JPH079100U - Synchronous voltage detection circuit for marine shaft power generation system - Google Patents

Abstract

(57) [Abstract] (Modified) [Purpose] To provide a synchronous voltage detection circuit for a ship shaft power generation system that can detect a ripple voltage value of the detected voltage value without increasing even when the frequency or phase changes. . [Structure] In the synchronous voltage detection circuits 1 and 2 of a ship shaft power generation system that keeps the three-phase main circuit voltage of a converter or an inverter stable, instrument transformers 6 and 7 for detecting the three-phase main circuit voltage, and Rectifier for three-phase full-wave rectification of secondary output and A / D for analog / digital conversion of its output
The converter 34, a phase-locked loop circuit that detects the voltage phase of the secondary output of the instrument transformer, and a decoding circuit 37 that generates a timing pulse signal from a specific value of the counter output of the circuit, The voltage of the circuit can be stably converted into a digital amount even if the frequency and phase change without increasing the time constant of the smoothing circuit.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a marine shaft power generation system, and more particularly to a synchronous voltage detection circuit for a marine shaft power generation system.

[0002]

[Prior art]

 FIG. 4 shows a configuration of a conventional shaft power generation system for a ship in a single line connection diagram. In the figure, 12 is a power converter, 21 is a propulsion motor for a ship, 22 is a shaft generator, 23 is a propeller for propulsion, 24 is a synchronous phase modulator, 25 is a main circuit breaker, and 26 is a power bus of the ship. In addition, the power conversion device 12 includes voltage detection open circuits 1 and 2, phase-locked loop circuits (hereinafter referred to as PLL circuits) 3 and 4, a power conversion control circuit 5, an instrument transformer (PT) 6, 7 and a converter. 8 and reactors 9 and 11 and an inverter 10.

A shaft generator (alternating current generator) 22 is mechanically coupled to the propulsion shaft of the ship, and the speed of the propulsion prime mover 21 changes according to the navigation state of the ship, so the output frequency of the shaft generator 22 also changes. fluctuate. However, if the output frequency changes, it is not suitable as a power source for general loads, so it is converted to AC power of a constant frequency and a constant voltage via the power converter 12.

Next, the outline of the operation of the conventional marine shaft power generation system will be described. In FIG. 4, after the output of the shaft generator 22 is converted into direct current through the converter 8, it is converted back into alternating current power of a constant frequency using the separately excited inverter 10. A synchronous phase shifter 24 is provided for the purpose of securing a commutation power source of the separately excited inverter 10 and supplying reactive power to the load. Reference numeral 5 denotes a power conversion control circuit for driving the converter 8 and the thyristor of the inverter 10 to fire. However, in the power converter 12, the converter side is synchronized with the output phase of the shaft generator 22 and the inverter side is synchronized with the output phase of the synchronous phase shifter 24 with the ignition timing of the thyristor of the converter 8 or the inverter 10. The respective PLL circuits 3 and 4 are provided for the purpose. In the power conversion control circuit 5, the voltage detection for knowing the current voltage value is an important control element for keeping the output voltage of the power conversion device 12 constant. This voltage detection is composed of a PT 6 (7) and a voltage detection circuit 1 (2) for detecting an input voltage on the converter side or an output voltage on the inverter side. In the conventional voltage detection, when detecting three-phase voltages as shown in Fig. 5, PT6 (7) is used and the primary side (PS) is delta connection, and the secondary side (SS) is star connection. Is used as.

In FIG. 5, the secondary side (SS) of the PT6 (7) in FIG. 4 is star-connected. The rectifier circuit 31 converts an AC voltage into a DC voltage, and a resistor 32 and a capacitor 33 are connected to each other. The smoothed DC voltage is input to the A / D converter 34, and the N-bit binary signal 35 converted into a digital amount is input to the power conversion control circuit 5 as a voltage detection signal. As for the timing of starting the A / D conversion, the A / D conversion start timing signal 36 is asynchronously output immediately before the binary signal 35 is read from the power conversion control circuit 5.

[0006]

[Problems to be solved by the device]

In the voltage detection circuit configured in this way, the power conversion control circuit 5 is asynchronous and reads at an arbitrary timing. Therefore, if there is ripple fluctuation in the detection voltage, it causes an error in the detected value, and thus a control error in the entire system. After the output E ₀ of the rectifier circuit 31, a smoothing circuit is provided to remove the ripple voltage. The time constant of the smoothing circuit becomes larger as the ripple voltage is reduced, and there is a drawback that the time delay in the smoothing circuit, that is, the control response time becomes longer. In addition, when the frequency and phase of the shaft generator change significantly depending on the navigation state of the ship, such as on the converter side, it is necessary to reduce the ripple voltage as much as possible. There was a disadvantage that the control response time became longer because the time constant of the circuit had to be designed larger.

The present invention has been made in order to solve the above-mentioned drawbacks, and its purpose is to accurately and accurately maintain a main circuit voltage in a steady operating state without significantly changing the conventional circuit configuration of a shaft power generation system. Provide a synchronous voltage detection circuit for a marine shaft power generation system that can convert a binary signal with a short control response time and can detect a ripple voltage value of the detected voltage value without increasing even when the frequency and phase change. Especially.

