Power supply device

Abstract

Provided is a power supply device for supplying power to an electric propulsion machine that generates propulsion force of a spacecraft, the power supply device comprising: a plurality of batteries; a plurality of first switch units that are provided corresponding to each of two adjacent batteries, the switch units switching the connection between the corresponding two batteries to a series connection or a parallel connection; and a second switch unit that switches whether a power supply source is connected to each of the batteries.

Description

power supply

[0001] This application claims priority to Japanese Patent Application No. 2024-007472, filed on Jan. 22, 2024, the contents of which are incorporated herein by reference.

[0002] The use of electric propulsion devices, which generate thrust to control the orbit and attitude of spacecraft such as satellites, is expanding, and the market is growing rapidly. Compared to chemical propulsion devices, electric propulsion devices require less propulsion gas on board spacecraft, and therefore are increasingly being adopted not only for deep space exploration satellites and geostationary satellites, but also for constellation satellites operating in low orbit. In recent years, the use of electric propulsion systems, particularly those using Hall thrusters, has been rapidly increasing. This is due to the advantage that Hall thruster systems generate high thrust per unit of power.

[0003] Hall thrusters generate thrust by ionizing a specific gas, such as xenon, to generate plasma, accelerating ions extracted from the plasma, and then propelling the ions into space. In a Hall thruster system, a power processing unit (PPU) supplies power to the Hall thruster to generate a discharge, which then extracts ions from the plasma generated by the discharge. In a Hall thruster system, the power required for the Hall thruster's operation is supplied to the power processing unit via a power controller from, for example, a solar panel (photovoltaic power generation device) or a battery. Therefore, the power available to the Hall thruster depends on the power generated by the spacecraft. On the other hand, it is generally more difficult to increase the propulsion efficiency of a Hall thruster as the power supplied to it decreases. For this reason, low-power Hall thrusters, ranging from several tens to several hundred watts, do not have very high thrust-to-power ratios, which represent the thrust generated per unit of power, or specific impulse, which corresponds to the amount of gas consumed. However, small spacecraft (e.g., 100 kg class) that do not generate much power have no choice but to choose low-power Hall thrusters, which do not have high propulsion efficiency. As a result, small spacecraft equipped with low-power Hall thrusters have little advantage over the Hall thrusters in terms of the reduction in propulsion gas and the high thrust generated per unit of power, and this has sometimes limited the missions in which they can demonstrate their superiority over spacecraft equipped with other propulsion systems.

[0004] To equip a small spacecraft with a Hall thruster of a power level capable of achieving the high thrust-to-power ratio and high propulsion efficiency inherent to Hall thrusters (hereinafter referred to as a "high-power Hall thruster"), it is conceivable to adopt an intermittent operation method, in which a power controller operates the Hall thruster by supplying power from a battery, such as a system power supply for operating the spacecraft's systems, to a power processor for a short period of time, and then waits for the battery to be charged before supplying power to the power processor. However, adopting an intermittent operation method requires that the battery and power controller have high power. In addition, the power processor is also configured to handle high power. Here, the power processor is composed of multiple power sources, such as an anode power supply, a keeper power supply, a heater power supply, and a coil power supply, and a power controller. This power processor accounts for a large proportion of the weight and cost of a Hall thruster system. Therefore, even if high propulsion efficiency can be achieved by installing a high-power Hall thruster in a small spacecraft, the overall advantages of the system may be reduced.

[0005] Conventionally, technologies related to miniaturization and cost reduction of power processing units have been proposed. One such proposal is to miniaturize the anode power supply, which accounts for a large portion of the power supplied to the Hall thruster among the multiple power sources constituting the power processing unit. Examples of miniaturization techniques for the anode power supply include a technique using a resonant converter as the anode power supply (e.g., Patent Document 1) and a technique for miniaturizing the filter included in the anode power supply by fluctuating the output voltage of the anode power supply at high frequency to suppress the discharge instability specific to Hall thrusters (e.g., Patent Document 2). Another proposal is to eliminate (delete) the heater power supply for the hollow cathode included in the Hall thruster among the multiple power sources constituting the power processing unit, and instead apply a high-voltage pulse generated by a keeper power supply to initiate a discharge in the hollow cathode (e.g., Patent Document 3). In this conventional technique, electrons are powerfully drawn from the hollow cathode by a high-voltage pulse generated by the keeper power supply, rather than heating the electron-emitting material with the heater power supply, generating a discharge and plasma between the hollow cathode and the keeper electrode.

[0006] US Patent No. 6,169,668 Specification Japanese Patent Application Laid-Open No. 2014-005762 Japanese Patent Application Laid-Open No. 2022-530748

[0007] However, in conventional technologies that reduce the size and cost of the power processing unit by miniaturizing the anode power supply, the anode power supply, which is a power source essential for accelerating and ejecting gas in a Hall thruster, is miniaturized, which may result in other issues for ensuring the performance of the Hall thruster system, such as the need to increase the power density of the anode power supply. On the other hand, in conventional technologies that reduce the size and cost of the power processing unit by eliminating the heater power supply, other issues for ensuring the continued operation of the Hall thruster system may arise, such as the need to prevent material wear on the keeper electrode (or the end of the hollow cathode facing the keeper electrode) due to arcing of the high-voltage pulse generated by the keeper power supply and the need to prevent deterioration of insulation between the electrodes due to material wear. For this reason, in conventional technologies, it may be difficult to demonstrate the advantages of installing a high-power Hall thruster on a small spacecraft, considering the mission to be performed by the spacecraft.

[0008] The present invention has been made based on the above-mentioned recognition of the problem, and has an object to provide a power supply device that can more efficiently supply power to an electric propulsion.

[0009] In order to achieve the above object, a power supply device according to one aspect of the present invention is a power supply device that supplies power to an electric propulsion that generates thrust for a spacecraft, and is equipped with a plurality of batteries, a first switch unit provided in a plurality of units corresponding to each two adjacent batteries, which switches the connection between the corresponding two batteries between a series connection and a parallel connection, and a second switch unit which switches whether to connect a power supply source to each of the batteries.

[0010] According to one aspect of the present invention, it is possible to provide a power supply device that can more efficiently supply power to an electric propulsion.

[0011] Fig. 1 is a diagram showing an example of the configuration of a Hall thruster system including a power processing unit having a power supply device according to an embodiment; Fig. 2 is a diagram showing an example of the configuration of a power supply device according to a first embodiment; Fig. 3 is a diagram showing an example of the operation of the power supply device according to the first embodiment; Fig. 4 is a diagram showing another example of use and configuration of the power supply device according to the first embodiment; Fig. 5 is a diagram showing an example of the configuration of a power supply device according to a second embodiment;

[0012] Hereinafter, an embodiment of the power supply device of the present invention will be described with reference to the drawings. When this application is translated from Japanese to English, as used throughout this disclosure, the singular forms "a," "an," and "the" may be deemed to include plural references unless the context clearly indicates otherwise. The power supply device of the present invention is applied to an electric propulsion system. The electric propulsion system may be a Hall thruster system including a Hall thruster, or an ion engine system including an ion engine. In the following description, a case will be described in which the electric propulsion system is a Hall thruster system including a Hall thruster.

[0013] A Hall thruster is an electric propulsion device that generates thrust to control the trajectory and attitude of a spacecraft as it moves through space by ionizing a specific gas (propulsion gas) such as xenon, generating plasma, accelerating the ions extracted from the plasma, and then ejecting the ions into space. The propulsion gas may be, for example, krypton, argon, nitrogen, oxygen, vaporized iodine, water, or other gases.

[0014] A spacecraft employing a Hall thruster system may be an artificial satellite that moves along a predetermined orbit above the surface of the Earth or another celestial body or object, or it may be an observation satellite that travels to observe other celestial bodies or objects (and may return to Earth). Other celestial bodies include planets other than Earth, such as Mars and Venus, moons such as the Moon and Titan, and asteroids such as Itokawa and Ryugu. Other objects include rocks.

