JP7526219B2 - Battery-powered electric propulsion ship system - Google Patents

Description

The present invention relates to a battery-equipped electric propulsion ship system that includes a main engine (propulsion motor), a storage battery, a generator motor, and propulsion means for propelling the ship's hull, and that controls the operation of the generator motor most efficiently depending on the remaining charge of the storage battery and the operating conditions.

Ships are highly energy efficient and have low carbon dioxide emissions compared to other forms of transportation. For this reason, although a modal shift to domestic shipping for domestic cargo transport is being encouraged on a national scale, the movement is still slow. To promote the modal shift, there is a widespread demand for highly economical ships that can reduce environmental impact and transportation costs.

In addition, the recent demographic change, which has resulted in a declining birthrate and an aging population, has caused a serious shortage of domestic marine personnel. As one solution to this problem, it is expected that ships with highly energy-efficient operation capabilities that use innovative and new technologies will emerge in the domestic shipping sector.

In the past, ship management using batteries involved using the generator as the main power supply device, with storage batteries being used as a demand measure for the generator at maximum load during regular navigation (see Patent Documents 1 and 2). However, the use of storage batteries as the main power supply equipment in all situations, such as regular navigation and slow navigation, had not been adopted for coastal ships. This was because, when an electric propulsion system was installed on a ship, it was difficult to efficiently operate the generator according to the navigation situation and to appropriately control the amount of electricity stored in the storage batteries.

As mentioned above, ship systems equipped with storage batteries and propelled solely by electricity are not yet a reality, but recently it has been proposed to control the output of the propulsion motors in such ship systems based on the amount of electricity stored in the storage batteries.

For example, Patent Document 3 proposes that in an electric propulsion system that propels a ship using electricity stored in a storage battery, the output of the propulsion motor is controlled based on the storage battery's state of charge to prevent the storage battery from discharging to a point where the ship cannot be propelled.

However, in the system of Patent Document 3, the output of the propulsion motor is controlled based on the charge state of the storage battery, so the output is controlled to be reduced even during normal navigation, and in the current situation, in ships that use propulsion motors as their main engines, the propulsion and power supply of the ship cannot be efficiently controlled in accordance with various operating conditions from the perspective of energy conservation.

JP 2013-209018 A JP 2015-3658 A JP 2021-54353 A

The present invention was devised in light of the current state of the prior art, and its purpose is to provide a battery-mounted electric propulsion ship system that includes a main engine (propulsion motor), a storage battery, a generator motor, and propulsion means for propelling the ship's hull, and that is highly energy-efficient and can control the operation of the generator motor and the supply of electricity most efficiently depending on the remaining charge of the battery and the operating conditions.

The inventors conducted extensive research to achieve this objective, and discovered that when the remaining charge in the storage battery reaches a specific capacity, the generator motor continues to generate electricity at a constant load until the remaining charge in the storage battery increases to almost full, thereby supplying power to the storage battery, the main engine, and the onboard loads. However, after the remaining charge in the storage battery reaches almost full, the generator motor is stopped until the remaining charge in the storage battery reaches a specific capacity, and the storage battery supplies power to the main engine and the onboard loads. This allows the generator motor to operate for a long period of time at its most efficient level, thereby achieving high energy savings and reducing equipment breakdowns and repairs, and thus leading to the invention.

