Electric propulsion method for ships

Abstract

To preferably supply a storage cell included in an electric propulsion ship with direct-current power converted from alternating-current power from an alternating-current power supply irrespective of a location of the alternating-current power supply in the electric propulsion ship.SOLUTION: An electric propulsion system for a ship includes: one or more propulsion electric motors for propelling a ship; one or more secondary cells for supplying electrical power to the propulsion electric motors; and one or more power conversion units for charging the secondary cells with direct-current power. The secondary cells are a major power supply source for the propulsion electric motors.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electric propulsion system for a ship, a ship, and an electric propulsion method for a ship. [Background technology]

[0002] 2. Description of the Related Art Conventionally, electric propulsion ships are known that convert AC power from an onshore power source into DC power, and then supply the DC power to a storage battery provided on the electric propulsion ship (see, for example, Patent Documents 1 to 3). Patent Document 1: JP 2016-43715 A Patent Document 2: Patent No. 5164048 Patent Document 3: Patent No. 5584809 Summary of the Invention [Problem to be solved by the invention]

[0003] In an electric propulsion ship, regardless of the location of an AC power source, it is preferable to be able to supply DC power obtained by converting AC power from the AC power source to a storage battery provided on the electric propulsion ship. [Means for solving the problem]

[0004] In a first aspect of the present invention, there is provided an electric propulsion system for a marine vessel. The electric propulsion system for a marine vessel includes one or more propulsion motors for propelling the marine vessel, one or more secondary batteries for supplying power to the propulsion motors, and one or more power converters for charging the secondary batteries with DC power. The secondary batteries are a main power source for the propulsion motors.

[0005] The one or more power conversion units may convert AC power supplied from an AC power source into DC power, and may charge the secondary battery with the DC power.

[0006] The AC power source may be a portable power supply facility.

[0007] The AC power source may be a power facility provided on shore.

[0008] The ship may have a vehicle mounting section on which the vehicle is mounted. The portable power supply facility may be a power supply vehicle. The power supply vehicle may be mounted on the vehicle mounting section. The AC power supply may be mounted on the power supply vehicle.

[0009] The secondary battery may be the sole source of power for the propulsion motor.

[0010] The marine vessel electric propulsion system may further include a switch, which may control an electrical connection between the one secondary battery and the other propulsion motor, and may control an electrical connection between the other secondary battery and the one propulsion motor. When the secondary battery is to be charged, the one power conversion unit and the other power conversion unit may charge the one secondary battery by turning on the switch, and the one power conversion unit and the other power conversion unit may charge the other secondary battery. When the secondary battery is to be discharged, the one secondary battery may supply power to the one propulsion motor by turning off the switch, and may not supply power to the other propulsion motor. When the secondary battery is to be discharged, the other secondary battery may supply power to the other propulsion motor by turning off the switch, and may not supply power to the one propulsion motor.

[0011] The ship may perform a series of tests consuming more power than would be consumed if the total capacity of one or more secondary batteries were consumed.

[0012] The power conversion unit may charge the secondary battery when the vessel is conducting a test.

[0013] The power conversion unit may stop charging the secondary battery when the vessel is conducting a test.

[0014] According to a second aspect of the present invention, there is provided a marine vessel, the marine vessel may be equipped with an electric marine propulsion system.

[0015] In a third aspect of the present invention, there is provided a marine vessel electric propulsion method. The marine vessel electric propulsion method includes a step of converting AC power supplied from an AC power source into DC power by a power conversion unit provided on the marine vessel, and a step of charging a secondary battery provided on the marine vessel with the DC power. In the marine vessel electric propulsion method, the secondary battery supplies power to a propulsion motor that propels the marine vessel. In the marine vessel electric propulsion method, the secondary battery is a main power supply source for the propulsion motor.

[0016] In the electric propulsion method for a marine vessel, the secondary battery may be the only power source for the propulsion motor.

