A self-neutralizing device for ionic liquid thruster

Abstract

The invention discloses a self-neutralization device for an ionic liquid thruster, which is realized by feedback circuit control. The feedback circuit is composed of a high-voltage isolation circuit, a sampling circuit, a control circuit, a storage capacitor, an isolation resistor, etc. The accumulated charge is limited between the thruster and the high-voltage output end by the high-voltage isolation circuit, and the charge is captured by the storage capacitor and converted into a voltage signal at both ends of the capacitor. The sampling circuit measures the capacitor voltage by a voltage division method and transmits it to the control circuit. The high-voltage isolation circuit changes the voltage value or duty cycle of the output signal under the regulation of the control circuit, so that the positive and negative ion emission ratio of the thruster beam is changed to balance the originally accumulated charge amount. The device of the invention can autonomously balance the positive and negative ion emission ratio of the ionic liquid thruster and maintain the self-neutralization work of the thruster, prevent the spacecraft from being charged due to charge accumulation, avoid the electrochemical reaction of the ionic liquid caused by charge imbalance, and significantly improve the working life of the ionic liquid thruster.

Description

Technical Field

[0001] The invention belongs to the technical field of electric propulsion thruster design, and in particular relates to a self-neutralization device of an ionic liquid thruster. Background Art

[0002] Electric propulsion is an advanced propulsion technology that uses electric energy to directly heat or dissociate and accelerate the working fluid to form a high-speed jet to obtain thrust. It has high specific impulse and thrust, and has broad application prospects in space missions such as spacecraft attitude adjustment, orbit control, deep space exploration, and interstellar navigation.

[0003] Ionic liquid thrusters are a type of electric propulsion that uses a strong electric field to form a Taylor cone on the emitter surface, thereby drawing out charged droplets or ions and accelerating them under the action of the electric field to generate thrust. Ionic liquid thrusters passively supply propellant through the capillary mechanism, are easy to miniaturize and array, and are one of the best propulsion solutions for attitude and orbit control of micro-nano spacecraft.

[0004] Unlike traditional electric propulsion devices that use inert gas or metal working fluids, ionic liquid thrusters can not only emit positive ions, but also change the polarity of applied voltage to extract negative ions. During operation, ionic liquid thrusters often use alternating positive and negative high voltages to periodically extract positive and negative charges in the ionic liquid, thereby maintaining the charge balance in the plume and the ionic liquid to achieve self-neutralization, while avoiding the impact of the electrochemical reaction of the ionic liquid on the life of the thruster. In actual situations, the emission of positive and negative ions by ionic liquid thrusters are two independent processes, which are affected by complex factors such as emission voltage, signal noise, and the properties of ionic liquids. Therefore, the thruster cannot ensure that the emitted positive and negative ion currents are exactly the same through fixed working parameters, which ultimately leads to charging problems in the ionic liquid and the spacecraft. In this case, it is necessary to introduce dynamic working parameters to adjust the emission of positive and negative ion beams of ionic liquid thrusters in real time in order to truly achieve self-neutralization emission of ionic liquid thrusters. Summary of the invention

[0005] In order to solve the deficiencies of the above-mentioned prior art, the present invention proposes a self-neutralization device for an ionic liquid thruster, which performs feedback regulation on the positive and negative ion emission currents of the ionic liquid thruster, realizes the self-neutralization and stable operation of the thruster, ensures the safe and reliable operation of the thruster, prolongs the working time and service life of the thruster, and minimizes the impact of charge imbalance on the thruster and the spacecraft. The specific technical solutions of the present invention are as follows:

[0006] A self-neutralizing device for an ionic liquid thruster comprises a high-voltage isolation circuit, a control circuit, a sampling circuit, an isolation resistor, a storage capacitor and a thruster, wherein:

[0007] The thruster comprises a thruster absorption electrode, a thruster emission electrode, an ionic liquid tank, an electrode and a thruster casing;

