Patent Description:
In a wind turbine for wind power generation, the yaw control for turning the rotor and the nacelle of the wind turbine in accordance with the wind direction is performed to enhance the efficiency in rotation of the blades of the wind turbine. In the yaw control, for example, a driving force (i.e., a load) is transmitted from a drive device provided in the nacelle to a ring gear provided on the upper end portion in the tower, thereby causing the drive device to turn along with the nacelle.

To retain the nacelle at the position reached after the turning by the yaw control, the wind turbine is provided with an electromagnetic brake for braking the rotation of the drive shaft of the drive device, as disclosed in, for example, <CIT>.

Document <CIT> relates to a wind turbine drive control device for controlling a plurality of drive devices for moving two structures included in a wind power generation device relative to each other, the wind turbine drive control device including: an obtaining unit for obtaining a plurality of information items related to loads occurring between each of the plurality of drive devices and one of the two structures that receives forces generated by the plurality of drive devices; and a control unit for controlling the plurality of drive devices in such a manner that, in a state where each of the plurality of drive devices is controlled to generate a predetermined braking force, the braking force of at least one first drive device among the plurality of drive devices is increased, based on the plurality of information items.

Document <CIT> relates to a wind turbine comprising a nacelle with a generator and wind turbine blades for driving the generator, and a tower supporting the nacelle, and document <CIT> relates to a wind turbine comprising an active yaw system realised to maintain an upwind orientation of the wind turbine aerodynamic rotor during safe operating conditions.

The load acting from the drive device onto the ring gear may vary abruptly due to an abrupt change in the wind direction or the wind velocity. To inhibit damage of the ring gear due to an abrupt change in the load acting on the ring gear, the electromagnetic brake needs to be released quickly.

However, in the conventional arts, an electromagnetic contactor was used to open and close the electromagnetic brake, and therefore, it was difficult to release the electromagnetic brake instantly.

The present invention addresses the above drawback, and one object thereof is to provide a wind turbine brake control device and a wind turbine capable of inhibiting the damage of the ring gear of the wind turbine due to an abrupt change in the load acting on the ring gear.

The present invention is a wind turbine brake control device comprising: an electromagnetic brake for braking at least one of relative rotation between a pinion gear installed in a first structure and a ring gear installed in a second structure or rotation of a motor having the pinion gear mounted thereto, the first structure and the second structure constituting a movable section of a wind turbine; and a contactless relay disposed on a power supply line between a power supply for operation of the electromagnetic brake and the electromagnetic brake and configured to open and close the power supply line, wherein the power supply is a three-phase power supply, and the contactless relay is a three-phase relay or a single-phase.

The present invention is a wind turbine brake control device comprising: an electromagnetic brake for braking at least one of relative rotation between a pinion gear installed in a first structure and a ring gear installed in a second structure or rotation of a motor having the pinion gear mounted thereto, the first structure and the second structure constituting a movable section of a wind turbine; and a contactless relay configured to open and close a power supply line between a power supply for operation of the electromagnetic brake and the electromagnetic brake at a response speed of <NUM> or less.

In the wind turbine brake control device according to the present invention, the first structure may be a nacelle.

The wind turbine brake control device according to the present invention may further comprise a speed reducer connected to a rotating shaft of the motor and configured to decelerate the rotation of the motor and output motive power with an increased torque to the pinion gear, and the electromagnetic brake may brake rotation of the rotating shaft of the motor to brake rotation of the pinion gear.

The wind turbine brake control device according to the present invention may further comprise: a sensor for sensing a load acting between a drive device and the ring gear, the drive device including the motor, the speed reducer, and the pinion gear; and a control unit configured to output to the contactless relay a control signal for controlling opening and closing of the power supply line in accordance with the sensed load.

In the wind turbine brake control device according to the present invention, the sensor may be a strain sensor configured to sense the load by sensing a strain of a bolt fixing the drive device to the movable section, and when the sensed load exceeds a threshold value, the control unit may output a signal as the control signal for an instruction for opening or closing the power supply line.

In the wind turbine brake control device according to the present invention, the contactless relay may include a photocoupler.

In the wind turbine brake control device according to the present invention, the contactless relay may include a MOSFET.

The wind turbine brake control device according to the present invention may further comprise a surge protection element disposed on the power supply line between the contactless relay and the electromagnetic brake.

