Excitation power supply device and method for Hall thruster

Abstract

The invention discloses an excitation power supply device and method of a Hall thruster, and relates to the technical field of Hall thrusters, the device comprises a discharge power supply, a filtering unit and an excitation unit, one end of the excitation unit and a first end of the filtering unit are both connected with a negative electrode of the discharge power supply, the negative electrode of the discharge power supply is grounded, and the first end of the filtering unit is grounded. The other end of the excitation unit is connected with the cathode of the Hall thruster, and the excitation unit is used for providing excitation voltage; the second end of the filtering unit is connected with the anode of the Hall thruster, and the third end of the filtering unit is connected with the anode of the discharge power supply. According to the invention, the requirement on ignition starting parameters when the Hall thruster is ignited and started can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of Hall thrusters, and particularly to an excitation power supply device and method for a Hall thruster. Background Art

[0002] A Hall thruster is a thrust device that converts electrical energy into the kinetic energy of a working fluid by the action of mutually perpendicular electric and magnetic fields, and is one of the most widely used electric thrusters in space propulsion. Its ignition process is to wait for the cathode to be heated to a certain temperature, then apply a high voltage to the keeper electrode of the cathode to extract electrons, forming a high electron density in the exit area. These electrons enter the discharge channel and undergo an ionization avalanche process with neutral gas molecules to successfully ignite the Hall thruster. The engineering criterion for successful ignition of a Hall thruster is generally that the discharge current is greater than a certain value (e.g., 0.5 A) for 3 - 5 seconds, which is considered a successful ignition. The ignition start parameters include the excitation current, discharge voltage, neutral gas flow rate, and ignition voltage. Among them, the magnitude of the excitation current affects the magnetic field strength of the Hall thruster, the discharge voltage is to establish an electric field in the channel from the anode of the Hall thruster to the cathode of the Hall thruster, and the ignition voltage is actually to instantaneously pull out electrons from the cathode of the Hall thruster. The higher the voltage, the more electrons are pulled out and the greater the energy, which is also beneficial for ignition start.

[0003] In the existing ignition methods, to ensure that the discharge current is controlled within a reasonable range during the startup process, it is generally necessary to supply power to the excitation coil in advance to establish the magnetic field in the channel. As Figure 1 shown, a traditional Hall thruster requires a separate excitation power supply to supply power to the excitation coil. When starting the Hall thruster, the discharge power supply and the excitation power supply are started simultaneously. Under the combined action of the magnetic field and the electric field, electrons enter the discharge channel. Since the cathode is outside the discharge channel and there is an anode connected to the positive pole of the discharge power supply in the channel, the electrons will move towards the high potential and will be restricted by the magnetic field formed by the excitation coil during this process. Therefore, to facilitate ignition start, the discharge voltage will be relatively large and the excitation current will generally be relatively small. After successful ignition start in this state, the discharge current is relatively large compared to the rated current, which may cause the power to exceed the limit and trigger the protection action of the power supply bus, shutting down the entire system; if the excitation current is increased, the magnetic field resistance on the electrons during the ignition stage will increase, which will also increase the difficulty of ignition. In summary, there are problems in the prior art that the ignition start parameters required for the ignition start of a Hall thruster are relatively high and the ignition difficulty is great. Summary of the Invention

[0004] The object of the present invention is to provide an excitation power supply device and method for a Hall thruster, which can reduce the requirements for ignition start parameters during the ignition start of the Hall thruster.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] In a first aspect, an excitation power supply device for a Hall thruster is provided. The device includes: a discharge power supply, a filtering unit, and an excitation unit;

[0007] One end of the excitation unit and the first end of the filtering unit are both connected to the negative electrode of the discharge power supply. The negative electrode of the discharge power supply is grounded. The other end of the excitation unit is connected to the cathode of the Hall thruster. The excitation unit is used to provide an excitation voltage;

[0008] The second end of the filtering unit is connected to the anode of the Hall thruster, and the third end of the filtering unit is connected to the positive electrode of the discharge power supply.

[0009] Further, the excitation unit includes an excitation coil, an excitation capacitor, a diode, and an excitation power supply;

[0010] One end after the excitation coil and the excitation capacitor are connected in parallel is respectively connected to the negative electrode of the diode and the cathode of the Hall thruster; the positive electrode of the diode is connected to the positive electrode of the excitation power supply; the other end after the excitation coil and the excitation capacitor are connected in parallel is connected to the cathode of the excitation power supply; the excitation power supply is used to provide an excitation voltage to pass an excitation current into the excitation coil to adjust the magnetic field strength of the Hall thruster.

