JP6955865B2 - Drive control method and reaction wheel of the rotating body - Google Patents

Description

The present invention relates to, for example, a motor technology for driving a rotating body such as a flywheel and a rotating device, and can perform highly accurate control that is not affected by loss torque, particularly in torque control required for posture control of an artificial satellite. It provides a rotating device and its control technology.

As shown in Fig. 1, the wheel assembly (reaction wheel) mounted on the artificial satellite accelerates or decelerates the rotor inside it by a motor and controls its rotation speed, thereby stabilizing the gyro by the angular momentum. It has the function of generating control torque and accumulating angular momentum by absorbing disturbance torque and the like with respect to the artificial satellite.

In the case of wheel acceleration, the command torque value is received and an acceleration current is applied to the motor winding through the motor control circuit. On the other hand, in the case of deceleration, the motor current is passed in the direction of generating torque in the opposite deceleration direction. The rotation speed of the rotor is changed by the motor torque generated by this, and the reaction torque is transmitted to the artificial satellite through the motor stator.

The wheel assembly receives a torque command signal from an artificial satellite and sends a motor current proportional to the torque command signal to the motor in a motor control circuit to rotate the wheel rotor. During deceleration, the motor operates as a generator and generates torque that reduces the number of revolutions by extracting the rotational energy (mechanical energy) stored in the rotor as an electric current.

The reaction force of the rotor rotation torque generated at this time is transmitted to the artificial satellite body, and becomes the torque for rotating the artificial satellite body.

The torque generated by the motor due to the motor current minus the loss torque generated by the bearings supporting the motor and the rotor is the output torque (T) from the wheel to the outside.
T _{= K} T · I- loss torque (Equation 1)
Here, _KT is a torque scale factor [Nm / A], and I is a motor current [A].

In addition, the vibration (translational force, rotational torque) when the rotor rotates is transmitted to the satellite as a disturbance.

The configuration of the reaction wheel assembly is as follows.
・ Rotor that supports angular momentum ・ Bearing that supports the rotor ・ DC motor that drives the rotor (brushless DC motor is common)
-Control board for driving a DC motor-And a housing that includes the above components

In the drive of the brushless DC motor of the conventional reaction wheel, as shown in FIG. 2, the position of the rotor is detected by the Hall element, and the drive is performed by changing the polarity flowing through the coil (winding). Normally, the rotor is a permanent magnet and the stator is a coil. For example, three-phase (U-phase, V-phase, W-phase) stator windings are arranged at 120 ° intervals, and three Hall elements are arranged at 120 ° intervals, and a square wave magnetized on the rotor. And the change in the magnetic flux of the trapezoidal wave is converted into a voltage and output. The tacho pulse from the Hall element is generally 4 pulses per rotation in an 8-pole motor.

There are roughly two roles of the Hall element, one is the role of communication that changes the polarity of the drive current, and the other is the loop control of the reaction wheel (voltage control, speed control, or torque control). It is used as a speed sensor.

FIG. 3 shows a torque control loop of a conventional wheel. Current feedback is performed in this system. That is, the command value command alpha (angular acceleration: [rad / s ^2]) by integrating the velocity information omega (acceleration: [rad / s]) and then, the induced voltage coefficient _{(K E: [Vs / rad} ]) Converts to more voltage [V] and excites the motor. The current I [A] of this motor is detected, converted to α', fed back, and compared with the command value α to output a desired torque. In addition, the angular velocity ω [rad / s] is obtained from the Hall sensor output and fed back to expect speed stability. Here, J in FIG. 3 is the rotor moment of inertia [kg · m ² ], and _KT is the torque constant [N m / A].

Arrangement of Figure 3 is a general torque control arrangement, the loop basically because it equations T = K T _· I base, the influence of the loss torque as shown in the above formula 1 Enters. Further, since the angular velocity ω is obtained from the Hall sensor by taco pulse (generally 4 pulses / 1 rotation), accuracy cannot be obtained at low speed rotation.

As described above, in the torque control of the reaction wheel using the conventional Hall element,
(1) The effect of loss torque appears.
(2) The speed accuracy at low rotation is poor, and it is not possible to respond to low torque commands.
(3) The motor is driven by duty control by PWM (Pulse Width Modulation), but since it is basically a square wave excitation, current ripple is large and it tends to affect the control accuracy.

