JPH0557769B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bidirectional conduction type semiconductor circuit breaker equipped with an anti-parallel GTO thyristor formed by connecting two reverse blocking GTO thyristors in anti-parallel to each other.

[Conventional technology]

In a bidirectional current-carrying circuit breaker using a reverse-blocking GTO thyristor (hereinafter simply referred to as a GTO thyristor), if a reverse voltage is applied to the GTO thyristor when the gate forward current is flowing, a large reverse leakage current will flow, resulting in a very large Element loss occurs, partially heating the GTO thyristor, and depending on how long the reverse voltage is applied, there is a risk of destruction. To avoid this, two GTOs connected anti-parallel to each other
By simultaneously turning the thyristors on and off (turning them on and off at the same time) using a common gate signal, the time period during which a reverse voltage is applied between the anode and cathode of the GTO thyristor with forward gate current applied can be reduced.
It is necessary to increase the reliability of the GTO thyristor by keeping it to less than a few μs, which corresponds to the turn-on time t _gt of the GTO thyristor (however, the gate signals must be isolated from each other).

FIG. 7 is a conventional main circuit connection diagram of a bidirectional conduction type circuit breaker in which two GTO thyristors are connected in antiparallel. In this figure, 1 is a DC power supply, 2 is a power inductance, 3 and 4 are GTO thyristors, and 5
is the load including inductance. P ₀ and P ₁ are the main circuit terminals of this semiconductor circuit breaker.

Reactors 3L and 4L are connected in series to the GTO thyristors 3 and 4, respectively. Furthermore, a snubber capacitor 3C and a snubber resistor 3R are connected in series,
A snubber circuit 3S configured by connecting the snubber resistor 3R and a snubber diode 3D in parallel is connected to the GTO thyristor 3. Similarly, the GTO thyristor has a snubber capacitor of 4C and a snubber resistor of 4C.
Snubber circuit 4 consisting of R, snubber diode 4D
C are connected in parallel.

3Z and 4Z are voltage-dependent nonlinear resistors (hereinafter referred to as arresters) made of a metal oxide system such as a ZnO arrester, and when the load current is interrupted, the inductance of the load 5, the power supply inductance 2,
This prevents overvoltage from being applied to the GTO thyristors 3 and 4 due to overcharging of the snubber capacitors 3C and 4C due to the energy stored in the reactors 3L and 4L, and at the same time prevents the energy stored in the circuit inductance from being applied. This helps absorb the load current and quickly attenuate the load current.

As shown in Figure 8, anti-parallel connection
When using multiple GTO thyristors in combination, the reactor connected in series to each GTO thyristor as described above plays the role of a current balance reactor to suppress transient current imbalance (Figure 8 shows a snubber circuit). connections are omitted).

9a to 9i are operation waveform diagrams of each part of the bidirectional conduction type semiconductor circuit breaker of FIG. 7 at the time of closing, and the horizontal axis is the time axis. In this figure, a is the turn-on signal of the GTO thyristors 3 and 4, b and c are the currents I ₃ and I 4 of the GTO thyristors 3 and ₄ , d and e are the current I _C3 of the snubber capacitor 3C, the voltage U _C3 , f, g indicates the current I _C4 and voltage U _C4 of the snubber capacitor 4C, and h and i indicate the currents I _R3 and I _R4 of the snubber resistors 3R and 4R.

With reference to FIG. 9, the operation of the conventional bidirectional conduction type semiconductor circuit breaker shown in FIG. 7 will be explained.

At time t ₀ , GTO thyristors 3 and 4 are in the off state, and snubber capacitors 3C and 4C are in the 7th
It is charged to the DC power supply voltage E with the polarity shown in the figure [see Figure 9 e and g].

As can be seen from Figure 9a, at time t ₁ both GTO
On signals are applied to the gates of thyristors 3 and 4 at the same time. At this point, the GTO thyristor 3 that matches the voltage polarity between the main terminals P ₀ and P ₁ turns on.
After the turn-on time t _gt , the anode-cathode voltage of the GTO thyristor 3 attenuates to zero. Therefore, a reverse voltage is applied to the GTO thyristor 4 in the reverse direction while the forward gate current flows for a short period of time t _gt . When the GTO thyristor 3 turns on, a discharge current flows from the snubber capacitor 4C of the GTO thyristor 4 in the opposite direction to the GTO thyristor 3 through the snubber diode 4D and the reactors 4L and 3L [Fig. 9 b, f
reference〕. An LC resonance circuit composed of reactors 4L, 3L and snubber capacitor 4C,
The peak current is suppressed.