[0015] [Configuration of Hall Thruster System] FIG. 1 is a diagram showing an example of the configuration of a Hall thruster system including a power processing unit with a power supply device according to an embodiment. The Hall thruster system 1 includes, for example, a Hall thruster 10 and a power processing unit (PPU) 20. FIG. 1A shows an example of the Hall thruster 10 as viewed from the side where ions extracted from a propulsion gas by plasma are ejected into space. FIG. 1B shows an example of a cross-sectional view of the Hall thruster 10 shown in FIG. 1A along the A-A' cross section, and an example of the connection between the Hall thruster 10 and the power processing unit 20. FIG. 1C shows an example of the configuration of the Hall thruster system 1.

[0016] First, the structure of the Hall thruster 10 will be described using FIGS. 1A and 1B. The Hall thruster 10 has a hollow cathode 15 disposed in the center of a cylindrical housing. From the center toward the periphery, an internal electromagnet 14a, a channel 11, and an external electromagnet 14b are arranged in a ring shape in this order. In the following description, when there is no need to distinguish between the internal electromagnet 14a and the external electromagnet 14b, they will simply be referred to as the "electromagnet 14." In the Hall thruster 10, the channel 11 is formed as a groove that runs along the electromagnet 14, and the groove is surrounded by a wall 13 made of, for example, ceramic. An anode 12 is disposed at the bottom of the groove that forms the channel 11.

[0017] Next, the configuration of the Hall thruster 10 and the power processing unit 20 and the connection between the Hall thruster 10 and the power processing unit 20 will be described using FIGS. 1B and 1C. FIG. 1C also shows spacecraft components related to the Hall thruster system 1. More specifically, it shows a power controller 100 that supplies power to each component (not shown) of the spacecraft, including the power processing unit 20, and a solar cell 120 and a battery 140 that output or store the original power supplied by the power controller 100 to each component (not shown). The power controller 100 controls the supply of power to each component of the spacecraft. For example, the power controller 100 converts the power to the voltage and current values ​​required by each component and supplies the power to each component. The solar cell 120 is, for example, a system power source that outputs power generated by a solar cell paddle (photovoltaic power generation device) equipped on the spacecraft. The battery 140 is a storage battery of a system power supply that stores the power supplied by the power controller 100 and supplies the stored power to the power controller 100 in accordance with control from the power controller 100. The power controller 100 may supply the power output by the solar cell 120 to each component included in the spacecraft, or may store the power output by the solar cell 120 in the battery 140 and receive power from the battery 140 as needed to supply power to each component included in the spacecraft. In the following description, when there is no need to distinguish between the solar cell 120 and the battery 140, they are referred to as the "system power supply."

[0018] The power controller 100 (which may include the solar cell 120 and the battery 140) is an example of a "power supply source." The solar cell 120 and the battery 140 are an example of a "system power source."

[0019] As described above, the Hall thruster 10 includes, for example, the channel portion 11, the anode 12, the wall portion 13, the electromagnet 14, and the hollow cathode portion 15. The hollow cathode portion 15 includes, for example, a hollow cathode body 15a, a keeper electrode body 15b, a heater 15c, and a gas supply pipe 15d. The power processing unit 20 supplies power based on the power supplied by the power controller 100 to each of the components included in the Hall thruster 10. The power processing unit 20 includes, for example, an anode power supply 30, a keeper power supply 40, a heater power supply 50, and a coil power supply 60. The anode power supply 30, the keeper power supply 40, the heater power supply 50, and the coil power supply 60 are each a DC power supply that supplies the power required by the corresponding component of the Hall thruster 10. Each of the anode power supply 30, the keeper power supply 40, the heater power supply 50, and the coil power supply 60 converts the power supplied by the power controller 100 and supplies it to the corresponding component.

[0020] The anode power supply 30 is a DC power supply that supplies power to the anode 12. The anode power supply 30 supplies power to the anode 12, for example, with a maximum voltage of 300 V and a current of 3 A. In this case, a 1 kW-class Hall thruster 10 is configured. The anode power supply 30 may also supply power to the anode 12 with a maximum voltage of 300 V and a current of 20 A. In this case, a 6 kW-class Hall thruster 10 is configured. The power supplied by the anode power supply 30 is not limited to a maximum voltage of 300 V. The anode power supply 30 may supply power with a maximum voltage of, for example, 150 V or 1000 V depending on the performance of the Hall thruster 10. The anode power supply 30 includes a plurality of batteries B and a battery drive unit BD. 1(c) shows an example of a configuration in which the anode power supply 30 includes n batteries B, battery B-1 to battery B-n (n is a natural number). The anode power supply 30 stores the power supplied by the power controller 100 in each battery B and supplies the stored power to the anode 12. A more detailed configuration of the anode power supply 30 will be described later.

[0021] The anode power supply 30 is an example of a "power supply device." The battery B is an example of a "battery."

[0022] The keeper power supply 40 is a DC power supply that supplies power to the keeper electrode body 15b. The keeper power supply 40 supplies power to the keeper electrode body 15b, for example, at a voltage of 200 V and a current of 1 A. While FIG. 1C shows a configuration in which the negative electrode side of the keeper power supply 40 is connected to the negative electrode side of the anode power supply 30 (connected to the cathode electrode Ec connected to the hollow cathode body 15a), the negative electrode side of the keeper power supply 40 may be connected to, for example, a dedicated electrode provided in the Hall thruster 10. The keeper power supply 40 may be omitted, for example, in a configuration in which power is supplied from the anode power supply 30 to the keeper electrode body 15b.

[0023] The heater power supply 50 is a DC power supply that supplies power to the heater 15c. The heater power supply 50 supplies, for example, power with a voltage of 100 V and a current of 1 A, power with a voltage of 10 V and a current of 10 A, or power with a voltage of 20 V and a current of 5 A to the heater 15c. While FIG. 1C illustrates a configuration in which the negative electrode of the heater power supply 50 is connected to the negative electrode of the anode power supply 30 (connected to the cathode electrode Ec connected to the hollow cathode body 15a), the negative electrode of the heater power supply 50 may be connected to, for example, a dedicated electrode provided in the Hall thruster 10. The heater power supply 50 may be omitted, for example, when a high-voltage pulse is applied to the keeper electrode body 15b by the keeper power supply 40.

[0024] The coil power supply 60 is a DC power supply that supplies power to the electromagnets 14 (more specifically, to the coils that constitute the internal electromagnet 14 a and the external electromagnet 14 b). The coil power supply 60 supplies, for example, power with a voltage of 100 V and a current of 1 A, power with a voltage of 10 V and a current of 10 A, or power with a voltage of 20 V and a current of 5 A to each of the electromagnets 14.

[0025] The keeper power supply 40, the heater power supply 50, and the coil power supply 60 may be, for example, a DC power supply with a fixed voltage and a fixed current, whose power output is turned on and off in accordance with control from the power controller 100 (which may be a power control unit, not shown, provided in the power processing unit 20).The keeper power supply 40, the heater power supply 50, and the coil power supply 60 may be a switching power supply, whose supplied voltage and current values ​​are controlled in accordance with control from the power controller 100 (which may be a power control unit, not shown, provided in the power processing unit 20).

