JP2006325839A - Motor driving device and washing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely detect the unbalance with consideration of the acceleration/deceleration of a motor while the unbalance is being detected. <P>SOLUTION: The motor is driven to detect the unbalance of the laundry during the dewatering operation. The rotational frequency of the motor is detected in a prescribed period of one rotation of the motor. The acceleration or deceleration of the motor in the period is determined based on the detected rotational frequency of the motor, and the rotational frequency of the motor is corrected according to the acceleration/deceleration. The difference between the maximum rotational frequency and the minimum rotational frequency of the motor in the prescribed period is computed from the corrected rotational frequency of the motor as the degree of variation of the rotation of the motor, and whether the laundry is unbalanced or not is determined based on the difference and a threshold. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor driving device for rotationally driving a rotating container that contains a stored item, and more particularly to a motor driving device for a washing machine that uses a rotating drum as a rotating drum that stores laundry.

  In the washing machine, there has been proposed one that detects an unbalance of the laundry from the rotation speed fluctuation of the rotating drum and controls the motor speed by an inverter circuit. Conventionally, this type of washing machine is configured as described in Patent Documents 1 to 3. That is, a motor directly connected to the rotating drum is driven so as to have a substantially constant rotation, and a fluctuation in the number of rotations per one rotation of the motor is detected. The rotational speed fluctuation value is compared with a threshold value to detect the degree of dehydration vibration, and the dehydration rotation is controlled based on the detection result.

  For example, in FIG. 8, the maximum value Rmax1 and the minimum value Rmin1 of the rotation speed during one rotation of the motor from time T10 to T11 are measured. If the deviation ΔR1 (= Rmax1-Rmin1) is larger than the threshold value, it is determined that the state is unbalanced.

  Here, in order to increase the detection accuracy, it is important to drive the motor so that the rotation is substantially constant. In Patent Document 1, the duty ratio of the switching element in the inverter circuit is controlled to be constant, and in Patent Document 2, predetermined constant power is supplied to the motor.

In particular, in Patent Document 3, the motor current is decomposed into a current component corresponding to the magnetic flux and a current component corresponding to the torque, respectively controlled, and the load imbalance of the washing and dewatering tub is detected from a change in the rotational speed of the rotor. ing. As a result, constant torque control can be performed by vector control of the motor current, and load imbalance can be accurately detected from the rotational speed fluctuation during the constant torque control period.
JP-A-4-31496 Japanese Patent Laid-Open No. 2001-120881 JP 2003-265883 A

  However, during the dehydration operation, the motor accelerates or decelerates slightly, and the motor rotation speed at the start and end of unbalance detection changes. For example, FIG. 9 shows changes in the motor rotation speed when the motor is accelerated during unbalance detection with the same unbalance amount as that shown in FIG. At the end of the unbalance detection, the motor speed is higher.

  The deviation ΔR2 obtained from the maximum value Rmax2 and the minimum value Rmin2 of the rotation speed during one rotation of the motor from time T20 to T21 is smaller than the deviation ΔR1 in FIG. That is, although the same unbalanced state and the washing machine have the same degree of vibration, the motor accelerated slightly during the unbalance detection period. Has occurred.

  For this reason, the degree of vibration cannot be accurately detected, and an unbalanced state is erroneously determined. If it is erroneously determined that there is no imbalance, the dehydration operation is continued as it is, and the vibration of the washing machine increases. Or, in spite of the fact that the degree of vibration is actually small, there is a problem that it is erroneously determined to be unbalanced and the operation is stopped.

  In view of the above, an object of the present invention is to provide a motor drive device that can accurately detect imbalance in consideration of acceleration / deceleration of the motor during the imbalance detection period.

  According to the present invention, a motor that rotationally drives a rotating container that contains a container, a rotation detection unit that detects the number of rotations of the motor, and an unbalance of the container from the degree of fluctuation of the motor rotation during a predetermined period. An unbalance detector, and the unbalance detector corrects the degree of variation based on the initial motor rotation of the predetermined period and the last motor rotation of the predetermined period.

  Specifically, the difference between the initial motor rotation speed and the last motor rotation speed for a predetermined period is calculated, and the motor rotation speed detected during the predetermined period is corrected according to the difference. That is, the unbalance detection unit determines the acceleration / deceleration of the motor during a predetermined period from the calculated difference, and corrects the variation degree according to acceleration or deceleration. The determination of the acceleration / deceleration of the motor is based on the magnitude of the initial motor rotation speed and the last motor rotation speed, and is accelerated when the motor rotation speed is increased and is decelerated when the motor rotation speed is decreased.

