JP2024071755A - Electric Propulsion Unit - Google Patents

Abstract

An electric propulsion device capable of suppressing power fluctuations in an onboard busbar system is provided.
[Solution] The electric propulsion device of the present invention includes a speed controller that generates a first torque reference based on the difference between a speed reference between a rotational speed detected by a speed detector and a rotational speed set by a speed setter, a generation circuit that generates a second torque reference that fluctuates less than the first torque reference generated by the speed controller in accordance with fluctuations in the rotational speed detected by the speed detector, a switching circuit that exclusively switches between the first torque reference generated by the speed controller and the second torque reference generated by the generation circuit, a magnetic flux reference calculator and a magnetization component current calculator that generate a magnetic flux reference based on the first torque reference or the second torque reference, a current controller that amplifies the difference between the current reference signal generated by the speed controller and the magnetization component current calculator and the detected current of a power converter, a current transformer that detects the current of the power converter, and a coordinate converter for performing vector control of the power converter.
[Selected Figure] Figure 1

Description

The present invention relates to an electric propulsion device for an onboard system.

Figure 3 is a diagram showing the configuration of a conventional electric propulsion device control method using a vector control inverter, as shown in Non-Patent Document 1.

In FIG. 3, 1 is an electric propulsion device, which is a system that includes 3 to 14 described below, 2 is a speed setter, 3 is a speed controller, 4 is a magnetic flux reference calculator, 5 is a magnetization component current calculator, 6 and 7 are current controllers, 8 is a phase calculator, 9 and 10 are coordinate converters, 11 is a power converter, 12 is a current transformer, 13 is a propulsion motor, 14 is a speed detector, 15 is a propulsion propeller, 16 is a power converter circuit breaker, 17 is a circuit breaker for AC power sources such as diesel generators, 18 is an AC power source such as a diesel generator, and 19 is an onboard busbar system.

The normal operation of the conventional electric propulsion device 1 shown in Figure 3 will be described.

The onboard bus system 19 is configured by connecting an AC power source 18 such as a diesel generator via a circuit breaker 17. The onboard bus system 19 is connected to the power converter 11 of the electric propulsion device 1 via a circuit breaker 16.

The power converter 11 supplies power from the onboard bus system 19 to the propulsion motor (PM) 13. The propulsion motor 13 is the power source for the propulsion propeller 15, and drives the propulsion propeller 15 with the power supplied from the power converter 11.

The speed setter 2 sets the rotation speed of the propulsion motor 13 to generate a speed reference ω ^* . The speed controller 3 amplifies the error between the speed reference ω ^* generated by the speed setter 2 and the rotation speed (actual speed ω) of the propulsion motor 13 detected by a speed detector (PG) 14, and generates a torque reference τ ^* .

Furthermore, the magnetic flux reference calculator 4 calculates a magnetic flux reference Φ2 ^* based on the actual speed ω detected by the speed detector 14, and outputs the calculated magnetic flux reference Φ2* to the magnetization component current calculator 5. The magnetization component current calculator 5 generates a magnetic flux reference Id ^* based on the magnetic flux reference Φ2 ^* from the magnetic flux reference calculator 4.

A divider 20 generates a torque component current reference Iq ^* according to the aforementioned torque reference τ ^* and flux reference Φ2 ^* .

The current transformer 12 detects the actual current of the power converter 11. The coordinate converter 9 performs coordinate conversion based on the actual current detected by the current transformer 12 and the phase θ1 determined by the phase calculator 8 based on the rotation speed (actual speed ω), and outputs a torque component current feedback Iq and a magnetization component current feedback Id. The torque component current feedback Iq is differentially amplified with the torque component current reference Iq ^* described above, and is supplied to a coordinate converter 10 for vector control via a current controller 7. The magnetization component current feedback Id is differentially amplified with the magnetization component current reference Id ^* , and is supplied to the coordinate converter 10 via a current controller 6. The coordinate converter 10 generates power converter primary voltage references (Vu ^* , Vv ^* , Vw ^* ) based on inputs from the current controllers 6 and 7, and operates the propulsion motor 13.

The Institute of Electrical Engineers, "Electrical Engineering Handbook", 6th edition, Vol. 21, Drive Systems, Chapter 4, Variable Speed Drives for Induction Machines, P886, Figure 43

In the conventional electric propulsion device 1 shown in FIG. 3, a torque reference is calculated by amplifying the error between the speed reference ω ^* of the speed setter 2 and the actual speed ω. However, the gain of the speed controller 2 is generally large, and even if the actual speed fluctuation is small, the torque reference τ ^* changes sharply as a result of the calculation.

