Hall thruster hollow cathode ignition circuit and control method

Abstract

The invention provides a Hall thruster hollow cathode ignition circuit and a control method, Hall thruster hollow cathode ignition adopts two selectable cathode ignition modes of a cathode power supply and an anode power supply, the cathode power supply comprises a constant current source for cathode heating and a voltage source for cathode ignition, the anode power supply is mainly used for supplying power to an electric thruster anode, and the cathode power supply is mainly used for supplying power to an electric thruster cathode. Cathode ignition power supply can be achieved by connecting the change-over switch and the cathode power source in parallel. Through time sequence design, automatic switching of two cathode ignition modes can be achieved, and timing output of thrust of the Hall thruster is achieved. According to the ignition circuit and the control method, the reliability of cathode ignition of the Hall thruster is improved on the premise that a power module is not added.

Description

Technical Field

[0001] This invention relates to the field of space electric propulsion technology, specifically to a Hall thruster hollow cathode ignition circuit and control method. Background Technology

[0002] Hall thrusters used in space electric propulsion systems provide thrust to spacecraft. The electrons generated by their hollow cathodes are a prerequisite for the Hall thrusters to generate plasma. The electrons emitted by the cathodes enter the discharge chamber of the electric thruster and collide with the propellant, generating a large number of electrons and ions. Under the action of the electric field, they are accelerated, thereby achieving the purpose of generating thrust.

[0003] The hollow cathode mainly consists of an emitter, an emitter heater, and an ignition electrode. The ignition electrode power supply is applied between the ignition electrode and the emitter of the hollow cathode, and its function is to guide plasma movement and maintain the discharge of the emitter. Typically, the emitter heater is heated first, and a high ignition voltage is applied between the ignition electrode and the emitter to induce a gas discharge between the emitter and the ignition electrode.

[0004] Currently, cathode power supplies, both domestically and internationally, typically consist of a constant current power supply with a high open-circuit output voltage. The power supply operates at its maximum open-circuit voltage before the hollow cathode emitter emits electrons, and then operates at a constant current output after electron emission. The drawback of this approach is that the open-circuit output voltage is not adjustable. When the electric thruster reaches the end of its lifespan, the ignition impedance of the hollow cathode decreases, making it impossible to maintain high voltage across the ignition electrode. This prevents the gas between the ignition electrode and the emitter from breaking down, leading to ignition failure of the hollow cathode.

[0005] Patent application CN118548193A discloses a Hall effect electric propulsion ignition method and system, including: a cathode default parameter ignition cycle control process, determining whether cathode ignition is successful; if yes, then an anode control process; if no, then a cathode heating current modification ignition cycle control process, determining whether cathode ignition is successful; if yes, then an anode control process; if no, then a cathode heating current and ignition voltage modification cycle control process, determining whether cathode ignition is successful; if yes, then an anode control process; if no, then simultaneous cathode and anode ignition, and an anode control process. However, this patent cannot completely solve the existing technical problems, nor can it meet the needs of this invention. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a Hall thruster hollow cathode ignition circuit and control method.

[0007] The Hall thruster hollow cathode ignition circuit provided by the present invention includes a cathode power supply module and an anode power supply module; The cathode power supply module includes a cathode heating power supply and a cathode ignition power supply. The cathode heating power supply is a constant current source, and the cathode ignition power supply is a voltage source. The anode power supply module is a high-voltage regulated power source used to supply power to the anode of the electric thruster; The anode power module is connected in parallel with the cathode power module via a switching switch as a backup cathode ignition power supply and provides an adjustable cathode ignition voltage. The ignition circuit also includes multiple switches, including a thruster ignition electrode power supply switch S1, a thruster cathode current switching switch S2 and S3, and a thruster anode power supply switch S4; the switches are configured to switch between the cathode heating stage, the cathode ignition stage, the anode power supply ignition cathode stage, and the anode start-up stage under the control of the control unit.

[0008] Preferably, the cathode heating power supply outputs current to the thruster cathode heater by turning on switches S2 and S3 and turning off switch S1 at the start of ignition; after a predetermined cathode heating time, switch S1 is turned on to supply power to the thruster ignition electrode.

[0009] Preferably, after successful cathode ignition, the control unit is configured to select whether to disconnect switch S3 based on the modifiable flag bit, so that the constant current source of the cathode power module supplies power only to the cathode ignition electrode.