  When the motor is accelerating, the unbalance detection unit corrects so that the degree of fluctuation increases. At this time, the motor rotational speed is reduced by the correction. When the motor is decelerating, correction is made so that the degree of fluctuation becomes small. At this time, the motor speed increases due to the correction.

  Then, the imbalance is detected based on the corrected fluctuation degree of the motor rotation. When the variation degree is larger than the threshold value, it is determined that it is unbalanced, and when the variation degree is smaller than the threshold value, it is determined that it is not unbalanced.

  Note that constant torque control or constant rotation control is performed during a predetermined period. As a result, the magnitude of the acceleration / deceleration of the motor during the predetermined period can be kept small, the error of the fluctuation degree of the motor rotation is reduced, and the imbalance detection accuracy is increased. The predetermined period is a period in which the rotating container rotates n (n is a natural number). When the motor rotationally drives the rotating container by the direct drive method, the rotation of the rotating container corresponds to the motor rotation speed.

  According to the present invention, when detecting the imbalance of the contents accommodated in the rotating container, it is possible to detect the exact degree of fluctuation by correcting the degree of fluctuation of the motor rotation according to the acceleration / deceleration of the motor. As a result, the imbalance detection accuracy increases. In particular, in the washing machine, when the laundry imbalance is detected as described above, erroneous detection of the imbalance is eliminated, and the dehydration operation can be performed efficiently.

  As shown in FIG. 1, the motor drive device according to the present invention drives and controls a motor 1, which is a three-phase four-pole permanent magnet synchronous motor, mounted on an electric device by inverter control by an inverter circuit 2. The inverter circuit 2 is supplied with a three-phase voltage signal Vu *, Vv *, Vw * from a microcomputer 3 (hereinafter referred to as a microcomputer 3) as a control device, and outputs an applied voltage to the motor 1 based on this signal. . Further, the converter circuit 4 forms a DC power source from the AC power source 5 and supplies power to the inverter circuit 2.

  The microcomputer 3 generates the three-phase voltage signals Vu *, Vv *, and Vw * according to the program using the rotor position signal detected by the rotor position detector 6 and the motor current detected by the motor current detectors 7a and 7b. And output to the inverter circuit 2. The inverter circuit 2 outputs voltages Vu, Vv, Vw for driving the motor 1 to the motor 1 according to the voltages Vu *, Vv *, Vw * input from the microcomputer 3. Control of the motor 1 using the inverter circuit 2 is performed using a method generally called vector control. Since vector control is a well-known technique, description thereof is omitted here. By the vector control, the motor 1 can be driven with a stable torque.

  In addition, by using a permanent magnet type synchronous motor as the motor 1, it is possible to operate more efficiently than an induction motor or the like, and it is possible to control motor torque with higher accuracy by combining with vector control. .

  The rotor position detector 6 uses a hall sensor. As a result, the rotor position detection circuit can be configured at low cost. When three hall sensors are used, rotor position signals Hu, Hv, and Hw as shown in FIG. 2 are output from the hall sensors and input to the microcomputer 3.

  The microcomputer 3 has a rotation detector 8 that calculates the motor rotation speed based on the rotor position signal. Specifically, the rising or falling edge of the rotor position signal is measured using the timer function of the microcomputer 3. Since the edge generation interval and the motor rotation number are in an inversely proportional relationship, the motor rotation number can be calculated from the edge generation interval. Thus, by using the rotor position detector 6 used for driving control of the motor 1, the motor rotation speed can be detected without any special additional parts.

  A washing machine is an example of an electric device equipped with the motor driving device. The washing machine is a drum-type washing / drying machine having a rotating drum. The rotating shaft of the cylindrical rotating drum is provided in the horizontal direction with respect to the floor surface. The rotating shaft of the motor 1 is connected to the rotating shaft of the rotating drum without slipping. For this reason, the number of rotations of the motor and the number of rotations of the rotating drum have a corresponding relationship, and the number of rotations of the rotating drum can be detected without directly detecting the rotation of the rotating drum.

