JP2012215443A - Rotation direction detector and rotation direction detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation direction detector and a rotation direction detection method capable of accurately detecting a rotation direction of a rotor provided in a power generation part by self power generation.SOLUTION: A rotation direction detector 1 comprises: a power generation part 2 which has a stator and a rotor and generates an AC voltage by the rotation of the rotor relative to the stator; rotation means 3 which rotates the rotor in a first direction or a second direction opposite to the first direction relative to the stator; and a detection part 7 which is driven by the voltage generated from the power generation part 2 and detects the rotation direction of the rotor. The detection part 7 detects a voltage value of the power generated from the power generation part 2 at the time after the lapse of a prescribed time from the time of starting the drive, and detects the rotation direction of the rotor relative to the stator on the basis of the size of the detected voltage value.

Description

  The present invention relates to a rotation direction detection device and a rotation direction detection method.

  As a generator used in the field of energy harvesting, for example, it has a stator (stator) and a rotor (rotor), and the rotor is rotated with respect to the stator by external force, thereby generating electric power. A motor-type generator may be used. When such a generator is used, it is desirable that the rotation direction of the rotor relative to the stator can be detected.

  Patent Document 1 discloses a motor rotation direction detection device that detects the rotation direction of a motor. The apparatus described in Patent Document 1 is configured to attach an angular velocity sensor and a magnetic sensor to a housing of a motor and detect the rotation direction of the motor (rotor) based on the detection results of these two sensors. .

  In such a device, for example, it is possible to detect the rotation direction of the rotor using the electric power generated by using the motor as the power generation unit, rotating the rotor with an external force, and the generated electric power. However, such a configuration causes the following problems.

  That is, the various sensors included in the device of Patent Document 1 have a long time (start-up time) from when power is supplied to when they are in a standby state (a state in which a physical quantity can be detected). It cannot be detected. In particular, in the field of energy harvesting, since the rotor rotates for a very short time (for example, several tens of milliseconds), when the sensor as described above is used, the rotation direction can be detected. Sometimes, it is considered that the rotation of the rotor has already stopped and the rotation direction of the rotor cannot be detected.

JP 2004-251755 A

  The objective of this invention is providing the rotation direction detection apparatus and rotation direction detection method which can detect correctly the rotation direction of the rotor which an electric power generation part has by self-power generation.

Such an object is achieved by the present inventions (1) to (9) below.
(1) a power generation unit that includes a stator and a rotor that is rotatable with respect to the stator, and generates an AC voltage by rotating the rotor with respect to the stator;
Rotating means for rotating the rotor relative to the stator in a first direction or a second direction opposite to the first direction;
Driven by the voltage generated from the power generation unit, and having a detection unit for detecting the rotation direction of the rotor relative to the stator,
The detection unit detects a voltage value of electric power generated from the power generation unit at a time when a predetermined time has elapsed from a time when the driving is started, and based on the detected voltage value, the rotation with respect to the stator A rotation direction detecting device for detecting a rotation direction of a child.

  (2) A first voltage generated from the power generation unit when the rotor rotates in the first direction with respect to the stator, and the rotor rotates in the second direction with respect to the stator. In the above (1), the second voltage generated from the power generation unit is configured such that the peak generation timing is different with respect to the time when the rotor starts rotating with respect to the stator. The rotation direction detecting device described.

  (3) The detection unit detects the voltage value at a time when a peak occurs from one of the first voltage and the second voltage and a peak does not occur from the other. (1) Or the rotation direction detection apparatus as described in (2).

  (4) The detection unit detects the rotation direction of the rotor relative to the stator based on whether the detected voltage is larger or smaller than a predetermined threshold. The rotation direction detection device according to any one of the above.

  (5) The rotating means may rotate the rotor in the first direction or the second direction with respect to the stator in the first direction or the second direction at the same rotation angle and rotation speed each time. The rotation direction detecting device described.

  (6) The rotating means is configured such that the rotation speed of the rotor is equal when rotating the rotor in the first direction relative to the stator and when rotating the rotor in the second direction. The rotational direction detection device according to any one of (1) to (5).

  (7) The rotating means is configured such that the rotation angle of the rotor is equal when rotating the rotor in the first direction relative to the stator and when rotating the rotor in the second direction. The rotational direction detection device according to any one of (1) to (6).

