Power supply device

Abstract

To provide a power supply device capable of supplying electric power to an electric propulsion machine more efficiently.SOLUTION: Provided is a power supply device that supplies electric power to an electric propulsion machine for generating propulsion force of a spacecraft. The power supply device comprises: a plurality of batteries; a plurality of first switch units, each provided corresponding to each of two adjacent batteries, the switching units switching the connection between the corresponding two batteries to a series connection or a parallel connection; and a second switch unit switching whether or not a power supply source is connected to each of the batteries.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a power supply device.

Background Art

[0002] The use of an electric thruster for generating a propulsive force for controlling the orbit and attitude of spacecraft such as artificial satellites has been expanding, and the market is growing rapidly. Since the electric thruster can reduce the propellant gas to be mounted on the spacecraft as compared with the chemical thruster, it is being increasingly adopted not only for artificial satellites and geostationary satellites for deep space exploration but also for constellation satellites operating in low orbits. In recent years, among electric thrusters, the use of a system using a Hall thruster in particular has been rapidly progressing. This is due to the merit that the Hall thruster system has a high generated thrust per unit power.

[0003] The Hall thruster generates thrust by accelerating ions extracted from plasma generated by ionizing a predetermined gas such as xenon and ejecting them into space. In the Hall thruster system, a discharge is caused in the Hall thruster by the power supplied from the Power Processing Unit (PPU), and ions are extracted from the plasma generated by this discharge. In the Hall thruster system, the power required for the operation of the Hall thruster is supplied to the power processing unit via a power controller from, for example, solar cell paddles (photovoltaic power generation devices) or batteries. Therefore, the power that can be utilized by the Hall thruster depends on the power generated by the spacecraft. On the other hand, generally, the lower the supplied power, the more difficult it is to increase the propulsion efficiency. For this reason, in Hall thrusters with low power in the range of several tens of [W] to several hundreds of [W], the thrust power ratio representing the generated thrust per unit power and the specific impulse equivalent to the fuel consumption indicating how much gas is used are not very high. However, in small spacecraft (e.g., in the 100 [kg] class) that do not generate a large amount of power, it is necessary to select a Hall thruster with low power and low propulsion efficiency. For this reason, in small spacecraft equipped with low-power Hall thrusters, the advantages of the Hall thruster, such as reduction of propulsion gas and high generated thrust per unit power, are small, and there may be cases where the missions that can show superiority over spacecraft equipped with other propulsion systems are limited.

[0004] In order to mount a Hall thruster with a power level (hereinafter referred to as "high-power Hall thruster") that can achieve a high thrust-to-power ratio and high propulsion efficiency, which are the characteristics of a conventional Hall thruster, on a small spacecraft, for example, a power controller supplies the power of a battery, such as a system power supply for operating the spacecraft system, to a power processing unit only for a short time to operate the Hall thruster, and then waits for the supply of power to the power processing unit until the battery is charged, and it is conceivable to adopt an intermittent operation method. However, in order to adopt the intermittent operation method, it is necessary to increase the power of the battery and the power controller. In addition, the power processing unit also has a configuration that can handle high power. Here, the power processing unit is composed of, for example, a plurality of power supplies such as an anode power supply, a keeper power supply, a heater power supply, and a coil power supply, and a power control unit. This power processing unit occupies a large proportion of the weight and cost in the Hall thruster system. Therefore, even if high propulsion efficiency can be obtained by mounting a high-power Hall thruster on a small spacecraft, the overall superiority may be reduced.

[0005] Conventionally, technologies related to miniaturization and cost reduction of power processing units have been proposed. As one of the proposals, there is a technology for miniaturizing an anode power supply that accounts for most of the power supplied to a Hall thruster among a plurality of power supplies constituting the power processing unit. As a technology for miniaturizing the anode power supply, for example, a technology for miniaturization by adopting a resonant converter as the anode power supply (for example, Patent Document 1), or a technology for suppressing the discharge instability peculiar to the Hall thruster by varying the output voltage of the anode power supply at a high frequency and achieving miniaturization of the filter provided in the anode power supply (for example, Patent Document 2) have been proposed. As another proposal, among a plurality of power supplies constituting the power processing unit, a technology has been proposed to eliminate (delete) the heater power supply of the hollow cathode provided in the Hall thruster and start discharge in the hollow cathode by applying a high-voltage pulse generated by a keeper power supply (for example, Patent Document 3). In this conventional technology, the electron-emitting material is not heated by the heater power supply, but electrons are strongly drawn out from the hollow cathode by the high-voltage pulse generated by the keeper power supply, and discharge and plasma are generated between the hollow cathode and the keeper electrode.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the prior art where the size and cost of the power processing unit are reduced by miniaturizing the anode power supply, in order to miniaturize the anode power supply, which is an essential power supply for accelerating and injecting gas in the Hall thruster, for example, it is necessary to improve the power density of the anode power supply. As a result, another problem may arise in order to ensure the performance of the Hall thruster system, such as the need to improve the power density of the anode power supply. On the other hand, in the prior art where the size and cost of the power processing unit are reduced by eliminating the heater power supply, for example, it is necessary to suppress the material loss of the keeper electrode (or the end portion on the keeper electrode side of the hollow cathode) due to the arc of the high-voltage pulse generated by the keeper power supply, and the decrease in insulation between the electrodes due to the material loss. As a result, another problem may arise in order to continue the operation of the Hall thruster system, such as the need to suppress the material loss of the keeper electrode and the decrease in insulation between the electrodes due to the material loss. Therefore, in the prior art, when considering the mission to be performed by the spacecraft, it may be difficult to show superiority by mounting a high-power Hall thruster on a small spacecraft.

[0008] The present invention has been made based on the above recognition of the problems, and an object thereof is to provide a power supply device that can supply power to an electric thruster more efficiently.

Means for Solving the Problems

[0009] In order to achieve the above object, a power supply device according to an aspect of the present invention is a power supply device that supplies power to an electric thruster that generates the propulsion force of a spacecraft, and includes a plurality of batteries, a plurality of first switch units provided corresponding to each pair of adjacent batteries, and configured to switch the connection between the corresponding two batteries to a series connection or a parallel connection, and a second switch unit configured to switch whether or not to connect a power supply source to each battery.

Effects of the Invention

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

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the power supply device of the present invention will be described with reference to the drawings. The power supply device of the present invention is applied to a system of an electric thruster. The system of the electric thruster may be a Hall thruster system including a Hall thruster, or may be an ion engine system including an ion engine. In the following description, the case where the system of the electric thruster is a Hall thruster system including a Hall thruster will be described as an example.