[0008] The high-voltage isolation circuit converts the low-voltage DC signal input by the external input positive electrode into a square wave signal with positive and negative high voltages changing alternately, and outputs it from the high-voltage output positive electrode. The external input ground of the high-voltage isolation circuit is isolated from the high-voltage output ground; the high-voltage output positive electrode and the high-voltage output ground are respectively connected to the thruster emitter and the thruster absorption electrode. The thruster forms an ion beam flow with positive and negative alternating emissions and generates thrust under the drive of the positive and negative high voltages;

[0009] The storage capacitor and the isolation resistor are arranged in parallel between the high-voltage output ground and the external input ground, and the storage capacitor obtains the high-voltage end charge accumulation generated by the thruster positive and negative ion unbalanced emission and forms a voltage signal at both ends of the storage capacitor;

[0010] The sampling circuit is connected to the control circuit and arranged between the isolation resistor and the high-voltage isolation circuit to collect signals and adjust the high-voltage output signal of the high-voltage isolation circuit to change the thruster beam emission state, and finally balance the accumulated charge amount to achieve thruster self-neutralization;

[0011] The sampling circuit measures the voltage of the isolation resistor to obtain the voltage parameters at both ends of the storage capacitor and imports them into the control circuit for calculation and analysis. Finally, the control circuit adjusts the high-voltage output positive electrode of the high-voltage isolation circuit according to the analysis results.

[0012] Furthermore, the isolation resistance is above 100 megohms.

[0013] Furthermore, the control circuit adjusts the output voltage value and duty cycle of the high-voltage isolation circuit based on the voltage signal of the storage capacitor.

[0014] Further, the self-neutralization method based on the self-neutralization device is:

[0015] The power of the whole device is provided by the external input signal of the external input positive electrode input, which is converted by the high-voltage isolation circuit into an initial high-voltage output signal that alternates between positive and negative and drives the thruster to emit positive and negative ion beams;

[0016] When the positive and negative ion beams are in an unbalanced state, charge accumulation will appear at one end of the storage capacitor; if the proportion of positive ions in the positive and negative ion beams is higher than that of negative ions, the charge accumulation is negative, otherwise it is positive;

[0017] The accumulated charge is sensed by the storage capacitor to form a capacitor voltage at both ends thereof, and the polarity of the capacitor voltage is related to the accumulated charge;

[0018] The sampling circuit obtains the capacitor voltage through voltage division measurement and transmits it to the control circuit, and the control circuit analyzes the capacitor voltage and gives the output voltage and duty cycle adjustment amount to regulate the high-voltage output signal; if the charge accumulation amount is negative, the negative high-voltage value in the high-voltage output signal is increased or the negative high-voltage duty cycle is increased, which will increase the proportion of negative ion jets in the positive and negative ion beams and thus balance the negative polarity charge accumulation in the circuit;

[0019] By repeating the above feedback control process, the ionic liquid thruster is always in a state of balanced emission of positive and negative ion currents and achieves a self-neutralizing working mode, thereby extending the service life of the thruster and avoiding charging of the spacecraft.

[0020] The beneficial effects of the present invention are:

[0021] 1. High-voltage isolation design: Compared with the method of sharing the ground between the ionic liquid thruster's absorption pole and the spacecraft, the isolated output method limits the accumulation of charge to the power output end and the thruster, thereby reducing the impact of the thruster's operation on the spacecraft's charging.

[0022] 2. Capacitive power storage design: In the isolated state, the equivalent capacitance between the output and input ends of the circuit is very small, and the charge accumulation will cause the thruster potential to fluctuate greatly in an instant; the introduction of the power storage capacitor can effectively slow down the charging speed, which makes circuit feedback control possible.

[0023] 3. Self-neutralization feedback control: The self-neutralization of the ionic liquid thruster is achieved through the feedback control method, so that the thruster can operate independently without a neutralizer.

