JPS5911268B2 - thyristor conversion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thyristor conversion device, and more particularly to a control and protection device for preventing arm partial commutation failure of a conversion device 10 consisting of an arm constituted by a plurality of thyristors.

Generally, in a thyristor conversion device consisting of an arm configured by connecting a plurality of thyristors in series, during inverter operation, the margin angle decreases by 15% due to fluctuations in power supply voltage, etc., and the turn-off time characteristics of the thyristors connected in series decrease. Partial commutation failure may occur due to variations, and the thyristor may be damaged due to overvoltage when forward voltage is applied.

Details of these phenomena and methods of protecting against them are already known, and are described, for example, in Japanese Patent Publication No. 31015/1983.

Another protection system is a thyristor conversion device as shown in Fig. 1, in which a DC power source E is passed through a DC reactor 1, and a plurality of thyristors are connected in series. This is a so-called separately excited inverter in which power from a DC power source E is converted to an AC system 8 by an inverter configured as follows. 9 is a control device for the inverter; 11 is a detection circuit for detecting the margin angle of arm 1;
Reference numeral 12 denotes a gate circuit, and these 90 detection circuits 11 and gate circuits 12 are provided in the same way for the other arms 2 to 6, but their configurations and functions are the same as those for arm 1, so they are omitted. do.

This detection circuit 11 converts the reverse voltage applied to the arm 1 into a current using a resistor, passes it to a light emitting diode, etc., guides light to a light receiving element on the ground potential side, and can easily isolate and detect the reverse voltage. be. FIG. 2 shows operating waveforms in each part of the conventional device shown in FIG. 1, and FIG.
The difference voltage becomes the inverter DC voltage.

FIG. 2b shows the conduction state of each arm, and FIG. 2c shows the voltage waveform applied to arm 1. In addition, Fig. 2 d shows a pulse with a time width corresponding to the margin angle of arm 1, and Fig. 2 e
indicates the gate firing signal of arm 5. The time is now T. Considering the state in which commutation is performed from arm 1 to arm 3 as shown in Figure 2b, and a reverse voltage is applied to arm 1 until t1 as shown in Figure 2c, this margin angle corresponds to Time T. If the turn-off time of the thyristors in the series-connected arm 1 falls within the variation, partial commutation failure will occur, so at time T, the non-conductor on the conductor P side is turned off as shown in Fig. 2e. The conduction arm 5 is ignited, the current is forcibly commutated from arm 3 to arm 5 as shown in Fig. 2b, and the margin angle of time width T is increased in arm 1 as shown in Fig. 2c. ,
There is a method of turning off all the thyristors in arm 1 to prevent partial commutation failure. This type of protection method is based on the assumption that the margin angle can be detected even for a short period of time, but after the arm firing signal is completed, the current overlap angle increases and the margin angle increases. Considering the case where the margin angle is not detected due to a delay in reverse voltage detection, some thyristors may turn off because the current reduction rate of the thyristor is small, and even if a partial commutation failure has occurred. However, the protective operation did not work and the thyristor was damaged.

The present invention has been made in view of these points, and provides a thyristor conversion device that can protect a thyristor from damage due to partial commutation failure even when a margin angle is not detected. be.

Hereinafter, one embodiment of the present invention will be described in detail based on FIGS. 3 to 5.

FIG. 3 shows the thyristor conversion device according to the present invention in a block configuration, and the difference from the circuit in FIG. A voltage and reverse voltage detection circuit 10 is connected thereto, and a control protection device 90 is provided which operates a gate circuit 12 provided corresponding to the arm 1 in response to a signal from the detection circuit.

Note that the forward voltage and reverse voltage detection circuit 10 and the gate circuit 12 are similarly provided in the other arms 2 to 6, but their configurations and functions are the same as those in arm 1, so a description thereof will be omitted. Further, the control protection device 90 includes a plurality of margin angle protection devices 91 to 96 provided corresponding to the arms 1 to 6, respectively, and a conventional control device 100 that determines the firing sequence of a three-phase bridge, for example. .
Next, to briefly explain the operation of the thyristor conversion device according to the present invention, the signal detected by the forward voltage and reverse voltage detection circuit 10 is supplied to the margin angle protection device 91 and processed.