In particular, in bad weather, constant load fluctuations in the electric propulsion device 1 cause fluctuations in the actual speed ω, which leads to abrupt fluctuations in the torque reference τ ^* . The fluctuations in the torque reference τ ^* contribute to power fluctuations in the power converter 11 and the propulsion motor 13, but because the voltage and current of the power converter 11 are supplied from the onboard bus system 19, the onboard bus system power 19 will fluctuate abruptly as a result, which has the problem of adversely affecting the AC power source 18 such as a diesel generator that supplies power to the onboard bus system 19, and power supply equipment.

The present invention aims to provide an electric propulsion device that can suppress power fluctuations in the ship's busbar system.

In order to achieve the above object, the electric propulsion device according to the invention described in claim 1 includes a power converter connected to an inboard bus system powered by an AC power source and driving a propulsion motor to which a propeller is connected, a speed setter that sets the rotational speed of the propulsion motor, a speed detector that detects the rotational speed of the propulsion motor, a phase calculator that determines a phase based on the rotational speed detected by the speed detector, a speed controller that generates a first torque reference based on the difference between the speed reference of the rotational speed detected by the speed detector and the rotational speed set by the speed setter, and a speed controller that controls the speed controller in response to fluctuations in the rotational speed detected by the speed detector. The device includes a generation circuit that generates a second torque reference that fluctuates less than the first torque reference generated by the speed controller, a switching circuit that exclusively switches between the first torque reference generated by the speed controller and the second torque reference generated by the generation circuit, a magnetic flux reference calculator and a magnetization component current calculator that generate a magnetic flux reference based on the first torque reference or the second torque reference, a current controller that amplifies the difference between the current reference signal generated by the speed controller and the magnetization component current calculator and the detected current of the power converter, a current transformer that detects the current of the power converter, and a coordinate converter for performing vector control of the power converter.

The electric propulsion device according to the invention described in claim 2 is the electric propulsion device described in claim 1, in which the generation circuit includes a cube calculator that cubes the speed reference of the rotation speed set by the speed setter, and a circuit that calculates the second torque reference based on the calculation result of the cube calculator and the rotation speed detected by the speed detector.

The electric propulsion device according to the invention described in claim 3 is the electric propulsion device described in claim 1, in which the generation circuit is provided with a torque reference table that determines the second torque reference according to the rotational speed set by the speed setter, in which the second torque reference corresponds to each of the speed references of a plurality of different rotational speeds set by the speed setter and fluctuates less than the first torque reference generated by the speed controller according to the speed reference of the rotational speed set by the speed setter.

The electric propulsion device of the present invention prevents sudden fluctuations in the torque reference, and as a result, fluctuations in the onboard bus system power can be suppressed.

1 is a block diagram showing an example of the configuration of an electric propulsion device according to a first embodiment of the present invention. FIG. 6 is a block diagram showing an example of the configuration of an electric propulsion device according to a second embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of a conventional electric propulsion device.

The following describes an embodiment of the present invention with reference to the drawings.

First Embodiment
(composition)
FIG. 1 is a diagram showing an example of the configuration of an electric propulsion device according to a first embodiment of the present invention.

In FIG. 1, 100 is an electric propulsion device, which is a system including 3 to 14 and 21 to 23 described below, 2 is a speed setter, 3 is a speed controller, 4 is a magnetic flux reference calculator, 5 is a magnetization component current calculator, 6 and 7 are current controllers, 8 is a phase calculator, 9 and 10 are coordinate converters, 11 is a power converter, 12 is a current transformer, 13 is a propulsion motor, 14 is a speed detector, 15 is a propulsion propeller, 16 is a power converter circuit breaker, 17 is an AC power supply circuit breaker for a diesel generator or the like, and 18 is a diesel 19 is an AC power source such as a generator, 20 is a divider, 21 is a switch for selecting the torque reference (first torque reference) calculated by the speed controller 3, 22 is a cube calculator that cubes the speed setting signal from the speed setting device 2, 23 is a divider that calculates the torque reference (second torque reference) from the result of the cube calculation by the cube calculator 22 and the actual speed ω, and 24 is a switch for selecting the torque reference (second torque reference) calculated by the divider 24.