[0017] The above summary of the invention does not list all of the necessary features of the present invention. Also, subcombinations of these features may also be inventions. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 illustrates an example of a vessel 200 according to an embodiment of the present invention. [Diagram 2] 1 is a system configuration diagram showing an example of a marine electric propulsion system 100 according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram showing another example of a vessel 200 according to an embodiment of the present invention. [Figure 4] FIG. 2 is a system configuration diagram showing another example of a marine electric propulsion system 100 according to an embodiment of the present invention. [Diagram 5] 2 is a flowchart illustrating an example of a marine electric propulsion method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0020] 1 is a diagram showing an example of a ship 200 according to an embodiment of the present invention. The ship 200 includes a hull 210, one or more propellers 220, and a marine electric propulsion system 100. The propellers 220 are provided in the hull 210. When the ship 200 is sailing, the propellers 220 are disposed in the ocean. The propellers 220 are, for example, propellers.

[0021] The ship 200 of this example is equipped with two screws 220. In Fig. 1, the traveling direction of the ship 200 is indicated by a thick arrow. When the ship 200 is a so-called double-ended ship equipped with screws 220 at the front and rear of the hull 210, the screws 220-1 and 220-2 are the screws 220 arranged at the front and rear of the ship 200, respectively, based on the traveling direction of the ship 200. When the ship 200 is equipped with one screw 220, the screw 220 may be arranged at the rear of the ship 200 based on the traveling direction of the ship 200.

[0022] The marine vessel electric propulsion system 100 includes one or more propulsion motors 10. The number of propellers 220 and the number of propulsion motors 10 may be equal to or different from each other. One propulsion motor 10 may rotate one propeller 220, or multiple propulsion motors 10 may rotate one propeller 220. When the marine vessel 200 includes multiple propellers 220 and the marine vessel electric propulsion system 100 includes multiple propulsion motors 10, the number of propellers 220 and the number of propulsion motors 10 may be equal to or different from each other. When the number of propellers 220 and the number of propulsion motors 10 are equal to each other, a propulsion motor 10 may be provided for each propeller 220. The propulsion motor 10 rotates the propeller 220. The propulsion motor 10 propels the marine vessel 200 by rotating the propeller 220.

[0023] The marine vessel electric propulsion system 100 of this example includes two propulsion motors 10. In this example, the propulsion motor 10-1 and the propulsion motor 10-2 rotate the propellers 220-1 and 220-2, respectively.

[0024] Fig. 2 is a system configuration diagram showing an example of a marine electric propulsion system 100 according to an embodiment of the present invention. In Fig. 2, the range of the marine electric propulsion system 100 is indicated by a rough dashed line.

[0025] The marine vessel electric propulsion system 100 includes one or more propulsion motors 10, one or more secondary batteries 30, and one or more power conversion units 24. The propulsion motor 10 propels the marine vessel 200. The secondary battery 30 supplies power to the propulsion motor 10. The power conversion unit 24 charges the secondary battery 30 with DC power. The power conversion unit 24 may charge the secondary battery 30 with a DC power source. In this example, the power conversion unit 24 converts AC power supplied from an AC power source 40 into DC power. In this example, the power conversion unit 24 charges the secondary battery 30 with the DC power. Note that one secondary battery 30 may include multiple battery cells. The multiple battery cells may be connected in series or in parallel.

[0026] The marine vessel electric propulsion system 100 may further include a transformer 16. The power conversion unit 24 may be supplied with AC power that has been transformed by the transformer 16 and is intended for the secondary battery 30.

[0027] The marine vessel electric propulsion system 100 of this example includes two propulsion motors 10, two secondary batteries 30, and two power conversion units 20. The secondary batteries 30-1 and 30-2 supply power to the propulsion motor 10-1. The secondary batteries 30-1 and 30-2 supply power to the propulsion motor 10-2. The power conversion unit 20-1 converts DC power supplied from the secondary batteries 30-1 and 30-2 into AC power. The power conversion unit 20-1 supplies the AC power to the propulsion motor 10-1. The power conversion unit 20-2 converts DC power from the secondary batteries 30-1 and 30-2 into AC power. The power conversion unit 20-2 supplies the AC power to the propulsion motor 10-2.

