Propulsion system, control program, and control method for vessel

Abstract

To provide a propulsion system, a control program, and a control method for a vessel capable of suppressing deterioration in fuel consumption along with load variation in a propulsion propeller in a vessel including an engine and a rotary machine.SOLUTION: A propulsion system for a vessel includes an engine, a rotary machine, a power converter, and a controller, the controller acquires torque of the engine, torque of the rotary machine, angular speed of the rotary machine, and prefixed moment of inertia for rotational axis conversion of the rotary machine, calculates an estimation value for load torque of the propulsion propeller by using equation of motion for the rotary axis system of the rotary machine, generates a torque command value regarding the torque to be generated by the rotary machine from the propulsion force command value, and compensates the torque command value to cancel fluctuation component of the estimation value of the load torque.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a propulsion system, a control program, and a control method for a ship. [Background technology]

[0002] BACKGROUND ART In a ship capable of driving a propulsion propeller using a main engine, a ship propulsion system is known that is equipped with a rotating machine to generate electricity using the engine's excess output or to generate driving force to assist the propulsion force.

[0003] In such a vessel, even when the engine is maintained at a predetermined rotational speed, the load on the propeller fluctuates due to changes in water surface conditions caused by worsening weather, etc. Fluctuations in the load on the propeller cause fluctuations in engine torque, resulting in a deterioration in fuel efficiency.

[0004] As a configuration for suppressing deterioration in fuel efficiency due to the above-mentioned load fluctuations in a ship equipped with an engine and a motor-generator, for example, Patent Document 1 listed below describes a method of regarding an increase or decrease in a fuel supply command value for the engine as an increase or decrease in load, and correcting a power command value for the motor-generator using a value obtained by adding a fluctuation component of the engine fuel supply command value to a fluctuation component of the engine speed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-227110 Summary of the Invention [Problem to be solved by the invention]

[0006] However, while the method described in Patent Document 1 can generate a correction command in a direction that cancels out load fluctuations in the propulsion propeller, it is difficult to accurately determine the magnitude of the correction command value for canceling out the load fluctuations. Therefore, there is room for improvement in control methods for suppressing deterioration in fuel efficiency due to load fluctuations in ships equipped with rotating machines such as engines and motor generators.

[0007] The present disclosure has been made in consideration of the above, and aims to provide a ship propulsion system, control program, and control method that can suppress deterioration of fuel efficiency due to load fluctuations in the propulsion propeller in a ship equipped with an engine and a rotary machine. [Means for solving the problem]

[0008] A propulsion system according to one aspect of the present disclosure is a propulsion system for a vessel including an engine mechanically connected to a propulsion propeller, a rotating machine mechanically connected to the engine and capable of generating electricity using the driving force of the engine or transmitting power to the propulsion propeller, a power converter electrically connected to the rotating machine, and a controller that controls the engine and the power converter based on a propulsion force command value, wherein the controller acquires the torque of the engine, the torque of the rotating machine, the angular velocity of the rotating machine, and a predetermined moment of inertia of the rotating machine converted into a rotating shaft, calculates an estimate of the load torque of the propulsion propeller using an equation of motion of a rotating shaft system of the rotating machine, generates a torque command value for the torque to be generated in the rotating machine from the propulsion force command value, and corrects the torque command value so as to cancel out fluctuation components in the estimated value of the load torque.

[0009] A control program according to another aspect of the present disclosure is a control program for a ship including an engine mechanically connected to a propulsion propeller, a rotating machine mechanically connected to the engine and capable of generating electricity using the driving force of the engine or transmitting power to the propulsion propeller, a power converter electrically connected to the rotating machine, and a controller that controls the engine and the power converter based on a propulsion force command value, wherein the control program causes the controller to acquire the torque of the engine, the torque of the rotating machine, the angular velocity of the rotating machine, and a predetermined moment of inertia converted into the rotating shaft of the rotating machine, calculate an estimated value of the load torque of the propulsion propeller using an equation of motion of a rotating shaft system of the rotating machine, generate a torque command value for the torque to be generated in the rotating machine from the propulsion force command value, and correct the torque command value so as to cancel out a fluctuation component in the estimated value of the load torque.