In FIG. 1, the same components as those in the electric propulsion device 1 shown in FIG. 3 are designated by the same reference numerals and will not be described.
(Action)
Figure 1 shows an electric propulsion device 1 having a configuration similar to that shown in Figure 3, to which a generation circuit is added that generates a torque reference τ ^* (second torque reference) that fluctuates less than the torque reference τ ^* (first torque reference) generated by the speed controller 3 in response to fluctuations in the rotational speed (actual speed ω) detected by the speed detector 14, and a switching circuit that exclusively switches between the torque reference τ ^* (first torque reference) generated by the speed controller 3 and the torque reference τ ^* (second torque reference) generated by the generation circuit.

In the first embodiment, a generating circuit that generates a torque reference τ ^* (second torque reference) is composed of a cube calculator 22 that cubes the speed reference ω ^* of the rotation speed set by the speed setter 2, and a divider 23 that calculates the second torque reference based on the calculation result of the cube calculator 22 and the rotation speed (actual speed ω) detected by the speed detector 14. In addition, switches 21 and 24 are provided as a switching circuit.

In the conventional technology, the difference between the speed reference ω ^* by the speed setter 2 and the actual speed ω by the speed detector 14 is error-amplified by the speed controller 3 to generate the torque reference τ ^* . However, the speed controller 3 generally has a large gain, and the torque reference fluctuates sharply as a calculation result even when the actual speed fluctuation is small.

Here, it is known that the load characteristic (power-speed characteristic) of the propulsion propeller 15 is that power is proportional to the cube of the speed, and the relationship between the speed ω, torque τ, and power P is given by τ=P/ω. Therefore, by determining the torque reference τ* by dividing the power reference value P ^* calculated by the cube calculator 23 from the speed reference ω ^* of the speed setter 2 by the actual speed ω from the speed detector 14 by the divider ²⁴ , it is possible to generate a torque reference that does not fluctuate sharply as long as the speed reference ω ^* does not change.

When performing an operation that requires suppressing torque reference fluctuations, for example when the actual speed ω fluctuates due to constant load fluctuations on the electric propulsion device 1 during bad weather, the switches 21 and 24 close the switch 24 and open the switch 21. In other words, instead of the torque reference τ ^* (first torque reference) generated by the speed controller 3, the torque reference τ ^* (second torque reference) generated by the generation circuit (cube calculator 23, divider 23) is switched to.
(effect)
According to the first embodiment, by providing a generation circuit (cube calculator 23, divider 23) that suppresses torque reference fluctuations even when the actual speed ω fluctuates, and switches 21, 24 that switch from the torque reference τ ^* (first torque reference) generated by the speed controller 3 to the torque reference τ ^* (second torque reference) generated by the generation circuit, it is possible to control the power converter 11 using a torque reference that does not fluctuate suddenly, and as a result, it is possible to suppress power fluctuations in the power converter 11, the propulsion motor 13 and the onboard busbar system 19.
Second Embodiment
(composition)
FIG. 2 is a diagram showing an example of the configuration of an electric propulsion device according to a second embodiment of the present invention.

In FIG. 2, 101 is an electric propulsion device, which is a system including 3 to 14 and 21, 25, and 26 described below; 2 is a speed setter; 3 is a speed controller; 4 is a magnetic flux reference calculator; 5 is a magnetization component current calculator; 6 and 7 are current controllers; 8 is a phase calculator; 9 and 10 are coordinate converters; 11 is a power converter; 12 is a current transformer; 13 is a propulsion motor; 14 is a speed detector; 15 is a propulsion propeller; 16 is a power converter circuit breaker; 17 is a circuit breaker for an AC power source such as a diesel generator; 18 is an AC power source such as a diesel generator; 19 is an onboard bus system; 20 is a divider; 21 is a switch for selecting the torque reference (first torque reference) calculated by the speed controller 3; 25 is a switch for selecting the torque reference table 26; and 26 is a torque reference table.

In FIG. 2, the same components as those in the electric propulsion device 1 shown in FIG. 3 are designated by the same reference numerals and will not be described.
(Action)
Figure 2 shows an electric propulsion device 1 according to the conventional embodiment shown in Figure 3 , with the addition of a generation circuit that generates a torque reference τ ^* (second torque reference) that fluctuates less than the torque reference τ* (first torque reference) generated by the speed controller 3 in response to fluctuations in the rotational speed (actual speed ω) detected by the speed detector 14, and a switching circuit that exclusively switches between the torque reference τ ^* (first torque reference) generated by the speed controller 3 and the torque reference τ ^* (second torque reference) generated by the generation circuit, similar to the electric propulsion device 100 in the first embodiment ^shown in Figure 1.