[0026] The hollow cathode body 15a ionizes the propellant gas supplied into the channel portion 11 to extract ions, thereby supplying electrons for initiating operation of the Hall thruster 10, and also serves as an electron source for emitting electrons for maintaining plasma and electrically neutralizing accelerated ions during operation of the Hall thruster 10. The same propellant gas as that supplied to the anode 12 is supplied to the hollow cathode body 15a through a gas supply pipe 15d. The hollow cathode body 15a ionizes the propellant gas supplied through the gas supply pipe 15d and emits the generated electrons toward the channel portion 11. The negative side of an anode power supply 30 is connected to a cathode electrode Ec connected to the hollow cathode body 15a. 1B shows an example in which the cathode electrode Ec is disposed on the side of the housing of the Hall thruster 10 opposite the side where ions extracted from the plasma are ejected into space. However, the hollow cathode body 15a itself (which may be part of the gas supply pipe 15d) may serve as the cathode electrode Ec. A keeper electrode body 15b is disposed adjacent to the tip of the hollow cathode body 15a. However, the hollow cathode body 15a and the keeper electrode body 15b are insulated from each other. Furthermore, the outer periphery of the hollow cathode body 15a is covered with a heater 15c. The heater electrode Eh connected to the heater 15c is connected to the positive side of a heater power supply 50. In other words, the heater power supply 50 is connected between the heater 15c (heater electrode Eh) and the hollow cathode body 15a (cathode electrode Ec). The heater 15c generates heat in response to the power supplied by the heater power supply 50, thereby heating components called an emitter and electron-emitting material (not shown) provided in the hollow cathode body 15a, thereby causing more electrons to be emitted from the hollow cathode body 15a. The positive electrode of the keeper power supply 40 is connected to the keeper electrode Ek connected to the keeper electrode body 15b. In other words, the keeper power supply 40 is connected between the keeper electrode body 15b (keeper electrode Ek) and the hollow cathode body 15a (cathode electrode Ec).When a high voltage is applied to the keeper electrode body 15b by power supplied from the keeper power supply 40, a discharge occurs between the hollow cathode body 15a and the keeper electrode body 15b, and this discharge ionizes the propellant gas supplied into the hollow cathode body 15a from the gas supply pipe 15d, generating plasma. Electrons drawn from the plasma by the potential gradient between the hollow cathode body 15a and the keeper electrode body 15b are emitted toward the channel portion 11.

[0027] The anode 12 is a positive electrode that ionizes the propellant gas supplied into the channel portion 11 through the gas supply pipe 12a to extract ions. The supply of the propellant gas into the channel portion 11 through the gas supply pipe 12a and the amount of the propellant gas supplied are controlled, for example, by controlling the opening and closing of a valve disposed in the gas supply pipe 12a. A valve power supply (not shown) may be provided in the power processing unit 20. In this case, the power controller 100 may control the opening and closing of the valve disposed in the gas supply pipe 12a by controlling the voltage and current supplied to the valve from the valve power supply (not shown). The positive side of an anode power supply 30 is connected to the anode electrode Ea of the anode 12. That is, the anode power supply 30 is connected between the anode 12 (anode electrode Ea) and the hollow cathode body 15a (cathode electrode Ec). FIG. 1B shows an example in which the anode electrode Ea is disposed at the end of the housing of the Hall thruster 10, similar to the cathode electrode Ec, but the anode 12 itself may serve as the anode electrode Ea.

[0028] The anode 12 is an example of a "first power supply destination."

[0029] The electromagnet 14 has an anode 12 disposed therein and generates a magnetic field in an area surrounded by the wall portion 13. The electromagnet 14 has a configuration in which a coil is wound around a core material made of a magnetic material. The positive side of a coil power supply 60 is connected to a coil positive electrode Em+ connected to the positive terminal of the coil. The negative side of the coil power supply 60 is connected to a coil negative electrode Em- connected to the negative terminal of the coil. The electromagnet 14 generates a magnetic field in the channel portion 11 in response to the power supplied to the coil by the coil power supply 60. Although detailed connections between the coil power supply 60 and the coils are omitted in FIG. 1, power from the coil power supply 60 is supplied to both the coil of the internal electromagnet 14a and the coil of the external electromagnet 14b. For example, power from the coil power supply 60 is supplied to each of the coils of the internal electromagnet 14a and the external electromagnet 14b via a path that runs from the positive side of the coil power supply 60 through the coil positive electrode Em+, the positive terminal of the coil of the external electromagnet 14b, the negative terminal of the coil of the external electromagnet 14b, the positive terminal of the coil of the internal electromagnet 14a, the negative terminal of the coil of the internal electromagnet 14a, and the coil negative electrode Em-, and returns to the negative side of the coil power supply 60. The coil positive electrode Em+ and the coil negative electrode Em- are not limited to being configured to correspond to the coil of the internal electromagnet 14a and the coil of the external electromagnet 14b, respectively. For example, the electromagnet 14 may be configured to include a coil positive electrode Em+ and a coil negative electrode Em- corresponding to the coil of the internal electromagnet 14a, and a coil positive electrode Em+ and a coil negative electrode Em- corresponding to the coil of the external electromagnet 14b. In other words, the coil of the internal electromagnet 14a and the coil of the external electromagnet 14b may each be provided with a separate coil positive electrode Em+ and a separate coil negative electrode Em-. Furthermore, the configuration for supplying power to each of the coils of the internal electromagnet 14a and the external electromagnet 14b is not limited to the coil power supply 60. For example, the power processing unit 20 may not be provided with a coil power supply 60 (and therefore may not be provided with a coil positive electrode Em+ and a coil negative electrode Em-). In this case, for example, the coil of the internal electromagnet 14a and the coil of the external electromagnet 14b may each be connected between the hollow cathode body 15a and the cathode electrode Ec.More specifically, the hollow cathode body 15a may be connected to the cathode electrode Ec via the positive terminal of the coil of the external electromagnet 14b, the negative terminal of the coil of the external electromagnet 14b, the positive terminal of the coil of the internal electromagnet 14a, and the negative terminal of the coil of the internal electromagnet 14a, thereby supplying power to each of the coils of the internal electromagnet 14a and the external electromagnet 14b. In this case, the electromagnet 14 generates a magnetic field in the channel portion 11 according to the power supplied to the coil by passing a current through the coil that flows when the hollow cathode body 15a extracts ions from the propulsion gas supplied to the plasma in the channel portion 11.

[0030] In the Hall thruster 10, the anode 12 and hollow cathode body 15a are insulated from each other. In the Hall thruster 10, a magnetic field is generated in the channel portion 11 by the electromagnet 14, and a high voltage is applied to the anode 12 by power supplied by the anode power supply 30. This occurs in this order, in reverse order, or simultaneously. When electrons are extracted from the propulsion gas ionized by the plasma generated by discharge between the hollow cathode body 15a and the keeper electrode body 15b and released toward the channel portion 11, a discharge occurs between the anode 12 and the hollow cathode body 15a. This discharge ionizes the propulsion gas supplied into the channel portion 11 from the gas supply pipe 12a, generating plasma. In the Hall thruster 10, ions are accelerated and extracted from the plasma by the potential gradient generated within the plasma and ejected from the channel portion 11 into space.

[0031] First Embodiment [Configuration of Anode Power Supply] Next, the configuration of the anode power supply 30 will be described. FIG. 2 is a diagram showing an example of the configuration of a power supply device (anode power supply 30) according to the first embodiment. FIG. 2 also shows the anode 12 to which the anode power supply 30 supplies power, and the power controller 100 from which the anode power supply 30 receives power. The anode power supply 30 includes, for example, six batteries B (batteries B-1 to B-6), five switches 31 (switches 31-1 to 31-5), a switch 32, a switch 33, a resistor 34, a switch 35, six diodes 36 (diodes 36-1 to 36-6), and a diode 37.

[0032] Each of the batteries B- 1 to B- 6 is a storage battery that stores the power supplied by the power controller 100 .

[0033] Each of the switches 31-1 to 31-5 corresponds to two adjacent batteries B and is a switch for exclusively switching the connection between the corresponding two batteries B. Each of the switches 31-1 to 31-5 is, for example, a mechanical contact switch. Each of the switches 31-1 to 31-5 switches the connection between the corresponding two batteries B between either a series connection or a parallel connection. For example, the switch 31-1 corresponds to batteries B-1 and B-2 and connects the positive terminal of battery B-1 to the negative terminal of battery B-2, thereby connecting batteries B-1 and B-2 in series, and connects the negative terminals of batteries B-1 and B-2 together, thereby connecting batteries B-1 and B-2 in parallel. For example, the switch 31-2 corresponds to batteries B-2 and B-3 and, like the switch 31-1, connects batteries B-2 and B-3 in series or in parallel. The same is true for each of the switches 31-3 to 31-5. The switching of the connection of the corresponding battery B in each of the switches 31-1 to 31-5 is controlled, for example, by a battery drive unit BD. The battery drive unit BD controls each switch 31 so that the batteries B are connected in parallel when storing (charging) the power supplied by the power controller 100 in each battery B, and controls each switch 31 so that the batteries B are connected in series when outputting the power stored in the battery B to operate the Hall thruster 10.

