JP5767059B2 - Electric propulsion ship - Google Patents

Description

  The present invention relates to an electric propulsion type ship that supplies electricity generated by a generator to an electric motor to propel the ship.

  Conventionally, cargo ships such as bulk carriers and tankers have been driven by propellers for propulsion using large diesel engines (main engines). This large cargo ship has, for example, one main engine and three auxiliary generators (one of which is for backup). This auxiliary generator is configured by combining a medium-sized medium speed diesel engine and a generator.

  FIG. 3 shows a schematic diagram of this ship. The ship 20 includes a large low-speed diesel engine (main engine) 21, a propeller for propulsion (hereinafter referred to as a propeller) 3X, and three auxiliary generators 22. The auxiliary generator 22 has a normal circuit 23 for connecting to equipment used in the ship (hereinafter referred to as the ship load 10). Here, the main machine 21 has an output of 10,000 kW and a size of 8.6 × 3.2 × 6.5 m, and the auxiliary generator 22 has an output of 400 kW and 2.5 × 1.5 × 4.5 m. It becomes the size of. The output and size of the main engine 21 and the auxiliary generator 22 vary depending on the scale of the ship 20.

  Next, operation | movement of this ship 20 is demonstrated. The ship 20 controls the navigation speed by controlling the rotational speed of the main engine 21 (about 100 rpm). The auxiliary generator 22 generates power by fixing the rotational speed at a so-called medium speed of about 500 to 1500 rpm. The electricity generated by the auxiliary generator 22 is AC electricity having a voltage of 440 V and a frequency of 60 Hz (or 50 Hz). This electricity is normally sent into the ship through the circuit 23, and is used as a power source for navigation equipment, various pumps, various lighting, and cabin living facilities (inboard load 10). The auxiliary generator 22 is usually operated by one or two units, and one unit is used for backup. That is, the maximum power generation amount of the auxiliary generator 22 is 800 kW (when two units are operating).

  Here, the definitions of the low speed diesel engine and the medium speed diesel engine are as follows. In the 3S class marine engine mechanics instruction manual, the low speed is defined as 500 rpm or less, and the medium speed is defined as greater than 500 rpm and less than 1500 rpm. In addition, the Japan Shipowners Association defines that the low speed is 300 rpm or less, the medium speed is greater than 300 rpm, and less than 1000 rpm.

  On the other hand, an electric propulsion type ship has been proposed in which the ship has an electric motor (motor) instead of the main engine, and the propeller is rotated by the motor (see, for example, Patent Document 1). FIG. 4 shows a schematic diagram of an example of an electric propulsion type ship (hereinafter referred to as an electric propulsion ship 1X). The electric propulsion ship 1X is configured by combining a motor 2X instead of a main engine, a variable speed medium-speed engine 24 that supplies electric power to the motor 2X, and a generator. Further, for example, three auxiliary generators 22 for supplying electric power to the inboard load 10 and a normal circuit 23 are provided.

  Next, the operation of the electric propulsion ship 1X will be described. The electric propulsion ship 1X controls the navigation speed by controlling the rotation speed of the variable-speed medium-speed engine 24. Further, normal power (voltage 440 V, frequency 60 Hz) supplied to the inboard load 10 is generated by the auxiliary generator 22. This is because the electricity generated by the variable-speed medium-speed engine 24 changes in voltage and frequency and cannot be used as normal power supplied to the inboard load 10. Further, the electric propulsion ship 1X does not have an inverter that converts the frequency of the generated electricity.

  With the above-described configuration, the electric propulsion ship 1X can realize an increase in the size of the hold as compared with the ship 20 equipped with a conventional diesel engine (main engine).

  However, the electric propulsion ship 1X has the following problems. First, power generation by the variable speed medium speed engine 24 has a problem that fuel efficiency is poor. The variable-speed medium-speed engine 24 generally has lower fuel efficiency than the low-speed engine and repeats acceleration and deceleration control, so that fuel efficiency is reduced. Generally, a diesel generator can improve fuel efficiency by operating at a specific speed as much as possible.

  Secondly, there is a problem that it is not possible to realize a sufficiently large cargo hold. This is because the variable speed medium-speed engine 24 having the same output (for example, 10,000 kW) and the motor 2X are installed instead of the main engine, so that the volume of these devices cannot be made sufficiently small.