[0011] Further, it is characterized in that the filtering unit includes a filtering capacitor and a filtering coil;

[0012] One end of the filtering capacitor and one end of the excitation unit are both connected to the negative electrode of the discharge power supply;

[0013] The other end of the filtering capacitor is respectively connected to one end of the filtering coil and the anode of the Hall thruster;

[0014] The other end of the filtering coil is connected to the positive electrode of the discharge power supply.

[0015] In a second aspect, an excitation power supply method for a Hall thruster is provided. The method includes:

[0016] After the cathode of the Hall thruster is heated to a preset temperature, the discharge power supply is turned on, and the excitation power supply in the excitation unit is turned off, and the Hall thruster starts to ignite;

[0017] After the Hall thruster ignites successfully, the excitation power supply in the excitation unit is turned on, and the excitation power supply provides an excitation voltage to adjust the magnetic field strength of the Hall thruster.

[0018] Further, the turning on the discharge power supply and the Hall thruster starting to ignite specifically includes:

[0019] After the discharge power supply is turned on, a voltage is applied to the anode of the Hall thruster to successfully ignite the Hall thruster.

[0020] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0021] The present invention connects the excitation unit to the loop where the Hall thruster, the filtering unit, and the discharge power supply are located. When starting up, the discharge power supply is turned on to provide a voltage for the anode of the Hall thruster for ignition startup. At this time, the excitation unit does not provide an excitation voltage, and there is no magnetic field generated by the power supply of the excitation unit in the channel of the Hall thruster. There is no resistance generated by the magnetic field during the process of electrons from the cathode to the anode. Therefore, the parameter values required for ignition startup are relatively small, thereby reducing the requirements for ignition startup parameters when the Hall thruster is ignited and started. After the Hall thruster is successfully started, the excitation unit provides an excitation voltage to provide a stable magnetic field for the Hall thruster. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 The circuit diagram for the excitation power supply of the Hall thruster in the related art;

[0024] Figure 2 The circuit diagram for the excitation power supply of the Hall thruster provided in Embodiment 1 of the present invention;

[0025] Figure 3 The flowchart of the method for the excitation power supply of the Hall thruster. Detailed Embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] The purpose of the present invention is to provide an excitation power supply device for a Hall thruster, aiming to reduce the requirements for ignition startup parameters when the Hall thruster is ignited and started.

[0028] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0029] Example 1

[0030] like Figure 2 As shown, this embodiment provides an excitation power supply device for a Hall thruster, which includes a discharge power supply U d , filter unit 1 and excitation unit 2. One end of the excitation unit 2 and the first end of the filter unit 1 are both connected to the discharge power supply U d The negative pole of the discharge power supply U d The negative pole of the filter unit 1 is grounded. The other end of the excitation unit 2 is connected to the cathode of the Hall thruster 3, and the excitation unit 2 is used to provide excitation voltage. The second end of the filter unit 1 is connected to the anode of the Hall thruster 3, and the third end of the filter unit 1 is connected to the discharge power supply U d positive connection.

[0031] In this embodiment, the filter unit 1 includes a filter capacitor C and a filter coil L1; one end of the filter capacitor C and one end of the excitation unit 2 are both connected to the discharge power supply U d The other end of the filter capacitor C is connected to one end of the filter coil L1 and the anode of the Hall thruster 3; the other end of the filter coil L1 is connected to the discharge power supply U d positive connection.

[0032] In this embodiment, the excitation unit 2 includes an excitation coil L2, an excitation capacitor Cs, a diode Ds, and an excitation power supply Us. One end of the excitation coil L2 connected in parallel with the excitation capacitor Cs is connected to the cathode of the diode Ds and the cathode of the Hall thruster 3, respectively. The anode of the diode Ds is connected to the positive electrode of the excitation power supply Us. The other end of the excitation coil L2 connected in parallel with the excitation capacitor Cs is connected to the cathode of the excitation power supply Us. The excitation power supply Us is used to provide an excitation voltage to flow an excitation current into the excitation coil L2, thereby adjusting the magnetic field strength of the Hall thruster 3.

[0033] During the ignition startup phase and the process of ignition successfully entering the discharge operation, the discharge power supply U d The filter coil L1 in filter unit 1, the anode and cathode of the Hall thruster, and the excitation coil L2 in excitation unit 2 form a discharge circuit. Diode Ds prevents the current in the discharge circuit, or the discharge current, from entering the excitation power supply Us during the ignition startup phase and discharge operation. This current is restricted to the branch containing the excitation coil L2 and excitation capacitor Cs, thus protecting the excitation power supply Us.