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention maintains a stable three-phase main circuit voltage of a converter or an inverter connected to a shaft generator driven by a prime mover for ship propulsion. In the detection circuit, an instrument transformer for detecting the three-phase main circuit voltage, a rectifier for three-phase full-wave rectifying the secondary output of the instrument transformer, and converting it to a direct current, and an output of the rectifier for analog・ A / D converter for digital conversion, a phase locked loop circuit for detecting the voltage phase of the secondary output of the instrument transformer, and a timing pulse signal based on a specific value of the counter output of the phase locked loop circuit. And a decoding circuit for generating

[0009]

[Action]

 According to the present invention, for voltage detection in a shaft power generation system, the voltage of the main circuit can be stably converted into a digital amount even if the frequency / phase changes without increasing the time constant of the smooth circuit. .

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. The same components as those of the conventional example of FIGS. 4 and 5 which have already been described are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, reference numeral 20 denotes an input main circuit of a converter or an output main circuit of an inverter, which is a main circuit targeted by the voltage detection circuits 1 and 2. The secondary (SS) output of the voltage transformer for detecting the voltage output from this main circuit has a voltage waveform as shown in Fig. 3 (a). That is, it is input to the three-phase full-wave rectifier circuit 31 and converted into a direct current E _0, which is converted into a binary code digital amount by an A / D converter. The output waveform of the rectifying circuit 31 at this time is a waveform having a period of π / 3 including a ripple component as shown in FIG. 3B.

On the other hand, the PLL circuits 3 and 4 have a circuit configuration as shown in FIG. That is, the three-phase voltage signals u (r), v (s), and w (t) are converted into orthogonal two-phase signals, and the sine component and cosine component are cross-producted to obtain the phase difference Δθ, and the filter PI Is connected to an M-bit counter using a voltage controlled oscillator VCO. The data conversion has a sine and cosine function table, and generates a signal synchronized with the input signal. In the PLL circuits 3 and 4 that continuously compare the phases in this way, the filter PI may have a small time constant and can follow the input voltage phase signal at high speed.

The counters of the PLL circuits 3 and 4 are binary counters, and count 2 ^M during one cycle of the input signal. This count output is decoded by the decoding circuit 37 to decode the phase angle for each cycle of the ripple waveform of FIG. 3B, in this case the count value for every π / 3, and the timing shown in FIG. Get the pulse signal. This phase angle does not change even if the frequency changes, as long as it is within the tracking range of the PLL circuit. If this pulse signal is input to the A / D converter as the timing signal T36 for starting the A / D conversion, the detected voltage value 35 converted into a digital amount with little influence of the error due to the ripple component after rectification can be obtained. .

[0014]

[Effect of device]

 As described above, according to the present invention, the main circuit voltage is detected by PT, and the timing output pulse signal of the voltage detection phase angle is output by the counter output of the PLL circuit for three-phase voltage phase continuous comparison detection and the decoder. Since the generated timing pulse signal is input to the A / D conversion start timing input terminal and the detected voltage value is digitally converted, the smoothing circuit after the rectifier is not required and the delay time in the voltage detection circuit is eliminated. Can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of voltage detection of a shaft power generation system for a ship according to the present invention.

FIG. 2 is a circuit diagram of the PLL circuit of FIG.

3A and 3B are operation waveform diagrams of the present invention, in which FIG. 3A is a waveform diagram of each phase voltage on the secondary side of PT, and FIG. 3B is a rectifier voltage output E.
A DC voltage waveform diagram including a ripple component of ₀ , and FIG. 7C is a counter output waveform diagram of the PLL circuit.

FIG. 4 is a single wire connection diagram of a conventional shaft power generation system for a ship.

5 is a circuit diagram of voltage detection of the shaft power generation system of FIG.

[Explanation of symbols]

1, 2 ... Voltage detection circuit, 3, 4 ... PLL circuit, 5 ... Power conversion control circuit, 6, 7 ... PT, 8 ... Converter, 9 ... D
C reactor, 10 ... Inverter, 11 ... AC reactor, 12 ... Power converter, 21 ... Motor, 22 ... Shaft generator, 23 ... Propeller, 24 ... Synchronous phaser, 25 ... Main circuit breaker, 26 ... Inboard power bus, 32 ... Resistor, 33 ... Capacitor, 34 ... A / D converter, 35 ... Binary signal, 36 ...
A / D conversion start timing signal, 37 ... Decoding circuit.

Claims (1)

[Scope of utility model registration request] 1. A synchronous voltage detection circuit for a marine shaft power generation system, which maintains a stable three-phase main circuit voltage of a converter or an inverter connected to a shaft generator driven by a prime mover for marine vessel propulsion. An instrument transformer for detecting the main circuit voltage, a rectifier for three-phase full-wave rectifying the secondary output of the instrument transformer, and converting it to direct current, and an A / D conversion for analog-digital converting the output of the rectifier. And a phase-locked loop circuit that detects the voltage phase of the secondary output of the instrument transformer, and a decoding circuit that generates a timing pulse signal from a specific value of the counter output of the phase-locked loop circuit. A synchronous voltage detection circuit for a shaft power generation system for a ship, which is characterized in that: