JP5261070B2 - DC motor rotation state detection device and DC motor control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation state detection device for a DC motor capable of detecting a rotation state of the DC motor using ripple pulses, and determining a detection ability of the rotation state using the ripple pulses. <P>SOLUTION: The rotation state detection device includes a ripple pulse generating part 3 which converts ripple components contained in a detected signal FO of a motor current after passing a filter 1 to a pulse waveform to generate ripple pulses RP, a low sensitivity pulse generating part 4 which converts the ripple components to the pulse waveform to generate a low sensitivity pulse LRP with sensitivity lower than that of the ripple pulse generating part 3, a rotation detecting part 6 which detects the rotation state of the DC motor M based on the ripple pulses RP, and a detection ability determination part 7 which determines the reduction of the detection ability for the rotation state by the rotation detecting part 6, when the number of pulses of the low sensitivity pulses LRP within a predetermined determination period is lower than that of the ripple pulses RP. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a rotational state detection device for a direct current motor that detects the rotational state of the direct current motor based on a ripple component included in the motor current of the direct current motor. The present invention also relates to a DC motor control device provided with the rotational state detection device.

  A vehicle capable of automatically adjusting a seat position and posture stored by a switch operation even when the seat position and posture are stored in a storage medium by a passenger and then the seat position and posture are changed. Sheet has been put to practical use. The change in the seat position and posture includes a slide that moves the entire seat back and forth, a reclining that changes the inclination of the seat back, and the like. In order to perform each changing operation, the vehicle seat is provided with a DC motor. In order to store the sheet position and posture and realize automatic adjustment to the stored sheet position, it is necessary to know the sheet position and posture. Since a DC motor is used to change the seat position and orientation, it is convenient to detect the seat position and orientation based on the rotational speed of the DC motor.

  The rotational speed of the DC motor can be detected by using a sensor such as an encoder, a resolver, or a Hall element. However, a technique for detecting the rotational speed of a DC motor more simply without using these sensors is known. Specifically, this is a technique for detecting the rotation of the motor by generating a ripple pulse from the ripple component of the motor current synchronized with the rotation of the DC motor. The ripple component is also a noise component, and it is necessary to clear various problems when generating a ripple pulse that accurately indicates the rotational speed from the ripple component.

  In JP-A-8-260811 (Patent Document 1), when a ripple pulse is detected based on a threshold value, the ripple pulse is accurately detected regardless of the difference in the amplitude of the ripple component that varies depending on the magnitude of the drive current. A technique for generating is disclosed. Here, a parameter value corresponding to the driving torque of the motor is detected, and a threshold value corresponding to the driving torque is set according to the detected parameter value. Since the magnitude of the drive current varies according to the drive torque, an appropriate threshold value is set.

  In Japanese Patent Laid-Open No. 7-305563 (Patent Document 2), a ripple signal detection is performed according to the frequency of the ripple signal detected by the ripple detection circuit so that the ripple signal can be accurately detected even when the motor rotates at a low speed. The frequency characteristics of the circuit are switched.

  Japanese Patent Laid-Open No. 2000-116168 (Patent Document 3) discloses a technique for removing a noise component that varies depending on the number of rotations and the like and solving a problem in accurately detecting a ripple pulse from a ripple component. In view of the fact that switching control by software or hardware becomes difficult when the noise filter is multistaged to cope with various noises and the cutoff frequency is switched in multiple stages, a technique for linearly changing the cutoff frequency is disclosed.

  By the way, a DC motor has a mechanical contact between a brush and a commutator, and the brush is likely to change with time due to wear or the like. As a result, electrical contact between the brush and the commutator becomes intermittent, and high-frequency noise such as impulse noise may occur. Japanese Patent Application Laid-Open No. 2000-333485 (Patent Document 4) discloses a filter means for changing a cutoff frequency to remove such noise and a clock generating means for generating a clock for changing the cutoff frequency of the filter means. A pulse generation circuit is disclosed.

  Japanese Patent Laying-Open No. 2003-9585 (Patent Document 5) discloses a circuit in which the circuit of Patent Document 4 is further improved. The circuit of Patent Document 5 suppresses the possibility that the adjustment of the cut-off frequency will be delayed when the rotational speed of the DC motor changes suddenly at high revolutions, or that the adjustment of the cut-off frequency will become unstable at low revolutions. Therefore, it is improved. In the circuit of Patent Document 5, the cutoff frequency of the switched capacitor filter is calculated in accordance with the frequency difference between the feedback amount calculated based on the actual ripple frequency and the maximum ripple frequency. Therefore, an appropriate ripple pulse can be obtained by appropriately following the switched capacitor filter without being affected by a change in the frequency of the ripple pulse output.

  Japanese Patent Application Laid-Open No. 2007-124865 (Patent Document 6) updates the cutoff frequency of a filter (active filter) that can determine whether or not the motor is rotating in a steady manner and makes the cutoff frequency variable as described above. Techniques for controlling are disclosed. That is, since the frequency of the ripple component is stable during steady rotation, the cutoff frequency of the filter is fixed without updating the cutoff frequency of the active filter. On the other hand, when the rotation is not steady, the frequency of the ripple component is not stable, so the cutoff frequency of the active filter is updated.

JP-A-8-260811 (3rd to 10th paragraphs, etc.) JP-A-7-305563 (3rd to 5th paragraphs, etc.) JP 2000-116168 (paragraphs 5-17) JP 2000-333485 A (paragraphs 4 to 11 etc.) Japanese Patent Laid-Open No. 2003-9585 (4th to 6th, 30th paragraph, etc.) JP 2007-124865 A (6th to 12th paragraphs, etc.)

  In the case of a general DC motor that is widely known, that is, a motor in which two brushes are mechanically arranged at a position of 180 degrees around the rotation axis, the switching timing of the two brushes is the same time. For example, a circuit as disclosed in Patent Document 5 functions very effectively. However, in the case of a motor in which two brushes are arranged at a 90-degree position around the rotation axis, the switching timing of the two brushes is alternately repeated, which has the following problems. . When non-uniformity occurs in the contact time between the brush and the commutator due to aging of the motor, noise of low frequency components is generated. When the amplitude of the noise of this low frequency component increases to some extent, the cutoff frequency of the switched capacitor filter is gradually adjusted to the low frequency side, and the original ripple component is also cut off or smoothed. There is a possibility. Further, when noise on the high frequency side increases, more ripple pulses than the original number of ripples may be generated.