[0034] During the ignition phase and after successful ignition, the Hall thruster is powered by the discharge power supply U dIt operates under DC power supply. When the magnetic field and the electric field act together, oscillation of the discharge current will occur. Specifically, since the cathode of the Hall thruster is outside the discharge channel and there is an anode of the Hall thruster connected to the positive pole of the discharge power supply inside the channel, electrons will move towards the high potential. During this process, the electrons will be constrained by the magnetic field formed by the excitation coil, thus forming oscillation of the discharge current. During the experiment, it is observed that the oscillation frequency range of the discharge current is about 20 - 40 kHz. The oscillation of the discharge current relative to the oscillation of the plasma is called low-frequency oscillation, and the peak value of the low-frequency oscillation can often reach 100% of the average value of the discharge current. The large-amplitude low-frequency oscillation will impact the operation of the power supply system of the Hall thruster and affect its normal operation.

[0035] Specifically, in addition to the current with low-frequency oscillation frequency in the discharge current, there are also some high-frequency currents. Although they are very small, if these high-frequency currents pass through the excitation coil in the excitation unit, relatively large voltage fluctuations will be generated. Therefore, the excitation capacitor Cs is used to shunt this part of the high-frequency current to prevent the high-frequency current from passing through the excitation coil and protect the power supply system of the Hall thruster.

[0036] The number of turns of the excitation coil L2 is determined according to the magnetic field design requirements of the Hall thruster. Once the number of turns of the excitation coil L2 is determined, its equivalent inductance is determined. Generally, the inductance of the excitation coil L2 is on the order of mH.

[0037] In this embodiment, the current on the loop of the excitation unit 2 is the combined action of two parts. One part is the discharge current, which includes a DC component and an alternating component. The alternating component is mainly the oscillating part of the discharge current, and the frequency band ranges from dozens of kilohertz to dozens of megahertz. The other part is the excitation current provided by the excitation power supply Us, which is mainly DC. Therefore, the DC component includes the DC of the discharge current and the DC provided by the excitation power supply Us.

[0038] The DC component cannot pass through the excitation capacitor Cs and only forms a fixed magnetic field through the excitation coil L2. The alternating component in the discharge current will pass through the excitation coil L2 and the excitation capacitor Cs respectively and be shunted according to the inductive reactance of the excitation coil L2 and the capacitive reactance of the excitation capacitor Cs. The alternating component passing through the excitation coil L2 will form a changing magnetic field. When the low-frequency oscillation of the discharge current increases, that is, the alternating component increases, the magnetic field will also increase, restricting the growth of the discharge current. When the low-frequency oscillation of the discharge current decreases, the magnetic field will also decrease, maintaining the discharge current, forming a self-consistent magnetic field to control the discharge current and realizing fluctuation suppression.

[0039] In this embodiment, the inductance L of the excitation coil L2 is taken as 0.2 mH. Considering the low-frequency oscillation frequency of 20 kHz, the equivalent inductive reactance of the excitation coil L2 is:

[0040] X Ls = 2πfL = 25.13 Ω (1)

[0041] Among them, X Ls is the inductive reactance, f is the frequency of the alternating current, and L is the inductance of the excitation coil L2.

[0042] To achieve fluctuation suppression, make X Cs > 10X Ls , the excitation capacitor Cs is taken as Cs = 0.01 uF, then the equivalent capacitive reactance of the excitation capacitor Cs is:

[0043] X Cs = 1 / 2πfC = 795.77 Ω (2)

[0044] Among them, X Cs is the capacitive reactance, and C is the capacitance of the excitation capacitor Cs.

[0045] In this embodiment, the other working parameters are specifically that the voltage value of the excitation power supply Us is 20 V, the inductance value of the filter coil L1 is 0.05 mH, the capacitance value of the filter capacitor C is 10 uF, the voltage value of the discharge power supply U d is 310 V, and the reverse breakdown voltage value of the diode Ds should be more than twice the voltage value of the discharge power supply U d .

[0046] In this embodiment, the other working parameters can also be specifically that the capacitance value of the excitation capacitor Cs is 0.02 uF, the voltage value of the excitation power supply Us is 20 V, the inductance value of the filter coil L1 is 0.01 mH, the capacitance value of the filter capacitor C is 5 uF, the voltage value of the discharge power supply U d is 410 V, and the reverse breakdown voltage value of the diode Ds should be more than twice the voltage value of the discharge power supply U d .

[0047] In this embodiment, the other working parameters can also be specifically that the capacitance value of the excitation capacitor Cs is 0.01 uF, the voltage value of the excitation power supply Us is 15 V, the inductance value of the filter coil L1 is 0.02 mH, the capacitance value of the filter capacitor C is 10 uF, the voltage value of the discharge power supply Ud is 410 V, and the reverse breakdown voltage value of the diode Ds should be more than twice the voltage value of the discharge power supply U d .

[0048] Embodiment 2

[0049] As Figure 3 shown, a method for exciting power supply of a Hall thruster provided in this embodiment includes the following steps:

[0050] S101. After the cathode of the Hall thruster 3 is heated to a preset temperature, turn on the discharge power supply U d , and turn off the excitation power supply U d in the excitation unit 2, and the Hall thruster 3 starts to ignite.