The present invention is a wind turbine comprising: a wind turbine brake control device, wherein the wind turbine brake control device includes: an electromagnetic brake for braking at least one of relative rotation between a pinion gear installed in a first structure and a ring gear installed in a second structure or rotation of a motor having the pinion gear mounted thereto, the first structure and the second structure constituting a movable section of the wind turbine; and a contactless relay disposed on a power supply line between a power supply for operation of the electromagnetic brake and the electromagnetic brake and configured to open and close the power supply line, wherein the power supply is a three-phase power supply, and the contactless relay is a three-phase relay or a single-phase.

The present invention makes it possible to inhibit damage of the ring gear of the wind turbine due to an abrupt change in the load acting on the ring gear.

The embodiments of the present invention will now be described with reference to the appended drawings. In the drawings, for ease of illustration and understanding, a scale size, a dimensional ratio, and so on are altered or exaggerated as appropriate from actual values.

<FIG> is a block diagram showing a wind turbine brake control device <NUM> according to a first embodiment. <FIG> is a perspective view showing a wind turbine <NUM> according to the first embodiment. <FIG> is a circuit diagram showing the wind turbine brake control device <NUM> according to the first embodiment.

The wind turbine brake control device <NUM> controls the braking of the wind turbine <NUM> performed by the electromagnetic brake <NUM> (described later). As shown in <FIG>, the wind turbine brake control device <NUM> includes an electromagnetic brake <NUM>, a contactless relay <NUM>, a control unit <NUM>, and a protection circuit <NUM>.

The electromagnetic brake <NUM> brakes the relative rotation between a pinion gear 24a installed in a first structure and a ring gear <NUM> installed in a second structure, the first structure and the second structure constituting a movable section of the wind turbine <NUM>. Additionally or alternatively, the electromagnetic brake <NUM> brakes the rotation of a motor <NUM> having the pinion gear 24a mounted thereto. The term "braking," which should be broadly construed, embraces both retaining a stopped state of an object that has been stopped and stopping a moving object.

As shown in <FIG>, the wind turbine <NUM> includes a tower <NUM>, a nacelle <NUM>, a rotor <NUM>, and blades <NUM>. The tower <NUM> extends upward in a vertical direction from the ground. The nacelle <NUM> is installed on the top of the tower <NUM> such that the nacelle <NUM> is rotatable relative to the tower <NUM>. The nacelle <NUM> rotates about the longitudinal direction of the tower <NUM>, which is yaw rotation. The nacelle <NUM> is driven by a drive device <NUM> having the motor <NUM>. The drive device <NUM> of the nacelle <NUM> may further include a speed reducer for decelerating the rotation of the motor <NUM> and outputting motive power with an increased torque to the pinion gear 24a. The nacelle <NUM> contains devices installed therein for wind power generation, such as a power transmission shaft and an electric power generator connected to the power transmission shaft. The rotor <NUM> is connected to the power transmission shaft in the nacelle <NUM> and is rotatable relative to the nacelle <NUM>. A plurality of blades <NUM> (three blades <NUM> in the example shown in <FIG>) are provided. The plurality of blades <NUM> extend radially from the rotational axis of the rotor <NUM> for the rotation relative to the nacelle <NUM>. The blades <NUM> are arranged at equal angular intervals around the rotational axis of the rotor <NUM>.

Each of the blades <NUM> is rotatable about a longitudinal direction thereof, i.e., in the pitch direction relative to the rotor <NUM>. A connection point between each blade <NUM> and the rotor <NUM> constitutes a movable section, so that the blade <NUM> and the rotor <NUM> are rotatable relative to each other. The blade <NUM> is rotationally driven by a drive device <NUM> having a motor <NUM>. The drive device <NUM> of the blade <NUM> may further include a speed reducer for decelerating the rotation of the motor <NUM> and outputting motive power with an increased torque to the pinion gear 24a.

For example, the first structure of the wind turbine <NUM> is the nacelle <NUM>, and the second structure is the tower <NUM>. In this case, the electromagnetic brake <NUM> brakes the relative rotation between the pinion gear 24a installed on the nacelle <NUM> and the ring gear <NUM> installed on the tower <NUM> so as to mesh with the pinion gear 24a. Additionally or alternatively, the electromagnetic brake <NUM> brakes the rotation of the motor <NUM> having the pinion gear 24a mounted thereto. In the case where the first structure is the nacelle <NUM> and the second structure is the tower <NUM>, control of the electromagnetic brake <NUM> by a contactless relay <NUM> (described later) can inhibit the ring gear <NUM> of the tower <NUM> from being damaged due to an abrupt change in the load acting between the drive device <NUM> of the nacelle <NUM> and the ring gear <NUM> of the tower <NUM>.