This margin angle protection device 91 operates in response to an ignition signal from the control device 100 and biases the arm 1 via the gate circuit 12. The same operation is performed for the other arms 2 to 6 by the margin angle protection devices 92 to 96. In this case, the firing start signal to arm 1 becomes the firing completion signal to arm 5 at the same time, but this is because the output terminal 101 of the control device 90 is connected to the terminals 13 and 14 of the margin angle protection devices 91 and 95, respectively. It is understood that it is connected. FIG. 4 specifically shows the circuit configuration of the margin angle protection device shown in FIG. 3. In FIG. 13 is connected to one input terminal of flip-flop 70 via diode 69, and terminal 14, which receives the firing completion signal from output terminal 103 (FIG. 3) of control device 100, is connected to the other input terminal of flip-flop 70. Ru. The output terminal Q of the flip-flop 70 is connected via a conductor 71 to one input terminal of an AND gate 67, and the other input terminal of the AND gate 67 receives reverse voltage detection from the forward voltage reverse voltage circuit 10 (FIG. 3). connected to terminal 16 where the signal is supplied, while AND
The output side of the gate 67 is connected via a conductive wire 73 to a signal level conversion circuit 74, which is further connected to a terminal 15 connected to the gate circuit 12 (FIG. 3). Further, one input terminal of the flip-flop 70 is connected to the terminal 19 (FIG. 3) of the margin angle protection device 91, and the terminal 19 that receives the protection operation signal is connected to the diode 6.
8. Terminal 14 is further connected to one input terminal of flip-flop 89 and to the other input terminal of flip-flop 87, and output terminal Q of flip-flop 89 is connected via conductor 76 to the other input terminal of AND gate 65. be done. The terminal 16 is connected to an inverter 66, the output side of the inverter 66 is connected to one input terminal of an AND gate 65 via a conductor 75, and the output side of the AND gate 65 is further connected to a conductor 77.
The pulse width comparison circuit 82 is connected to the differentiating circuit 78 via the pulse width comparison circuit 82 and to one input terminal of the pulse width comparison circuit 82 . Differential circuit 78
The output side of is connected to a monostable multivibrator 80 via a conductor 79, and the
4 to one input terminal of a flip-flop 87. The output side of the pulse width comparison circuit 82 is connected to one input terminal of the 0R gate 62 via a conductor 83, and the other input terminal of the 0R gate 62 is connected to a conductor 88 on the output side of the output terminal O of the flip-flop 87. Conductive wires 84 on the output side of the AND gate 61 whose input terminals are connected to the terminals 17 to which the forward voltage detection signal from the forward voltage reverse voltage circuit 10 is supplied are connected. Furthermore, 0R gate 62
The output side of is connected to a differentiating circuit 86 via a conductor 85,
The output side of the differentiating circuit 86 is connected to a terminal 18 for generating a margin angle insufficient detection signal, and further connected to the other input terminal of a flip-flop 89 for supplying a reset signal, and is connected to the flip-flop 89 via a diode 63.
Connected to 7. Next, the operation of this margin angle protection device 91 will be explained in detail with reference to the signal waveforms shown in FIG.

In FIG. 5, the earlier time shown on the left side of the drawing is the case where the margin angle was detected, and the later time shown on the right side is the case where no margin angle could be detected. Each number shown in FIG. a-0 corresponds to the number of each part in FIG.

Now, when an ignition start signal as shown in FIG. 5a is supplied from the terminal 13 to one input terminal of the flip-flop 70 through the diode 69, the output at the output terminal Q of the flip-flop 70 is as shown in FIG. 5c. It changes from low level to high level as shown. The reverse voltage detection signal is connected to terminal 16,
When no reverse voltage is applied, it is at a high level as shown in FIG. 5d. The signal from this terminal 16 is supplied to an AND gate 67 together with the output signal of the flip-flop 70, and then converted by a signal level converter 74 to a transmission signal level for the Gefut circuit, and further sent to the gate circuit 12 through the terminal 15.