[0013] A Hall thruster is an electric thruster that, for example, accelerates ions drawn from plasma generated by ionizing a predetermined gas (propulsion gas) such as xenon and injects them into space, thereby controlling the orbit of a spacecraft when moving in space or controlling the attitude of the spacecraft to generate a propulsive force. The propulsion gas may be, for example, a gas such as krypton, argon, nitrogen, oxygen, vaporized iodine, or water.

[0014] A spacecraft equipped with a Hall thruster system may be an artificial satellite that orbits along a predetermined orbit over the Earth's surface or over the surface of other celestial bodies or objects, or it may be an observation satellite that travels to observe other celestial bodies or objects (and may also return to Earth). Other celestial bodies include other planets different from the Earth, such as Mars and Venus, satellites such as the Moon and Titan, and asteroids such as Itokawa and Ryugu. Other objects include rocks and the like.

[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 having 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: Power Processing Unit) 20. FIG. 1(a) shows an example when viewed from the side where the Hall thruster 10 ejects ions drawn from propellant gas into plasma into outer space. FIG. 1(b) shows an example of a cross-sectional view of the Hall thruster 10 taken along the A-A' cross-section shown in FIG. 1(a), and an example of the connection between the Hall thruster 10 and the power processing unit 20. FIG. 1(c) shows an example of the configuration of the Hall thruster system 1.

[0016] First, the structure of the Hall thruster 10 will be described with reference to FIGS. 1(a) and 1(b). In the Hall thruster 10, a hollow cathode portion 15 is disposed at the center of a cylindrical housing, and an internal electromagnet 14a, a channel portion 11, and an external electromagnet 14b are annularly arranged in this order from the center toward the outer peripheral portion. In the following description, when the internal electromagnet 14a and the external electromagnet 14b are not distinguished from each other, they are simply referred to as "electromagnet 14". In the Hall thruster 10, the channel portion 11 is formed as a groove along the electromagnet 14, and the periphery of the groove is surrounded by a wall portion 13 made of, for example, ceramic. And an anode 12 is disposed at the bottom of the groove forming the channel portion 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 with reference to FIGS. 1(b) and 1(c). FIG. 1(c) also shows the components of the spacecraft 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. The power controller 100 supplies, for example, power converted to the required voltage value and current value for each component to each component. The solar cell 120 is, for example, a system power source that outputs the power generated by the solar cell paddles (solar power generation devices) of the spacecraft. The battery 140 is a storage battery of the system power source that stores the power supplied by the power controller 100 and supplies the stored power to the power controller 100 in response to the control from the power controller 100. The power controller 100 may supply the power output by the solar cell 120 to each component of the spacecraft, or store the power output by the solar cell 120 in the battery 140, and supply power from the battery 140 as needed to supply power to each component of the spacecraft. In the following description, when the solar cell 120 and the battery 140 are not distinguished, it is referred to as "system power source".

[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 examples of "system power sources".

[0019] As described above, the Hall thruster 10 includes, for example, a channel portion 11, an anode 12, a wall portion 13, an electromagnet 14, and a 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 component 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. Each of the anode power supply 30, the keeper power supply 40, the heater power supply 50, and the coil power supply 60 is a DC power supply that supplies the necessary power to the corresponding component included in 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 value of 300 [V] and a current value of 3 [A]. In this case, a Hall thruster 10 of the 1 [kW] class is configured. The anode power supply 30 may supply power to the anode 12 with a maximum voltage value of 300 [V] and a current value of 20 [A]. In this case, a Hall thruster 10 of the 6 [kW] class is configured. The power supplied by the anode power supply 30 is not limited to a maximum voltage value = 300 [V]. The anode power supply 30 may supply power with a maximum voltage value of 150 [V] or 1000 [V], etc., depending on the performance of the Hall thruster 10, for example. The anode power supply 30 includes a plurality of batteries B and a battery drive unit BD. Figure 1(c) shows an example of a configuration in which the anode power supply 30 includes n (n is a natural number) batteries B of battery B-1 to battery B-n. 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. Details regarding 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, for example, with a voltage value of 200 [V] and a current value of 1 [A] to the keeper electrode body 15b. In Fig. 1(c), a configuration is shown 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), but the negative electrode side of the keeper power supply 40 may be connected to a dedicated electrode provided in the hall thruster 10, for example. The keeper power supply 40 may be omitted, for example, when the power supply 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 power, for example, with a voltage value of 100 [V] and a current value of 1 [A], power with a voltage value of 10 [V] and a current value of 10 [A], or power with a voltage value of 20 [V] and a current value of 5 [A] to the heater 15c. In Fig. 1(c), a configuration is shown in which the negative electrode side of the heater power supply 50 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), but the negative electrode side of the heater power supply 50 may be connected to a dedicated electrode provided in the hall thruster 10, for example. 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 electromagnet 14 (more specifically, the coils constituting the internal electromagnet 14a and the external electromagnet 14b, respectively). The coil power supply 60 supplies power, for example, with a voltage value of 100 [V] and a current value of 1 [A], power with a voltage value of 10 [V] and a current value of 10 [A], or power with a voltage value of 20 [V] and a current value of 5 [A] to each electromagnet 14.

[0025] The keeper power supply 40, the heater power supply 50, and the coil power supply 60 may be DC power supplies with a fixed voltage value and a fixed current value whose power output on and off is controlled according to the control from, for example, a 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 switching power supplies whose supplied voltage value and current value are controlled according to the 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 supplies electrons for starting the operation of the Hall thruster 10 by ionizing the propellant gas supplied into the channel portion 11 and extracting ions, and during the operation of the Hall thruster 10, it is an electron source that emits electrons for electrically neutralizing the plasma and the accelerated ions. The same propellant gas as that supplied to the anode 12 is supplied to the hollow cathode body 15a from the gas supply pipe 15d. The hollow cathode body 15a ionizes the propellant gas supplied by the gas supply pipe 15d and emits the generated electrons toward the channel portion 11 side. The negative side of the anode power supply 30 is connected to the cathode electrode Ec connected to the hollow cathode body 15a. In Fig. 1(b), an example is shown in which the cathode electrode Ec is arranged on the side of the housing of the Hall thruster 10 opposite to the side where the ions extracted from the plasma are ejected into outer space, but the hollow cathode body 15a itself (which may be the portion of the gas supply pipe 15d) may serve as the cathode electrode Ec. The keeper electrode body 15b is arranged close 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. Further, the outer periphery of the hollow cathode body 15a is covered with the heater 15c. The positive side of the heater power supply 50 is connected to the heater electrode Eh connected to the heater 15c. That is, 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 according to the electric power supplied by the heater power supply 50, heats components called emitters or electron emission materials (not shown) provided in the hollow cathode body 15a, and causes more electrons to be emitted from the hollow cathode body 15a. The positive side of the keeper power supply 40 is connected to the keeper electrode Ek connected to the keeper electrode body 15b. That is, 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 the power supplied by the keeper power supply 40, a discharge occurs between the hollow cathode body 15a and the keeper electrode body 15b. Due to this discharge, the propellant gas supplied from the gas supply pipe 15d into the hollow cathode body 15a is ionized to generate 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 part 11 side.