On the other hand, since the snubber capacitor 3C is discharged through the snubber resistor 3R, the discharge current attenuates with a time constant determined by the capacitance value of the capacitor 3C and the resistance value of the resistor 3R (see FIGS. 9d and 9h).

At time _t2 , the discharge current of the snubber capacitor 4C reaches the peak value _IP . At the same time, the voltage of the snubber capacitor 4C becomes zero (see FIG. 9 f, g).
When time passes time t ₂ , snubber capacitor 4
Since the voltage on C goes from zero to positive, GTO in the opposite direction
Thyristor 4 becomes conductive [see Figure 9 c], and the current in reactors 3L and 4L begins to circulate through the path of reactor 4L → reactor 3L → GTO thyristor 3 → GTO thyristor 4 [see Figure 9 f, b, c] ].

At time _t3 , the discharge current from the snubber capacitor 3C attenuates to zero, completing the turn-off operation of the GTO thyristor 3.

Even at this point, the currents in the reactors 3L and 4L continue to circulate (although they are attenuated somewhat due to voltage drops such as the on-voltage of the GTO thyristor, the time constant is very long).

Here, if the load current is i _L , the current flowing through the GTO thyristor 3 is I ₃ = I _P + i _L /2,
The freewheeling current is superimposed on the load current (the current flowing through the GTO thyristor 4 is I ₄ = I _P −i _L /
2).

[Problem that the invention seeks to solve]

Therefore, the conventional technology has the following problems.

(1) If the interrupting operation is started at this point, the GTO thyristor 3 has to interrupt an extra amount of the return current I _P , so the value of the load current that the circuit breaker can interrupt decreases (the GTO thyristor has a maximum controllable current (It will be destroyed if the current exceeding the current is interrupted).

Note that the peak value I _P of the discharge current of the snubber capacitor 4C is expressed as I _P = _E√4 ( ₃ + ₄ ). However, C ₄ is the capacitance of the capacitor 4C, L ₃ and L ₄ are the inductance values of the reactors 3L and 4L, and E is the charging voltage of the capacitor 4C.

(2) When trying to suppress the return current I _P , reactor 3
The inductance values L ₃ and L ₄ of L and 4L must be increased, which increases the size of the reactor and the size of the device.

(3) If you try to use reactors 3L and 4L without increasing their inductance values, you will have to wait for the freewheeling current I _P to decay naturally (minor attenuation due to a voltage drop such as the on-voltage of the GTO thyristor), and the circuit breaker Closing and shutting operations are subject to time constraints (after the closing operation, the shutoff operation is executed after waiting for the return current I _P to decay to an appropriate value).

Therefore, an object of the present invention is to use two GTO thyristors connected in antiparallel to turn on and off both GTO thyristors at the same time. The object of the present invention is to prevent the return current and thereby solve the problems in the conventional techniques described above.

[Means for solving problems]

The above object, according to the invention, is achieved by two reverse blocking
Anti-parallel made by connecting GTO thyristors in anti-parallel
In a bidirectional conductive semiconductor circuit breaker equipped with a GTO thyristor, the anti-parallel GTO thyristor consists of two reverse-blocking GTO thyristors that are directly connected in anti-parallel and are controlled to turn on and off at the same time, and both ends of the anti-parallel GTO thyristor is connected to the AC side terminal of the diode bridge, and a snubber capacitor is connected between the DC side terminals of the diode bridge to configure a snubber circuit for the anti-parallel GTO thyristor, and to the snubber capacitor, By connecting in parallel a discharge semiconductor switch that is turned on according to the on signal of the anti-parallel GTO thyristor through a diode and a resistor whose polarity is in the direction in which the discharge current of the capacitor flows, the snubber capacitor is This is achieved by configuring a discharge circuit.

