JP5126751B2 - Marine electric propulsion system - Google Patents

Description

  The present invention relates to a marine electric propulsion system that drives a propeller (propulsion unit) by an AC motor that is speed-controlled by a power converter, and in particular, controls driving of the propulsion unit motor so that generator efficiency is optimized. The present invention relates to a marine electric propulsion system.

  As an electric propulsion system for ships, an AC generator is driven by a prime mover such as a diesel engine, the generated AC power is frequency-converted by a static power converter and supplied to the AC motor, and a propeller is driven by this AC motor. There is known an electric propulsion system for marine vessels that propels the marine vessel (for example, see Patent Document 1).

  FIG. 10 is a system configuration diagram in which a part of the circuit configuration disclosed in Patent Document 1 is omitted. In FIG. 10, reference numeral 1 denotes a three-phase AC generator (ACG; hereinafter simply referred to as “generator”), which is driven by a prime mover 2 such as a diesel engine to generate three-phase AC power and supply power to the inboard bus 3. It is connected. AVR is an automatic voltage regulator that controls the excitation of the generator so as to keep the output voltage of the generator (ACG) at a set value, and Gov is supplied to the prime mover 2 so as to keep the rotational speed of the prime mover 2 constant. It is a governor that controls fuel.

  The electric power supplied to the inboard bus 3 is supplied to a propulsion unit AC motor (ACM) via a static power conversion device 4 (generally referred to as an inverter in some cases) composed of a combination of a converter and an inverter. Hereinafter referred to simply as a propulsion device motor) and also to an inboard load (not shown).

  The converter and inverter of the static power converter 4 are constituted by, for example, a rectifying element such as a diode or a switching element such as an IGBT or a thyristor, and the AC power whose frequency is controlled based on a rotational speed command value given to the inverter Is output. The propulsion device motor 5 is driven by the AC power controlled at this frequency to drive the propeller 6.

  A rotational speed detector 7 detects an actual rotational speed 7s of the electric motor 5 for propulsion device. Reference numeral 8 denotes a rotation speed setting device that outputs a target rotation speed 8 s of the propulsion device motor 5 in conjunction with a position of a speed setting operation handle (not shown) provided in the steering chamber.

  Reference numeral 9 denotes a rotation speed controller, which compares the input target rotation speed 8s with the actual rotation speed 7s to obtain a deviation (8s-7s), and uses the rotation speed command value 9s generated based on the deviation as the stationary value. The rotational speed of the propulsion device motor 5 is controlled by providing the switching element of the inverter of the type power converter 4 as a gate signal, and the propulsion force by the propeller 6 is controlled.

  As described above, the rotational speed control method of the propulsion device motor 5 by the conventional marine electric propulsion system is a control method based on the rotational speed setting value 8s determined by the position of the speed setting operation handle provided in the steering chamber. Therefore, it was not a rotational speed control method in consideration of the operation efficiency of the generator 1.

JP 2007-62676 A

  In recent years, a so-called hybrid electric propulsion system in which a propeller is driven by each of a diesel engine (main engine) and an electric propulsion device that operates while suppressing fuel has become useful as an environmental measure and a fuel efficiency measure of a prime mover. Yes.

  In the case of a hybrid electric propulsion system, driving the propeller with an electric propulsion device can increase propulsion efficiency while suppressing fuel even if the propulsion motor does not have a rated output.

  However, in the prior art shown in FIG. 10, the propulsion device motor 5 is simply driven so as to achieve the target rotational speed regardless of the power generation efficiency of the generator driven by the main engine as described above. doing.

  For this reason, the generator output depends on the motor load for the propulsion device, and when the motor load for the propulsion device is large as in the case of heavy loads, depending on the size of the load on the ship, the output of the generator during operation alone will There is a case where a generator that is on standby is started without being able to cover the entire power consumption. In this case, since the load is shared by a plurality of generators, there is a problem that the load factor of the generator is lowered and fuel consumption is deteriorated. In addition, when the boat speed may be slow, navigation with a small number of operating generators is often required as a fuel efficiency measure.