[0027] The anode 12 is an anode for ionizing the propellant gas supplied into the channel part 11 by the gas supply pipe 12a and extracting ions. Whether the propellant gas is supplied into the channel part 11 by the gas supply pipe 12a and the supply amount of the propellant gas are, for example, controlled by controlling the opening and closing of a valve arranged 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 arranged in the gas supply pipe 12a by controlling the voltage value and current value supplied from the valve power supply (not shown) to the valve. The positive electrode side of the 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). In Fig. 1(b), an example is shown in which, similar to the cathode electrode Ec, the anode electrode Ea is arranged at the end of the housing of the hall thruster 10, but the anode 12 itself may serve as the anode electrode Ea.

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

[0029] The electromagnet 14 generates a magnetic field within the range where the anode 12 is disposed and surrounded by the wall portion 13. The electromagnet 14 has a structure in which a coil is wound around a core material made of a magnetic material. The positive electrode side of the coil power supply 60 is connected to the coil positive electrode Em+ connected to the positive electrode side terminal of the coil. The negative electrode side of the coil power supply 60 is connected to the coil negative electrode Em- connected to the negative electrode side terminal of the coil. The electromagnet 14 generates a magnetic field within the channel portion 11 in response to the power supplied to the coil by the coil power supply 60. In FIG. 1, although the detailed connection between the coil power supply 60 and the coil is omitted, the power from the coil power supply 60 is supplied to each of the coils of the internal electromagnet 14a and the external electromagnet 14b. For example, the power from the coil power supply 60 is supplied to each of the coils of the internal electromagnet 14a and the external electromagnet 14b through a path that returns from the positive electrode side of the coil power supply 60, via the coil positive electrode Em+, the positive electrode side terminal of the coil of the external electromagnet 14b, the negative electrode side terminal of the coil of the external electromagnet 14b, the positive electrode side terminal of the coil of the internal electromagnet 14a, the negative electrode side terminal of the coil of the internal electromagnet 14a, and the coil negative electrode Em- to the negative electrode side of the coil power supply 60. The coil positive electrode Em+ and the coil negative electrode Em- are not limited to a configuration corresponding to each of the coils of the internal electromagnet 14a and the external electromagnet 14b. For example, it may have a configuration including the coil positive electrode Em+ and the coil negative electrode Em- corresponding to the coil of the internal electromagnet 14a and the coil positive electrode Em+ and the coil negative electrode Em- corresponding to the coil of the external electromagnet 14b, that is, a configuration in which the coil positive electrode Em+ and the coil negative electrode Em- are separately provided one by one for each of the coils of the internal electromagnet 14a and the external electromagnet 14b. Further, 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, it may have a configuration in which the power processing unit 20 does not include the coil power supply 60 (therefore, the coil positive electrode Em+ and the coil negative electrode Em- are not provided). In this case, for example, each of the coils of the internal electromagnet 14a and the external electromagnet 14b may be connected between the hollow cathode body 15a and the cathode electrode Ec.More specifically, power may be supplied to each of the coil of the internal electromagnet 14a and the coil of the external electromagnet 14b by connecting them 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 from the hollow cathode body 15a. In this case, when the hollow cathode body 15a draws ions from the propellant gas supplied to the plasma in the channel portion 11, the electromagnet 14 causes a magnetic field corresponding to the power supplied to the coil to be generated in the channel portion 11 by also passing the current flowing at that time through the coil.

[0030] In the Hall thruster 10, the anode 12 and the hollow cathode body 15a are insulated from each other. In the Hall thruster 10, when electrons are drawn from the propellant gas ionized by the plasma generated by the discharge between the hollow cathode body 15a and the keeper electrode body 15b and released to the channel portion 11 side while the generation of the magnetic field in the channel portion 11 by the electromagnet 14 and the application of a high voltage to the anode 12 by the power supplied by the anode power supply 30 occur in this order, in the reverse order, or simultaneously, a discharge occurs between the anode 12 and the hollow cathode body 15a. This discharge ionizes the propellant gas supplied from the gas supply pipe 12a into the channel portion 11 to generate plasma. In the Hall thruster 10, ions are accelerated and drawn from the plasma by the potential gradient inside the generated plasma and are ejected from the channel portion 11 into outer 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 shows together the anode 12 which is the power supply destination to which the anode power supply 30 supplies power, and the power controller 100 which is the power supply source from which the anode power supply 30 receives power supply. 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 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 switches 31-1 to 31-5 is, for example, a mechanical contact type switch. Each of switches 31-1 to 31-5 switches the connection between the corresponding two batteries B to either a series connection or a parallel connection. For example, switch 31-1 corresponds to battery B-1 and battery B-2, and by connecting the positive terminal of battery B-1 and the negative terminal of battery B-2, battery B-1 and battery B-2 are connected in series, and by connecting the negative terminals of battery B-1 and battery B-2, battery B-1 and battery B-2 are connected in parallel. For example, switch 31-2 corresponds to battery B-2 and battery B-3, and similarly to switch 31-1, battery B-2 and battery B-3 are connected in series or in parallel. The same applies to each of switches 31-3 to 31-5. The switching of the connection of the corresponding battery B in each of switches 31-1 to 31-5 is controlled, for example, by battery drive unit BD. When battery drive unit BD stores (charges) the power supplied to each battery B by power controller 100, it controls each switch 31 so that the respective batteries B are connected in parallel, and when outputting the power stored in battery B to operate hall thruster 10, it controls each switch 31 so that the respective batteries B are connected in series.