  Thirdly, the power generation by the variable speed medium speed engine 24 has a problem that the cost of the engine 24 and associated equipment is high. This is because the cost of the variable speed medium speed engine 24 itself is high. In addition to the variable speed medium speed engine 24, the cost of the control system for controlling the variable speed medium speed engine 24 from the engine room, the bridge, and the like is high.

JP 2010-241194 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electric propulsion ship with improved volumetric efficiency in the engine room and improved fuel efficiency at the time of navigation. It is to provide at low cost.

Electrical propulsion boat according to the present invention for achieving the above object, a propulsion motor for driving the propulsion propeller, the electric propulsion boat having a generator, a generator of multiple, connected to the generator that a low-frequency circuit, and the low-frequency circuit to the propulsion motor which is connected via a frequency control device, via a frequency and voltage converter to said frequency circuit between said generator the frequency control device a normal circuit connected, and a ship load connected to the normal circuit, the generator is controlled to a state where the rotation speed is constant, as the frequency of the alternating current power is less than 5 0 Hz It has the structure controlled by this.

  With this configuration, the fuel efficiency of electric propulsion can be improved. This is because the rotational speed of the generator can be low (50 rpm to 250 rpm) and constant. Moreover, the volumetric efficiency in the engine room can be improved. This is because the degree of freedom of the installation position of the equipment in the engine room is improved by the configuration in which a plurality of generators are installed instead of the large low-speed diesel engine. In addition, since the frequency of the electricity to generate is made smaller than 50 Hz, the rotation speed of the generator can be reduced without increasing the size of the generator.

The frequency and voltage converter converts the electricity output from the generator, and the voltage of electricity flowing through the normal circuit can be set to 440 V and the frequency can be set to 60 Hz or 50 Hz. With this configuration, it is not necessary to separately install an onboard load generator, so that one type of generator can be used.

In the electric propulsion ship, the frequency of the alternating current generated by the generator is 10 Hz to 45 Hz. With this configuration, the fuel efficiency of the generator can be further improved.

Two frequency and voltage converters connected between the low frequency circuit and the normal circuit, a DC circuit connecting the two frequency and voltage converters to each other, and a secondary battery connected to the DC circuit The secondary battery can be configured to supply electricity to a low-frequency circuit or a normal circuit via a frequency and voltage converter according to the magnitude of the load of the propulsion motor and the ship load. With this configuration, the capacity and weight of the generator installed on the electric propulsion ship can be suppressed. This is because power can be supplied also from the secondary battery when the amount of power required for the propulsion motor and the inboard load increases.

  According to the electric propulsion ship according to the present invention, the electric propulsion ship that improves the volumetric efficiency in the engine room and improves the fuel efficiency at the time of navigation can be provided at low cost.

It is the figure which showed the outline of the electric propulsion ship of embodiment which concerns on this invention. It is the figure which showed the outline of the electric propulsion ship of different embodiment which concerns on this invention. It is the figure which showed the outline of the ship which has the conventional main engine. It is the figure which showed the outline of the conventional electric propulsion ship.

  Hereinafter, an electric propulsion ship 1 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an electric propulsion ship 1 according to an embodiment of the present invention. The electric propulsion ship 1 includes a propulsion motor (hereinafter referred to as a motor) 2 that drives a propeller (propeller) 3, a plurality of generators 4, and a low-frequency circuit 5 that connects the motor 2 and the generator 4 (solid line). Is shown). Further, the electric propulsion ship 1 has a frequency and voltage converter 7 connected to the low frequency circuit 5 and a normal circuit 6 (shown by a broken line) connecting the frequency and voltage converter 7 and the inboard load 10. . Here, the generator 4 has a size of 4.5 × 2.0 × 6.0 m when the output per unit is 2800 kW, for example. Moreover, the motor 2 can be comprised with an induction motor or an alternating current motor.

  The frequency and voltage converter 7 can be composed of an inverter, a power conditioner, a transformer, a combination thereof, and the like. Here, an inverter refers to a device that can convert AC to DC again through AC and adjust the frequency and voltage. The power conditioner is a unit in which an electronic power conversion device such as an inverter and a control / protection system are integrated. Furthermore, a transformer refers to a transformer that changes voltage.