  Therefore, in order to solve the above-described problems of the prior art, the present invention optimizes the generator efficiency from the known generator optimum output power, the detected output power of the generator, and the power consumption of the ship load. An object of the present invention is to provide a marine electric propulsion system that optimizes the efficiency of the generator by limiting the output of the electric motor for propulsion device to the load amount.

In order to achieve the above object, an invention according to claim 1 of the present invention includes a generator that is driven by a prime mover to supply AC power to an inboard bus, and an AC that is connected to the inboard bus and output from the generator. A power conversion device including an inverter that converts power to frequency and outputs AC power , a propulsion device motor driven by AC power output from the inverter of the power conversion device, and the propulsion device motor propeller and a rotation speed setter for setting a target rotational speed of the propulsion apparatus for a motor, a rotational speed detector for detecting an actual rotational speed of the propulsion apparatus for a motor, the set by the rotational speed setting unit goals The rotational speed and the actual rotational speed detected by the rotational speed detector are input, and the power converter is controlled so that the rotational speed of the propulsion device motor becomes the target rotational speed. A rotation speed controller for outputting a signal, the marine electric propulsion system comprising a ship load to which electric power is supplied from the inboard bus, a first power detector for detecting the output power of the generator, the a second power detector for detecting the power consumption of the inboard load, wherein the first output power of the detected generator by the power detector, the power consumption and advance of detected inboard load the second power detector When the optimum output power of the generator being measured is input and the output power of the generator exceeds the optimum output power of the generator, the upper limit value of the power used in the propulsion device motor is set to the generator the rotational speed power limit signal for limiting the control signal output to the power converter power consumption from the rotational speed controller so that the power values are calculated by subtracting from the optimum output power inboard load and output to the controller, calling When the output power of the machine does not exceed the optimum output power of the generator, a power limit value setter which does not give limit to the control signal outputted from the rotational speed controller to the power converter, further comprising a Features.

  According to the electric propulsion system for a ship of the present invention, it is possible to limit the output of the motor to a load amount at which the generator efficiency is optimal without depending on the load situation on the ship, and the fuel efficiency (efficiency) of the power generation system (motor + generator) ) Can be provided.

1 is a system configuration diagram of a marine electric propulsion system according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating an example of a rotation speed controller according to the first embodiment. FIG. 2 is a block diagram illustrating an example of a power limit value setting device according to the first embodiment. Action | operation explanatory drawing of the electric power limit value setting device of FIG. The characteristic view which shows the relationship between the output (electric motor output) of a propeller, and rotational speed. 4 is a time chart for explaining the operation of the first embodiment. The system block diagram of the electric propulsion system for ships which concerns on Embodiment 2 of this invention. FIG. 5 is a block diagram illustrating an example of a rotation speed controller according to a second embodiment. The figure which shows the relationship between the output torque (output torque of an electric motor) of a propeller, and rotational speed. The system block diagram of the conventional electric propulsion system for ships.

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, the same parts as those shown in FIG. 10 are denoted by the same reference numerals, and redundant description will be omitted as appropriate.

[Embodiment 1]
(Constitution)
FIG. 1 is a system configuration diagram of a marine electric propulsion system according to Embodiment 1 of the present invention, FIG. 2 is a block diagram showing an example of a rotation speed controller of Embodiment 1, and FIG. 3 is Embodiment 1. 4 is a block diagram showing an example of the power limit value setting device, FIG. 4 is an operation explanatory diagram of the power limit value setting device, and FIG. 5 is a characteristic diagram showing the relationship between the output (motor output) of the propeller and the rotation speed.

