JP2017046368A - Motor overload abnormal condition detecting device, motor drive control device, image forming device, and method of detecting motor overload abnormal condition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue the drive of a motor near a limit of an available condition, while detecting an abnormal condition so as not to break a motor or exceed a temperature standard value.SOLUTION: An encoder 35 detects the rotation speed of a motor M, and an instruction value computing portion 36 computes a torque instruction value according to the rotation speed. A movement average value calculating portion 41 of a motor overload abnormal condition detecting portion 40 obtains the torque instruction value about each section of a predetermined time period, and calculates a movement average value of the torque instruction value in a predetermined number of sections till the newest section. A determining portion 42 determines the presence/absence off an overload abnormal condition by comparing the movement average value with a threshold value. When it is determined that there is no overload abnormal condition, an instruction value switching portion 43 outputs a voltage instruction value corresponding to the inputted torque instruction value, and when it is determined that there is an overload abnormal condition, the instruction value switching portion 43 outputs the voltage instruction value by changing that to, for example, zero. The voltage instruction value is converted into a PWM instruction value by a PWM converting portion 37, thereby controlling a motor drive circuit 33 to drive the motor M.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a motor overload abnormality detection device, a motor drive control device, an image forming apparatus, and a motor overload abnormality detection method.

  Motors are frequently used as drive sources for various devices. The motor must be used with caution in raising the winding temperature. It is known that if the motor usage conditions are outside the range of the assumed usage conditions and an overload condition occurs, the winding temperature may rise and the motor may be damaged, or the temperature may exceed the safety standards. Yes.

In order to cope with this problem, an overload state of the motor is detected and the operation of the motor is stopped, or the duty of the motor drive voltage is reduced to reduce the substantial motor drive current.
For example, in Patent Document 1, when it is determined that the motor is in an overload state, the rotational speed of the motor is reduced to a predetermined speed. Is stopped.

However, in such a conventional method, when the motor overload detection is performed in order to suppress the rise in the winding temperature, the operation is performed when the drive current of the motor or the voltage instruction value to the motor exceeds a certain threshold value. Stopping or limiting the motor drive current. For this reason, there has been a problem that an abnormality is detected before the actual winding temperature of the motor becomes a state where the temperature standard cannot be satisfied.
In order to reduce downtime during which the user cannot use the device, it is desirable to continue operating the motor to the limit of the operable range. However, when the overload is detected, the motor is stopped immediately or the motor drive current is limited more than necessary, resulting in a situation where the downtime becomes longer.

  The present invention has been made to solve such problems, and continues to drive the motor to near the limit of usable conditions while detecting an abnormality so that the motor is not damaged or does not exceed the temperature standard value. The purpose is to reduce the downtime of the motor-using device.

In order to achieve the above object, the motor overload abnormality detection device according to the present invention detects a motor overload abnormality based on a motor drive instruction value calculated according to the rotation speed of the motor, and according to the detection result. A motor overload abnormality detection device that outputs a motor drive instruction value,
A moving average value for obtaining a motor drive instruction value calculated according to the rotation speed of the motor for each section of a predetermined time and calculating a moving average value of the motor drive instruction value in a predetermined number of sections including the latest section A calculating means, a determining means for comparing the moving average value calculated by the moving average value calculating means with a preset threshold value to determine the presence or absence of an overload abnormality, and the determining means determining that there is no overload abnormality If this is the case, the motor drive instruction value corresponding to the motor drive instruction value calculated according to the rotation speed of the motor is output. If the determination means determines that there is an overload abnormality, the motor drive instruction value to be output is output. And a command value switching means for switching to zero or a value lower than the calculated motor drive command value.

  According to the present invention, it is possible to continue driving the motor to near the limit of the usable condition while detecting an abnormality so that the motor is not damaged or does not exceed the temperature standard value, thereby shortening the downtime of the equipment using the motor. can do.

1 is an overall view illustrating a schematic configuration of an embodiment of an image forming apparatus including a motor drive control device according to the present invention and a motor driven by the motor drive control device. FIG. 2 is a perspective view illustrating an example of a transport roller and a driving unit thereof in a paper feed / transport mechanism 21 in the image forming apparatus illustrated in FIG. 1. It is a block diagram which shows the structure of one Embodiment of the motor overload abnormality detection apparatus and motor drive control apparatus by this invention. It is a block diagram which shows the structure of other embodiment of the motor overload abnormality detection apparatus and motor drive control apparatus by this invention. It is a diagram which shows transition of the winding temperature rise of a motor when a fixed torque instruction value is given. It is a diagram for demonstrating parameters, such as a threshold value used in this invention, and a torque average value. It is a diagram for demonstrating the operation example by the motor overload abnormality detection part 40 shown in FIG. It is a flowchart of the main routine of the process by the motor overload abnormality detection part 40 in FIG. 3 for implement | achieving the operation | movement shown in FIG. 9 is a flowchart of a subroutine of step S2 (overload determination process) in FIG. FIG. 6 is a diagram for explaining another example of operation by the motor overload abnormality detection unit 40 shown in FIG. 3. FIG. 11 is a flowchart of a main routine of processing by the motor overload abnormality detection unit 40 in FIG. 3 for realizing the operation shown in FIG. 10. 12 is a flowchart of a subroutine of step S2 ′ (overload determination process) in FIG. 9 is a flowchart of a main routine in which processing for notifying an overload state is added to the motor overload abnormality detection operation shown in FIG. 8. 12 is a flowchart of a main routine in which processing for notifying an overload state is added to the motor overload abnormality detection operation shown in FIG.

Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.
[Embodiment of Image Forming Apparatus]
FIG. 1 is an overall view showing a schematic configuration of an embodiment of an image forming apparatus provided with a motor driven by a motor drive control device according to the present invention.
This image forming apparatus is a digital multi-function peripheral that realizes a plurality of functions such as a color copying machine, a scanner device, and a color printer, and includes an image forming unit (printer unit) 1, a paper feeding unit 2, and an image reading unit (scanner unit). 3 and an automatic document feeder (abbreviated as “ADF”) 4.
A paper discharge tray 5 is provided on one side surface of the image forming unit 1, and a manual feed tray 6 for inserting a manual document is provided on the other side surface.

The image forming unit 1 includes an image forming unit 10 including four image forming units for forming a color image, an image writing unit 14, an intermediate transfer belt 15, a positioning roller pair 16, a secondary transfer roller 17, A conveyance belt 18 and a fixing device 19 are provided.
The image forming unit 10 is an intermediate in which four image forming units for forming toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (Bk) are intermediate transfer members. It is arranged along the moving direction of the transfer belt 15. Each of the image forming units includes a photosensitive drum 11, a charging roller 12 and a developing device 13 disposed around the photosensitive drum 11.
The image forming unit for each color is different only in the colors of toner stored in the developing device 13 from yellow, magenta, cyan, and black.