In the second embodiment, a generating circuit for generating the torque reference τ ^* (second torque reference) is configured by a torque reference table 26. The torque reference table 26 is set with a torque reference τ ^* (second torque reference) corresponding to each of a plurality of different rotational speeds set by the speed setter 2, which fluctuates less than the torque reference τ ^* (first torque reference) generated by the speed controller 3 according to the speed reference ω ^* of the rotational speed set by the speed setter 2. The torque reference table 26 determines and outputs the torque reference τ ^* (second torque reference) corresponding to the speed reference ω ^* of the rotational speed set by the speed setter 2. In addition ^, switches 21 and 25 are provided as a switching circuit.
In the conventional technology, the difference between the speed reference ω ^* by the speed setter 2 and the actual speed ω by the speed detector 14 is error-amplified by the speed controller 3 to generate the torque reference τ ^* . However, the speed controller 3 generally has a large gain, and the torque reference fluctuates sharply as a calculation result even when the actual speed fluctuation is small.

Here, by determining the torque reference τ ^* corresponding to the speed reference ω ^* of the speed setter 2 using the torque reference table 26, it is possible to generate a torque reference that does not change sharply as long as the speed reference ω ^* does not change.

When performing an operation that requires suppressing torque reference fluctuations, for example when the actual speed ω fluctuates due to constant load fluctuations in the electric propulsion device 1 during bad weather, the switches 21 and 25 close the switch 25 and open the switch 21. In other words, instead of the torque reference τ ^* (first torque reference) generated by the speed controller 3, the torque reference τ ^* (second torque reference) generated by the generation circuit (torque reference table 26) is used.
(effect)
According to the second embodiment, although power fluctuates depending on the actual speed ω, the rate of change of the actual speed ω is generally smaller than the rate of change of the output (torque reference τ ^* (first torque reference)) of the speed controller 3. Therefore, by providing a torque reference table 26 that outputs a torque reference τ ^* (second torque reference) corresponding to the speed reference ω ^* of the rotational speed set in the speed setter 2, and a switching circuit (switches 21, 25) that switches from the torque reference τ ^* (first torque reference) generated by the speed controller 3 to the torque reference τ ^* (second torque reference) generated by the generation circuit, the power converter 11 can be controlled using a torque reference that does not fluctuate suddenly, and as a result, power fluctuations in the power converter 11, the propulsion motor 13 and the onboard busbar system 19 can be suppressed.

The present invention is not limited to the above-described embodiments as they are, and in the implementation stage, the components can be modified and embodied without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

Reference Signs List 1, 100, 101... Electric propulsion device 2... Speed setter 3... Speed controller 4... Magnetic flux reference calculator 5... Magnetization component current calculator 6... Current controller 7... Current controller 8... Phase calculator 9... Coordinate converter 10... Coordinate converter 11... Power converter 12... Current transformer for current detection 13... Propulsion motor (PM)
14...Speed detector (PG)
Reference Signs List 15: Propulsion propeller 16: Power converter circuit breaker 17: AC power supply circuit breaker 18: AC power supply 19: In-ship bus system 20: Multiplier 21, 24, 25: Switch 22: Cube calculator 26: Torque reference table

The present invention relates to an electric propulsion device for an onboard system.

Figure 3 is a diagram showing the configuration of a conventional electric propulsion device control method using a vector control inverter, as shown in Non-Patent Document 1.

In FIG. 3 , reference numeral 1 denotes an electric propulsion device which is a system including components 3 to 14 described below, 2 denotes a speed setter, 3 denotes a speed controller, 4 denotes a magnetic flux command value calculator , 5 denotes a magnetization component current calculator, 6 and 7 denote current controllers, 8 denotes a phase calculator, 9 and 10 denote coordinate converters, 11 denotes a power converter, 12 denotes a current transformer, 13 denotes a propulsion motor, 14 denotes a speed detector, 15 denotes a propulsion propeller, 16 denotes a power converter circuit breaker, 17 denotes a circuit breaker for an AC power source such as a diesel generator, 18 denotes an AC power source such as a diesel generator, and 19 denotes an inboard busbar system.