  (8) The rotating means includes a switch that can be switched between a first state and a second state. When the switch is switched from the first state to the second state, the rotor moves with respect to the stator. (1) to (7), wherein the rotor is configured to rotate in the first direction and to rotate in the second direction with respect to the stator when the second state is switched to the first state. The rotation direction detection device according to any one of the above.

(9) having a rotor that can rotate in a first direction or a second direction opposite to the first direction with respect to the stator, and the rotor rotates with respect to the stator; A rotation direction detection method for detecting a rotation direction of the rotor relative to the stator of a power generation unit that generates an alternating voltage by a detection unit,
The detection unit is driven by a voltage generated from the power generation unit, detects a voltage value of electric power generated from the power generation unit at a time when a predetermined time has elapsed from a time when the drive is started, and a magnitude of the detected voltage value And detecting a direction of rotation of the rotor relative to the stator based on the height.

  According to the rotation direction detection device and the rotation direction detection method according to the present invention, the detection unit is quickly activated by the electric power generated from the power generation unit, so that the rotation direction of the rotor can be accurately detected. Moreover, since an external power supply is not required, it becomes an environment-friendly device (method).

  Further, since the rotation direction is detected based on the magnitude of the voltage generated by the power generation unit at a predetermined time, the rotation direction of the rotor can be detected with high accuracy. In particular, the first voltage and the second voltage have different pulse generation timings based on the time at which the rotor starts rotating with respect to the stator, so that the first voltage and the second voltage at a predetermined time are different from each other. Can be increased, and the detection accuracy can be increased.

  The rotating means rotates the rotor in the first direction with respect to the stator at the same rotation angle and rotation speed each time, and rotates the rotor in the second direction with respect to the stator at the same rotation angle and rotation speed each time. If it is comprised so that the waveform of a 1st voltage and a 2nd voltage can be made into the substantially same waveform each time, the reliability of a detection improves.

  Further, by rotating the rotor in response to the operation of the switch, the rotation direction detecting device can be used as various switches, and the convenience is improved.

It is a block diagram which shows the structure of the rotation direction detection apparatus of this invention. It is a top view which shows the specific structure of the rotation means shown in FIG. It is a figure which shows the voltage which generate | occur | produces from the electric power generation part shown in FIG.

  Hereinafter, preferred embodiments of a rotation direction detection device and a rotation direction detection method of the present invention will be described with reference to the accompanying drawings. Hereinafter, a case where a transmitter is configured using the rotation direction detection device of the present invention will be described.

  FIG. 1 is a block diagram showing the configuration of the rotation direction detecting device of the present invention, FIG. 2 is a plan view showing the specific configuration of the rotating means shown in FIG. 1, and FIG. 3 is generated from the power generation unit shown in FIG. It is a figure which shows the voltage to carry out.

  A transmitter (rotation direction detection device) 1 shown in FIG. 1 is an energy self-contained device that wirelessly transmits a predetermined signal to an external device. The transmitter 1 mainly includes a power generation unit 2, a rotating unit 3, a rectification unit (rectification circuit) 4, a power storage unit 5, a transformation unit 6, a detection unit (main circuit) 7, and a discharge unit 8. And an RF controller 9 and an antenna 10.

Hereinafter, these will be described in detail sequentially.
-Power generation section-
As shown in FIG. 2, the power generation unit 2 is accommodated in the housing 100. The power generation unit 2 can generate AC power (AC voltage) by self-power generation. For example, the power generation unit 2 can generate the power when a force (physical force, magnetic force, etc.) is applied from the outside. it can. Therefore, the power generation unit 2 generates power temporarily (temporarily) rather than continuously. By using the power generation unit 2, the transmitter 1 can be reduced in size, and environmentally friendly power generation (environmental power generation) is possible.

  The power generation unit 2 includes a stator (not shown) and a rotor (rotor) (not shown) that can rotate with respect to the stator, and the rotor is rotated with respect to the stator by an external force. To generate electricity. As such a power generation part 2, various motors, such as a stepping motor and a DC motor, can be used, for example.

  Although the electric power generation amount of 1 time of the electric power generation part 2 is not specifically limited, It is preferable that it is about 500-1500microJ / 5-20msec.