[0010] According to another aspect of the present disclosure, a control method includes: an engine mechanically connected to a propulsion propeller; A control method for a ship including a rotating machine mechanically connected to the engine and capable of generating electricity using the driving force of the engine or transmitting power to the propulsion propeller, a power converter electrically connected to the rotating machine, and a controller that controls the engine and the power converter based on a thrust command value, the method comprising: acquiring the torque of the engine, the torque of the rotating machine, the angular velocity of the rotating machine, and a predetermined moment of inertia of the rotating machine converted into a rotating shaft; calculating an estimated value of load torque of the propulsion propeller using an equation of motion of a rotating shaft system of the rotating machine; generating a torque command value for torque to be generated in the rotating machine from the thrust command value; and correcting the torque command value so as to cancel out a fluctuation component in the estimated value of load torque. [Effects of the Invention]

[0011] According to the present disclosure, in a vessel equipped with an engine and a rotary machine, it is possible to suppress deterioration in fuel efficiency due to load fluctuations in a propulsion propeller. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a marine vessel propulsion system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing an outline of the correction command value calculation circuit in this embodiment. [Figure 3] FIG. 3 is a graph showing changes over time in the estimated value Tp of the load torque, the torque Tmg of the motor generator, and the equivalent value Tme of the engine torque in this embodiment. [Figure 4] FIG. 4 is a graph showing the time variations of the estimated value Tp of the load torque, the torque Tmg of the motor generator, and the equivalent value Tme of the engine torque when the motor generator is in a driving state. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments will be described in detail with reference to the drawings. Note that, in the following, the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant description thereof will be omitted.

[0014] [Embodiment Mode] 1 is a block diagram showing a schematic configuration of a propulsion system for a ship according to an embodiment of the present disclosure. The ship in this embodiment is a hybrid propulsion ship in which an engine 3 and a motor-generator 4, which is a rotating machine, can be used as sources of driving force for a propulsion propeller 2.

[0015] The propulsion system 1 in this embodiment includes a propulsion propeller 2, an engine 3, a motor generator 4, and a first power converter 7. The propulsion propeller 2 is a controllable pitch propeller configured so that the blade angle can be changed in accordance with a thrust command value.

[0016] The engine 3 is a gas engine that generates driving force using fuel including fuel gas obtained by vaporizing liquefied natural gas. The engine 3 may be a gas-fired engine that burns fuel gas obtained by vaporizing liquefied natural gas exclusively, a dual-fuel engine that can switch between burning fuel gas and liquid fuel such as heavy oil, or a diesel engine that burns liquid fuel.

[0017] The engine 3 and the motor generator 4 are mechanically connected to the propulsion propeller 2 via a reduction gear 5. The motor generator 4 is electrically connected to a first power converter 7. The first power converter 7 is interposed between the DC wiring 6 and the motor generator 4. The motor generator 4 is able to transmit power to the propulsion propeller 2 by generating power from electric power supplied through the DC wiring 6. At this time, the first power converter 7 converts the DC voltage in the DC wiring 6 into an AC voltage and outputs it to the motor generator 4. Furthermore, the motor generator 4 can also generate power using the driving force of the engine 3 and supply the power to the DC wiring 6. At this time, the first power converter 7 converts the AC voltage generated by the electric power generated by the motor generator 4 into a DC voltage and outputs it to the DC wiring 6.

[0018] Furthermore, a power storage device 9 is connected to the DC wiring 6. The power storage device 9 is a secondary battery, a capacitor, or the like, and may include a power converter such as a DC-DC converter that converts the DC voltage of the DC wiring 6 into a predetermined DC voltage. Furthermore, an AC wiring 11 is connected to the DC wiring 6 via a second power converter 10. The second power converter 10 converts the DC voltage of the DC wiring 6 into an AC voltage and outputs it to the AC wiring 11, and converts the AC voltage of the AC wiring 11 into a DC voltage and outputs it to the DC wiring 6. Electrical equipment in the ship may be connected to the AC wiring 11 or the DC wiring 6.

[0019] According to the propulsion system 1, the engine 3, which is a mechanical propulsion unit, and the motor generator 4, which is an electric propulsion unit, can cooperatively generate propulsive force for the vessel. Furthermore, according to the propulsion system 1, surplus propulsive force generated by the engine 3 can be recovered as electric power by the motor generator 4, and the electric power can be supplied to the AC wiring 11 or stored in the capacitor 9.

[0020] The propulsion system 1 includes a controller 14. The controller 14 includes a processing circuit 15 that performs various types of signal processing. The processing circuit 15 includes a computer, such as a microcontroller, a personal computer, or a programmable logic controller (PLC). More specifically, the processing circuit 15 includes a processor, a memory, and peripheral circuits. The processor includes, for example, a CPU or an MPU. The memory includes, for example, a ROM, a RAM, a register, non-volatile storage, and the like. The peripheral circuits include, for example, an input / output interface. The controller 14 is connected to an operation input device 16 that operates the hybrid propulsion vessel. The controller 14 may be connected to a monitor that displays the control status, a speaker that outputs audio, or the like.