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

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

[0036] Switch 32 also operates as a function to insulate the power controller 100 from the operating Hall thruster 10. This is because, generally in a Hall thruster including the Hall thruster 10, when a discharge occurs between the anode 12 and the hollow cathode body 15a, noise is generated along with this discharge. When the switch 32 supplies the power stored by connecting the respective batteries B in series to the anode 12 in order to operate the Hall thruster 10, for example, the battery drive unit BD controls the switch 32 simultaneously with each of the switches 31-1 to 31-5, thereby disconnecting each battery B from the power controller 100. As a result, in the anode power supply 30, it is possible to suppress the noise generated along with the discharge that occurred between the anode 12 and the hollow cathode body 15a from reaching the power controller 100 side and having an impact. Even in the anode power supply provided in a conventional Hall thruster system, it is similarly possible to insulate the power controller from the operating Hall thruster. For example, the DC power supplied by the power controller is converted into AC power by a switching circuit or the like, the voltage is converted (boosted) by a transformer or the like, and then rectified by a rectifying circuit or the like to be converted back into DC power before being supplied to the anode. In contrast, in the anode power supply 30, as described above, by simply switching the switch 32, the power controller 100 can be disconnected from each battery B, in other words, from the anode 12. Therefore, with a simpler configuration than a conventional anode power supply, the power controller 100 can be insulated from the operating Hall thruster 10. That is, in the anode power supply 30, it is possible to obtain the power to be supplied to the anode 12 as DC power without performing operations such as converting the DC power supplied by the power controller 100 into AC power.

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

[0038] Switch 33 is a switch arranged between the positive terminal of each battery B and the power controller 100 to control the charging of the power supplied by the power controller 100 to each battery B. The switch 33 is a semiconductor switch composed of a semiconductor switching element such as an N-channel metal oxide semiconductor field effect transistor (MOSFET), for example. FIG. 2 also shows the parasitic diode (so-called body diode) generally provided in the metal oxide semiconductor field effect transistor. The gate terminal of the semiconductor switching element constituting 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 by the battery drive unit BD to be either in an on state or an off state. When the battery drive unit BD charges each battery B with the power supplied by the power controller 100, the switch 33 is controlled to be in the on state, and 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 the charging of each battery B is completed, the switch 33 is controlled to be in the off state. The switch 33 controlled to be in the on state also operates as a function of limiting the current flowing from the power controller 100 to each battery B side.

[0039] Switch 33 is an example of the "fourth switch section".

[0040] Resistor 34 is a resistive element for limiting the current flowing from the power controller 100 to each battery B when charging each battery B with the power supplied by the power controller 100. The resistor 34 limits the current flowing from the power controller 100 to each battery B (lowers the current value) as 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 becomes smaller, that is, as the state of charge of each battery B approaches the fully charged state. Thereby, in the anode power supply 30, the safety during charging each battery B by the power controller 100 can be enhanced. In the anode power supply 30, the resistor 34 may be omitted.

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

[0042] Switch 35 is arranged between the positive terminal of the final-stage battery B-6 connected in series and the anode electrode Ea of the anode 12, and is a switch for controlling so that the voltage value corresponding to the power supplied from the batteries B-1 to B-6 connected in series to the anode 12 does not suddenly reach the maximum value when operating the Hall thruster 10. Here, the maximum value of the voltage value corresponding to the power supplied to the anode 12 is the voltage value between the negative terminal of the lowermost (first-stage) battery B-1 connected in series and the positive terminal of the uppermost (final-stage) battery B-6. Similar to switch 33, switch 35 is also a semiconductor switch composed of a semiconductor switching element. FIG. 2 also shows the body diode generally provided in a metal-oxide-semiconductor field-effect transistor even in switch 35. The gate terminal of the semiconductor switching element constituting switch 35 is also controlled (a control voltage or a control current is applied) by the battery drive unit BD. However, the battery drive unit BD controls the gate terminal of the semiconductor switching element so that the time for the voltage value applied from the batteries B connected in series to the anode 12 to change from 0 [V] to the maximum value, that is, the so-called voltage rise time, becomes a predetermined time. More specifically, when starting the power supply from the batteries B connected in series to the anode 12, the battery drive unit BD repeats the control to turn on switch 35 and the control to turn off switch 35 at a predetermined time period, and controls the gate terminal of the semiconductor switching element so that the on state of switch 35 is maintained when a predetermined time for reaching the maximum value of the voltage value has elapsed. At this time, the battery drive unit BD sequentially lengthens the time for controlling switch 35 to the on state (sequentially shortens the time for controlling to the off state) for each predetermined time period. In other words, the battery drive unit BD controls switch 35 in the same manner as the so-called soft turn-on function to control the voltage rise time of the voltage applied to the anode 12. Thereby, it is possible to suppress a large current (inrush current) from flowing as when the voltage value suddenly reaches the maximum value, and apply the voltage from the batteries B connected in series.

[0043] The switch 35 is an example of the "third switch section".

[0044] Each of the diodes 36-1 to 36-6 is a rectifying element that allows or blocks the current flowing between the corresponding batteries 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 batteries B-1 to B-6 from flowing to the power controller 100 side. Thereby, in the anode power supply 30, the safety when supplying power from the batteries B-1 to B-6 connected in series to the anode 12 can be enhanced. In the anode power supply 30, instead of each of the diodes 36-1 to 36-6, a mechanical contact type switch or a semiconductor switch may be used in a configuration that blocks the current of the power charged in the corresponding batteries B-1 to B-6 from flowing to the power controller 100 side. In this case, the battery drive unit BD may control whether to allow or block the current flowing 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 the current flowing 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 to the power controller 100 side. Thereby, in the anode power supply 30, the safety when supplying power from the batteries B-1 to B-6 connected in series to the anode 12 can be enhanced. In the anode power supply 30, the diode 37 may be omitted.

[0046] In the configuration of the anode power supply 30 shown in FIG. 2, for example, when supplying power from the batteries B-1 to B-6 connected in series to the anode 12, it is conceivable to further increase or decrease the voltage value of the voltage applied to the anode 12. In this case, the anode power supply 30 may be provided with a voltage conversion circuit for boosting or bucking the voltage, such as a DC-DC converter, between the positive terminal of the final-stage battery B-6 connected in series and the switch 35 (i.e., the stage before the switch 35), or between the switch 35 and the anode electrode Ea of the anode 12 (i.e., the stage after the switch 35). The configuration and operation of the anode power supply 30 in this case can be easily considered from the configuration and operation of the anode power supply 30 described above, so detailed description is 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 the case of mounting a Hall thruster 10 of, for example, a power level of 1 [kW] (hereinafter also referred to as the "high-power Hall thruster 10") on a small spacecraft, which can achieve a high thrust-to-power ratio and high propulsion efficiency, which are the characteristics of the original Hall thruster. More specifically, an example will be described in the case where the power controller 100 supplies power with a voltage value of 50 [V] and a current value of 1 [A] to the anode power supply 30 provided in the power processing unit 20, and the anode power supply 30 supplies power with a maximum voltage value of 300 [V] and a current value of 3 [A] to the anode 12. Here, it is assumed that the charge capacity of each battery B corresponds to the power with a voltage value of 50 [V] and a current value of 1 [A] supplied by the power controller 100 to the anode power supply 30.

