JP2610585B2 - Frequency control device for main shaft drive generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main shaft drive power generator for a marine vessel. In the case where the output frequency is controlled by a digital controller, the frequency control of the main shaft drive power generator can be performed with high speed and high accuracy. Related to the device.

[0002]

2. Description of the Related Art A main shaft drive generator is a system for generating power by driving a generator by a main engine of a ship, and has a great effect on energy saving and maintenance, and is used in many ships.

FIG. 4 shows an example of a configuration diagram of a conventional main shaft drive generator. In the figure, 1 is a shaft generator, 2 is a converter, 3 is an inverter, 4 is a synchronous phase adjuster, 5 is a main engine, 6 is a propeller, 7 is a load, 8 is a circuit breaker, 9 is a bus, 10 is a gear, 11 is a pulse sensor, 12 is F / V
A converter, 13 is a counter, 14 is a frequency indicator, 15 is a digital controller, 16 is a first voltage regulator for controlling the terminal voltage of the synchronous phase shifter 4, and 17 is a terminal voltage of the shaft generator 1. A second voltage regulator, 18 is a current detector, 1
51 is a first A / D converter, 152 is an output frequency command setter, 153 is a frequency controller, 154 is a second A / D converter, and 155 is a dot angle command value of the inverter 3 and the converter 2. A current controller for calculation, 156 is a phase controller of the converter 2, and 157 is a phase controller of the inverter 3.
In the digital controller 15, 151 to 157 shown in FIG.
Are processed in time series by software, but for simplicity of description, each element is shown as being present independently in the figure.

Next, the operation of the conventional main shaft drive generator will be described with reference to FIG.

[0005] The main engine 5 drives a propeller 6,
At the same time, the shaft generator 1 is driven. The rotation speed of the main engine 5 changes depending on the traveling state. The magnitude of the terminal voltage of the shaft generator can be controlled to a desired value by the second voltage regulator 17, but the frequency varies depending on the engine speed. Therefore, the AC is once converted into DC by the converter 2 and is again converted into AC power by the inverter 3.

The synchronous phase adjuster 4 supplies reactive power to the inverter and the load to keep the voltage of the bus 9 constant. In order to keep the output frequency of the inverter 3, that is, the frequency of the bus, constant, it is sufficient to supply electric power according to the load. The power supplied from the shaft generator to the load is proportional to the output current of the shaft generator.

The pulse sensor 11 generates a pulse according to the rotation of the gear 10 and is converted by an F / V converter 12 into a voltage signal proportional to the frequency. This signal is taken into the digital controller 15 by the A / D converter 151.
The signal of the pulse sensor 11 is converted into a digital frequency value by the counter 13 and displayed on the frequency display 14.

In the digital controller 15, a command value of a current flowing through the frequency controller 153 is determined so that the detected output frequency matches the set value of the output frequency command setter 152. The current controller 155 reads the signal of the current detector 18 by the A / D converter 154, and determines a turning angle of the converter / inverter such that the signal becomes a current command value. Each of the phase controllers 156 and 157 fires the thyristor of each of the converters 2 and 3 at a predetermined ignition angle. The obtained power of the constant frequency and constant voltage is supplied to the load 7 through the bus 9 through the circuit breaker 8. F / V converter 12 and A / D converter 1
Reference numeral 51 denotes a high speed, and the frequency is detected at a high speed. Therefore, the output frequency can be controlled at a high speed.

[0009]

According to the main-shaft driving power generator operated as described above, a power source having a constant frequency and a constant voltage can be obtained by the power of the main engine, which is effective for energy saving and maintenance. . However, the conventional system has a problem in the control accuracy of the output frequency. Hereinafter, the details will be described.

In the main shaft drive generator shown in FIG. 4, an analog value is used for detecting the output frequency. Analog frequency detection has the merit that high-speed detection is possible, but high-precision detection is not possible due to temperature drift of the detection signal. The A / D converter also has a temperature drift. The error of the detection signal has a small effect on the transient characteristics, but has a large effect on the steady control accuracy. There is a problem in that control accuracy in a steady state cannot be obtained by detection via an analog signal.

If the output frequency detection is digitized using the signal from the counter 13, the detection accuracy can be obtained. However, in order to obtain a high-speed and high-resolution signal comparable to analog detection, the number of teeth of the gear must be tens. It had to be doubled, which was not realistic.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to enable high-speed, high-precision frequency detection.
It is another object of the present invention to provide a control device for a main shaft drive power generation device capable of high-speed response and high-accuracy output frequency control.