The problem of the number of pulses can be solved by using an encoder, but it is generally considered that the cost is high. Further, for example, Patent Document 1 is known regarding the reaction wheel and its drive control.

Japanese Unexamined Patent Publication No. 2014-105752

What is required from the background mentioned above is
(B) Sine wave drive of the motor (b) Torque control method that is not affected by loss torque (c) Increase in speed pulse (d) Low price.
In particular, there is a demand for high-performance drive control for a rotating body such as a flywheel, and a rotating device for realizing such drive control.

The present invention is a drive control method used for driving a reaction wheel for controlling the attitude of an artificial satellite. based on the output signal of magnetosensitive, said generating a commutation signal as a phase excitation switching signal of the three-phase motor for rotating the driven rotating body, on the basis of the commutation signal, and drives the front Symbol 3-phase motor In the drive control method of the rotated body, the magnetizing element is a Hall sensor having a resolver function capable of outputting a sine wave and a cos wave based on the rotation phase of the rotated body as the output signal, and is from the outside. The angular velocity calculated from the command value, the angular velocity of the rotated body calculated from the sine wave and the cos wave as the output signal, and the rotation phase of the rotated body calculated from the sine wave and the cos wave. A method of driving and controlling a rotated body is characterized in that a commutation signal is generated based on the above and the three-phase motor is driven and controlled.

INDUSTRIAL APPLICABILITY The present invention can realize a high-performance drive control method for a rotating body, a rotation device, an attitude control device for an artificial satellite, and an attitude control method for an artificial satellite.

A block diagram showing satellite dynamics and reaction wheel functionality. The figure which shows the connection with the control circuit of the reaction wheel which used the conventional Hall element. The figure which shows an example of the torque control loop of the conventional reaction wheel. The torque control block diagram of this invention. Cross-sectional view of the outer ring rotation type reaction wheel.

Hereinafter, embodiments of the present invention will be described in detail.

In the present embodiment, the magnetic sensing element is arranged to face the magnet provided on the flywheel, which is an example of the rotated body, and the flywheel is rotationally driven based on the output signal of the magnetic sensing element. It is characterized in that it generates a communication signal that is a phase excitation switching signal for the motor (U-phase, V-phase, and W-phase) and controls the 3-phase motor through a PWM control inverter based on the communication signal. ..

Here, the magnetic sensing element senses a change in the magnetic field of a magnet that rotates integrally with the fly wheel. Specifically, each part of the N pole / S pole forming the magnetic field is located at a position facing the magnetic sensing element. By rotating, the magnetic sensing element fixed at the opposite position detects the change in the magnetic field of the magnet. Then, such a magnetic sensing element outputs a sine wave analog signal or the like as an output signal based on the change in the magnetic field of the magnet. The magnetic sensitive element of the present embodiment has a resolver function, and will be described below as a resolver type Hall sensor.

The present invention realizes driving of a highly accurate three-phase motor with a PWM control inverter by newly incorporating the following elements [A] and [B] using the output signal of the resolver type Hall sensor. Is.
[A] Detecting the rotor position from the sine wave / cos wave of the sensor output [B] Generating speed information from the sensor output (Phasing the phase angle of the sine wave / cos wave to create high-resolution speed information matter)

Here, in the present invention, as a means for driving a DC motor (three-phase motor) in a sine wave, the introduction of the above-mentioned pulse width modulation method, that is, a PWM control inverter circuit is one of the main points. Instead of the conventional Hall element, a sensor that determines the switching timing of the exciting coil is required. That is, since it is a sensorless drive that does not use individual Hall elements, the rotor position must be detected by some means.

When the outputs of the three Hall elements are amplified by individual position detection amplifiers as in the conventional configuration (Fig. 2), the outputs are processed by the switching matrix, and the rotation of the rotor is controlled, the rotor is controlled. Requires a separate Hall element and position detection amplifier.