-Rotating means 3-
The rotating means 3 has a function of rotating the rotor of the power generation unit 2 with respect to the stator. As shown in FIG. 2, the rotating means 3 has a switch 31 provided in the housing 100, and when the switch 31 is operated, the rotor of the power generation unit 2 correspondingly moves with respect to the stator. Rotate. That is, electric power is generated from the power generation unit 2 by operating the switch 31.

  As shown in FIG. 2, the switch 31 includes, for example, two pressing portions 311 and 312, and is in an ON state (state indicated by a solid line in FIG. 2; first state) in which the pressing portion 311 is pushed into the housing 100 side. State) and an OFF state (state indicated by a chain line in FIG. 2; second state) in which the pressing portion 312 is pushed into the housing 100 can be switched.

  When the switch 31 is operated from the OFF state to the ON state, the rotor of the power generation unit 2 temporarily rotates forward (for example, clockwise in FIG. 2; first direction) with respect to the stator. To do. On the contrary, when the switch 31 is operated from the ON state to the OFF state, the rotor of the power generation unit 2 is temporarily moved in the reverse direction (for example, counterclockwise in FIG. 2; second direction) with respect to the stator. Rotate to.

  Thus, in the transmitter 1, since the rotation direction of the rotor differs depending on whether the switch 31 is switched from the ON state or the OFF state, by detecting the rotation direction of the rotor, It is possible to detect the state of the switch 31, that is, whether it is in an ON state or an OFF state.

  The mechanism for rotating the rotor with respect to the stator by operating the switch 31 is not particularly limited. For example, the following mechanism can be used. For example, two spring members (a first spring member and a second spring member) that are installed in the housing 100 and are directly or indirectly connected to the rotor are prepared. The first spring member is for rotating the rotor in the forward direction, and the second spring member is for rotating the rotor in the reverse direction.

  Then, the first spring member is extended by using the displacement of the switch 31 when the switch is switched from the OFF state to the ON state (change in the posture of the switch 31 with respect to the housing 100). The first spring member is contracted by releasing the extension, and the rotor is rotated in the forward direction with respect to the stator by using the contraction force. On the contrary, the second spring member is extended by using the displacement of the switch 31 when switching from the ON state to the OFF state, and the second spring member is released by releasing the extension at the same time as the switch 31 is turned OFF. The rotor is contracted, and the rotor is rotated in the opposite direction with respect to the stator by using the contraction force.

  According to such a mechanism, the rotor can be rotated with respect to the stator by operating the switch 31 with a simple configuration. Further, since such a mechanism is a physical mechanism, it is possible to effectively prevent malfunctions and the like.

  Further, with such a configuration, the rotational speed and the rotational angle of the rotor with respect to the stator can be reduced without being affected by the operation of the switch 31 (the displacement speed of the switch 31 or the force applied to the switch 31). It can be kept almost constant every time. That is, the rotating means 3 is configured to be able to rotate the rotor in the forward direction or the reverse direction with respect to the stator at the same rotation angle and rotation speed each time.

  By adopting such a configuration, the first voltage generated from the power generation unit 2 when the rotor rotates in the forward direction can be set to substantially the same waveform (including timing (phase)) each time, and similarly In addition, the second voltage generated from the power generation unit 2 when the rotor rotates in the reverse direction can be set to substantially the same waveform (including timing (phase)) each time. Therefore, the rotation direction of the rotor can be detected more accurately by a method described later.

  The rotating means 3 rotates the rotor with respect to the stator in the forward direction and rotates in the reverse direction with respect to the stator, and the rotational angle and rotational speed of the rotor with respect to the stator (average rotational speed; average angular speed). Are configured to be equal to each other. Thereby, the operating condition (power generation condition) of the power generation unit 2 can be made equal between the case where the rotor rotates in the forward direction and the case where the rotor rotates in the reverse direction. Therefore, the rotation direction of the rotor with respect to the stator can be detected more accurately by a method described later.

  In the case where the mechanism of the rotating means 3 is configured to use the first spring member and the second spring member as described above, for example, the configuration (shape, size, elasticity of the first spring member and the second spring member). If the first spring member and the second spring member are stretched to be equal to each other, the rotor can be easily forward and forward relative to the stator. Both the rotation angle and the rotation speed of the rotor can be made equal when rotating in the reverse direction and when rotating in the opposite direction.