[0034] Each of the switches 31-1 to 31-5 is an example of a "first switch section."

[0035] The switch 32 is a switch for exclusively switching components connected to both ends of the battery B. More specifically, the switch 32 switches between connecting the power controller 100 to both ends of each of the parallel-connected batteries B-1 to B-6, or connecting the anode 12 between the positive terminal of the final-stage battery B-6 in the series connection and the negative terminal of the first-stage battery B-1 in the series connection. The switch 32 is, for example, a mechanical contact switch. The switching of the connection destination of the switch 32 is controlled, for example, by a battery drive unit BD simultaneously with each of the switches 31-1 to 31-5. That is, the battery drive unit BD controls the switch 32 so that the power controller 100 is connected to both ends of each parallel-connected battery B when charging each battery B with power supplied by the power controller 100, and controls the switch 32 so that the anode 12 is connected to both ends of the series-connected batteries B-1 to B-6 when outputting power stored in the battery B to operate the Hall thruster 10.

[0036] The switch 32 also functions to isolate the power controller 100 from the operating Hall thruster 10. This is because, in Hall thrusters including the Hall thruster 10, noise is generally generated when a discharge occurs between the anode 12 and the hollow cathode body 15a. When the batteries B are connected in series to operate the Hall thruster 10 and stored power is supplied to the anode 12, the switch 32 is controlled by the battery drive unit BD simultaneously with each of the switches 31-1 to 31-5 to disconnect each battery B from the power controller 100. This prevents noise generated by a discharge between the anode 12 and the hollow cathode body 15a from leaking into the power controller 100 and affecting the anode power supply 30. In the anode power supply provided in a conventional Hall thruster system, the power controller and the operating Hall thruster can also be isolated from each other by, for example, converting DC power supplied by the power controller to AC power using a switching circuit or the like, converting the voltage (boosting) using a transformer or the like, and then rectifying the converted DC power by a rectifier circuit or the like before supplying it to the anode. In contrast, in the anode power supply 30, as described above, the power controller 100 can be isolated from each battery B and the power controller 100, in other words, isolated from the anode 12, simply by switching the switch 32. This makes it possible to isolate the power controller 100 from the operating Hall thruster 10 with a simpler configuration than conventional anode power supplies. In other words, the anode power supply 30 can obtain the power to be supplied to the anode 12 as DC power without converting the DC power supplied by the power controller 100 to AC power.

[0037] The switch 32 is an example of a "second switch unit." The positive terminal of the battery B-6 in the final stage of the series connection is an example of a "first positive terminal," and the negative terminal of the battery B-1 in the first stage of the series connection is an example of a "first negative terminal."

[0038] The switch 33 is disposed between the positive terminal of each battery B and the power controller 100 and controls the charging of the power supplied by the power controller 100 to each battery B. The switch 33 is a semiconductor switch configured with a semiconductor switching element such as an N-channel metal oxide semiconductor field effect transistor (MOSFET). FIG. 2 also shows a parasitic diode (so-called body diode) that is typically included in a metal oxide semiconductor field effect transistor. The gate terminal of the semiconductor switching element configuring the switch 33 is controlled (a control voltage or a control current is applied) by the battery drive unit BD. That is, the switch 33 is controlled to either an on or off state by the battery drive unit BD. The battery drive unit BD controls the switch 33 to the on state when charging each battery B with power supplied by the power controller 100, and controls the switch 33 to the off state when the voltage value corresponding to the power stored in each battery B becomes the voltage value corresponding to the power supplied (output) by the power controller 100, that is, when charging of each battery B is completed. The switch 33 controlled to the on state also functions to limit the current flowing from the power controller 100 to each battery B side.

[0039] The switch 33 is an example of a "fourth switch unit."

[0040] The resistor 34 is a resistive element for limiting the current flowing from the power controller 100 to each battery B when the power supplied by the power controller 100 is charged to each battery B. The smaller the difference between the voltage value corresponding to the power output by the power controller 100 and the voltage value corresponding to the power stored in each battery B, that is, the closer the state of charge of each battery B is to a fully charged state, the more the resistor 34 limits the current flowing from the power controller 100 to each battery B (reduces the current value). This enables the anode power supply 30 to improve safety when the power controller 100 charges each battery B. The resistor 34 may be omitted from the anode power supply 30.

[0041] The combination of the resistor 34 and the switch 33 is also an example of a "fourth switch section."

[0042] The switch 35 is disposed between the positive terminal of the battery B-6 in the final stage of the series connection and the anode electrode Ea of the anode 12. It controls the voltage value corresponding to the power supplied to the anode 12 from the series-connected batteries B-1 to B-6 so that it does not suddenly reach its maximum value when the Hall thruster 10 is operating. Here, the maximum voltage value corresponding to the power supplied to the anode 12 is the voltage value between the negative terminal of the battery B-1 in the lowest stage (first stage) of the series connection and the positive terminal of the battery B-6 in the highest stage (final stage). Like the switch 33, the switch 35 is also a semiconductor switch formed by a semiconductor switching element. Figure 2 also shows the body diode typically found in metal-oxide-semiconductor field-effect transistors (MOTs). The gate terminal of the semiconductor switching element constituting the switch 35 is also controlled (a control voltage or control current is applied) by the battery drive unit BD. However, the battery driving unit BD controls the gate terminal of the semiconductor switching element so that the time it takes for the voltage applied to the anode 12 from the series-connected battery B to change from 0 V to its maximum value—the so-called voltage rise time—is a predetermined time. More specifically, when the battery driving unit BD starts supplying power to the anode 12 from the series-connected battery B, it repeatedly controls the switch 35 to its on state and off state at predetermined time intervals, controlling the gate terminal of the semiconductor switching element so that the switch 35 remains on after the predetermined time has elapsed at which the voltage reaches its maximum value. At this time, the battery driving unit BD gradually lengthens the time for which the switch 35 is controlled to its on state (shortens the time for which it is controlled to its off state) at each predetermined time interval. In other words, the battery driving unit BD controls the rise time of the voltage applied to the anode 12 by controlling the switch 35 in a manner similar to a so-called soft turn-on function. This allows the voltage from the series-connected battery B to be applied to the anode 12 without causing a large current (inrush current) to flow, which would occur if the voltage were suddenly increased to its maximum value.

[0043] The switch 35 is an example of a "third switch unit."

[0044] Each of the diodes 36-1 to 36-6 is a rectifying element that allows or blocks current flow between the corresponding battery B-1 to B-6 and the power controller 100. In particular, each of the diodes 36-1 to 36-6 blocks the current of the power charged in the corresponding battery B-1 to B-6 from flowing toward the power controller 100. This improves safety when the anode power supply 30 supplies power to the anode 12 from the series-connected batteries B-1 to B-6. In the anode power supply 30, instead of each of the diodes 36-1 to 36-6, a mechanical contact switch or a semiconductor switch may be used as a configuration that blocks the current of the power charged in the corresponding battery B-1 to B-6 from flowing toward the power controller 100. In this case, the battery drive unit BD may control whether to allow or block current flow between the batteries B-1 to B-6 and the power controller 100. In the anode power supply 30, each of the diodes 36-1 to 36-6 may be omitted.

[0045] The diode 37 is a rectifying element that allows or blocks current flow between the batteries B-1 to B-6 and the power controller 100. In particular, the diode 37 blocks the current of the power charged in the batteries B-1 to B-6 from flowing toward the power controller 100. This improves safety in the anode power supply 30 when power is supplied to the anode 12 from the series-connected batteries B-1 to B-6. The diode 37 may be omitted from the anode power supply 30.

[0046] In the configuration of anode power supply 30 shown in FIG. 2, for example, when power is supplied to anode 12 from series-connected batteries B-1 to B-6, it is also possible to further increase or decrease the voltage value applied to anode 12. In this case, a voltage conversion circuit for increasing or decreasing the voltage, such as a DC-DC converter, may be disposed between the positive terminal of the final-stage battery B-6 in the series connection and switch 35 (i.e., before switch 35), or between switch 35 and anode electrode Ea of anode 12 (i.e., after switch 35). The configuration and operation of anode power supply 30 in this case can be easily understood from the configuration and operation of anode power supply 30 described above, and therefore a detailed description thereof will be omitted.