[0010] Preferably, when the cathode power module fails to ignite, the anode power module sets the anode power voltage reference UAB as the cathode ignition voltage and turns on switch S1 to supply power to the thrust ignition electrode.

[0011] The control method for the hollow cathode ignition circuit of the Hall thruster provided by the present invention includes the following steps: Step 1: At the start of the Hall thruster ignition process, set a countdown and start timing; connect the cathode power module, anode power module and valve control circuit, and open the upstream valve of the cathode to connect the cathode gas path; Step 2: Set the cathode power module current reference IAC, start the cathode power supply, heat the hollow cathode, and wait for the preset time; Step 3: Based on the number of available power supplies, modify the flag to select whether to enable the anode power supply to ignite the cathode. If enabled, proceed to Step 4; if not enabled, turn on the thruster anode power supply switch S4, set the anode power supply voltage reference UAC, turn on the thruster ignition electrode power supply switch S1, and wait for a preset time before determining whether the thruster cathode ignition current is greater than the judgment value. If it is greater than the judgment value, wait for a preset time and then, based on the number of available power supplies, modify the flag to select whether to disconnect the thruster cathode current switching switch S3, and proceed to Step 5; if it is less than the judgment value, turn off the thruster ignition electrode power supply switch S1, turn off the thruster anode power supply switch S4, and proceed to Step 4. Step 4: Set the anode power supply voltage reference UAB, start the anode power supply, and turn on the thruster ignition electrode power supply switch S1; after waiting for a preset time, select whether to disconnect the thruster cathode current switching switch S3 according to the number of available parameters; after waiting for a preset time, turn off the anode power supply, and then turn on the thruster anode power supply switch S4 to set the anode power supply voltage reference UAC. Step 5: Connect the anode gas path, wait for the countdown to end, start the anode power supply. If the anode current is greater than the judgment value, return to the program execution status word "thrust ignition successful"; if the anode current is less than the judgment value, execute the electric propulsion system shutdown procedure and return to the program execution status word "thrust ignition failed".

[0012] Preferably, in step 3, if the anode power supply is not used to ignite the cathode and the thruster cathode ignition current is greater than the judgment value, then after waiting for a preset time, the switch S3 is selected to be disconnected according to the number of available flags; wherein, when the switch S3 is closed, the cathode heater and the cathode ignition electrode automatically distribute the current reference IAC of the cathode power supply module according to their own resistance values; after the switch S3 is disconnected, the current reference IAC is fully supplied to the cathode ignition electrode.

[0013] Preferably, before disconnecting switch S3, the current reference IAC is modified so that the modified current reference IAC is fully supplied to the cathode ignition electrode.

[0014] Preferably, the determination value is a preset current threshold, which is used to determine whether the cathode has been successfully ignited or the anode has been successfully started.

[0015] Preferably, in steps 3 and 4, the operation of selecting whether to enable the anode power supply to ignite the cathode and whether to disconnect the thruster cathode current switching switch S3 according to the number of ignition points is performed by the control unit. The control unit judges the status of the flag bit according to the preset program and executes the control method steps of the Hall thruster hollow cathode ignition circuit accordingly.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) If the cathode fails to ignite using the cathode power supply, the system can automatically switch to the anode power supply ignition cathode mode, thereby improving the success rate of cathode ignition in the electric propulsion system. (2) In response to the impedance change of the hollow cathode at the end of the life of the Hall thruster, the anode power supply provides an adjustable ignition voltage to power the ignition electrode of the hollow cathode of the electric thruster. This ignition method improves the reliability of cathode ignition at the end of the life of the electric propulsion system without adding a power supply module. Attached Figure Description

[0017] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a circuit diagram of a specific embodiment of the hollow cathode ignition circuit for the Hall thruster of the present invention; Figure 2 This is a control flowchart of the hollow cathode ignition circuit and control method for the Hall thruster of the present invention. Detailed Implementation

[0018] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0019] Example like Figure 1 As shown, this invention provides a hollow cathode ignition circuit for a Hall thruster, including a cathode power supply module and an anode power supply module. The cathode power supply module includes a cathode heating power supply (constant current source) and a cathode ignition power supply (voltage source). The anode power supply is a high-voltage regulated power supply, whose main function is to supply power to the anode of the electric thruster. The anode power supply is connected in parallel with the cathode power supply through a switching switch, acting as a backup cathode ignition power supply and providing an adjustable cathode ignition voltage.

