JPH0140287Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention is a constant frequency power supply device for a fishing boat, in particular, the output of an alternator driven by an engine is rectified into a DC voltage, and the rectified DC voltage is set in advance by a series diode type inverter. In a power supply device for a fishing boat that converts the voltage into a three-phase alternating current voltage with a frequency and supplies it to load equipment, a compensation circuit is fixed on the output side of the inverter to always maintain the output side power factor below a predetermined power factor. This invention relates to a constant frequency power supply device for a fishing boat, which is designed to stabilize the supply voltage by connecting the power source to a constant frequency. Generally, in the case of a fishing boat, for example, when going out to fish, it is necessary to arrive at the fishing ground quickly, so the engine is rotated at a high speed to increase the sailing speed. However, when approaching fishing grounds or returning to port, the vessel should reduce its sailing speed. in this way,
The sailing speed of fishing boats needs to be increased or decreased depending on the situation. Therefore, the rotational speed of the engine that drives the fishing boat can also be changed in accordance with the desired sailing speed. In addition, fishing boats have refrigerators,
Equipment such as winches and pumps are mounted, and power equipment for driving these equipment, that is, a generator driven by the engine is installed. An induction motor is often used as a drive source for the refrigerator, winch, pump, etc., and an alternating current generator is generally used as the generator. As mentioned above, when the rotational speed of the engine is changed in accordance with the cruising speed of the fishing boat, the output frequency of the alternator driven by the engine changes, so the rotational speed of the induction motor changes. Therefore, stable operation of the refrigerator and other equipment is not desired. Therefore, various constant frequency power supply devices have been considered that maintain the output frequency of the alternator constant even if the engine speed changes. The constant frequency power supply device uses a series diode type inverter that rectifies the AC output of the AC generator into DC and converts the rectified DC voltage into a three-phase AC voltage having a predetermined frequency. Compared to other types of power supplies, constant frequency power supplies can be used under heavy inductive loads, and their large commutation capacity makes them suitable for overcurrent loads, so they are popular on fishing boats and other vessels that use many induction motors. used in However, the constant frequency power supply device using the series diode type inverter described above also has the following drawbacks. That is, the drawback is that, as is generally known, the voltage waveform of the output of the inverter changes depending on the power factor of the load. Therefore, if the power factor of the load differs, even if the average value of the output voltage of the inverter is the same, the effective value will be different.
As mentioned above, in cases such as fishing boats, there are various types of loads, so the power factor of the loads varies greatly.
If the effective value of the output voltage of the inverter becomes smaller due to a change in the power factor of the load,
The motor etc. will be unable to generate sufficient torque, and in severe cases, the motor may burn out. Therefore, in order to solve the above-mentioned drawbacks, measures have been considered to control the input voltage of the inverter so that the output voltage (effective value) of the inverter becomes constant. The input voltage of the inverter must be controlled by detecting the voltage as an effective value. Further, a delay occurs in the control, making it unstable, and especially when the load is an induction motor, the power factor of the load changes variously, and if the load factor is light, the hunting phenomenon is likely to occur, which is undesirable. Furthermore, if there is an unbalance in the load between the phases and the voltage of each phase is unbalanced, there is a problem that cannot be solved by controlling the inverter input voltage as described above. The purpose of the present invention is to solve the above-mentioned drawbacks and problems by rectifying the alternating current output of an alternator driven by an engine and converting it into direct current voltage. By connecting a compensation circuit to the output side of a series diode-type inverter that converts the voltage into a three-phase AC voltage with a specified frequency to a compensation circuit that always maintains the output side power factor below a specified value, the power factor of the load can be reduced. It is an object of the present invention to provide a constant frequency power supply device for a fishing boat that can stabilize the supply voltage even when the load between the phases changes or when the load between each phase is in an unbalanced state. This will be explained below with reference to the drawings. Fig. 1 is an electrical system diagram of an embodiment of a fishing boat using the constant frequency power supply device for fishing boats of the present invention, Fig. 2 is a block diagram for explaining an embodiment of the invention, and Fig. 3 is a diagram of an embodiment of the fishing boat of the present invention. 1 shows a circuit diagram of an embodiment of a test device for testing the effect on an unbalanced load when using a test device. 1 and 2, reference numeral 1 in the drawings indicates a main engine, 2 an auxiliary engine, 3 to 5 an alternating current generator, and 6 a constant frequency device. Further, since the constant frequency device 6 is well-known, only the main part thereof, that is, the thyristor 601 is shown in FIG.
A rectifier consisting of 607 to 606, thyristors 607 to 612, and diodes 613 to 6
18, capacitors 619 to 624, reactors 625 and 626, feedback diode group 627
The inverter is shown in a simplified manner, and the control circuit section is omitted. 7
8 and 9 are switching switches 10, 11, 11-1 to 11-5, 12-.
1, 12-2, 13-1 to 13-10 and 14-1 to 14-6 are no-use breakers, 15 is a limiter, 16 and 17 are Scott transformers, 18-1 to 18-7 are motors, 19 and 20 are ammeters, 21 and 22 are voltmeters, and 23 is a frequency meter. As mentioned at the beginning of this specification, the constant frequency device 6
It is known that the output voltage waveform of the series diode type inverter (shown in FIG. 2) changes depending on the power factor of the load. As shown in FIG. 1, a fishing boat has many motors 18.
-1 to 18-7 are installed. Therefore,
Since the motors 18-1 to 18-7 operate differently, the power factor of the load changes and the voltage waveform of the output of the constant frequency device 6 changes. In order to stabilize the voltage waveform, in the present invention, as shown in FIGS. 1 and 2, a compensation circuit 7 is connected to the output side of the constant frequency device 6, so that the load is always Efforts are made to satisfy the condition shown in equation (1). That is, L/R>1/6f...(1) However, in equation (1), L is the inductance of the load impedance, R is the resistance, and is the output frequency of the constant frequency device 6. Also, if the power factor of the load is cosφ, φ=tan ^-1 ωL/R...(2) However, in equation (2), ωL is the inductive reactance, and from equation (1), ωL/R >ω/6=2π/6=π/3 ...(3) Furthermore, from equations (2) and (3), φ>46° ...(4) Therefore, the power factor of the load cosφ is From equation (4), cosφ<0.7, that is, so that the power factor of the load is always 0.7 or less,
The above-mentioned repair circuit 7 may be selected. The compensation circuit 7
In selecting the power factor of the reactor, the power factor of the reactor can be set to about 0.05, and the loss is almost negligible, so it is desirable that the compensation circuit 7 be constructed of a reactor. Furthermore, the present invention in which the compensation circuit 7 is connected to the output side of the constant frequency device 6 can also prevent the occurrence of unbalanced voltage between phases due to the aforementioned unbalanced load. That is, the test results using the test equipment shown in Figure 3 are shown in Table (1), and it is clear that the present invention is effective in preventing voltage imbalance caused by unbalanced loads. be. Note that numerals 6 and 7 in FIG. 3 correspond to FIGS. 1 and 2, 24 is a three-pole switch, 25-1
25-3 to 25-3 are voltmeters, 26-1 to 26-
3 represents the load. In addition, the above-mentioned repair circuit 7
is selected to have a capacity of 3KVA and a power factor cosφ of 0.05.