-Rectifier 4-
The rectification unit (rectification circuit) 4 is connected to the power generation unit 2. The rectification unit 4 has a function of rectifying AC power generated by the power generation unit 2 into DC power. The configuration of the rectification unit 4 is not particularly limited as long as such a function can be exhibited, and a known rectification circuit can be used.

-Power storage unit 5-
The power storage unit 5 is connected to the rectification unit 4. The power storage unit 5 is configured with, for example, a capacitor or the like, and can store power of a predetermined capacity. Thereby, the electric power generated by the power generation unit 2 can be stored, and the electric power can be stably supplied to the detection unit 7 and the RF controller 9 as described later. Although it does not specifically limit as a capacity | capacitance of the electrical storage part 5, It can be set as about 50-80microF.

-Transformer 6
Transformer unit (DC / DC converter) 6 is connected to rectifier unit 4 and power storage unit 5, respectively. The transformer 6 has a function of adjusting the DC voltage input from the rectifier 4 to a predetermined voltage value. The DC voltage output from such a transformer 6 is supplied to the detector 7 and the RF controller 9, whereby the detector 7 and the RF controller 9 are operated. The voltage value to be adjusted by the transformer 6 is not particularly limited, but is about 2 to 3V.

-Detector 7-
The detection unit 7 is configured by, for example, a microcontroller (microcomputer). The detection unit 7 is connected to the transformer 6 and is driven by the electric power generated by the power generation unit 2 and adjusted by the transformer 6. The alternating voltage generated from the power generation unit 2 is directly input to the detection unit 7 as an analog signal. And the detection part 7 detects the rotation direction of the rotor with respect to a stator based on the input alternating voltage.

Hereinafter, detection of the rotation direction of the rotor by the detection unit 7 will be described.
FIG. 3A shows a voltage (first voltage) V1 generated from the power generation unit 2 when the rotor rotates in the forward direction with respect to the stator, and is rectified by the rectification unit 4. The voltage V1 ′ is shown. Further, FIG. 6B shows that a voltage (second voltage) V2 generated by the power generation unit 2 when the rotor rotates in the reverse direction with respect to the stator and input to the detection unit 7 is generated by the rectification unit 4. The rectified voltage V2 ′ is shown.

  Note that the voltages V1 and V2 shown in FIGS. 3A and 3B are examples, and the waveforms of the voltages V1 and V2 are not limited thereto.

  As shown in FIG. 3, when viewed from time T0 when the rotor starts rotating with respect to the stator, first, the first peak P1 of the voltage V1 occurs, and then the voltage A first peak P2 of V2 occurs, then a second peak P3 of voltage V1 occurs, and then a second peak P4 of voltage V2 occurs. That is, the peak of the voltage V1 and the peak of the voltage V2 are alternately generated.

  As described above, the transmitter 1 is configured such that the generation timing of the peak is different between the voltage V1 and the voltage V2 with respect to the time T0 when the rotor starts rotating with respect to the stator. The difference between the voltages V1 and V2 can be increased at almost all times when the voltage is generated from the unit 2. Therefore, the rotation direction of the rotor relative to the stator can be detected more accurately and reliably by the method described later.

  As described above, in the present embodiment, the rotation speed and the rotation angle of the rotor with respect to the stator can be kept substantially constant each time without being affected by how the switch 31 is operated. Therefore, every time the switch 31 is switched from OFF to ON, a voltage V1 having substantially the same waveform as that in FIG. 3A is generated, and every time that the switch 31 is switched from ON to OFF, a voltage having approximately the same waveform as in FIG. V2 is generated.

  The detection unit 7 detects the voltage value of the electric power generated from the power generation unit 2 at a time T2 when a predetermined time has elapsed from the time T1 when the driving is started, and rotates the stator with respect to the magnitude of the detected voltage value. Detect the rotation direction of the child. The detection of the voltage value can be performed using a voltage input as an analog signal from the power generation unit 2 (that is, a voltage that has not been rectified by the rectification unit 4). The detection unit 7 may include a clock oscillation unit such as a crystal oscillator in order to determine the time T2.

  As shown in FIG. 3, the voltages V1 'and V2' after rectification by the rectifier 4 have substantially the same waveform. Therefore, the detection unit 7 starts driving at time T1 regardless of the rotation direction of the rotor. That is, the time from when the rotor starts to rotate until the detector 7 starts driving is almost the same every time regardless of the direction of rotation of the rotor. Therefore, the detection unit 7 detects the magnitude of the voltage at time T2 when a predetermined time has elapsed from the time T0 when the rotor starts to rotate, and detects the rotation direction of the rotor based on the detected magnitude of the voltage. I can say.