  As a result, the reliability of the detection result of the rotation state based on the ripple pulse is reduced, and the convenience is impaired when the detection accuracy of the position and orientation of the sheet as described above is reduced. In addition, as described above, such a problem due to an increase in noise components often occurs due to wear of a brush that is a sliding member. In addition, it is preferable that the DC motor causing such wear is subjected to maintenance such as replacement of parts. Therefore, rather than increasing the circuit scale or increasing the cost to separate or suppress noise components due to aging, the operation of the device driven by the DC motor is detected. It is preferable to limit or inform the user of the necessity of maintenance.

  The present invention was devised in view of the above problems, and can detect a rotational state of a DC motor using a ripple pulse and determine a rotational state detection capability using the ripple pulse. An object of the present invention is to provide a rotational state detection device.

In order to achieve this object, the characteristic configuration of the rotational state detection device according to the present invention is:
A rotational state detection device for a direct current motor that detects the rotational state of the direct current motor based on a ripple component included in the motor current of the direct current motor,
A filter that removes a high-frequency noise component from the motor current detection signal;
The ripple pulse is converted into a pulse waveform based on the depth of the valley of the ripple component included in the detection signal of the motor current after passing through the filter and the ratio set to the height of the peak of the ripple component. A ripple pulse generator for generating
A calculation unit that calculates a cutoff frequency of the filter based on the detection signal of the motor current and the ripple pulse, and sets the cutoff frequency in the filter;
A low-sensitivity pulse that generates a low-sensitivity pulse by converting the ripple component into a pulse waveform based on a ratio larger than the ratio used when the ripple pulse generator converts the pulse waveform into a pulse waveform and the valley depth of the ripple component. A sensitivity pulse generator,
A rotation detector that detects a rotation state of the DC motor based on the ripple pulse;
A detection capability determination unit that determines a decrease in the detection capability of the rotation state by the rotation detection unit when the number of pulses of the low sensitivity pulse within a predetermined determination period is less than the number of pulses of the ripple pulse. .

  According to this characteristic configuration, in addition to the ripple pulse generator, the low-sensitivity pulse generator that generates a pulse with lower sensitivity than the ripple pulse generator is provided. When the low-frequency noise component increases in the motor current, the ripple component in the detection signal of the motor current after passing through the filter is likely to be rounded, and the pulse conversion in the ripple pulse generation unit is difficult to be performed. The pulse conversion in the low-sensitivity pulse generation unit is performed based on a criterion with lower sensitivity than the pulse conversion in the ripple pulse generation unit. Therefore, before the pulse conversion in the ripple pulse generator becomes difficult to be performed, the ripple component becomes apparent in the pulse conversion result in the low sensitivity pulse generator. According to the present embodiment, it is possible to determine a decrease in the detection ability of the rotation state by the rotation detection unit by comparing the number of pulses of the ripple pulse and the low sensitivity pulse. As a result, it is possible to provide a rotational state detection device for a direct current motor that can detect the rotational state of the direct current motor using the ripple pulse and determine the rotational state detection capability using the ripple pulse. Become.

  Moreover, it is preferable that the rotation state detection device according to the present invention includes a notification unit that notifies a decrease in the rotation state detection capability by the rotation detection unit based on the determination result of the detection capability determination unit.

  By providing the notification unit, it is possible to notify the control device that performs various controls in response to the detection result of the rotation state detection device of the DC motor, about the decrease in the detection capability of the rotation state detection device. The control device that has received the notification can limit the operation of the device driven by the DC motor or can further notify the necessity of maintenance of the DC motor, and the device on which the rotation state detection device is mounted The reliability of itself can be improved.

The rotation state detection device according to the present invention may further include the ripple component based on a ratio smaller than the ratio used when the ripple pulse generation unit converts the pulse waveform into a pulse waveform and a valley depth of the ripple component. A high-sensitivity pulse generator that generates a high-sensitivity pulse by converting the signal into a pulse waveform,
In the detection capability determination unit, the number of high-sensitivity pulses in the determination period exceeds the number of ripple pulses, and the number of low-sensitivity pulses in the determination period is less than the number of ripple pulses. In this case, it is preferable to determine that the rotation state detection capability of the rotation detection unit is not normal.

  According to this configuration, in addition to the ripple pulse generation unit and the low sensitivity pulse generation unit, the high sensitivity pulse generation unit that generates a pulse with higher sensitivity than the ripple pulse generation unit is provided. When a high-frequency noise component increases in the motor current, extra pulse conversion is easily performed in the ripple pulse generator. The pulse conversion in the high-sensitivity pulse generation unit is performed based on a higher sensitivity reference than the pulse conversion in the ripple pulse generation unit. For this reason, an extra pulse appears in the pulse conversion result in the high-sensitivity pulse generator before the extra pulse conversion is easily performed in the ripple pulse generator. Therefore, by comparing the number of pulses of the ripple pulse and the high-sensitivity pulse, it is possible to determine a decrease in the detection capability of the rotation state by the rotation detection unit. Further, in this state, if the number of pulses of the ripple pulse and the low sensitivity pulse is different, the reliability of whether or not the ripple pulse accurately pulse-converts only the ripple component becomes extremely low. Therefore, the detection capability determination unit can suppress a decrease in reliability of the rotation state detection device itself by determining that the rotation state detection capability of the rotation detection unit is not normal.

In addition, the rotation state detection device according to the present invention,
A high-sensitivity pulse is generated by converting the ripple component into a pulse waveform based on a ratio smaller than the ratio used when the ripple pulse generation unit converts the pulse waveform into a pulse waveform and the valley depth of the ripple pulse. A sensitivity pulse generator,
A storage unit that stores a determination result by the detection capability determination unit as a determination history,
The detection capability determination unit, based on the ripple pulse, the low sensitivity pulse, the high sensitivity pulse, and the determination history, a decrease in the detection capability of the rotation state by the rotation detection unit, a first determination, a second determination, The determination is performed by distinguishing at least four of the third determination and the fourth determination.
The third determination is not stored as the determination history, the number of pulses of the high sensitivity pulse in the determination period is the same as the number of pulses of the ripple pulse, and the pulse of the low sensitivity pulse in the determination period When the number is less than the number of pulses of the ripple pulse, it is determined that the detection ability of the rotation state by the rotation detection unit tends to decrease as the first determination,
The first determination is stored as the determination history, the number of high-sensitivity pulses in the determination period exceeds the number of ripple pulses, and the number of low-sensitivity pulses in the determination period is When the number of ripple pulses is the same, it is determined that the rotation state detection capability by the rotation detection unit is not normal as the second determination,
The first determination is not stored as the determination history, the number of pulses of the low sensitivity pulse in the determination period is the same as the number of pulses of the ripple pulse, and the pulse of the high sensitivity pulse in the determination period When the number exceeds the number of pulses of the ripple pulse, as the third determination, it is determined that the detection capability of the rotation state by the rotation detection unit tends to decrease,
The third determination is stored as the determination history, the number of pulses of the low sensitivity pulse in the determination period is less than the number of pulses of the ripple pulse, and the number of pulses of the high sensitivity pulse in the determination period is When the number of ripple pulses is the same, it is preferable to determine that the rotation state detection capability of the rotation detection unit is not normal as the fourth determination.