[Table] As explained above, according to the present invention, the AC output of the AC generator driven by the engine is rectified and converted into DC voltage, and the converted DC voltage is converted to a predetermined frequency. By connecting a compensation circuit to the output side of a series diode-type inverter that converts the power factor into a three-phase AC voltage, the power factor of the output side is always kept below a predetermined value. Therefore, it is possible to provide a constant frequency power supply device for a fishing boat that can stabilize the supply voltage even when the load is unbalanced. The breaker 13-1 shown in FIG. 1 is configured to be automatically turned on and off by detecting voltage fluctuations caused by unbalance or flicker of the inverter output voltage using an electromagnetic switch or the like. This can be done at will.

[Brief explanation of the drawing]

Fig. 1 is an electrical system diagram of an embodiment of a fishing boat using the constant frequency power supply device for fishing boats of the present invention, Fig. 2 is a block diagram for explaining an embodiment of the invention, and Fig. 3 is a diagram of an embodiment of the fishing boat of the present invention. 1 shows a circuit diagram of an embodiment of a test device for testing the effect on an unbalanced load when using the following. In the diagram, 1 is the main engine, 4 is the alternator, and 6 is the main engine.
7 represents a constant frequency device, and 7 represents a compensation circuit.

Claims (1)

[Scope of utility model registration request] an engine, an alternator driven by the engine, a rectifier for rectifying the output of the alternator, and a DC voltage rectified by the rectifier into a three-phase AC voltage having a predetermined frequency. A power supply device for a fishing boat, which is equipped with a serial diode-type inverter for conversion, and has a load circuit including at least a refrigeration drive motor and a winch drive motor connected to the output side of the inverter so as to be turned on and off. Compensation that has a predetermined capacity on the three-phase output side of the inverter and maintains the power factor on the output side of the inverter below the predetermined power factor when the load circuit is under any load from heavy load to light load. A constant frequency power supply device for a fishing boat, characterized in that a circuit is connected in a fixed manner.