JP7005733B2 - Motor control device, sheet transfer device, and image forming device - Google Patents

Description

The present invention relates to anomaly detection of motor rotation in a motor control device, a sheet transfer device , and an image forming device.

Conventionally, as a method for controlling a motor, a control method called vector control is known in which the motor is controlled by controlling a current value in a rotating coordinate system based on the rotation phase of the rotor of the motor. Specifically, for example, the motor is controlled by performing phase feedback control that controls the current value so that the deviation between the command phase of the rotor and the rotation phase becomes small. There is also a method of controlling the motor by performing speed feedback control for controlling the current value so that the deviation between the command speed of the rotor and the rotation speed becomes small.

When vector control is used, the drive current supplied to the windings of the motor is the current component (q-axis current) that generates torque for the rotor to rotate, and the current component (d-axis) that affects the magnetic flux strength of the rotor. It can be controlled separately from the current). As a result, even if the load torque applied to the rotor changes, the torque required for rotation can be efficiently generated by controlling the q-axis current according to the change in the load torque. That is, an uncontrollable state (step-out state) in which the load torque applied to the rotor exceeds the output torque corresponding to the drive current supplied to the winding of the motor, which has been a problem in the past, and the motor does not synchronize with the input signal. Can be prevented from becoming. In addition, it is possible to suppress an increase in power consumption and an increase in motor noise due to excess torque.

Vector control requires a configuration that estimates the phase of the rotor. Patent Document 1 describes an estimation method for estimating the phase of a rotor by calculating the inverse tangent of the ratio of the induced voltage generated in the winding of the motor.

However, the magnitude of the induced voltage generated in the winding becomes smaller as the rotation speed of the rotor becomes smaller. If the magnitude of the induced voltage generated in the winding is not large enough to estimate the phase of the rotor, it may not be possible to perform phase estimation with high accuracy. That is, if the rotation speed of the rotor is low, it may not be possible to accurately estimate the phase of the rotor.

In Patent Document 2, when the command speed of the rotor is smaller than a predetermined rotation speed, the motor is controlled by controlling the drive current so that the magnitude of the drive current supplied to the winding is constant. Use constant current control (open control). In the constant current control, neither the phase feedback control nor the speed feedback control is performed. Further, when the command speed is equal to or higher than the predetermined rotation speed, the above-mentioned vector control is used.

Patent No. 5537565 JP-A-2005-39955

In motor control, if the load torque applied to the rotor exceeds the output torque corresponding to the drive current supplied to the winding, the motor may be out of step. Therefore, there has been a demand for a configuration that can accurately determine an abnormality in the rotation of the motor in the control of the motor.

In view of the above problems, the present invention is a motor control device that determines the rotation speed of the rotor of the motor in the first control mode in which the drive current flowing through the windings of the motor is controlled by supplying a constant current to the windings of the motor. The purpose is to provide .

In order to solve the above problems, the motor control device according to the present invention is
In a motor control device that accelerates the rotor of a motor to a predetermined speed
A detection means for detecting the drive current flowing through the winding of the motor, and
A speed determining means for determining the rotation speed of the rotor based on the drive current detected by the detecting means, and a speed determining means.
A phase determining means for determining the rotational phase of the rotor and
A first control mode for controlling the drive current flowing through the winding by supplying a constant current to the winding, and a current represented in a rotating coordinate system based on a rotation phase determined by the phase determining means. A second control mode for performing vector control for controlling the drive current flowing through the winding based on the current component of the value is provided, and the rotation speed of the rotor is provided in a state where the first control mode is being executed. When the value corresponding to is changed from a value smaller than the first threshold value to a value larger than the first threshold value, the control mode for controlling the drive current flowing through the winding is changed from the first control mode to the first control mode. A control means for switching to the control mode of 2 and
Have,
The speed determining means of the rotor is in a state where the control means performs the first control mode and the value corresponding to the rotation speed of the rotor is larger than the second threshold value smaller than the first threshold value. Determine the rotation speed,
The first threshold value and the second threshold value are characterized in that they are smaller than the values corresponding to the predetermined speeds .

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a motor control device that determines the rotational speed of a rotor of a motor in a first control mode in which a constant current is supplied to a winding of the motor to control a drive current flowing through the winding. be able to.

It is sectional drawing explaining the image forming apparatus which concerns on 1st Embodiment. It is a block diagram which shows the control structure of the image forming apparatus. It is a block diagram which shows the structure of the motor control device which concerns on 1st Embodiment. It is a figure which shows the relationship between the 2 phase motor which consists of A phase and B phase, and d-axis and q-axis of a rotating coordinate system. It is a figure which shows the relationship between the command speed ω_ref, the estimated rotation speed ω, the switching threshold value ωth, and the step-out determination step-out determination threshold value ωsnl in the first embodiment. It is a figure explaining the step-out determination method in 1st Embodiment. It is a flowchart which shows the drive control method of the motor using the said motor control device. It is a flowchart which shows the step-out determination method of the motor using the abnormality determination apparatus which concerns on 1st Embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the shapes of the components and their relative arrangements described in this embodiment should be appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions, and the scope of the present invention is defined. It is not intended to be limited to the following embodiments. In the following description, the case where the motor control device is provided in the image forming apparatus will be described, but the case where the motor control device is provided is not limited to the image forming apparatus. For example, the motor control device is also used as a sheet transfer device for transporting a sheet such as a recording medium or a document.

