two-phase motor, and may be another motor such as a three-phase motor.

  In this embodiment, when determining the correction value, the current value is detected in the low period after the current value is detected in the high period, but this is not restrictive. For example, the current value may be detected in the high period after the current value is detected in the low period.

In the vector control in the present embodiment, the motor 509 is controlled by performing phase feedback control, but the present invention is not limited to this. For example, the motor 509 may be controlled by feeding back the rotational speed ω of the rotor 402. Specifically, as shown in FIG. 14, a speed determiner 514 is provided inside the motor control device, and the speed determiner 514 determines the rotational speed ω based on the time change of the rotational phase θ output from the phase determiner 513. decide. It should be noted that equation (13) is used to determine the speed.
ω = dθ / dt (13)

  Then, the CPU 151a outputs a command speed ω_ref that represents the target speed of the rotor. Furthermore, a speed controller 500 is provided inside the motor control device, and the speed controller 500 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 speed ω and the command speed ω_ref becomes small. Output. A configuration in which the motor 509 is controlled by performing such speed feedback control may be employed.

  In addition, the present embodiment is not limited to vector control and can be applied to a configuration having a configuration for determining the rotational phase of the rotor.

  Moreover, in this embodiment, although the permanent magnet is used as a rotor, it is not limited to this.

50 Motor drive circuit Q1-Q4 FET
203 PWM generator 509 Stepping motor 530 Current value generator 600 Motor controller

Claims (19)