[0021] It should be noted that the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this specification, a circuit, unit, means, or module is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where hardware is a processor, which is considered a type of circuit, the circuit, unit, or means is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0022] A control program for controlling the controlled object is stored in the memory of the controller 14. The controller 14 controls the controlled object based on the control program. As described above, various calculations executed by the controller 14 based on the control program are realized by the processing circuit 15. The controlled objects of the controller 14 include the propulsion propeller 2, the engine 3, and the first power converter 7. The controller 14 may be configured as one controller that controls these components 2, 3, and 7, or may be configured with two or more controllers. The controller 14 may also be configured to be able to control the storage battery 9, the second power converter 10, or a load connected to the AC wiring 11.

[0023] The controller 14 controls the blade angle of the propulsion propeller 2, the rotation speed of the engine 3, and the first power converter 7 based on the propulsion force command value Fo. The propulsion force command value Fo is input from an operation input device 16. The operation input device 16 may be configured, for example, as an operation lever or operation handle for adjusting the speed of the vessel and switching between forward and reverse. For example, the operation lever is configured so that a position where it is operated a maximum amount in a first direction corresponds to the maximum vessel speed on the forward side, a position where it is operated a maximum amount in a second direction opposite to the first direction corresponds to the maximum vessel speed on the reverse side, and a neutral position corresponds to a vessel speed of 0.

[0024] The operation input device 16 generates a larger propulsion force command value Fo as the boat speed corresponding to the operation position of the operation lever increases. The controller 14 generates a blade angle target value Wo for the propulsion propeller 2 based on the propulsion force command value Fo. The controller 14 generates a blade angle target value Wo such that the blade angle increases as the propulsion force command value Fo increases. For example, when the operation lever is in a position corresponding to the first direction, a blade angle target value Wo that results in a positive blade angle is generated, and when the operation lever is in a position corresponding to the second direction, a blade angle target value Wo that results in a negative blade angle is generated.

[0025] In this embodiment, the propulsion system 1 is equipped with a blade angle sensor 17 that detects the blade angle of the propulsion propeller 2. The controller 14 acquires the value detected by the blade angle sensor 17 and performs feedback control so that the blade angle of the propulsion propeller 2 becomes the blade angle target value Wo.

[0026] Furthermore, the controller 14 controls the rotation speed of the engine 3 in accordance with the thrust force command value Fo. The controller 14 generates an engine rotation speed target value Eo from the thrust force command value Fo. The controller 14 controls the engine 3 so that the rotation speed of the engine 3 is maintained at the engine rotation speed target value Eo.

[0027] Furthermore, the controller 14 controls the first power converter 7 in accordance with the power conversion command value. For example, when the propulsion force command value Fo is smaller than the output of the engine 3 corresponding to the engine speed target value Eo while the engine 3 is operating, the controller 14 controls the first power converter 7 to generate electricity by rotating the motor generator 4 with the power of the difference, and to supply the electricity generated by the motor generator 4 to the DC wiring 6. The electricity supplied from the first power converter 7 to the DC wiring 6 is supplied to the AC wiring 11 via the second power converter 10. The surplus electricity is supplied from the DC wiring 6 to the capacitor 9 and stored in the capacitor 9.

[0028] For example, when the propulsive force command value Fo is equal to or greater than a reference value corresponding to a predetermined reference boat speed, the controller 14 controls the engine 3 to maintain a predetermined engine speed target value Eo. For example, if the operating positions of the control lever for setting the propulsive force command value Fo in the operation input device 16 are divided into five stages in ascending order of boat speed target values ​​corresponding to the forward propulsive force command value Fo: STOP, dead slow (D.SLOW), half (HALF), full (FULL), and navigation full (Nav. FULL), the reference boat speed may be set to full.

[0029] During steady sailing when the propulsion force command value Fo is constant at a value equal to or greater than a reference value, the controller 14 executes correction control in accordance with load fluctuations on the propulsion propeller 2. For example, the controller 14 may detect the ship speed, and determine that the ship is sailing steadily when the detected ship speed is within a predetermined range based on a target ship speed value corresponding to the propulsion force command value Fo, and execute correction control. In the correction control, the controller 14 acquires the torque Te of the engine 3, the torque Tmg of the motor-generator 4, the angular velocity ω of the motor-generator 4, and the moment of inertia J of the motor-generator 4 converted into the rotating shaft 4a.