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

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

The documents loaded on the document loading section 203 of the document feeding device 201 are fed one by one by the paper feed roller 204, and are conveyed to the document glass stand 214 of the reading device 202 via the transfer guide 206. Further, the original document is conveyed at a constant speed by the conveying belt 208, and is ejected to the outside of the apparatus by the paper ejection roller 205. The reflected light from the original image illuminated by the illumination 209 at the reading position of the reading device 202 is guided to the image reading unit 101 by an optical system including reflection mirrors 210, 211, and 212, and converted into an image signal by the image reading unit 101. Will be done. The image reading unit 101 includes a lens, a CCD which is a photoelectric conversion element, a driving circuit of the CCD, and the like. The image signal output from the image reading unit 101 is output to the image printing device 301 after various correction processes are performed by the image processing unit 112 configured by a hardware device such as an ASIC. As described above, the original is read. That is, the document feeding device 201 and the reading device 202 function as a document reading device.

Further, as the reading mode of the document in the reading device 202, there are a scanning mode and a fixed reading mode. The scanning mode is a mode in which an image of a document is read while the document is conveyed at a constant speed with the illumination system 209 and the optical system fixed in a predetermined phase. The fixed reading mode is a mode in which the original is placed on the original glass 214 of the reading device 202, and the image of the original placed on the original glass 214 is read while the lighting system 209 and the optical system are moved at a constant speed. be. Normally, sheet-shaped originals are read in the scanning mode, and bound originals such as books and booklets are read in the fixed reading mode.

Sheet storage trays 302 and 304 are provided inside the image printing apparatus 301. Different types of recording media can be stored in the sheet storage trays 302 and 304. For example, the sheet storage tray 302 stores A4 size plain paper, and the sheet storage tray 304 stores A4 size thick paper. The recording medium is one in which an image is formed by an image forming apparatus, and the recording medium includes, for example, paper, a resin sheet, a 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. Further, 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 the optical scanning device 311 including the semiconductor laser and the 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, the laser beam corresponding to the image signal input from the reading device 202 to the optical scanning device 311 is photosensitive from the optical scanning device 311 via the polygon mirror and the mirrors 312 and 313. The outer peripheral surface of the drum 309 is irradiated. As a result, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 309. As the charging method of 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 by the toner in the developer 314, and the 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. At the timing of this transfer, the registration roller 308 feeds the recording medium to the transfer position.

As described above, the recording medium on which the toner image is transferred is sent to the fixing device 318 by the transport belt 317, heated and pressurized by the fixing device 318, and the toner image is fixed on the recording medium. In this way, 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 fuser 318 is ejected to an output tray (not shown) by the output 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 the paper ejection roller 319, the transport roller 320, and the reversing roller 321. Is carried to the inversion path 325. After that, the recording medium is conveyed to the registration roller 308 again 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. After that, the recording medium is ejected to an output tray (not shown) by the output rollers 319 and 324.

Further, when the recording medium on which the image is formed on the first surface is inverted so that the first surface faces downward and the paper is discharged to the outside of the image forming apparatus 100, the recording medium that has passed through the fuser 318 is discharged. It is conveyed in the direction toward the transfer roller 320 through the paper roller 319. Then, just before the rear end of the recording medium passes through the nip portion of the transport roller 320, the rotation of the transport roller 320 is reversed. As a result, with the first surface of the recording medium facing down, the recording medium can be conveyed in the direction toward the paper ejection roller 324 and ejected to the outside of the image forming apparatus 100.

The above is a description of the configuration and function of the image forming apparatus 100. The load in the present invention is an object driven by a motor. For example, various rollers (conveying rollers) such as paper feed rollers 204, 303, 305, registration rollers 308 and paper ejection rollers 319, photosensitive drums 309, transport belts 208, 317, lighting systems 209, optical systems and the like are in the present invention. Corresponds to the load. The motor control device of the present embodiment can be applied to a motor that drives these loads.

FIG. 2 is a block diagram showing 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. Further, the system controller 151 is connected to an image processing unit 112, an operation unit 152, an analog-to-digital (A / D) converter 153, a high-voltage control unit 155, a motor control device 157, 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 formation sequence by reading and executing various programs stored in the ROM 151b.

The RAM 151c is a storage device. The RAM 151c stores, for example, 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.

The system controller 151 transmits the set value data of various devices provided inside the image forming apparatus 100, which is necessary for the image processing in the image processing unit 112, to the image processing unit 112. Further, the system controller 151 receives the signal from the sensors 159 and sets the set value of the high voltage control unit 155 based on the received signal. The high-voltage control unit 155 supplies the voltage required for the high-voltage unit 156 (charger 310, developer 314, transfer charger 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 and converts the detection signal from an analog signal to a digital signal and transmits the detection signal 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 required for performing the fixing process. The fixing heater 161 is a heater used for the fixing process, and is included in the fixing device 318.

The system controller 151 displays an operation screen for the user to set the type of recording medium to be used (hereinafter referred to as a 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 paper type 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. Further, 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 such as the number of images formed, whether or not an image is being formed, the occurrence of jam, and the location where the jam occurs. The operation unit 152 displays the 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 this embodiment will be described. The motor control device in the present embodiment can control the motor by any control method of vector control (second control mode) and constant current control (first control mode). In the following description, a stepping motor is used as the motor for driving the load, but the present invention is not limited to this. Further, the motor is not always a two-phase motor. Further, it is assumed that the motor in the present embodiment is not provided with a sensor such as a rotary encoder for detecting the rotation phase of the rotor of the motor.