  Next, operation | movement of this electric propulsion ship 1 is demonstrated. The electric propulsion ship 1 generates power with a plurality of generators 4 when navigating. The generator 4 is controlled so that the rotational speed is constant at a low rotational speed of about 100 to 250 rpm. The generator 4 generates an alternating current having a voltage of 6600 V and a frequency of 30 Hz, for example. Here, the rotation speed and size of the generator 4 are determined so that the frequency is a value smaller than 50 Hz, specifically 10 to 45 Hz, desirably 20 Hz to 40 Hz, and more desirably 25 Hz to 35 Hz. This alternating current flows through the low-frequency circuit 5 and is supplied to the motor 2 via a frequency control device (for example, an inverter) 8 (up to about 10,000 kW). The frequency control device 8 controls the rotation speed of the motor 2 and controls the navigation speed of the electric propulsion ship 1.

  A part of the alternating current (about 200 kw) is supplied to the ship load 10 via the frequency and voltage converter 7 and the normal circuit 6. Here, the current flowing through the normal circuit 6 has a voltage of 440 V and a frequency of 60 Hz (or 50 Hz).

  That is, the frequency of electricity generated by the generator 4 is adjusted to the motor 2 with a large amount of power used, and the power adjusted by the frequency and voltage converter 7 is supplied to the inboard load 10 side with a small amount of usage. . For this reason, the generator 4 can be reduced in speed (for example, 250 rpm or less) and downsized.

  The frequency control device 8 can be composed of an inverter, a power conditioner, a transformer, a combination thereof, and the like. Moreover, when the electric propulsion ship 1 navigates at low speed, some of the plurality of diesel generators 4 may be stopped. Furthermore, with regard to the frequency of AC electricity generated by the generator 4, the smaller the frequency is set, the smaller the diesel generator can be used. On the other hand, if the frequency is too small, the power generation efficiency of the generator will be reduced. It is desirable to determine the frequency and the size of the generator based on a balance between the two.

  With the above configuration, the following operational effects can be obtained. First, the fuel efficiency of the electric propulsion ship 1 can be improved. This is because the rotational speed of the generator 4 can be set to a low speed (100 rpm to 250 rpm) and a constant speed to improve thermal efficiency.

Second, the volumetric efficiency in the engine room can be improved. Specifically, since the volume of the generator 4 having the maximum size is about 54 m ³ , the installation location can be determined relatively freely. Conventionally, it is necessary to install a medium-speed engine (equivalent to the main engine) of about 180 m ³ , and this installation position is limited. In addition, when the rotation speed of a diesel generator is made low speed and it is going to generate electricity with a frequency of 60 Hz, the diameter of the shaft core of a generator will become large and a generator will become large.

  Third, the electric propulsion ship 1 can be introduced at low cost. This is because the rotational speed of the generator 4 is configured to be a constant speed, and it is not necessary to install a control system or the like that controls the rotational speed. Moreover, since the rotation speed of the generator 4 is low-speed rotation, the required maintenance frequency can be reduced significantly.

  Furthermore, since electric power can be supplied to the motor 2 and the inboard load 10 with one type of generator 4, the crew only needs to learn maintenance work for one type of generator, and the burden is reduced. In addition, the number of repair parts mounted on the electric propulsion ship 1 can be suppressed.

Fourth, the maximum load per unit area on the floor in the engine room can be reduced. That is, since generators of about 54 m ³ can be installed in a distributed manner, the amount of reinforcing members and the like required for the electric propulsion ship 1 can be reduced, and the construction cost of the electric propulsion ship 1 can be suppressed. Conventionally, it has been necessary to intensively install reinforcing members on the floor supporting a medium speed engine of about 180 m ³ .