[0030] The propulsion system 1 includes one or more sensors 18 that acquire engine parameters such as a fuel injection amount, engine speed, intake pressure, and fuel heat value. The controller 14 calculates a virtual load using the engine parameters acquired from the sensors 18 and generates a torque Te of the engine 3 from the virtual load. If an engine controller that controls the engine 3 is configured as a controller separate from the controller 14, the engine controller may calculate a virtual load using the engine parameters acquired from the sensors 18 and transmit information about the virtual load to the controller 14. In this case, the controller 14 may acquire information about the virtual load from the engine controller and generate the torque Te of the engine 3 from the acquired virtual load. Alternatively, the propulsion system 1 may include a torque sensor that detects the torque Te of the engine 3, and the controller 14 may acquire the torque Te of the engine 3 detected by the torque sensor.

[0031] Furthermore, the controller 14 generates a torque command value To for the motor generator 4 from the thrust force command value Fo and the engine speed target value Eo. When the output of the engine 3 corresponding to the engine speed target value Eo is greater than the thrust force command value Fo, the motor generator 4 is driven by the surplus output to generate electricity. The controller 14 calculates the torque command value To from a power generation command value for the motor generator 4 based on the surplus output and the rotation speed of the motor generator 4. The controller 14 acquires the torque command value To as the torque Tmg of the motor generator 4. A value obtained by actually measuring the torque of each rotating shaft using a torque sensor or an output torque value calculated by the first power converter 7 may be used as the torque Tmg of the motor generator 4.

[0032] The propulsion system 1 is equipped with a rotation speed detector 19 that detects the rotation speed of the motor generator 4. The controller 14 calculates the angular velocity ω from the rotation speed N of the motor generator 4. Furthermore, the angular velocity ω of the motor generator 4 may be calculated from the rotation speed of the rotating shaft of the engine 3 or the propulsion propeller 2. In this case, the controller 14 converts the detected rotation speed using the reduction ratio g of the reducer 5 into the rotation speed of the rotating shaft 4a of the motor generator 4.

[0033] The moment of inertia J of the motor generator 4 converted into the rotating shaft 4a is a value determined based on a design value and is stored in advance in a storage device.

[0034] The controller 14 calculates an estimated value Tp of the load torque of the propulsion propeller 2 using these acquired values ​​and the equation of motion of the rotating shaft system of the motor generator 4. The equation of motion of the rotating shaft system of the motor generator 4 is expressed as J(dω / dt) = Tmg + Tme - Tp. Therefore, the estimated value Tp of the load torque of the propulsion propeller 2 can be expressed from this equation of motion as Tp = Tmg + Tme - J(dω / dt). Here, Tme is a value obtained by converting the torque Te of the engine 3 to the rotating shaft 4a of the motor generator 4.

[0035] Here, if the water surface conditions change, for example, due to bad weather, causing swells, the propulsion propeller 2 may temporarily move in and out of the water. This can cause the load on the propulsion propeller 2 to fluctuate even during steady sailing. When the load on the propulsion propeller 2 fluctuates, the torque Te of the engine 3 fluctuates due to the load fluctuation. On the other hand, because the motor-generator 4 operates to maintain the torque command value To of the first power converter 7, the torque Tmg of the motor-generator 4 does not fluctuate due to the load fluctuation on the propulsion propeller 2.

[0036] In this embodiment, in order to suppress fluctuations in the torque Te of the engine 3 due to fluctuations in the load on the propulsion propeller 2, the torque command value To is corrected so as to fluctuate the torque Tmg of the motor generator 4. The controller 14 calculates a correction command value Tc for correcting the torque command value To using the calculated estimated value Tp of the load torque. For this purpose, the processing circuit 15 of the controller 14 includes a correction command value calculation circuit 20.

[0037] 2 is a block diagram showing an outline of the correction command value calculation circuit in this embodiment. The correction command value calculation circuit 20 includes a unit conversion circuit 21, a pseudo differentiator 22, multipliers 25 and 26, low-pass filters 27 and 28, an adder / subtractor 29, and a high-pass filter 30. The unit conversion circuit 21 converts the rotation speed N [min -1] is converted into angular velocity ω [rad / s]. The conversion formula is expressed as ω = 2πN / 60. When the angular velocity ω is directly input to the correction command value calculation circuit 20, the unit conversion circuit 21 is not necessary.

[0038] The pseudo differentiator 22 includes a differentiator 23 and a first low-pass filter 24. The differentiator 23 differentiates the angular velocity ω. The first low-pass filter 24 removes high-frequency components from the output of the differentiator 23. For example, the transfer function of the pseudo differentiator 22 is expressed as s / (1+Ts) using a time constant T, and the transfer function of the first low-pass filter 24 is expressed as 1 / (1+Ts). The pseudo differentiator 22 outputs the differential value of the angular velocity ω after passing through the first low-pass filter 24 as the rotational acceleration dω / dt. The first multiplier 25 multiplies the moment of inertia J of the motor-generator 4 converted into the rotating shaft 4a by the rotational acceleration dω / dt and outputs J(dω / dt).

[0039] A second multiplier 26 multiplies the torque Te of the engine 3 by a gain g corresponding to the reduction ratio to calculate a torque equivalent value Tme, which converts the torque Te of the engine 3 into torque on the rotating shaft 4a. A second low-pass filter 27 is applied to the torque equivalent value Tme of the engine 3. Similarly, a third low-pass filter 28 is applied to the torque Tmg of the motor-generator 4. An adder-subtractor 29 calculates an estimated value of the load torque of the propulsion propeller 2 using the above equation of motion. More specifically, the adder-subtractor 29 adds the torque Tmg of the motor-generator 4, which is the output of the third low-pass filter 28, to the torque equivalent value Tme of the engine 3, which is the output of the second low-pass filter 27, and subtracts therefrom the product J(dω / dt) of the rotational acceleration dω / dt and the moment of inertia J, which is the output of the first multiplier 25. The output of the adder-subtractor 29 becomes the estimated value Tp of the load torque of the propulsion propeller 2.

[0040] The pseudo differentiator 22 applies the first low-pass filter 24 to the differential value of the angular velocity ω of the motor-generator 4, and as a result, the rotational acceleration dω / dt output from the pseudo differentiator 22 has a phase lag with respect to the torque Tmg of the motor-generator 4 and the torque equivalent value Tme of the engine 3. Therefore, when the adder-subtractor 29 subtracts J(dω / dt) from the torque sum Tmg+Tme, the phases do not match, and the estimated value Tp of the load torque cannot be calculated appropriately.

[0041] Therefore, low-pass filters 27 and 28 similar to first low-pass filter 24 are also applied to torque Tmg of motor-generator 4 and torque equivalent value Tme of engine 3, respectively. This makes it possible to eliminate the phase difference between the torque sum Tmg+Tme and J(dω / dt) when adder-subtractor 29 calculates estimated value Tp of load torque using the equation of motion. As a result, estimated value Tp of load torque calculated by adder-subtractor 29 can be appropriately calculated. For this reason, second low-pass filter 27 and third low-pass filter 28 are low-pass filters having the same transfer function as first low-pass filter 24. In other words, the time constant T of second low-pass filter 27 and third low-pass filter 28 is set to the same value as the time constant T of first low-pass filter 24.

[0042] The high-pass filter 30 extracts the fluctuation component of the load torque estimate Tp output from the adder / subtractor 29. At this time, the output of the high-pass filter 30 leads in phase the input load torque estimate Tp. Therefore, in the output of the high-pass filter 30, the phase of the load torque estimate Tp delayed by the first low-pass filter 24, the second low-pass filter 27, and the third low-pass filter 28 can be advanced, thereby reducing the phase difference between the output of the high-pass filter 30 and the actual load torque. The output of the high-pass filter 30 is output from the corrected command value calculation circuit 20 as the corrected command value Tc. The controller 14 corrects the torque command value To so as to cancel out the fluctuation component of the load torque estimate Tp. That is, the controller 14 adds the corrected command value Tc to the torque command value To. The controller 14 outputs a drive signal corresponding to the corrected torque command value To+Tc to the first power converter 7.

[0043] In this embodiment, the motor generator 4 functions as a generator. Therefore, the torque command value To is expressed as a negative value. In this case, the controller 14 corrects the torque command value To so that the amount of power generated by the motor generator 4 decreases as the estimated value Tp of the load torque increases, and increases as the estimated value Tp of the load torque decreases.

[0044] FIG. 3 is a graph showing changes over time in the load torque estimate Tp, motor-generator torque Tmg, and engine torque equivalent value Tme in this embodiment. The torque Tmg of the motor-generator 4 is expressed as the corrected torque command value To+Tc. The torque Tmg of the motor-generator 4 during power generation is expressed as a negative value. FIG. 3 shows an example in which the load torque of the propulsion propeller 2 fluctuates sinusoidally from time t1 to time t2. Due to the fluctuations in the load torque, the load torque estimate Tp calculated by the controller 14 also fluctuates over the period from time t1 to time t2.