[0028] The secondary battery 30 is the main power supply source for the propulsion motor 10. The secondary battery 30 being the main power supply source for the propulsion motor 10 may refer to a state in which the secondary battery 30 supplies more than 50% and less than 100% of the power supplied to the propulsion motor 10, may refer to a state in which the secondary battery 30 supplies 70% or more and less than 100% of the power supplied to the propulsion motor 10, or may refer to a state in which the secondary battery 30 supplies 90% or more and less than 100% of the power supplied to the propulsion motor 10. The secondary battery 30 may be the only power supply source for the propulsion motor 10. In other words, 100% of the power supplied to the propulsion motor 10 may be supplied from the secondary battery 30.

[0029] The marine vessel electric propulsion system 100 may further include a power conversion unit 22, a transformer 14, and an onboard load 12. The power conversion unit 22 converts DC power supplied from the secondary battery 30 into AC power. The power conversion unit 22 supplies the AC power to the onboard load 12. The onboard load 12 may be supplied with AC power that has been transformed by the transformer 14 for the onboard load 12. The onboard load 12 is, for example, air conditioning equipment or the like provided in the hull 210. The marine vessel electric propulsion system 100 may include a plurality of onboard loads 12.

[0030] In this example, the boat 200 includes the boat electric propulsion system 100, and the boat electric propulsion system 100 includes a power conversion unit 24. Therefore, in the boat 200 of this example, the secondary battery 30 charged by the AC power source 40 can supply power to the propulsion motor 10.

[0031] The AC power source 40 may be a portable power source facility. The portable power source facility refers to a power source facility that can be freely carried into and removed from the hull 210. In other words, the portable power source facility is not permanently installed in the hull 210.

[0032] The amount of power that the portable power supply equipment can supply is defined as the amount of power Pc. The total capacity of the secondary batteries 30 included in the marine vessel electric propulsion system 100 is defined as the amount of power Ps. The amount of power Ps is the total amount of power that can be accommodated by the secondary batteries 30. When the marine vessel electric propulsion system 100 includes multiple secondary batteries 30, the amount of power Ps is the sum of the capacities of the multiple secondary batteries 30.

[0033] When the AC power source 40 is a portable power supply equipment, the power amount Pc may be greater than the power amount Ps. When the power amount Pc is greater than the power amount Ps, the portable power supply equipment can charge the secondary battery 30 to a fully charged state. The power amount Pc may be more than twice the power amount Ps, more than five times the power amount Ps, or more than ten times the power amount Ps.

[0034] The AC power source 40 may be a power supply facility provided on land. The AC power source 40 may be a power supply facility provided in a port where the ship 200 is anchored. When the AC power source 40 is a power supply facility provided on land, the ship 200 may charge the secondary battery 30 using the power supply facility provided on land. The ship 200 can navigate the ocean by supplying power from the secondary battery 30 to the propulsion motor 10.

[0035] The ship 200 may perform a test in the ocean by supplying power from the secondary battery 30 to the propulsion motor 10. The test performed by the ship 200 refers to a test to confirm whether the ship 200 has various performance characteristics for practical use before the ship 200 is put to practical use. The test is performed in the ocean. The test may be at least one of a speed test, a forward / reverse test, a turning test, a stationary coasting test, a low-speed steering effect test, and a continuing test. The continuing test may be performed for one hour or more. The test performed by the ship 200 may include an investigation of the degree of decrease in the amount of stored electricity in the secondary battery 30 accompanying the execution of the test.

[0036] FIG. 3 is a diagram showing another example of a ship 200 according to an embodiment of the present invention. The ship 200 of this example differs from the ship 200 shown in FIG. 1 in that it has a vehicle mounting section 230. In addition, in this example, the portable power supply equipment is a power supply vehicle 50. A power supply vehicle is an automobile equipped with a generator. In this example, an AC power supply 40 is mounted on the power supply vehicle 50. In this example, the power supply vehicle 50 is mounted on the vehicle mounting section 230. The power supply vehicle 50 may be mounted on the ship 200 while it is anchored in a port.