The normal operation of the conventional electric propulsion device 1 shown in Figure 3 will be described.

The onboard bus system 19 is configured by connecting an AC power source 18 such as a diesel generator via a circuit breaker 17. The onboard bus system 19 is connected to the power converter 11 of the electric propulsion device 1 via a circuit breaker 16.

The power converter 11 supplies power from the onboard bus system 19 to the propulsion motor (PM) 13. The propulsion motor 13 is the power source for the propulsion propeller 15, and drives the propulsion propeller 15 with the power supplied from the power converter 11.

The speed setter 2 sets the rotational speed of the propulsion motor 13 to generate a speed target value ω ^* . The speed controller 3 amplifies the error between the speed target value ω ^* generated by the speed setter 2 and the rotational speed (actual speed ω) of the propulsion motor 13 detected by a speed detector (PG) 14, and generates a torque target value τ ^* .

Furthermore, the magnetic flux command value calculator 4 calculates a magnetic flux command value Φ2 ^* based on the actual speed ω detected by the speed detector 14, and outputs it to the magnetization component current calculator 5. The magnetization component current calculator 5 generates a magnetization component current command value Id ^* based on the magnetic flux command value Φ2 ^* from the magnetic flux command value calculator 4.

A divider 20 generates a torque component current command value Iq ^* from the above-mentioned torque target value τ ^* and magnetic flux command value Φ2 ^* .

The current transformer 12 detects the actual current of the power converter 11. The coordinate converter 9 performs coordinate conversion based on the actual current detected by the current transformer 12 and the phase θ1 determined by the phase calculator 8 based on the rotation speed (actual speed ω), and outputs a torque component current feedback Iq and a magnetization component current feedback Id. The torque component current feedback Iq is differentially amplified from the torque component current command value Iq ^* described above, and is supplied to a coordinate converter 10 for vector control via a current controller 6. The magnetization component current feedback Id is differentially amplified from the magnetization component current command value Id ^* , and is supplied to the coordinate converter 10 via a current controller 7. The coordinate converter 10 generates a power converter primary voltage reference (Vu ^* , Vv ^* , Vw ^* ) based on inputs from the current controllers 6 and 7, and operates the propulsion motor 13.

The Institute of Electrical Engineers, "Electrical Engineering Handbook", 6th edition, Vol. 21, Drive Systems, Chapter 4, Variable Speed Drives for Induction Machines, P886, Figure 43

In the conventional electric propulsion device 1 shown in FIG. 3, a torque target value is calculated by amplifying the error between the speed target value ω ^* of the speed setter 2 and the actual speed ω. However, the gain of the speed controller 2 is generally large, and even when the actual speed fluctuation is small , the torque target value τ ^* changes sharply as a result of the calculation.

In particular, in bad weather, constant load fluctuations in the electric propulsion device 1 cause fluctuations in the actual speed ω, which causes abrupt fluctuations in the torque target value τ ^* . The fluctuations in the torque target value τ ^* contribute to power fluctuations in the power converter 11 and the propulsion motor 13, but because the voltage and current of the power converter 11 are supplied from the onboard bus system 19, the result is abrupt fluctuations in the onboard bus system power 19, which has an adverse effect on the AC power source 18 such as a diesel generator that supplies power to the onboard bus system 19, and on power supply equipment.

The present invention aims to provide an electric propulsion device that can suppress power fluctuations in the ship's busbar system.

In order to achieve the above object, an electric propulsion device according to the invention as set forth in claim 1 includes a power converter connected to an inboard bus system powered by an AC power source and supplying power to a propulsion motor to which a propeller is connected to drive the propulsion motor, a speed setter for setting a target speed value for the rotational speed of the propulsion motor, a speed detector for detecting the rotational speed of the propulsion motor , a speed controller for generating a first torque command value based on a difference between the rotational speed detected by the speed detector and the rotational speed indicated by the speed target value set by the speed setter, a generation circuit for generating a second torque command value corresponding to the speed target value, which is generated by the speed controller in response to fluctuations in the rotational speed detected by the speed detector and which fluctuates less than the first torque command value, a switching circuit for exclusively switching between the first torque command value generated by the speed controller and the second torque command value generated by the generation circuit, and a magnetic flux command value calculation circuit for generating a magnetic flux command value based on the rotational speed detected by the speed detector. a current transformer that detects the current of power supplied to the propulsion motor from the power converter; a first coordinate converter that outputs a torque component current and a magnetization component current corresponding to the current detected by the current transformer; a first current controller that amplifies an error between the torque component current command value and the torque component current; a second current controller that amplifies an error between the magnetization component current command value and the magnetization component current; and a second coordinate converter that vector-controls the supply of power by the power converter based on a value of error amplified corresponding to the torque component current by the first current controller and a value of error amplified corresponding to the magnetization component current by the second current controller .