  First, in the system configuration diagram of FIG. 1, the control elements from the generator (ACG) 1 to the rotation speed setting device 8 are the same control elements as in the prior art shown in FIG. 10. The rotational speed controller 9A is obtained by adding one control element to the rotational speed controller 9 shown in FIG. 10, and the control elements 11 to 18 are control elements added to the first embodiment. .

  9A is a rotational speed controller obtained by adding a control element to the rotational speed controller 9 of the prior art, 11 is an instrument transformer for detecting the output voltage of the generator (ACG) 1, and 12 is a generator (ACG) 1 A current transformer 13 for detecting the output current of the power generator 13 is an electric power for detecting the generator output power Pg by inputting the generator output voltage and the output current detected by the instrument transformer 11 and the current transformer 12. It is a detector and is referred to as a first power detector for convenience.

  Reference numeral 14 denotes an inboard load connected to the inboard bus 3, and the electric power PL consumed here is obtained by the electric power detector 17 based on the voltage and current detected by the instrument transformer 15 and the instrument current transformer 16. It is to be detected. For convenience, the power detector 17 is referred to as a second power detector.

  18 receives the output power Pg of the first power detector 13, the output power PL of the second power detector 17, and the generator optimum output Pgr which is a known fixed value measured in advance. It is a power limit value setter that calculates and outputs a power limit value signal 18s.

Next, the rotation speed controller 9A will be described in detail with reference to FIG.
Rotational speed controller 9A, similar to the common rotational speed controller, and generates an adder _9-1 for calculating a deviation between the command value and the feedback signal, a control signal to the error amplifier based on the difference rotational together and a speed command adjusting unit 9 _-2, is constructed in front of a newly adding unit 9 _-1 to provide a rotational speed setting adjuster 9 _-3.

The newly provided rotation speed setting controller _9-3 includes an arbitrary rotation speed N of the propeller 6 described in FIG. 5 described later, and a propulsion device motor 5 that can output at the rotation speed N. The relational characteristic with the electric power Pm is obtained in advance by an experiment or the like, and a power limit value signal 18s output from a power limit value setter 18 described later and a speed command value 8s from the rotation speed setter 8 are input. The control element is configured to output a rotation speed value corresponding to the power limit value signal 18s as a rotation speed command value _9-3s .

Adding unit 9 provided in the next stage _-1 calculates a deviation between the feedback signal 7s from the rotational speed detector 7 and the rotational speed command value 9 _-3S, stationary through the rotational speed command adjusting unit 9 _-2 A control signal 9As is output to the inverter of the power conversion device 4.

Next, the power limit value setter 18 will be described in detail with reference to FIG.
First, a "generator output power Pg" detected by the first power detector 13, known to have been previously determined as "generator optimum output Pgr" is calculated by the first adder 18 _-1 , Deviation ΔP1 is output. Here, the generator optimum output Pgr indicates the generator output power when the generator efficiency η is the highest among the generator efficiency η (η; generator output / motor input). This generator efficiency η can be measured during a unit test of the generator (ACG) 1 or the like.

The first adder 18 _-1, generator output power Pg outputs the deviation ΔP1 plus (+) when it exceeds the generator optimum output Pgr (Pg> Pgr), generator output power Pg is the generator When the optimum output Pgr is not exceeded (Pg ≦ Pgr), a minus (−) deviation ΔP1 is output.

Or is a - generator output power deviation detector 18 _-2 enter the deviation ΔP1 outputted from the first adder 18 _-1, the polarity of the deviation is positive (+) or a minus () It determines, and outputs a switching signal to the power limit value signal switching device 18 _-5 in accordance with the determination result. About how the operation power limit value signal switching device 18 _-5 by the switching signal will be described later.

Generator optimum output Pgr described above is inputted operation with inboard load power PL detected by the second power detector 17 to the second adder 18 _-3. In the second adder 18 _-3, a deviation ΔP2 corresponding to the surplus power (Pgr-PL) when the subtracting inboard load power PL from the generator optimum output Pgr. This surplus power is an upper limit value of power used in the propulsion device motor 5, that is, a power limit value (Plim = Pgr−PL).