FIG. 3 is a block diagram showing an example of the configuration of a motor control device 157 that controls the drive of a stepping motor (hereinafter referred to as a motor) 509. The motor control device 157 in the present embodiment is provided with a constant current controller 517 that performs constant current control and a vector controller 518 that performs vector control. Further, in the motor control device 157, whether the constant current controller 517 is used to control the drive of the motor 509 or the vector controller 518 is used to control the drive of the motor 509 is determined by the command speed of the rotor 402. There is a configuration to switch based on. Specifically, a control switch (control switching means) 515, a control switching switch (control switching means) 516a, 516b, 516c (hereinafter referred to as each switch) and the like are provided. The motor control means in the present embodiment corresponds to the constant current controller 517, the vector controller 518, the control switch 515, and the switches 516a, 516b, and 516c. Further, the first control circuit in the present embodiment corresponds to a circuit that controls the drive of the motor 509 by using the constant current controller 517. Further, the second control circuit in the present embodiment corresponds to a circuit that controls the drive of the motor 509 by using the vector controller 518. The motor control device in the present embodiment has a part (current controller 503, PWM inverter 506, etc.) that is partially shared between the circuit that performs vector control and the circuit that performs constant current control, but this is limited. is not it. For example, a circuit that performs vector control and a circuit that performs constant current control may be provided independently.

First, a method in which the motor control device 157 in the present embodiment performs vector control will be described with reference to FIGS. 3 and 4.

FIG. 4 is a diagram showing the relationship between the motor 509 composed of two phases, 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 static 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. Further, the angle formed by the α axis in the rest coordinate system and the direction of the magnetic flux created by the magnetic poles of the permanent magnet used in the rotor 402 (d-axis direction) is defined as θ. The rotation phase of the rotor 402 is represented by an angle θ. In vector control, the motor 509 is represented by a d-axis along the magnetic flux direction of the rotor 402 and a q-axis along a direction 90 degrees counterclockwise from the d-axis (perpendicular to the d-axis). A rotation coordinate system based on the rotation phase θ of the rotor 402 is used.

Vector control is a control method for controlling a motor by controlling a current value in a rotating coordinate system based on the rotation phase of the rotor of the motor. Specifically, for example, the motor is controlled by performing phase feedback control that controls the current value so that the deviation between the command phase of the rotor and the rotation phase becomes small. There is also a method of controlling the motor by performing speed feedback control for controlling the current value so that the deviation between the command speed of the rotor and the rotation speed becomes small. The current value in the rotational coordinate system is the current value of the q-axis component (torque current component) that generates torque in the rotor of the motor and the d-axis component (exciting current component) that affects the magnetic flux strength of the rotor of the motor. Corresponds to the current value.

The motor control device 157 is provided with a phase controller 502, a current controller (voltage generation means) 503, a coordinate inverse converter 505, a coordinate converter 511, a PWM inverter 506, and the like as circuits for performing vector control. The coordinate converter (coordinate conversion means) 511 transfers the current vector corresponding to the drive current flowing through the windings of the A phase and the B phase of the motor 509 from the static coordinate system represented by the α axis and the β axis to the q axis and the q axis. Coordinates are converted to a rotating coordinate system represented by the d-axis. As a result, the drive current supplied to the A-phase and B-phase windings of the motor 509 is the current value of the q-axis component (q-axis current) and the current value of the d-axis component (d-axis current) in the rotating coordinate system. Can be expressed using. The q-axis current corresponds to the torque current that generates torque in the rotor 402 of the motor 509. Further, the d-axis current corresponds to an exciting current that affects the magnetic field strength 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 current and the d-axis current. That is, the torque required for the rotor 402 to rotate can be efficiently generated.

The motor control device 157 estimates the rotation phase 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 151a (upper device) generates a command value (command phase) θ_ref of the rotation phase of the rotor 402 of the motor 509, and outputs the command phase θ_ref to the motor control device 157 in a predetermined time cycle.

The phase controller (phase 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 rotation phase θ of the rotor 402 of the motor 509 and the command phase θ_ref becomes small. And output. Specifically, the phase 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 rotation phase θ of the rotor 402 of the motor 509 and the command phase θ_ref becomes zero. And output. The phase controller 502 in the present embodiment is composed of a proportional (P) and an integral (I) compensator, but is composed of a proportional (P), an integral (I), and a differential (D) compensator. May be. When a permanent magnet is used for the rotor 402, the d-axis current command value id_ref, which normally affects the magnetic flux strength of the rotor 402, is set to 0, but the present invention is not limited to this.

Next, the drive current flowing through the A-phase and B-phase windings of the motor 509 is detected by the current detectors (current detection means) 507 and 508, and then from the analog value to the digital value by the A / D converter 510. Is converted to.

The drive current flowing through the A-phase and B-phase windings of the motor 509 is converted from an analog value to a digital value by the A / D converter 510, and is used as the current values iα and iβ in the static coordinate system of the rotor 402. It is expressed by the following equation using the rotation phase θ.

iα = I * cosθ (1)
iβ = I * sinθ (2)
These current values iα and iβ are input to the coordinate converter 511 and the induced voltage calculator (induced voltage determining means) 512.

In the coordinate converter 511, the current values iα and iβ are coordinate-converted 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 equation.

id = cosθ * iα + sinθ * iβ (3)
iq = -sinθ * iα + cosθ * iβ (4)
As described above, the coordinate converter 511 transfers the current vector corresponding to the drive current flowing through the windings of the A phase and the B phase of the motor 509 from the stationary coordinate system represented by the α axis and the β axis to the q axis and the q axis. Coordinates are converted to a rotating coordinate system represented by the d-axis.

