JP2747121B2 - Variable speed drive system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

 [Object of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable speed drive system for driving a propeller of a ship by an electric motor.

[0002]

2. Description of the Related Art The configuration of a conventional marine electric propulsion system is shown in FIG. As a general system configuration, a diesel engine, a gas turbine, or a steam turbine is used as a prime mover 1 to drive a generator 2 to generate AC power. The AC power is supplied to the power converters 3L and 3R, and the controlled AC power is used as electric energy for driving the motors 4L and 4R of the propeller shafts on the port and starboard sides. That is, the power conversion device 3 and the electric motor 4 are powered by the power generated by the power plant 10 composed of the prime mover 1 and the generator 2.
Is a two-axis system that controls the speed of the propellers, adjusts the propulsion of the ship, and navigates. In general, the power converter 3 is used for driving a DC motor such as a thyristor rectifier, or for driving an AC motor such as a cycloconverter, a load commutation inverter, and a self-excited inverter.

On the other hand, the propeller characteristic of a ship has a torque-rotation speed characteristic as shown in FIG. 4 and is known as a Robinson curve. In order to perform deceleration stop and reverse acceleration from forward deceleration while the ship is traveling forward, the propeller speed is reversed. At that time, the rotation speed of the propeller (same as the rotation speed of the electric motor)
FIG. 4 shows the relationship between the torque of the propeller and the torque of the propeller. This torque-
Speed characteristics will vary with the sailing speed of the ship, for example sailing speeds faster v _a become a characteristic of a, v _b, v respectively when the _c b, characteristics indicated by a curve c. Note that v _a , v _b and v _c have a relationship of v _a > v _b > v _c . This characteristic indicates that regenerative energy is generated while the propeller speed is reduced to zero speed. That is, in the characteristic a, apparent from the range from zero speed to N ₁ speed indicates a negative torque in the forward rotation, the propeller for a ship is in progress in a direction to maintain rotation in forward rotation By receiving power. When this is viewed from the electric motor 4, a regenerative operation state, that is, a generator operation state is established, and regenerative electric power is generated. Regenerative energy (referred to as idling speed) propeller speed when the propeller shaft in a free state as shown in FIG. 5 from N ₁ occurs between the zero speed.

However, the regenerative power is supplied to the power converter 3
Power is supplied to the power plant through At this time, the generator 2 enters an operation state in which power is consumed, that is, a motor operation state, and converts electric energy into mechanical energy. As a result, the prime mover 1 and the generator 2 receive torque in the direction of acceleration. However, since a mechanical prime mover such as a diesel engine or a turbine cannot consume rotational energy, regenerated energy is converted into rotational energy of a rotary mechanical part of the prime mover 1 and the generator 2. As a result, the speed of the rotating mechanical system is increased by the absorbed energy, so that the rotating mechanical system becomes overspeed.

[0005] In order to prevent the increased speed from reaching the critical speed of the prime mover or the engine, generally, as a means for preventing this, another load on the ship is connected to the generator output to be consumed. And other methods are used.

[0006]

In the system configured as described above, the load on the ship is not fixed and when the load is not large enough to consume regenerative energy in a capacity manner. In some cases, the load cannot be handled only by the load on the ship. As a result, problems occur such as the generator output frequency fluctuating due to acceleration beyond the critical speed or fluctuation in speed.

As described above, the present invention deals with regenerative energy generated when a ship decelerates and stops while the ship is in progress, for example, by abnormally accelerating a prime mover or a generator, or by using a ship electric machine that does not cause problems such as frequency fluctuations. It is an object to provide a variable speed drive system for propulsion. [Configuration of the Invention]

[0008]

In order to achieve the above object, the present invention provides a generator driven by a prime mover and a plurality of motors each of which drives a plurality of electric motors using electric power generated by the generator as a power source. In the device for driving a propeller of a ship or the like by the plurality of electric motors, when the speeds of the plurality of electric motors are reduced and reversed,
At least one of the motors is maintained at idle speed or higher so as to absorb regenerative electric power generated at the time of deceleration of another motor, and after the other motor shifts from deceleration to reverse rotation and enters a power running state, the remaining motors This is a variable speed drive system provided with a means for decelerating and reversing the speed of the generator, and configured to always control the load of the generator to a positive state.