On the other hand, the present invention applies a resolver-type Hall sensor that is arranged to face a magnet provided on the side to be rotated, without having to provide such an individual Hall element and a position detection amplifier. That is, by incorporating a sensor unit composed of a resolver type Hall sensor and a magnet into the rotation drive mechanism of the flywheel, rotor position detection is performed based on the sin wave / cos wave which is the output signal of the resolver type Hall sensor. It can be performed with high accuracy, and the rotation detection configuration can be simplified.

In the present embodiment, the rotation angle phase of the rotor is obtained from the output from the resolver type Hall sensor described above, that is, the sine wave output and the cos wave output, and the phase of the induced voltage of the motor is matched with this to adjust the drive timing of the transistor. By doing so, it is possible to drive the motor with high accuracy. Based on this phase adjustment, although details will be described later, a motor-driven communication signal, that is, a phase excitation switching signal for a three-phase motor is generated. Basically, this drive is energized by 180 °.

Here, the drive control of the three-phase motor through the PWM control inverter using the resolver type Hall sensor described above will be described. FIG. 4 shows a block diagram of torque control of the motor.
First, regarding the input of torque control, since the input 101 of the command value from the outside is the command angular acceleration α [rad / s ² ], this is integrated to obtain the angular velocity ω, and the target (velocity limit). ) Is determined, the time is determined from α / ω, the angular acceleration α and the angular velocity ω are input (102), and the desired modulated wave generation 111 is performed. At this time, in the modulated wave generation 111, the phase of the rotor position detection result based on the sine wave / cos wave from the resolver type Hall sensor 30 and the induced voltage of the motor is adjusted (108), and the switching timing of the motor is adjusted. decide. On the other hand, in this modulated wave generation 111, a desired modulated wave is generated (103) in response to the command values of the angular acceleration α and the angular acceleration ω. This desired waveform is input to the comparator 112, a sawtooth wave (triangle wave) is input to the other terminal of the comparator 112, a voltage pulse is generated (105), and this output is input to the inverter 32. The motor 33 is driven by an operation according to a desired modulated wave. This is the drive control of the motor using the PWM control inverter method in the present invention.

Further, since the resolver type hall sensor 30 is also driven by the drive of the motor 33, the resolver type hall sensor 30 outputs the angular velocity ω [rad / s] as the speed information 106, and the angular velocity ω of the command value is output. By comparing with [rad / s], the motor 33 can be driven by the deviation, that is, the motor 33 can be driven by the feedback control 110 with high-precision torque control.

Here, when the torque T [Nm] of the 3-phase motor, the angular acceleration α [rad / s ² ] of the 3-phase motor, and the moment of inertia J [kg ・ m ² ] of the flywheel, the torque control of the 3-phase motor is , Derived by Equation 2 below.
T = J · α (Equation 2)
Since the control system is constructed based on the basic equation of the above equation 2, there is no influence of loss torque (torque loss) in motor control.

The sensor unit in the present invention is cheaper than an encoder or a resolver, and leads to a reduction in the cost of the entire reaction wheel. Further, the number of wirings can be reduced as compared with the Hall elements arranged every 120 °, and the cost can be reduced from this point as well. Further, the motor drive of the reaction wheel of the present invention is a sine wave, and the current ripple is small.

Hereinafter, the present invention will be described in detail with reference to the drawings based on the embodiments, but the present invention is not limited to the following embodiments.

FIG. 5 is a cross-sectional view of the outer ring rotation type reaction wheel, and FIG. 10 shows the entire reaction wheel. The wheel rotor (flywheel) 13 that generates angular momentum is attached to the outer ring 16a of the bearing 16, and the inner ring 16b of the bearing 16 that serves as a rotation holding portion is fixed to the shaft (fixed shaft portion) 14. The shaft 14 is attached to the base 15. Since the shaft 14 is fixed, the reaction wheel of this embodiment is an outer ring rotation type wheel.

The rotor 13 is provided with a skirt portion 13a protruding in parallel with the axial direction of the rotation axis on the outer side in the radial direction. A magnet 18 is attached to the skirt portion 13a, and a current is passed through the motor coil 17 to allow the rotor to flow. 13 is rotationally driven around the rotation axis x of the shaft 14.