[0047] The voltage conversion circuit is an example of a "voltage conversion unit."

[0048] [Control and Operation of Anode Power Supply] Next, the control of the anode power supply 30 in the battery drive unit BD and the operation of the anode power supply 30 will be described. In the following description, an example will be described in which a small spacecraft is equipped with a Hall thruster 10 (hereinafter also referred to as a "high-power Hall thruster 10") with a power level of, for example, 1 kW, which can achieve the high thrust-to-power ratio and high propulsion efficiency inherent in Hall thrusters. More specifically, an example will be described in which the power controller 100 supplies power with a voltage of 50 V and a current of 1 A to the anode power supply 30 included in the power processing unit 20, and the anode power supply 30 supplies power with a maximum voltage of 300 V and a current of 3 A to the anode 12. Here, the charge capacity of each battery B corresponds to the power of a voltage of 50 V and a current of 1 A supplied by the power controller 100 to the anode power supply 30.

[0049] 3A and 3B are diagrams showing an example of the operation of the power supply device (anode power supply 30) according to the first embodiment. Fig. 3A shows the operation of the anode power supply 30 when storing (charging) power supplied by the power controller 100 in the battery B, and Fig. 3B shows the operation of the anode power supply 30 when outputting the power stored (charged) in the battery B to operate the Hall thruster 10.

[0050] When the power supplied by the power controller 100 is stored (charged) in the battery B, the battery drive unit BD connects the batteries B in parallel and controls the switches 31 and 32 so that the power supplied by the power controller 100 is supplied to each battery B. As a result, in the anode power supply 30, as shown in FIG. 3A, the negative terminals of the batteries B are connected to each other, and the switches 31-1 to 31-5 and the switch 32 are switched so that the power controller 100 is connected. At this time, the anode 12 of the Hall thruster 10 is disconnected from the anode power supply 30. The battery drive unit BD then controls the switch 33 to the on state. FIG. 3A shows a state in which power with a voltage value of 50 V and a current value of 1 A is supplied from the power controller 100 to the anode power supply 30. As a result, a total current of 1 [A] flows from the power controller 100 to the positive terminal of each battery B via the diode 37, resistor 34, switch 33, and corresponding diode 36, and each battery B is charged with the power supplied by the power controller 100. More specifically, since the configuration of the anode power supply 30 shown in FIG. 2 includes six batteries B, batteries B-1 to B-6, a current of 1 / 6 [A] flows through each battery B, and the battery B is charged with the power supplied by the power controller 100. Thereafter, the battery drive unit BD controls the switch 33 to the off state when the voltage value corresponding to the power stored in each battery B becomes the voltage value output by the power controller 100 = 50 [V]. This completes the charging of each battery B with the power supplied by the power controller 100.

[0051] When the power stored (charged) in the battery B is output to operate the Hall thruster 10, the battery drive unit BD connects the batteries B in series and controls the switches 31 and 32 so that the power is supplied to the anode 12 as if each battery B were a single battery (hereinafter referred to as the "series battery BS"). As a result, in the anode power supply 30, as shown in FIG. 3B, the positive and negative terminals of adjacent batteries B are connected, and the anode 12 is connected to both ends of the series battery BS. More specifically, the switch 32 is switched so that the positive terminal of the last battery B-6 of the series battery BS is connected to the anode electrode Ea of the anode 12, and the negative terminal of the first battery B-1 of the series battery BS is connected to the cathode electrode Ec of the Hall thruster 10. At this time, the power controller 100 is disconnected from the anode power supply 30. The battery drive unit BD controls the switch 35 in the same manner as the soft turn-on function. As a result, a voltage is applied to the anode 12 from the series battery BS, which changes from a voltage of 0 V to a maximum voltage of 300 V over a predetermined ramp-up time and remains at the maximum voltage after the predetermined ramp-up time has elapsed. (b) of FIG. 3 shows a state in which power with a voltage of 300 V and a current of 3 A is supplied from the series battery BS to the anode 12 via the switch 35. (b) of FIG. 3 shows a current of 3 A flowing from the series battery BS to the anode 12, but the actual current value flowing to the anode 12 is a current value corresponding to the load characteristics of the plasma in the channel unit 11. As a result, the Hall thruster 10 ionizes the propulsion gas using the plasma and ejects the extracted ions into space, generating thrust for the spacecraft.

[0052] With this configuration and operation (control of the battery drive unit BD), the anode power supply 30 connects each battery B in parallel to charge the power (power of the system power supply) supplied by the power controller 100, and connects each battery B in series (treating them as series batteries BS) to supply power to the anode 12. This allows the anode power supply 30 to more efficiently supply power to the anode 12, allowing a small spacecraft that cannot supply much power from the system power supply to be equipped with a high-power Hall thruster 10 that has a high thrust-to-power ratio, which represents the thrust generated per unit of power, and a high specific impulse, which corresponds to fuel consumption, i.e., how much propulsion gas is used. This enhances the advantages of a small spacecraft equipped with a Hall thruster system 1 that includes a power processing unit 20 incorporating the anode power supply 30. More specifically, since the high-power Hall thruster 10 has a higher thrust-to-power ratio and specific impulse than a low-power Hall thruster, when a spacecraft is moved using both a high-power Hall thruster 10 and a low-power Hall thruster in the same manner, the amount of propellant gas used, which accounts for a relatively large proportion of the spacecraft's weight, can be reduced. In other words, when the amount of velocity change required to move the spacecraft is the same, the amount of propellant gas carried can be reduced. On the other hand, when the amount of propellant gas carried is the same, the amount of velocity change of the spacecraft can be increased. This leads to an expansion of the range of missions that spacecraft can perform.

[0053] For example, if a small spacecraft were to be equipped with a high-power Hall thruster of 1 kW or so based on conventional thinking, it would be necessary to increase the power of the battery equivalent to battery 140 and the power controller. However, the anode power supply 30 allows the high-power Hall thruster 10 to be realized without increasing the power of the battery 140 and the power controller 100. In other words, by configuring the anode power supply 30 of the power processing unit 20 to include battery B, the battery 140 and the power controller 100 remain equivalent to conventional configurations that are not increased in power. Therefore, even if the power processing unit 20 is somewhat larger than the conventional power processing unit, the overall configuration of the high-power Hall thruster 10 of, for example, 1 kW or so can be made smaller, allowing it to be installed in a small spacecraft. Furthermore, when comparing the power processing unit 20 with a conventional power processing unit with a large capacity, the shorter the ion injection time per cycle in the high-power Hall thruster 10, the smaller the charge capacity of battery B can be, giving the power processing unit 20 an advantage. Furthermore, the switching power supplies that make up the respective power supplies provided in conventional large-capacity power processing units cause noise due to their switching operations even at times unrelated to discharge or the plasma generated by this discharge, so the anode power supply 30 configured with battery B is also superior from the standpoint of noise.

[0054] 2 shows an example of a configuration in which switches 31 and 32 are mechanical contact type switches and switches 33 and 35 are semiconductor switches. However, the configurations of switches 31, 32, 33, and 35 are not limited to the configuration shown in Fig. 2 as long as they are capable of realizing the respective functions described above. For example, either one or both of switches 31 and 32 may be semiconductor switches, and either one or both of switches 33 and 35 may be mechanical contact type switches.

[0055] [Modification of Anode Power Supply] FIG. 2 shows an example of a configuration in which the anode power supply 30 supplies power to the anode 12 of the Hall thruster 10. However, the component of the Hall thruster 10 to which the anode power supply 30 supplies power is not limited to the anode 12. In other words, the anode power supply 30 may be configured to supply power to components of the Hall thruster 10 other than the anode 12. In other words, the anode power supply 30 may be configured to serve as one or more of the power supplies, such as the keeper power supply 40, heater power supply 50, coil power supply 60, and a valve power supply (not shown). FIG. 4 is a diagram showing another example of use and configuration of the power supply device (anode power supply 30) according to the first embodiment.