That is, the present invention has been completed based on the above findings, and has the following configurations (1) to ( 5 ).
(1) A battery-equipped electric propulsion ship system including a main engine which is a propulsion motor, a storage battery, a generator prime mover, and a propulsion means for propelling a hull,
a main engine configured to provide propulsive power to the propulsion means;
the battery is configured to power the main engine and/or the onboard loads;
the generator prime mover is configured to generate electricity to power the main engine and/or the battery and/or the onboard loads;
(i) when the remaining charge of the storage battery becomes equal to or less than capacity X selected from 0 to 15% of the rated capacity, the generator-motor generates electricity to supply power to the storage battery and optionally supplies power to the main engine and/or onboard loads until the remaining charge of the storage battery becomes capacity Y selected from 90 to 100% of the rated capacity, (ii) after the remaining charge of the storage battery reaches capacity Y, the generator-motor is stopped and the storage battery supplies power to the main engine and/or onboard loads again until the remaining charge of the storage battery becomes equal to or less than capacity X, and thereafter the operations of (i) and (ii) are repeated ;
At least two electric generating engines are installed on board the ship, of which the first electric generating engine is used preferentially to supply power to the main engine and/or the battery and/or the onboard loads, and the second electric generating engine is used as an alternative source of power during failure and/or maintenance of the first electric generating engine, or as a source of assist power for the main engine during high-speed voyage operating at 80% or more of the maximum output of the main engine.
A battery-equipped electric propulsion ship system comprising:
(2) A battery-equipped electric propulsion ship system as described in (1), characterized in that the power generation of the power generating motor in the case of (i) is performed at a constant load.
( 3 ) A battery-equipped electric propulsion ship system as described in (1) or (2), characterized in that during normal navigation when the ship is operated at 50% or more of the maximum output of the main engine, (i) when the remaining charge of the storage battery falls below capacity X selected from 0 to 15% of the rated capacity, the generator-driven motor generates electricity to supply power to the storage battery and also to the main engine and onboard loads until the remaining charge of the storage battery reaches capacity Y selected from 90 to 100% of the rated capacity, and (ii) after the remaining charge of the storage battery reaches capacity Y, the generator-driven motor is stopped and the storage battery supplies power to the main engine and onboard loads again until the remaining charge of the storage battery falls below capacity X, and thereafter the operations of (i) and (ii) are repeated.
( 4 ) A battery-equipped electric propulsion ship system according to any one of (1) to (3), characterized in that, during low-speed navigation of 10 knots or less, the generator prime mover is stopped and the battery can be controlled to supply power to the main engine and onboard loads unless the remaining charge of the battery falls below a capacity X selected from 5 to 15 % of the rated capacity.
( 5 ) A battery-equipped electric propulsion ship system according to any one of (1) to ( 4 ), characterized in that it is used on an inland ship having a gross tonnage of 100 tons or more and less than 5,000 tons.

Since the ship system of the present invention can generate electricity while operating in such a way as to reduce load fluctuations in the generator motor, the following various effects can be expected.
(i) Since combustion can be performed in the part with the best fuel consumption rate, the energy saving effect is extremely high.
(ii) Causes of incomplete combustion and knocking in the generator engine are eliminated, reducing the risk of engine failure.
(iii) Since combustion occurs at the best combustion point in the generator engine, repair costs for pistons, liners, lubricants, etc. are reduced.
In addition, by using it in combination with a storage battery, the following effects can be expected.
(iv) The operating time of the generator engine will be reduced, which is expected to reduce the working hours of crew members.
(v) As a result of the above, repair costs are reduced.
(vi) As a result of the above, the operating time of auxiliary equipment (pumps, coolers, purifiers, etc.) required for operating the generator engine will be reduced, leading to a reduction in crew working hours and lower repair costs.
(vii) As a result of the above, the operating time of the equipment required to operate the generator, cooling equipment, fuel supply equipment, heating equipment, ventilation equipment, etc. will be reduced, which is expected to have the effects of reducing energy consumption, reducing repair costs, and shortening the working hours of crew members.
Furthermore, this is the first time that a ship uses an electric propulsion motor rather than an internal combustion engine as its main propulsion engine, and the electrification of ships will lead to various initiatives (such as CASE), just like cars.