[0020] When ignition begins, switches S2 and S3 of the cathode power module are turned on, and the cathode heating power supply (constant current source) of the cathode power module is output. At this time, the thrust ignition electrode power supply S1 is turned off, and the low-voltage constant current terminal outputs current to the thrust cathode heater, and the thrust cathode begins to heat up. After the predetermined cathode heating time, the thrust ignition electrode power supply S1 is turned on. After successful cathode ignition, the constant current source of the cathode power module simultaneously supplies power to both the cathode heating electrode and the cathode ignition electrode.

[0021] Once the cathode ignition is successful, the thruster cathode current switching switch S2 can be disconnected. At this time, the constant current source of the cathode power module only supplies power to the cathode ignition electrode.

[0022] The Hall thruster hollow cathode ignition employs two selectable cathode ignition modes: cathode power supply and anode power supply. If cathode ignition fails using the cathode power supply, the system can automatically switch to the anode power supply mode. To address the impedance changes in the hollow cathode towards the end of the Hall thruster's lifespan, the anode power supply provides an adjustable ignition voltage to the ignition electrode of the hollow cathode. This ignition circuit improves the reliability of cathode ignition at the end of the electric propulsion system's lifespan without requiring an additional power supply module.

[0023] like Figure 2As shown, the present invention provides a control method for a hollow cathode ignition circuit of a Hall thruster, comprising the following steps: (1) Set a countdown at the start of the Hall thruster ignition process. T starts timing, cathode power module is turned on, anode power module is turned on, valve control circuit is turned on, cathode upstream valve is opened, cathode gas path is connected, and step (2) is entered. (2) Hollow cathode heating stage: Set the cathode power module current reference IAC (i.e., cathode heating current value), start the cathode power supply, wait for Tfire duration, and proceed to step (3). (3) Hollow cathode ignition stage: Select whether to enable anode power supply to ignite cathode according to the number of available numbers modified flag. If enabled, proceed to step (4). Specifically, determine whether the thruster cathode ignition current is greater than the judgment value. If it is less than the judgment value (cathode fails to ignite successfully), proceed to step (4) automatically. If not enabled, connect thruster anode power supply S4, set anode power supply voltage reference UAC (i.e., anode initial voltage), connect thruster ignition electrode power supply S1, and wait for Tjudge time to determine whether thruster cathode ignition current is greater than the judgment value. If it is greater than the judgment value, wait for Tchange time and select whether to disconnect thruster cathode current switching switch S3 according to the number of available numbers modified flag. Proceed to step (5). Specifically, when the switching switch is closed, the cathode heating wire and cathode ignition electrode automatically distribute the cathode power module current reference IAC (i.e., cathode heating current value, usually 4A) through their own resistance. After the switch is turned off, cathode heating is no longer performed, and the cathode power module current reference IAC is fully supplied to the cathode ignition electrode (the IAC will be modified before the switch is turned off, and the modified IAC (usually 1A) will be fully supplied to the cathode ignition electrode). Under certain conditions, the stability of cathode self-sustaining ignition can be guaranteed. If it is less than the judgment value, the thruster ignition electrode power supply S1 is turned off, the thruster anode power supply switch S4 is turned off, and the process proceeds to step (4). (4) Anode power supply ignition cathode stage: Set the anode power supply voltage reference UAB (i.e., cathode ignition voltage), start the anode power supply, and connect the thruster ignition electrode power supply S1. After waiting for the Tchange duration, modify the flag bit according to the number of available parameters to select whether to disconnect the thruster cathode current switching switch S3. After waiting for the Tclose duration, turn off the anode power supply. Then connect the thruster anode power supply S4, set the anode power supply voltage reference UAC (i.e., anode initial voltage), and proceed to step (5); (5) Hall thruster anode start-up stage: First, connect the anode gas path and wait for the countdown. When T ends, the anode power supply is started. If the anode current is greater than the judgment value, the program execution status word "thrust ignition successful" is returned. If the anode current is less than the judgment value, the electric propulsion system shutdown procedure is executed and the program execution status word "thrust ignition failed" is returned.

[0024] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0025] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A hollow cathode ignition circuit for a Hall thruster, characterized in that, Includes a cathode power module and an anode power module; The cathode power supply module includes a cathode heating power supply and a cathode ignition power supply. The cathode heating power supply is a constant current source, and the cathode ignition power supply is a voltage source. The anode power supply module is a high-voltage regulated power source used to supply power to the anode of the electric thruster; The anode power module is connected in parallel with the cathode power module via a switching switch as a backup cathode ignition power supply and provides an adjustable cathode ignition voltage. The ignition circuit also includes multiple switches, including a thruster ignition electrode power supply switch S1, a thruster cathode current switching switch S2 and S3, and a thruster anode power supply switch S4; the switches are configured to switch between the cathode heating stage, the cathode ignition stage, the anode power supply ignition cathode stage, and the anode start-up stage under the control of the control unit.