It is also possible that the first structure of the wind turbine <NUM> is the tower <NUM>, and the second structure is the nacelle <NUM>. In this case, the electromagnetic brake <NUM> brakes the relative rotation between the pinion gear 24a installed on the tower <NUM> and the ring gear <NUM> installed on the nacelle <NUM> so as to mesh with the pinion gear 24a. Additionally or alternatively, the electromagnetic brake <NUM> brakes the rotation of the motor <NUM> having the pinion gear 24a mounted thereto.

It is also possible the first structure of the wind turbine <NUM> is the blade <NUM>, and the second structure is the rotor <NUM>. In this case, the electromagnetic brake <NUM> brakes the relative rotation between the pinion gear 24a installed in the blade <NUM> and the ring gear <NUM> installed in the rotor <NUM> so as to mesh with the pinion gear 24a. Additionally or alternatively, the electromagnetic brake <NUM> brakes the rotation of the motor <NUM> having the pinion gear 24a mounted thereto.

The electromagnetic brake <NUM> may be configured in any way as long as it can brake at least one of the relative rotation between the pinion gear 24a installed in the first structure and the ring gear <NUM> installed in the second structure or the rotation of the motor <NUM> having the pinion gear 24a mounted thereto. For example, the electromagnetic brake <NUM> may brake the rotation of the rotating shaft of the motor <NUM> to brake the rotation of the pinion gear 24a mounted to the motor <NUM>. Besides, for example, the electromagnetic brake <NUM> may magnetically generate a frictional force acting between the first structure and the second structure to brake the relative rotation between the pinion gear 24a installed in the first structure and the ring gear <NUM> installed in the second structure.

As shown in <FIG>, the electromagnetic brake <NUM> is driven by a three-phase power supply. In the example shown in <FIG>, the electromagnetic brake <NUM> includes a coil <NUM> connected to the three-phase power supply. For example, the coil <NUM> is electrically powered by the three-phase power supply to generate the magnetic force for releasing the braking of the rotation of the motor <NUM>. It is also possible that the coil <NUM> is electrically powered by the three-phase power supply to generate the magnetic force for braking the rotation of the motor <NUM>. The three-phase power supply may also be used for rotationally driving the motor <NUM>.

The contactless relay <NUM> is disposed on the power supply line between the power supply for operation of the electromagnetic brake <NUM> and the electromagnetic brake <NUM> and is configured to open and close the power supply line using no mechanical contact. The contactless relay <NUM> is also called a solid-state relay. In the example shown in <FIG>, the contactless relay <NUM> is provided for each phase on the power supply line between the three-phase power supply and the electromagnetic brake <NUM>. That is, three contactless relays <NUM> are provided in the example shown in <FIG>. In the example shown in <FIG>, the power supply has three phases, whereas the contactless relays <NUM> have a single phase. The contactless relays <NUM> open and close the respective power supply lines simultaneously in accordance with a control signal from a control unit <NUM> (described later). With the three single-phase contactless relays <NUM> for simultaneously opening and closing the power supply lines for the three phases of the three-phase power supply in accordance with the control signal, opening/closing control for the electromagnetic brake <NUM> can be performed quickly in response to an abrupt change in the load acting between the drive device <NUM> and the ring gear <NUM>. The contactless relays <NUM> include, for example, a photocoupler. The photocoupler allows simple configuration of the contactless relays <NUM> for quickly opening and closing the power supply lines. The contactless relays <NUM> may include a MOSFET. The MOSFET allows simple configuration of the contactless relays <NUM> for quickly opening and closing the power supply lines. The three single-phase contactless relays <NUM> may be replaced with one three-phase contactless relay having a three-phase circuit. This can reduce the number of components.

The control unit <NUM> outputs to the contactless relay <NUM> a control signal for controlling the opening and closing of the power supply lines, thereby controlling the opening and closing of the power supply line by the contactless relay <NUM>. When a sensor <NUM> for sensing the load acting between the drive device <NUM> and the ring gear <NUM> senses a load (i.e., outputs a sensor output) exceeding a threshold value, the control unit <NUM> outputs to the contactless relay <NUM> an On signal as a control signal for an instruction for closing the power supply line. In response to the On signal, the contactless relay <NUM> closes the power supply line. When the power supply line is closed, electric power is supplied from the power supply to the electromagnetic brake <NUM>. Supplied with the electric power from the power supply, the electromagnetic brake <NUM> switches from a locking state in which the electromagnetic brake <NUM> brakes the rotation of the motor <NUM> to a freeing state in which the braking of the rotation of the motor <NUM> is released. The control unit <NUM> includes hardware such as a CPU and an electric circuit. Software may be used to realize a part of the control unit <NUM>.