The paper feed unit 2 includes any of four stages of paper feed cassettes 20 for storing transfer papers (recording media, papers) of four types and directions, and transfer papers stored in the paper feed cassettes 20. A sheet feeding / conveying mechanism 21 that sequentially feeds these to the image forming unit 1 is provided.
The paper feeding / conveying mechanism 21 is provided with a number of paper feeding rollers and conveying rollers that are each driven to rotate by a motor.

The image forming apparatus includes a controller that performs sequence control of an image forming operation and the like, a power supply device that supplies power to each unit, and the like. The photosensitive drums 11, the driving rollers for the intermediate transfer belt 15, the positioning roller pair 16, the driving rollers for the conveying belt 18, the rollers in the fixing device 19, the feeding rollers and the conveying rollers of the sheet feeding / conveying mechanism 21, etc. Each motor for driving the motor and its motor drive control circuit are also provided.
An operation panel is provided at a position that is easy to see outside the image forming apparatus, and allows the user to input various function selections, operation instructions, etc., and display the status of the apparatus, for example, an overload abnormality or a forced motor stop described later. ing.

Here, the operation when the image forming apparatus functions as a copying machine will be briefly described.
When the user sets a document to be copied on the ADF 4 or opens the ADF 4 and places the document on the contact glass of the image reading unit 3, closes the ADF 4, and then presses the start button on the operation panel, the image is formed. The device starts a copying operation.

  When a document is set on the ADF 4, the ADF 4 conveys the document one by one through the document reading position of the image reading unit 3. Then, the image reading unit 3 scans the original while irradiating the original with light, and the image is read by the CCD line sensor for color reading by the reflected light from the original. When a document is placed on the contact glass, the image reading unit 3 scans the document while irradiating light, and similarly reads the image of the document.

The image data read by the CCD line sensor is subjected to image processing such as scanner γ correction, color conversion from RGB 3 colors to YMCBk 4 colors, image separation, gradation correction processing, and the like by the image processing unit of the image reading unit 3. It is sent to the image writing unit 14 of the forming unit 1.
The image writing unit 14 modulates the driving of the LD (laser diode) for each color according to the YMCBk4 color image data.

The image forming unit for each color in the image forming unit 10 has its outer peripheral surface uniformly charged by the charging roller 12 while each photoconductive drum 11 rotates counterclockwise in FIG. 1 and is irradiated from the LD of the image writing unit 14. The laser beam is exposed and scanned, and an electrostatic latent image is written.
The electrostatic latent images are visualized by the toners of the respective colors attached thereto by the developing units 13, and the toner images of the respective colors are formed on the outer peripheral surfaces of the respective photosensitive drums 11. The toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 15 in a primary transfer portion at a predetermined timing, thereby forming a full-color toner image.

In the meantime, the transfer sheet selected according to the size of the original is conveyed from one of the sheet feeding cassettes 20 of the sheet feeding unit 2 to the image forming unit 1 by the sheet feeding / conveying mechanism 21, and the transfer sheet The front end is stopped in a state where it reaches the positioning roller pair 16.
Then, in accordance with the timing when the full-color toner image on the intermediate transfer belt 15 reaches the secondary transfer portion facing the secondary transfer roller 17, the positioning roller pair 16 is activated to feed the transfer paper to the secondary transfer portion. Then, the full color toner image is collectively transferred onto the transfer paper.

The transfer sheet on which the full-color toner image is transferred is sent to the fixing device 19 by the transport belt 18, where the toner image is thermally fixed by the fixing roller and the pressure roller, and then discharged onto the discharge tray 5. .
When forming a black and white image, the image forming unit 1 operates only the black image forming unit of the image forming unit 10 to form a black and white image.

When this image forming apparatus functions as a printer, the image forming apparatus 1 receives print data transmitted from a host device such as a personal computer, and the image forming unit 1 performs the same as described above based on the print data. Create a color or black and white image.
When this image forming apparatus is operated as a scanner, only the image reading unit 3 and the ADF 4 are operated to read an image of an original, store the image data in an internal memory, and an external personal computer as necessary. To the host device.

FIG. 2 is a perspective view showing an example of a transport roller and its drive unit in the paper feed / transport mechanism 21 in the image forming apparatus shown in FIG.
The conveying roller 25 shown in FIG. 2 is rotated in the direction indicated by the arrow A when the rotational force of the motor 22 is transmitted by the meshing of the small gear 23 and the spur gear 24. A driven roller 26 is rotatably provided so as to be parallel to the transport roller 25 and partly in contact with each other. The transfer paper P, which is a recording medium, is sandwiched at the nip portion between the transport roller 25 and the driven roller 26 and transported in the direction indicated by the arrow B.
The sheet feeding / conveying mechanism 21 is provided with a large number of such conveying rollers 25, and the motors 22 that drive the respective conveying rollers 25 are driven and controlled by a motor drive control device to be described later according to the present invention.

The image forming apparatus to which the present invention is applied is not limited to the color multifunction peripheral shown in the above embodiment, and may be a single-function image forming apparatus such as a copying machine, a printer, or a facsimile machine, or a monochrome image forming apparatus. In the case of color, the color may not be full color, and is not limited to the tandem method or the intermediate transfer method.
Further, the motor overload abnormality detection device and motor drive control device according to the present invention described below are applicable not only to an image forming apparatus but also to various devices including members that are rotationally driven by a motor.

[Configuration example of motor overload abnormality detection device and motor drive control device]
FIG. 3 is a block diagram showing the configuration of an embodiment of the motor overload abnormality detection device and motor drive control device according to the present invention.
This motor drive control device includes an encoder 35 which is a speed detection means for detecting the rotation speed of the motor M, a motor control unit 32 and a motor drive circuit 33 which is controlled by the motor control unit 32 and drives the motor M. ing. The motor control unit 32 and the motor drive circuit 33 constitute a motor drive control unit 31.

The motor control unit 32 of this embodiment is provided with an instruction value calculation unit 36, a PWM conversion unit 37, and a motor overload abnormality detection unit 40. The motor overload abnormality detection unit 40 includes a moving average value calculation unit 41, a determination. A unit 42 and an instruction value switching unit 43. This motor overload abnormality detection part 40 is one Embodiment of the motor overload abnormality detection apparatus by this invention.
The motor M is, for example, a motor 22 that rotationally drives the transport roller 25 shown in FIG.

The main control unit 30 starts and stops (START / STOP) the motor M by the motor drive control unit 31 and controls the entire image forming apparatus including the motor drive control unit 31 and the motor M (controller). ).
When a start signal (motor START signal) is sent from the main control unit 30 to the motor control unit 32 of the motor drive control unit 31, the motor control unit 32 starts to start the motor M.
After the motor M is started, the current rotation speed of the motor M is detected by the encoder 35 and fed back to the motor control unit 32.