[0049] FIG. 3 is a diagram showing an example of the operation of the power supply device (anode power supply 30) according to the first embodiment. FIG. 3(a) shows the operation of the anode power supply 30 when charging (storing) the power supplied by the power controller 100 in the battery B, and FIG. 3(b) 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 charging (storing) the power supplied by the power controller 100 in the battery B, the battery drive unit BD connects the respective batteries B in parallel and controls the respective 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. 3(a), the negative terminals of the respective batteries B are connected to each other, and further, 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. Then, the battery drive unit BD controls the switch 33 to be in the on state. FIG. 3(a) shows a state in which power with a voltage value = 50 [V] and a current value = 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 terminals of the respective batteries B via the diodes 37, resistors 34, switch 33, and corresponding diodes 36, and the power supplied by the power controller 100 is charged in each battery B. More specifically, in the configuration of the anode power supply 30 shown in FIG. 2, since there are six batteries B of batteries B-1 to B-6, a current of 1 / 6 [A] flows through each battery B, and the power supplied by the power controller 100 is charged. Thereafter, the battery drive unit BD controls the switch 33 to be in the off state when the voltage value corresponding to the power stored in each battery B becomes equal to the voltage value = 50 [V] output by the power controller 100. Thereby, the charging of the power supplied by the power controller 100 to each battery B is completed.

[0051] When the battery drive unit BD outputs the power stored (charged) in the battery B to operate the Hall thruster 10, the battery drive unit BD connects the respective batteries B in series and controls each switch 31 and switch 32 so that the power is supplied to the anode 12 as if each battery B is one battery (hereinafter referred to as "series battery BS"). As a result, in the anode power supply 30, as shown in Fig. 3(b), each battery B is connected between the positive and negative terminals of adjacent batteries B, and furthermore, each of switches 31-1 to 31-5 and switch 32 is switched so that the anode 12 is connected to both ends of the series battery BS. More specifically, switch 32 is switched so that the positive terminal of the last-stage 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-stage 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. Then, the battery drive unit BD controls switch 35 in the same manner as the soft turn-on function. As a result, a voltage that changes from a voltage value = 0 [V] to a maximum voltage value of 300 [V] in a predetermined rise time and is maintained at the maximum voltage value when the predetermined rise time has elapsed is applied to the anode 12. Fig. 3(b) shows a state in which power with a voltage value = 300 [V] and a current value = 3 [A] is supplied from the series battery BS to the anode 12 via switch 35. Here, in Fig. 3(b), it is assumed that a current with a current value = 3 [A] flows from the series battery BS to the anode 12, but the actual current value of the current flowing through the anode 12 is a current value corresponding to the load characteristics of the plasma in the channel portion 11. Thereby, the Hall thruster 10 ionizes the propellant gas by the plasma, extracts the ions, and ejects them into outer space to generate the propulsion force of the spacecraft.

[0052] With such a configuration and operation (control of the battery drive unit BD), in the anode power supply 30, the respective batteries B are connected in parallel to charge the power supplied by the power controller 100 (the power of the system power supply), and the respective batteries B are connected in series (assuming it is a series battery BS) to supply power to the anode 12. As a result, the anode power supply 30 can supply power to the anode 12 more efficiently, and it is possible to mount a high-power Hall thruster 10 having a high thrust power ratio representing the generated thrust per unit power and a specific impulse equivalent to fuel consumption indicating how much propellant gas is used on a small spacecraft with a small amount of power that can be supplied by the system power supply. This can enhance the superiority of a small spacecraft equipped with the Hall thruster system 1 including the power processing unit 20 to which the anode power supply 30 is applied. More specifically, since the high-power Hall thruster 10 has a higher thrust power ratio and specific impulse than a low-power Hall thruster, when moving the spacecraft in the same manner with the high-power Hall thruster 10 and the low-power Hall thruster, the amount of propellant gas, which occupies a relatively large proportion of the spacecraft's weight, can be reduced. In other words, when the amount of change in speed required for the movement of 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 change in the speed of the spacecraft can be increased. This leads to an expansion of the scope of the mission performed by the spacecraft.

[0053] And, for example, when considering mounting a high-power Hall thruster of about 1 [kW] on a small spacecraft based on the conventional concept, it is necessary to increase the power of the battery and the power controller corresponding to the battery 140. However, with the anode power supply 30, a high-power Hall thruster 10 can be realized without increasing the power of the battery 140 and the power controller 100. That is, by configuring the anode power supply 30 provided in the power processing unit 20 to include the battery B, the battery 140 and the power controller 100 remain in a configuration equivalent to the conventional one without increased power. Therefore, even if the power processing unit 20 is slightly larger in size than the conventional power processing unit, for example, the overall configuration of the high-power Hall thruster 10 of about 1 [kW] can be miniaturized and can be mounted on a small spacecraft. Moreover, in comparison with the conventional power processing unit with increased capacity and the power processing unit 20, the shorter the ion ejection time per shot in the high-power Hall thruster 10, the smaller the charging capacity of the battery B can be, so the power processing unit 20 has an advantage. Further, the switching power supplies that make up each power supply of the conventional power processing unit with increased capacity generate switching noise even at timings unrelated to the discharge or the plasma generated by this discharge. Therefore, the anode power supply 30 configured with the battery B also has an advantage from the perspective of noise.

[0054] In FIG. 2, an example of the configuration is shown in the case where the switch 31 and the switch 32 are mechanical contact switches and the switch 33 and the switch 35 are semiconductor switches. However, the configurations of the switch 31, the switch 32, the switch 33, and the switch 35 are not limited to the configuration shown in FIG. 2 as long as they can realize the respective functions described above. For example, either one or both of the switch 31 and the switch 32 may be semiconductor switches, or either one or both of the switch 33 and the switch 35 may be mechanical contact switches.