  Here, a direct drive system in which the motor 1 and the rotating drum are directly fixed is adopted. In this method, the torque generated by the motor 1 can be accurately transmitted to the rotating drum with little time delay. In addition, it is possible to extremely reduce the factors causing the rotation speed detection error such as slip, friction, and time delay in the rotation transmission path from the motor 1 to the rotating drum, and the detection accuracy is improved.

  The microcomputer 3 includes an unbalance detection unit 9 that detects unbalance caused by the laundry being shifted when the rotary drum rotates. That is, the unbalance detection unit 9 measures the motor rotation speed for a predetermined period during the dehydration operation, calculates the fluctuation degree of the motor rotation, and determines whether or not the imbalance is based on the fluctuation degree. At this time, the unbalance detection unit 9 considers the acceleration / deceleration of the motor 1 during the unbalance detection period, and determines the degree of fluctuation of the motor rotation based on the initial motor rotation speed and the last motor rotation speed for the predetermined period. to correct. Note that the degree of fluctuation of the motor rotation is calculated by the difference between the maximum motor rotation speed and the minimum motor rotation speed during a predetermined period. The determination of unbalance is made based on whether or not this difference exceeds a threshold value.

  The control operation of the microcomputer 3 relating to unbalance detection during dehydration in the washing machine will be described with reference to FIG. First, based on the rotor position signal from the rotor position detector 6, it is detected that the motor 1 is stopped and the rotating drum is not moving (S1), and then the rotation of the motor 1 is started (S2).

  The motor 1 is accelerated to a predetermined number of rotations for detecting unbalance (S3). At this time, the predetermined number of rotations is a number of rotations such that the centrifugal force to be attached to the rotating drum is larger than the gravity at which the laundry is about to fall.

  Thereafter, the motor 1 is driven at the predetermined rotational speed for a certain period (S4). At this time, the motor torque command value in the vector control for maintaining a predetermined number of rotations changes from moment to moment depending on the unbalanced state of the stuck laundry. After a certain period of time, the update of the motor torque command is stopped (S5). That is, the constant rotation control is switched to the constant torque control.

  Next, the motor rotation speed for a predetermined period is detected. That is, the instantaneous motor rotation speed is periodically detected such that the mechanical angle is 0 degree, the mechanical angle is 30 degrees, and the mechanical angle is 60 degrees. Every time the rising edge or falling edge of the rotor position signal as shown in FIG. 2 occurs, the edge generation interval is measured using the timer function of the microcomputer 3. Then, the instantaneous motor rotational speed is detected by calculating the rotational speed from the edge generation interval.

  Until the rotation drum makes one rotation and reaches a mechanical angle of 360 degrees (= mechanical angle 0 degree), for example, the motor rotation number is detected 13 times for every rotation of the mechanical angle of 30 degrees. This data is stored as a variable name Rx (x is 0 to 12) in a RAM which is a temporary detection data storage unit in the microcomputer 3 (S6).

The motor 1 is driven at a rotational speed that is not much different from a predetermined rotational speed even when the motor torque command is not updated for a period of one rotation of the rotating drum (one rotation of the motor 1), that is, in a constant torque state. Continue. However, there is slight acceleration or deceleration, and the motor rotational speed Rs at the start of unbalance detection is different from the motor rotational speed Re at the end. Therefore, the degree of acceleration or deceleration during a predetermined period for detecting imbalance is obtained. That is, since a difference occurs between Rs and Re, the degree of acceleration or deceleration is obtained from Rs and Re. And the fluctuation | variation degree of motor rotation is correct | amended by correct | amending motor rotation speed according to the degree of acceleration / deceleration. From the following formula (1), Rx is corrected, and the corrected motor rotational speed is stored as a variable name RHx (S7).
RHx = Rx + x / m × (Rs−Re) (1)
However, x is 0-12, m = 12, Rs = R0, Re = R12.

  Then, in the corrected motor rotational speed, a difference between the maximum motor rotational speed and the minimum motor rotational speed is obtained, and based on this difference, it is determined whether or not there is an imbalance. By determining the imbalance based on the degree of variation corrected in this way, it is possible to detect the imbalance with high accuracy in consideration of the acceleration / deceleration of the motor 1.

  4 to 6 show the motor rotation speed before and after correction. FIG. 4 shows that R0 and R12 are the same, and there is no acceleration / deceleration. FIG. 5 shows that when R12 is increased compared to R0. FIG. 6 shows that R12 is reduced compared to R0. It is a case. Each data is data when acceleration / deceleration of the motor 1 is performed in the same unbalanced state. In the figure, (a) is data of the detected motor speed, and (a ′) is data. , (A) is graphed. (B) is data of the motor rotation number after correction, and (b ′) is a graph of the data of (b).