To switch the electromagnetic brake <NUM> to the freeing state quickly in response to an abrupt change in the load acting between the drive device <NUM> and the ring gear <NUM>, the response speed of the contactless relay <NUM> for the On signal is preferably short. For example, the contactless relay <NUM> closes the power supply line at a response speed of <NUM> or less. The contactless relay <NUM> preferably closes the power supply line at a response speed of <NUM> or less. The contactless relay <NUM> more preferably closes the power supply line at a response speed of <NUM> or less.

The duration of the On signal is, for example, a short period on the millisecond order. Accordingly, the electromagnetic brake <NUM> releases the braking of the rotation of the motor <NUM> temporarily (in an instant), and then resumes the braking of the rotation of the motor <NUM>.

It is also possible that the electromagnetic brake <NUM> switches from the locking state to the freeing state when the supply of electric power from the power supply is stopped. In this case, when the sensor <NUM> senses a load exceeding the threshold value, the control unit <NUM> outputs to the contactless relay <NUM> an Off signal as a control signal for an instruction for opening the power supply line. In response to the Off signal, the contactless relay <NUM> opens the power supply line. When the power supply line is opened, the supply of electric power from the power supply to the electromagnetic brake <NUM> is stopped. Upon the stop of supply of electric power from the power supply, the electromagnetic brake <NUM> switches from the locking state to the freeing state. In this case, the response speed of the contactless relay <NUM> for the Off signal is preferably short. For example, the contactless relay <NUM> opens the power supply line at a response speed of <NUM> or less. The contactless relay <NUM> preferably opens the power supply line at a response speed of <NUM> or less. The contactless relay <NUM> more preferably opens the power supply line at a response speed of <NUM> or less.

The protection circuit <NUM> is disposed on the power supply line between the contactless relay <NUM> and the electromagnetic brake <NUM> and is configured to protect the wind turbine brake control device <NUM> against the surge occurring upon the On/Off operation of the contactless relay <NUM>. In the example shown in <FIG>, the protection circuit <NUM> includes three surge protection elements <NUM>. The surge protection elements <NUM> may be varistors, for example.

Next, examples of operation of the wind turbine brake control device <NUM> according to the first embodiment will now be described with reference to the flowcharts of <FIG> and <FIG>. <FIG> is a flowchart showing an example of operation of the wind turbine brake control device <NUM> according to the first embodiment. <FIG> shows an example of operation of the wind turbine brake control device <NUM> for the case where the electromagnetic brake <NUM> is configured to switch from the locking state to the freeing state when electric power is supplied from the power supply. <FIG> is a flowchart showing an example of operation of the wind turbine brake control device <NUM> according to a modification of the first embodiment. <FIG> shows an example of operation of the wind turbine brake control device <NUM> for the case where the electromagnetic brake <NUM> is configured to switch from the locking state to the freeing state when the supply of electric power from the power supply is stopped.

In the example shown in <FIG>, the control unit <NUM> first obtains from the sensor <NUM> the sensor output indicating a sensing result of the load acting between the drive device <NUM> and the ring gear <NUM> (step S1).

After obtaining the sensor output, the control unit <NUM> determines whether the sensor output exceeds a threshold value (step S2).

When the sensor output exceeds the threshold value (Yes in step S2), the control unit <NUM> outputs the On signal to the contactless relay <NUM> for closing the power supply line between the power supply and the electromagnetic brake <NUM> (step S3). The electromagnetic brake <NUM> is thus supplied with the electric power from the power supply, and the electromagnetic brake <NUM> switches from the locking state to the freeing state.

On the other hand, when the sensor output does not exceed the threshold value (No in step S2), the control unit <NUM> obtains the sensor output again (step S1).

In the example shown in <FIG>, the control unit <NUM> first obtains from the sensor <NUM> the sensor output indicating a sensing result of the load acting between the drive device <NUM> and the ring gear <NUM> (step S11).

After obtaining the sensor output, the control unit <NUM> determines whether the sensor output exceeds a threshold value (step S12).

When the sensor output exceeds the threshold value (Yes in step S12), the control unit <NUM> outputs the Off signal to the contactless relay <NUM> for opening the power supply line between the power supply and the electromagnetic brake <NUM> (step S13). The supply of electric power from the power supply to the electromagnetic brake <NUM> is thus stopped, and the electromagnetic brake <NUM> switches from the locking state to the freeing state.

On the other hand, when the sensor output does not exceed the threshold value (No in step S12), the control unit <NUM> obtains the sensor output again (step S11).