2. The Hall thruster hollow cathode ignition circuit according to claim 1, characterized in that, When ignition begins, the cathode heating power supply connects switches S2 and S3 and disconnects switch S1 to output current to the thruster cathode heater; after a predetermined cathode heating time, switch S1 is connected to supply power to the thruster ignition electrode.

3. The Hall thruster hollow cathode ignition circuit according to claim 2, characterized in that, After successful cathode ignition, the control unit is configured to select whether to disconnect switch S3 based on the number of ignition points modified, so that the constant current source of the cathode power module supplies power only to the cathode ignition electrode.

4. The Hall thruster hollow cathode ignition circuit according to claim 1, characterized in that, When the cathode power module fails to ignite, the anode power module sets the anode power voltage reference UAB as the cathode ignition voltage and turns on switch S1 to supply power to the thruster ignition electrode.

5. A control method based on the Hall thruster hollow cathode ignition circuit according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: At the start of the Hall thruster ignition process, set a countdown and start timing; connect the cathode power module, anode power module and valve control circuit, and open the upstream valve of the cathode to connect the cathode gas path; Step 2: Set the cathode power module current reference IAC, start the cathode power supply, heat the hollow cathode, and wait for the preset time; Step 3: Based on the number of available power supplies, modify the flag to select whether to enable the anode power supply to ignite the cathode. If enabled, proceed to Step 4; if not enabled, turn on the thruster anode power supply switch S4, set the anode power supply voltage reference UAC, turn on the thruster ignition electrode power supply switch S1, and wait for a preset time before determining whether the thruster cathode ignition current is greater than the judgment value. If it is greater than the judgment value, wait for a preset time and then, based on the number of available power supplies, modify the flag to select whether to disconnect the thruster cathode current switching switch S3, and proceed to Step 5; if it is less than the judgment value, turn off the thruster ignition electrode power supply switch S1, turn off the thruster anode power supply switch S4, and proceed to Step 4. Step 4: Set the anode power supply voltage reference UAB, start the anode power supply, and turn on the thruster ignition electrode power supply switch S1; After waiting for a preset time, modify the flag bit according to the number of available entries to select whether to disconnect the thruster cathode current switching switch S3; After waiting for a preset time, turn off the anode power supply, then turn on the thruster anode power supply switch S4 and set the anode power supply voltage reference UAC. Step 5: Connect the anode gas path, wait for the countdown to end, start the anode power supply. If the anode current is greater than the judgment value, return to the program execution status word "thrust ignition successful"; if the anode current is less than the judgment value, execute the electric propulsion system shutdown procedure and return to the program execution status word "thrust ignition failed".

6. The control method for the hollow cathode ignition circuit of the Hall thruster according to claim 5, characterized in that, In step 3, if the anode power supply is not used to ignite the cathode and the thruster cathode ignition current is greater than the judgment value, then after waiting for a preset time, the switch S3 is selected to be disconnected according to the number of available flags. When the switch S3 is closed, the cathode heater and the cathode ignition electrode automatically distribute the current reference IAC of the cathode power supply module according to their own resistance values. After the switch S3 is disconnected, the current reference IAC is fully supplied to the cathode ignition electrode.

7. The control method for the hollow cathode ignition circuit of the Hall thruster according to claim 6, characterized in that, Before disconnecting switch S3, the current reference IAC is modified, and the modified current reference IAC is supplied entirely to the cathode ignition electrode.

8. The control method for the hollow cathode ignition circuit of the Hall thruster according to claim 5, characterized in that, The judgment value is a preset current threshold, used to determine whether the cathode has been successfully ignited or the anode has been successfully started.

9. The control method for the hollow cathode ignition circuit of the Hall thruster according to claim 5, characterized in that, In steps 3 and 4, the operations of selecting whether to enable the anode power supply to ignite the cathode and whether to disconnect the thruster cathode current switching switch S3 based on the number of available flags are both performed by the control unit. The control unit determines the flag status according to the preset program and executes the control method steps of the Hall thruster hollow cathode ignition circuit accordingly.

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