  The deviation ΔR between the maximum value and the minimum value of the motor rotational speed, which is the degree of fluctuation of the motor rotational speed, is 60 in FIG. 4 (a), 48 in FIG. 5 (a), and 72 in FIG. 6 (a). Originally, the same deviation ΔR should have different values, and an error has occurred in the degree of fluctuation of the motor rotation.

  Therefore, the fluctuation degree of the motor rotation is corrected. When the deviation ΔRH between the maximum value and the minimum value of the motor rotational speed is obtained (S8), it becomes 60 in FIG. 4B, 60 in FIG. 5B, and 60 in FIG. Can be eliminated.

  The corrected deviation ΔRH is compared with the threshold value A1 (S9), and it is determined whether or not the laundry is unbalanced. When ΔRH is larger than the threshold value A1, it is determined that there is an imbalance. Once the motor 1 is decelerated (S10), the laundry is separated, and the process returns to S3 again. Therefore, the washing machine can be prevented from greatly vibrating due to the unbalance of the laundry.

  On the other hand, if ΔRH is smaller than the threshold value A1, it is determined that there is no imbalance, the motor 1 is accelerated (S11), and high-speed dewatering rotation is performed (S12). Thus, since imbalance can be detected with high accuracy, erroneous detection of imbalance is eliminated, unnecessary driving such as deceleration and reacceleration of the motor 1 is eliminated, and the dehydration rate can be improved and the dehydration time can be shortened.

In the above embodiment, the deviation ΔRH between the maximum value and the minimum value of the motor rotation speed during one rotation of the motor 1 is used as the parameter of the fluctuation degree. However, as shown in the following equation (2), the detected instantaneous The maximum value RSmax of the absolute value RSx of the difference between the motor rotation speed Rx and the reference rotation speed RKx may be used as a parameter for the degree of motor rotation fluctuation.
RSx = | Rx−RKx | (2)
Here, in consideration of the influence of acceleration or deceleration of the motor 1 during a predetermined period, the reference rotational speed RKx at the time of detection is determined in accordance with the acceleration / deceleration of the motor 1 according to the following equation (3).
RKx = Rs + x / m × (Re−Rs) (3)
Where x is an integer from 0 to m, Rs is the motor speed at the start of the predetermined period, and Re is the motor speed at the end of the predetermined period.

  FIG. 7 shows data of (a) R0 to R12, (b) RK0 to RK12, and (c) RS0 to RS12. As a result, RSmax is 30.

  Next, the calculated RSmax is compared with the threshold value A2 as a parameter of the degree of motor rotation fluctuation, and the laundry imbalance is detected. Since other operations are the same as those in the above embodiment, the description thereof is omitted.

  In addition, although the unbalance of the laundry was judged from the fluctuation | variation degree of the motor rotation speed during 1 rotation of the motor 1, the predetermined period for detecting an unbalance does not need to be limited to this, The motor 1 It is good also as a period rotated several times. In this case, the time required for unbalance detection becomes longer, but the detection error becomes smaller.

  For example, the instantaneous motor rotation speed during two rotations of the motor 1 is detected 25 times every rotation of the mechanical angle of 30 degrees, and this data is stored in the RAM in the microcomputer 3 as variable names R0 to R24. By the same method as in the above embodiment, R0 to R24 are corrected using R0 and R24 which are rotation speeds at the start and end of imbalance detection, and RH0 to RH24 are calculated. The imbalance of the laundry is detected from the deviation ΔRH between the maximum value and the minimum value of the motor rotational speed after correction.

  Alternatively, the predetermined period may be plural. Each predetermined period may be continuous or may have a fixed time interval. For example, every time the motor 1 makes one rotation, the deviation ΔRH between the maximum value and the minimum value of the motor rotation number is calculated, and after rotating a plurality of times, the average value of the plurality of ΔRH is compared with the threshold value A1, thereby An imbalance may be detected.

  Further, control is performed to keep the torque constant during the period in which the laundry unbalance is detected, but it is sufficient that the motor 1 can be driven to rotate at a substantially constant speed during this period. Therefore, instead of keeping the torque constant, control may be performed to keep power, voltage, or current supplied to the inverter circuit 2 constant and the rotation speed constant. Even in this case, since the motor speed fluctuates slightly, there is an effect of correcting the degree of fluctuation of the motor speed as described above.