As described above, in the first embodiment, when an excessive load occurs due to an abrupt change in the load acting between the drive device <NUM> and the ring gear <NUM>, the sensor output exceeds the threshold value, and responsively the contactless relay <NUM> quickly closes or opens the power supply line between the power supply and the electromagnetic brake <NUM>. Since the power supply line is quickly closed or opened, it is possible to quickly release at least one of the braking of the relative rotation between the pinion gear 24a and the ring gear <NUM> or the braking of the rotation of the motor <NUM>. This configuration inhibits the damage of the ring gear <NUM> due to the load.

Next, the second embodiment of the invention will now be described with a more specific example of application. <FIG> is a sectional view showing a part of the tower <NUM> and the nacelle <NUM> in the wind turbine <NUM> according to the second embodiment. <FIG> is a plan view showing an arrangement of drive devices <NUM> in the movable section in the wind turbine <NUM> according to the second embodiment. <FIG> is a partially sectional side view of the drive device <NUM> in the wind turbine <NUM> according to the second embodiment. <FIG> is a partially sectional side view of an installation portion of the drive device <NUM> in the wind turbine <NUM> according to the second embodiment. <FIG> is a sectional view showing the electromagnetic brake <NUM> in the wind turbine brake control device <NUM> according to the second embodiment.

The drive device <NUM> is capable of driving the nacelle <NUM> installed so as to be rotatable relative to the tower <NUM> of the wind turbine <NUM>. Alternatively, the drive device <NUM> is capable of driving the blade <NUM> installed so as to be swingable in a pitch direction relative to the rotor <NUM> mounted to the nacelle <NUM>. That is, the drive device <NUM> can be used as a yaw drive device for carrying out yaw driving so as to cause the nacelle <NUM> to rotate relative to the tower <NUM> and also as a pitch drive device for carrying out pitch driving so as to cause a shaft portion of the blade <NUM> to rotate relative to the rotor <NUM>. While the following describes an example in which the drive device <NUM> is used as a yaw drive device, the present invention is also applicable to a case where the drive device <NUM> is used as a pitch drive device.

As shown in <FIG>, the nacelle <NUM> is installed on the top portion of the tower <NUM> so as to be rotatable relative thereto via a bearing <NUM> disposed on a bottom portion 103a of the nacelle <NUM>. A ring gear <NUM> having internal teeth formed on an inner periphery thereof is fixed to the top portion of the tower <NUM>. The ring gear <NUM> may have external teeth provided on an outer periphery thereof, instead of the internal teeth provided on the inner periphery thereof. In the drawings, the teeth of the ring gear <NUM> are not shown.

As shown in <FIG>, the ring gear <NUM> is formed in a circumferential shape and has a center axis Cm. The nacelle <NUM> rotates about the center axis Cm of the ring gear <NUM>. In the example shown, the center axis Cm of the ring gear <NUM> corresponds to the longitudinal direction of the tower <NUM>. In the following description, the direction parallel to the center axis Cm of the ring gear <NUM> is simply referred to also as "the axial direction dl.

In the wind turbine <NUM> shown, as shown in <FIG>, there are provided a pair of wind turbine drive systems <NUM> arranged in rotational symmetry about the center axis Cm of the ring gear <NUM>. Each of the wind turbine drive systems <NUM> includes three drive devices <NUM>. Six drive device bodies <NUM> in total included in the pair of wind turbine drive systems <NUM> are arranged along a circumference cl1 (see <FIG>) around the center axis Cm of the ring gear <NUM>. The three drive devices <NUM> included in each of the wind turbine drive systems <NUM> are arranged at regular intervals along the circumference cl1.

As shown in <FIG> and <FIG>, of the nacelle <NUM> (the first structure) and the tower <NUM> (the second structure) configured to rotate relative to each other, the drive devices <NUM> are provided in the nacelle <NUM>.

As shown in <FIG> and <FIG>, the drive devices <NUM> each have the drive device body <NUM> fixed to the nacelle <NUM> and a strain sensor <NUM> for sensing the strain of a bolt 30a that fixes the drive device body <NUM> to the nacelle <NUM>.