The instruction value calculation unit 36 compares the feedback rotation speed with the target speed, and increases the torque instruction value when the instruction speed is slower than the target speed, and decreases the torque instruction value when the instruction speed is faster than the target speed. Calculate and output the value. The torque instruction value is a motor drive instruction value and corresponds to a voltage instruction value to the motor M. The target speed is stored in the motor control unit 32 or is instructed from the main control unit 30.
In the case of a general motor drive control circuit in which the motor overload abnormality detection unit is not provided in the motor control unit, the torque instruction value (or voltage instruction value) output from the instruction value calculation unit 36 is directly input to the PWM conversion unit 37. And converted into a PWM instruction value.

Then, the windings of the motor M are controlled by controlling the ON / OFF of six drivers (illustrated FETs) S1 to S6 of the motor drive circuit 33 in the motor drive control unit 31 with the PWM instruction values. A three-phase (U, V, W phase) driving voltage is applied to the stator coil. As a result, a drive current flows sequentially for each of the two phases of the stator coil, and the motor M rotates.
The encoder 35 detects the rotational speed of the motor M and feeds it back to the motor control unit 32. In this way, the motor drive voltage changes according to the actual rotational speed of the motor M, feedback control is performed, and the motor M is rotated at a constant target speed. Each driver of the motor drive circuit 33 may be a bipolar transistor.

  This motor drive circuit 33 is also called an inverter circuit, and two sets of drivers S1 and S2, S3 and S4, and S5 and S6, which are connected in series, are connected in parallel between the DC power source VDD and the ground. Yes. The connection points of the two drivers are connected to the open ends of the three stator coils that are star-connected to the motor M, respectively. R1 is a protective resistor inserted between the motor drive circuit 33 and the ground.

  In this way, in the motor drive control device that detects the rotational speed of the motor M by the encoder 35 that is speed detection means and controls the rotational speed to be a constant target speed, the load becomes large and the rotational speed becomes slow. If this happens, increase the motor drive instruction value. As a result, the drive current to be supplied to the motor M is increased. However, if the motor drive instruction value (torque instruction value or voltage instruction value) is excessively increased, the winding temperature of the motor M rises and the motor emits smoke or breaks. There is a case to do. In order to prevent this, it is necessary to provide means for detecting an overload condition of the motor, limiting the motor drive instruction value, and limiting an increase in drive current.

In the motor drive control device of this embodiment, a motor overload abnormality detection unit 40 is provided in the motor control unit 32 for this purpose.
The motor overload abnormality detection unit 40 calculates the motor winding temperature for a certain period of time of a motor drive instruction value (torque instruction value or voltage instruction value) calculated according to the detected value of the rotational speed of the motor M. Based on the moving average value of the calculated values, the presence or absence of motor overload abnormality is determined. And when it determines with motor overload abnormality, a motor drive is stopped or drive current is reduced only in the following area. Accordingly, the motor is prevented from being stopped more than necessary or the intermittent time is prevented from being extended, and the motor can be driven to near the limit of the usable condition.

Therefore, the function of the motor overload abnormality detection unit 40 will be described in more detail.
Based on the rotational speed of the motor M, the torque instruction value calculated by the instruction value calculation unit 36 is input to the motor overload abnormality detection unit 40 to determine overload, and the voltage instruction value is switched according to the determination result. Output to the PWM converter 37. As described above, the torque instruction value and the voltage instruction value are both motor drive instruction values and correspond to each other. In the following description, the motor drive instruction value input to the motor overload abnormality detection unit 40 is described as a torque instruction value, and the motor drive instruction value output from the motor overload abnormality detection unit 40 is distinguished as a voltage instruction value.

The motor overload abnormality detection unit 40 is provided with a moving average value calculation unit 41, a determination unit 42, and an instruction value switching unit 43. The moving average value calculation unit 41 is a moving average value calculation unit, the determination unit 42 is a determination unit, and the instruction value switching unit 43 is an instruction value switching unit.
The moving average value calculation unit 41 acquires the torque instruction value, which is the calculation result of the instruction value calculation unit 36, for each interval of a fixed time, and the moving average value of the torque instruction value in a preset number of intervals up to the latest interval. Is calculated. Details thereof will be described later.
The determination unit 42 determines whether or not there is an overload abnormality by comparing the moving average value of the torque instruction value calculated by the moving average value calculation unit 41 with a preset threshold value. The threshold value will also be described later.

When the determination unit 42 determines that there is no overload abnormality, the instruction value switching unit 43 outputs the voltage instruction value corresponding to the torque instruction value input from the instruction value calculation unit 36 as it is, and determines that there is an overload abnormality. In this case, the voltage instruction value is switched to, for example, zero (0) and output. However, without switching to zero, the voltage command value corresponding to the torque command value input from the command value calculation unit 36 is reduced to a predetermined ratio, for example, 1/2, or a constant value lower than the voltage command value. It may be switched to a smaller value.
Further, when the determination unit 42 determines that there is an abnormality, the main control unit 30 can be notified that an overload abnormality has occurred.

The voltage command value output from the command value switching unit 43 of the motor overload abnormality detection unit 40 is input to the PWM conversion unit 37 and converted into a PWM command value. The motor M is driven by controlling ON / OFF of the six drivers S1 to S6 of the motor drive circuit 33 according to the PWM instruction value.
In this embodiment, the main control unit 30 and the motor control unit 32 are configured separately, and each includes a microcomputer that includes a CPU, a ROM, a RAM, and the like. However, you may comprise the main control part 30 and the motor control part 32 as an integrated control part which operate | moves with the same micro computer (CPU).
The PWM conversion unit 37 is means for controlling the motor drive circuit 33 in accordance with the voltage instruction value output from the instruction value switching unit 43 of the motor overload abnormality detection unit 40. This means is not limited to the PWM conversion unit, and may be a PFM conversion unit or other conversion circuit.

FIG. 4 is a block diagram showing the configuration of another embodiment of the motor overload abnormality detection device and motor drive control device according to the present invention.
The motor drive control device shown in FIG. 4 is different from the motor drive control device shown in FIG. 3 in that it includes motor drive current detection means 38 for detecting the drive current of the motor M. The detected value is also input to the motor overload abnormality detector 40 '. In this embodiment, the protection resistor R1 in FIG. 3 is also used as the motor drive current detection means 38. A voltage generated in proportion to the value of the current flowing through the resistor R1 is input to the motor overload abnormality detecting unit 40 ′ of the motor control unit 32 as a detected value of the motor driving current (motor driving current value).
This motor overload abnormality detection unit 40 'is the motor overload abnormality detection device in this embodiment.