[0055] [Modified Example 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 included in 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. That is, the anode power supply 30 may be configured to supply power to components other than the anode 12 included in the Hall thruster 10. In other words, the anode power supply 30 may be configured to also serve as any one or more of power supplies such as the keeper power supply 40, the heater power supply 50, the coil power supply 60, and a valve power supply (not shown). FIG. 4 is a diagram showing another usage example and an example of a configuration in the power supply device (anode power supply 30) according to the first embodiment.

[0056] FIG. 4 shows an example of an anode power supply 30 (hereinafter referred to as "anode power supply 30a") configured to supply corresponding power to the keeper electrode body 15b and the heater 15c included in the hollow cathode section 15 and the electromagnet 14, in addition to the anode 12. FIG. 4 shows together the anode 12, the keeper electrode body 15b, the heater 15c, and the electromagnet 14, which are the power supply destinations to which the anode power supply 30a supplies power, and the power controller 100, which is the power supply source from which the anode power supply 30a receives power supply. 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). Among the components of the anode power supply 30a, each component assigned the same reference numeral as the component of the anode power supply 30 is a similar component, and thus a detailed description thereof will be omitted again.

[0057] Each of switches 38-1 to 38-3 is disposed between the positive terminal of the corresponding battery B connected in series and the component of the corresponding hall thruster 10. More specifically, switch 38-1 is disposed between the positive terminal of the second-stage battery B-2 connected in series and the coil positive electrode Em+ of the coil of the electromagnet 14. Switch 38-2 is disposed between the positive terminal of the second-stage battery B-2 connected in series and the heater electrode Eh of the heater 15c. Switch 38-3 is disposed between the positive terminal of the fourth-stage battery B-4 connected in series and the keeper electrode Ek of the keeper electrode body 15b. When the keeper power supply 40 branches the path between, for example, the switch 35 for the anode power supply 30 and the anode electrode Ea and connects a firing circuit (a circuit that causes discharge between the hollow cathode body 15a and the keeper electrode body 15b) constituted by a passive element such as a capacitor element, the switch 38-3 for the keeper power supply 40 may be omitted. The switch 38 is a switch for controlling whether to supply power from the corresponding locations of the batteries B-1 to B-6 connected in series to the corresponding components when operating the hall thruster 10. Similar to the switch 35, the switch 38 is also a semiconductor switch constituted by a semiconductor switching element. FIG. 4 also shows the body diode generally provided in the metal oxide semiconductor field effect transistor in the switch 38 as well. The gate terminal of the semiconductor switching element constituting the switch 38 is also controlled (a control voltage or a control current is applied) by the battery drive unit BD. At this time, the battery drive unit BD controls the switch 38 in the same manner as the soft turn-on function like the switch 35, or controls it to switch between the on state and the off state. Here, the control for switching between the on state and the off state of the switch 38 in the battery drive unit BD is equivalent to the case where the predetermined rise time = 0 in the control similar to the soft turn-on function.

[0058] The battery drive unit BD controls the switch 38 according to the components of the hall thruster 10 that supply power via each switch 38. More specifically, when the battery drive unit BD outputs the power stored in the series battery BS to the electromagnet 14 to operate the hall thruster 10, it controls the gate terminal of the semiconductor switching element of the switch 38-1 so that the coil of the electromagnet 14 is connected to both ends of the serially connected batteries B-1 to B-2, turning the switch 38-1 on. As a result, a voltage with a voltage value of 100 [V] is applied to the coil (coil positive electrode Em+) of the electromagnet 14. When the battery drive unit BD outputs the power stored in the series battery BS to the heater 15c to operate the hall thruster 10, it controls the gate terminal of the semiconductor switching element of the switch 38-2 so that the heater 15c is connected to both ends of the serially connected batteries B-1 to B-2, turning the switch 38-2 on. As a result, a voltage with a voltage value of 100 [V] is applied to the heater 15c (heater electrode Eh). When the battery drive unit BD outputs the power stored in the series battery BS to the keeper electrode body 15b to operate the hall thruster 10, the keeper electrode body 15b is connected to both ends of the serially connected batteries B-1 to B-4, and the gate terminal of the semiconductor switching element of the switch 38-3 is controlled so that the voltage value changes to the maximum value in a predetermined start-up time, similar to the soft turn-on function. As a result, a voltage that changes from a voltage value of 0 [V] to a maximum voltage value of 200 [V] in a predetermined start-up time and is maintained at a maximum voltage value of 100 [V] when the predetermined start-up time has elapsed is applied to the keeper electrode body 15b (keeper electrode Ek). As a result, the voltage from the battery B-4 of the series battery BS is applied to the keeper electrode body 15b in a state where a large current (inrush current) like when the voltage value is suddenly maximized is suppressed.

[0059] The anode power source 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 section". The positive electrode terminal of the second-stage battery B-2 connected in series and the positive electrode terminal of the fourth-stage battery B-4 connected in series are examples of a "second positive electrode terminal".

[0060] In this way, in a spacecraft equipped with the Hall thruster system 1 including the power processing unit 20 to which the anode power source 30a is applied, by configuring to supply power from the corresponding locations of the batteries B-1 to B-6 connected in series to components other than the anode 12 provided in the Hall thruster 10, the corresponding power supplies can be reduced and the weight can be further reduced. In a spacecraft equipped with the Hall thruster system 1 including the power processing unit 20 to which the anode power source 30a shown in FIG. 4 is applied, the keeper power source 40 corresponding to the keeper electrode body 15b, the heater power source 50 corresponding to the heater 15c, and the coil power source 60 corresponding to the coil of the electromagnet 14 can be reduced, and the weight can be further reduced compared to a spacecraft equipped with the Hall thruster system 1 including the power processing unit 20 to which the anode power source 30 shown in FIG. 2 is applied. Further, when the anode power source 30a shown in FIG. 4 is configured to also have the function of a valve power source not shown, that is, when configured to supply power (voltage or current) to the valve disposed in the gas supply pipe 12a to control the opening and closing of the valve, in a spacecraft equipped with the Hall thruster system 1 including the power processing unit 20 to which this anode power source 30a is applied, in addition to the keeper power source 40, the heater power source 50, and the coil power source 60, a valve power source not shown can be further reduced, and the weight of the spacecraft equipped with the Hall thruster system 1 can be further reduced.

[0061] In the anode power supply 30a shown in FIG. 4, a configuration is shown that includes respective switches 38 such as a switch 38-1 corresponding to the coil of the electromagnet 14, a switch 38-2 corresponding to the heater 15c, and a switch 38-3 corresponding to the keeper electrode body 15b. However, the anode power supply 30a is not limited to a configuration including three switches 38 (switches 38-1 to 38-3). That is, it is not limited to a configuration including three switches 38, and may be a configuration including any one or a plurality of switches 38.