[0037] The vessel 200 may be a so-called ferry designed to carry four-wheeled automobiles, two-wheeled vehicles, etc. The vehicle loading section 230 may be at least a part of the vehicle deck of the ferry.

[0038] The portable power supply equipment may be a container. When the portable power supply equipment is a container, the AC power supply 40 may be mounted on the container. The container may be carried into the hull 210 from the port by a predetermined transportation means while the ship 200 is anchored at the port.

[0039] In this example, a power supply vehicle 50 is mounted on the vehicle mounting unit 230 of the ship 200, and the secondary battery 30 is charged by an AC power source 40 mounted on the power supply vehicle 50. The ship electric propulsion system 100 converts AC power supplied from the AC power source 40 into DC power by the power conversion unit 24. Therefore, the ship electric propulsion system 100 can supply power from the secondary battery 30 to the propulsion motor 10 while charging the secondary battery 30 with the DC power. Therefore, when the ship 200 performs a test at sea, the ship 200 can perform the test for a longer period of time than if the power supply vehicle 50 is not mounted on the ship 200.

[0040] The ship 200 may continuously perform tests that consume more power than the total capacity of one or more secondary batteries 30. The ship 200 continuously performs tests means that the ship 200 performs a set of predetermined tests at sea without going through a step of returning to port once to charge the secondary battery 30. The ship 200 continuously performs tests does not mean that the ship 200 performs tests continuously at sea without stopping the supply of power from the secondary battery 30 to the propulsion motor 10 even once. In other words, the ship 200 may stop the supply of power from the secondary battery 30 to the propulsion motor 10 after performing one test at sea and before performing another test.

[0041] In this example, the marine vessel electric propulsion system 100 can supply power from the secondary battery 30 to the propulsion motor 10 while charging the secondary battery 30 with DC power converted from AC power supplied from an AC power source 40 mounted on a power source vehicle 50. This makes it easier for the marine vessel 200 to continuously perform tests that consume more power than would be consumed if the total capacity of the secondary batteries 30 were consumed.

[0042] The power conversion unit 24 may charge the secondary battery 30 when the boat 200 is performing a test. In other words, the power conversion unit 24 may charge the secondary battery 30 in parallel during a period when the boat 200 is performing a test. This allows the boat electric propulsion system 100 to increase the amount of stored electricity in the secondary battery 30 after the test is performed, compared to a case in which the power conversion unit 24 does not charge the secondary battery 30 in parallel. This makes it easier for the boat 200 to perform multiple types of tests consecutively.

[0043] The power conversion unit 24 may stop charging the secondary battery 30 when the ship 200 is performing a test. In other words, the power conversion unit 24 may not charge the secondary battery 30 in parallel during a period when the ship 200 is performing a test. This allows the ship electric propulsion system 100 to stabilize the supply of power from the secondary battery 30 to the propulsion motor 10 during a period when the ship 200 is performing the test. The power conversion unit 24 may charge the secondary battery 30 after the ship 200 has performed a test and before performing another test.

[0044] As described above, there are multiple types of tests that the ship 200 performs. When the ship 200 performs multiple tests at sea, the power supplied from the secondary battery 30 is more likely to decrease than when one type of test is performed. For this reason, the power of the secondary battery 30 is likely to reach a charged amount that is not sufficient to drive the propulsion motor 10.

[0045] In this example, the power supply vehicle 50 is mounted on the vehicle mounting unit 230 of the ship 200, and the secondary battery 30 is charged by the AC power source 40 mounted on the power supply vehicle 50, so that, as described above, the ship 200 can easily perform testing for a longer period of time than if the power supply vehicle 50 was not mounted. Furthermore, since the marine vessel electric propulsion system 100 of this example is equipped with the power conversion unit 24, the ship 200 can perform testing simply by mounting the power supply vehicle 50 on the ship 200. This simplifies the preparation of the ship 200 to perform testing. This reduces the time required for the ship 200 to prepare to perform testing.