Subsequently, the deviation between the current value iq obtained by the coordinate conversion by the coordinate converter 511 and iq_ref output from the phase controller 502 and the deviation between the current value id and the id_ref output from the phase controller 502 are It is output to the current controller 503, respectively. The current controller 503 generates the current values iq * and id * so that the deviations become smaller, respectively. Specifically, the current controller 503 generates the current values iq * and id * so that the deviations become 0, respectively. After that, the current controller 503 generates drive voltages Vq and Vd corresponding to the respective current values iq * and id * and outputs them to the coordinate inverse converter (coordinate inverse conversion means) 505. The current controller 503 in the present embodiment is composed of a proportional (P) and an integral (I) compensator like the phase controller 502, but the proportional (P), the integral (I), and the derivative (D). ) It may be composed of a compensator.

The coordinate inverse 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 static coordinate system by the following equation.

Vα = cosθ * Vd-sinθ * Vq (5)
Vβ = sinθ * Vd + cosθ * Vq (6)
The coordinate inverse converter 505 reversely converts the drive voltages Vq and Vd in the rotating coordinate system into the drive voltages Vα and Vβ in the static coordinate system, and then converts Vα and Vβ into the induced voltage calculator 512 and the PWM inverter (supply means) 506. Output to. In the present embodiment, the drive voltages Vq and Vd corresponding to the current values iq * and id * are generated, and the drive voltages Vα and Vd in the quiescent coordinate system are obtained by inversely transforming the drive voltages Vq and Vd. I got it, but this is not the case. For example, the current values iq * and id * are inversely transformed into the current values iα * and iβ * in the static coordinate system to generate the drive voltages Vα and Vβ corresponding to the current values iα * and iβ *. Is also good.

The PWM inverter 506 has a full bridge circuit. The full bridge circuit is driven by 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 supplies the drive currents iα and iβ to the windings of each phase of the motor 509 to drive the motor 509. .. In the present embodiment, the PWM inverter has a full bridge circuit, but may be a half bridge circuit or the like.

Next, a method of estimating the rotation phase θ of the rotor 402 will be described. For the estimation of the rotation phase θ of the rotor 402, the values of the induced voltages Eα and Eβ induced in the windings of the A phase and the B phase 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, from the current values iα and iβ input from the A / D converter 510 to the induced voltage calculator 512 and the drive voltages Vα and Vβ input from the coordinate inverse converter 505 to the induced voltage calculator 512. , The induced voltages Eα and Eβ are calculated by the following equations.

Eα = Vα-R * iα-L * diα / dt (7)
Eβ = Vβ-R * iβ-L * diβ / dt (8)
Here, R is the winding resistance and L is the winding inductance. The values of R and L are unique to the motor 509 used, and are stored in advance in a memory (not shown) 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 phase estimator (phase determining means) 513. The phase estimator 513 estimates the rotational phase θ of the rotor 402 of the motor 509 from the ratio of the induced voltage Eα of the A phase and the induced voltage Eβ of the B phase by the following equation.

θ = tan ^ -1 (-Eβ / Eα) (9)
The rotational phase θ of the rotor 402 obtained as described above is input to the phase controller 502, the coordinate inverse converter 505, the coordinate converter 511, and the speed estimator (speed determining means) 514. After that, the above-mentioned control is repeated.

As described above, the motor control device 157 controls the motor 509 using vector control. By controlling the drive of the motor using vector control, it is possible to suppress the motor from being out of step, the increase in motor noise due to the excess torque, and the increase in power consumption. In the vector control in the present embodiment, the motor 509 is controlled by performing the above-mentioned phase feedback control, but the present invention is not limited to this. For example, the rotation speed ω of the rotor 402 may be fed back to control the drive of the motor 509. Specifically, the speed estimator estimates the rotation speed ω based on the time change of the rotation phase θ output from the phase estimator 513. The following equation is used to estimate the velocity.

ω = dθ / dt (10)
Further, the CPU 151a outputs the command speed ω_ref of the rotor. Further, a speed controller (speed control means) is provided inside the motor control device, and the q-axis current command value iq_ref and the d-axis current command are provided so that the deviation between the rotation speed ω and the command speed ω_ref becomes small. The value id_ref is generated and output. The drive of the motor 509 may be controlled by performing the speed feedback control as described above.

However, the magnitude of the induced voltage generated in the winding becomes smaller as the rotation speed of the rotor becomes smaller. If the magnitude of the induced voltage generated in the winding is not large enough to estimate the phase of the rotor, it may not be possible to perform phase estimation with high accuracy. That is, if the rotation speed of the rotor is low, it may not be possible to accurately estimate the phase of the rotor. As a result, the drive control of the motor may become unstable.

As shown in FIG. 3, the motor control device 157 in the present embodiment is provided with a configuration for switching between constant current control and vector control. Specifically, a control switch 515, switches 516a, 516b, 516c and the like are provided.

Further, FIG. 5 is a diagram showing the relationship between the command speed ω_ref, the estimated rotation speed ω, the switching threshold value ωth (second threshold value), and the step-out determination threshold value ωsnl (first threshold value) in the present embodiment. .. The switching threshold value ωth and the step-out determination threshold value ωsnl will be described later. Further, the relationship between the command speed ω_ref shown in FIG. 5, the estimated rotation speed ω, the switching threshold value ωth, and the step-out determination threshold value ωsnl is an example, and is not limited thereto.

Hereinafter, a control switching method between constant current control and vector control in the present embodiment will be described with reference to FIGS. 3 and 5.

