JPH0544799U - Drive circuit for re-acceleration wheel - Google Patents

Abstract

(57) [Summary] [Purpose] To eliminate the inrush current during deceleration of the reaction wheel and reduce the operational delay during reacceleration. [Structure] A one-shot circuit that temporarily decelerates the integrator each time the torque direction command changes, and a delay circuit that delays the change in the torque direction command by a predetermined time shifts the counter electromotive voltage timing. By informing the commutation circuit, inrush current of the power supply of the motor drive circuit is prevented. In addition, the first logic circuit that determines whether the combination of the torque direction command and the rotation direction command signal of the reaction wheel is re-acceleration of the reaction wheel, and if the determination result is re-acceleration, the output of the one-shot circuit is output. The second logic circuit, which does not pass through, does not decelerate the integrator and prevents inrush current of the power supply of the motor drive circuit.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This device is a reaction wheel drive circuit used for attitude control, and has a function to prevent inrush current that occurs when the reaction wheel motor is switched between acceleration and deceleration.

[0002]

[Prior Art]

 For example, a reaction wheel is used for attitude control of a satellite. The principle of posture control will be described with reference to FIG. In Fig. 4 (a), when limited to control around one axis, one flywheel 41 is attached in the axial direction with the rotation axis 42 in parallel, rotates at a constant speed, and the satellite 43 remains stationary. It is assumed that The value obtained by multiplying the wheel speed by the moment of inertia of the wheel is also the angular momentum of the wheel. If there is no disturbance torque, the satellite does not move due to the law of conservation of angular momentum. If the wheel speed is accelerated, the angular momentum of the wheel increases, so that the satellite body has an opposite angular opposite angular momentum. In other words, the reaction torque of wheel acceleration is applied to the satellite and reverses. Therefore, the torque in the direction opposite to the wheel acceleration can be used as the control torque for canceling the disturbance torque or changing the attitude. In FIG. 4B, if the disturbance torque 44 acts on the satellite body in the counterclockwise direction, for example. Then, since the satellite rotates counterclockwise, if the wheel is accelerated counterclockwise to return it, the reaction torque 45 by the wheel acts and the attitude of the satellite is maintained (Fig. 4 (c)). In other words, the disturbance torque causes the wheel to rotate in place of the satellite.

As described above, the rotation speed of the reaction wheel is accelerated and decelerated to generate the torque. As a circuit for this purpose, a circuit having a configuration as shown in FIG. 5 is used. In FIG. 5, 1 is an integrator that applies a torque command and integrates it, 2 is a comparator that compares the output of the integrator 1 with a sawtooth wave, and generates a pulse having a width proportional to the output of the integrator 3, 3 Is an acceleration circuit that controls the voltage required for acceleration of the reaction wheel according to the output of the integrator 1 input via the comparator 2, 4 is the control target, and the reaction wheel represented by a brushless DC motor, 5 is the A deceleration circuit that acts as a impedance converter and flows a current due to a back electromotive force during deceleration of the reaction wheel 4, a commutation circuit 6 that receives a torque direction command TD and gives a command to the reaction wheel to switch the torque generation direction, 7 is a resistor for converting the current flowing in the reaction wheel 4 into a voltage, and 8 is a resistor for inputting the voltage generated in the resistor 7. Ru compensation der to feed back to the input of the integrator 1.

This reaction wheel drive circuit has a first-order lag control system using the integrator 1. In addition, since the motor current flows in the same direction during acceleration and deceleration, the positive output of the integrator 1 is set to the acceleration state, and the negative output is set to the deceleration state. The motor current is controlled so as to increase with one output increase.

When an arbitrary torque command (positive DC voltage) is applied to the input of the integrator 1, the output of the integrator 1 increases in the positive direction (the integrator gain polarity is positive). This increase in output potential is converted into an increase in pulse width by the next-stage comparator 2 and prolongs the ON time of the switching transistor (not shown) in the acceleration circuit 3. The voltage supplied to the motor of the reaction wheel 4 by the power supply increases, and the motor current increases. The voltage resulting from this current is fed back by the compensation circuit 8, and the output of the integrator 1 is held and the motor current is controlled where it is balanced with the torque command. The accelerating circuit 3 controls the pulse width in this way. The reaction wheel 4 generates a motor torque by this motor current and increases the rotation speed. The operation at this time is expressed by the following equation (1).

V _M = K _T ω + I _M R + V _T (1)

Where V _M is a motor voltage (V) supplied by the acceleration circuit 3, K _{T is} a motor torque scale factor (Nm / A) of the reaction wheel 4, and ω is a motor rotation speed of the reaction wheel 4 ( rad / sec), I _M : Motor current (A) of reaction wheel 4, R: Motor winding resistance (Ω) of reaction wheel 4, V _T : Motor switching transistor voltage drop (V) of reaction wheel 4, K _T ω: Motor back electromotive force (V) in acceleration state

That is, as the rotation speed increases, the motor current decreases, the current corresponding to an arbitrary torque command is held, the output of the integrator 1 increases, and the supply voltage V _M to the motor increases. In this way, the motor current is controlled.