[0062] In FIG. 4, an example of a configuration when the switch 38 is a semiconductor switch is shown. However, the configuration of the switch 38 is not limited to the configuration shown in FIG. 4 as long as it can realize the respective functions described above. That is, any one or a plurality of switches 38-1 to 38-3 may be mechanical contact type switches. For example, the switches 38-1 and 38-2 that are controlled to switch between the on state and the off state may be mechanical contact type switches, and the switch 38-3 that is controlled in the same manner as the soft turn-on function may be a mechanical contact type switch.

[0063] <Second Embodiment> [Configuration of Anode Power Supply] Hereinafter, the configuration of the anode power supply 30 of the second embodiment will be described. In the following description, the anode power supply 30 of the second embodiment is referred to as "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. In FIG. 5, similar to the anode power supply 30 of the first embodiment shown in FIG. 2, an anode 12 that is a power supply destination to which the anode power supply 30b supplies power and a power controller 100 that is a power supply source from which the anode power supply 30b receives power are shown together. 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, a switch 32 included in the anode power supply 30 replaces the switch 39. And in the anode power supply 30b, a configuration is adopted in which the negative electrode terminal of the first-stage battery B-1 of the series battery BS and the cathode electrode Ec of the hole thruster 10 are always connected. Other configurations and components in the anode power supply 30b are the same as those of the anode power supply 30 in the first embodiment. Therefore, a repeated description of other configurations and components included in the anode power supply 30b is omitted.

[0065] Switch 39 is a switch for exclusively switching whether or not to connect the power controller 100 to both ends of the battery B. More specifically, when charging each battery B with the power supplied by the power controller 100, switch 39 connects the power controller 100 to both ends of each of the batteries B connected in parallel, and when operating the Hall thruster 10, when supplying the power stored by connecting each battery B in series to the anode 12, switch 39 disconnects each battery B from the power controller 100. That is, similar to switch 32 provided in the anode power supply 30 of the first embodiment, switch 39 operates as a function of insulating the power controller 100 and the operating Hall thruster 10. Similar to switch 32 provided in the anode power supply 30 of the first embodiment, switch 39 is, for example, a mechanical contact type switch. The switching of the connection destination of switch 39 is also controlled simultaneously with each of switches 31-1 to 31-5 by, for example, the battery drive unit BD, similar to switch 32 provided in the anode power supply 30 of the first embodiment. That is, when charging each battery B with the power supplied by the power controller 100, the battery drive unit BD controls switch 39 so that the power controller 100 is connected to both ends of each of the batteries B connected in parallel, and when outputting the power stored in the battery B to operate the Hall thruster 10, the battery drive unit BD controls switch 39 to disconnect the power controller 100 from the serially connected batteries B-1 to B-6. Thereby, also in the anode power supply 30b, similar to the anode power supply 30 of the first embodiment, it is possible to suppress the noise generated due to the discharge occurring between the anode 12 and the hollow cathode body 15a from leaking to the power controller 100 side and having an impact. As a result, also in the anode power supply 30b, similar to the anode power supply 30 of the first embodiment, without performing operations such as converting the DC power supplied by the power controller 100 into AC power like the anode power supply provided in the conventional Hall thruster system, it is possible to obtain the power supplied to the anode 12 as DC power, and with a simpler configuration than the conventional anode power supply, it is possible to insulate the power controller 100 and the operating Hall thruster 10.

[0066] Switch 39 is an example of the "second switch section".

[0067] The control of the anode power supply 30b in the battery drive unit BD and the operation of the anode power supply 30b can be easily considered from the operation of the anode power supply 30 of the first embodiment described with reference to FIG. 3, and thus a detailed description thereof will be omitted. Similar to the anode power supply 30 of the first embodiment described with reference to FIG. 4, the anode power supply 30b may 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 considered from the modified example of the anode power supply 30 of the first embodiment shown in FIG. 4, and thus a detailed description thereof will be omitted.

[0068] With such a configuration and operation (control of the battery drive unit BD), even the anode power supply 30b, similar to the anode power supply 30 of the first embodiment, connects the respective batteries B in parallel to charge the power supplied by the power controller 100 (the power of the system power supply), and connects the respective batteries B in series (assuming it is a series battery BS) to supply power to the anode 12. Thereby, even the anode power supply 30b can supply power to the anode 12 more efficiently, similar to the anode power supply 30 of the first embodiment, and a Hall thruster 10 with high power can be mounted on a small spacecraft where the power that can be supplied by the system power supply is not large, enhancing the superiority of the small spacecraft equipped with the power processing unit 20 to which the anode power supply 30b is applied.

[0069] FIG. 5 shows an example of the configuration when the switch 39 is a mechanical contact switch. However, the configuration of the switch 39 is not limited to the configuration shown in FIG. 5 as long as it can realize the respective functions described above. For example, the switch 39 may be a semiconductor switch.

[0070] As described above, the anode power source 30 (including the anode power sources 30a and 30b) of the embodiment is provided in the power processing unit 20 of the Hall thruster system 1 instead of the anode power source provided in the power processing unit in the conventional Hall thruster system. In the anode power source 30 of the embodiment, the batteries B included in the anode power source  30 are connected in parallel to charge the power supplied by the power controller 100, and the batteries B are connected in series to apply a high voltage to the anode 12. As a result, even in the Hall thruster system 1 including the power processing unit 20 to which the anode power source 30 of the embodiment is applied, when electrons of the propellant gas are emitted from the hollow cathode part 15 side to the channel part 11 side in the same manner as in the conventional Hall thruster system, a discharge occurs between the anode 12 and the hollow cathode body 15a. And, even in the Hall thruster system 1 including the power processing unit 20 to which the anode power source 30 of the embodiment is applied, in the same manner as in the conventional Hall thruster system, ions extracted by ionizing the propellant gas by the plasma generated by the discharge are accelerated by the electric field generated by the anode 12 and the hollow cathode body 15a and ejected from the channel part 11 into outer space. As a result, even in the Hall thruster system 1 including the power processing unit 20 to which the anode power source 30 of the embodiment is applied, a propulsive force can be applied to the spacecraft in the same manner as in the conventional Hall thruster system. Moreover, since the anode power source 30 of the embodiment supplies power from the battery B included in the anode power source 30 to the anode 12, it is possible to mount the high-power Hall thruster 10 on a small spacecraft without increasing the power of the battery such as the system power source and the power controller, which is required when adopting the intermittent operation method considered in the conventional Hall thruster system.