The electric propulsion device according to the invention recited in claim 2 is the electric propulsion device recited in claim 1, wherein the generation circuit comprises a cube calculator that cubes the speed target value of the rotational speed set by the speed setter, and a circuit that generates the second torque command value by calculation based on the result of the cube calculator and the rotational speed detected by the speed detector.

The electric propulsion device according to the invention recited in claim 3 is the electric propulsion device recited in claim 1, wherein the generation circuit is provided with a torque table which determines and outputs the second torque command value corresponding to the speed target value set by the speed setter, the second torque command value corresponding to each of a plurality of different rotational speed target values set by the speed setter and which fluctuates less than the first torque command value generated by the speed controller in response to fluctuations in the rotational speed detected by the speed detector.

The electric propulsion device of the present invention prevents sudden fluctuations in the torque target value, and as a result, fluctuations in the onboard bus system power can be suppressed.

1 is a block diagram showing an example of the configuration of an electric propulsion device according to a first embodiment of the present invention; FIG. 6 is a block diagram showing an example of the configuration of an electric propulsion device according to a second embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of a conventional electric propulsion device.

The following describes an embodiment of the present invention with reference to the drawings.

First Embodiment
(composition)
FIG. 1 is a diagram showing an example of the configuration of an electric propulsion device according to a first embodiment of the present invention.

In FIG. 1, reference numeral 100 denotes an electric propulsion device which is a system including components 3 to 14 and 21 to 23 described below, 2 denotes a speed setter, 3 denotes a speed controller, 4 denotes a magnetic flux command value calculator , 5 denotes a magnetization component current calculator, 6 and 7 denote current controllers, 8 denotes a phase calculator, 9 and 10 denote coordinate converters, 11 denotes a power converter, 12 denotes a current transformer, 13 denotes a propulsion motor, 14 denotes a speed detector, 15 denotes a propulsion propeller, 16 denotes a power converter circuit breaker, 17 denotes a circuit breaker for an AC power source such as a diesel generator, and 18 denotes a diesel generator. Reference numeral 19 denotes an AC power source for electric machines, etc., 19 denotes an onboard bus system, 20 denotes a divider, 21 denotes a switch for selecting the torque target value (first torque target value ) calculated by the speed controller 3, 22 denotes a cube calculator that cubes the speed setting signal from the speed setting device 2, 23 denotes a divider that calculates a torque target value (second torque target value ) from the result of the cube calculation by the cube calculator 22 and the actual speed ω, and 24 denotes a switch for selecting the torque target value (second torque target value ) calculated by the divider 24.

In FIG. 1, the same components as those in the electric propulsion device 1 shown in FIG. 3 are designated by the same reference numerals and will not be described.
(Action)
Figure 1 shows an electric propulsion device 1 having a configuration similar to that shown in Figure 3, to which a generation circuit is added that generates a torque target value τ ^* (second torque target value ) that fluctuates less than a torque target value τ ^* (first torque target value ) generated by a speed controller 3 in accordance with fluctuations in the rotational speed (actual speed ω) detected by a speed detector 14, and a switching circuit that exclusively switches between the torque target value τ ^* (first torque target value ) generated by the speed controller 3 and the torque target value τ ^* (second torque target value ) generated by the generation circuit.

In the first embodiment, a generation circuit that generates a torque target value τ ^* (second torque target value ) is composed of a cube calculator 22 that cubes the speed target value ω ^* of the rotational speed set by the speed setter 2, and a divider 23 that calculates the second torque target value based on the calculation result of the cube calculator 22 and the rotational speed (actual speed ω) detected by the speed detector 14. In addition, switches 21 and 24 are provided as a switching circuit.

In the conventional technology, the difference between the speed target value ω ^* set by the speed setter 2 and the actual speed ω set by the speed detector 14 is error-amplified by the speed controller 3 to generate the torque target value τ ^* . However, the speed controller 3 generally has a large gain, and therefore the torque target value changes sharply as a calculation result even when the actual speed fluctuation is small.