[0056] 4 shows an example of an anode power supply 30 (hereinafter referred to as "anode power supply 30a") configured to supply power to the anode 12, the keeper electrode body 15b and the heater 15c of the hollow cathode portion 15, and the electromagnet 14. Figure 4 also shows the anode 12, the keeper electrode body 15b, the heater 15c, and the electromagnet 14 to which power is supplied by the anode power supply 30a, as well as a power controller 100 from which the anode power supply 30a receives power. The anode power supply 30a includes, for example, six batteries B (batteries B-1 to B-6), five switches 31 (switches 31-1 to 31-5), a switch 32, a switch 33, a resistor 34, a switch 35, six diodes 36 (diodes 36-1 to 36-6), a diode 37, and three switches 38 (switches 38-1 to 38-3). In the components of the anode power supply 30a, the components that are given the same reference numerals as the components of the anode power supply 30 are similar components, and therefore detailed description thereof will be omitted.

[0057] Each of the switches 38-1 to 38-3 is disposed between the positive terminal of a corresponding series-connected battery B and a corresponding component of the Hall thruster 10. More specifically, the switch 38-1 is disposed between the positive terminal of the series-connected second-stage battery B-2 and the coil positive electrode Em+ of the coil of the electromagnet 14. The switch 38-2 is disposed between the positive terminal of the series-connected second-stage battery B-2 and the heater electrode Eh of the heater 15c. The switch 38-3 is disposed between the positive terminal of the series-connected fourth-stage battery B-4 and the keeper electrode Ek of the keeper electrode body 15b. For example, if the keeper power supply 40 is configured to supply power from the anode power supply 30 to the keeper electrode body 15b by branching the path between the switch 35 for the anode power supply 30 and the anode electrode Ea and connecting an ignition circuit (a circuit that causes discharge between the hollow cathode body 15a and the keeper electrode body 15b) composed of passive elements such as capacitor elements, the switch 38-3 for the keeper power supply 40 may be omitted. The switch 38 controls whether power is supplied from corresponding locations of the series-connected batteries B-1 to B-6 to corresponding components when operating the Hall thruster 10. Like the switch 35, the switch 38 is also a semiconductor switch composed of a semiconductor switching element. Figure 4 also shows the body diode, which is typically included in a metal-oxide-semiconductor field-effect transistor, for the switch 38. The gate terminal of the semiconductor switching element constituting the switch 38 is also controlled (a control voltage or control current is applied) by the battery drive unit BD. At this time, the battery-powered unit BD controls the switch 38 in the same way as the switch 35 with a soft turn-on function, or controls it to switch between an on state and an off state. Here, the control of the battery-powered unit BD to switch between an on state and an off state is equivalent to the control similar to the soft turn-on function, in which the predetermined start-up time is set to 0.

[0058] The battery drive unit BD controls the switches 38 in accordance with the components of the Hall thruster 10 to which power is supplied via each switch 38. More specifically, when the battery drive unit BD outputs power stored in the series battery BS to the electromagnet 14 to operate the Hall thruster 10, the battery drive unit BD controls the gate terminal of the semiconductor switching element of switch 38-1 to turn on the switch 38-1 so that the coil of the electromagnet 14 is connected to both ends of the series-connected batteries B-1 and B-2. As a result, a voltage of 100 V is applied to the coil (coil positive electrode Em+) of the electromagnet 14. When the battery drive unit BD outputs power stored in the series battery BS to the heater 15c to operate the Hall thruster 10, the battery drive unit BD controls the gate terminal of the semiconductor switching element of switch 38-2 to turn on the switch 38-2 so that the heater 15c is connected to both ends of the series-connected batteries B-1 and B-2. As a result, a voltage of 100 V is applied to the heater 15 c (heater electrode Eh). When the battery driver BD outputs power stored in the series-connected battery BS to the keeper electrode main body 15 b to operate the Hall thruster 10, the keeper electrode main body 15 b is connected to both ends of the series-connected batteries B-1 to B-4, and similar to the soft turn-on function, the battery driver BD controls the gate terminal of the semiconductor switching element of the switch 38-3 so that the voltage value changes to its maximum value within a predetermined rise time. As a result, a voltage is applied to the keeper electrode main body 15 b (keeper electrode Ek) that changes from a voltage value of 0 V to a maximum voltage value of 200 V over the predetermined rise time and is maintained at the maximum voltage value of 100 V after the predetermined rise time has elapsed. As a result, the voltage from battery B-4 of the series-connected battery BS is applied to the keeper electrode main body 15 b while suppressing the flow of a large current (inrush current) that would occur if the voltage value were suddenly increased to its maximum value.

[0059] The anode power supply 30a is also an example of a "power supply device." The keeper electrode body 15b, the heater 15c, and the coil of the electromagnet 14 are examples of a "second power supply destination." The switch 38 (each of the switches 38-1 to 38-3) is an example of a "fifth switch unit." The positive terminal of the second-stage battery B-2 connected in series and the positive terminal of the fourth-stage battery B-4 connected in series are examples of a "second positive terminal."

[0060] In this manner, by configuring the Hall thruster 10 to supply power to components other than the anode 12 from corresponding locations of the series-connected batteries B-1 to B-6, the spacecraft equipped with the Hall thruster system 1 including the power processing unit 20 to which the anode power supply 30a is applied can reduce the number of corresponding power supplies, thereby achieving further weight reduction. In the spacecraft equipped with the Hall thruster system 1 including the power processing unit 20 to which the anode power supply 30a is applied shown in Figure 4, the keeper power supply 40 corresponding to the keeper electrode body 15b, the heater power supply 50 corresponding to the heater 15c, and the coil power supply 60 corresponding to the coil of the electromagnet 14 can be eliminated, resulting in a further weight reduction compared to the spacecraft equipped with the Hall thruster system 1 including the power processing unit 20 to which the anode power supply 30 is applied shown in Figure 2. Furthermore, if the anode power supply 30a shown in FIG. 4 is configured to also function as a valve power supply (not shown), that is, to supply power (voltage or current) to a valve arranged in the gas supply pipe 12a to control the opening and closing of the valve, a spacecraft equipped with a Hall thruster system 1 including a power processing unit 20 to which this anode power supply 30a is applied can further reduce the number of valve power supplies (not shown) in addition to the keeper power supply 40, heater power supply 50, and coil power supply 60, thereby further reducing the weight of the spacecraft equipped with the Hall thruster system 1.

[0061] 4 shows a configuration including switches 38, namely, switch 38-1 corresponding to the coil of electromagnet 14, switch 38-2 corresponding to heater 15c, and switch 38-3 corresponding to keeper electrode body 15b, but anode power supply 30a is not limited to a configuration including three switches 38 (switches 38-1 to 38-3). In other words, the configuration is not limited to three switches 38, and may include any one or more switches 38.

[0062] 4 shows an example of the configuration in which the switch 38 is a semiconductor switch. However, the configuration of the switch 38 is not limited to the configuration shown in FIG. 4 as long as it is capable of realizing each of the above-described functions. In other words, any one or more of the switches 38-1 to 38-3 may be mechanical contact type switches. For example, the switches 38-1 and 38-2, which are controlled to switch between an on state and an off state, may be mechanical contact type switches, and the switch 38-3, which is controlled in the same manner as the soft turn-on function, may also be a mechanical contact type switch.

[0063] Second Embodiment [Configuration of Anode Power Supply] The configuration of the anode power supply 30 of the second embodiment will be described below. In the following description, the anode power supply 30 of the second embodiment will be referred to as the "anode power supply 30b." FIG. 5 is a diagram showing an example of the configuration of a power supply device (anode power supply 30b) according to the second embodiment. As with the anode power supply 30 of the first embodiment shown in FIG. 2, FIG. 5 also shows the anode 12 to which the anode power supply 30b supplies power and the power controller 100 from which the anode power supply 30b receives power. The anode power supply 30b includes, for example, six batteries B (batteries B-1 to B-6), five switches 31 (switches 31-1 to 31-5), a switch 33, a resistor 34, a switch 35, six diodes 36 (diodes 36-1 to 36-6), a diode 37, and a switch 39.