[0045] As described above, when such a load torque fluctuation occurs, if the torque command value To is not corrected, the engine 3 will bear the load torque fluctuation. That is, a sinusoidal fluctuation occurs as indicated by the dashed line in the graph of the torque equivalent value Tme of the engine 3 in FIG. 3. On the other hand, by correcting the torque command value To, the amount of power generated by the motor-generator 4 fluctuates in accordance with the load torque fluctuation. As a result, fluctuations in the torque Te of the engine 3 due to the load torque fluctuation are suppressed. In the graph of the torque equivalent value Tme of the engine 3 in FIG. 3, fluctuations are also suppressed between time t1 and time t2 as indicated by the solid line.

[0046] As described above, with the above configuration, in a ship equipped with an engine 3 and a motor-generator 4, the concept of a disturbance observer is applied, and the load fluctuation itself in the propulsion propeller 2 is estimated using the equation of motion of the rotating shaft system of the motor-generator 4. Then, the torque command value To of the first power converter 7 is corrected so as to cancel out the load fluctuation in the propulsion propeller 2. In this way, the load fluctuation in the propulsion propeller 2 is borne by the motor-generator 4. As a result, it is possible to suppress the engine 3 from bearing the load fluctuation in the propulsion propeller 2, and to suppress fluctuations in the torque Te of the engine 3. Therefore, in such a ship, it is possible to suppress deterioration in fuel efficiency due to load fluctuations in the propulsion propeller 2. This makes it possible to realize a ship with a low environmental impact.

[0047] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various improvements, changes, and modifications are possible within the scope of the spirit of the present disclosure.

[0048] [Other embodiments] For example, in the above embodiment, the motor generator 4 generates power when the correction control is executed, but this is not limiting. That is, the controller 14 can execute the correction control even in a driving state in which the motor generator 4 generates a driving force for the propulsion propeller 2.

[0049] Fig. 4 is a graph showing the time variations of the load torque estimate Tp, motor-generator torque Tmg, and engine torque equivalent value Tme when the motor-generator 4 is in a driving state. As shown in Fig. 4, when the motor-generator 4 is in a driving state, the controller 14 corrects the torque command value To so that the output of the motor-generator 4 increases as the load torque estimate Tp increases and decreases as the load torque estimate Tp decreases. This causes the output of the motor-generator 4 to fluctuate in accordance with fluctuations in the load torque. As a result, fluctuations in the torque Te of the engine 3 due to fluctuations in the load torque are suppressed.

[0050] Furthermore, in the above embodiment, the engine 3 and the motor-generator 4 are connected in parallel to the propulsion propeller 2 via the reduction gear 5, but this is not limiting. For example, the propulsion system 1 may include an intermediate shaft type motor-generator 4 in which the rotor of the generator is fixed to an intermediate shaft connected between the output shaft of the engine 3 and the rotation shaft of the propulsion propeller 2.

[0051] Furthermore, in the above embodiment, the propulsion system 1 is illustrated as having a motor-generator 4 that can both generate electricity and transmit power to the propulsion propellers 2, but the correction control aspect of the present disclosure is applicable to any propulsion system 1 that is equipped with a rotating machine that can function as at least one of a power generation function and a power transmission function. In other words, the correction control aspect of the present disclosure is applicable to both cases where the rotating machine in the propulsion system 1 functions only as a generator and cases where the rotating machine in the propulsion system 1 functions only as an electric motor.

[0052] In the above embodiment, the propulsion system 1 is illustrated as being equipped with a controllable pitch propeller as the propulsion propeller 2, but the propulsion system may also be equipped with a propulsion propeller with a fixed blade angle. In this case, the engine speed when driving the propulsion propeller 2 with the output of the engine 3 may be varied in accordance with the target ship speed value corresponding to the thrust command value Fo.

[0053] In the above embodiment, an example has been shown in which the propulsion system 1 includes one controller 14 that controls multiple devices such as the engine 3 and the first power converter 7. Alternatively, the various signal processes of the controller 14 may be performed by two or more controllers. That is, the propulsion system 1 may include two or more controllers. For example, the propulsion system 1 may include an engine controller that controls the engine 3 and a converter controller that controls the first power converter 7.

[0054] The control program in the above embodiment may be configured as a program product that is provided by downloading from an external computer or recorded on a non-transitory recording medium that is readable by a computer, or may be configured as a computer product in which the control program is pre-installed.