  As described above, when a high-frequency noise component increases in the motor current, extra pulse conversion is easily performed in the ripple pulse generation unit. Then, before the extra pulse conversion is easily performed in the ripple pulse generation unit, an extra pulse appears in the pulse conversion result in the high sensitivity pulse generation unit. Therefore, by comparing the number of pulses of the ripple pulse and the high-sensitivity pulse, it is possible to determine a decrease in the detection capability of the rotation state by the rotation detection unit. Further, as described above, by comparing the number of pulses of the ripple pulse and the low sensitivity pulse, it is also possible to determine a decrease in the rotation state detection capability by the rotation detection unit. The relationship of the number of pulses when the detection capability of the rotation state by the rotation detector is reduced depends on whether the influence of the low frequency component noise or the high frequency component noise is significant. Therefore, it is difficult to finely determine the rotation detection capability that gradually decreases due to long-term use of the DC motor only by determining the number of pulses each time. Therefore, by providing a storage unit that stores the determination result by the detection capability determination unit as a determination history, the determination history by the detection capability determination unit is used for determination by the detection capability determination unit. As a result, it is possible to make a detailed determination in at least two stages: “the ability to detect the rotation state by the rotation detector tends to decrease” and “the ability to detect the rotation state by the rotation detector is not normal”. .

  Here, further, as a fifth determination, the detection capability determination unit determines that the number of pulses of the high-sensitivity pulse in the determination period exceeds the number of pulses of the ripple pulse regardless of the determination history. When the number of low-sensitivity pulses in the period is less than the number of ripple pulses, it is preferable to determine that the rotation state detection capability of the rotation detection unit is not normal.

  A characteristic configuration of a DC motor control device according to the present invention is a DC motor control device including a DC motor rotation state detection device having any one of the above configurations, and the determination result of the detection capability determination unit Therefore, the driving of the DC motor is limited.

  The DC motor controller may limit the drive of the DC motor based on the determination result of the detection capability determination unit, and the DC motor may be improperly controlled based on the incorrect rotation state detection result. Is suppressed. As a result, it is preferable without reducing the convenience and reliability of the device itself using the DC motor.

Further, the DC motor control device according to the present invention includes a rotation state detection of the DC motor having a storage unit that stores a determination result by the detection capability determination unit as a determination history,
When the determination result of the detection capability determination unit is the first determination or the third determination, a notification that prompts maintenance of the DC motor is performed,
When the determination result of the detection capability determination unit is the second determination or the fourth determination, it is preferable to prohibit the driving of the DC motor.

  As described above, by providing the storage unit, the determination history by the detection capability determination unit can be used for the determination by the detection capability determination unit. As a result, it is possible to make a detailed determination in at least two stages: “the ability to detect the rotation state by the rotation detector tends to decrease” and “the ability to detect the rotation state by the rotation detector is not normal”. . Therefore, the DC motor control device can take appropriate measures based on the determination results of the two stages. That is, it is possible to delay the timing for restricting the driving of the DC motor, and it is possible to ensure reliability while suppressing a decrease in convenience of the device itself using the DC motor.

[First Embodiment]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking as an example a DC motor rotation state detection device 10 used in a seat position control device 20 (DC motor control device) for controlling a vehicle seat. FIG. 1 is a block diagram schematically showing the overall configuration of a seat position control device 20 that controls the position of each part (movable body) of a vehicle seat. The seat position control device 20 is configured with an ECU (electronic control unit) 21 as a core.

  A battery 25 is connected to the control unit 22 of the ECU 21 via a power circuit 24 inside the ECU 21. A positive terminal of the battery 25 is connected to the input interface 23 via the ignition switch 26. When the ignition switch 26 is turned on, a constant voltage (for example, 5 V) stabilized by the power supply circuit 24 is supplied to each part of the ECU 21.

  An operation switch 27 for adjusting the position (sheet state) of each part of the sheet is connected to the input interface 23. In this embodiment, the operation switch 27 includes slide switches 28a and 28b, reclining switches 29a and 29b, front vertical switches 30a and 30b, and lifter switches 31a and 31b.

  The slide switches 28a and 28b are operation switches that slide the entire seat forward or backward along a rail attached to the vehicle side. The reclining switches 29a and 29b are operation switches for moving the seat back supported rotatably with respect to the seat cushion forward or backward. The front vertical switches 30a and 30b are operation switches that move the front part of the seat cushion occupant sitting up or down vertically. The lifter switches 31a and 31b are switches that move the rear part of the seat cushion on which the occupant sits up or down.

  Further, four motors M (39 to 42) are connected to the control unit 22 via relays 43, respectively. These motors M (39 to 42) are DC motors. The relay 43 is composed of four relay pairs corresponding to the four DC motors M (39 to 42). Each DC motor M is connected to the control unit 22 through a corresponding set of relays. Each set of relays includes a pair of coils and a pair of switching terminals. When any one of the operation switches 27 is operated, energization of the set of coils corresponding to the operated switch is controlled by the control unit 22. As a result, the switching terminals of the corresponding set of relays are switched, and the motor M corresponding to the corresponding set of relays among the motors M (39 to 42) is independently driven in the normal direction or the reverse direction.

  Accordingly, the DC motor 39 (slide motor) rotates forward or reverse by operating the slide switches 28a and 28b to slide the entire sheet forward or backward. The DC motor 40 (reclining motor) rotates forward or reverse by operating the reclining switches 29a and 29b, and moves the seat back forward or backward. The DC motor 41 (front vertical motor) rotates forward or reverse by operating the front vertical switches 30a and 30b to move the front part of the seat cushion up or down. The DC motor 42 (lifter motor) rotates forward or reverse by operating the lifter switches 31a and 31b to move the rear part of the seat cushion up or down.

  In addition, the ECU 21 is provided with a rotation state detection device 10 that detects the rotation state of each DC motor M (39 to 42). The rotation state detection device 10 generates a ripple pulse RP synchronized with the rotation of the DC motor M by pulsing the ripple component included in the motor current flowing through the DC motor M, and the rotation of the DC motor M based on the ripple pulse RP. Detect state.

