JPH049720B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flywheel control device for controlling the attitude of a three-axis artificial satellite, and the invention relates to a flywheel control device for controlling the attitude of a three-axis artificial satellite, and controls drive of the flywheel so that the attitude of the satellite in orbit can be accurately and stably controlled. It is characterized by:

First, a conventional flywheel control device will be explained.

FIG. 1 is a diagram showing a conventional flywheel control device for an artificial satellite. In FIG. 1, 1 is a current controller, 2 is a sequencer having a switch S having contacts a, b, and c, and 3 is an input signal Therefore, an acceleration control circuit that controls output power, 4 a flywheel that stores rotational energy using an electric motor and a weight provided on its rotating shaft, and 5 a flywheel that stores the rotational energy of the flywheel as electrical energy in accordance with an input signal. 6 is a current transducer, A is an input torque signal as an attitude information signal of the satellite, and A is a rotation direction command signal that controls the rotation direction of the flywheel. , B are external signals that control the sequencer 2.

Now, when accelerating the flywheel 4, the current controller 1 compares the value obtained by converting the current flowing through the flywheel 4 into a voltage with the current transducer 6 and the input torque signal A, and the comparison output is sent to the switch S of the sequencer 2. Connect contacts a and b to external signal B
to "connect", amplify the power with acceleration control circuit 3,
Power is supplied to the flywheel 4. According to the input torque signal A, the rotation speed of the flywheel 4 increases, and the current flowing through the flywheel is converted into a voltage value by the current transducer 6, and the output is applied to the current controller 1 and compared with the input torque signal A. Then, the acceleration feedback control operation is performed.

Here, if the output of the current transducer 6 is larger than the input torque signal A, the output voltage of the acceleration control circuit 3 is reduced, and as a result, the current flowing to the flywheel 4 is reduced, and finally it becomes almost equal to the input torque signal A. It becomes constant at equal values.

Next, before explaining the deceleration control circuit 5, typical electrical characteristics of the flywheel 4 will be described with reference to FIG.

From the same figure, the upper side of the Y axis indicates positive motor voltage, the lower side indicates negative motor voltage, the left side of the X axis indicates the flywheel rotation direction to the right or left, and the right side of the X axis rotates in the opposite direction to the left side of the X axis. It is expressed by -ω and +ω.

A rotational direction command signal A is given to the rotational direction switching circuit in the flywheel 4, and at the same time the rotational direction switching circuit in the flywheel 4
When a positive motor voltage is applied according to the solid line curve, the flywheel rotation speed increases in proportion to the positive motor voltage.

Also, when the rotation direction command signal A is applied in the opposite direction to the above rotation direction and a positive voltage is applied to the flywheel 4, the rotation speed changes from point c to point d shown by the broken line in the figure in the opposite direction to the above rotation direction. will continue to increase.

The flywheel 4 is shown by a solid line in the figure. Point c ~ b
When the rotation speed of the flywheel 4 reaches point b on the solid line, a command signal in the opposite direction to the above rotation direction is given to the flywheel. , the terminal voltage of the flywheel generates a negative voltage (point e of the broken line in Figure 2), and the rotation speed of the flywheel 4 decreases while applying brakes on the line between points e and c, reaching zero rotation at ω = 0. When the positive motor voltage is applied to the flywheel 4 on the dotted lines c to d, an acceleration control operation is performed, and the rotational speed increases in the -ω direction in proportion to the voltage.

Note that even if the flywheel is initially located on the dashed line opposite to the above operation and is rotating at high speed, the same operation as above will occur.

The deceleration control circuit is shown below based on the flywheel operation shown in FIG.

When the flywheel 4 increases its rotational speed by the output of the acceleration control circuit 3 and is rotating at high speed at point b in FIG. A negative voltage is generated between the wheel terminals, and at the same time, contact a of the switch of sequencer 2 in Figure 1 is
and c are switched by external signal B. After the flywheel current is converted into current/voltage by the current transducer 6, the output of the current transducer 6 is compared with the input torque signal A, and the error signal is passed through the contacts a-c of the switch of the sequencer 2 and decelerated. A deceleration control circuit 5 is supplied to the control circuit 5 to cause the flywheel current to flow at a constant rate in proportion to the input torque signal.
Control with.