In that case, when multiple sets of parallel connection circuits of anti-parallel GTO thyristors and snubber circuits are connected in parallel, multiple sets of parallel connection circuits are connected in series with current balance reactors, and then connected in parallel with each other, It is preferable that the discharge semiconductor switch is shared by all parallel connected circuits.

Further, it is preferable to connect a voltage-dependent nonlinear resistor for overvoltage absorption in parallel to each of the anti-parallel GTO thyristors.

[Effect]

According to the solution according to the invention, even if both GTO thyristors are turned on simultaneously when the circuit breaker is closed, the snubber capacitor is prevented from discharging through the GTO thyristor by the diode of the diode bridge. Instead, the snubber capacitor is discharged through the semiconductor discharge switch and the diode and resistor by the conduction of the semiconductor discharge switch. Therefore, since no return current occurs as in the prior art, problems caused by return current are solved.

〔Example〕

FIG. 1 is a main circuit connection diagram showing an embodiment of the present invention.

In FIG. 1, 1 is a DC power supply, 2 is a power supply inductance, 31, 41, 32, 42 are GTO thyristors, and 5 is a load including inductance. GTO thyristors 31 and 41 are directly connected in antiparallel. The GTO thyristors 32 and 42 are also directly connected in antiparallel.

A common balance reactor 211 is connected in series to the GTO thyristors 31 and 41. Further, a bridge-type snubber circuit 201 composed of diodes 71, 81, 91, 101 and a capacitor 61 is connected in parallel to the GTO thyristors 31, 41. Further, an arrester 111 is connected in parallel to the GTO thyristors 31, 41 for energy processing of circuit inductance and for preventing overvoltage of the GTO thyristors 31, 41.

Similarly, a balance reactor 212 is connected in series to the GTO thyristors 32 and 42,
A snubber circuit 202 composed of diodes 72, 82, 92, 102 and a capacitor 62 and an arrester 112 are connected in parallel to the GTO thyristors 32, 42.

A positive terminal and a negative terminal of each snubber capacitor 61 and 62 are connected to the discharge circuit 22, respectively. The discharge circuit 22 is a diode 12
1, 122, 141, 142 and resistors 131, 13
2,151,152 and a GTO thyristor 16. The anode of the GTO thyristor 16 is connected to the positive terminal of the capacitor 61 through a series circuit of a diode 121 and a resistor 131 on the one hand, and the positive terminal of the capacitor 62 through a series circuit of a diode 122 and a resistor 132 on the other hand. side terminal is connected. The cathode of the GTO thyristor 16 is connected to the negative terminal of the capacitor 61 via the resistor 151 and the diode 141 on the one hand, and to the negative terminal of the capacitor 61 via the resistor 151 and the diode 141 on the other hand. GTO thyristor 16 has 17 diodes, 18 capacitors, and 1 resistor.
The RCD snubber circuit 20 is comprised of 9 RCD snubber circuits.
The GTO thyristor 1 therefore serves as a switch in the discharge circuit for the capacitors 61, 62.
6 acts simultaneously on the GTO thyristors 31, 41, 32, and 42.

Next, with reference to FIGS. 2, 3, and 4, the operation of the bidirectional conduction type semiconductor breaker shown in FIG. 1 according to the embodiment of the present invention will be described.

FIG. 2 is a waveform chart showing the operation of each part when the circuit breaker is closed. First, the circuit breaker closing operation will be explained with reference to this diagram. In Fig. 2, a is the circuit breaker closing command, and b is the current I ₃₁ of the GTO thyristor 31.
(or current I ₃₂ of GTO thyristor 32), c is current I 61 of snubber capacitor ₆₁ (or current I 62 of snubber capacitor ₆₂ ), d is voltage U ₆₁ of snubber capacitor 61 (or current I 62 of snubber capacitor 62),
2 voltage U ₆₂ ), e is the current balance reactor 2
11 current I ₂₁₁ , f is current balance reactor 2
12 current I ₂₁₂ , g is the current of GTO thyristor 16
I ₁₆ , h indicates the current I ₁₈ of the snubber capacitor 18, and i indicates the waveform of the voltage U ₁₈ of the snubber capacitor 18.

