Magnetic torquer drive circuit based on constant current source
Technical Field
The invention relates to a magnetic torquer driving circuit based on a constant current source, which is applied to a hundred-kilogram-level commercial small satellite, and belongs to the technical field of satellite electronics.
Background
The magnetic torquer is an important component of a satellite attitude control subsystem, and is mainly used for powering up a satellite after separation of a satellite and an arrow, generating magnetic force through a geomagnetic field, reducing the separation angular velocity of the satellite, and enabling the rotation of the satellite to be controlled within a certain range or used for maintaining the attitude of the satellite after the satellite is in orbit for a long time.
The existing magnetic torquer driving circuit generally adopts an H-bridge circuit built by MOS (metal oxide semiconductor) tubes, and controls the on-off of voltages at two ends of the H-bridge circuit by controlling the on-off state of the H-bridge circuit so as to adjust the on-off time (PWM (pulse width modulation)) of the MOS tubes to control the current of the magnetic torquer and further control the magnetic moment.
The driving circuit adopted by the prior art at present has the following defects: firstly, the magnitude of the output current cannot be accurately controlled; secondly, the control algorithm is complex and cannot effectively inhibit oscillation of the output magnetic moment due to the influence of the charging and discharging time, so that the realization of the attitude control function is directly influenced, and a great risk is brought to the attitude control of the whole satellite; thirdly, the existing driving circuit usually has no feedback circuit, and the open-loop control mode obviously brings inconvenience to control output.
In view of this, the present patent application is specifically proposed.
Disclosure of Invention
The application the magnetic torquer drive circuit based on the constant current source is characterized in that the problem existing in the prior art is solved, the drive circuit design capable of accurately controlling the output current is provided, the output voltage of a DA chip generates the magnetic torquer current capable of being quantitatively controlled, and the actual control effect is monitored on the basis of providing a closed loop feedback circuit, so that the design purpose of simple control, high reliability and high safety is realized.
In order to achieve the above design objective, the magnetic torquer driving circuit based on the constant current source mainly comprises:
the processor is used for driving the DA chip to generate constant current source driving voltage;
the DA chip is used for generating voltage required by the rear-end operational amplifier output;
the AD chip is used for collecting voltage generated when the driving current flows through the feedback resistor;
the operational amplifier chip is used for generating voltage and current required by the amplification of the triode;
the triode is used for amplifying current and driving the magnetic torquer;
the diode and the bleeder resistor are connected in series and used for discharging the reverse electromotive force of the magnetic torquer;
the feedback resistor is used for completing current-voltage conversion;
the processor is connected with a control signal end of the DA chip to control the output of the DA chip, and an output end of the DA chip is connected with a positive input end of the operational amplifier chip; the output end of the operational amplifier chip is connected with the base electrode of the triode, the emitter electrode of the triode is connected with the negative input end of the operational amplifier chip and is simultaneously connected with the input end of the AD chip, and then the operational amplifier chip is grounded through the feedback resistor; and the collector of the triode is connected with a diode and a bleeder resistor which are connected in series, and the bleeder resistor is connected with a power supply end of the magnetic torquer.
Further, in order to solve the problem of use failure in the space use environment, the feedback resistor comprises a first feedback resistor and a second feedback resistor which are connected in parallel, so that the reliability of the system is improved.
In summary, the magnetic torquer driving circuit based on the constant current source has the following advantages and beneficial effects:
1. compare with current PWM pulsed drive mode, this application provides a closed loop feedback circuit, can monitor actual control effect, and the circuit calculation value is shown with the following table 1 of measured value.
2. The driving circuit is simple, the driving capability of the magnetic torquer is no longer related to the magnetic torquer, and the power supply voltage does not need to be calculated and corrected, so that the universal driving circuit has high universality and simplifies the design flow.
3. The attitude control algorithm is simpler, and the required current and control time can be calculated by directly utilizing the known magnetic field and the known angular velocity to implement control.
4. The magnetic moment oscillation generated by the circuit is remarkably reduced without frequent switching, and the reverse electromotive force bleeder circuit in the circuit provides effective protection and higher reliability for the front-end driving circuit.