  By performing the drive control of the motor 1 as described above, the magnitude of acceleration or deceleration of the motor 1 during a predetermined period for detecting imbalance can be reduced. Accordingly, the detection error of the fluctuation degree of the motor rotation can be reduced, and the imbalance detection accuracy is increased. Further, since the permanent magnet type synchronous motor is used, the motor torque can be controlled with higher accuracy than the induction motor. Therefore, an unbalanced state can be detected more accurately by performing constant torque control or constant rotation control.

  In the above embodiment, the laundry unbalance is detected from the degree of fluctuation of the motor rotation during one rotation of the motor 1, but the motor rotation speed and the edge generation interval of the rotor position signal are in an inversely proportional relationship. Focusing on the fact that the motor rotation speed is obtained by calculation from the edge generation interval of the rotor position signal, instead of the motor rotation speed, the laundry is calculated from the degree of fluctuation of the edge generation interval of the rotor position signal during one rotation of the motor 1. May be detected. Further, the rotation of the rotating drum may be directly detected instead of the motor rotation speed.

  In addition, this invention is not limited to the said embodiment, Of course, many corrections and changes can be added to the said embodiment within the scope of the present invention. The motor drive device of the present invention may be used as a motor drive device for a washing machine or a drum dryer in which the rotating container rotates around the vertical axis, in addition to the drum type washing machine. You may use for the electric equipment rotated with a motor like the stirring apparatus which accommodates and stirs a granule.

The block diagram which shows schematic structure of the motor drive device of this invention The figure which shows the output signal when detecting the rotor position of the motor Flow chart of control operation at the time of laundry imbalance detection A diagram showing the motor speed before and after correction when there is no motor acceleration / deceleration The figure which shows the motor rotation speed before and after correction when the motor accelerates The figure which shows motor rotation speed before and after correction when the motor decelerates The figure explaining the detection of the fluctuation degree of the motor rotation by other embodiment The figure which shows the fluctuation degree of motor rotation due to unbalance The figure which shows the fluctuation degree of the motor rotation due to imbalance when the motor accelerates

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Inverter circuit 3 Microcomputer 4 Converter circuit 5 AC power supply 6 Rotor position detection part 8 Rotation detection part 9 Unbalance detection part

Claims (10)

A motor that rotationally drives the rotating container that contains the contents, a rotation detector that detects the number of rotations of the motor, and an unbalance detector that detects an imbalance of the contents from the degree of fluctuation of the motor rotation during a predetermined period. And the unbalance detection unit corrects the degree of variation based on the initial motor rotation of the predetermined period and the final motor rotation of the predetermined period. The unbalance detection unit calculates a difference between an initial motor rotation speed and a last motor rotation speed for a predetermined period, and corrects the motor rotation speed detected during the predetermined period according to the difference. Item 2. The motor drive device according to Item 1. A motor that rotationally drives the rotating container that contains the contents, a rotation detector that detects the number of rotations of the motor, and an unbalance detector that detects an imbalance of the contents from the degree of fluctuation of the motor rotation during a predetermined period. And the unbalance detection unit determines acceleration / deceleration of the motor during the predetermined period, and corrects the variation degree according to acceleration or deceleration. 4. The motor drive apparatus according to claim 3, wherein the unbalance detection unit corrects the fluctuation degree to be large when the motor is accelerating, and corrects the fluctuation degree to be small when the motor is decelerating. . The motor driving apparatus according to claim 1, wherein constant torque control or constant rotation control is performed during a predetermined period. The motor driving apparatus according to claim 1, wherein the unbalance detection unit detects unbalance during a predetermined period in which the rotating container rotates n (n is a natural number). The unbalance detection unit calculates a fluctuation degree of the motor rotation based on a difference between the maximum motor rotation speed and the minimum motor rotation speed during a predetermined period, and determines whether or not the unbalance is based on the magnitude of the fluctuation degree. The motor drive device in any one of Claims 1-5. 8. The motor driving apparatus according to claim 6, wherein the motor is a brushless motor including a rotor having a permanent magnet and a stator around which a three-phase winding is wound. 9. The motor driving apparatus according to claim 8, wherein the motor rotationally drives the rotary container by a direct drive system. A washing machine comprising the motor driving device according to any one of claims 1 to 9.

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