[0055] Summary of this disclosure [Item 1] A propulsion system according to one aspect of the present disclosure is a propulsion system for a vessel including an engine mechanically connected to a propulsion propeller, a rotating machine mechanically connected to the engine and capable of generating electricity using the driving force of the engine or transmitting power to the propulsion propeller, a power converter electrically connected to the rotating machine, and a controller that controls the engine and the power converter based on a propulsion force command value, wherein the controller acquires the torque of the engine, the torque of the rotating machine, the angular velocity of the rotating machine, and a predetermined moment of inertia of the rotating machine converted into a rotating shaft, calculates an estimate of the load torque of the propulsion propeller using an equation of motion of a rotating shaft system of the rotating machine, generates a torque command value for the torque to be generated in the rotating machine from the propulsion force command value, and corrects the torque command value so as to cancel out fluctuation components in the estimated value of the load torque.

[0056] According to the above configuration, in a ship equipped with an engine and a rotating machine, the concept of a disturbance observer is applied, and the load fluctuations themselves in the propulsion propeller are estimated using the equation of motion of the rotating shaft system of the rotating machine. Then, the torque command value of the power converter electrically connected to the rotating machine is corrected so as to cancel out the load fluctuations in the propulsion propeller. This causes the motor-generator to bear the load fluctuations in the propulsion propeller. As a result, it is possible to suppress the engine from bearing the load fluctuations in the propulsion propeller, and to suppress engine torque fluctuations. Therefore, it is possible to suppress deterioration in fuel efficiency due to load fluctuations in the propulsion propeller in such a ship.

[0057] [Item 2] In the propulsion system of item 1, the controller may apply a differentiator and a low-pass filter to the angular velocity of the rotating machine to pseudo-differentiate the angular velocity of the rotating machine to calculate rotational acceleration, apply the same low-pass filter as applied to the angular velocity of the rotating machine to the torque of the engine and the torque of the rotating machine, and apply the rotational acceleration, the torque of the engine after application of the low-pass filter, and the torque of the rotating machine to the equation of motion. Applying a low-pass filter to perform pseudo-differentiation on the angular velocity of the rotating machine causes a phase delay. By applying the same low-pass filter as the low-pass filter for pseudo-differentiation to each of the torque of the motor-generator and the torque of the engine, it is possible to eliminate a phase difference between the torque sum and the product of the moment of inertia and rotational acceleration when calculating an estimated value of the load torque using the equation of motion. As a result, it is possible to appropriately calculate an estimated value of the load torque.

[0058] [Item 3] In the propulsion system of item 1 or 2, the controller may calculate a rotational acceleration by differentiating the angular velocity of the rotating machine, calculate an estimated value of the load torque by subtracting a value obtained by multiplying the rotational acceleration by the moment of inertia from the sum of the torque of the engine and the torque of the rotating machine, and extract a fluctuation component in the estimated value of the load torque by applying a high-pass filter to the estimated value of the load torque.

[0059] [Item 4] In the propulsion system of any one of items 1 to 3, the rotating machine may be a generator capable of generating electricity by using the driving force of the engine, and the controller may correct the torque command value so as to decrease the amount of power generated by the generator as the estimated value of the load torque increases, and to increase the amount of power generated by the generator as the estimated value of the load torque decreases.

[0060] [Item 5] In the propulsion system of any one of items 1 to 4, the rotating machine may be an electric motor capable of transmitting power to the propulsion propeller, and the controller may correct the torque command value so as to increase the output of the electric motor as the estimated value of the load torque increases and to decrease the output of the electric motor as the estimated value of the load torque decreases.

[0061] [Item 6] In the propulsion system of any one of items 1 to 5, the controller may correct the torque command value during steady navigation in which the thrust force command value is constant.

[0062] [Item 7] A control program for a ship according to another aspect of the present disclosure is a control program for a ship including an engine mechanically connected to a propulsion propeller, a rotating machine mechanically connected to the engine and capable of generating electricity using the driving force of the engine or transmitting power to the propulsion propeller, a power converter electrically connected to the rotating machine, and a controller that controls the engine and the power converter based on a propulsion force command value, wherein the control program causes the controller to acquire the torque of the engine, the torque of the rotating machine, the angular velocity of the rotating machine, and a predetermined moment of inertia converted into the rotating shaft of the rotating machine, calculate an estimated value of the load torque of the propulsion propeller using an equation of motion of a rotating shaft system of the rotating machine, generate a torque command value for the torque to be generated in the rotating machine from the propulsion force command value, and correct the torque command value so as to cancel out a fluctuation component in the estimated value of the load torque.