The drive device body <NUM> includes the motor <NUM>, a speed reducer <NUM>, and the pinion gear 24a. The motor <NUM> includes: a motor drive unit <NUM> for outputting motive power (i.e., a rotational force) from a drive shaft 48a (i.e., the rotating shaft) on the electric power supplied from the power supply; and the electromagnetic brake <NUM> for braking the rotation of the drive shaft 48a. The speed reducer <NUM> is connected to the drive shaft 48a of the motor <NUM> and an output shaft <NUM>. The speed reducer <NUM> decelerates the rotation of the motor <NUM> input from the drive shaft 48a and outputs a motive power with an increased torque to the output shaft <NUM>. The pinion gear 24a is provided on the output shaft <NUM> connected to the speed reducer <NUM>. The pinion gear 24a meshes with the teeth of the ring gear <NUM> provided on the tower <NUM>. The pinion gear 24a transmits to the ring gear <NUM> the motive power having a torque increased by the speed reducer <NUM> and thereby moves while rotating along the inner peripheral direction of the ring gear <NUM>. Thus, the drive device body <NUM> including the pinion gear 24a moves along the inner peripheral direction of the ring gear <NUM>, and the nacelle <NUM> having the drive device body <NUM> fixed thereto turns about the center axis Cm of the ring gear <NUM>.

By driving of the drive devices <NUM> thus configured, it is possible to cause the nacelle <NUM> (the first structure) as one side of the movable section of the wind turbine <NUM> to rotate relative to the tower <NUM> (the second structure) as the other side of the movable section of the wind turbine <NUM>. Particularly when the plurality of drive devices <NUM> included in the wind turbine drive system <NUM> mentioned above are operated in a synchronized manner, drive power of a sufficient magnitude is provided to properly turn the nacelle <NUM>, having a large weight, relative to the tower <NUM>.

More specifically, as shown in <FIG>, each of the drive devices <NUM> is fixed to the nacelle <NUM> via a fastener <NUM> disposed so as to extend through a through hole 22a formed through a flange <NUM> of the drive device body <NUM>. The fastener <NUM> includes a bolt 30a and a nut 30b. The strain sensor <NUM> is fixed to the nacelle <NUM> with a jig <NUM>. The strain sensor <NUM> senses the strain of the bolt 30a, thereby sensing the load acting between the drive device <NUM>, which includes the motor <NUM>, the speed reducer <NUM>, and the pinion gear 24a, and the ring gear <NUM>. The strain sensor <NUM> is a specific example of application of the sensor <NUM> described for the first embodiment. The sensor <NUM> is preferably mounted to a location that receives or is likely to receive no other disturbance than the load acting between the pinion gear 24a and the ring gear <NUM>. A specific and more preferable example of such a location is a case <NUM>.

As shown in <FIG>, the output shaft <NUM> of the drive device <NUM> is rotatably retained in the case <NUM>. The motor <NUM> is fixed to the top portion of the case <NUM>. The speed reducer <NUM> is housed in the case <NUM>. The speed reducer <NUM> may be configured in any manner as long as it can decelerate the rotation of the motor <NUM> and output a motive power with an increased torque. For example, the speed reducer <NUM> may be formed of an eccentric oscillating gear reduction mechanism, a planetary gear reduction mechanism, or a reduction mechanism combining the eccentric oscillating gear-type and the planetary gear-type.

An end portion of the output shaft <NUM> distal from the speed reducer <NUM> extends out of the case <NUM>, and the pinion gear 24a is formed at this extension portion of the output shaft <NUM>. As shown in <FIG> and <FIG>, the output shaft <NUM> penetrates a through-hole 103b formed through the bottom portion 103a of the nacelle <NUM>, such that the pinion gear 24a can mesh with the ring gear <NUM>. The pinion gear 24a has external teeth that mesh with the internal teeth of the ring gear <NUM>. The drive device <NUM> has a longitudinal axis corresponding to a rotation axis Cr of the output shaft <NUM>. In a state where the drive device <NUM> is fixed to the nacelle <NUM>, the rotation axis Cr of the output shaft <NUM> is parallel to an axial direction dl of the wind turbine <NUM>.

As shown in <FIG> and <FIG>, the case <NUM> is formed in a tubular shape and disposed such that the longitudinal axis thereof is positioned on the rotation axis Cr. The case <NUM> is open at both ends thereof along the rotation axis Cr. The pinion gear 24a of the output shaft <NUM> is exposed from an opening of the case <NUM> on the tower <NUM> side. The motor <NUM> is mounted to an opening of the case <NUM> on the opposite side to the tower <NUM>. Furthermore, the case <NUM> includes a flange <NUM>. In the example shown in <FIG>, the flange <NUM> is formed in an annular shape and extends along a circumference cl3 around the rotation axis Cr of the output shaft <NUM>. As shown in <FIG> and <FIG>, the through hole 22a is formed through the flange <NUM> so as to extend in the axial direction dl. A multitude of through holes 22a are formed on a circumference around the rotation axis Cr of the output shaft <NUM>. In the example shown, twelve through holes 22a are formed. The fastener <NUM> extends through the through-holes 22a formed in the flange <NUM> of the drive device body <NUM> and thus penetrates the flange <NUM>. In the example shown in <FIG>, the bolt 30a penetrates the flange <NUM> of the drive device body <NUM> and the bottom portion 103a of the nacelle <NUM>. The nut 30b is threadably engaged with the bolt 30a in a direction from the nacelle <NUM>. The fastener <NUM> formed of a combination of the bolt 30a and the nut 30b is provided for each of the through holes 22a of the drive device body <NUM>. In the example shown, each of the drive device bodies <NUM> is mounted to the nacelle <NUM> with twelve fasteners <NUM> at twelve locations.