At time t ₀ , GTO thyristors 31, 32,
41, 42, and 16 are in an off state, and snubber capacitors 61, 62, and 18 are charged to DC power supply voltage E with the polarities shown in FIG.

In such a state, as shown in Figure 2a,
A circuit breaker closing command is given at time _t1 . With this closing command, an ON signal is given not only to the GTO thyristors 31 and 32 in the forward polarity but also to the GTO thyristors 41 and 42 in the reverse direction (this is because the GTO thyristors 31 and 42 are turned on due to the intermittent load current).
This is to prevent a reverse voltage from being applied to 32). Furthermore, at the same time, an on signal is also applied to the gate of the GTO thyristor 16 in the discharge circuit 22. Therefore, FIG. 2a shows the ON signals of all GTO thyristors.

At time t ₁ , the GTO thyristors 31 and 32 with forward polarity with respect to the voltage between the main terminals P ₀ and P ₁ are turned on, and after turn-on time t _gt their anode-cathode voltage decays to zero. . Therefore, the period during which the reverse voltage is applied to the GTO thyristors 41 and 42 in the reverse direction while receiving the gate-on current is only this turn-on time t _gt
It is between. By turning on the GTO thyristors 31 and 32, the power supply 1 is connected to the reactor 21.
1 and the GTO thyristor 31 and a path via the reactor 212 and the GTO thyristor 32, and the current begins to flow to the load 5.
This load current i _L rises almost linearly (see Figures 2b and 2e). Furthermore, due to the turn-on of the GTO thyristor 16 of the discharge circuit 22 at time _t1 , the capacitor 61 → diode 121 → resistor 1
The snubber capacitor 61 is discharged along the path 31→GTO thyristor 16→resistance 151→diode 141→capacitor 61 with a time constant determined by the resistors 131, 151 and the capacitor 61 [see FIGS. 2c and d]. Similarly, capacitor 62→
The snubber capacitor 62 is discharged along the path of diode 122 → resistor 132 → GTO thyristor 16 → resistor 152 → diode 142 → capacitor 62 with a time constant determined by resistors 131, 151 and capacitor 61 [see Figure 2 c, d] ]. At the same time, the snubber capacitor 18 is also discharged along the path of capacitor 18 → resistor 19 → GTO thyristor 16 → capacitor 18 with a time constant determined by resistor 19 and capacitor 18 [Fig. 2 g to i
reference〕. In this case, the charges on snubber capacitors 61 and 62 are transferred to diodes 71, 81, 91, 101 and 72, 82, 9, respectively.
GTO thyristor 31 blocked by 2,102,
41 is not discharged.

At time _t2 , the discharge currents of the snubber capacitors 61, 62 and 18 become zero, their voltages become zero, and the closing operation of the circuit breaker is completed.

Therefore, according to the present invention, unlike in the conventional device, no circulating current flows, so that the breaking ability of the circuit breaker does not deteriorate due to such circulating current.

In the present invention, the on-gate signal is applied continuously to the GTO thyristor 16, but only during the time when the snubber capacitors 61 and 62 are sufficiently discharged.
A method of providing an on-gate signal to the GTO thyristor 16 may also be used.

Next, referring to FIG. 3, the operation at the time of interruption will be explained. In Fig. 3, a is the interrupting command of the circuit breaker, b is the current I ₃₁ of the GTO thyristor 31, c,
d is the current I ₆₁ of the snubber capacitor 61, the voltage U ₆₁ ,
e is the current I ₃₂ of the GTO thyristor 32, f and g are the current I ₆₂ and voltage U ₆₂ of the snubber capacitor 62, h is the current I ₁₁₁ of the arrester 111, and i is the electric arrester 112.
The current I ₁₁₂ , j is the current I ₁₈ of the capacitor 18, and k is the waveform of the voltage U ₁₈ of the capacitor 18.

It is assumed that the gate turn-off times of the GTO thyristors 31, 32, and 16 are t _G31 and t _G32 , respectively, and that t _G31 <t _G32 due to variations in the turn-off times of the elements.

At time t ₀ , the GTO thyristors 31 and 32 are in a conductive state, and the snubber capacitors 61, 62, 18
The voltage at is zero.

