Electric propulsion system for ship

Abstract

To control a propulsion electric motor optimally with a small number of persons by suppressing power-supply power fluctuation by automatically switching a rate control and a torque control even when a load change of the propulsion electric motor occurs in a sea area and a stormy weather.SOLUTION: In an electric propulsion system having a motor 1 for propulsion to which power is supplied from a bus bar 3 in a vessel through an inverter 4, a propeller 2 driven by the motor, a torque detector 9 provided near the motor, a rate detector 10, a current detector 11, and a control device 5 to which a signal from each detector is inputted and from which a control signal is outputted to the inverter, the control device has a detection unit 6 to which the signal from each detector is inputted, a switchover control unit 7 outputting a switchover control signal to the inverter, and a setting unit 8 outputting various setting values to the switchover control unit, and the switchover control unit outputs to the inverter the switchover control signal switching from a rate control to a torque control when a torque change rate of a torque detected by the torque detector exceeds a predetermined setting value while the motor is in a state of the rate control.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an electric propulsion system that optimally controls a propulsion electric motor used in, for example, a ship in response to load changes. [Background technology]

[0002] Propulsion motors used on ships and other vessels are generally controlled and adjusted by inverters to reach a target speed and maintain that speed. However, when there are waves due to factors such as ocean conditions or rough weather, the load on the rotating machine changes in addition to the propulsion force. The inverter responds to these changes by increasing or decreasing the power supply, but depending on the amount of power required, this can lead to problems such as the need to increase the number of generators in operation, or increased fuel consumption due to the generator load ratio. Furthermore, repeated governor operation increases the burden on the equipment, shortening its lifespan.

[0003] To address this problem, motor control is switched from speed control to torque control or to constant power supply control by human operation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5561468 Summary of the Invention [Problem to be solved by the invention]

[0005] The conventional electric propulsion systems described above required manual monitoring of the electric motor and switching between speed control and torque control, but this required a large number of personnel for monitoring and operation, and also posed a significant workload.

[0006] An embodiment of the present invention has been made to solve the above-mentioned problems, and aims to provide an electric propulsion system that can optimally control the propulsion motor with a small number of personnel, even when changes in the load on the motor occur in sea areas or during rough weather. [Means for solving the problem]

[0007] In order to solve the above problems, the electric propulsion system of this embodiment has a propulsion motor supplied with power from an inboard bus via an inverter, a propeller driven by the electric motor, a torque detector, a speed detector, and a current detector arranged near the electric motor, and a control device that receives signals from the detectors and outputs a control signal to the inverter, wherein the control device comprises a detection unit that receives signals from the detectors, a switching control unit that outputs a switching control signal to the inverter, and a setting unit that outputs various setting values ​​to the switching control unit, and is characterized in that when the torque change rate of the torque detected by the torque detector exceeds a predetermined setting value while the electric motor is in a speed control state, the switching control unit outputs a switching control signal to the inverter to switch from speed control to torque control.

[0008] Furthermore, the electric propulsion system according to this embodiment comprises a propulsion motor supplied with power from an inboard bus via an inverter, a propeller driven by the motor, a torque detector, a speed detector, and a current detector arranged in the vicinity of the motor, and a control device that receives signals from the detectors and outputs a control signal to the inverter, wherein the control device comprises a detection unit that receives signals from the detectors, a switching control unit that outputs a switching control signal to the inverter, and a setting unit that outputs various setting values ​​to the switching control unit, and is characterized in that when the rate of change of the speed detected by the speed detector while the motor is in a torque control state becomes equal to or less than a predetermined setting value, the switching control unit outputs a switching control signal to the inverter to switch from torque control to speed control. [Effects of the Invention]

[0009] According to this embodiment, even when the load on the motor changes due to sea conditions or rough weather, the propulsion motor can be optimally controlled with a small number of personnel. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing the overall configuration of an electric propulsion system according to the present invention; [Figure 2] 5A and 5B are diagrams showing examples of behavior of the torque change rate and switching timing. [Figure 3] 10A and 10B are diagrams showing examples of the behavior of the speed change rate and switching timing. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric propulsion system according to the present invention will now be described with reference to the drawings.

[0012] [Overall configuration] As shown in Figure 1, the electric propulsion system according to this embodiment is composed of a propulsion propeller 2 driven by an electric motor 1 installed, for example, on a ship, an inboard bus 3 that supplies power to the electric motor 1 and onboard loads, a control device 5 that controls the electric motor 1, and a torque detector 9, a speed detector 10, and a current detector 11 arranged near the electric motor 1.