In the present embodiment, the switching threshold value ωth of the rotation speed of the rotor 402 for switching between the constant current control and the vector control is set. When switching the drive control of the motor from the constant current control to the vector control, the rotation speed of the motor may decrease momentarily. This was caused by the first drive current supplied to the rotor after the motor drive control was switched, rather than the magnitude of the torque generated by the last drive current supplied to the rotor before the motor drive control was switched. This is because the magnitude of the torque may be smaller. Therefore, if the switching threshold ωth is set to the smallest rotation speed (hereinafter referred to as estimable speed) among the rotation speeds at which the rotation phase can be estimated accurately, when the rotation speed decreases momentarily at the time of control switching. , Motor control by vector control becomes unstable. Therefore, it is effective that the switching threshold value ωth is set to a rotation speed larger than the estimated speed in consideration of the decrease in the rotation speed.

As shown in FIG. 3, the CPU 151a outputs the command speed ω_ref of the rotor of the motor 509 to the control switch 515 and the abnormality determining device (abnormality determining means) 519.

The control switch 515 compares the switching threshold value ωth with the command speed ω_ref. The switching threshold value ωth is stored in advance in a ROM or the like provided in the control switch 520. Further, in the present embodiment, the value of the switching threshold value ωth is set to 3 rps, but the present invention is not limited to this, and any rotation speed that can accurately estimate the rotation phase of the rotor may be used.

During control by the constant current controller 517, when the command speed ω_ref becomes the switching threshold value ωth or more (ω_ref ≧ ωth), the control switch 515 switches the controller that controls the drive of the motor 509. That is, the control switch 515 controls the state of each switch 516a, 516b, 516c so as to switch the controller that controls the drive of the motor 509 from the constant current controller 517 to the vector controller 518. As a result, vector control is performed by the vector controller 518.

Further, when the command speed ω_ref is smaller than the switching threshold value ωth (ω_ref <ωth) during the control by the constant current controller 517, the control switch 515 does not switch the controller that controls the drive of the motor 509. That is, the control switch 515 controls the state of each switch 516a, 516b, 516c so that the drive of the motor 509 is controlled by the constant current controller 517. As a result, the constant current control by the constant current controller 517 is continued.

During control by the vector controller 518, when the command speed ω_ref becomes smaller than the switching threshold value ωth (ω_ref <ωth), the control switch 515 switches the controller that controls the drive of the motor 509. That is, the control switch 515 controls the state of each switch 516a, 516b, 516c so as to switch the controller that controls the drive of the motor 509 from the vector controller 518 to the constant current controller 517. As a result, constant current control is performed by the constant current controller 517.

Further, when the command speed ω_ref is equal to or higher than the switching threshold value ωth (ω_ref ≧ ωth) during the control by the vector controller 518, the control switch 515 does not switch the controller that controls the drive of the motor 509. That is, the control switch 515 controls the state of each switch 516a, 516b, 516c so that the drive of the motor 509 is controlled by the vector controller 518. As a result, the vector control by the vector controller 518 is continued. In the present embodiment, the control is switched based on the command speed ω_ref output from the CPU 151a, but this is not the case. For example, the speed estimator calculates the command speed ω_ref of the rotor of the motor 509 based on the time change of the command value θ_ref output from the CPU 151a. The control may be switched based on the command speed ω_ref calculated by the speed estimator. It is assumed that the equation (10) is used for the calculation.

Further, in the present embodiment, when determining whether to switch the motor drive control from the constant current control to the vector control, the rotation command speed ω_ref and the switching threshold ωth are compared, but the rotation command speed ω_ref is not used. The rotation speed ω may be used. For example, the rotation speed ω of the rotor may be estimated using the equation (10) based on the time change of the rotation phase θ output from the phase estimator, and the rotation speed ω and the switching threshold ωth may be compared. good.

Next, constant current control will be described with reference to FIG. The constant current control is a control method for controlling the motor by controlling the drive current so that the magnitude of the drive current supplied to the winding of the motor becomes constant. In the constant current control, neither the phase feedback control nor the speed feedback control is performed.

The CPU 151a outputs the command phase θ_ref to the constant current controller 517 provided in the motor control device 157. The constant current controller 517 generates and outputs the command values iα_ref and iβ_ref of the current in the rest coordinate system corresponding to the command phase θ_ref output from the CPU 151a. In this embodiment, the command phase θ_ref is used when the constant current control is performed, but this is not the case. For example, the command speed ω_ref is output to the constant current controller, and the constant current controller generates and outputs the command values iα_ref and iβ_ref of the current in the rest coordinate system corresponding to the command speed ω_ref. Is also good.

Next, the current detectors 507 and 508 detect the drive current flowing through the windings of the A phase and the B phase of the motor 509. After that, the detected drive current is converted from an analog value to a digital value by the A / D converter 510, and is expressed as current values iα and iβ as in the equations (1) and (2). The deviation between the current value iα and the command value iα_ref and the deviation between the current value iβ and the command value iβ_ref are input to the current controller 503. The current controller 503 generates iα ′ and iβ ′ so that the deviation becomes small, and outputs drive voltages Vα and Vβ corresponding to the respective current values iα ′ and iβ ′. Specifically, iα'and iβ' are generated so that the deviations approach 0, respectively, and the drive voltages Vα and Vβ corresponding to the respective current values iα'and iβ' are output. The drive voltages Vα and Vβ output from the current controller 503 are input to the PWM inverter 506, and the PWM inverter 506 supplies a drive current to the windings of each phase of the motor 509 to drive the motor 509 by the method described above. ..