The fastener <NUM> is not limited to the example shown. It is also possible that the nut 30b is replaced with a female screw formed in the through-hole of the nacelle <NUM>, and the male screw of the bolt 30a is threadably engaged with the female screw. In this case, the fastener <NUM> is formed of the bolt 30a, and the male screw of the bolt 30a is threadably engaged with the female screw in the through-hole of the nacelle <NUM>, thus making it possible to fix the drive device body <NUM> to the nacelle <NUM>.

The strain sensor <NUM> is electrically connected to the control unit <NUM> (see <FIG>) described for the first embodiment. The output of the strain sensor <NUM> indicating the sensing result of the strain of the bolt 30a is input to the control unit <NUM> in the form of an electric signal. The control unit <NUM> controls the braking of the rotation of the motor <NUM> by the electromagnetic brake <NUM> based on the output of the strain sensor <NUM>.

For example, the electromagnetic brake <NUM> may be configured as shown in <FIG>. In the example shown in <FIG>, the electromagnetic brake <NUM> is mounted to the top end portion of a cover <NUM> of the motor drive unit <NUM> on the opposite side to the speed reducer <NUM>. The electromagnetic brake <NUM> includes a housing 50a, a friction plate <NUM>, an armature <NUM>, an elastic member <NUM>, an electromagnet <NUM>, and a first friction plate connecting portion <NUM>.

The housing 50a is a structure that houses the friction plate <NUM>, the armature <NUM>, the elastic member <NUM>, the electromagnet <NUM>, and the first friction plate connecting portion <NUM>. The housing 50a is fixed to the cover <NUM> of the motor drive unit <NUM>.

The friction plate <NUM> is connected to the drive shaft 48a of the motor drive unit <NUM> via the first friction plate connecting portion <NUM>. The friction plate <NUM> has a through-hole that is penetrated by the top end portion of the drive shaft 48a.

The first friction plate connecting portion <NUM> includes a spline shaft 77a and a slide shaft 77b. The spline shaft 77a is fixed to an outer periphery of the top end portion of the drive shaft 48a through key-coupling with a key member (not shown) and engagement with a stopper ring 77c. The slide shaft 77b is mounted to the spline shaft 77a so as to be slidable in the axial direction. Furthermore, the first friction plate connecting portion <NUM> is provided with a spring mechanism (not shown) for situating the slide shaft 77b at a predetermined position in the axial direction relative to the spline shaft 77a. An inner periphery of the friction plate <NUM> is fixed to an edge portion of an outer periphery of a flange-shaped portion of the slide shaft 77b, so that the friction plate <NUM> is coupled integrally with the slide shaft 77b.

The electromagnetic brake <NUM> described above is configured such that, when the drive shaft 48a rotates, the spline shaft 77a, the slide shaft 77b, and the friction plate <NUM> also rotate together with the drive shaft 48a. In a state where the electromagnet <NUM> is excited, the slide shaft 77b and the friction plate <NUM> that are retained so as to be slidable in the axial direction relative to the drive shaft 48a and the spline shaft 77a are situated at a predetermined position in the axial direction of the spline shaft 77a by the spring mechanism. When disposed at this predetermined position, the friction plate <NUM> is separated from the armature <NUM> and a friction plate <NUM>, which will be described later.

The armature <NUM> is installed so as to be contactable with the friction plate <NUM>. When contacting with the friction plate <NUM>, the armature <NUM> generates a braking force for braking the rotation of the drive shaft 48a.

The friction plate <NUM> is provided at a location on the top end portion of the cover <NUM> of the motor drive unit <NUM> which location facing the friction plate <NUM>. The friction plate <NUM> is installed at such a position as to be contactable with the friction plate <NUM>.