Here, it is known that the load characteristics (power-speed characteristics) of the propulsion propeller 15 are such that power is proportional to the cube of the speed, and the relationship between speed ω, torque τ, and power P is given by τ=P/ω. Therefore, by determining the torque target value τ ^* by dividing the power reference value P ^* calculated by the cube calculator 23 from the speed target value ω* of the speed setter 2 by the actual speed ω measured by the speed detector 14 using the divider ²⁴ , it is possible to generate a torque target value that does not fluctuate sharply as long as the speed target value ω ^* does not change.

When performing an operation that requires suppressing torque fluctuations , for example when the actual speed ω fluctuates due to constant load fluctuations on the electric propulsion device 1 during bad weather, the switches 21 and 24 close the switch 24 and open the switch 21. In other words, instead of the torque target value τ ^* (first torque target value ) generated by the speed controller 3, the torque target value τ ^* (second torque target value ) generated by the generation circuit (cube calculator 23, divider 23) is switched to.
(effect)
According to the first embodiment, by providing a generation circuit (cube calculator 23, divider 23) that suppresses torque fluctuations even when the actual speed ω fluctuates, and switches 21, 24 that switch from the torque target value τ ^* (first torque target value ) generated by the speed controller 3 to the torque target value τ ^* (second torque target value ) generated by the generation circuit, it is possible to control the power converter 11 using a torque target value that does not fluctuate suddenly, and as a result, it is possible to suppress power fluctuations in the power converter 11, the propulsion motor 13, and the onboard busbar system 19.
Second Embodiment
(composition)
FIG. 2 is a diagram showing an example of the configuration of an electric propulsion device according to a second embodiment of the present invention.

In FIG. 2 , reference numeral 101 denotes an electric propulsion device which is a system including components 3 to 14 and 21, 25, and 26 described below, reference numeral 2 denotes a speed setter, reference numeral 3 denotes a speed controller, reference numeral 4 denotes a magnetic flux command value calculator , reference numeral 5 denotes a magnetization component current calculator, reference numerals 6 and 7 denote current controllers, reference numeral 8 denotes a phase calculator, reference numerals 9 and 10 denote coordinate converters, reference numeral 11 denotes a power converter, reference numeral 12 denotes a current transformer, reference numeral 13 denotes a propulsion motor, reference numeral 14 denotes a speed detector, reference numeral 15 denotes a propulsion propeller, reference numeral 16 denotes a power converter circuit breaker, reference numeral 17 denotes a circuit breaker for an AC power source such as a diesel generator, reference numeral 18 denotes an AC power source such as a diesel generator, reference numeral 19 denotes an inboard bus system, reference numeral 20 denotes a divider, reference numeral 21 denotes a switch for selecting a torque target value (first torque target value ) calculated by the speed controller 3, reference numeral 25 denotes a switch for selecting a torque table 26, and reference numeral 26 denotes a torque table .

In FIG. 2, the same components as those in the electric propulsion device 1 shown in FIG. 3 are designated by the same reference numerals and will not be described.
(Action)
Figure 2 shows a configuration of the conventional electric propulsion device 1 shown in Figure 3, with the addition of a generation circuit that generates a torque target value τ ^{* (second torque target value) that fluctuates less than the torque target value τ*} ( first torque target value ) generated by the speed controller 3 in response to fluctuations in the rotational speed (actual speed ω) detected by the speed detector 14, and a switching circuit that exclusively switches between the torque target value τ ^* (first torque target value) generated by the speed controller 3 and the torque target value τ ^* (second torque target value ) generated by the generation circuit, similar to the electric propulsion device 100 in the first embodiment shown in Figure ¹ .

In the second embodiment, a generating circuit for generating the torque target value τ ^* (second torque target value ) is configured by a torque table 26. The torque table 26 is set with torque target values τ ^* (second torque target values) corresponding to each of a plurality of different rotational speed target values ω ^* set by the speed setter 2, which fluctuate less than the torque target value τ* (first torque target value ) generated by the speed controller 3 according to the speed target value ω ^* of the rotational speed set by the speed setter 2. The torque table 26 determines and outputs the torque target value τ ^* (second torque target value ) corresponding to the speed target value ^{ω *} of the rotational speed set by the speed setter 2. In addition, switches 21 and 25 are provided as a switching circuit.
In the conventional technology, the difference between the speed target value ω ^* set by the speed setter 2 and the actual speed ω set by the speed detector 14 is error-amplified by the speed controller 3 to generate the torque target value τ ^* . However, the speed controller 3 generally has a large gain, and therefore the torque target value changes sharply as a calculation result even when the actual speed fluctuation is small.