The pedestal 11 is attached to the rotor 13 that rotates in this way, and the magnet 12 that forms a part of the sensor unit is attached to the lower end surface facing the shaft 14. On the other hand, the resolver type Hall sensor 30 that constitutes the sensor unit together with the magnet 12 is attached to one end of the shaft 14 with an appropriate space (interval) 20 facing the magnet 12.

Further, in FIG. 5, a control board 40 for controlling the drive of the rotor 13 is provided at the lower end of the base 15. The control board 40 and the resolver type Hall sensor 30 are connected by a communication cable 25 through a wiring path 14a provided so as to penetrate the shaft 14 in the coaxial direction with the rotation shaft. A signal from the resolver type Hall sensor 30 is transmitted to the control board 40 through the communication cable 25, and the energization of the motor coil 17 is controlled via the control board 40. As a result, the rotational drive of the rotor 13 is controlled.

As described above, in the present embodiment, by providing the wiring path 14a penetrating the shaft 14, the resolver type Hall sensor 30 can be arranged in the vicinity of the rotation center of the rotor 13, and the rotary bearing structure of the rotor 13 is provided in the shaft 14. Wiring can be performed at the shortest distance to the control board 40 through the wiring path 14a of the above. That is, according to the configuration of the present embodiment, it is easy to incorporate the sensor unit with wiring into the movable center of the reaction wheel body, that is, on the line of the rotation axis x and the rotation center of the rotor 13, and to the control board 40. Can be stored compactly including wiring.

The reaction wheel of the present invention can be used as an actuator for most satellites. Especially in torque control, since there is no error due to the friction torque of the bearing, it boasts a significantly higher resolution than the conventional product and its output linearity. Since it is excellent, it exerts its power as an actuator for high-precision pointing. That is, the reaction wheel of the present invention and its drive control method can control the attitude of the artificial satellite with high accuracy by incorporating it into an attitude control device that controls the attitude of the artificial satellite or the like. Since the reaction wheel of the present invention can be realized at low cost, it can be applied to equipment that requires high-precision torque control in ordinary industrial equipment, and a wide range of demand can be expected.

Although the present invention has been described in detail with reference to specific examples, the present invention is not limited to the above-described embodiment.
In FIG. 5 of the above-described embodiment, the structure in which the present invention is applied to the outer ring rotation type reaction wheel has been illustrated and described, but the present invention is of course not limited to this, and for example, the bearing inner ring, that is, the shaft rotates. The sensor module can also be applied to the reaction wheel, in which case the objective is achieved by attaching a magnet to the shaft and attaching the sensor to the base 15.

<Additional notes>
The present invention is not limited to the above-described embodiment, and has the following features.
[Feature 1]
A reaction wheel equipped with a sensor module in which a magnetic sensing element and a magnet are arranged so as to face each other. The phase of this sensor output and the induced voltage waveform of the motor is adjusted to form a three-phase communication signal without a sensor. A reaction wheel that enables driving.
[Feature 2]
A reaction wheel that uses a PWM control inverter method to drive the motor of the reaction wheel, generates pulses with the desired waveform (modulated wave) and carrier as command values, and uses 180 ° energization and sine wave drive.
[Feature 3]
A reaction wheel that combines the above [Feature 1] and [Feature 2] and has a system that feeds back the speed output of the sensor module so as to follow the speed as the command value and eliminates the error with the comparator.
[Feature 4]
A reaction wheel that can control torque without the influence of loss torque by the control design based on the equation of T = J · α in the control system of the above [Feature 3].
[Feature 5]
The torque control loop is designed to follow this ramp input with the desired ramp input based on the angular acceleration α [rad / s ² ] and the angular velocity ω [rad / s] of the speed limit as the modulated wave. In the system, the follower is a reaction wheel that operates by comparing the command value with the speed based on the rotation pulse obtained from the phase difference of sin and cos of the sensor module.