Then, the moving average value calculation unit 41 ′ of the motor overload abnormality detection unit 40 ′ performs A / D conversion on the motor drive current value detected by the motor drive current detection unit 38 and takes it in every predetermined section (time). Save with. Then, the moving average value of the motor drive current value in the preset number of sections up to the latest section is calculated.
Further, the determination unit 42 ′ determines the presence or absence of an overload abnormality by comparing the moving average value of the motor drive current calculated by the moving average value calculation unit 41 ′ with a preset threshold value.

When the determination unit 42 'determines that there is no overload abnormality, the instruction value switching unit 43 outputs the voltage instruction value corresponding to the torque instruction value input from the instruction value calculation unit 36 as it is, and determines that there is an abnormality. In this case, the voltage instruction value is switched to, for example, zero (0) and output. Other switching examples are the same as those described for the instruction value switching unit 43 of the motor overload abnormality detection unit 40 in FIG. The same applies to other modified examples.
The motor drive control unit 31 and the motor control unit 32 in FIG. 4 are somewhat different in configuration from the motor drive control unit 31 and the motor control unit 32 shown in FIG. The same reference numerals are given.

[Operation example of motor overload error detector]
Hereinafter, an operation example of the motor overload abnormality detection unit 40 shown in FIG. 3 will be described with reference to FIGS.
FIG. 5 is a diagram showing a transition of the winding temperature rise of the motor when a constant torque instruction value is given. The horizontal axis in FIG. 5 represents the elapsed time from the start of the motor, and the vertical axis represents the torque instruction value (voltage instruction value) and the winding temperature.

In this example, a constant torque instruction value A indicated by a bold line is continuously given to the PWM conversion unit 37 shown in FIG. The temperature rise of the winding at this time becomes a rise curve as shown by a curve, and finally becomes constant at X ° C.
This is also evident from the general temperature rise equation 1.
[Formula 1]
Temperature rise = heat transport amount (heat flow rate) [W] · R · {1-exp {-t / (RC)}}
(R: Thermal resistance (° C / W) C: Heat capacity (J / ° C) t: Time (S))

The temperature rise characteristic expressed by the above equation 1 will be briefly described.
When the winding temperature of the motor is low, the temperature difference from the ambient temperature is small, so the heat flow released to the surroundings is small, so the winding temperature rises steadily. However, as the winding temperature rises, the temperature difference from the ambient temperature increases and the heat flow released to the surroundings increases, so the amount of heat finally given to the winding and the amount of heat released to the surroundings are balanced. By the way, the winding temperature becomes constant.

FIG. 6 is a diagram for explaining parameters such as a threshold value and a torque average value used in the present invention. The abscissa indicates the elapsed time from the start of the motor, and the ordinate indicates the torque average value (voltage average value), which is the average value for each section of the torque instruction value (voltage instruction value), and the winding temperature.
A in FIG. 6 is a torque average value at the maximum load under normal use conditions. When this torque average value A continues, the temperature at which the winding temperature of the motor finally becomes constant based on Equation 1 is defined as Z ° C. On the other hand, the temperature that must not be exceeded is defined as W ° C. according to the standard value of the safety standard or the specification of the winding.

Here, the threshold values A and B of the torque average value, the temperature W ° C., and the average value ΔU of the torque instruction value which are the premise of the present invention will be described.
First, the threshold value B is set in a range that does not reach W ° C. from Z ° C. within the time ΔT. This state is a value that exceeds the torque instruction value A (threshold A) at the maximum load under normal use conditions, and an average overload threshold B indicates an overload state.
In each ΔT section, the torque instruction value in that section is accumulated and divided by the cumulative number, thereby obtaining an average torque instruction value ΔU (ΔU1, ΔU2, ΔU3,... ., ΔUm, ΔUm + 1,...

The reason for taking the section average value of ΔT without taking the instantaneous value of the torque instruction value in each section data is that the torque instruction value corresponding to the voltage instruction value to the motor has a large instantaneous variation, and the instantaneous value indicates the state of the load. This is because there is a possibility that it cannot be determined correctly.
In addition, when the condition where the average torque value ΔU which is the average value of the torque instruction values in the section continues to be the threshold value B from the state where the winding temperature is Z ° C., the time until the temperature becomes W ° C. is set in advance. Derived.
When the heat flow rate, the thermal resistance, and the heat capacity are known, the time t can be obtained from the above equation 1. If these parameters are not known, the time t is obtained by temperature measurement.

FIG. 7 is a diagram for explaining an operation example by the motor overload abnormality detection unit 40 shown in FIG. 3, and shows the transition of the torque average value (voltage average value) ΔU and the winding temperature.
In the motor overload abnormality detection unit 40 of the motor control unit 32 shown in FIG. 3, the following calculation and determination are performed.
First, the motor overload abnormality detection unit 40 acquires the torque average value (voltage average value) ΔU described in FIG. The torque average value ΔU is acquired by the moving average value calculation unit 41.

  Based on the rotation speed of the motor M detected by the encoder 35, which is the speed detection means shown in FIG. 3, the instruction value calculation unit 36 calculates a torque instruction value for the motor M from when the motor M is started up. The load abnormality detection unit 40 is input. The torque instruction value is received by the moving average value calculation unit 41, and a torque average value ΔU, which is an average value of the torque instruction values in the section, is calculated every time ΔT, and is sequentially stored in the storage buffer for each section. Store it.

Then, the moving average value of the average value ΔU stored in the storage buffer is calculated. For example, when the acquisition data of the torque average value in the latest section is ΔUm, a moving average for a predetermined number of sections up to the latest section is obtained. Here, an example in which a moving average value for four sections is obtained is shown, and the moving average value Um is calculated by (ΔUm + ΔUm−1 + ΔUm−2 + Um−3) / 4.
For each calculation, the determination unit 42 compares the moving average value Um + α with the threshold B to determine whether there is an abnormality due to overload.

  When the determination unit 42 determines that the moving average value Um + α does not exceed the threshold value B (no overload abnormality), the voltage corresponding to the torque instruction value input from the instruction value calculation unit 36 by the instruction value switching unit 43 The indicated value is output as it is. When the determination unit 42 determines that the moving average value Um + α exceeds the threshold B (there is an overload abnormality), the voltage instruction value is switched to 0 and output. In other words, the motor M is stopped in the next ΔT time interval as an intermittent interval.

Then, the moving average value (Um + 1, Um + 2, Um + 3,...) Of the torque average value for each of the four sections is calculated continuously including ΔT of the stopped period, and the moving average value Um + α reaches the threshold value B. If it falls below, the voltage instruction value is output again to drive the motor M.
In the case of FIG. 7, the moving average values Um + 1, Um + 4, and Um + 6 exceed the threshold value B, and the motor is stopped in the next section.

By doing so, the winding temperature transitions in a sawtooth waveform shown by a solid curve in FIG. 7, and even when the moving average value exceeds the threshold B, the winding temperature does not exceed the standard value and specification. The driving of the motor can be continued. A dotted curve indicates an increase curve of the winding temperature when the torque average value maintains the threshold value B.
Detailed control processing will be described with reference to the flowcharts of FIGS.