[0013] The control device 5 is composed of a detection unit 6 to which signals from each detector are input, a switching control unit 7 that outputs switching signals for torque control / current control, etc. to the inverter 4, and a setting unit 8 that sets thresholds, etc. to be output to the switching control unit 7.

[0014] 1 shows an example in which the torque detector 9 and current detector 11 are provided near the electric motor 1, but the inverter 4 may have the torque detection function and current detection function. Furthermore, the speed detector 10 is also provided near the electric motor 1, but the speed of the electric motor 1 may be estimated and calculated by monitoring the voltage, etc., within the inverter 4. This makes it possible to reduce the number of detectors and prevent malfunctions, simplifying the device configuration and improving reliability.

[0015] [First embodiment] The electric propulsion system according to the first embodiment of the present invention, while in a speed control state, monitors the torque change rate of the torque detected by the torque detector 9 to detect a change in the load on the electric motor 1, and performs control to switch from speed control A to torque control B when the torque change rate exceeds a predetermined set value a.

[0016] Figure 2 is a diagram illustrating the behavior of the torque change rate and the timing for switching from speed control A to torque control B. This is an example of control that switches from speed control A to torque control B when the torque change rate (dT / dt) exceeds a set value a.

[0017] Although the control example shown in FIG. 2 shows an example of switching based on the rate of change of torque, the rate of change of motor output, inverter input power, or inverter output power that changes in conjunction with torque may also be used.

[0018] Furthermore, the control to be switched to is not limited to torque control, but may be motor output control, inverter input power control, or inverter output power control.

[0019] (Variation 1) In this first modification, if the torque change rate of the torque detected by the torque detector 9 exceeds a predetermined set value during the speed control state, the switching control unit 7 outputs a switching control signal to the inverter 4 to switch the speed control gain. Furthermore, the value of the speed control gain to be switched may be changed appropriately depending on the magnitude of the torque change rate.

[0020] (Variation 2) In this second variant, if the torque change rate of the torque detected by the torque detector 9 exceeds a predetermined set value during speed control, the switching control unit 7 outputs a switching control signal to the inverter 4 to enable the torque limiting function. Furthermore, the torque limit function sets a torque limit value, but the magnitude of this torque limit value may be changed as appropriate.

[0021] (Variation 3) In this third modification, when the speed change rate of the speed detected by the speed detector 10 exceeds a predetermined set value during the speed control state, the switching control unit 7 outputs a switching control signal to the inverter 4 to switch the speed control gain. Furthermore, the value of the speed control gain to be switched may be changed appropriately depending on the magnitude of the speed change rate.

[0022] (Variation 4) In this third modification, if the speed change rate of the speed detected by the speed detector 10 exceeds a predetermined set value during the speed control state, the switching control unit 7 outputs a switching control signal to the inverter 4 to disable the torque limiting function. Furthermore, the torque limit function sets a torque limit value, but the magnitude of this torque limit value may be changed as appropriate.

[0023] (effect) According to the first embodiment, even if a load change occurs on the propulsion motor in the speed control state when the vessel is in seawater or in rough weather, power supply fluctuations can be suppressed by automatically switching from speed control to torque control, and the propulsion motor can be optimally controlled with a small number of personnel.

[0024] [Second embodiment] The electric propulsion system according to the second embodiment monitors the rate of change of the speed signal detected by the speed detector 10 during the torque control state, and switches from torque control B to speed control A when the rate of change of the speed becomes equal to or less than a predetermined set value b.

[0025] Figure 3 is a diagram illustrating the behavior of the speed change rate and the timing for switching from torque control B to speed control A. This is an example of control that switches from torque control B to speed control A when the speed change rate (dN / dt) falls below a set value b.

[0026] (Variation 5) In this fifth modification, when the rate of change of the speed detected by the speed detector 10 exceeds a predetermined set value during the torque control state, the switching control unit 7 outputs a switching control signal to the inverter 4 to switch the torque control gain. Furthermore, the value of the torque control gain to be switched may be changed appropriately depending on the magnitude of the speed change rate.

[0027] (Variation 6) In this variant 6, if the speed change rate of the speed detected by the speed detector 10 exceeds a predetermined set value during the torque control state, the switching control unit 7 outputs a switching control signal to the inverter 4 to enable the speed limiting function. Furthermore, the speed limit function sets a speed limit value, but the magnitude of this speed limit value may be changed as appropriate.