The elastic member <NUM> is retained in an electromagnet body 53a of the electromagnet <NUM> (described later). The elastic member <NUM> presses the armature <NUM> in a direction from the electromagnet <NUM> toward the friction plate <NUM>. In the example shown in <FIG>, the elastic member <NUM> in the electromagnet body 53a includes two arrays of elastic members <NUM> arranged in the circumferential direction on the inner peripheral side and the outer peripheral side so as to be concentric about the drive shaft 48a. The above-mentioned form of arrangement of the elastic members <NUM> is merely an example, and the elastic members <NUM> may be arranged in other forms.

The electromagnet <NUM> includes the electromagnet body 53a and the coil <NUM> and attracts the armature <NUM> by a magnetic force so as to separate the armature <NUM> from the friction plate <NUM>.

The electromagnet body 53a is fixed to the housing 50a at the top end portion of the electromagnet body 53a on the opposite side to the side facing the armature <NUM>. The electromagnet body 53a has a plurality of elastic member retaining holes 53c open toward the armature <NUM>, and the elastic members <NUM> are disposed in the elastic member retaining holes 53c. The coil <NUM> is provided in the electromagnet body 53a.

When the electromagnetic brake <NUM> releases the braking of the rotation of the drive shaft 48a, electric power (i.e., an electric current) is supplied from the power supply to the coil <NUM> in response to the On signal from the control unit <NUM> so as to energize the electromagnet <NUM>. When the electromagnet <NUM> is energized and thus is brought into an exited state, the armature <NUM> is attracted to the coil <NUM> by a magnetic force generated at the electromagnet <NUM>. At this time, the armature <NUM> is attracted to the electromagnet <NUM> against an elastic force (spring force) of the elastic members <NUM>. Thus, the armature <NUM> is separated from the friction plate <NUM>, and the braking of the rotation of the drive shaft 48a is released. Accordingly, in the state where the electromagnet <NUM> is excited and the braking of the rotation of the drive shaft 48a is released, the armature <NUM> is brought into contact with the electromagnetic body 53a.

On the other hand, when the electromagnetic brake <NUM> brakes the rotation of the drive shaft 48a, the supply of electric power from the power supply to the coil <NUM> is stopped since the On signal is not output from the control unit <NUM>. Since the supply of electric power is stopped, the electromagnet <NUM> is demagnetized. When the electromagnet <NUM> is demagnetized, the armature <NUM> is pressed toward the friction plate <NUM> by an elastic force of the elastic members <NUM>, and thus the armature <NUM> contacts with the friction plate <NUM>. Thus, a frictional force is generated between the armature <NUM> and the friction plate <NUM>, and the rotation of the drive shaft 48a is braked. <FIG> shows a state in which the electromagnet <NUM> is demagnetized, and the rotation of the drive shaft 48a is braked.

In the state in which the electromagnet <NUM> is demagnetized and the drive shaft 48a is braked, the friction plate <NUM> is also contacted with the friction plate <NUM> by the elastic force acting from the armature <NUM>. Accordingly, when the electromagnet <NUM> is demagnetized, the friction plate <NUM> is sandwiched between the armature <NUM> and the friction plate <NUM> by an elastic force from the elastic members <NUM>. Thus, the rotation of the drive shaft 48a is braked very strongly by the frictional force generated between the armature <NUM> and the friction plate <NUM> and the frictional force generated between the friction plate <NUM> and the friction plate <NUM>.

In the second embodiment, the electromagnetic brake <NUM> brakes the rotation of the drive shaft 48a disposed upstream of the speed reducer <NUM> and thus having a smaller torque than the output shaft <NUM>. Therefore, the drive shaft 48a can be braked properly with a small braking force generated by the electromagnetic brake <NUM>.

Aspects of the present invention are not limited to the foregoing individual embodiments and embrace various modifications conceivable by those skilled in the art. Advantageous effects of the present invention are also not limited to those described above. That is, various additions, changes, and partial deletions are possible in a range not departing from the invention as defined by the claims.

Claim 1:
A wind turbine brake control device (<NUM>) comprising:
an electromagnetic brake (<NUM>) for braking at least one of relative rotation between a pinion gear (24a) installed in a first structure (<NUM>) and a ring gear (<NUM>) installed in a second structure (<NUM>) or rotation of a motor (<NUM>) having the pinion gear (24a) mounted thereto, the first structure (<NUM>) and the second structure (<NUM>) constituting a movable section of a wind turbine (<NUM>); and
a contactless relay (<NUM>) disposed on a power supply line between a power supply for operation of the electromagnetic brake (<NUM>) and the electromagnetic brake (<NUM>) and configured to open and close the power supply line, wherein
the power supply is a three-phase power supply, and the contactless relay is a three-phase relay or a single-phase relay.