  FIG. 2 is a block diagram schematically showing the configuration of the rotation state detection device 10 of the DC motor M. As shown in FIG. The rotation state detection device 10 includes a switched capacitor filter 1, a ripple pulse generation unit 3, and a rotation detection unit 6. The switched capacitor filter 1 attenuates the high frequency noise component included in the motor current of the DC motor M in accordance with the set cutoff frequency. The ripple pulse generator 3 generates a pulse waveform from the ripple component of the motor current (motor current detection signal) in which the high frequency noise component is attenuated, and outputs a ripple pulse RP. The rotation detection unit 6 determines a rotation state such as the number of rotations of the DC motor M based on the ripple pulse RP. The set cutoff frequency used in the switched capacitor filter 1 is sequentially set according to the frequency of the ripple component and the like. Moreover, in this embodiment, although it comprises the three pulse production | generation parts (3-5) including the ripple pulse production | generation part 3, these are mentioned later for details.

  The rotation state detection device 10 includes a calculation unit 9 that calculates a set cutoff frequency of the switched capacitor filter 1. An A / D converter 8 that digitally converts a voltage signal V (motor current detection signal) corresponding to the motor current of the DC motor M and provides the arithmetic unit 9 to the arithmetic unit 9 is connected to the arithmetic unit 9. The calculation unit 9 is configured using, for example, a microcomputer. The A / D converter 8 may be built in the same microcomputer as the calculation unit 9.

  The calculation unit 9 calculates the actual ripple frequency by converting the frequency of the ripple pulse RP output from the ripple pulse generation unit 3, and sets the feedback amount based on the actual ripple frequency. Further, the calculation unit 9 calculates the maximum ripple frequency of the ripple component of the motor current output according to the rotation state of the DC motor M, and calculates the cutoff frequency according to the difference between the maximum ripple frequency and the actual ripple frequency. . Further, the arithmetic unit 9 updates the set cutoff frequency of the switched capacitor filter 1 based on the feedback amount and the cutoff frequency, and sets the updated set cutoff frequency in the switched capacitor filter 1. Since the technique for obtaining and updating the set cutoff frequency is known from the above-mentioned Patent Document 5 (Japanese Patent Laid-Open No. 2003-9585) and the like, detailed description thereof is omitted.

  When the DC motor M is operating, the current flowing through the coil (not shown) when the commutator (not shown) passes through the brush changes, and a ripple component is superimposed on the motor current. Therefore, if the ripple pulse generation unit 3 generates a pulse waveform from the ripple component and converts it into a ripple pulse RP, the rotation detection unit 6 refers to the ripple pulse RP and detects the rotation state of the DC motor M. be able to. However, since the motor current contains a high-frequency noise component, the noise is removed by passing it through a filter (switched capacitor filter 1) having a preset cutoff frequency in advance, and then converted into a ripple pulse RP. . Further, since the frequency of the high-frequency noise component sequentially changes due to a change in the rotational speed of the DC motor M, the set cutoff frequency is also updated sequentially following the change.

  In the rotation state detection device 10 for the DC motor M according to the present invention, the ripple output from the ripple pulse generation unit 3 in parallel with the rotation detection unit 6 detecting the rotation state (the number of rotations, etc.) of the DC motor M. The pulse RP is fed back to the calculation unit 9. Then, the set cutoff frequency is sequentially updated based on the feedback input. If the DC motor M is rotating at a constant speed, that is, if the frequency of the ripple pulse RP is stable, a value between the two frequencies is used to separate the ripple pulse frequency and the frequency of the high frequency noise. There is no need to update the set cutoff frequency to be set. Therefore, the calculation unit 9 permits the set cutoff frequency to be updated when the DC motor M is not rotating at a constant speed, and allows the set cutoff frequency to be updated when the DC motor M is rotating at a constant speed. You may perform the determination which is not permitted.

  In recent years, in automobiles, various members such as windows, doors, and seats are electrically driven. For this reason, many motors are mounted on one vehicle, and there is an increasing demand for miniaturization and weight reduction for one motor. And as one of the technologies for miniaturizing the motor, a device in which the arrangement of the brush of the DC motor is devised has been proposed. Conventionally, the two brushes of a DC motor have been mechanically arranged with a spatial phase difference of 180 degrees around the rotation axis of the motor. However, a direct current motor that realizes a small size by arranging the brushes with a spatial phase difference of 90 degrees has been proposed and put into practical use.

  In the case of a general DC motor in which brushes are arranged with a difference of 180 degrees, the timing at which the direction of current flow is switched by the brushes is the same time. Therefore, when the DC motor is rotating at a constant speed, a ripple component appears at a constant frequency. Even if the DC motor is used for a long time, the brush is worn, and the amplitude of the ripple component fluctuates, the influence of the ripple component on the frequency is small. However, in the case of a motor in which the brush is disposed at a position of 90 degrees, if nonuniformity occurs in the contact time between the brush and the commutator due to wear or the like, noise of a low frequency component is generated. When the amplitude of the noise of the low frequency component increases to some extent, the cutoff frequency of the switched capacitor filter 1 is gradually adjusted to the low frequency side, which may attenuate the original ripple component. .

  Thus, if even the original ripple component is attenuated, the ripple pulse RP that passes through the switched capacitor filter 1 and is generated by the ripple pulse generator 3 will be lost. As a result, the accuracy of determination results such as the rotational speed of the DC motor M determined by the rotation detection unit 6 based on the ripple pulse RP is impaired. On the other hand, when the noise on the high frequency side increases, more ripple pulses RP than the original number of ripples are generated, and there is a possibility that the determination accuracy by the rotation detector 6 is also lowered.

  Therefore, the DC motor rotation state detection device 10 according to the present invention includes three pulse generation units (3 to 5) including the ripple pulse generation unit 3 to suppress such a problem. Specifically, in addition to the ripple pulse generator 3, a low sensitivity pulse generator 4 and a high sensitivity pulse generator 5 are provided. The low sensitivity pulse generation unit 4 is a functional unit that generates a low sensitivity pulse LPR by converting a ripple component into a pulse waveform with lower sensitivity than the ripple pulse generation unit 3. The high-sensitivity pulse generation unit 5 is a functional unit that generates a high-sensitivity pulse MRP by converting a ripple component into a pulse waveform with higher sensitivity than the ripple pulse generation unit 3.