The deviation ΔP2 corresponding to the surplus power output from the second adder 18 _-3 is input to the unit conversion calculator 18 _-4 and converted from kw to%, and then the power limit value signal switch 18 Input to _-5 .

The power limit value signal switching device 18 _-5 is provided with a change-over switch 18 _-50 inside as shown in Figure 4 a detailed configuration from the generator output power deviation detector 18 _-2 positive (+) When the switching signal is input, the signal output from the unit conversion computing unit _18-4 is selected by connecting the switching contact to the (+) side fixed contact, and is output to the control element of the next stage. Conversely, when a minus (−) switching signal is input from the generator output power deviation detector 18 _-2 , the limit value setter 18 ₋₆ is connected by connecting the switching contact to the (−) side fixed contact. “Limit value setting 100%” is selected from the above and output to the control element in the next stage.

18 _-7 is a filter circuit, is configured to gradually transform and outputting a change in the input signal from the power limiting value signal switching device 18 _-5 as a general first-order lag element. The output signal of the filter circuit 18 _-7 is power limit signal 18s shown in FIG. 1, it is input to the rotational speed controller 9A.

FIG. 5 is a diagram showing the relationship between the output power Pm and the rotational speed N of the propeller 6, in other words, the propulsion device motor 5. P ₁₀₀ is the power at the rated load, the Plim power limit, N ₁₀₀ is rated speed, Nlim is the rotational speed limit corresponding to Plim.

(Function)
Next, the operation of the first embodiment will be described.
In the system configuration diagram of FIG. 1, the output power Pg of the generator 1 driven by the prime mover 2 is used as a power source for the propulsion device motor 5 and the ship load 14 that are driven by the stationary power converter 4 through the ship bus 3. used.

The “generator output power Pg” of the generator 1 detected by the first power detector 13 based on the voltage and current detected by the instrument transformer 11 and the instrument current transformer 12 is a power limit value setting device. 18, on the other hand, is consumed by the inboard load 14 detected by the second power detector 17 based on the voltage and current detected by the instrument transformer 15 and the instrument current transformer 16. “Power PL” is input to the power limit value setting unit 18. In addition to these detected power values, “power generator optimum output Pgr”, which is a fixed value measured in advance, is input to the power limit value setter 18.

The “generator optimum output Pgr” and the “inboard load power consumption PL” are calculated by the second adder 18 _-3 , and a calculator for converting the power value (Pgr−PL) of the difference between the units. 18 inputs through _-4 power limit value signal switching device 18 _-5.

Meanwhile, the "generator output power Pg" and "generator optimum output Pgr" is calculated by the first adder 18 _-1, further generator output power deviation detector 18 'generator output power Pg at _-2 ”Exceeds the“ generator optimum output Pgr ”(Pg> Pgr) or not (Pg ≦ Pgr).

When the generator output power deviation detector 18 _-2 "generator output power Pg" is judged to exceed the "generator optimum output Pgr" is switching contact of the power limit value signal switching device 18 ₅ By connecting to the fixed contact on the plus (+) side in FIG. 4, the surplus power (Pgr−PL) equivalent signal output from the second adder 18 ₋₃ input through the unit conversion calculator 18 ₋₄ is obtained. select output, and outputs the rotational speed controller 9A through the filter circuit 18 _-7 as the power limit value signal 18s. In this case, Plim = Pgr−PL.

However, when it is determined by the generator output power deviation detector 18 _-2 that “generator output power Pg” does not exceed “generator optimum output Pgr” (Pg ≦ Pgr), the power limit value signal switching is performed. vessel 18 ₅ switching contact negatively 4 (-) by connection changeover to the fixed contact side select "limit value setting 100%" of the limit value setter 18 _-6, the filter circuit 18 _-7 Then, it is output to the rotational speed controller 9A as a power limit value signal 18s.