[Description of Flowchart for Realizing Operation of FIG. 7]
8 and 9 are flowcharts of processing by the motor overload abnormality detecting unit 40 in FIG. 3 for realizing the operation shown in FIG. FIG. 8 is a main routine, and FIG. 9 is a subroutine of step S2 (overload determination process) in FIG.
In the processing shown in this flowchart, the microcomputer provided in the motor control unit 32 shown in FIG. 3 functions as the moving average value calculation unit 41, the determination unit 42, and the instruction value switching unit 43 of the motor overload abnormality detection unit 40. It is a process by a program for making it happen. In the following description, the microcomputer is abbreviated as “CPU”.

When the power of the image forming apparatus is turned on, the CPU starts the processing of the main routine of FIG. 8, and first determines in step S1 whether the motor is being activated. This is because the motor start (START) signal is input to the motor control unit 32 from the main control unit 30 shown in FIG. 3 to start the motor M, or the motor stop (STOP) signal is input to stop the motor M. Judge whether to do.
Since the motor activation process by the motor control unit 32 is the same as the conventional one, the description thereof is omitted. When the CPU determines that the motor is being started in step S1, an overload determination process shown in FIG. 9 is executed in step S2.

In this overload determination process, the CPU first determines whether or not Ta = Tx (time ΔT has elapsed) in step S201. Ta is a count value of a time measurement counter for measuring the time ΔT of each section shown in FIG. 7, and Tx is a count value (Tx = ΔT) corresponding to the time ΔT of one section.
Of course, since Ta = Tx is not satisfied at the beginning, the CPU determines NO and proceeds to step S202 to set the current torque instruction to the accumulated value Ua (initially 0) of the torque instruction value input from the instruction value calculator 36. The values are added to obtain a new accumulated value Ua. Thereafter, in step S203, the time measurement counter is incremented, the count value Ta is incremented by 1, and the process returns to step S201. Until the CPU determines Ta = Tx in step S201, the processing of S202 and S203 is repeated and the torque instruction value for each section is cumulatively added.

When the CPU determines that Ta = Tx in step S201, since the time ΔT of one section has elapsed, the process proceeds to step S204, and ΔU = Ua / Tx is calculated. This calculation is to obtain the torque average value ΔU in this section by dividing the cumulative value Ua of the torque instruction value by the count value Tx corresponding to the time ΔT in this section.
In step S205, the CPU stores the torque average value ΔU obtained in step S204 in the storage buffer ΔUm. In step S206, the CPU counts up the storage buffer counter and sets the count value m to m + 1.

Next, in step S207, the CPU calculates a moving average value of the average value ΔU of the torque instruction values stored in the storage buffer for a predetermined section including the current section. The number of sections is determined in advance at the time of designing the apparatus and set in the memory.
For example, when the current torque average value stored in the latest storage buffer is set to ΔUm and the moving average values for the four sections so far are obtained, as shown in parentheses in step S207,
(ΔUm + ΔUm−1 + ΔUm−2 + ΔUm−3) / 4
The moving average value Um of the torque average value ΔU is calculated by the above calculation.

Note that the moving average value in the initial stage immediately after the start of the motor is obtained by the following calculation in the case of a four-section moving average.
In the first one section, the other three sections are set to 0 (ΔUm + 0 + 0 + 0) / 4, and in the second section, the second and third previous sections are set to 0 and (ΔUm + ΔUm−1 + 0 + 0) / 4 is calculated. In the third section, the calculation of (ΔUm + ΔUm−1 + ΔUm−2 + 0) / 4 is performed with the third previous section as 0. As described above, the torque average value is calculated as “0” in the section before starting the motor.
This is the processing corresponding to the function or procedure of the moving average value calculation unit 41 in FIG.

Thereafter, in step S208, the CPU determines whether or not the moving average value Um calculated this time has exceeded the threshold value B shown in FIG. As a result, if the CPU determines that the moving average value Um has exceeded the threshold B (there is an overload abnormality), an intermittent stop flag is set in step S209. If the CPU determines that the moving average value Um does not exceed the threshold B (no overload abnormality), the intermittent stop flag is cleared in step S210.
The processing in steps S208 to S210 is processing corresponding to the function or procedure of the determination unit 42 shown in FIG.

In either case, the count value Ta of the time measurement counter and the cumulative value Ua of the torque instruction value are cleared to 0 in the next step S211, and the process returns to the main routine of FIG.
Note that the number of sections (time) in which the moving average of the torque average value ΔU is taken is such that the winding temperature of the motor M does not reach W ° C. from Z ° C. shown in FIG. Set the range.
The number of sections for calculating the moving average value is set in advance, but may be changed thereafter. For example, after use of the image forming apparatus, the service person may be able to change it according to installation conditions, usage conditions, and the like.

  When the CPU returns to the process of the flowchart of FIG. 8, it is determined in step S3 whether or not the intermittent stop flag is set. As a result, if the intermittent stop flag is set, the voltage instruction value to the motor is set to 0 in step S4 regardless of the torque instruction value from the instruction value calculator 36. If the intermittent stop flag is not set, a value corresponding to the torque instruction value from the instruction value calculation unit 36 is set as a voltage instruction value to the motor in step S5. The processing in steps S3 to S5 is processing corresponding to the function or procedure of the instruction value switching unit 43 shown in FIG.

If the CPU determines in step S1 that the motor is not being started (stopped), the intermittent stop flag is cleared in step S6. Further, the count value Ta of the time measurement counter and the accumulated value Ua of the torque instruction value are cleared to 0 in step S7, and all the buffers ΔUm and the like are cleared to 0 in step S8.
After performing the processes of steps S4, S5, and S8, the CPU returns to step S1 and repeats the above-described processes.

In this way, the voltage command value set by the CPU is output from the command value switching unit 43 of the motor overload abnormality detection unit 40 to the PWM conversion unit 37, where it is converted into a PWM command value to control the motor drive circuit 33. The motor M is driven.
Accordingly, the operation described with reference to FIG. 7 can be realized, and the driving of the motor can be continued to near the limit of the usable condition within a range not exceeding the standard value and specification of the temperature.

[Other operation examples of motor overload abnormality detection unit]
Another operation example by the motor overload abnormality detection unit shown in FIG. 3 will be described with reference to FIGS.
In the above-described operation example, when the moving average value Um + α of the torque average value of the predetermined number of sections exceeds the threshold value B, the voltage instruction value to the motor in the next section is set to 0 to be an intermittent stop section. However, depending on the state of use of the motor that is driven and controlled by this motor drive control device, there may be a case where the intermittent stop cannot be performed immediately. For example, in the case of a motor that rotates a conveyance roller of an image forming apparatus, intermittent stopping cannot be performed when the conveyance roller is actually conveying a transfer sheet.