A first mode for detecting the current value of the drive current flowing in the motor winding, correcting the detected current value, and controlling the drive current based on the corrected current value, and a correction value for correcting the current value. A motor control device comprising: a second mode to be determined;
A drive circuit comprising a plurality of switching elements constituting an H-bridge circuit, to which the windings are connected;
A PWM signal for controlling on and off operations of the plurality of switching elements, a first level signal that is one of a high level and a low level, and a second level signal that is the other of a high level and a low level; Is generated based on a first triangular wave as a carrier wave, and a second PWM signal composed of the first level signal and the second level signal is generated as the first PWM signal. Pulse generating means for generating based on a second triangular wave having a phase opposite to the phase of the triangular wave of
In the first mode, the current value of the drive current supplied to the winding by the drive circuit in response to the first PWM signal is detected at a timing determined by the duty ratio of the first PWM signal, and detected. Correction means for correcting the current value;
Have
The correction means detects the current value of the drive current once for each period of the first triangular wave,
Further, the correction means, in the second mode, the current value of the drive current supplied by the drive circuit to the winding in response to the first PWM signal in a state where the duty ratio is a predetermined value, Detecting the first PWM signal in a first period of the first level;
Further, in the second mode, the correction means detects the current value of the drive current in the first period, and then the drive circuit causes the second PWM signal to be in a state where the duty ratio is the predetermined value. And detecting the current value of the drive current supplied to the winding in response to the second period in which the second PWM signal is at the second level,
Further, the correction means reduces a current value detected during a period in which the first PWM signal is at the high level in the first mode based on a current value detected in the second mode. Decide
Further, the correction means increases a current value detected during a period in which the first PWM signal is at the low level in the first mode based on the current value detected in the second mode. Decide
In the first mode, when the duty ratio is larger than the predetermined value, the correction unit detects a current value of the drive current during a period in which the first PWM signal is at the high level, and detects the detected current When the value is corrected based on the first correction value and the duty ratio is smaller than the predetermined value, the current value of the drive current is detected during a period in which the first PWM signal is at the low level, and detection is performed. The corrected current value based on the second correction value,
The motor control device, wherein the pulse generation unit generates the PWM signal based on the current value corrected by the correction unit. In the second mode, the correction means detects the current value of the drive current supplied to the winding in response to the first PWM signal by the drive circuit a plurality of times, and then the drive circuit performs the second mode. Detecting the current value of the drive current supplied to the winding according to the PWM signal of the plurality of times,
Further, in the second mode, the correction means is configured to output a first average value that is an average value of a plurality of current values based on the detected first PWM signal, and the detected second PWM signal based on the detected second PWM signal. The motor control device according to claim 1, wherein the first correction value and the second correction value are determined based on a second average value that is an average value of a plurality of current values. The second correction value is a value calculated by dividing the absolute value of the difference between the first average value and the second average value by 2.
The motor control device according to claim 2, wherein the first correction value is a value obtained by inverting the polarity of the second correction value. The motor control device has control means for controlling the motor based on the current value corrected by the correction means,
The control means includes voltage generation means for generating a drive voltage for driving the drive circuit so that a deviation between the current value corrected by the correction means and the drive current to be supplied to the winding is reduced. ,
4. The pulse generation unit generates the first PWM signal based on the drive voltage generated by the voltage generation unit and the first triangular wave. 5. The motor control device according to item. The pulse generation means includes
A triangular wave generating means for generating the first triangular wave;
Inverting means for generating the second triangular wave by inverting the phase of the first triangular wave generated by the triangular wave generating means;
Comparison means for generating the PWM signal by comparing the triangular wave and the drive voltage;
The motor control device according to claim 4, comprising: When the correction means detects the drive current in the first period, the first triangular wave is first detected after the level of the first PWM signal is switched from the second level to the first level. Detect the drive current at the timing of the extreme value,
When the drive current is detected in the second period, the first triangular wave first becomes an extreme value after the level of the second PWM signal is switched from the first level to the second level. Detecting the drive current at
When the driving current is detected in the third period in which the first PWM signal is at the second level, the level of the second PWM signal is switched from the first level to the second level. The drive current is detected at a timing when the second triangular wave first becomes an extreme value,
When the driving current is detected in the fourth period in which the second PWM signal is at the first level, the level of the second PWM signal is switched from the second level to the first level. 6. The motor control device according to claim 1, wherein the drive current is detected at a timing at which the second triangular wave first becomes an extreme value. When the first PWM signal is at the first level, the plurality of switching elements are turned on,
When the first PWM signal is at the second level, the plurality of switching elements are turned off,
When the second PWM signal is at the first level, the plurality of switching elements are turned on,
When the second PWM signal is at the second level, the plurality of switching elements are turned off,
The correction means detects the polarity of the drive current when the drive current is detected during a period in which the first PWM signal is at the first level or a period in which the second PWM signal is at the first level. In the case where the drive current is detected during a period in which the first PWM signal is at the second level or a period in which the second PWM signal is at the second level without being inverted, the polarity of the detected drive current The motor control device according to claim 1, wherein the motor control device is reversed.   The motor control device according to claim 1, wherein the predetermined value is 50%. The drive circuit is
One end of the first switching element and one end of the second switching element are connected to a power source;
One end of a third switching element is connected in series to the other end of the first switching element,
One end of a fourth switching element is connected in series to the other end of the second switching element,
A resistor is connected to the other end of the third switching element and the other end of the fourth switching element,
The resistor is grounded;
One end of the winding of the motor is connected to a conductor connecting the first switching element and the third switching element, and the other end is connected to a conductor connecting the second switching element and the fourth switching element. The motor control device according to claim 1, wherein the motor control device is a circuit that has been configured. The PWM signal generated by the comparison means is supplied to the first switching element and the fourth switching element,
10. The motor control device according to claim 9, wherein a PWM signal having a phase opposite to that of the PWM signal generated by the comparison unit is supplied to the second switching element and the fourth switching element. . The control means includes
Induction for determining the induced voltage induced in the first phase winding of the motor and the second phase winding of the motor by the rotation of the rotor of the motor based on the current value corrected by the correction means. Voltage determining means;
Phase determining means for determining a rotational phase of a rotor of the motor based on the induced voltage of the first phase and the induced voltage of the second phase determined by the induced voltage determining means;
Have
The control means rotates based on the rotational phase determined by the phase determining means so that a deviation between a command phase representing a target phase of the rotor and a rotational phase determined by the phase determining means is small. A current component of a current value represented in a coordinate system, based on a value of a torque current component that generates torque in the rotor and a value of an excitation current component that affects the strength of magnetic flux passing through the winding of the motor The motor control device according to claim 1, wherein the drive current flowing through the winding is controlled. The control means includes
Induction for determining the induced voltage induced in the first phase winding of the motor and the second phase winding of the motor by the rotation of the rotor of the motor based on the current value corrected by the correction means. Voltage determining means;
Phase determining means for determining a rotational phase of a rotor of the motor based on the induced voltage of the first phase and the induced voltage of the second phase determined by the induced voltage determining means;
Speed determining means for determining the rotational speed of the rotor;
Have
The control means rotates based on the rotational phase determined by the phase determining means so that a deviation between a command speed representing a target speed of the rotor and a rotational speed determined by the speed determining means is small. A current component of a current value represented in a coordinate system, based on a value of a torque current component that generates torque in the rotor and a value of an excitation current component that affects the strength of magnetic flux passing through the winding of the motor The motor control device according to claim 1, wherein the drive current flowing through the winding is controlled. The motor driving device is
A first motor drive circuit provided with a first phase winding of the motor;
A second motor drive circuit provided with a second phase winding of the motor;
The motor control device according to claim 1, comprising: A transport roller for transporting the sheet;
A motor for driving the transport roller;
The motor control device according to any one of claims 1 to 13,
Have
The sheet conveying apparatus, wherein the motor control apparatus controls driving of a motor that drives the conveying roller. A sheet conveying device according to claim 14,
A document stacking unit for loading documents,
Have
An original feeding apparatus, wherein the original loaded on the original stacking unit feeds the original. A document feeder according to claim 15;
Reading means for reading the document fed by the document feeding device;
A document reading apparatus comprising: A sheet conveying device according to claim 14,
Image forming means for forming an image on a recording medium;
Have
The image forming apparatus, wherein the image forming unit forms an image on the recording medium conveyed by the sheet conveying apparatus. 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 18, wherein the load is a conveyance roller that conveys the recording medium.

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