[0009]

FIG. 1 shows the configuration of an embodiment of the present invention. The configurations of the power plant section and the propulsion plant sections on the starboard and port sides are the same as those in the prior art, and are denoted by the same reference numerals.

In this embodiment, the power converters 3L and 3R are used to always ensure power consumption in the power running state for the generator 2.
The power detectors 13L and 13R are provided on the input side of. Also, determiners 14L and 14R for determining power running, regeneration and the magnitude thereof from the detected power are provided, and transmit the information to the power converters (3L and 3R). FIG. 2 shows an operation pattern according to this embodiment.

In FIG. 2, the propeller speed (motor speed) n _{R of} the starboard shaft is shown as n _L , and the propeller speed of the port shaft is shown as n _L. Also, starboard shaft motor output P _R, also a port axis motor output indicated by P _L. When a deceleration / reverse command is received at time t ₀ during navigation at the propeller speed N ₀ , one of the two axes is maintained at the idle speed or higher. Figure 2 shows the port axis as N
_In this example, the other starboard axle is confirmed to be in the power running state by the signal from the determiner 14L in accordance with the command, and then the deceleration is started and the idle speed N ₁ From the time t to zero speed (time t ₁ ), negative power, that is, regenerative operation is performed. Meanwhile, the port axis generates positive power, so the total is positive power. Next, starboard entering in the reverse direction to accelerate held in the reverse speed N ₂ which can ensure accelerated positive power between t ₁ ~t _2. Starboard side confirms that secured the positive power at time t ₂ the signal decision unit 14R, one port side is led to the speed of the opposite shaft side at time t ₂ starts to decelerate, reverse speed N in both axes both
It becomes ₂ .

By performing the above-described operation, the total electric power can always be set to a positive value, and regenerative electric power is not supplied to the generator. Can be prevented.

In this embodiment, an example of detecting the state of power running and regeneration is shown. However, it is necessary to detect the electric power of the generator 2 and sequentially operate each axis so as to always maintain the power generation state. It is the gist of the invention.

[0014]

According to the present invention, the regenerative energy generated when the direction of rotation of the propeller is changed when the ship is decelerated, stopped, or moved backward (forward) is utilized by utilizing the multi-axis propulsion system. The generator can always be in a power generation state by sequentially decelerating the shaft without decelerating all at once. As a result, it is possible to provide a variable speed drive system for electric propulsion of a ship that can operate the ship without having to coordinate with other loads on the ship and without abnormally accelerating the prime mover and the generator.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment according to the present invention;

FIG. 2 is a diagram illustrating the operation of the embodiment.

FIG. 3 is a configuration diagram of a conventional electric propulsion system.

FIG. 4 is a diagram showing propeller characteristics.

FIG. 5 is an explanatory diagram of generation of regenerative energy.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Prime motor 2 ... Generator 3L, 3R ... Power converter 4L, 4R ... Electric motor 5L, 5R ... Propeller 10 ... Power plant 11 ... Port propulsion plant 12 ... Starboard propulsion plant 13L, 13R ... Power detector 14L, 14R ... Judgment vessel

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02P 7/67 H02P 7/74

Claims (1)

(57) [Claims] 1. A generator driven by a prime mover, and a plurality of power converters each of which drives a plurality of motors using electric power generated by the generator as a power source. In the driving device,
When the speeds of the plurality of motors are reduced and reversed, at least one of the motors is maintained at idle speed or higher so as to be able to absorb regenerative power generated when the other motors are decelerated, and the other motors are rotated from the deceleration to the reverse. A variable speed drive system comprising: means for decelerating and reversing the remaining electric motor after a transition to the power running state, and controlling the load of the generator to be always in a positive state.