FIG. 1 is a schematic diagram of a basic configuration of a battery-mounted electric propulsion ship system according to the present invention. FIG. 2 is a schematic diagram showing the control of the battery-mounted electric propulsion marine system of the present invention when the remaining charge of the storage battery is low. FIG. 3 is a schematic diagram showing the control of the battery-mounted electric propulsion marine system of the present invention when the remaining charge of the storage battery is sufficient. FIG. 4 is a schematic diagram showing the control of the battery-mounted electric propulsion ship system of the present invention during normal sailing. FIG. 5 is a schematic diagram showing the control of the battery-mounted electric propulsion ship system of the present invention during low-speed sailing. FIG. 6 is a schematic diagram showing the control of the battery-equipped electric propulsion ship system of the present invention when the ship is at anchor.

The battery-equipped electric propulsion ship system of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.

The ship system of the present invention can be applied to various ships regardless of the size or type of the ship, but from the perspective of practical feasibility, it is preferable to target domestic ships (particularly domestic cargo ships) with a gross tonnage of 100T or more, and particularly with a gross tonnage of 100T or more but less than 5000T.

The output of the main engine for the required ship speed during the operation of a coastal ship is greatly affected by weather and sea conditions, and generally varies greatly depending on the situation. In addition, the required ship speed also varies depending on the operation plan, so in many cases the main engine is selected with consideration given to use at the maximum ship speed and maximum output in the operation plan. However, there are a few cases where a small main engine is installed in the event of adverse weather and sea conditions, with the intention of abandoning the voyage that meets the required ship speed and evacuating. In any case, the required output changes easily depending on the operation situation, and so the ship is characterized by relatively large fluctuations in fuel consumption.

The ship system of the present invention is intended for a battery-equipped electric propulsion ship that uses electrical energy for both the propulsion energy required to propel the ship and the onboard energy (onboard load) required for activities on board. The ship system of the present invention has both a generator from a generator motor and a storage battery as its electricity supply source, and achieves energy conservation by switching the electricity supply source according to the remaining charge of the storage battery. Below, we will explain the basic configuration of the ship system of the present invention, as well as examples of control according to the remaining charge of the storage battery and control according to the navigation situation.

(Basic configuration of ship system)
Fig. 1 is a schematic explanatory diagram of the basic configuration of a battery-equipped electric propulsion system of the present invention. In the figure, 1 is a main engine, and in the present invention, a propulsion motor is used instead of an internal combustion engine. The main engine 1 can provide propulsive force to a propulsion means 2 (e.g., a propeller) via a clutch (not shown). The clutch and the propulsion means 2 are not particularly limited, and those conventionally used in ships can be appropriately used.

3 is a storage battery, which is not for one-time use, but can repeatedly store electricity by charging, and can also repeatedly extract and use the stored electricity. For example, a conventionally known storage battery such as a lead storage battery, a lithium ion storage battery such as a lithium ion secondary battery or a lithium ion polymer secondary battery, a nickel metal hydride storage battery, or a nickel cadmium storage battery can be used. In the present invention, it is preferable to use a lithium ion storage battery as the storage battery because of the large amount of stored electricity per weight. The storage battery 3 is configured to supply power to the main engine 1 and/or the onboard load 4 via an inverter (INV). Therefore, it is preferable that the storage battery 3 has a capacity that can effectively function as a propulsion force for the ship and can sufficiently supply electricity as onboard power, and its capacity is preferably 100 kW to 1,000,000 kW.

5 is a power generating engine, which is generally an internal combustion engine that uses fuel to generate mechanical energy. The power generating engine 5 is configured to convert the generated mechanical energy into electrical energy using a generator 6, and to supply power to the main engine 1 and/or the storage battery 3 and/or the onboard loads 4 via a converter (CNV).

2 and 3 show schematic diagrams of the control of the battery-equipped electric propulsion ship system of the present invention when the remaining battery charge is low and when it is sufficient. In the present invention, (i) when the remaining battery charge of the battery 3 is low, at or below a capacity X selected from 0 to 15%, preferably 3 to 12%, and more preferably 4 to 10% of the rated capacity, the generator motor 5 is configured to generate power and supply it to the battery 3 as shown by the arrow in FIG. 2, and to optionally supply it to the main engine 1 and/or the loads on board the ship. At this time, the battery 3 does not supply power to anything else, but is solely dedicated to receiving and storing power. This generation and supply of power by the generator motor 5 continues until the remaining battery charge of the battery 3 is sufficient, at a capacity Y selected from 90 to 100%, preferably 92 to 99%, and more preferably 93 to 98% of the rated capacity.