[0071] In the above-described embodiment, the case where the battery drive unit BD is provided in the anode power supply 30 has been described. However, the battery drive unit BD is not limited to the configuration provided in the anode power supply 30. For example, the battery drive unit BD may be configured to 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 drive unit BD may be made 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 the anode power supply 30 in which the battery drive unit BD is provided in the power processing unit 20 or the power controller 100 and the control of the battery drive unit BD are omitted.

[0072] In the above-described embodiment, the case where the anode power supply 30 includes six batteries B (batteries B-1 to B-6) has been described. However, the number of batteries B provided in the anode power supply 30 is not limited to six. For example, it may be determined based on the power supplied from the power controller 100 to the anode power supply 30 and the power supplied from the anode power supply 30 to the anode 12. Even when the number of batteries B provided in the anode power supply 30 is different, the configuration of the anode power supply 30 and the control of each switch by the battery drive unit BD may be made 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 the anode power supply 30 with a different number of batteries B provided and the control of the battery drive unit BD are omitted.

[0073] In the above-described embodiments, the configuration of each battery B, that is, the number and connection of the battery cells included in the battery B have not been particularly described. The number and connection of the battery cells included in each battery B may be determined, for example, based on the injection time of ions per cycle in the Hall thruster 10. Here, the injection time of ions per cycle in the Hall thruster 10 is also related to the charge capacity (electric capacity) of the battery cell. For this reason, the connection method of the battery cells in the battery B is not limited to series connection, and a connection method combining series connection and parallel connection may be used so as to increase the electric capacity of the battery B while keeping the voltage output from the battery B constant. For example, consider a case where each battery cell has a voltage value of 3.7 [V] and an electric capacity of 1 [Ah], and the battery B is composed of 20 battery cells. In this case, in the battery B, for example, two battery cell sets obtained by connecting 10 battery cells in series are connected in parallel (that is, each battery cell is connected in ten series and two parallel), whereby it can be configured as one battery B having a voltage value of 37 [V] and an electric capacity of 20 [Ah]. And when using eight battery Bs configured in this way as the anode power supply 30 having the configuration shown in FIG. 2, the anode power supply 30 can supply power with a maximum voltage value of 296 [V] and a current value of 160 [Ah] to the anode 12. Even 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 made 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 regarding the configuration of the anode power supply 30 and the control of the battery drive unit BD in this case is omitted.

[0074] In the above-described embodiment, the case where the anode power supply 30 is applied to the Hall thruster system 1 has been described as an example. However, the system of the electric propulsion device to which the anode power supply 30 is applied is not limited to the Hall thruster system 1, and any system of an electric propulsion device that ionizes and extracts a propellant gas by plasma (plasma discharge) generated by discharge and injects the ions into outer space can apply the anode power supply 30. In other words, for any system of an electric propulsion device that involves plasma discharge, the anode power supply 30 can be adopted as a power supply that supplies power to at least the component that causes plasma discharge. For example, the anode power supply 30 can be adopted as a power supply that supplies power to a component that discharges ions obtained by ionizing and extracting a propellant gas in an ion engine. 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 made 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 descriptions of the configuration of the anode power supply 30 and the control of the battery drive unit BD when the anode power supply 30 is adopted in the ion engine are omitted.

[0075] As described above, the embodiments for implementing the present invention have been described using the embodiments. However, the present invention is not limited to such embodiments, and various modifications and substitutions can be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0076] 1 ··· Hall thruster system 10 ··· Hall thruster 11 ··· Channel section 12 ··· Anode 12a ··· Gas supply pipe 13 ··· Wall section 14 ··· Electromagnet 14a ··· Internal electromagnet 14b ··· External electromagnet 15... Hollow cathode section 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... Battery 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 propulsion force of a space machine, comprising: a plurality of batteries; a plurality of first switch units provided corresponding to every two adjacent ones of the batteries, for switching the connection between the corresponding two batteries to series connection or parallel connection; a second switch unit for switching whether to connect a power supply source to each of the batteries; A power supply device comprising:

2. The second switch unit switches whether to connect a 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. The second switch unit: when the electric thruster does not generate the propulsion force, connects the 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 propulsion force, disconnects the path from the power supply source. The power supply device according to Claim 1.

4. A third switch unit is further provided, which is arranged between the 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, and controls the voltage rise time such 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 is further provided, which is arranged between the positive terminal of each of the batteries connected in parallel and the power supply source, turns off when the voltage corresponding to the power stored in each of the batteries reaches a predetermined voltage, and limits the current flowing from the power supply source to the positive terminal side of each of the batteries when in the on state. The power supply device according to any one of Claims 1 to 4. ​ ​ The power supply device according to claim 4.

6. A voltage conversion unit that is arranged in front of or behind the third switch unit and boosts or steps down the voltage between the first positive terminal and the first power supply destination. further comprising The power supply device according to claim 5.

7. A fifth switch unit for controlling the connection between a second positive terminal that is the positive terminal of any one of the serially connected batteries and a second power supply destination that is a component of the electric thruster. further comprising The power supply device according to claim 6.

8. The electric thruster is an electric thruster that generates the thrust by ejecting ions extracted by ionizing a predetermined gas by plasma generated by a discharge caused by applying a high voltage. The power supply device according to claim 7.

9. The electric thruster is a Hall thruster. 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.

10. The power supply source is a power controller that supplies power from a system power supply 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 arranged between the first positive terminal and the anode electrode of the anode The first negative terminal is connected to the cathode electrode of the hollow cathode of the Hall thruster. The power supply device according to claim 9.

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

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.

13. The fourth 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 12.

14. The fifth 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 13.

15. The second power supply destination is a component other than the anode of the Hall thruster. The fifth switch section is disposed between the second positive electrode terminal and an electrode of a corresponding component other than the anode. The power supply device according to claim 14. **Claim 16** The electrode of the component other than the anode is a keeper electrode of a hollow cathode section included in the hall thruster. The power supply device according to claim 15. **Claim 17** The electrode of the component other than the anode is a heater electrode of a heater of a hollow cathode section included in the hall thruster. The power supply device according to claim 15. **Claim 18** The electrode of the component other than the anode is a coil electrode of a coil constituting an electromagnet included in the hall thruster. The power supply device according to claim 15. **Claim 19** 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. The power supply device according to claim 15.

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