  In the present embodiment, the pulse generators 3 to 5 are configured using a microcomputer, and the functions thereof are realized by the cooperation of hardware and a program (software). In this embodiment, the output FO of the switched capacitor filter 1 is A / D converted by the A / D converter 2 and input to each of the pulse generators 3 to 5. In addition, this A / D converter 2 may be built in the microcomputer which comprises the pulse generation parts 3-5. In addition, the functional units of the A / D converter 8, the arithmetic unit 9, the A / D converter 2, and the pulse generators 3 to 5 described above may be configured using the same microcomputer.

  FIG. 3 is a waveform diagram schematically showing an example of the relationship between the ripple component of the motor current at normal times and the three pulse waveforms. In the figure, the symbol FO indicates the ripple waveform of the motor current detection signal V after passing through the switched capacitor filter 1. When the rotation detection unit 6 maintains the rotation state detection capability and is in a state in which the rotation state can be normally detected, as shown in FIG. 3, three types of pulses (RP, MRP, LRP) is generated. Here, “substantially the same timing” is because the three pulse generation units (3 to 5) perform pulse conversion with different sensitivities, and therefore, pulses having completely the same timing are not obtained.

  FIG. 4 is an explanatory diagram showing the principle of pulse conversion. As an example, the pulse generators 3 to 5 perform pulse conversion based on the relationship between the “peak height H” and the “valley depth D” of the ripple component as shown in FIG. 4. When pulse conversion is performed even if the valley depth D is shallow with respect to the mountain height H, the conversion sensitivity is high. If the valley depth D is not deep with respect to the mountain height H, the pulse conversion is performed. If not, the conversion sensitivity will be low. As shown in FIG. 4, for example, when the depth D of the valley has a depth equal to or higher than the ratio A to the height H of the mountain, a pulse is generated. The magnitude of this ratio A is the sensitivity. For example, when the ratio A is 5/16 or 8/16 with respect to the height H of the mountain, the sensitivity is higher when the ratio A is 5/16. That is, when the ratio A is 5/16, a pulse is generated if the valley depth D is 5/16 of the peak height H, but when the ratio A is 8/16, the valley If the depth D is not greater than 8/16 of the height H of the mountain, no pulse is generated.

  In the present embodiment, the high sensitivity pulse generator 5 performs pulse conversion with the ratio A being 5/16, and the low sensitivity pulse generator 4 is pulse converted with the ratio A being 8/16. The ripple pulse generation unit 3 performs pulse conversion with an intermediate ratio between the two as a ratio A. Preferably, the ratio A (AN) in the ripple pulse generator 3 is set in advance, and a ratio A (AH) having a higher sensitivity than the ratio AN is used in the high-sensitivity pulse generator 5, and the ratio AN is higher than the ratio AN. Also, the low sensitivity ratio A (AL) is used in the low sensitivity pulse generator 4. In addition, the numerical value hung up in this embodiment is an illustration for facilitating understanding, and does not limit the present invention at all.

  The detection capability determination unit 7 is capable of detecting the rotational state of the DC motor M by the rotation detection unit 6 based on the number of pulses of the three types of pulses RP, MRP, and LRP generated by the three pulse generation units 3 to 5 (accuracy). ). For example, when the number of low-sensitivity pulses LRP within a predetermined determination period T is less than the number of ripple pulses RP, the detection capability determination unit 7 determines a decrease in the rotation state detection capability by the rotation detection unit 6. .

  5 to 7 show an example of the relationship between the motor current (output FO of the switched capacitor filter 1) and the three types of pulses RP, MRP, and LRP when the rotation detection capability of the rotation detector 6 decreases. It is a wave form diagram showing typically. FIG. 5 shows that there are many noise components on the low frequency side, for example, the cutoff frequency of the switched capacitor filter 1 is adjusted to the low frequency side, and the number of low sensitivity pulses LRP is the other two types of pulses RP and MRP. An example of a decrease from the number is shown. FIG. 6 shows an example in which the cut-off frequency of the switched capacitor filter 1 is further adjusted to the low frequency side, and the number of ripple pulses RP is reduced to be the same as the number of low sensitivity pulses LRP. . FIG. 7 shows an example in which the cutoff frequency of the switched capacitor filter 1 is further adjusted to the low frequency side and the number of low sensitivity pulses LRP is further reduced. That is, the case where the number of pulses of the high sensitivity pulse MRP is larger than that of the ripple pulse RP and the number of pulses of the low sensitivity pulse LRP is smaller than that of the ripple pulse RP is illustrated.

  In other words, FIG. 6 shows that there are many noise components on the high frequency side. For example, the number of high-sensitivity pulses MRP passes through the switched capacitor filter 1 and the number of the other two types of pulses RP and LRP. It can be said that the number is increasing. Further, FIG. 5 can be said to be an example in which high frequency noise further increases from FIG. 6 and the number of ripple pulses RP increases to be the same as the number of high sensitivity pulses MRP. FIG. 7 can be said to be an example where the high frequency noise further increases. However, here, FIG. 6 is “an example in which the number of ripple pulses RP is reduced and is the same as the number of low-sensitivity pulses LRP”, and FIG. 7 is “an even lower-sensitivity pulse LRP than the state of FIG. As an example of “decreased”, the description will be continued below.

  As described above, the number of generated ripple pulses RP, low-sensitivity pulses LRP, and high-sensitivity pulses MRP may differ. As long as at least the ripple pulse RP is output in synchronization with the rotation of the DC motor M, the rotation state can be detected by the rotation detector 6. However, the difference in the number of pulses of the three types of pulses indicates that the possibility that the ripple pulse RP is out of synchronization with the DC motor M is high. That is, it shows that the rotation detection unit 6 has a decrease in the detection ability of the rotation state. Based on the number of pulses of each pulse in a predetermined determination period T, the detection capability determination unit 7 determines whether or not the detection capability of the rotation detection unit 6 has decreased.

  As shown in FIGS. 5 and 6, the determination period T is set to overlap like the determination periods T1 and T2, and the number of pulses of each pulse in the period is counted. However, it is not limited to this form, and the number of pulses may be counted without overlapping.

  Hereinafter, the determination method of the detection capability determination unit 7 based on the difference in the number of pulses will be described. Here, as described above, an example will be described in which the state sequentially changes from FIG. 3 to the states of FIGS. 5, 6, and 7. This is the case, for example, when the noise component on the low frequency side gradually increases and the cutoff frequency of the switched capacitor filter 1 is adjusted to the low frequency side.