Conventional satellite attitude control devices are configured as described above, but when controlling the flywheel, the technology for the acceleration control mode has been cultivated for a long time and has almost become established. This flywheel-specific deceleration control is such that the flywheel terminal voltage becomes negative, the flywheel is decelerated while applying brakes, the rotational speed ω passes through zero, it begins to rotate in the opposite direction, and the acceleration mode reaches a predetermined motor voltage. It works. In this way, the control loop of the flywheel needs to operate stably over a wide range of rotations, from clockwise or counterclockwise rotation to reverse directions.

In particular, if the control loop becomes unstable, there is a risk of mechanical or electrical damage to the flywheel due to oscillation, noise, etc. Regarding electromagnetic interference, the ripples and noise leak into the satellite power bus line and interfere with other equipment onboard the satellite.

Conventional devices have sufficient back electromotive force when switching to deceleration mode, making it relatively easy to control the flywheel current, but the rotational energy stored in the flywheel is small, so it is difficult to reduce the internal resistance loss of the flywheel itself. Therefore, when the rotational speed of the flywheel decreases, the back electromotive force of the flywheel itself decreases, and as a result, it becomes impossible to keep the flywheel current constant.

Moreover, at low rotation speeds, not only could the flywheel current not be kept constant, but an unstable current would flow for a long time in proportion to the internal resistance, and there was a risk that the flywheel would stop when the rotation speed was close to zero. .

In this way, conventional devices have to control the flywheel rotation, which is unreliable in order to control the attitude of an artificial satellite.
Even in the rotational state of ~+ω, it could not be controlled with a constant current, and as a result, the satellite's attitude accuracy could not be maintained at a high level of accuracy.

Therefore, the present invention eliminates the above-mentioned conventional drawbacks, and when the flywheel is switched to the deceleration control mode, the deceleration control circuit operates, and for the medium speed rotation region, the deceleration control circuit and the acceleration control circuit operate. In addition, in order to enable the acceleration control circuit to operate at low speeds, a three-stage switching control method is used to control the flywheel current at a constant current in a wide rotation range from -ω to +ω according to the input torque signal. This invention provides a flywheel control device for an artificial satellite that performs control.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a diagram showing a flywheel control device for an artificial satellite according to the present invention. In the figure, 1 is a current controller, 2 is _a first switch S having contacts a, b, and c; A sequencer with a second switch _S2 having connected contacts d and e, 3 an acceleration control circuit, 4 a flywheel, 5 a deceleration control circuit, 6 a current transducer, 7 a switch control circuit, and a Torque signal, A
is the rotation direction command signal.

First, the rotation direction command signal A is
When set to operate on the dotted line, the input torque signal A and the output of the current transistor 6 are compared in the current controller 1, and the difference signal enters the acceleration control circuit 3 through a and b of the sequencer 2. , a current proportional to the input torque signal A is output from the acceleration control circuit 3, and the rotation speed of the flywheel 4 increases as the motor voltage increases. After the rotation speed reaches point b on the line, the flywheel 4
If an attempt is made to set the rotation to be in the opposite direction -ω, a signal opposite to the set rotation direction command signal A is given.

After giving the command signal A, the output terminal voltage of the flywheel 4 becomes negative as shown in Fig. 2.
The switch control circuit 7 sends S1 to the sequencer 2 a-
A signal for switching to the circuit c is output, and the deceleration control circuit 5 operates.

Details of the operation of the deceleration control circuit 5 will be described with reference to FIG.

The input voltage of the flywheel 4 is signal-processed by the switch control circuit 7, and the contacts a-c of the first switch _S1 of the sequencer 2 are "closed" and the contacts e-d of the second switch _S2 are "open". Leave as is.

The deceleration control mode consists of current controller 1,
The sequencer 2, deceleration control circuit 5, flywheel 4, and current transducer 1 form a feedback loop that controls the current flowing through the flywheel 4.