[0028] (Variation 7) In this seventh modification, when the torque change rate of the torque detected by the torque detector 9 exceeds a predetermined set value during the torque control state, the switching control unit 7 outputs a switching control signal to the inverter 4 to switch the torque control gain. Furthermore, the value of the torque control gain to be switched may be changed appropriately depending on the magnitude of the torque change rate.

[0029] (Variation 8) In this variant example 8, if the torque change rate of the torque detected by the torque detector 9 exceeds a predetermined set value during the torque limiting state, the switching control unit 7 outputs a switching control signal to the inverter 4 to disable the speed limiting function. Furthermore, the speed limit function sets a speed limit value, but the magnitude of this speed limit value may be changed as appropriate.

[0030] (effect) According to the second embodiment, even if a load change occurs on the electric motor during torque control, the electric motor can be made to follow the speed by automatically switching from torque control to speed control, thereby enabling optimal control of the propulsion motor with a small number of personnel.

[0031] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be combined or implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0032] 1...electric motor, 2...propeller, 3...inboard busbar, 4...inverter, 5...control device, 6...detection unit, 7...switching control unit, 8...setting unit, 9...torque detector, 10...speed detector, 11...current detector, A...speed control, B...torque control

Claims

1. An electric propulsion system having a propulsion motor supplied with power from an inboard bus via an inverter, a propeller driven by the motor, a torque detector, a speed detector, and a current detector arranged near the motor, and a control device that receives signals from the detectors and outputs control signals to the inverter, the control device includes a detection unit to which signals from the detectors are input, a switching control unit that outputs a switching control signal to the inverter, and a setting unit that outputs various setting values ​​to the switching control unit; an inverter for controlling the torque detector to detect a torque change rate exceeding a predetermined set value while the electric motor is in a speed control state; and an inverter for controlling the torque detector to detect a torque change rate exceeding a predetermined set value while the electric motor is in a speed control state.

2. 2. The electric propulsion system according to claim 1, wherein, when a torque change rate of the torque detected by the torque detector exceeds a predetermined set value, the switching control unit outputs a switching control signal to the inverter to switch the speed control gain.

3. 2. The electric propulsion system according to claim 1, wherein, when a torque change rate of the torque detected by the torque detector exceeds a predetermined set value, the switching control unit outputs a switching control signal to the inverter to enable a torque limiting function.

4. 2. The electric propulsion system according to claim 1, wherein, when a rate of change of the speed detected by the speed detector exceeds a predetermined set value, the switching control unit outputs a switching control signal to the inverter to switch the speed control gain.

5. 2. The electric propulsion system according to claim 1, wherein, when a rate of change of the speed detected by the speed detector exceeds a predetermined set value, the switching control unit outputs a switching control signal to the inverter to disable a torque limiting function.

6. An electric propulsion system having a propulsion motor supplied with power from an inboard bus via an inverter, a propeller driven by the motor, a torque detector, a speed detector, and a current detector arranged near the motor, and a control device that receives signals from the detectors and outputs control signals to the inverter, the control device includes a detection unit to which signals from the detectors are input, a switching control unit that outputs a switching control signal to the inverter, and a setting unit that outputs various setting values ​​to the switching control unit; an inverter for controlling the speed of the electric motor when the speed change rate of the speed detected by the speed detector is equal to or less than a predetermined set value; and an inverter for controlling the speed change rate of the electric motor when the speed change rate of the speed detected by the speed detector is equal to or less than a predetermined set value.

7. 7. The electric propulsion system according to claim 6, wherein, when a rate of change of the speed detected by the speed detector exceeds a predetermined set value, the switching control unit outputs a switching control signal to the inverter to switch the torque control gain.

8. 7. The electric propulsion system according to claim 6, wherein, when a speed change rate of the speed detected by the speed detector exceeds a predetermined set value, the switching control unit outputs a switching control signal to the inverter to enable a speed limiting function.

9. 7. The electric propulsion system according to claim 6, wherein, when a torque change rate of the torque detected by the torque detector exceeds a predetermined set value, the switching control unit outputs a switching control signal to the inverter to switch the torque control gain.

10. 7. The electric propulsion system according to claim 6, wherein, when a torque change rate of the torque detected by the torque detector exceeds a predetermined set value, the switching control unit outputs a switching control signal to the inverter to disable a speed limiting function.

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