Then, (ii) after the remaining charge of the storage battery 3 becomes sufficient, such as capacity Y, the generator motor 5 is stopped, and the storage battery 3 is configured to supply power to the main engine 1 and/or the onboard loads 4, as shown by the arrow in Figure 3. At this time, since the generator motor 5 is stopped, it does not generate power, and power supply is solely performed by the storage battery 3. This supply of power from the storage battery 3 continues until the remaining charge of the storage battery 3 again becomes low, such as capacity X. After this, the series of operations (i) and (ii) are configured to be repeated.

In the above case (i), it is preferable that the power generation of the generator engine is performed at a constant load in the most fuel-efficient state. This improves the fuel consumption rate of the generator engine and improves fuel efficiency. In addition, in the above case (ii), the power generation of the generator engine is stopped, making it possible to operate the ship without using the internal combustion engine at all. In that case, it is expected that there will be effects on the hardware issues caused by the recent crew shortage, such as improving the living environment on board by reducing vibration and noise, and reducing and simplifying maintenance work.

It is preferable to install two or more generators capable of supplying power to the main engine and/or the storage battery and/or the onboard loads on the ship. In this case, it is preferable that the first generator is used preferentially to supply power to the main engine and/or the storage battery and/or the onboard loads, and the second generator is used as an alternative power source in the event of failure and/or maintenance of the first generator, or as an assist power source for the main engine during high-speed navigation operating at 80% or more of the maximum output of the main engine.

(Control during normal navigation)
FIG. 4 shows a schematic diagram of the control of the battery-equipped electric propulsion ship system of the present invention during normal sailing. In FIG. 4, the flow of energy is indicated by arrows. During normal sailing, the main engine 1 is operated at 50% or more of its maximum output, and the main engine 1 provides its energy to the propulsion means 2 through the clutch. Therefore, the main engine 1 requires a relatively large amount of power, and when the remaining charge of the storage battery 3 is reduced to the above-mentioned capacity X or less, the power supply to the main engine 1 and the onboard load 4 is configured to be performed by the power from the generator motor 5, not from the storage battery 3, as shown in FIG. 4. The power supply from the generator motor 5 continues until the remaining charge of the storage battery 3 is sufficient, such as the above-mentioned capacity Y. After the remaining charge of the storage battery 3 becomes sufficient, the generator motor 5 is stopped, as shown in FIG. 3, and the main engine 1 and the onboard load 4 are not supplied with power from the generator motor 5, but are supplied with power exclusively from the storage battery 3. During normal sailing, the above-mentioned series of operations (i) and (ii) are repeated in this manner.

(Control during slow sailing)
FIG. 5 is a schematic diagram showing the control of the battery-equipped electric propulsion ship system of the present invention during low-speed sailing. In FIG. 5, the flow of energy is indicated by arrows. Low-speed sailing refers to sailing at 10 knots or less, or even 3 to 10 knots with combined power. Low-speed sailing is generally performed in short distance sailings such as within a port or a bay. During low-speed sailing, the power required for the main engine 1 is relatively small, and as shown in FIG. 5, unless the remaining capacity of the storage battery is reduced to the aforementioned capacity X or less, the power generating engine 5 is stopped, so that no power is supplied from the power generating engine 5, and the power of the main engine 1 and the onboard load 4 is controlled to be supplied from the storage battery 3. During low-speed sailing, the above-mentioned series of operations (i) and (ii) are repeated in this manner.