Since energy is consumed from the flywheel 4 by the deceleration control circuit 5, the rotation speed of the flywheel 4 decreases over time, so the back electromotive force of the motor decreases, and due to the internal resistance loss of the flywheel described above. , the current proportional to the input torque signal A is no longer maintained.

The switch control circuit 7 uses the motor terminal voltage of the flywheel 4 at this time as a reference voltage in advance.
If the flywheel 4 terminal voltage falls below the reference voltage, the switch control circuit 7 will detect this and close contacts a and b of the first switch _S1 of the sequencer 2, and close the second switch S1. S ₂ contact d-e
The deceleration control circuit 5, the acceleration control circuit 3, the flywheel 4, and the current transducer 6 are connected in parallel by the current controller ₁ , the first switch S1, and the second switch _S2 . By forming a feedback loop with the acceleration control circuit 3, the current insufficient in the deceleration control mode is compensated for by the acceleration control circuit 3, and the current flowing through the flywheel is controlled to be constant. In other words, switch contacts a-b "contact", d-e "contact"
Immediately after switching to the deceleration control mode, the back electromotive force of the flywheel 4 in the deceleration control mode is still large, so the current flowing through the flywheel 4 is kept constant only by the deceleration control circuit 5, but as time passes, the flywheel back electromotive force increases. As a result, the terminal voltage of the flywheel 4 decreases.

As time continues, the operation of the deceleration control circuit 5 and the operation of the acceleration control circuit 3 gradually change the current ratio while keeping the current of the flywheel 4 constant, and the current from the acceleration control circuit 3 gradually increases.

When the current supply to the deceleration control circuit 5 cannot satisfy the current required by the input torque signal A, the switch control circuit 7 activates the first switch of the sequencer 2.
By controlling the contacts a and b of _S1 to "close" and the contacts de to second switch _S2 to "open," the current controller 1, acceleration control circuit 3, flywheel 4, and current transducer 6 are controlled. The flywheel current is kept constant by forming a feedback loop.

That is, it enters the acceleration control mode, is completely disconnected from the deceleration control circuit 5, and accelerates the flywheel 4.

As explained above, the present invention can control the rotation of the flywheel in the opposite direction from the clockwise or counterclockwise rotation direction, and can stably control the entire rotation range with a constant current value proportional to the input torque signal. .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a conventional flywheel control device for an artificial satellite, FIG. 2 is a diagram showing electrical characteristics of the flywheel, and FIG. 3 is a schematic diagram showing an embodiment of the present invention. In the figure, 1 is a current controller, 2 is a sequencer, 3 is an acceleration control circuit, 4 is a flywheel, and 5
is a deceleration control circuit, 6 is a current transducer, and 7 is a deceleration control circuit.
is a switch control circuit, _S1 is a first switch, _S2 is a second switch, A is an input torque signal, A is a rotation direction command signal, and B is an external signal. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Claims] 1. A current transducer that converts the output current of the flywheel whose rotation direction is controlled by a rotation direction command signal into a voltage, an input torque signal for controlling the rotation speed of the flywheel, and an output of the current transducer. an acceleration control circuit that controls the rotational speed of the flywheel in the acceleration direction based on the output of the current controller, and an acceleration control circuit that controls the rotational speed of the flywheel in the deceleration direction based on the output of the current controller. a deceleration control circuit; a first switch connecting an output terminal of the current controller to an input terminal of the acceleration control circuit or the deceleration control circuit; and an input terminal of the acceleration control circuit and an input terminal of the deceleration control circuit; A feedback loop of the current controller, the acceleration control circuit, the flywheel, and the current transducer according to the increase or decrease of the input voltage of the flywheel determined by the second switch to be connected and the acceleration control circuit and deceleration control circuit. , the above current controller, a deceleration control circuit, a flywheel and a current transducer feedback loop, or the above current controller, a parallel connection acceleration control circuit and deceleration control circuit, a flywheel and a current transducer feedback loop. A flywheel control device for an artificial satellite, characterized in that the first and second switches are provided with a drive control switch control circuit so as to form any one of the above.