Further, as a rotating device that can be suitably used for the drive system of any one of the above-mentioned [feature 1] to [feature 5], a rotating device having the following configuration can be mentioned.
[Structure 1]
The drive unit that rotates the rotating body and
A rotation holding portion that rotatably holds the body to be rotated around a rotation axis is provided.
In the rotation holding portion, a magnetic sensitive element that detects a change in the magnetic field generated by the magnet of the rotated body as the driven body is driven to rotate is provided in the axial direction of the rotating shaft. A rotating device characterized in that it is provided facing the magnet.
[Structure 2]
A control board that generates a drive signal for driving the drive unit based on the output signal of the magnetic sensitive element is provided.
The rotation holding portion is provided with a fixed shaft portion coaxial with the axis of the rotating shaft.
A rotating device characterized in that the magnetic sensitive element and the control board are connected by a communication cable through a wiring path provided so as to penetrate the fixed shaft portion in the axial direction.
The above-described rotating device or its drive control method can be suitably used for driving a reaction wheel for controlling the attitude of an artificial satellite and widely applicable to an attitude control device for an artificial satellite.

10 Reaction wheel 11 Magnet pedestal 12 Magnet for sensor module 13 Rotor 14 Shaft 15 Base 16 Bearing 16a Bearing outer ring 16b Bearing inner ring 17 Motor coil 18 Motor magnet rotor 20 Space (interval)
30 Resolver type Hall sensor (sensor unit)
31 IC (LSI)
32 Three-phase inverter 33 Motor 40 Control board

Claims (7)

This is a drive control method used to drive a reaction wheel for controlling the attitude of an artificial satellite. A magnetic sensory element is arranged so as to face a magnet provided on a rotating body, and the output of the magnetic sensory element is output. based on the signal, the generating a commutation signal as a phase excitation switching signal of the three-phase motor for rotating the driven rotating body, on the basis of the commutation signal, the driven rotating body to drive the front Symbol 3-phase motor In the drive control method
The magnetizing element is a hall sensor having a resolver function capable of outputting a sine wave and a cos wave based on the rotation phase of the rotating body as the output signal.
The angular velocity calculated from the command value from the outside, the angular velocity of the rotated body calculated from the sine wave and the cos wave as the output signal, and the rotation of the rotated body calculated from the sine wave and the cos wave. A method for driving and controlling a driven object, which comprises generating the communicating signal based on the phase and driving and controlling the three-phase motor. The first aspect of claim 1, wherein the commutation signal is generated by matching the rotation angle of the rotating body obtained from the output signal of the magnetizing element with the phase of the induced voltage of the three-phase motor. Drive control method for the rotating body. A desired modulated wave is generated by the angular acceleration which is a command value from the outside and the angular acceleration obtained by integrating the angular acceleration, and the modulated wave is passed through a three-phase inverter based on the pulse waveform converted by pulse width modulation. The drive control method for a driven object according to claim 1 or 2, wherein a PWM control inverter system for driving the three-phase motor is adopted. Based on the comparison result between the angular velocity determined based on the angular acceleration which is a command value from the outside and the angular velocity obtained from the rotational pulse based on the phase difference between the sine wave and the cos wave which are the output signals of the magnetizing element. The drive control method for a rotated object according to any one of claims 1 to 3, wherein the three-phase motor is controlled. When the torque of the three-phase motor is controlled by the torque T [Nm] of the three-phase motor, the angular acceleration α [rad / s2] of the three-phase motor, and the moment of inertia J [kg · m2] of the rotated object. , The drive control method for a rotated object according to any one of claims 1 to 4, wherein the conditional expression of T = J · α is satisfied. A reaction wheel including a rotating body that is driven and controlled by the drive control method according to any one of claims 1 to 5.
A rotation holding portion for rotatably holding the body to be rotated around a rotation axis is provided.
Wherein the rotary holding unit, with the rotation of the driven rotating body by the three-phase motor, said sensing element for detecting a change in magnetic field emanating previous KOR Gunetto, the magnet in the axial direction of the rotary shaft A reaction wheel characterized by being installed facing the magnet. A control board that generates a drive signal for driving a drive unit that rotates the body to be rotated based on an output signal of the magnetizing element is provided.
The rotation holding portion is provided with a fixed shaft portion coaxial with the axis of the rotating shaft.
The reaction wheel according to claim 6, wherein the magnetically sensitive element and the control board are connected by a communication cable through a wiring path provided so as to penetrate the fixed shaft portion in the axial direction.

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