As shown in FIG. _3a , the GTO thyristors 31, 32, 16 are
A turn-off signal is simultaneously applied to the gates of the two.
At the same time, GTO thyristor 41,4 in the opposite direction
A turn-off signal is also given to the gate of No.2. Immediately before this, it is assumed that the GTO thyristors 31 and 32 are in a conductive state, the currents flowing through each GTO thyristor 31 and 32 are equal, and I ₃₁ =I ₃₂ =I _L /2. However, I _L represents the current of the load 5.

When the turn-off time t _G31 of the GTO thyristor 31 has elapsed from time t ₁ to time t ₂ , the GTO thyristor 31 is turned off. As can be seen from Figure 3 b and c, until then the GTO thyristor 31
The current flowing through the snubber capacitor 61 flows into the snubber capacitor 61 through the path of the diode 71→snubber capacitor 61→diode 81, and the voltage U ₆₁ of the snubber capacitor 61 begins to rise as shown in FIG. 3d. The current flowing into the snubber capacitor 61 is attenuated into a resonant current waveform determined by the inductance L of the current balance reactors 211 and 212 and the capacitance C of the snubber capacitor 61.
The current flowing through the GTO thyristor 32 increases by that amount, but the current balance reactor 211, 21
2 [see Fig. 3 c, f].

At time _t3, when the turn-off time _tG32 of the GTO thyristor 62 has elapsed from time _t1 , the GTO thyristor 32 is turned off. GTO thyristor 3
2 turns off, the current flowing through the GTO thyristor 32 flows into the snubber capacitor 62, as shown in Fig. 3e and f, and the voltage U ₆₂ of the snubber capacitor 62 rises as shown in Fig. 3g. go.

At time _t4 , the voltage of the snubber capacitor 61 exceeds the limit voltage Er of the arrester 111. As a result, as can be seen from Fig. 3c, the current flowing through the snubber capacitor 61 is commutated to the arrester 111, and the maximum voltage of the GTO thyristor 31 is increased as shown in Fig. 3d.
As shown in , the voltage is suppressed to the arrester limit voltage Er.

At time _t5 , the voltage of the snubber capacitor 62 of the GTO thyristor 32 also exceeds the limit voltage Er of the arrester 112. As a result, as can be seen from FIG. 3f, the current flowing through the snubber capacitor 62 is commutated to the arrester 112, so
The maximum voltage of the thyristor 32 is suppressed to the limit voltage Er by the arrester, as shown in FIG. 3g.

On the other hand, after the GTO thyristor 31 is turned off at time _t2 , the diodes 121, 17, and 141 become conductive as the voltage of the snubber capacitor 61 increases, so that a part of the load current is transferred from the diode 121 to the resistor 131 to the diode. 17→snubber capacitor 18→resistance 151→diode 141, and flows into the snubber capacitor 18. Further, after the GTO thyristor 32 is turned off at time t ₃ , the voltage of the snubber capacitor 62 increases and the diodes 122 and 142 also become conductive.
A portion of the load current also flows into the snubber capacitor 18 through the path 42. In this way, the snubber capacitor 18 is charged until its voltage U ₁₈ reaches the arrester limit voltage Er [Fig. 3j,
See k].

Thereafter, the electromagnetic energy stored in the inductance of the load is consumed by the arresters 111 and 112, the load current is attenuated to zero, and the interrupting operation is completed. Load current interruption in the reverse direction can also be interrupted by the GTO thyristors 41 and 42 in the same manner.

Diodes 121, 122, 1 of discharge circuit 22
41 and 142 are mounted to avoid interference between snubber capacitors 61 and 62. Further, the discharge resistors 131 and 151 are divided into the plus and minus sides of the snubber capacitor 61, and braking is applied by the resistors to achieve this effect.

4, 5, and 6 show different modifications of the discharge circuit 22 in the embodiment of the present invention according to FIG. 1. Figure 4 shows the diode 14 in Figure 1.
1, 142, a circuit in which resistors 151, 152 are omitted, FIG. 5 shows the diodes 141, 142 in FIG. 1.
The circuit shown in FIG. 6 is the one in which the resistor 151 in FIG. 1 is omitted.
This is a circuit in which 152 is omitted.