[0046] Fig. 4 is a system configuration diagram showing another example of a marine vessel electric propulsion system 100 according to an embodiment of the present invention. In Fig. 4, the range of the marine vessel electric propulsion system 100 is indicated by a rough dashed line.

[0047] The marine vessel electric propulsion system 100 includes one or more propulsion motors 10, one or more first secondary batteries 32, one or more other secondary batteries 34, and one or more power conversion units 26. The one secondary battery 32 supplies power to the propulsion motor 10. The other secondary batteries 34 supply power to the propulsion motor 10. The power conversion unit 26 converts AC power from an AC power source 40 into DC power. The power conversion unit 26 charges at least one of the one secondary battery 32 and the other secondary batteries 34 with the DC power.

[0048] The marine vessel electric propulsion system 100 of this example includes two propulsion motors 10, two first secondary batteries 32, two other secondary batteries 34, and two power conversion units 20. In this example, one of the two propulsion motors 10 is referred to as the first propulsion motor 10-1 and the other of the two propulsion motors 10-2, respectively.

[0049] The marine electric propulsion system 100 may further include a transformer 18 and a switch 60. The power conversion unit 26 may be supplied with AC power that has been transformed by the transformer 18 for the one secondary battery 32 and the other secondary battery 34.

[0050] The marine vessel electric propulsion system 100 of this example includes two power conversion units 26. In this example, one of the two power conversion units 26 is referred to as one power conversion unit 26-1 and the other power conversion unit 26-2, respectively. The switch 60 controls the electrical connection between the one secondary battery 32 and the other propulsion motor 10-2, and also controls the electrical connection between the other secondary battery 34 and the one propulsion motor 10-1.

[0051] When charging the one secondary battery 32 and the other secondary battery 34, the one power conversion unit 26-1 and the other power conversion unit 26-2 may charge the one secondary battery 32 and may charge the other secondary battery 34 by turning on the switch 60. When charging the one secondary battery 32, the one power conversion unit 26-1 may charge the one secondary battery 32 by turning off the switch 60, and the other power conversion unit 26-2 may not charge the one secondary battery 32. When charging the other secondary battery 34, the other power conversion unit 26-2 may charge the other secondary battery 34 by turning off the switch 60, and the one power conversion unit 26-1 may not charge the other secondary battery 34.

[0052] When the one secondary battery 32 and the other secondary battery 34 are discharging, the one secondary battery 32 may supply power to the one propulsion motor 10-1 and may not supply power to the other propulsion motor 10-2 by turning off the switch 60. When the one secondary battery 32 and the other secondary battery 34 are discharging, the other secondary battery 34 may supply power to the other propulsion motor 10-2 and may not supply power to the one propulsion motor 10-1 by turning off the switch 60. In this case, the supply of power to the one propulsion motor 10-1 due to the discharge of the one secondary battery 32 and the supply of power to the other propulsion motor 10-2 due to the discharge of the other secondary battery 34 may be performed at the same timing or at different timings.

[0053] The marine vessel electric propulsion system 100 may further include a plurality of power conversion units 22, a plurality of transformers 14, and a plurality of onboard loads 12. The marine vessel electric propulsion system 100 of this example includes two power conversion units 22 (power conversion unit 22-1 and power conversion unit 22-2), two transformers 14 (transformer 14-1 and transformer 14-2), and two onboard loads 12 (onboard load 12-1 and onboard load 12-2).

[0054] When the switch 60 is off, the power conversion unit 22-1 converts the DC power of one of the secondary batteries 32 into AC power. The power conversion unit 22-1 supplies the AC power to the onboard loads 12-1. The onboard loads 12-1 may be supplied with AC power that has been transformed by the transformer 14-1 for use by the onboard loads 12-1.