[# 1: MRP = RP = LRP]
It is determined that the number of pulses RP, MRP, and LRP output from the three pulse generation units 3 to 5 is the same, and the detection capability of the rotation detection unit 6 can be sufficiently exhibited. The influence of low-frequency noise is large, and pulse omission occurs in all three pulse generators 3-5, and conversely, the influence of high-frequency noise is large, and pulses increase in all three pulse generators 3-5. The possibility of doing this cannot be denied. However, such a state is rare, and before reaching such a state, a state appears in which the number of pulses of the three pulses RP, MRP, and LRP is unbalanced, and maintenance of the DC motor M, etc. It is likely that appropriate measures have been taken. Therefore, in the case of condition # 1 (MRP = RP = LRP), the detection capability determination unit 7 determines that the detection capability of the rotation detection unit 6 is normal.

[# 2: MRP = RP> LRP]
This is a case where the number of pulses of the high sensitivity pulse MRP and the ripple pulse RP is the same, but the number of pulses of the low sensitivity pulse LRP is smaller than that of the ripple pulse RP. In this case, there is a possibility that the cut-off frequency of the switched capacitor filter 1 is adjusted to the low frequency side because the influence of the low frequency noise is large. Such a state has a high possibility of accompanying aged deterioration such as wear of the brush of the DC motor M as described above, and is not naturally improved.

  At this time, the high-sensitivity pulse MRP and the ripple pulse RP have the same number of pulses, and the ripple pulse RP accurately indicates the rotation state of the DC motor M. However, since the number of low-sensitivity pulses LRP has decreased, the detection capability determination unit 7 determines that the rotation state detection capability of the rotation detection unit 6 has decreased. Alternatively, the detection capability determination unit 7 may determine that the detection capability of the rotation state by the rotation detection unit 6 tends to decrease.

  The rotation state detection device 10 includes a notification unit 11 that notifies the determination result by the detection capability determination unit 7, and the determination result is notified to the seat position control device (DC motor control device) 20. Moreover, you may notify with respect to other ECUs including ECU which controls the whole vehicle. For example, in order to display a warning on the instrument panel of the driver's seat, the ECU that controls the warning display may be notified. Moreover, you may alert | report to ECU which records diagnosis information.

  In addition, it is preferable that the seat position control device (DC motor control device) 20 that has received the detection result of the detection capability from the rotation state detection device 10 restricts the operation of the DC motor M based on the determination result. This restriction can be achieved by notifying passengers that the seat adjustment motor has deteriorated via the instrument panel, etc., or by prohibiting the drive of the seat adjustment motor. Includes disabling the function.

[# 3: MRP> RP = LRP]
In this case, it is considered that the cutoff frequency of the switched capacitor filter 1 is further adjusted to the low frequency side, and the number of ripple pulses RP is also reduced to be the same as the number of low sensitivity pulses LRP. In this case, the rotation of the DC motor M is most accurately indicated by the high-sensitivity pulse MRP, and the ripple pulse RP is not a pulse indicating the rotation state of the DC motor M. Therefore, the detection capability of the rotation detection unit 6 that detects the rotation state of the DC motor M based on the ripple pulse RP is impaired.

  On the other hand, as described above, the case of # 3 also appears when the noise on the high frequency side increases. In this case, the ripple pulse RP and the low sensitivity pulse LRP accurately indicate the rotation state of the DC motor M, and the high sensitivity pulse MRP is a mixture of pulses caused by noise. Therefore, the detection capability of the rotation detector 6 that detects the rotation state of the DC motor M based on the ripple pulse RP is not impaired. That is, although the difference due to the influence of noise on the high frequency side is different, as in the case of # 2 above, the rotation detection unit 6 can accurately rotate the DC motor M only by “the ability to detect the rotational state tends to decrease”. This is a state where the state can be detected.

  Thus, considering that different situations are possible, in the present embodiment, in the case of # 3, the detection capability determination unit 7 determines that the detection capability of the rotation detection unit 6 has decreased. do not do. High-frequency noise can be basically suppressed by the switched capacitor filter 1, and the cut-off frequency of the filter 1 is excessively adjusted to the low-frequency side in the rotation state detection device 10. Is a bigger problem. And since the imbalance of the number of pulses caused by the noise component on the low frequency side gradually progresses, the case # 2 appears before the case # 3 appears. In the case of # 2, the detection capability determination unit 7 determines a decrease in detection capability, and the determination result is notified. Therefore, based on the notification, there is a high possibility that maintenance or the like of the DC motor M will be performed, and the possibility of reaching the # 3 case is relatively low. Therefore, in the case of # 3, there is no problem even if the detection capability determination unit 7 does not determine that the detection capability of the rotation detection unit 6 has decreased.

  Further, in the case where the noise on the high frequency side increases, when the noise further increases, it is considered that the case of # 2 follows the case of # 3. That is, the high frequency noise increases, and the pulse due to the noise is mixed into the ripple pulse RP, and the number of pulses of the ripple pulse RP and the high sensitivity pulse MRP coincides. In this case, as described above, the detection capability determination unit 7 can determine that “the detection capability has decreased”. Therefore, when the detection capability of the rotation detection unit 6 is impaired due to an increase in noise on the high frequency side, the determination by the detection capability determination unit 7 is appropriately performed.

[# 4: MRP>RP> LRP]
The case of # 4 is a case where the number of pulses of the high sensitivity pulse MRP is larger than that of the ripple pulse RP and the number of pulses of the low sensitivity pulse LRP is smaller than that of the ripple pulse RP. This case can be reached both when the influence of noise on the low frequency side becomes large and when the influence of noise on the high frequency side becomes large. In this case, it is difficult to accurately identify which of the high sensitivity pulse MRP, the ripple pulse RP, and the low sensitivity pulse LRP indicates the rotational state of the DC motor M. Therefore, the detection capability determination unit 7 determines that the rotation state detection capability of the rotation detection unit 6 is not normal.

  As described above, the three pulse generation units 3 to 5 are provided, and the ripples are compared by comparing the number of pulses of the three types of pulses RP, MRP, and LRP generated by the respective pulse generation units 3 to 5. The accuracy of the pulse RP can be determined. And the detection capability of the rotation detection part 6 which detects the rotation state of the DC motor M based on the ripple pulse RP can be determined.

  In the above embodiment, an example in which the detection capability of the rotation state of the rotation detector 6 is determined based on the states of the three types of pulses RP, MRP, and LRP has been described. However, the ripple pulse RP and the low sensitivity pulse LRP are illustrated. The rotation detection capability of the rotation detector 6 may be determined based on the two types of pulse states. When there is no high possibility that the influence of high-frequency noise will be excessive, and when there is a high possibility that the influence of noise on the low-frequency side will be excessive, there are two types of pulses: ripple pulse RP and low-sensitivity pulse LRP. The determination may be made based on the state. For example, in the case # 3, a decrease in detection capability is not determined. In both case # 2 and case # 4, since the determination condition is that the condition of RP> LRP is satisfied, it is possible to determine a decrease in detection capability without using the high-sensitivity pulse MRP. On the other hand, if the influence of noise on the low frequency side is not likely to be excessive, and if the influence of noise on the high frequency side is likely to be excessive, the ripple pulse RP and the high-sensitivity pulse MRP 2 Obviously, the determination may be made based on the state of the type of pulse.