The rotational speed controller 9A, the power limit value signal 18s from the power limit value controller 18 to the rotational speed setting adjuster 9 _-3, the speed command value 8s from the rotational speed setting unit 8 inputs, respectively, in FIG. 2 Te, determine the rotational speed command value 9 _-3S rotational speed value corresponding to the power limit value signal 18s, based on a deviation between the rotational speed signal 7s detected as the rotation speed command value 9 _-3S at a rotational speed detector 7 The rotational speed command value 9As generated in this way is applied as a gate signal to the switching element of the inverter of the static power converter 4, thereby controlling the rotational speed of the propulsion device motor 5 and controlling the propulsive force by the propeller 6. To do.

  Therefore, when it is determined that “generator output power Pg” does not exceed “generator optimum output Pgr” (Pg ≦ Pgr), the rotational speed controller 9A is not limited by the power limit value setter 18. The inverter switching element of the static power converter 4 is gate-controlled to control the rotational speed of the propulsion device motor 5, but the “generator output power Pg” exceeds the “generator optimum output Pgr” ( When it is determined that Pg> Pgr), the inverter of the static power converter 4 controls the rotation speed of the propulsion device motor 5 so as not to exceed the limited power (Plim = Pgr−PL). In this way, the power limit signal 18s is calculated so that the generator 1 has optimum efficiency.

FIG. 6 is a time chart for explaining the operation of the marine electric propulsion system according to the first embodiment.
In FIG. 6, the generator 1 is started at time t1 and power supply to the inboard load 14 is started, and the generator output power Pg becomes large enough to cover the inboard load power consumption PL. Since the inboard power is supplied by the generator output power, there is no other load, and Pg = PL is established if each device loss is ignored.

  Next, when the “speed setting operation handle” provided in the wheelhouse is operated to the “acceleration (forward direction and reverse direction)” side at time t3, the target rotational speed 8s of the rotational speed setting device 8 increases. The propulsion load power (Pm) supplied to the propulsion motor 5 through the inverter of the stationary power converter 4 increases. Along with this, the governor of the prime mover 2 operates and the generator output power Pg further increases. At this time, if the loss of each device is ignored, Pg = PL + Pm is established.

  Since Pg ≦ Pgr between times t3 and t4, there is no power limitation on the propulsion motor 5, and the rotation speed of the propulsion motor 5 is determined by the output signal of the rotation speed setter 8 and the output signal of the rotation speed detector 7. The command value is obtained by feedback control.

  Thereafter, at time t4, since the generator output power Pg reaches the generator optimum output Pgr, the power limit value setter 18 limits the output of the stationary power converter 4 and supplies it to the propulsion device motor 5. Limit propulsion load power (Pm). The power output restriction to the propulsion device motor 5 continues until time t5 when the generator output power Pg is lower than the generator optimum output Pgr. Since the output to the propulsion device motor 5 is limited between the times t4 and t5 as described above, the rotational speed of the propulsion device motor 5 decreases and the propulsive force of the propeller 6 decreases, but the generator 1 Operated with maximum efficiency.

  Since the power consumption of the inboard load 14 has decreased after time t5, the governor of the prime mover 2 operates to lower the generator output power Pg. At this time, since the restriction on the propulsion load power (Pm) is released, Pm changes depending on the propulsion load.

  As is clear from the above description, the upper limit electric energy used by the propulsion device motor 5 is obtained by Plim = Pgr−PL. However, when a plurality of generators 1 are operating, Pgr = What is necessary is just to calculate as Pgr1 + Pgr2 + ... + PgrN. Here, Pgr1 is the output power at the optimal efficiency of the first generator, Pgr2 is the output power at the optimal efficiency of the second generator, and PgrN is the output power at the optimal efficiency of the Nth generator.