[0064] In the anode power supply 30b, the switch 32 included in the anode power supply 30 is replaced with a switch 39. In the anode power supply 30b, the negative terminal of the first-stage battery B-1 of the series-connected batteries BS and the cathode electrode Ec of the Hall thruster 10 are always connected. The other configurations and components of the anode power supply 30b are the same as those of the anode power supply 30 of the first embodiment. Therefore, a repeated description of the other configurations and components included in the anode power supply 30b will be omitted.

[0065] The switch 39 is a switch for exclusively switching whether or not the power controller 100 is connected across the battery B. More specifically, the switch 39 connects the power controller 100 across each of the parallel-connected batteries B when charging each battery B with power supplied by the power controller 100, and disconnects each battery B from the power controller 100 when connecting each battery B in series to operate the Hall thruster 10 and supplying the stored power to the anode 12. In other words, the switch 39 functions to insulate the power controller 100 from the operating Hall thruster 10, similar to the switch 32 included in the anode power supply 30 of the first embodiment. Like the switch 32 included in the anode power supply 30 of the first embodiment, the switch 39 is, for example, a mechanical contact switch. Like the switch 32 included in the anode power supply 30 of the first embodiment, the switching of the connection destination of the switch 39 is controlled, for example, by the battery drive unit BD simultaneously with each of the switches 31-1 to 31-5. That is, when charging each battery B with power supplied by the power controller 100, the battery drive unit BD controls the switch 39 to connect the power controller 100 to both ends of each parallel-connected battery B, and when outputting the power stored in the battery B to operate the Hall thruster 10, it controls the switch 39 to disconnect the power controller 100 from the series-connected batteries B-1 to B-6. As a result, in the anode power supply 30b as well, as in the anode power supply 30 of the first embodiment, it is possible to prevent noise generated in conjunction with discharge occurring between the anode 12 and the hollow cathode body 15a from leaking into and affecting the power controller 100 side. As a result, in the anode power supply 30b, like the anode power supply 30 of the first embodiment, it is possible to obtain power to be supplied to the anode 12 as DC power without converting the DC power supplied by the power controller 100 to AC power, as is the case with anode power supplies provided in conventional Hall thruster systems, and it is possible to isolate the power controller 100 from the operating Hall thruster 10 with a configuration simpler than that of conventional anode power supplies.

[0066] The switch 39 is an example of a "second switch section."

[0067] The control of the anode power supply 30b in the battery-driven unit BD and the operation of the anode power supply 30b can be easily understood from the operation of the anode power supply 30 of the first embodiment explained using Fig. 3, and therefore a detailed description thereof will be omitted. Similar to the anode power supply 30 of the first embodiment explained using Fig. 4, the anode power supply 30b may also be configured to supply power to components other than the anode 12 included in the Hall thruster 10. The configuration in this case can also be easily understood from the modified example of the anode power supply 30 of the first embodiment shown in Fig. 4, and therefore a detailed description thereof will be omitted.

[0068] With this configuration and operation (control of the battery drive unit BD), the anode power supply 30b also connects the batteries B in parallel, similar to the anode power supply 30 of the first embodiment, charges the power (power of the system power supply) supplied by the power controller 100, and connects the batteries B in series (treating them as series batteries BS) to supply power to the anode 12. This allows the anode power supply 30b to more efficiently supply power to the anode 12, similar to the anode power supply 30 of the first embodiment, allowing a high-power Hall thruster 10 to be mounted on a small spacecraft whose system power supply cannot supply much power, and enhancing the advantages of a small spacecraft equipped with a Hall thruster system 1 including a power processing unit 20 to which the anode power supply 30b is applied.

[0069] Although Fig. 5 shows an example of the configuration in which switch 39 is a mechanical contact switch, the configuration of switch 39 is not limited to the configuration shown in Fig. 5 as long as it is capable of realizing each of the above-described functions. For example, switch 39 may be a semiconductor switch.

[0070] As described above, the anode power supply 30 (including the anode power supply 30a and the anode power supply 30b) of the embodiment is provided in the power processing unit 20 of the Hall thruster system 1, instead of the anode power supply provided in the power processing unit in a conventional Hall thruster system. In the anode power supply 30 of the embodiment, the battery B provided in the anode power supply 30 is connected in parallel to charge the power supplied by the power controller 100, and the battery B is connected in series to apply a high voltage to the anode 12. As a result, in the Hall thruster system 1 including the power processing unit 20 to which the anode power supply 30 of the embodiment is applied, when electrons of the propulsion gas are emitted from the hollow cathode portion 15 side to the channel portion 11 side, a discharge occurs between the anode 12 and the hollow cathode body 15a, just as in the conventional Hall thruster system. Furthermore, in the Hall thruster system 1 including the power processing unit 20 to which the anode power supply 30 of the embodiment is applied, as in conventional Hall thruster systems, the propulsion gas is ionized by plasma generated by discharge, and the extracted ions are accelerated by an electric field generated by the anode 12 and the hollow cathode body 15a and ejected into space from the channel unit 11. As a result, the Hall thruster system 1 including the power processing unit 20 to which the anode power supply 30 of the embodiment is applied can also provide thrust to a spacecraft, as in conventional Hall thruster systems. Moreover, because the anode power supply 30 of the embodiment supplies power to the anode 12 from the battery B included in the anode power supply 30, a high-power Hall thruster 10 can be mounted on a small spacecraft without increasing the power of a battery such as a system power supply or a power controller, which would be necessary if an intermittent operation method considered in conventional Hall thruster systems were adopted.

[0071] In the above-described embodiment, the battery-powered unit BD is provided in the anode power supply 30. However, the battery-powered unit BD is not limited to being provided in the anode power supply 30. For example, the battery-powered unit BD may be provided in the power processing unit 20 or the power controller 100. In this case, the configuration of the anode power supply 30 and the control of each switch by the battery-powered unit BD may be equivalent to the configuration of the anode power supply 30 and the control of the battery-powered unit BD in the above-described embodiment. Therefore, detailed description of the configuration of the anode power supply 30 and the control of the battery-powered unit BD in a configuration in which the battery-powered unit BD is provided in the power processing unit 20 or the power controller 100 will be omitted.

[0072] In the above-described embodiment, the anode power supply 30 is described as having six batteries B (batteries B-1 to B-6). However, the number of batteries B included in the anode power supply 30 is not limited to six and may be determined, for example, based on the power supplied by the power controller 100 to the anode power supply 30 and the power supplied by the anode power supply 30 to the anode 12. Even if the anode power supply 30 has a different number of batteries B, the configuration of the anode power supply 30 and the control of each switch by the battery drive unit BD should be equivalent to the configuration of the anode power supply 30 and the control of the battery drive unit BD in the above-described embodiment. Therefore, detailed descriptions of the configuration of anode power supplies 30 having a different number of batteries B and the control of the battery drive unit BD will be omitted.

[0073] In the above-described embodiment, the configuration of each battery B, i.e., the number and connection of battery cells included in battery B, is not particularly described. The number and connection of battery cells included in each battery B may be determined, for example, based on the ion injection time per ion injection in the Hall thruster 10. Here, the ion injection time per ion injection in the Hall thruster 10 is also related to the charge capacity (electrical capacity) of the battery cells. Therefore, the connection method of the battery cells within battery B is not limited to series connection, but may be a combination of series connection and parallel connection so as to increase the electrical capacity of battery B while maintaining the output voltage of battery B constant. For example, consider a case where each battery cell has a voltage value of 3.7 V and an electrical capacity of 1 Ah, and battery B is composed of 20 battery cells. In this case, battery B can be configured as a single battery B with a voltage value of 37 V and an electrical capacity of 20 Ah by connecting two battery cell sets, each of which has 10 battery cells connected in series, in parallel (i.e., each battery cell is configured in a 10-series, 2-parallel configuration). 2 is used to form the anode power supply 30 having the configuration shown in FIG. 2, the anode power supply 30 can supply power to the anode 12 with a maximum voltage of 296 V and a current of 160 Ah. Even in this case, the configuration of the anode power supply 30 and the control of each switch by the battery drive unit BD should be equivalent to the configuration of the anode power supply 30 and the control of the battery drive unit BD in the above-described embodiment. Therefore, detailed description of the configuration of the anode power supply 30 and the control of the battery drive unit BD in this case will be omitted.