As described above, in the control of the motor 509 by the motor control device 157 in the present embodiment, there is a period in which constant current control is performed and a period in which vector control is performed. In constant current control, the drive current supplied to the windings of the motor cannot be controlled according to the actual rotation status of the rotor, so the load torque applied to the rotor corresponds to the drive current supplied to the windings. The output torque may be exceeded and the motor may be out of step. If the motor drive is continued while the motor is out of step, problems such as abnormal noise may occur from the motor. Therefore, there is a demand for a configuration that can accurately perform step-out determination in constant current control. In this embodiment, it is assumed that the circuit that performs the vector control is operating even when the constant current control is performed. That is, it is assumed that the circuit for estimating the phase θ and the rotation speed ω of the rotor is operating even when the constant current control is performed. Further, it is assumed that the circuit that performs constant current control is operating even when vector control is being performed.

As shown in FIG. 3, the motor control device 157 in the present embodiment is provided with an abnormality determining device 519 as a configuration for determining whether or not the rotation of the motor is abnormal. In the present embodiment, the abnormality determining device 519 determines whether or not the motor is in a step-out state. In the present embodiment, the abnormality determining device is provided inside the motor control device, but the present invention is not limited to this. For example, the configuration may be provided outside the motor control device. Further, the rotation abnormality is not limited to step-out, and a state such as a lock of the rotor or a decrease in rotation speed due to an external force or the like also corresponds to a rotation abnormality.

The command speed ω_ref output from the CPU 151a and the rotation speed ω output from the speed estimator 514 are input to the abnormality determining device 519. The abnormality determining device 519 determines whether or not the motor is in a step-out state based on the command speed ω_ref and the rotation speed ω, and outputs a stop signal to the CPU 151a based on the determination result. The stop signal is a signal for determining the operation / stop of the motor control device, and when the stop signal is'H (high level)', the CPU 151a stops the motor control device. That is, the motor is stopped. Further, when the stop signal is'L (low level)', the operation of the motor control device is continued. That is, the driving of the motor is continued.

In order to make an accurate step-out determination, it is necessary to accurately estimate the rotation speed ω. That is, it is necessary to estimate the rotation phase with high accuracy. In the present embodiment, the step-out determination threshold value ωsnl, which is the threshold value of the rotation speed for performing the step-out determination, is set to the estimable speed. That is, the step-out determination threshold value ωsnl is set to a value equal to or less than the switching threshold value ωth. As a result, even in a state where control by constant current control is performed, step-out determination can be performed if the rotation speed ω is equal to or higher than the threshold value ωsnl.

The abnormality determination device 519 compares the command speed ω_ref with the step-out determination threshold value ωsnl. The step-out determination threshold value ωsnl is stored in advance in a ROM or the like provided in the abnormality determination device 519. The abnormality determination device 519 does not perform step-out determination when the command speed ω_ref is smaller than the step-out determination threshold value ωsnl (ω_ref <ωsnl), and does not perform step-out determination when the command speed ω_ref is greater than or equal to the step-out determination threshold value ωsnl (ω_ref ≧ ωsnl). Make a step-out judgment.

Next, a method of detecting the step-out of the motor by the abnormality determining device 519 will be described with reference to FIG.

FIG. 6 is a diagram illustrating a step-out determination method in the present embodiment. As described above, in the step-out determination of the present embodiment, the command speed ω_ref of the rotor 402 and the actual rotation speed ω are used. Specifically, when the value obtained by dividing the deviation between the command speed ω_ref and the rotation speed ω by the command speed ω_ref (hereinafter referred to as Δ) is a value within a predetermined range, the abnormality determiner 519 is a stop signal'. L'is output to the CPU 151a. If the Δ is not within a predetermined range, the abnormality determining device 519 determines that the motor is in a step-out state, and outputs the stop signal ‘H’ to the CPU 151a. In the present embodiment, when the Δ is not within a predetermined range, the abnormality determining device 519 determines that the motor is in a step-out state, but this is not the case. For example, the abnormality determining device 519 may be configured to determine that the motor is in a step-out state when the state in which the Δ is not within a predetermined range continues for a predetermined period. That is, even if the Δ is out of the predetermined range, if the Δ is within the predetermined range within the predetermined period, the abnormality determining device 519 determines that the motor is out of step. It may be configured not to. Further, in the present embodiment, the value of Δ from −0.2 to +0.2 is set as a value within the predetermined range, but this is not the case. Further, in the present embodiment, the step-out determination is performed based on the value obtained by dividing the deviation between the command speed ω_ref and the rotation speed ω by the command speed ω_ref, but this is not the case. For example, the step-out determination may be performed based on the deviation between the command speed ω_ref and the rotation speed ω. Further, in the present embodiment, the step-out determination is performed based on the command speed ω_ref and the rotation speed ω, but the step-out determination is not limited to this, and for example, the step-out determination is performed based only on the rotation speed ω. It may be configured.

FIG. 7 is a flowchart showing a motor drive control method using the motor control device 157. Hereinafter, the drive control of the motor 509 according to the present embodiment will be described with reference to FIG. 7. The processing of this flowchart is executed by the motor control device 157 instructed by the CPU 151a.