  The time T2 is preferably a time when the difference between the voltages V1 and V2 is large. Specifically, as shown in FIG. 3, the time T2 is preferably a time at which a peak occurs at one of the voltages V1 and V2 and a peak does not substantially occur at the other. As a result, the difference between the voltages V1 and V2 can be increased, and the rotation direction of the rotor can be accurately detected.

  In the following, for convenience of explanation, the case where the time T2 is a time when a peak occurs in the voltage V1 and no peak occurs in the voltage V2 will be described as a representative.

  The time T2 is not particularly limited, but is preferably a time after 0.1 to 0.3 msec from the time T1 when the driving of the detection unit 7 starts. In general, since the voltage generated from the power generation unit 2 by the operation of the switch 31 is about several tens of msec, the voltage generated from the power generation unit 2 can be surely set by setting the time T2 as described above. Can be detected. Further, by setting the time as described above, the maximum value of the peak becomes sufficiently large, and the difference between the voltages V1 and V2 can be sufficiently increased. Therefore, the detection accuracy of the rotation direction of the rotor can be further increased.

  Moreover, the detection part 7 may detect the magnitude | size of a voltage instantaneously in the time T2, and may detect the magnitude | size of a voltage within the predetermined time from the time T2. In the latter case, the magnitude of the voltage within a predetermined period can be averaged, and the rotation direction of the rotor can be detected based on the average value. In addition, as said predetermined time, it is preferable that it is about 1-2 msec, for example.

  A threshold value is set in the detection unit 7 in advance. This threshold value is not particularly limited as long as it is set larger than the voltage V2 at time T2 and smaller than the voltage V1 at time T2, but it is preferable to set the threshold to a value about the intermediate value of these voltages. . Thereby, the rotation direction of the rotor can be detected more accurately.

  The detection unit 7 detects the rotation direction of the rotor based on whether the magnitude of the voltage at time T2 is larger or smaller than the threshold value Vt. Specifically, if the magnitude of the voltage input at time T2 is larger than the threshold value Vt, the detection unit 7 rotates the rotor in the forward direction with respect to the stator, and the switch 31 changes from the OFF state to the ON state. If the magnitude of the input voltage is smaller than the threshold value Vt, it is detected that the rotor rotates in the reverse direction with respect to the stator and the switch 31 is changed from the ON state to the OFF state. To do.

  Thus, by comparing with the preset threshold value Vt, it is possible to detect the rotation direction of the rotor more accurately. The threshold value Vt can be stored in a storage unit (not shown) of the detection unit 7, for example. The threshold value Vt can be easily set to an optimal value by simulation or experiment.

  Here, the difference between the voltage value of the voltage V1 and the voltage value of the voltage V2 at time T2 is not particularly limited, but is preferably about 0.5 to 2.0V. Thereby, the difference between the voltages V1 and V2 becomes sufficiently large, and the difference between the threshold value Vt and the voltage V1 and the difference between the threshold value Vt and the voltage V2 at time T2 can be sufficiently secured. Therefore, the rotation direction of the rotor can be detected more accurately.

  Since such a detection unit 7 is composed of a microcontroller, the start-up from the power supply is quick, and the time (start-up time) until the detection can be performed from the power supply is extremely long. Short, usually less than 1 msec. Here, since the waveforms of the voltages V1 and V2 as shown in FIGS. 3A and 3B usually appear as short as several tens of msec, the detection unit having a fast start-up time as in this embodiment. By using 7, the voltage input to the detection unit 7 and the threshold value Vt can be reliably compared, and the rotation direction of the rotor can be accurately detected. That is, according to the detection unit 7, it is possible to accurately detect the rotation direction of the rotor without supplying power from an external power source other than the power generation unit 2.

-RF controller 9-
The RF controller 9 is connected to the transformer 6 and the detector 7. Such an RF controller 9 is driven by the electric power supplied from the transformer 6, and, for example, a signal related to the rotation direction of the rotor detected by the detector 7 under the control of the detector 7 (a signal related to the state of the switch 31). Is oscillated as a signal having a predetermined frequency.