[0063] [Item 8] A method for controlling a ship according to another aspect of the present disclosure is a method for controlling a ship including an engine mechanically connected to a propulsion propeller, a rotating machine mechanically connected to the engine and capable of generating electricity using the driving force of the engine or transmitting power to the propulsion propeller, a power converter electrically connected to the rotating machine, and a controller that controls the engine and the power converter based on a thrust command value, the method comprising: acquiring the torque of the engine, the torque of the rotating machine, the angular velocity of the rotating machine, and a predetermined moment of inertia of the rotating machine converted into a rotating shaft; calculating an estimated value of the load torque of the propulsion propeller using an equation of motion of the rotating shaft system of the rotating machine; generating a torque command value for the torque to be generated in the rotating machine from the thrust command value; and correcting the torque command value so as to cancel out a fluctuation component in the estimated value of the load torque. [Explanation of symbols]

[0064] 1 Propulsion System 2 propellers 3 Engine 4. Motor generator 7 First power converter (power converter) 14 Controller 23 Differentiator 24, 27, 28 Low-pass filter 30 High Pass Filter

Claims

1. an engine mechanically connected to a propulsion propeller; a rotating machine mechanically connected to the engine and capable of generating electricity using the driving force of the engine or transmitting power to the propulsion propeller; a power converter electrically connected to the rotating machine; a controller that controls the engine and the power converter based on a thrust command value, The controller acquiring a torque of the engine, a torque of the rotating machine, an angular velocity of the rotating machine, and a predetermined moment of inertia of the rotating machine converted into a rotation axis; calculating an estimated value of load torque of the propulsion propeller using an equation of motion of a rotating shaft system of the rotary machine; generating a torque command value for a torque to be generated in the rotating machine from the thrust force command value; a propulsion system that corrects the torque command value so as to cancel out a fluctuation component in the estimated value of the load torque;

2. The controller applying a differentiator and a low-pass filter to the angular velocity of the rotating machine to pseudo-differentiate the angular velocity of the rotating machine and calculate a rotational acceleration; applying the same low-pass filter to the torque of the engine and the torque of the rotating machine as the low-pass filter applied to the angular velocity of the rotating machine; The propulsion system according to claim 1 , wherein the rotational acceleration, the torque of the engine after application of the low-pass filter, and the torque of the rotary machine are applied to the equation of motion.

3. The controller calculating a rotational acceleration by differentiating the angular velocity of the rotating machine; calculating an estimated value of the load torque by subtracting a value obtained by multiplying the rotational acceleration by the moment of inertia from the sum of the torque of the engine and the torque of the rotary machine; 3. The propulsion system according to claim 1, wherein a fluctuation component in the estimated value of the load torque is extracted by applying a high-pass filter to the estimated value of the load torque.

4. the rotating machine is a generator capable of generating electricity by utilizing the driving force of the engine, The controller 3. The propulsion system according to claim 1, wherein the torque command value is corrected so that the amount of power generated by the generator decreases as the estimated value of the load torque increases, and the amount of power generated by the generator increases as the estimated value of the load torque decreases.

5. the rotating machine is an electric motor capable of transmitting power to the propulsion propeller, The controller 3. The propulsion system according to claim 1, wherein the torque command value is corrected so that the output of the electric motor is increased as the estimated value of the load torque increases, and the output of the electric motor is decreased as the estimated value of the load torque decreases.

6. 3. The propulsion system according to claim 1, wherein the controller corrects the torque command value during steady sailing in which the thrust command value is constant.

7. an engine mechanically connected to a propulsion propeller; a rotating machine mechanically connected to the engine and capable of generating electricity using the driving force of the engine or transmitting power to the propulsion propeller; a power converter electrically connected to the rotating machine; a controller that controls the engine and the power converter based on a thrust command value, The control program causes the controller to: acquiring a torque of the engine, a torque of the rotating machine, an angular velocity of the rotating machine, and a predetermined moment of inertia of the rotating machine converted into a rotation axis; calculating an estimated value of the load torque of the propulsion propeller using an equation of motion of a rotating shaft system of the rotary machine; generating a torque command value for a torque to be generated in the rotating machine from the thrust force command value; a control program for correcting the torque command value so as to cancel out fluctuation components in the estimated value of the load torque;

8. an engine mechanically connected to a propulsion propeller; a rotating machine mechanically connected to the engine and capable of generating electricity using the driving force of the engine or transmitting power to the propulsion propeller; a power converter electrically connected to the rotating machine; a controller that controls the engine and the power converter based on a propulsive force command value, acquiring a torque of the engine, a torque of the rotating machine, an angular velocity of the rotating machine, and a predetermined moment of inertia of the rotating machine converted into a rotation axis; calculating an estimated value of load torque of the propulsion propeller using an equation of motion of a rotating shaft system of the rotary machine; generating a torque command value for a torque to be generated in the rotating machine from the thrust force command value; a control method for correcting the torque command value so as to cancel out a fluctuation component in the estimated value of the load torque;

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