First, the CPU 151a outputs the enable signal ‘H’ to the motor control device 157, so that the motor control device 157 starts the drive control of the motor 509 based on the command output from the CPU 151a. The enable signal is a signal that permits or prohibits the operation of the motor control device 157. When the enable signal is'L (low level)', the CPU 151a prohibits the operation of the motor control device 157. That is, the control of the motor 509 by the motor control device 157 is terminated. When the enable signal is'H (high level)', the CPU 151a permits the operation of the motor control device 157, and the motor control device 157 controls the drive of the motor 509 based on the command output from the CPU 151a. conduct.

Next, in S1001, the control switch 515 controls the state of each switch 516a, 516b, 516c so that the drive of the motor 509 is controlled by the constant current controller 517. As a result, constant current control is performed by the constant current controller 517.

After that, when the CPU 151a outputs the enable signal ‘L’ to the motor control device 157 in S1002, the motor control device 157 ends the driving of the motor 509.

Further, in S1002, when the CPU 151a outputs the enable signal ‘H’ to the motor control device 157, the motor control device 157 advances the process to S1003.

In S1003, when the command speed ω_ref is a value smaller than the step-out determination threshold value ωsnl, the processing returns to S1001 again, and the constant current control by the constant current controller 517 is continued.

Further, in S1003, when the command speed ω_ref is a value equal to or higher than the step-out determination threshold value ωsnl, in S1004, the abnormality determination device 519 makes a step-out determination by the method described above, and the motor control device 157 advances the process to S1005. ..

In S1005, when the abnormality determining device 519 outputs the stop signal ‘H’ to the CPU 151a, the CPU 151a outputs the enable signal ‘L’ to the motor control device 157. As a result, the motor control device 157 stops driving the motor 509.

Further, in S1005, when the abnormality determining device 519 outputs the stop signal ‘L’ to the CPU 151a, the motor control device 157 advances the process to S1006.

In S1006, when the command speed ω_ref is a value equal to or higher than the switching threshold value ωth, in S1007, the control switch 515 switches the controller that controls the drive of the motor 509. That is, the control switch 515 controls the state of each switch 516a, 516b, 516c so as to switch the controller that controls the drive of the motor 509 from the constant current controller 517 to the vector controller 518. As a result, vector control is performed by the vector controller 518. After that, the process returns to S1002 again.

Further, in S1006, when the command speed ω_ref is a value smaller than the switching threshold value ωth, the processing returns to S1001 again, and the constant current control by the constant current controller 517 is continued.

After that, the motor control device 157 repeats the above-mentioned control until the CPU 151a outputs the enable signal ‘L’ to the motor control device 157, and controls the drive of the motor 509.

FIG. 8 is a flowchart showing a step-out determination method of the motor 509 using the abnormality determination device 519. Hereinafter, the step-out determination method in the present embodiment will be described with reference to FIG. The processing of this flowchart is executed by the abnormality determination device 519.

First, in S2001, the abnormality determining device 519 calculates the Δ and advances the process to S2002.

In S2002, when the Δ is a value within a predetermined range, in S2003, the abnormality determining device 519 outputs the stop signal ‘L’ to the CPU 151a. Further, in S2002, when the Δ is a value outside the predetermined range, in S2004, the abnormality determining device 519 outputs the stop signal ‘H’ to the CPU 151a.

After that, the abnormality determining device 519 repeats the above-mentioned method every time the step-out determination is performed. It is assumed that the stop signal ‘L’ is output to the CPU 151a during the period from the start of the motor drive control until the step-out determination is performed.

As described above, in the present embodiment, the step-out determination threshold value ωsnl is set to the presumable speed. That is, the step-out determination threshold value ωsnl is set to be equal to or less than the switching threshold value ωth. As a result, the step-out determination can be started as soon as possible. Specifically, the step-out determination can be accurately performed even when the constant current control is being performed. In addition, by configuring the motor to stop when the motor is in the step-out state, abnormal noise may be generated from the motor due to the attempt to drive the motor in the step-out state. It can be suppressed. Further, since the step-out determination is performed even during the vector control, the motor can be stopped even if the motor step-out during the vector control by any chance due to a sudden load fluctuation or the like. That is, it is possible to suppress the generation of abnormal noise from the motor due to the attempt to drive the motor in a state where the motor is out of step.

In the vector control in the present embodiment, a rotating coordinate system based on the estimated value of the rotation phase θ of the rotor 402 is used, but the present invention is not limited to this. For example, a rotating coordinate system based on the command phase θ_ref may be used. Further, the estimation of the rotation speed ω and the rotation command speed ω_ref is not limited to the estimation using the equation (10). For example, the drive current flowing through the A-phase (or B-phase) winding of the motor 509, the A-phase (or B-phase) drive voltage, the induced voltage generated in the A-phase (or B-phase) winding, and the like, the rotor 402. Detects a periodic signal that correlates with the rotation period of. The rotation speed ω and the rotation command speed ω_ref may be estimated by detecting the period in which the magnitude of the signal becomes 0. Further, in the present embodiment, the step-out determination is performed based on the rotation speed of the rotor, but this is not the case. For example, the step-out determination may be performed based on the rotation phase of the rotor.