〔effect〕

When using a reverse blocking type GTO thyristor, if a reverse voltage is applied to the GTO thyristor when the gate forward current is applied, a large reverse leakage current will flow and a very large loss will occur, partially heating the GTO thyristor and destroying it. Exposure to such conditions should be avoided as there is a risk of this happening. Therefore, in a bidirectional conduction type semiconductor circuit breaker using reverse blocking GTO thyristors connected in antiparallel, this is prevented by simultaneously turning on and off the forward and reverse GTO thyristors using a common gate signal.

However, in conventional circuit devices, when the forward and reverse GTO thyristors are fired at the same time, the discharge current of the snubber capacitor in the opposite direction circulates between the forward and reverse GTO thyristors, reducing the load current value that can be interrupted by the circuit breaker. There was a problem in that it was not possible to quickly turn on and off.

According to the present invention, even if two reverse blocking GTO thyristors are used in antiparallel combination and both GTO thyristors are extinguished at the same time, no return current is generated unlike in conventional devices, so the circuit breaker can be tripped. Therefore, the load current value does not drop, and quick turn-on and cut-off operations can be performed.

In addition, the snubber capacitor, arrester, and balance reactor can be shared between forward and reverse GTO thyristors, making it possible to downsize the device.

Furthermore, since a discharge circuit can be shared among a plurality of sequential and reverse GTO thyristors connected in parallel, it is possible to downsize the device. This becomes more effective as the number of parallel operations increases. Furthermore, since the gates of the forward and reverse GTO thyristors and the discharge circuit GTO thyristor can be extinguished at the same time, they can be turned on and off based on a common signal, improving reliability without requiring complicated control.

Another advantage is that the forward and reverse GTO thyristors can be mounted on a common cooling body, making it possible to further downsize the device.

It is not necessary that the number of forward and reverse GTO thyristors be the same in the circuit breaker as a whole.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a bidirectional conduction type semiconductor circuit breaker according to the present invention, FIGS. 2 and 3 are operation waveform diagrams of each part to explain the embodiment of FIG. 1, and FIGS. Fig. 6 is a circuit diagram showing different modifications of the discharge circuit portion of the embodiment shown in Fig. 1, Fig. 7 is a circuit diagram showing an embodiment of a conventional bidirectional conduction type semiconductor circuit breaker, and Fig. 8 is a reverse circuit diagram. parallel
A circuit diagram showing an embodiment of a conventional bidirectional current-carrying type semiconductor circuit breaker formed by connecting multiple sets of GTO thyristors in parallel; FIG. It is a waveform diagram of each part operation. 1... Power source, 5... Load, 16... Semiconductor switch for discharge, 31, 41... Anti-parallel GTO thyristor, 32, 42... Anti-parallel GTO thyristor,
71, 81, 91, 101... diode bridge, 72, 82, 92, 102... diode bridge, 61, 62... snubber capacitor.

[Claims]

1(a) first, second and third inputs each having at least a first, second and third input and first and second outputs each independently connected to a power source so as to provide the same logical output; (b) a first output of the first logic gate circuit;
a first direct connection means between a first input of said third logic gate circuit; (c) a second output of said first logic gate circuit;
a second direct connection means between a first input of said fourth logic gate circuit; (d) a first output of said second logic gate circuit;
third direct connection means between a second input of said third logic gate circuit; (e) a second output of said second logic gate circuit;
a fourth direct connection means between a second input of said fourth logic gate circuit; (f) a first output of said third logic gate circuit;

Claims (1)

2. A plurality of sets of parallel circuits of the anti-parallel GTO thyristor and the snubber circuit are connected in parallel with each other with current balance reactors connected in series, and the discharge semiconductor switch is shared by each of the parallel circuits. A bidirectional conduction type semiconductor circuit breaker according to claim 1, characterized in that: 3. The bidirectional conduction type semiconductor according to claim 1 or 2, wherein each of the anti-parallel GTO thyristors is provided with a voltage-dependent nonlinear resistor for overvoltage absorption that is connected in parallel with each other. circuit breaker.