FIG. 2 shows an electric propulsion ship 1a according to another embodiment of the present invention. The electric propulsion ship 1a includes two propulsion motors (motors) 2a that drive a counter-rotating propeller 3a, a plurality of generators 4a, and a low-frequency circuit 5a that connects the motor 2a and the generator 4a (shown by a solid line). have. The electric propulsion ship 1a has a frequency and voltage converter (for example, a power conditioner 7a) connected to the low frequency circuit 5a, and a DC circuit 9 (indicated by a one-dot chain line) connected to the power conditioner 7a. The secondary battery 11 is included. Furthermore, the electric propulsion ship 1 a has another power conditioner 7 a connected to the DC circuit 9 and an inboard load 10 connected to the power conditioner 7 a via the normal circuit 6. Here, if the output per generator is 2000 kW, for example, the generator 4 a has a size of about 43 m ³ .

  Next, operation | movement of this electric propulsion ship 1a is demonstrated. First, the generator 4a is controlled at a low rotational speed of about 100 to 250 rpm so that the rotational speed is constant, and power is generated. For example, the generator 4a generates an alternating current having a voltage of 6600 V and a frequency of 25 Hz. This alternating current flows through the low-frequency circuit 5a and is supplied to the motor 2a via a frequency control device (for example, an inverter) 8a. This frequency control device 8 controls the rotational speed of the motor 2 and controls the navigation speed of the electric propulsion ship 1a.

  A part of the alternating current is stored in the secondary battery 11 through the power conditioner 7 a and the direct current circuit 9. Alternatively, a part of the alternating current is supplied to the ship load 10 via the two power conditioners 7a, the direct current circuit 9, and the normal circuit 6. Further, the secondary battery 11 supplies electricity to the motor 2a and the inboard load 10 according to the load.

  With the above configuration, the following operational effects can be obtained. First, the volumetric efficiency in the engine room can be improved by, for example, a configuration in which a plurality of generators 4a of 2000 kW are installed. In the past, large generators (with an output of 10,000 kW level) were installed, so the installation location in the engine room was limited. On the other hand, the electric propulsion ship 1a has a configuration in which a plurality of medium-sized generators 4a (with an output of, for example, 2000 kW level) are installed, so that the degree of freedom of installation location is improved. Moreover, since the weight per generator is reduced, the usage amount of the reinforcing member necessary for the hull can be suppressed. As a result, the construction cost of the ship can be reduced and the construction period can be further shortened.

  2ndly, the structure which installs the secondary battery 11 can suppress the output total of the generator 4a which should be installed in the electric propulsion ship 1a. This is because power can be supplied also from the secondary battery 11 when the amount of power required for the motor 2a and the inboard load 10 increases.

  In addition, although the magnitude | size, output, etc. of the above-mentioned generator assume the cargo ship whose loading weight tonnage is about 56000 tons, this invention is not limited to said Example. Depending on the scale of the electric propulsion ship, the maximum output of the generator and the voltage of electricity to be generated can be arbitrarily determined.

1, 1a Electric propulsion ship 2, 2a Electric motor for propulsion (motor)
3, 3a Propeller 4 for propulsion, 4a Generator 5, 5a Low frequency circuit 6 Normal circuit 7, 7a Frequency and voltage converter 9 DC circuit 10 Inboard load 11 Secondary battery

Claims (4)

In an electric propulsion ship having a propulsion motor that drives a propeller for propulsion and a generator,
Between the multiple generators, the low-frequency circuit connected to the generator, and the propulsion motor, which is connected via the frequency control device in this low-frequency circuit, and said power generator and said frequency control device A normal circuit connected to the frequency circuit via a frequency and voltage converter, and an inboard load connected to the normal circuit ,
The generator is controlled to a state where the rotation speed is constant, electric propulsion ship characterized by having a configuration in which the frequency of the alternating current generator is controlled to be less than 5 0 Hz. The frequency and voltage converter, the converted electrical output from the generator, the normal 440V voltage of electricity flowing through the circuit, electrical propulsion boat according to frequency to claim 1, 60Hz or 50 Hz. Wherein the frequency of the alternating current generator is power generation, electric propulsion boat as claimed in 請 Motomeko 1 or 2 is 10Hz or 45Hz or less. The two frequency and voltage converters connected between the low frequency circuit and the normal circuit , a direct current circuit connecting the two frequency and voltage converters to each other, and a secondary connected to the direct current circuit A battery,
The said secondary battery supplies electricity to the said low frequency circuit or the said normal circuit via the said frequency and voltage converter according to the magnitude | size of the load of the said propulsion motor and the said ship load. An electric propulsion ship according to any one of the above.

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