In the above state, the torque direction command TD is reversed, the timing of the commutation circuit 6 of the reaction wheel 4 is changed, a torque opposite to the rotation direction is generated, and the deceleration state is entered. At this time, the polarity of the back electromotive force associated with the rotation speed of the reaction wheel 4 is reversed. This back electromotive force is

V _MR = −K _T ω + I _M R + V _T (2)

This voltage is applied to the motor through a transistor (not shown) in the speed reduction circuit 5, and a motor current flows. This current is fed back to the integrator 1 in the same manner as during acceleration, and when | V _MR | decreases as the rotation speed decreases due to deceleration, the output of the integrator 1 increases and the impedance of the transistor (not shown) of the speed reduction circuit 5 decreases. Control it to come down. Further, when | V _MR | decreases due to the decrease in rotation speed and the motor current cannot be held even when the transistor (not shown) in the speed reduction circuit 5 becomes saturated, the output of the integrator 1 further increases and the acceleration circuit 3 Shift to the operation of.

[0012]

[Problems to be solved by the device]

 However, in the conventional reaction wheel motor drive circuit, when switching from acceleration to deceleration, the motor output voltage generated in the acceleration circuit 3 and the motor back electromotive force generated in deceleration are added, and this voltage is applied to the motor DC resistance. There was a problem that the divided current flows as the inrush current of the motor drive circuit power supply.

[0013]

[Means for Solving the Problems]

 The reaction wheel drive circuit according to the present invention comprises an integrator that applies a torque command and integrates it, an acceleration circuit that controls the voltage required to accelerate the reaction wheel according to the integrator output, and a reaction wheel drive. A deceleration circuit that supplies a current due to a counter electromotive voltage during deceleration, a one-shot circuit that temporarily decelerates the integrator when the torque direction command changes, and a delay circuit that delays and outputs the torque direction command. A commutation circuit for receiving a torque direction command from the delay circuit and giving an instruction to switch the torque generation direction to the reaction wheel is provided.

Further, an integrator for applying a torque command to integrate the torque command, an acceleration circuit for controlling a voltage required for accelerating the reaction wheel according to the integrator output, and an inverse circuit for decelerating the reaction wheel. A deceleration circuit that supplies a current due to an electromotive voltage, a first logic circuit that determines the acceleration / deceleration of the reaction wheel by inputting a torque direction command and a rotation direction signal of the reaction wheel, and a one-shot signal when the torque direction command changes. A one-shot circuit that outputs, a second logic circuit that outputs the one-shot signal to the integrator to temporarily decelerate only when the determination of the first logic circuit is deceleration, and a torque direction command The delay circuit that delays and outputs the torque and the direction of torque generation on the reaction wheel in response to the torque direction command from the delay circuit. A commutation circuit for giving a switching instruction may be provided.

[0015]

[Action]

 The one-shot circuit temporarily decelerates the integrator whenever the torque direction command changes. On the other hand, the change of the torque direction command is delayed by the delay circuit for a predetermined time, and the timing of the back electromotive force generation is shifted by the commutation circuit. As a result, the transition from the acceleration current to the deceleration current is performed smoothly when the acceleration changes to the deceleration, and the inrush current of the power supply of the motor drive circuit is prevented.

Further, the first logic circuit determines whether the combination of the torque direction command and the rotation direction command signal of the reaction wheel is the time of re-acceleration of the reaction wheel, that is, from deceleration to acceleration. In the case of reacceleration, the second logic circuit does not pass the output of the one-shot circuit, and in the case of deceleration it receives the output of the first logic circuit and passes the output of the one-shot circuit.

[0017]

【Example】

 FIG. 1 (a) is a circuit diagram of an embodiment of a reaction wheel drive circuit according to the present invention, in which a one-shot circuit 9 and a delay circuit 10 are added to the one shown in FIG. 5 described as a conventional technique. Is. The one-shot circuit 9 inputs the torque direction command (TD), connects the output to the integrator 1, and temporarily sets the integrator 1 to a negative state, that is, a deceleration state every time the torque direction command TD changes. , The acceleration circuit 3 and the deceleration circuit 5 are turned off. The delay circuit 10 connects the torque direction command TD to the input and connects the output to the commutation circuit 6 to delay the change of the torque direction command for a predetermined time.

FIG. 2 shows a timing chart of the embodiment. When the torque direction command TD is switched, the one-shot circuit 9 turns off the acceleration circuit 3, and the delay circuit 10 delays the torque direction command TD to TD ′, thereby shifting the switching timing by the commutation circuit 6. As a result, the switching time τ occurs, and acceleration and deceleration do not immediately shift. The motor output voltage generated in the acceleration circuit 3 and the motor back electromotive force generated in deceleration are not added, and the inrush current of the motor drive circuit power supply can be made almost zero.