[0055] When the switch 60 is off, the power conversion unit 22-2 converts the DC power of the other secondary battery 34 into AC power. The power conversion unit 22-2 supplies the AC power to the onboard load 12-2. The onboard load 12-2 may be supplied with AC power that has been transformed by the transformer 14-2 for the onboard load 12-2.

[0056] The marine vessel electric propulsion system 100 of this example further includes a switch 60 that controls the electrical connection between the one secondary battery 32 and the other propulsion motor 10-2 and also controls the electrical connection between the other secondary battery 34 and the one propulsion motor 10-1. Therefore, when the one secondary battery 32 and the other secondary battery 34 are discharging, the marine vessel electric propulsion system 100 can independently control the supply of power from the one secondary battery 32 to the one propulsion motor 10-1 and the onboard load 12-1 and the supply of power from the other secondary battery 34 to the other propulsion motor 10-2 and the onboard load 12-2 by turning off the switch 60.

[0057] Fig. 5 is a flowchart showing an example of a marine vessel electric propulsion method according to an embodiment of the present invention. Hereinafter, the marine vessel electric propulsion method according to an embodiment of the present invention will be described using the marine vessel electric propulsion system 100 shown in Fig. 2 as an example.

[0058] The AC power supplied from the AC power supply 40 is defined as AC power Pa. The DC power obtained by converting the AC power Pa by the power conversion unit 24 is defined as DC power Pd. The marine vessel electric propulsion method includes step S100 in which the power conversion unit 24 provided in the marine vessel 200 converts the AC power Pa into DC power Pd, and step S110 in which the secondary battery 30 provided in the marine vessel 200 is charged with the DC power Pd.

[0059] In the marine vessel electric propulsion method of this example, the secondary battery 30 supplies electric power to the propulsion motor 10 that propels the marine vessel 200. In the marine vessel electric propulsion method of this example, the secondary battery 30 is the main power supply source for the propulsion motor 10. The secondary battery 30 may be the only power supply source for the propulsion motor 10.

[0060] The marine vessel electric propulsion method of this example includes a step S100 in which the power conversion unit 24 provided on the marine vessel 200 converts AC power Pa into DC power Pd. Therefore, in the marine vessel electric propulsion method of this example, even when an AC power source 40 is installed on the marine vessel 200, the power conversion unit 24 can charge the secondary battery 30 provided on the marine vessel 200 with the DC power Pd.

[0061] The marine vessel electric propulsion method may further include, prior to step S100, a step of mounting a power supply car 50 equipped with an AC power source 40 onto the marine vessel 200. In this step, the power supply car 50 may be mounted on the vehicle mounting unit 230. This step may be performed while the marine vessel 200 is anchored at a port. This step may also be a step of mounting a container equipped with an AC power source 40 onto the marine vessel 200.

[0062] The marine vessel electric propulsion method may further include, after step S110, a step of causing the marine vessel 200 to perform a test by supplying power from the secondary battery 30 to the propulsion motor 10. This step may be performed in parallel with step S110. In other words, the marine vessel 200 may perform the test while charging the secondary battery 30 with DC power Pd.

[0063] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the description of the claims that such modifications and improvements can also be included in the technical scope of the present invention.