In such a case, until the timing at which the motor M may be stopped (for example, when the motor M rotationally drives the transport roller shown in FIG. 2, after the transport roller is not transporting the transfer paper). The drive of the motor M is continued. Thereafter, the voltage instruction value to the motor M is set to 0, and intermittently stopped until the temperature does not exceed the standard value. By doing so, it becomes possible to continue the operation near the limit without abnormally stopping the device using the motor M while satisfying the standard value of the winding temperature and the product specification. The downtime of the forming apparatus can be shortened.
When the motor M drives a member related to the transfer paper (also referred to as paper) in the image forming apparatus, the timing at which the motor M can be stopped is after the paper is carried out of the machine or temporarily stopped in the machine. It is good after transporting it to the retreat position where it is possible.

FIG. 10 is a diagram similar to FIG. 7 for explaining the operation example.
In the case of the operation example described with reference to FIG. 7, when the moving average value Um for four sections of the torque average value, which is the average value of the torque instruction values for each section of time ΔT, exceeds the threshold value B, the next section is always the voltage. The indicated value was set to 0 and the motor M was stopped intermittently.
If the control is performed in the same manner, the moving average value is Um + 1 and exceeds the threshold value B in FIG. 10, so that the voltage indicated value is set to 0 and the motor M is intermittently stopped in the next hatched section.
However, since the section is the “stop prohibition timing”, the motor M is continuously driven with the voltage instruction value corresponding to the torque instruction value input from the instruction value calculation unit 36 in FIG.

Thereafter, the voltage instruction value to the motor M is set to 0 in the section where the “stoppable timing” is reached. In the example of FIG. 10, the moving average value has exceeded the threshold B three times (Um + 1, Um + 2, Um + 3) before reaching the “stoppable timing”, but the voltage instruction value is set to 0 because it is “stop prohibition timing”. could not. Therefore, the voltage instruction value to the motor is set to 0 over the number of sections (three sections). Thereafter, the moving average value Um + 6 does not exceed the threshold value B, the voltage instruction value is returned to the normal value corresponding to the torque instruction value input from the instruction value calculation unit 36, and the motor M is driven.
As a result, the winding temperature of the motor M changes in a sawtooth waveform shown by a solid line in FIG. 10, and the motor is driven within the range where the winding temperature does not exceed the standard value and specifications even when the moving average value exceeds the threshold value B. Can be continued. A dotted curve indicates an increase curve of the winding temperature when the torque average value maintains the threshold value B.

[Description of Flowchart for Realizing Operation of FIG. 10]
FIG. 11 is a flowchart of a main routine of processing by the motor overload abnormality detection unit 40 in FIG. 3 for realizing the operation shown in FIG. 10, and FIG. 12 shows step S2 ′ (overload determination processing in FIG. 11). ) Is a flowchart of the subroutine.
In the processing shown in this flowchart, the microcomputer (CPU) included in the motor control unit 32 shown in FIG. 3 is also replaced with the moving average value calculation unit 41, the determination unit 42, and the instruction value switching unit of the motor overload abnormality detection unit 40. This is processing by a program for causing the program to function as 43.
In FIGS. 11 and 12, steps that perform the same determinations or processes as those in FIGS. 8 and 9 are denoted by the same step symbols, and description thereof will be simplified or omitted.

When the CPU starts the process of the flowchart shown in FIG. 11 and determines that the motor is being started in step S1, an overload determination process shown in the subroutine of FIG. 12 is performed in step S2 ′.
The determinations and processes in steps S201 to S208 are the same as those in the subroutine of FIG. In FIG. 9, when the CPU determines that the current moving average value Um exceeds the threshold value B in the determination in step S208, the intermittent stop flag is set in the next step S209.

However, in the case of FIG. 12, first, in step S221, the CPU counts up an intermittent stop cancellation number counter that counts the number Nc of sections in which intermittent stop is canceled, and increments Nc by one. Since Nc is 0 at first, Nc = 1 is set.
Thereafter, in step S222, the CPU determines whether or not it is a motor stoppable timing. If it is a stoppable timing, the CPU proceeds to step S209 to set an intermittent stop flag.
In the next step S211, the count value Ta of the time measurement counter and the accumulated value Ua of the torque instruction value are cleared to 0, and the process returns to the main routine of FIG.

If the CPU determines in step S222 that it is not the motor stoppable timing (motor stop prohibition timing), the process proceeds to step S223. Here, it is determined whether or not the count number Nc of the intermittent stop cancellation number counter exceeds a preset maximum value Nmax (Nc> Nmax). As a result, if it is determined that Nc> Nmax, the motor forced stop flag is set in step S224, and the process returns to the main routine of FIG.
If the CPU determines in step S223 that Nc> Nmax is not satisfied (Nc ≦ Nmax), the count value Ta of the time measurement counter and the cumulative value Ua of the torque instruction value are cleared to 0 in step S211. Return to routine.

When returning to the main routine, the CPU determines whether or not a motor forced stop flag is set in step S9. As a result, if the motor forced stop flag is set, the motor is forcibly stopped in step S10, the motor forced stop is notified to the main control unit 30 in FIG. 3 (abnormal notification), and the processing of this flowchart is terminated. .
When the main control unit 30 is notified of the motor forced stop, the main control unit 30 displays characters or marks of “motor forced stop” on the operation panel, generates an alarm sound, and notifies the user of it. I can inform you.

  Even if it is a system stop prohibition timing systematically, if the motor is not stopped, a situation exceeding the temperature standard or the component specification of the winding may occur. It is to do. The maximum value Nmax of the count number Nc (number of sections in which intermittent stop is canceled) of the intermittent stop cancellation number counter used in step S223 in FIG. 12 is a count in a range where the winding temperature does not exceed W ° C. shown in FIG. The value is obtained by conducting a temperature test in advance.

If the CPU determines in step S9 that the motor forced stop flag is not set, it is next determined in step S3 whether or not the intermittent stop flag is set. If it is set, the voltage instruction value is set to 0 in step S4, the intermittent stop cancellation number counter is counted down in step S11, and the count number Nc is set to Nc-1.
Thereafter, the CPU determines whether or not Nc = 0 in step S12, and if Nc = 0, clears the intermittent stop flag in step S13, and then returns to step S1 if Nc = 0 is not satisfied in step S12. The above process is repeated.

If the CPU determines that the intermittent stop flag is not set in step S3, a value corresponding to the torque instruction value from the instruction value calculator 36 is set as a voltage instruction value to the motor in step S5. And it returns to step S1 and repeats the process mentioned above.
If the CPU determines that the motor is not being started in step S1, the intermittent stop cancellation number counter is cleared (Nc = 0) in step S14, and thereafter, each clear process in steps S6 to S8 is performed as in FIG. After that, the process returns to step S1.
By doing this, the motor voltage instruction value is set to 0 within the motor stoppable timing range for the duration of the number of sections in which the count number Nc of the intermittent stop cancellation number counter is counted up in step S221 in FIG. It can be stopped intermittently.