FIG. 1B is an embodiment for improving the delay of the acceleration operation at the time of reacceleration, and only the added portion and the portion related thereto are shown. Therefore, the portion not shown is shown in FIG. Is the same as. In the example of FIG. 1A, the one-shot circuit 9 is used to decelerate the product operation of the integrator 1 when the torque direction command TD is switched, but the one-shot circuit 9 is always used when the torque direction command TD is switched. Since it operates, the operating point of the integrator 1 is decelerated even during reacceleration (switching from deceleration to acceleration), so the delay time until acceleration is increased. Therefore, as shown in FIG. 1B, the torque direction command TD is connected to one input of the first logic circuit 11 composed of the exclusive OR circuit, and the wheel rotation direction signal SD is connected to the other input. Connecting. The output of the first logic circuit 11 is connected to one of the second logic circuits 12 formed by an AND circuit, and the output of the one-shot circuit 9, that is, the integrator is temporarily decelerated to the other input. One-shot signal is connected and gated by the output of the first logic circuit 11.

Now, when the wheel rotation direction is the counterclockwise CCW and the torque direction command TD is the clock direction CW, this is the case of reacceleration (acceleration). When the wheel rotation direction signal SD is "H" in the counterclockwise CCW and the torque direction command TD is "H" in the clockwise CW, the first logic circuit 11 is "L". Therefore, the one-shot signal of the one-shot circuit 9 can be prevented from being output to the output of the second logic circuit 12. When the wheel rotation direction is CCW CCW and the torque direction command TD is CCW CCW, it means deceleration. When the wheel rotation direction signal SD is "H" in the counterclockwise CCW and the torque direction command TD is "L" in the counterclockwise CCW, the first logic circuit 11 is "1". H ", and the one-shot signal of the one-shot circuit 9 can be output to the output of the second logic circuit 12. FIG. 3 shows the relationship between acceleration and deceleration based on the torque direction command TD and the rotation direction signal SD. In the above example, the case where the lower rotation direction in FIG. 3 is the counterclockwise CCW has been described. In this way, in the case of deceleration, the one-shot signal can be output to prevent the inrush current as in the first embodiment, and in the case of acceleration, the one-shot signal is not output and the operating point of the integrator 1 Can move to acceleration operation without delay.

[0021]

[Effect of the device]

 As described above, according to the present invention, it is possible to eliminate the inrush current during deceleration and to reduce the delay in operation during reacceleration.

[Brief description of drawings]

1A is a circuit diagram of one embodiment of the present invention, and FIG. 1B is a circuit diagram illustrating another embodiment.

FIG. 2 is a timing chart of the embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between acceleration and deceleration based on a torque direction command TD and a rotation direction signal SD.

FIG. 4 is a diagram illustrating the principle of attitude control.

FIG. 5 is a circuit diagram of an example of a conventional reaction wheel drive circuit.

[Explanation of symbols]

 1 integrator 3 acceleration circuit 4 reaction wheel 5 deceleration circuit 6 commutation circuit 9 one-shot circuit 10 delay circuit 11 first logic circuit 12 second logic circuit

Claims (2)

[Scope of utility model registration request] 1. A reaction wheel drive circuit used for attitude control, including an integrator for applying a torque command to integrate the torque command, and an acceleration circuit for controlling a voltage required for accelerating the reaction wheel according to an integrator output.
A deceleration circuit that supplies current due to back electromotive force during deceleration of the reaction wheel, a one-shot circuit that temporarily decelerates the integrator when the torque direction command changes, and a delay that delays and outputs the torque direction command. A drive circuit for a reaction wheel, comprising: a circuit; and a commutation circuit that receives a torque direction command from the delay circuit and gives a command to the reaction wheel to switch the torque generation direction. 2. A reaction wheel drive circuit used for attitude control, comprising an integrator for applying a torque command to integrate the torque command, and an acceleration circuit for controlling a voltage required for accelerating the reaction wheel according to an integrator output.
A deceleration circuit that supplies a current due to a back electromotive force during deceleration of the reaction wheel, a first logic circuit that determines the acceleration / deceleration of the reaction wheel by inputting a torque direction command and a rotation direction signal of the reaction wheel, and a torque direction command And a one-shot circuit that outputs a one-shot signal at the time of change, and a second-shot circuit that outputs the one-shot signal to the integrator only when the determination by the first logic circuit is deceleration to temporarily decelerate. A logic circuit, a delay circuit that delays and outputs a torque direction command, and a commutation circuit that receives a torque direction command from the delay circuit and gives a command to the reaction wheel to switch the torque generation direction, Reaction wheel drive circuit.