This signal continues until the firing complete signal is applied to terminal 14. When the ignition completion signal as shown in FIG. 5B is input to the terminal 14, the flip-flop 70 is inverted and its output changes from a high level to a low level as shown in FIG. 5C, and the ignition signal is stopped. The ignition completion signal to the terminal 14 is simultaneously sent to the arm 3 (
3), and commutation from arm 1 to arm 3 occurs. Upon completion of commutation, a reverse voltage is applied to arm 1, and when a reverse voltage detection signal is supplied to terminal 16, the signal as shown in FIG. 5d supplied to AND gate 67 changes from high level to low level. become. The output of the flip-flop 89 operated by the inverted signal shown in FIG. 5e and the firing end signal shown in FIG. 5b becomes a low level as shown in FIG. 5f. This indicates that the reverse voltage signal detected from the time of this change is at the margin angle. The margin angle signal is generated by the reverse voltage signal and the flip-flop 8 shown in FIG. 5e.
By inputting the output of 9 to the AND gate 65, the fifth
This is obtained as a signal as shown in Figure g. At the start of generation of the margin angle signal, differentiation is performed by the differentiation circuit 78 and the fifth
An output as shown in FIG. h is obtained, and this output is supplied to a monostable multivibrator 80 and a flip-flop 87. This differential pulse shown in FIG. 5h operates the monostable multivibrator 80, which is set to the time width shown in FIG. 51, which is the same as the slowest turn-off time of the thyristors connected in series, and If is shorter than this set time, the pulse width comparator circuit 82 is operated to emit pulses corresponding to the shorter period, and pulses corresponding to the shorter period are outputted as shown in FIG. 5J. The flip-flop 87 is
When a margin angle starts to be detected, the output is changed from a high level to a low level as shown in FIG. 5, and when a margin angle is not detected, the output is kept at a high level.
In Fig. 5, the protective operation at an early point in time is when the margin angle is detected and the margin angle is T4 shorter than the set time T3 shown in Figs. A pulse is outputted to the output side of the pulse width comparison circuit 82, this pulse enters the 0R gate 62, and a pulse as shown in FIG. 5n is outputted to the output side thereof. This output is differentiated by a differentiating circuit 86, and a signal as shown in FIG. 50 is outputted from the terminal 18 for entering a protective operation due to insufficient margin angle. After the margin angle is detected, a forward voltage is applied to the arm 1, and a forward voltage detection signal as shown in FIG. 5k is input to the terminal 17. The forward voltage detection signal is always output during the application time of the forward voltage, and becomes a high level output when the forward voltage is applied.
When the margin angle is detected, the output of the flip-flop 87 is at a low level as shown in FIG. The output as shown in is kept at a low level. Furthermore, flip-flops 89 and 87 are reset by a margin angle insufficient detection signal supplied to terminal 18. At the same time, this signal is a protective operation signal. For example, when insufficient margin angle occurs in arm 1, a signal from terminal 18 of margin angle protection device 91 is sent to terminal 19 of margin angle protection device 95 (Fig. 3) of arm 5. This is terminal 1 in Figure 4.
9, the signal passes through the diode 68 and enters the flip-flop 70, changing its output from a low level to a high level as shown in FIG. From the operating gate circuit,
An ignition input is sent, arm 5 is ignited, a reverse voltage is applied to arm 1 as explained in the conventional example, and the application time of the reverse voltage increases as shown in FIG. increases, all thyristors of arm 1 can be turned off, and partial commutation failure can be prevented. If the margin angle is not detected, the flip-flop 87 is activated by the firing completion signal as shown in FIG. At the same time as the forward voltage is detected, the output of the AND gate 61 changes from a low level to a high level as shown in FIG.
Then, a margin angle insufficient detection signal is issued from the terminal 18,
The same margin angle protection operation as described above is performed. Furthermore, flip-flops 87 and 89 are reset by the margin angle insufficient signal. In the above explanation, the protective operation when the margin angle of arm 1 is insufficient was explained, but when arm 2 has insufficient margin angle, arm 6 is fired, when arm 3 is activated, arm 1 is fired, and when arm 4 is activated, arm 1 is activated, and when arm 4 is activated, arm 6 is activated. The protection operation is performed by firing arm 2, firing arm 3 when arm 5 is firing, and firing arm 4 when arm 6 is used, and since these operations are the same, their explanation will be omitted. In addition, in the above-mentioned example,
Although the arm is constructed by connecting a plurality of thyristors in series, it is clear that the present invention is also applicable to cases where the arm is connected in parallel, in series, or in parallel.

Further, in the above embodiment, a thyristor conversion device with a three-phase bridge configuration was described, but a diametral connection,
Needless to say, the present invention can also be applied to a double star-connected thyristor converter. As is clear from the above description, according to the present invention, the forward voltage and reverse voltage of the thyristor arm are detected, and if the margin angle of the thyristor arm is short, the non-conducting thyristor arm is ignited by the reverse voltage to provide margin. If the margin angle is not detected, the non-conducting thyristor arm is fired by the forward voltage to provide the margin angle, and partial commutation failure can be prevented. It is possible to protect the thyristor from damage and obtain a stable thyristor conversion device.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional thyristor conversion device;
1 is a signal waveform diagram for explaining the operation of FIG. 1, FIG. 3 is a circuit configuration diagram showing an embodiment of the present invention, and FIG. 4 is a configuration diagram showing details of the margin angle protection device according to the present invention. , FIG. 5 is a signal waveform diagram for explaining the operation of FIG. 4. In the figure, 1 to 6 are arms, 10 is a forward voltage reverse voltage detection circuit,
12 is a gate circuit, 70, 80, 87, and 89 are flip-flops, 74 is a signal level conversion circuit, 78 and 86 are differentiating circuits, 82 is a pulse width comparison circuit, 90 is a control protection device, and 91 to 96 are margin angle protection devices. , 100 is a control device.

Claims (1)

[Claims] 1. In a thyristor conversion device having at least two thyristor arms, the forward voltage and reverse voltage applied to the thyristor arms are converted into current by a resistor, and this current is applied to each light emitting element for forward and reverse voltage detection. means for guiding the light emission output obtained by passing the light into each light-receiving element for forward and reverse voltage detection and detecting each by the operation of the light-receiving element, and detecting the margin angle of the thyristor arm in response to the output of the detection means, A control that independently comprises means for determining that the margin angle is shorter than a predetermined period and means for determining that the margin angle has not been detected, and that operates a gate circuit provided corresponding to each thyristor arm. and a protection means, in which a pulse intensity comparison circuit is operated to emit a pulse corresponding to the shorter period as a means for determining when the detected margin angle of one of the thyristor arms is shorter than a predetermined period. The other non-conducting thyristor arm is ignited by the reverse voltage to increase the margin angle of the one thyristor arm, and if the margin angle of one thyristor arm is not detected, the output level is changed using a flip-flop and the forward voltage is increased. A thyristor conversion device characterized in that the other non-conducting thyristor arm is ignited to give a margin angle to the one thyristor arm. 2. The thyristor conversion device according to claim 1, wherein the margin angle of the thyristor arm is detected using a termination signal of a firing signal of the thyristor arm and a reverse voltage signal.