Drawings
The following drawings are illustrative of specific embodiments of the present application.
FIG. 1 is a schematic diagram of a driving circuit of a magnetic torquer based on a constant current source;
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings.
Embodiment 1, as shown in fig. 1, a magnetic torquer driving circuit based on a constant current source mainly includes:
the processor D1 is used for driving the DA chip to generate a constant current source driving voltage;
the DA chip D2 is used for generating voltage required by the rear-end operational amplifier output;
the AD chip D3 is used for collecting the voltage generated by the driving current flowing through the feedback resistors R2 and R3;
the operational amplifier chip D4 is used for generating voltage and current required by triode amplification;
the triode V2 is used for amplifying current and driving the magnetic torquer;
the diode V1 and the bleeder resistor R1 are connected in series and used for bleeding the back electromotive force of the magnetic torquer;
the feedback resistor is used for completing current-voltage conversion; considering that the resistor is easy to fail in the space use environment, two resistors are connected in parallel to improve the system reliability, namely a first feedback resistor R2 and a second feedback resistor R3 which are connected in parallel;
the processor D1 is connected with the control signal end of the DA chip D2 to control the output of the DA chip D2, and the output end of the DA chip D2 is connected with the positive input end of the operational amplifier chip D4; the output end of the operational amplifier chip D4 is connected with the base electrode of the triode V2, the emitter of the triode V2 is connected with the negative input end of the operational amplifier chip D4, and is simultaneously connected with the input end of the AD chip D3, and then is grounded through feedback resistors (R2 and R3 which are connected in parallel); the collector of the triode V2 is connected with a diode V1 and a bleeder resistor R1 which are connected in series, and the bleeder resistor R1 is connected with a power supply end of the magnetic torquer; the magnetor H1 is connected between the power supply terminal of the magnetor and the collector of the transistor V2.
By applying the design of the driving circuit, the control flow of the magnetic torquer H1 is that the processor D1 controls the output voltage of the DA chip D2, the output voltage is connected to the bases of the operational amplifier chip D4 and the triode V2, and the collector current output of the triode V2 can be accurately controlled by adjusting the output voltage of the DA chip D2 and the base voltage of the triode V2, so that the accurate control of the current of the magnetic torquer H1 is realized.
Specifically, the current required for controlling the magnetic torquer H1 is set to I, the output voltage of the DA chip D2 is controlled to V by the processor D1, and the total resistance of the resistor connected to the emitter of the triode V2 is set to R, so that the following relationships exist: and I is V/R.
The control process is as follows: the current required by posture damping after the separation of the star and the arrow is I0, and the time is t, then the processor D1 controls the output voltage of the DA chip D2 to be:
starting an internal timer, and finely adjusting the output of the DA chip according to the acquisition value of the feedback voltage at the D3 end of the AD chip; if the acquisition value of the AD chip D3 is V1, then when the actual driving current value I of the magnetic torquer H1 is in relation to V1:
if I > I0, the voltage output by the DA chip D2 is reduced by the processor D1; otherwise, the voltage output by the DA chip D2 is increased.
And the difference value between the I and the I0 is determined by a whole-satellite control strategy in which range the voltage needs to be adjusted, after the time reaches t, the output of the DA chip D2 is closed to complete a control period, and finally, the next calculation and control are carried out according to the current attitude output by the satellite attitude sensor.
As shown in the following table, the operational amplifier chip D4 may be selectively LM124, and the transistor V2 may be selectively 2N2222, for example, the comparison between the theoretical calculated value and the measured value of the driving current is performed.
TABLE 1 comparison of theoretical values with actual test data
The actual measurement result shows that the driving current range of the magnetic torquer H1 is 0-105mA, the actual measurement value of the circuit is consistent with the theoretical calculation value, and the performance is good in the practical application process.
In summary, the embodiments presented in connection with the figures are only preferred. Those skilled in the art can derive other alternative structures according to the design concept of the present invention, and the alternative structures should also fall within the scope of the solution of the present invention.