[0064] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and may be realized in any order unless the output of a previous process is used in a later process. Even if the operational flow in the claims, specifications, and drawings is explained using "first," "next," etc. for convenience, it does not mean that it is essential to perform the process in this order. [Item 1] One or more electric propulsion motors for propelling the vessel; one or more secondary batteries for supplying power to the propulsion motor; one or more power conversion units that charge the secondary battery with DC power; Equipped with The secondary battery is a main power source for the propulsion motor. Electric propulsion systems for ships. [Item 2] 2. The marine electric propulsion system according to claim 1, wherein the one or more power conversion units convert AC power supplied from an AC power source into DC power and charge the secondary battery with the DC power. [Item 3] 3. The marine electric propulsion system according to claim 2, wherein the AC power source is a portable power supply facility. [Item 4] 3. The marine electric propulsion system according to claim 2, wherein the AC power source is a power supply facility provided on land. [Item 5] The ship has a vehicle mounting section on which a vehicle is mounted, The portable power supply equipment is a power supply vehicle, The power supply vehicle is mounted on the vehicle mounting section, The AC power source is mounted on the power supply vehicle. 4. An electric propulsion system for a marine vessel according to item 3. [Item 6] 6. The marine electric propulsion system according to any one of claims 1 to 5, wherein the secondary battery is the sole power source for the propulsion motor. [Item 7] a switch that controls an electrical connection between one of the secondary batteries and another of the propulsion motors, and also controls an electrical connection between the other of the secondary batteries and one of the propulsion motors; When the secondary battery is to be charged, the switch is turned on. one of the power conversion units and the other of the power conversion units charge one of the secondary batteries; one of the power conversion units and the other of the power conversion units charge the other of the secondary batteries; When the secondary battery is discharged, the switch is turned off. one of the secondary batteries supplies power to one of the propulsion motors and does not supply power to the other of the propulsion motors; The other secondary battery supplies power to the other propulsion motor and does not supply power to the one propulsion motor. 7. An electric propulsion system for a marine vessel according to any one of items 1 to 6. [Item 8] 8. A marine electric propulsion system according to any one of items 1 to 7, wherein the marine vessel continuously conducts tests in which the marine vessel consumes more power than the total capacity of the one or more secondary batteries. [Item 9] 9. The marine vessel electric propulsion system according to claim 8, wherein the power conversion unit charges the secondary battery when the marine vessel is conducting the test. [Item 10] 9. The marine vessel electric propulsion system according to claim 8, wherein the power conversion unit stops charging the secondary battery when the marine vessel is conducting the test. [Item 11] A ship equipped with the marine electric propulsion system according to any one of items 1 to 10. [Item 12] A power conversion unit provided in the vessel converts AC power supplied from the AC power source into DC power; charging a secondary battery provided on the marine vessel with the DC power; Equipped with The secondary battery supplies power to a propulsion motor that propels the marine vessel, The secondary battery is a main power source for the propulsion motor. Electric propulsion method for ships. [Item 13] Item 13. The marine electric propulsion method according to item 12, wherein the secondary battery is the sole power source for the propulsion motor. [Explanation of symbols]

[0065] 10 propulsion motor, 12 onboard load, 14 transformer, 16 transformer, 18 transformer, 20 power conversion section, 22 power conversion section, 24 power conversion section, 26 power conversion section, 30 secondary battery, 32 secondary battery, 34 secondary battery, 40 AC power source, 50 power supply vehicle, 60 switch, 100 marine electric propulsion system, 200 ship, 210 hull, 220 screw, 230 vehicle mounting section

Claims

1. One or more electric propulsion motors for propelling the vessel; one or more secondary batteries for supplying power to the propulsion motor; one or more power conversion units that charge the secondary battery with DC power; a switch that controls an electrical connection between one of the secondary batteries and another of the propulsion motors, and also controls an electrical connection between the other of the secondary batteries and one of the propulsion motors; A marine electric propulsion method for a marine electric propulsion system comprising: a charging step in which the one of the power conversion units and the other of the power conversion units charge the one of the secondary batteries by turning on the switch, and the one of the power conversion units and the other of the power conversion units charge the other of the secondary batteries; a first power supply step of turning off the switch when the one secondary battery and the other secondary battery are discharging, so that the one secondary battery supplies power to the one propulsion motor and does not supply power to the other propulsion motors; A marine electric propulsion method comprising:

2. 2. The marine electric propulsion method according to claim 1, further comprising a second power supply step of, when the one secondary battery and the other secondary battery are discharging, turning off the switch so that the other secondary battery supplies power to the other propulsion motor and does not supply power to the one propulsion motor.

Images