[0013]

In order to achieve the above object, a first aspect of the present invention is a shaft generator driven by a main engine of a ship, and a converter for converting an output of the shaft generator into a direct current. An inverter that converts a DC output of the converter into an AC, a synchronous phase adjuster that supplies reactive power to the inverter and the load, and an output of the shaft generator such that a frequency of the synchronous phase adjuster becomes a predetermined value. In a main shaft drive generator including a frequency controller for calculating a current command value and a current controller for controlling a turning angle of the converter and the inverter so that an output current matches the output current command value, the frequency is represented by a digital value. And a second frequency detecting means for detecting a frequency based on an analog value. A signal from the first frequency detecting means is provided with a low-pass filter. Through filter, signals from the second frequency detecting means through a high pass filter, the frequency detection signal by adding both, characterized in providing the frequency detection signal to the frequency controller

[0014]

According to the present invention, the output frequency of the shaft generator can be detected at high speed and with high accuracy, and high-speed response and high-accuracy output frequency control can be realized.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. The present embodiment differs from the frequency control device of the main shaft drive power generator of the conventional example of FIG. 4 already described in that a signal synthesizer 158 is provided, and the other configurations are the same. The same reference numerals are given to the portions, and the description thereof will be omitted.

Therefore, the signal synthesizer 158 will be described first with reference to the block diagram of FIG.

As shown in FIG. 2, the signal synthesizer 158 includes a low-pass filter 200, a high-pass filter 201, and an adder 202. In the figure, Tc represents a filter time constant, and S represents a differential operator. Although shown as independent elements for simplicity of illustration, the signal synthesizer 158 is also processed by software like the other elements in the digital controller 15.

Next, the operation of this embodiment will be described with reference to FIGS. 1 and 2, and FIG. 3 showing a frequency-gain characteristic diagram of each signal / element in the signal combiner 158.

The frequency detection signal based on the digital value from the counter is a signal having a high detection accuracy as shown in FIG. 3A but having only a low-frequency characteristic. Also F / V
The frequency detection signal obtained by converting the analog value into a digital value from the converter is a signal having a good high-frequency characteristic as shown in FIG. 3B, but having a large error in the low frequency as described above. On the other hand, the signal of FIG.
3 (B) is applied to the signal of FIG. 3 (D), and then combined by an adder 202 to obtain the signal of FIG. 3 (E). The final speed detection signal shown is obtained.

As shown in FIG. 1, frequency control is performed by this signal (E). Since the signal (E) has a small error in a low frequency range, no steady-state error in frequency control occurs. Since there is also a sufficient high-frequency gain, high-speed response control can be performed by increasing the control gain. There is some error in the high frequency range, but there is no problem since the control gain changes only transiently by the error. Therefore, high-speed response and high-accuracy frequency control can be realized.

In the above-mentioned embodiment, the method of directly taking in the digital frequency signal from the counter has been described. However, a method of taking in by means such as serial data transmission may be used. Also, the counter has been described as an example of the digital value frequency detecting means. However, the present invention is not limited to this, and the same effect as in the above embodiment can also be obtained by measuring the pulse period and calculating the reciprocal thereof to determine the frequency. Having. In that case, there is a method in which the reciprocal operation is performed in a digital controller instead of the detector. The pulse proportional to the frequency may be generated not by a combination of a gear and a pulse sensor but by a pulse signal generated by applying an output voltage to a PLL. The analog frequency detector is not limited to the configuration of the pulse sensor and the F / V converter, but may be a tach generator.

In the above description, each element in the digital controller has been described as a system using software. However, it is needless to say that the digital controller can be realized by a system using independent digital hardware.

[0024]

As described above, according to the present invention,
This has the effect that high-speed and high-accuracy frequency detection is possible, and high-speed response and high-accuracy output frequency control can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a detailed block diagram of the signal combiner of FIG. 1;

FIG. 3 is a frequency-gain characteristic diagram of each signal in FIG. 1;

FIG. 4 is a block diagram showing an example of a conventional frequency control device of a main shaft drive power generator.

[Explanation of symbols]

1 ... shaft generator, 2 ... converter, 3 ... inverter, 4 ...
Synchronous phase adjuster, 5: main engine, 6: propeller, 7: load, 8: breaker, 9: bus, 10: gear, 11: pulse sensor, 12: F / V converter, 13: counter, 15
... Digital control device, 18 ... Current detector, 151 ... First A / D converter, 152 ... Output frequency command setting device, 1
53: frequency controller, 154: second A / D converter, 1
55: a current controller for calculating the arc angle command value of the inverter 3 / converter 2; 156: a phase controller of the converter 2; 157: a phase controller of the inverter 3; 158: a signal synthesizer; 200: a low-pass filter; ... high-pass filter, 202 ... adder.

Claims (1)

(57) [Claims] 1. A shaft generator driven by a main engine of a ship, a converter for converting the output of the shaft generator to DC, an inverter for converting the DC output of the converter to AC, and an inverter and a load. A synchronous phase shifter that supplies reactive power, a frequency controller that calculates an output current command value of the shaft generator so that the frequency of the synchronous phase shifter becomes a predetermined value, and an output current that is equal to the output current command value. In the main shaft drive power generating device comprising a current controller for controlling the ignition angle of the converter and the inverter so as to match,
First frequency detecting means for detecting a frequency by a digital value, and second frequency detecting means for detecting a frequency by an analog value; a signal from the first frequency detecting means passes through a low-pass filter; A signal from the second frequency detecting means is passed through a wide-pass filter, the two are added to form a frequency detection signal, and the frequency detection signal is provided to the frequency controller. apparatus.