[Second Embodiment]
In the embodiment described above, an example in which the rotation state detection capability of the rotation detection unit 6 is determined based on the states of the three types of pulses RP, MRP, and LRP at the time of determination has been described. However, the rotation state detection apparatus 10 may include a storage unit (not shown), store the determination result by the detection capability determination unit 7 as a determination history, and add this determination history to the determination condition. That is, the detection capability determination unit 7 may determine a decrease in the rotation state detection capability by the rotation detection unit 6 based on the ripple pulse RP, the low sensitivity pulse LRP, the high sensitivity pulse MRP, and the determination history. This embodiment will be described below.

  When the influence of noise on the low frequency side becomes excessive and the detection capability of the rotation detector 6 decreases, as described above, the transition is made in the order of the case # 1 to # 2, # 3, and # 4. Can be considered.

  Here, considering the case # 2, since the state before reaching the case # 2 is the case # 1, the detection capability determination unit 7 does not determine a decrease in the detection capability of the rotation detection unit 6. Therefore, a determination result indicating a decrease in detection capability is not stored in the storage unit. Here, as described above, the detection capability determination unit 7 has the same number of pulses of the high sensitivity pulse MRP as the number of pulses of the ripple pulse RP, and the number of pulses of the low sensitivity pulse LRP determines the number of pulses of the ripple pulse RP. When it falls below, it determines with the detection ability of the rotation state by a rotation detection part being in the fall tendency as 1st determination. The result of the first determination is stored in the storage unit.

  Even after the result of the first determination is stored, the state of the normal case # 2 continues. Therefore, even if the first determination result is stored in the storage unit, the detection capability determination unit 7 has the same number of pulses of the high sensitivity pulse MRP as the number of pulses of the ripple pulse RP, and the number of pulses of the low sensitivity pulse LRP. Is smaller than the number of pulses of the ripple pulse RP, it is determined as a first determination that the detection ability of the rotation state by the rotation detection unit 6 tends to decrease. Similarly, the result of the first determination is stored in the storage unit. Such a determination is continued while in the state of case # 2.

  When the transition from case # 2 to case # 3 is made, the number of high-sensitivity pulses MRP exceeds the number of ripple pulses RP, and the number of low-sensitivity pulses LRP is the same as the number of ripple pulses RP. Become. Here, when the first determination result is stored in the storage unit, the detection capability determination unit 7 determines that the detection capability of the rotation state of the rotation detection unit 6 is not normal as the second determination.

  On the other hand, when the influence of noise on the high frequency side becomes excessive and the detection capability of the rotation detector 6 decreases, as described above, the transition is made from the case # 1 to # 3, # 2, and # 4 in this order. It is possible.

  Here, considering case # 3 again, since the state before reaching case # 3 is case # 1, the detection capability determination unit 7 does not determine a decrease in the detection capability of the rotation detection unit 6. Therefore, a determination result indicating a decrease in detection capability is not stored in the storage unit. Here, as described above, the detection capability determination unit 7 has the same number of pulses of the low sensitivity pulse LRP as the number of pulses of the ripple pulse RP, and the number of pulses of the high sensitivity pulse MRP determines the number of pulses of the ripple pulse RP. When exceeding, it determines with the detection capability of the rotation state by the rotation detection part 6 having a tendency to fall as 3rd determination. The result of the third determination is stored in the storage unit.

  Even after the result of the third determination is stored, the state of case # 3 usually continues. Therefore, even if the third determination result is stored in the storage unit, the detection capability determination unit 7 has the same number of pulses of the low sensitivity pulse LRP as the number of pulses of the ripple pulse RP, and the number of pulses of the high sensitivity pulse MRP. Is greater than the number of pulses of the ripple pulse RP, it is determined as a third determination that the detection ability of the rotation state by the rotation detector tends to decrease. Similarly, the result of the third determination is stored in the storage unit. Such a determination is continued while in the state of case # 3.

  When a transition is made from the case # 3 state to the case # 2 state, the number of low-sensitivity pulses LRP is less than the number of ripple pulses RP, and the number of high-sensitivity pulses MRP is the same as the number of ripple pulses RP. Become. Here, when the third determination result is stored in the storage unit, the detection capability determination unit 7 determines that the rotation state detection capability of the rotation detection unit 6 is not normal as the fourth determination.

  Except for the determination history reference method, the determination criteria for comparing the number of three types of pulses are common to the first determination and the fourth determination, and the second determination and the third determination are common. Conversely, even if the determination criteria for comparing the number of three types of pulses are the same, the final determination result differs depending on the determination history. For example, if the result of the third determination is stored, the fourth determination is made even if the comparison result of the number of pulses is the same, and if the result of the third determination is not stored, the first determination is made. Further, if the result of the first determination is stored, the second determination is made even if the comparison result of the number of pulses is the same, and if the result of the first determination is not stored, the third determination is made.

  Therefore, precisely, the detection capability determination unit 7 does not store the result of the third determination in the storage unit, the number of pulses of the high sensitivity pulse MRP is the same as the number of pulses of the ripple pulse RP, and the low sensitivity When the number of pulses of the pulse LRP is less than the number of pulses of the ripple pulse RP, it is determined as a first determination that the rotation state detection capability by the rotation detector tends to decrease. The result of the first determination is stored in the storage unit.

  More precisely, if the result of the first determination is not stored in the storage unit, the detection capability determination unit 7 has the same number of pulses of the low-sensitivity pulse LRP as the pulse number of the ripple pulse RP. When the pulse number of the pulse MRP exceeds the pulse number of the ripple pulse RP, it is determined as a third determination that the rotation state detection capability by the rotation detection unit tends to decrease. The result of the third determination is stored in the storage unit.

  When the determination result of the detection capability determination unit 7 is the first determination or the third determination, the ripple pulse generation unit 3 generates a ripple pulse RP corresponding to the rotation of the DC motor M. Accordingly, a notification that prompts maintenance of the DC motor M is performed via the notification unit 11 or the motor control device 20. When the determination result of the detection capability determination unit 7 is the second determination or the fourth determination, the ripple pulse generation unit 3 cannot generate the ripple pulse RP corresponding to the rotation of the DC motor M. Accordingly, the seat position control device (motor control device) 20 restricts driving of the DC motor M, and preferably prohibits driving. Of course, even in the case of the first determination or the third determination, it does not prevent the drive of the DC motor M from being limited.