[0024] 4. Extend the life of the thruster: The realization of self-neutralization allows the ionic liquid in the thruster tank to maintain a charge balance state, which can avoid the electrochemical reaction of the ionic liquid and thus extend the life of the thruster. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. By referring to the drawings, the features and advantages of the present invention will be more clearly understood. The drawings are schematic and should not be understood as limiting the present invention in any way. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0026] Figure 1 This is a diagram of an ionic liquid thruster and a self-neutralization device;

[0027] Figure 2 This is the self-neutralization principle diagram of the ionic liquid thruster;

[0028] Figure 3 It is the principle of voltage division measurement;

[0029] Figure 4 This is the PWM control principle.

[0030] Description of Figure Numbers:

[0031] 1-high voltage isolation circuit, 2-external input ground, 3-external input positive electrode, 4-high voltage output ground, 5-control circuit, 6-sampling circuit, 7-isolation resistor, 8-storage capacitor, 9-thruster absorption electrode, 10-thruster emitter, 11-ionic liquid tank, 12-electrode, 13-thruster housing, 14-high voltage output positive electrode;

[0032] 201-external input signal, 202-high voltage output signal, 203-positive and negative ion beam current, 204-charge accumulation amount, 205-capacitor voltage, 206-output voltage, duty cycle adjustment amount. DETAILED DESCRIPTION

[0033] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0035] The working principle of the device of the present invention is as follows: during the working process, the thruster emits positive and negative ions alternately under the action of positive and negative high voltages, so that the output end of the circuit accumulates positive and negative charges periodically; when the positive and negative charge emission ratio is unbalanced, the two ends of the storage capacitor gradually accumulate charges and form a potential difference, and the voltage signal can be obtained by measuring the voltage division of the isolation resistor 7 through the sampling circuit 6; in the control circuit 5, this signal is compared and analyzed, and the positive and negative voltage values ​​or the positive and negative voltage duty ratios of the high-voltage output signal are changed according to the analysis results, so that the positive and negative ion emission ratio can be adjusted to eliminate the charges accumulated at both ends of the storage capacitor; repeated sampling and control links can make the thruster enter a stable self-neutralizing working state. The capacitance of the storage capacitor 8 determines the storage capacity and boost speed of the capacitor. A capacitor with a larger capacitance is more conducive to the feedback adjustment of the circuit. In addition, the isolation resistor should be above the order of 100 megohms to reduce interference with the storage process.

[0036] Specifically, Figure 1As shown, a self-neutralization device for an ionic liquid thruster includes a high-voltage isolation circuit 1, a control circuit 5, a sampling circuit 6, an isolation resistor 7, a storage capacitor 8 and a thruster, wherein:

[0037] The thruster comprises a thruster suction pole 9, a thruster emitter 10, an ionic liquid tank 11, an electrode 12 and a thruster casing 13;

[0038] The high-voltage isolation circuit 1 converts the low-voltage DC signal input by the external input positive electrode 3 into a square wave signal with alternating positive and negative high voltages, and outputs it from the high-voltage output positive electrode 14. The external input ground 2 of the high-voltage isolation circuit 1 is isolated from the high-voltage output ground 4, so that the charge accumulation caused by the operation of the thruster is confined to the thruster without affecting the spacecraft; the high-voltage output positive electrode 14 and the high-voltage output ground 4 are respectively connected to the thruster emitter 10 and the thruster absorption electrode 9, and the thruster forms an ion beam flow with alternating positive and negative emissions under the drive of the positive and negative high voltages and generates thrust;

[0039] The storage capacitor 8 and the isolation resistor 7 are connected in parallel between the high-voltage output ground 4 and the external input ground 2. The storage capacitor 8 obtains the high-voltage end charge accumulation generated by the thruster positive and negative ion unbalanced emission and forms a voltage signal at both ends of the storage capacitor 8.