(Control during anchorage)
FIG. 6 shows a schematic diagram of the control of the battery-equipped electric propulsion ship system of the present invention when the ship is anchored. In FIG. 6, the flow of energy is indicated by arrows. When the ship is anchored, the main engine 1 is not used because there is no need to propel the ship. Therefore, the generator prime mover 5 can be controlled to stop and supply power only to the onboard loads as shown in FIG. 6 unless the remaining capacity of the storage battery 3 becomes low below the aforementioned capacity X. Also, when the ship is anchored, the storage battery 3 and/or the onboard loads 4 can be supplied with power from a land power source (not shown). When the ship is anchored, the above-mentioned series of operations (i) and (ii) are repeated in this manner.

The battery-equipped electric propulsion ship system of the present invention uses electric motors exclusively for ship propulsion without using an internal combustion engine, while controlling the operation of the generator motor and the supply of power in the most efficient manner according to the remaining charge of the storage battery and the operating conditions. This makes it possible to provide an electric propulsion ship with high energy saving effects and low maintenance costs, making it extremely useful in the industry.

1 Main engine 2 Propulsion means 3 Storage battery 4 Onboard load 5 Generator prime mover 6 Generator CNV Converter INV Inverter

Claims (5)

A battery-equipped electric propulsion ship system including a main engine which is a propulsion motor, a storage battery, a generator prime mover, and a propulsion means for propelling a hull,
a main engine configured to provide propulsive power to the propulsion means;
the battery is configured to power the main engine and/or the onboard loads;
the generator prime mover is configured to generate electricity to power the main engine and/or the battery and/or the onboard loads;
(i) when the remaining charge of the storage battery becomes equal to or less than capacity X selected from 0 to 15% of the rated capacity, the generator-motor generates electricity to supply power to the storage battery and optionally supplies power to the main engine and/or onboard loads until the remaining charge of the storage battery becomes capacity Y selected from 90 to 100% of the rated capacity, (ii) after the remaining charge of the storage battery reaches capacity Y, the generator-motor is stopped and the storage battery supplies power to the main engine and/or onboard loads again until the remaining charge of the storage battery becomes equal to or less than capacity X, and thereafter the operations of (i) and (ii) are repeated ;
At least two electric generating engines are installed on board the ship, of which the first electric generating engine is used preferentially to supply power to the main engine and/or the battery and/or the onboard loads, and the second electric generating engine is used as an alternative source of power during failure and/or maintenance of the first electric generating engine, or as a source of assist power for the main engine during high-speed voyage operating at 80% or more of the maximum output of the main engine.
A battery-equipped electric propulsion ship system comprising: The battery-equipped electric propulsion ship system according to claim 1, characterized in that the power generation of the power generating motor in case (i) is performed at a constant load. 3. The battery-equipped electric propulsion ship system according to claim 1 or 2, characterized in that, during normal navigation in which the ship is operated at 50% or more of the maximum output of the main engine, (i) when the remaining charge of the storage battery falls below capacity X selected from 0 to 15% of the rated capacity, the generator motor generates electricity to supply power to the storage battery and also supplies power to the main engine and onboard loads until the remaining charge of the storage battery reaches capacity Y selected from 90 to 100% of the rated capacity, and (ii) after the remaining charge of the storage battery reaches capacity Y, the generator motor is stopped and the storage battery supplies power to the main engine and onboard loads again until the remaining charge of the storage battery falls below capacity X, and thereafter the operations of (i) and (ii) are repeated. 4. The battery-equipped electric propulsion ship system according to any one of claims 1 to 3, characterized in that, during low-speed navigation at 10 knots or less, the generator prime mover is stopped and the storage battery can be controlled to supply power to the main engine and onboard loads unless the remaining charge of the storage battery falls below capacity X selected from 5 to 15 % of the rated capacity. 5. The battery-equipped electric propulsion ship system according to any one of claims 1 to 4 , characterized in that it is used on an inland ship with a gross tonnage of 100 tons or more and less than 5,000 tons.