[0074] In the above-described embodiment, the anode power supply 30 has been described as being applied to the Hall thruster system 1. However, the electric propulsion system to which the anode power supply 30 is applied is not limited to the Hall thruster system 1. The anode power supply 30 can be applied to any electric propulsion system that ionizes a propulsion gas using plasma generated by discharge (plasma discharge) and ejects the extracted ions into space. In other words, the anode power supply 30 can be used as a power supply that supplies power to at least the components that generate the plasma discharge in any electric propulsion system that involves plasma discharge. For example, the anode power supply 30 can be used in an ion engine as a power supply that supplies power to the components that ionize the propulsion gas and release the extracted ions. In this case, the configuration of the anode power supply 30 and the control of each switch by the battery drive unit BD may be equivalent (compatible with the ion engine) to the configuration of the anode power supply 30 and the control of the battery drive unit BD in the above-described embodiment. Therefore, detailed explanations regarding the configuration of the anode power supply 30 when it is employed in an ion engine and the control of the battery drive unit BD will be omitted.

[0075] The above describes the form for carrying out the present invention using an embodiment, but the present invention is not limited to such an embodiment, and various modifications and substitutions can be made within the scope that does not deviate from the gist of the present invention.

[0076] DESCRIPTION OF SYMBOLS 1...Hall thruster system 10...Hall thruster 11...Channel portion 12...Anode 12a...Gas supply pipe 13...Wall portion 14...Electromagnet 14a...Inner electromagnet 14b...Outer electromagnet 15...Hollow cathode portion 15a...Hollow cathode body 15b...Keeper electrode body 15c...Heater 15d...Gas supply pipe 20...Power processing unit (PPU) 30, 30a, 30b...Anode power supply 31, 31-1, 31-2, 31-2, 31-4, 31-5...Switch 32...Switch 33...Switch 34...Resistor 35...Switch 36, 36-1, 36-2, 36-3, 36-4, 36-5, 36-6...Diode 37...Diode 38, 38-1, 38-2, 38-3...Switch 39...Switch 40...Keeper power supply 50...Heater power supply 60...Coil power supply 100...Power controller 120...Solar cell 140...Battery B, B-1, B-2, B-3, B-4, B-5, B-6, B-n...Batteries BD...Battery drive unit Ea...Anode electrode Ec...Cathode electrode Ek...Keeper electrode Eh...Heater electrode Em+...Coil positive electrode Em-...Coil negative electrode

Claims

1. A power supply device for supplying power to an electric thruster that generates the thrust of a space machine, comprising: a plurality of batteries; a first switch unit provided in plurality for each two adjacent batteries, and switching the connection between the corresponding two batteries to series connection or parallel connection; and a second switch unit for switching whether to connect a power supply source to each of the batteries.

2. The second switch unit switches whether to connect the power supply source to both ends of each of the batteries connected in parallel, or to connect a first positive terminal side including the positive terminal of the last-stage battery connected in series and a first negative terminal which is the negative terminal of the first-stage battery connected in series to a first power supply destination which is a component of the electric thruster. The power supply device according to claim 1.

3. The first positive terminal side including the positive terminal of the last-stage battery connected in series and the first negative terminal which is the negative terminal of the first-stage battery connected in series are connected to a first power supply destination which is a component of the electric thruster. When the electric thruster does not generate the thrust, the second switch unit connects a path in which the first negative terminal and the first power supply destination are connected to the power supply source. When the electric thruster generates the thrust, the second switch unit disconnects the path and the power supply source. The power supply device according to claim 1.

4. A third switch unit for controlling the voltage rise time is further provided between a first positive terminal including the positive terminal of the last-stage battery connected in series and a first power supply destination which is a component of the electric thruster, so that the voltage applied from the batteries connected in series to the first power supply destination becomes the voltage between the first positive terminal which is the maximum voltage in a predetermined time and the first negative terminal which is the negative terminal of the first-stage battery connected in series. The power supply device according to any one of claims 1 to 3.

5. A fourth switch unit that is disposed between the positive electrode terminal of each of the batteries connected in parallel and the power supply source, and that turns off when the voltage corresponding to the power stored in each battery reaches a predetermined voltage, and limits the current flowing from the power supply source to the positive electrode terminal side of each battery when in the on state. The power supply device according to claim 4, further comprising the fourth switch unit.

6. A voltage conversion unit that is disposed before or after the third switch unit and boosts or buck-boosts the voltage between the first positive electrode terminal and the first power supply destination. The power supply device according to claim 5, further comprising the voltage conversion unit.

7. A fifth switch unit that controls the connection between a second positive electrode terminal that is the positive electrode terminal of any stage of the batteries connected in series and a second power supply destination that is a component of the electric thruster. The power supply device according to claim 6, further comprising the fifth switch unit.

8. The electric thruster generates the thrust by injecting ions extracted by ionizing a predetermined gas with plasma generated by a discharge occurring when a high voltage is applied. The power supply device according to claim 7, wherein the electric thruster is an electric thruster that generates thrust by injecting ions extracted by ionizing a predetermined gas with plasma generated by a discharge occurring when a high voltage is applied.

9. The electric thruster is a Hall thruster, and the power supply device is provided in a power processing unit that supplies power to each component of the Hall thruster. The power supply device according to claim 8, wherein the electric thruster is a Hall thruster, and the power supply device is provided in a power processing unit that supplies power to each component of the Hall thruster.

10. The power supply source is a power controller that supplies power from a system power source including a power generation device provided in the spacecraft and / or a battery that stores the power generated by the power generation device to the power processing unit. The first power supply destination is an anode of the Hall thruster. The third switch unit is disposed between the first positive electrode terminal and the anode electrode of the anode. The first negative electrode terminal is connected to the cathode electrode of the hollow cathode of the Hall thruster. The power supply device according to claim 9, wherein the power supply source is a power controller that supplies power from a system power source including a power generation device provided in the spacecraft and / or a battery that stores the power generated by the power generation device to the power processing unit. The first power supply destination is an anode of the Hall thruster. The third switch unit is disposed between the first positive electrode terminal and the anode electrode of the anode. The first negative electrode terminal is connected to the cathode electrode of the hollow cathode of the Hall thruster.

11. The first switch unit and the second switch unit are mechanical contact switches. The power supply device according to claim 10, wherein the first switch unit and the second switch unit are mechanical contact switches.

12. The third switch unit is a semiconductor switch in which a semiconductor switching element and a current rectifying element are connected in parallel. The power supply device according to claim 11, wherein the third switch unit is a semiconductor switch in which a semiconductor switching element and a current rectifying element are connected in parallel.

13. The power supply device according to claim 12, wherein the fourth switch unit is a semiconductor switch in which a semiconductor switching element and a current rectifying element are connected in parallel.

14. The power supply device according to claim 13, wherein the fifth switch unit is a semiconductor switch in which a semiconductor switching element and a current rectifying element are connected in parallel.

15. The second power supply destination is a component other than the anode of the hall thruster, and the fifth switch unit is disposed between the second positive terminal and an electrode of a corresponding component other than the anode. The power supply device according to claim 14.

16. The power supply device according to claim 15, wherein the electrode of the component other than the anode is a keeper electrode of a hollow cathode portion of the hall thruster.

17. The power supply device according to claim 15, wherein the electrode of the component other than the anode is a heater electrode of a heater of a hollow cathode portion of the hall thruster.

18. The power supply device according to claim 15, wherein the electrode of the component other than the anode is a coil electrode of a coil constituting an electromagnet of the hall thruster.

19. The power supply device according to claim 15, wherein the electrode of the component other than the anode is disposed on a gas supply pipe that supplies the predetermined gas to the anode, and is an electrode of a valve that controls at least the presence or absence of supply of the predetermined gas to the anode.

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