Here, by determining the torque target value τ ^* corresponding to the speed target value ω ^* of the speed setter 2 using the torque table 26, it is possible to generate a torque target value that does not change sharply as long as the speed target value ω ^* does not change.

When performing an operation that requires suppressing fluctuations in the torque target value , for example when the actual speed ω fluctuates due to constant load fluctuations in the electric propulsion device 1 during bad weather, the switches 21 and 25 close the switch 25 and open the switch 21. In other words, instead of the torque target value τ ^* (first torque target value ) generated by the speed controller 3, the torque target value τ ^* (second torque target value ) generated by the generation circuit ( torque table 26) is switched to.
(effect)
According to the second embodiment, although the power fluctuates depending on the actual speed ω, the rate of change of the actual speed ω is generally smaller than the rate of change of the output ( torque target value τ ^* (first torque target value )) of the speed controller 3. Therefore, by providing a torque table 26 that outputs a torque target value τ ^* (second torque target value ) corresponding to the speed target value ω ^* of the rotational speed set in the speed setter 2, and a switching circuit (switches 21, 25) that switches from the torque target value τ ^* (first torque target value ) generated by the speed controller 3 to the torque target value τ ^* (second torque target value ) generated by the generation circuit, the power converter 11 can be controlled by a torque target value that does not fluctuate suddenly, and as a result, power fluctuations in the power converter 11, the propulsion motor 13 and the onboard busbar system 19 can be suppressed.

The present invention is not limited to the above-described embodiments as they are, and in the implementation stage, the components can be modified and embodied without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

1, 100, 101... Electric propulsion device 2... Speed setting device 3... Speed controller 4... Magnetic flux command value calculator
Reference Signs List 5: Magnetization component current calculator 6: Current controller 7: Current controller 8: Phase calculator 9: Coordinate converter 10: Coordinate converter 11: Power converter 12: Current detection transformer 13: Propulsion motor (PM)
14...Speed detector (PG)
REFERENCE SIGNS LIST 15: Propulsion propeller 16: Power converter circuit breaker 17: AC power supply circuit breaker 18: AC power supply 19: In-ship bus system 20: Multiplier 21, 24, 25: Switch 22: Cube calculator 26: Torque table

Claims (3)

a power converter connected to an onboard bus system powered by an AC power source and configured to drive a propulsion motor to which a propeller is connected;
a speed setter for setting the rotational speed of the propulsion motor;
a speed detector for detecting a rotational speed of the propulsion motor;
a phase calculator that determines a phase based on the rotation speed detected by the speed detector;
a speed controller that generates a first torque reference based on a difference between a rotation speed detected by the speed detector and a speed reference of the rotation speed set by the speed setter;
a generating circuit for generating a second torque reference having smaller fluctuations than the first torque reference generated by the speed controller in response to fluctuations in the rotation speed detected by the speed detector;
a switching circuit that exclusively switches between a first torque reference generated by the speed controller and a second torque reference generated by the generating circuit;
a magnetic flux reference calculator and a magnetization component current calculator that generate a magnetic flux reference based on the first torque reference or the second torque reference;
a current controller that amplifies a difference between a current reference signal generated by the speed controller and the magnetization component current calculator and a detection current of a power converter;
a current transformer for detecting a current of the power converter;
and a coordinate converter for performing vector control of the power converter. The generating circuit includes:
2. The electric propulsion device according to claim 1, further comprising: a cube calculator that cubes a speed reference of the rotational speed set by the speed setter; and a circuit that calculates the second torque reference based on a result of the cube calculator and the rotational speed detected by the speed detector. The generating circuit includes:
2. The electric propulsion device according to claim 1, further comprising a torque reference table for determining the second torque reference in accordance with the rotational speed set by the speed setter, the second torque reference being associated with each of a plurality of speed references for different rotational speeds set by the speed setter, the speed reference having less fluctuation than the first torque reference generated by the speed controller in accordance with the speed reference for the rotational speed set by the speed setter.