[0040] The sampling circuit 6 is connected to the control circuit 5 and is arranged between the isolation resistor 7 and the high-voltage isolation circuit 1 to collect signals and adjust the high-voltage output signal of the high-voltage isolation circuit 1 to change the thruster beam emission state, and finally balance the accumulated charge amount to achieve thruster self-neutralization;

[0041] The sampling circuit 6 uses a voltage division measurement method to obtain the voltage signal at both ends of the storage capacitor 8. The voltage division measurement method is a more common voltage measurement method. The measurement principle is as follows: Figure 3 As shown, the isolation resistor 7 is connected in series with the sampling resistor, and the voltage V across the capacitor C Calculated by the following formula: Among them, R iso is the resistance of the isolation resistor, R sam is the resistance of the sampling resistor, V sam The obtained voltage parameter is introduced into the control circuit 5 for calculation and analysis, and finally the control circuit 5 adjusts the high voltage output positive electrode 14 of the high voltage isolation circuit 1 according to the analysis result. Taking the duty cycle adjustment method as an example, the control circuit can use a PWM circuit to generate a pulse width modulation signal. The circuit principle is as follows Figure 4 As shown, Figure 4The PWM circuit can be realized by integrated circuits such as JF1525, and the duty cycle of the output pulse width modulation signal of the PWM circuit changes with the signal from the error amplifier. This pulse width modulation signal is used as a control signal for the polarity conversion part in the high-voltage isolation circuit 1, which can change the duty cycle of the high-voltage output signal and thus change the proportion of the positive and negative ion emission current of the thruster, thereby realizing feedback control of the thruster's self-neutralization operation.

[0042] In some embodiments, the high-voltage isolation circuit 1 can be decomposed into three parts: isolated power supply, boost and polarity switching. The isolated power supply is completed by the isolator; the boost circuit converts the DC external input signal commonly used in spacecraft into the high-voltage output signal required for the operation of the thruster. The basic process is: high-frequency oscillation generates low-voltage pulses-the pulse transformer boosts the voltage to a predetermined voltage value-pulse rectification obtains high-voltage DC power; the polarity switching uses a switch tube to achieve the switching of positive and negative polarity high voltage. Taking duty cycle control as an example, the switching process can control the conduction and cutoff of the switch tube by inputting a pulse width modulation signal, thereby controlling the duty cycle of the high-voltage output signal.

[0043] Preferably, the isolation resistor 7 is greater than 100 megohms to avoid the transfer of charge.

[0044] In some implementations, the control circuit 5 adjusts the output voltage value and duty cycle of the high-voltage isolation circuit 1 based on the voltage signal of the storage capacitor 8 .

[0045] In some embodiments, the self-neutralization method based on the above self-neutralization device is:

[0046] The power of the whole device is provided by an external input signal 201 inputted by an external input positive electrode 3, which is converted into an initial high voltage output signal 202 which changes alternately between positive and negative by a high voltage isolation circuit 1 and drives the thruster to emit positive and negative ion beams 203;

[0047] When the positive and negative ion beams 203 are in an unbalanced state, a charge accumulation 204 will appear at one end of the storage capacitor 8; if the proportion of positive ions in the positive and negative ion beams 203 is higher than that of negative ions, the charge accumulation 204 is negative, otherwise it is positive;

[0048] The charge accumulation amount 204 is sensed by the storage capacitor 8 and a capacitor voltage 205 is formed at both ends thereof, and the polarity of the capacitor voltage is related to the charge accumulation amount;

[0049] The sampling circuit 6 obtains the capacitor voltage 205 through voltage division measurement and transmits it to the control circuit 5. The control circuit 5 analyzes the capacitor voltage 205 and provides the output voltage and the duty cycle adjustment amount 206 to regulate the high voltage output signal 202. If the charge accumulation amount is negative, the negative high voltage value in the high voltage output signal 202 is increased or the negative high voltage duty cycle is increased, which will increase the proportion of negative ion jets in the positive and negative ion beams 203 and balance the negative polarity charge accumulation in the circuit.

[0050] By repeating the above feedback control process, the ionic liquid thruster is always in a state of balanced emission of positive and negative ion currents and achieves a self-neutralizing working mode, thereby extending the service life of the thruster and avoiding charging of the spacecraft.