Even when Plim <Pg, when the output signal of the rotational speed detector 7 is equal to or less than the rotational speed Nlim for limiting the propeller load characteristic (P∝N ³ ) to Plim as shown in FIG. In the same manner as described above, feedback control is performed by the output signal of the rotation speed setting device 8 and the output signal of the rotation speed detector 7.

  Further, when Plim <Pg and the output signal of the rotational speed setting device 8 is larger than Nlim, the target rotational speed is limited to Nlim, and feedback control is performed by Nlim and the output signal of the rotational speed detector 7.

(effect)
As described above, according to the first embodiment, the generator optimum output Pgr measured in advance and the generator output power Pg measured during operation are used as the generator output power deviation detector 18 _-2. in when the generator output power Pg compared is determined to exceed the generator optimum output Pgr (Pg> Pgr) is the power limit value signal switching device 18 _5, inboard load from the generator optimum output Pgr The propulsion device motor 5 is operated so that the power limit value (Plim = Pgr−PL) obtained by subtracting the power consumption PL becomes the upper limit value of the power Pm used in the propulsion device motor 5. The generator (ACG) 1 can be operated with the optimum operating efficiency η.

[Embodiment 2]
Hereinafter, with reference to FIG. 7 thru | or FIG. 9, the electric propulsion system for ships which concerns on Embodiment 2 of this invention is demonstrated.

  FIG. 7 is a system configuration diagram of a marine electric propulsion system according to Embodiment 2 of the present invention, FIG. 8 is a block diagram showing an example of a rotational speed controller of Embodiment 2, and FIG. 9 is output torque of a propeller. It is a characteristic view which shows the relationship between (output torque of an electric motor) and rotational speed.

  The second embodiment is a system in which the speed of the propulsion device motor 5 is controlled by the inverter of the static power converter 4 as in the first embodiment, and the power consumption of the propulsion device motor is limited by the static power. This is realized by giving a torque limit to the conversion device 4.

In FIG. 7, 9B is a rotating speed controller, similar to the rotational speed controller 9A of FIG. 2 as detailed in FIG. 8, an adder 9 _-1 for calculating a deviation between the command value and the feedback signal, together and a rotational speed command adjusting unit 9 _-2 generates a control signal based on the deviation, it is constructed in front of a newly adding unit 9 _-1 to provide a second rotational speed setting adjuster 9 _-4 Yes.

The newly provided rotational speed setting controller _9-4 includes an arbitrary rotational speed N of the propeller 6 described in FIG. 9 to be described later, and a propulsion device motor 5 that can output at the rotational speed N. The relational characteristic with the torque T is obtained in advance by an experiment or the like, and a torque limit value 20s (Tlim) from a torque limit value setter 20 described later and a speed command value 8s from the rotation speed setter 8 are input. The control element is configured to output a rotation speed value corresponding to the torque limit value Tlim as a rotation speed command value 9 _{-4 s} .

FIG. 9 is a diagram showing the relationship between the output torque of the propeller (output torque of the electric motor) and the rotation speed. The description of the same symbols as those described in FIG. 5 is omitted. T ₁₀₀ is the torque at the rated load, is Tlim a torque limiting.

Adding unit 9 _-1 calculates a deviation between the feedback signal 7s from the rotational speed detector 7 and the rotational speed command value 9 _-4S, inverter static power converter 4 through the rotational speed command adjusting unit 9 _-2 Control signal 9Bs.

Reference numeral 20 denotes a torque limit value setter, which determines a torque value to be limited in advance.
In the second embodiment, the output signal 20s output from the torque limit value setting unit 20, the output signal 8s from the rotation speed setting unit 8, and the output signal 7s from the rotation speed detector 7 are used as the rotation speed controller 9B. The rotational speed command value 9 _{-4 s} obtained from the set value 20 s of the torque limit value setter 20 and the output signal 8 s of the rotational speed setter 8 by the rotational speed setting controller 9 _-4 and the rotational speed detector 7, feedback control is performed using the actual rotational speed signal 7 s, the propulsion device motor 5 is driven by the stationary power converter 4, and the propeller 6 is rotated. At this time, the rotation speed controller 9B limits the target rotation speed in order to limit the torque from the relationship between the propeller torque and the rotation speed (T∝N ² ) as shown in FIG.