151a CPU
157 Motor controller 402 Rotor 506 PWM inverter 507, 508 Current detector 509 Stepping motor 513 Phase estimator 514 Speed estimator 517 Constant current controller 519 Abnormality detector

Claims (18)

In a motor control device that accelerates the rotor of a motor to a predetermined speed
A detection means for detecting the drive current flowing through the winding of the motor, and
A speed determining means for determining the rotation speed of the rotor based on the drive current detected by the detecting means, and a speed determining means.
A phase determining means for determining the rotational phase of the rotor and
A first control mode for controlling the drive current flowing through the winding by supplying a constant current to the winding, and a current represented in a rotating coordinate system based on a rotation phase determined by the phase determining means. A second control mode for performing vector control for controlling the drive current flowing through the winding based on the current component of the value is provided, and the rotation speed of the rotor is provided in a state where the first control mode is being executed. When the value corresponding to is changed from a value smaller than the first threshold value to a value larger than the first threshold value, the control mode for controlling the drive current flowing through the winding is changed from the first control mode to the first control mode. A control means for switching to the control mode of 2 and
Have,
The speed determining means of the rotor is in a state where the control means performs the first control mode and the value corresponding to the rotation speed of the rotor is larger than the second threshold value smaller than the first threshold value. Determine the rotation speed,
The motor control device , wherein the first threshold value and the second threshold value are smaller than the value corresponding to the predetermined speed . In the motor control device, the rotation speed determined by the speed determining means in a state where the control means performs the first control mode and the value corresponding to the rotation speed of the rotor is larger than the second threshold value. The motor control device according to claim 1, further comprising a determination means for determining whether or not the rotation of the motor is abnormal based on the above. The motor control device according to claim 2, wherein the abnormality corresponds to a decrease in the rotation speed of the rotor. The second control mode is a control mode in which the drive current flowing through the winding is controlled so that the deviation between the command speed representing the target speed of the rotor and the rotation speed determined by the speed determining means becomes small. The motor control device according to any one of claims 1 to 3, wherein the motor control device is characterized by the above. The second control mode is a control mode that controls the drive current flowing through the winding so that the deviation between the command phase representing the target phase of the rotor and the rotation phase determined by the phase determining means becomes small. The motor control device according to any one of claims 1 to 3, wherein the motor control device is characterized by the above. The motor control device according to any one of claims 1 to 5 , wherein the value corresponding to the rotation speed of the rotor is a speed representing the target speed of the rotor. The motor control device according to any one of claims 1 to 5 , wherein the value corresponding to the rotation speed of the rotor is the rotation speed determined by the speed determination means. The motor control device has an induced voltage determining means for determining an induced voltage induced in the winding by the rotation of the rotor based on the drive current detected by the detecting means.
The one according to any one of claims 1 to 7 , wherein the speed determining means determines the rotational speed of the rotor based on the value of the induced voltage determined by the induced voltage determining means. Motor control device. In a motor control device that accelerates the rotor of a motor to a predetermined speed
A detection means for detecting the drive current flowing through the winding of the motor, and
A phase determining means for determining the rotational phase of the rotor based on the drive current detected by the detecting means, and a phase determining means.
A first control mode for controlling the drive current flowing through the winding by supplying a constant current to the winding, and a current represented in a rotating coordinate system based on a rotation phase determined by the phase determining means. A second control mode for performing vector control for controlling the drive current flowing through the winding based on the current component of the value is provided, and the rotation speed of the rotor is provided in a state where the first control mode is being executed. When the value corresponding to is changed from a value smaller than the first threshold value to a value larger than the first threshold value, the control mode for controlling the drive current flowing through the winding is changed from the first control mode to the first control mode. A control means for switching to the control mode of 2 and
Have,
The phase determining means of the rotor is in a state where the control means performs the first control mode and the value corresponding to the rotation speed of the rotor is larger than the second threshold value smaller than the first threshold value. Determine the rotation phase,
The motor control device , wherein the first threshold value and the second threshold value are smaller than the value corresponding to the predetermined speed . In the motor control device, the rotation phase determined by the phase determining means in a state where the control means performs the first control mode and the value corresponding to the rotation speed of the rotor is larger than the second threshold value. The motor control device according to claim 9, further comprising a determination means for determining whether or not the rotation of the motor is abnormal based on the above. The motor control device according to claim 10, wherein the abnormality corresponds to a decrease in the rotation speed of the rotor. The motor control device has a speed determining means for determining the rotational speed of the rotor.
The second control mode is a control mode in which the drive current flowing through the winding is controlled so that the deviation between the command speed representing the target speed of the rotor and the rotation speed determined by the speed determining means becomes small. The motor control device according to any one of claims 9 to 11, wherein the motor control device is characterized by the above. The second control mode is a control mode that controls the drive current flowing through the winding so that the deviation between the command phase representing the target phase of the rotor and the rotation phase determined by the phase determining means becomes small. The motor control device according to any one of claims 9 to 11, wherein the motor control device is characterized by the above. The motor control device according to any one of claims 9 to 13 , wherein the value corresponding to the rotation speed of the rotor is a speed representing the target speed of the rotor. The motor control device has a speed determining means for determining the rotational speed of the rotor.
The motor control device according to any one of claims 9 to 13 , wherein the value corresponding to the rotation speed of the rotor is the rotation speed determined by the speed determination means. The motor control device has an induced voltage determining means for determining an induced voltage induced in the winding by the rotation of the rotor based on the drive current detected by the detecting means.
The aspect according to any one of claims 9 to 15 , wherein the phase determining means determines the rotational phase of the rotor based on the value of the induced voltage determined by the induced voltage determining means. Motor control device. The transport unit that transports the sheet and
The motor that drives the transport unit and
The motor control device according to any one of claims 1 to 16 .
Have,
The motor control device is a sheet transfer device characterized in that it controls the drive of a motor that drives the transfer unit. An image forming means for forming an image on a recording medium,
The motor that drives the load and
The motor control device according to any one of claims 1 to 16 , wherein the motor control device controls the motor that drives the load.
An image forming apparatus characterized by having.

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