[0051] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A self-neutralization device for an ionic liquid thruster, characterized in that: It comprises a high-voltage isolation circuit (1), a control circuit (5), a sampling circuit (6), an isolation resistor (7), a storage capacitor (8) and a thruster, wherein: The thruster comprises a thruster absorption electrode (9), a thruster emission electrode (10), an ionic liquid tank (11), an electrode (12) and a thruster casing (13); The high-voltage isolation circuit (1) converts a low-voltage direct current signal inputted by an external input positive electrode (3) into a square wave signal with positive and negative high voltages changing alternately, and outputs the signal through a high-voltage output positive electrode (14); the external input ground (2) of the high-voltage isolation circuit (1) is isolated from the high-voltage output ground (4); the high-voltage output positive electrode (14) and the high-voltage output ground (4) are respectively connected to the thruster emitter (10) and the thruster absorber (9); the thruster forms an ion beam flow with positive and negative alternating emissions and generates thrust under the drive of the positive and negative high voltages; The storage capacitor (8) and the isolation resistor (7) are arranged in parallel between the high-voltage output ground (4) and the external input ground (2), and the storage capacitor (8) obtains the high-voltage end charge accumulation generated by the thruster positive and negative ion unbalanced emission and forms a voltage signal at both ends of the storage capacitor (8); The sampling circuit (6) is connected to the control circuit (5) and arranged between the isolation resistor (7) and the high-voltage isolation circuit (1), and performs signal acquisition and adjusts the high-voltage output signal of the high-voltage isolation circuit (1) to thereby change the thruster beam emission state, and finally balance the accumulated charge amount to achieve thruster self-neutralization; The sampling circuit (6) performs voltage division measurement on the isolation resistor (7) to obtain voltage parameters at both ends of the storage capacitor (8) and imports the voltage parameters into the control circuit (5) for calculation and analysis. Finally, the control circuit (5) adjusts the high-voltage output positive electrode (14) of the high-voltage isolation circuit (1) according to the analysis results.

2. The self-neutralization device according to claim 1, characterized in that: The isolation resistor (7) is above 100 megohms.

3. The self-neutralization device according to claim 1 or 2, characterized in that: The control circuit (5) adjusts the output voltage value and duty cycle of the high-voltage isolation circuit (1) based on the voltage signal of the storage capacitor (8).

4. The self-neutralization method of the self-neutralization device according to any one of claims 1 to 3, characterized in that: The specific implementation process of the method is: The power of the entire device is provided by an external input signal (201) input by the external input positive electrode (3), which is converted by the high-voltage isolation circuit (1) into an initial high-voltage output signal (202) that alternates between positive and negative and drives the thruster to emit positive and negative ion beams (203); When the positive and negative ion beams (203) are in an unbalanced state, a charge accumulation amount (204) will appear at one end of the storage capacitor (8); if the proportion of positive ions in the positive and negative ion beams (203) is higher than that of negative ions, the charge accumulation amount (204) is negative, otherwise it is positive; The charge accumulation amount (204) is sensed by the storage capacitor (8) to form a capacitor voltage (205) at both ends thereof, and the polarity of the capacitor voltage is related to the charge accumulation amount; The sampling circuit (6) obtains the capacitor voltage (205) through voltage division measurement and transmits it to the control circuit (5); the control circuit (5) analyzes the capacitor voltage (205) and provides an output voltage and a duty cycle adjustment amount (206) to regulate the high-voltage output signal (202); if the charge accumulation amount is negative, the negative high-voltage value in the high-voltage output signal (202) is increased or the negative high-voltage duty cycle is increased, so as to increase the proportion of negative ion jets in the positive and negative ion beams (203) and thus balance the negative polarity charge accumulation in the circuit; By repeating the above feedback control process, the ionic liquid thruster is always in a state of balanced emission of positive and negative ion currents and achieves a self-neutralizing working mode, thereby extending the service life of the thruster and avoiding charging of the spacecraft.

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