  Also in this operation example, when the intermittent stop flag is set, the voltage command value corresponding to the torque command value input from the command value calculation unit 36 of FIG. For example, a value reduced by a predetermined ratio such as ½ may be set. Alternatively, the voltage instruction value to be output may be switched by setting a constant small value lower than the voltage instruction value corresponding to the input torque instruction value. In this case, the flag is better referred to as an “indicated value lowering flag” than an “intermittent stop flag”.

[Explanation of the flowchart with added overload status notification function]
Next, an operation example in which processing for notifying the main control unit 30 of an overload state is added to each operation example described above with reference to FIGS. 13 and 14.
FIG. 13 is a flowchart of a main routine in which processing for notifying an overload state is added to the motor overload abnormality detection operation shown in FIG. 8, and is shown by shading after step S4 in FIG. Only steps S15 and S16 are added.

In this operation example, when the intermittent stop flag is set in step S3, and the CPU sets the voltage instruction value to 0 in step S4, in the next step S15, it is determined whether or not the operation is the first intermittent operation after the motor is started. to decide. As a result, if it is determined that this is the first intermittent operation after the motor is started, an overload state is notified in step S16 to the main control unit 30 in FIG. 3 (abnormal notification) and the process returns to step S1.
As a result, the main control unit 30 displays characters or marks such as “overload state” or “motor intermittent operation” on the operation panel or generates a warning sound to notify the user of this. it can.
If the CPU determines in step S15 that it is not the first intermittent operation after the motor is started, the process directly returns to step S1.

  FIG. 14 is a flowchart of a main routine in which processing for notifying an overload state is added to the motor overload abnormality detection operation shown in FIG. 11, and a shaded area is inserted between steps S4 and S11 in FIG. Only steps S15 and S16 described above are added. The determination in step S15 and the process in step S16 are the same as steps S15 and S16 in FIG.

  When an overload state is detected, it is considered that the system (image forming apparatus in this embodiment) in which the motor is mounted needs to be maintained. Therefore, when an overload condition is detected and the motor starts an intermittent operation, the user or service person can repair the motor while the motor is still in an intermittent operation. It becomes possible to make preparations. As a result, the downtime can be further reduced.

[Operation of Motor Overload Abnormality Detection Unit in FIG. 4]
The operation of the motor overload abnormality detection unit 40 'in the motor drive control device of another embodiment shown in FIG. 4 is also the same as that of the motor overload abnormality detection unit 40 in the motor drive control device of the embodiment shown in FIG. It is almost the same as the operation.
The difference from the operation of the above-described embodiment is that, as described in the explanation of FIG. 4, the motor drive current detection means 38 for detecting the drive current of the motor M is provided, and the detected value of the motor drive current is set to the motor overload. This is a point that is inputted to the load abnormality detection unit 40 '.

Then, the moving average value calculation unit 41 ′ of the motor overload abnormality detection unit 40 ′ performs A / D conversion on the motor drive current value detected by the motor drive current detection unit 38 and continuously takes it in a short cycle, An average value for each section (predetermined time) is calculated and stored. Then, the moving average value of the motor drive current values in the preset number of sections up to the latest section is calculated.
The determination unit 42 ′ determines the presence or absence of an overload abnormality by comparing the moving average value of the motor driving current calculated by the moving average value calculation unit 41 ′ with a preset threshold value.

  When the determination unit 42 ′ determines that there is no overload abnormality, the instruction value switching unit 43 outputs the voltage instruction value corresponding to the torque instruction value input from the instruction value calculation unit 36 as it is. When the determination unit 42 'determines that there is an overload abnormality, the command value switching unit 43 switches the voltage command value to, for example, zero (0) or a value considerably lower than the voltage command value corresponding to the input torque command value. Output.

  Therefore, when the operation of this embodiment is described, the “torque instruction value (voltage instruction value)” in FIG. 5 is set to “motor drive current value”, and the “torque average value (voltage) in FIGS. "Average value)" is defined as "motor drive current average value". Therefore, ΔU in FIG. 7 and FIG. 10 is the “motor drive current average value” for each section, and Um is the motor drive current average value in a predetermined number of sections (four sections in the embodiment) including the latest section. It is a moving average value.

The flowchart of the program for causing the microcomputer (CPU) of the motor control unit 32 in FIG. 4 to function as each unit of the motor overload abnormality detection unit 40 ′ is also the flowcharts of FIG. 8 and FIG. 9, or FIG. 11 and FIG. It is the same. Further, instead of FIG. 8, the flowcharts of FIG. 13 and FIG. 14 may be used instead of FIG.
However, in these figures, ΔU and Um are as described above. In FIG. 9 and FIG. 12, Ua in step S202 is the cumulative addition value of the motor drive current value in the interval of time ΔT, and “current torque instruction value” is “current motor drive current value”. In addition, the threshold value B to be compared with the current moving average value of the motor driving current in step S208 is the average value of the motor driving current and the threshold value of the moving average value, and within the time of ΔT shown in FIGS. The range is set so as not to reach W ° C from Z ° C.

[Motor overload error detection method]
According to the motor overload abnormality detection method of the present invention, a motor overload abnormality is detected based on a motor drive instruction value or an actual motor drive current value calculated according to the rotation speed of the motor, and the detection result is determined according to the detection result. This is a method of outputting a motor drive instruction value.
The embodiment includes a moving average value calculation procedure, a determination procedure, and an instruction value switching procedure executed by each unit of the motor overload abnormality detection unit 40 or 40 ′ described above. Each of the procedures is executed by the microcomputer (CPU) of the motor control unit 31 as described in the flowcharts described above.
When detecting an overload abnormality of the motor based on the motor drive current value, the operation procedure by each unit of the motor overload abnormality detection unit 40 ′ in the motor drive control device shown in FIG. Some changes are made as described above.

[Supplementary explanation]
As mentioned above, although embodiment of this invention was described, the specific structure of each part of the embodiment, the content of a process, etc. are not restricted to what was described there.
Further, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention is not limited in any way except for having the technical features described in the claims.
Furthermore, the configuration examples, operation examples, modification examples, and the like of the embodiments described above may be changed or added as appropriate, or some of them may be deleted, and any combination may be implemented as long as they do not contradict each other. is there.