[0051] Specifically, turn on the discharge power supply U d , keep the excitation power supply Us in the excitation unit 2 turned off, supply neutral gas to the anode of the Hall thruster 3, and the cathode of the Hall thruster 3 emits electrons into the channel to ionize the neutral gas. The discharge power supply U d forms a discharge loop through the filtering coil L1 of the filtering unit 1, the anode of the Hall thruster 3, and the cathode of the Hall thruster 3. The discharge current passes through the excitation coil L2 in the excitation unit 2, and a magnetic field in the Hall thruster channel is synchronously formed during the establishment of the discharge current. Before the electrons enter the channel to form a discharge, there is no magnetic field in the channel, and only an electric field formed by applying a voltage from the discharge power supply to the anode of the Hall thruster 3 exists. During the process of electrons moving towards the high potential of the anode of the Hall thruster 3, they are likely to obtain energy in the electric field to ionize neutral atoms, promoting ignition, and thus reducing the requirements for ignition start parameters. And the discharge power supply U d During the discharge startup process, the current in the discharge loop is gradually established, and the magnetic field of the Hall thruster 3 is also established accordingly, restricting the energy acquisition of electrons, making the ignition startup stable and not forming a large ignition impact peak.

[0052] S102. After the Hall thruster 3 ignites successfully, turn on the excitation power supply Us in the excitation unit 2. The excitation power supply Us provides an excitation voltage to adjust the magnetic field strength of the Hall thruster 3.

[0053] After the Hall thruster 3 ignites successfully, turn on the excitation power supply Us. The excitation power supply Us provides an excitation voltage, and by adjusting the current in the excitation coil L2, the magnetic field strength of the Hall thruster 3 is adjusted to maintain the steady-state operation during the discharge operation stage.

[0054] The beneficial effect of the present invention is that it makes full use of the original structure of the Hall thruster 3, connects the excitation unit 2 in series into the discharge loop. During the ignition startup stage, only turn on the discharge power supply and keep the excitation power supply Us turned off, which can reduce the requirements for ignition start parameters. At the same time, by adding the diode Ds and the excitation capacitor Cs, the stability during the discharge operation stage is improved, and the rated design power of the excitation power supply Us and the pressure of the discharge oscillation filter design are reduced.

[0055] The technical features of the above embodiments can be combined arbitrarily. For the sake of brief description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0056] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. An excitation power supply device for a Hall thruster, characterized in that, The device includes: a discharge power supply, a filtering unit, and an excitation unit; One end of the excitation unit and the first end of the filtering unit are both connected to the negative electrode of the discharge power supply. The negative electrode of the discharge power supply is grounded. The other end of the excitation unit is connected to the cathode of the Hall thruster. The excitation unit is used to provide an excitation voltage; The second end of the filtering unit is connected to the anode of the Hall thruster, and the third end of the filtering unit is connected to the positive electrode of the discharge power supply.

2. The exciting power supply device of the Hall thruster according to claim 1, characterized in that The excitation unit includes an excitation coil, an excitation capacitor, a diode, and an excitation power supply; One end after the excitation coil and the excitation capacitor are connected in parallel is respectively connected to the negative electrode of the diode and the cathode of the Hall thruster; the positive electrode of the diode is connected to the positive electrode of the excitation power supply; the other end after the excitation coil and the excitation capacitor are connected in parallel is connected to the cathode of the excitation power supply; the excitation power supply is used to provide an excitation voltage to pass an excitation current into the excitation coil to adjust the magnetic field strength of the Hall thruster.

3. The excitation power supply device of the Hall thruster according to claim 1, characterized in that, The filtering unit includes a filtering capacitor and a filtering coil; One end of the filtering capacitor and one end of the excitation unit are both connected to the negative electrode of the discharge power supply; The other end of the filtering capacitor is respectively connected to one end of the filtering coil and the anode of the Hall thruster; The other end of the filtering coil is connected to the positive electrode of the discharge power supply.

4. A method for exciting power supply of a Hall thruster, characterized in that, The method includes: After the cathode of the Hall thruster is heated to a preset temperature, the discharge power supply is turned on, and the excitation power supply in the excitation unit is turned off, and the Hall thruster starts ignition; After the Hall thruster ignites successfully, the excitation power supply in the excitation unit is turned on, and the excitation power supply provides an excitation voltage to adjust the magnetic field strength of the Hall thruster.

5. The exciting power supply method of the Hall thruster according to claim 4, characterized in that The step of turning on the discharge power supply and the Hall thruster starting ignition specifically includes: After the discharge power supply is turned on, a voltage is applied to the anode of the Hall thruster to make the Hall thruster ignite successfully.

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