It should be noted that the torque limit value Tlim may be configured such that a plurality of types can be switched.
Since the switching of the torque limit value is a fixed value, when there are a plurality of Pg fluctuation patterns (load fluctuation patterns) (for example, there are specific fluctuations such as operation of an auxiliary motor or refrigerator), a plurality of types are switched. Therefore, it can be operated to achieve the optimum generator efficiency.

  As described above, according to the second embodiment, instead of detecting the power of the generator and the load as in the first embodiment, the torque limit is set by the torque limit value setting unit 20, thereby the first embodiment. Similarly to the above, it is possible to limit the power consumed by the electric motor for propulsion device.

DESCRIPTION OF SYMBOLS 1 ... Generator, 2 ... Prime mover, 3 ... Inboard bus, 4 ... Static power converter, 5 ... Electric motor for propulsion devices, 6 ... Propeller, 7 ... Rotational speed detector, 8 ... Rotational speed setter, 9A, 9B ... rotational speed controller, 11, 15 ... transformer, 12, 16 ... transformer, 13 and 17 ... power detector, 18 ... power limit value setter, 18 _-1, 18 _-3 ... adder, 18 _{- 4} ... generator output power deviation detector 18 _-5 ... power restriction value switching interrupter 18 _-6 ... limit of 100% setter 18 _-7 ... filter circuit, 20 ... torque limit value setter.

Claims (2)

A generator driven by a prime mover to supply alternating current power to the inboard bus;
A power converter comprising an inverter connected to the inboard bus and output from the generator to convert the frequency of the AC power and output the AC power ;
A propulsion device motor driven by alternating current power output from the inverter of the power converter;
A propeller driven by the propulsion device motor;
And rotational speed setting unit for setting a target rotational speed of the propulsion apparatus for a motor,
A rotational speed detector for detecting an actual rotational speed of the electric motor for propulsion device;
Input the target rotational speed set by the rotational speed setter and the actual rotational speed detected by the rotational speed detector, and control the power converter so that the rotational speed of the electric motor for propulsion device becomes the target rotational speed A rotation speed controller that outputs a signal;
In the ship electric propulsion system provided with an inboard load supplied with electric power from the inboard bus,
A first power detector for detecting the output power of the generator;
A second power detector for detecting power consumption of the ship load;
Enter the first output power of the detected generator by the power detector, the optimum output power of the power consumption and advance being measured the generator of the detected inboard load the second power detector, power When the output power of the machine exceeds the optimum output power of the generator, the upper limit value of the power used by the propulsion device motor is obtained by subtracting the power consumption of the ship load from the optimum output power of the generator. the power limit value signal for limiting the control signal the output from the rotation speed controller to the power converter such that the other power value is output to the rotational speed controller, the optimum output power of the generator of the generator When the output power is not exceeded, a power limit value setter that does not limit the control signal output from the rotational speed controller to the power converter ,
Electric propulsion system for vessels, comprising the. The power limit value setter is a generator output power deviation detector that determines whether or not the output power of the generator exceeds the optimum output power of the generator;
If the output power of the generator by the generator output power deviation detector is determined to exceed the optimal output power of the generator, that is determined by subtracting the power consumption of the inboard load from the optimal output power of the generator select output power limit value signal based on the power value, when the output power of the generator is determined not to exceed the optimal output power of the generator by the generator output power deviation detector, without limiting value signal A power limit value signal switch that outputs as a power limit value signal to the rotational speed controller via a filter circuit ;
The marine electric propulsion system according to claim 1, comprising:

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