1: Image forming unit 2: Paper feeding unit 3: Image reading unit (scanner unit)
4: Automatic document feeder (ADF) 5: Paper discharge tray 6: Manual feed tray 10: Image forming unit 11: Photoconductor drum 12: Charging roller 13: Developer
14: Image writing unit 15: Intermediate transfer belt 16: Pair of positioning rollers
17: Secondary transfer roller 18: Conveying belt 19: Fixing device 20: Paper feeding cassette 21: Paper feeding / conveying mechanism 22: Motor 23: Small gear
24: Spur gear 25: Conveying roller 26: Driven roller
30: Main control unit 31: Motor drive control unit 32: Motor control unit 33: Motor drive circuit 35: Encoder (speed detection means) 36: Instruction value calculation unit 37: PWM conversion unit 38: Motor drive current detection means 40, 40 ': Motor overload abnormality detection unit 41, 41': Moving average value calculation unit 42, 42 ': Determination unit 43: Instruction value switching unit M: Motor P: Transfer paper (recording medium)

Japanese Patent Laid-Open No. 2015-33298

Claims (12)

A motor overload abnormality detection device that detects a motor overload abnormality based on a motor drive instruction value calculated according to a rotation speed of the motor, and outputs a motor drive instruction value according to the detection result,
A moving average value for obtaining a motor driving instruction value calculated according to the rotation speed of the motor for each section of a predetermined time and calculating a moving average value of the motor driving instruction value in a predetermined number of sections including the latest section A calculation means;
A determining means for comparing the moving average value calculated by the moving average value calculating means with a preset threshold value to determine the presence or absence of an overload abnormality;
When the determination means determines that there is no overload abnormality, a motor drive instruction value corresponding to the motor drive instruction value calculated according to the rotation speed of the motor is output, and the determination means determines that there is an overload abnormality. In this case, the motor overload abnormality detecting device includes an instruction value switching unit that switches the output motor drive instruction value to zero or a value lower than the calculated motor drive instruction value.   The moving average value calculating means calculates and obtains a motor drive instruction value calculated according to the rotation speed of the motor for each predetermined time interval, and obtains a predetermined number of intervals including the latest interval. The motor overload abnormality detection device according to claim 1, wherein a moving average value of average values of the motor drive instruction values is calculated. A motor overload abnormality detection device that detects motor overload abnormality based on a motor drive current value and outputs a motor drive instruction value according to the detection result,
A moving average value calculating means for obtaining the motor driving current value for each section of a fixed time and calculating a moving average value of the motor driving current values in a predetermined number of sections including the latest section;
A determining means for comparing the moving average value calculated by the moving average value calculating means with a preset threshold value to determine the presence or absence of an overload abnormality;
If the determination means determines that there is no overload abnormality, a motor drive instruction value corresponding to the motor drive instruction value calculated according to the motor speed is output, and the determination means determines that there is an overload abnormality. In this case, the motor overload abnormality detection device includes: instruction value switching means for switching the output motor drive instruction value to zero or a value lower than the calculated motor drive instruction value.   The moving average value calculating means obtains the motor driving current value by calculating an average value of the motor driving current value for each section of a predetermined time, and moves the average value of the motor driving current value in a predetermined number of sections including the latest section. The motor overload abnormality detection device according to claim 3, wherein an average value is calculated.   If the determination means determines that there is an overload abnormality and the motor stop timing is not reached, the instruction value switching means is a motor corresponding to a motor drive instruction value calculated according to the rotation speed of the motor. The drive instruction value is output, the number of sections in which the state continues is counted, and the motor drive instruction value to be output is set to zero or the calculated motor for the counted number of sections after the motor stop possible timing is reached. The motor overload abnormality detection device according to any one of claims 1 to 4, wherein the motor overload abnormality detection device switches to a value lower than the drive instruction value. In the motor overload abnormality detection device according to claim 5,
A means is provided for forcibly stopping the motor when the number of sections that have not reached the motor stoppable timing exceeds a preset number of sections when the determination means determines that there is an overload abnormality. Motor overload abnormality detection device. In the motor overload abnormality detection device according to any one of claims 1 to 6,
The instruction value switching means is provided with means for notifying that an overload condition is present when the motor drive instruction value to be output is first switched to zero or a value lower than the calculated motor drive instruction value. Motor overload abnormality detection device. Speed detecting means for detecting the rotational speed of the motor;
A motor control unit for controlling the driving of the motor;
A motor drive circuit that is controlled by the motor control unit and drives the motor,
The motor control unit is
An instruction value calculation unit for calculating a motor drive instruction value based on the rotation speed of the motor detected by the speed detection unit;
The motor overload abnormality detection device according to claim 1 or 2,
A motor drive control device comprising: means for controlling the motor drive circuit in accordance with a motor drive command value output from the command value switching unit of the motor overload abnormality detection device. Speed detecting means for detecting the rotational speed of the motor;
A motor control unit for controlling the driving of the motor;
A motor drive circuit controlled by the motor control unit to drive the motor;
Motor drive current detection means for detecting the drive current of the motor,
The motor control unit is
An instruction value calculation unit for calculating a motor drive instruction value based on the rotation speed of the motor detected by the speed detection unit;
The motor overload abnormality detection device according to claim 3 or 4,
A motor drive control device comprising: means for controlling the motor drive circuit in accordance with a motor drive command value output from the command value switching unit of the motor overload abnormality detection device.   An image forming apparatus comprising: the motor drive control device according to claim 8; and a motor driven and controlled by the motor drive control device. A motor overload abnormality detection method for detecting a motor overload abnormality based on a motor drive instruction value calculated according to a motor rotation speed and outputting a motor drive instruction value according to the detection result,
A moving average value for obtaining a motor driving instruction value calculated according to the rotation speed of the motor for each section of a predetermined time and calculating a moving average value of the motor driving instruction value in a predetermined number of sections including the latest section Calculation procedure,
A determination procedure for comparing the moving average value generated in the moving average value calculation procedure with a preset threshold value to determine the presence or absence of an overload abnormality;
If it is determined that there is no overload abnormality in the determination procedure, a motor drive instruction value corresponding to the motor drive instruction value calculated according to the rotation speed of the motor is output, and it is determined that there is an overload abnormality in the determination procedure. And a command value switching procedure for switching the output motor drive command value to zero or a value lower than the calculated motor drive command value. A motor overload abnormality detection method for detecting an overload abnormality of a motor based on a motor drive current value and outputting a motor drive instruction value according to the detection result,
A moving average value calculating procedure for obtaining the motor driving current value for each section of a fixed time and calculating a moving average value of the motor driving current values in a predetermined number of sections including the latest section;
A determination procedure for comparing the moving average value calculated in the moving average value calculation procedure with a preset threshold value to determine the presence or absence of an overload abnormality;
If it is determined that there is no overload abnormality in the determination procedure, a motor drive instruction value corresponding to the motor drive instruction value calculated according to the motor rotation speed is output, and it is determined that there is an overload abnormality in the determination procedure. In this case, the motor overload abnormality detecting method includes: an instruction value switching procedure for switching the output motor drive instruction value to zero or a value lower than the calculated motor drive instruction value.