-Antenna 10-
An antenna 10 is connected to the RF controller 9, and the antenna 10 wirelessly transmits a signal oscillated by the RF controller 9 to an external device.

-Discharge unit 8-
Discharge unit 8 is connected to power storage unit 5 and detection unit 7. Such a discharge unit 8 discharges the electric power stored in the power storage unit 5 after finishing the transmission of the signal from the antenna 10 as described above and no more power supply is required. The discharge unit 8 may be provided as necessary. For example, when almost all of the electric power generated from the power generation unit 2 is used to drive the detection unit 7 and the RF controller 9, the discharge unit 8 may be omitted.

  The transmitter 1 has been described in detail above. According to such a transmitter 1, it is possible to accurately detect the rotation direction of the rotor without using an external power source or the like.

  As mentioned above, although the rotation direction detection apparatus and rotation direction detection method of this invention were demonstrated based on embodiment of illustration, this invention is not limited to this. For example, in the rotation direction detection device of the present invention, the configuration of each part can be replaced with any configuration that exhibits the same function, and any configuration can be added.

  In the above-described embodiment, the signal related to the rotation direction of the rotor is transmitted wirelessly, but may be transmitted by wire.

1. Rotation direction detector (transmitter)
2 ... Power generation section 3 ... Rotating means 31 ... Switches 311, 312 ... Press section 4 ... Rectification section 5 ... Power storage section 6 ... Transformer section 7 ... Detection section 8 ... Discharge section 9 ... RF Controller 10 ... Antenna 100 ... Case

Claims (9)

A power generator that has a stator and a rotor that is rotatable relative to the stator, and generates an alternating voltage by rotating the rotor relative to the stator;
Rotating means for rotating the rotor relative to the stator in a first direction or a second direction opposite to the first direction;
Driven by the voltage generated from the power generation unit, and having a detection unit for detecting the rotation direction of the rotor relative to the stator,
The detection unit detects a voltage value of electric power generated from the power generation unit at a time when a predetermined time has elapsed from a time when the driving is started, and based on the detected voltage value, the rotation with respect to the stator A rotation direction detecting device for detecting a rotation direction of a child.   The rotor rotates in the first direction relative to the stator, the first voltage generated from the power generation unit, and the rotor rotates in the second direction relative to the stator. 2. The rotation direction according to claim 1, wherein the second voltage generated from the power generation unit is configured to have different peak generation timings based on a time when the rotor starts rotating with respect to the stator. Detection device.   The said detection part detects the said voltage value in the time when the peak generate | occur | produces from one of the said 1st voltage and the said 2nd voltage, and the peak does not generate | occur | produce from the other. Rotation direction detection device.   The said detection part detects the rotation direction of the said rotor with respect to the said stator based on whether the magnitude | size of the detected said voltage is large or small with respect to a predetermined threshold value. Rotation direction detection device.   5. The rotation direction detection device according to claim 1, wherein the rotation unit rotates the rotor in the first direction or the second direction with respect to the stator at the same rotation angle and rotation speed each time. .   The rotating means is configured such that the rotation speed of the rotor is equal when rotating the rotor in the first direction relative to the stator and when rotating the rotor in the second direction. Item 6. The rotation direction detection device according to any one of Items 1 to 5.   The rotation means is configured so that the rotation angle of the rotor is equal when rotating the rotor in the first direction relative to the stator and when rotating the rotor in the second direction. Item 7. The rotational direction detection device according to any one of Items 1 to 6.   The rotating means has a switch that can be switched between a first state and a second state, and when the switch is switched from the first state to the second state, the rotor is in the first direction with respect to the stator. The rotation according to claim 1, wherein the rotor is configured to rotate in the second direction with respect to the stator when the second state is switched to the first state. Direction detection device. A stator and a rotor that is rotatable relative to the stator in a first direction or a second direction opposite to the first direction, and the rotor rotates relative to the stator to generate an alternating voltage; A rotation direction detection method for detecting a rotation direction of the rotor with respect to the stator of a power generation unit that is generated by a detection unit,
The detection unit is driven by a voltage generated from the power generation unit, detects a voltage value of electric power generated from the power generation unit at a time when a predetermined time has elapsed from a time when the drive is started, and a magnitude of the detected voltage value And detecting a direction of rotation of the rotor relative to the stator based on the height.

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