  Here, further, as the fifth determination, the detection capability determination unit 7 determines that the number of high-sensitivity pulses MRP in the determination period exceeds the number of ripple pulses RP in the determination period regardless of the determination history. When the number of low-sensitivity pulses LRP is less than the number of ripple pulses RP, it may be determined that the rotation state detection capability of the rotation detector 6 is not normal. Then, it is preferable that the seat position control device (motor control device) 20 notified of the determination result restricts or prohibits the driving of the DC motor M.

  As described above, according to the present invention, the rotation of the DC motor that can detect the rotation state of the DC motor using the ripple pulse and determine the detection capability of the rotation state using the ripple pulse. A state detection device can be provided.

Block diagram schematically showing the overall configuration of the seat position control device Block diagram schematically showing the configuration of a DC motor rotation state detection device Waveform diagram schematically showing an example of the relationship between the motor current and three pulse waveforms during normal operation Explanatory diagram showing the principle of pulse conversion Waveform diagram schematically showing an example of the relationship between the motor current and the three pulse waveforms when the detection capability is reduced Waveform diagram schematically showing an example of the relationship between the motor current and the three pulse waveforms when the detection capability is reduced Waveform diagram schematically showing an example of the relationship between the motor current and the three pulse waveforms when the detection capability is reduced

Explanation of symbols

1: Fitched capacitor filter (filter)
3: ripple pulse generation unit 4: low sensitivity pulse generation unit 5: high sensitivity pulse generation unit 6: rotation detection unit 7: detection capability determination unit 9: calculation unit 10: rotation state detection device 11: notification unit 20: control device FO : Motor current detection signals M, 39, 40, 41, 42 after passing through the filter: DC motor RP: ripple pulse LRP: low sensitivity pulse MRP: high sensitivity pulse

Claims (7)

A rotational state detection device for a direct current motor that detects the rotational state of the direct current motor based on a ripple component included in the motor current of the direct current motor,
A filter that removes a high-frequency noise component from the motor current detection signal;
The ripple pulse is converted into a pulse waveform based on the depth of the valley of the ripple component included in the detection signal of the motor current after passing through the filter and the ratio set to the height of the peak of the ripple component. A ripple pulse generator for generating
A calculation unit that calculates a cutoff frequency of the filter based on the detection signal of the motor current and the ripple pulse, and sets the cutoff frequency in the filter;
A low-sensitivity pulse that generates a low-sensitivity pulse by converting the ripple component into a pulse waveform based on a ratio larger than the ratio used when the ripple pulse generator converts the pulse waveform into a pulse waveform and the valley depth of the ripple component. A sensitivity pulse generator,
A rotation detector that detects a rotation state of the DC motor based on the ripple pulse;
A detection capability determination unit that determines a decrease in the detection capability of the rotation state by the rotation detection unit when the number of pulses of the low sensitivity pulse within a predetermined determination period is less than the number of pulses of the ripple pulse. Rotation state detection device.   The DC motor rotation state detection device according to claim 1, further comprising a notification unit that notifies a decrease in rotation state detection capability by the rotation detection unit based on a determination result of the detection capability determination unit. A high-sensitivity pulse is generated by converting the ripple component into a pulse waveform based on a ratio smaller than the ratio used when the ripple pulse generation unit converts the pulse waveform into a pulse waveform and the valley depth of the ripple component. With a sensitivity pulse generator,
In the detection capability determination unit, the number of high-sensitivity pulses in the determination period exceeds the number of ripple pulses, and the number of low-sensitivity pulses in the determination period is less than the number of ripple pulses. 3. The DC motor rotation state detection device according to claim 1, wherein the rotation detection unit determines that the rotation state detection capability is not normal. A high-sensitivity pulse is generated by converting the ripple component into a pulse waveform based on a ratio smaller than the ratio used when the ripple pulse generation unit converts the pulse waveform into a pulse waveform and the valley depth of the ripple pulse. A sensitivity pulse generator,
A storage unit that stores a determination result by the detection capability determination unit as a determination history,
The detection capability determination unit, based on the ripple pulse, the low sensitivity pulse, the high sensitivity pulse, and the determination history, a decrease in the detection capability of the rotation state by the rotation detection unit, a first determination, a second determination, The determination is performed by distinguishing at least four of the third determination and the fourth determination.
The third determination is not stored as the determination history, the number of pulses of the high sensitivity pulse in the determination period is the same as the number of pulses of the ripple pulse, and the pulse of the low sensitivity pulse in the determination period When the number is less than the number of pulses of the ripple pulse, it is determined that the detection ability of the rotation state by the rotation detection unit tends to decrease as the first determination,
The first determination is stored as the determination history, the number of high-sensitivity pulses in the determination period exceeds the number of ripple pulses, and the number of low-sensitivity pulses in the determination period is When the number of ripple pulses is the same, it is determined that the rotation state detection capability by the rotation detection unit is not normal as the second determination,
The first determination is not stored as the determination history, the number of pulses of the low sensitivity pulse in the determination period is the same as the number of pulses of the ripple pulse, and the pulse of the high sensitivity pulse in the determination period When the number exceeds the number of pulses of the ripple pulse, as the third determination, it is determined that the detection capability of the rotation state by the rotation detection unit tends to decrease,
The third determination is stored as the determination history, the number of pulses of the low sensitivity pulse in the determination period is less than the number of pulses of the ripple pulse, and the number of pulses of the high sensitivity pulse in the determination period is 3. The DC motor rotation state detection device according to claim 1, wherein when the number of ripple pulses is the same as the number of ripple pulses, the rotation determination unit determines that the rotation state detection capability is not normal as the fourth determination. A DC motor control device comprising the DC motor rotation state detection device according to any one of claims 1 to 4,
A DC motor control device that restricts driving of the DC motor based on a determination result of the detection capability determination unit. A DC motor control device comprising the DC motor rotation state detection device according to claim 4,
When the determination result of the detection capability determination unit is the first determination or the third determination, a notification that prompts maintenance of the DC motor is performed,
When the determination result of the detection capability determination unit is the second determination or the fourth determination, the DC motor control device prohibits the driving of the DC motor. The depth of the valley of the ripple component is the maximum amplitude value within a plurality of periods of the ripple component, and the height of the peak of the ripple component is the maximum amplitude value from the peak value side within one period of the ripple component. And the ratio is set on the basis of the peak value side, the rotational state detection device for a DC motor according to any one of claims 1 to 4.

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