JPH0457249B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a main circuit system of a bidirectional current-carrying type semiconductor shear breaker using a GTO thyristor.

[Prior art and its problems]

When a GTO thyristor is applied to a semiconductor circuit or circuit breaker, an overvoltage occurs in the GTO thyristor due to the energy stored in the main circuit inductance. To suppress this, an indirect resistor (hereinafter referred to as an arrester) is connected in parallel with the GTO thyristor. There is a limit to the energy consumption per arrester element, and when the energy consumption is large, the arrester elements are connected in parallel to cope with it.

Figure 4 is a conventional connection diagram of a bidirectional conduction type semiconductor circuit breaker using a GTO thyristor. In FIG. 1, 1 is a DC power supply, 2 is an inductance of the power supply, and 3 is a load including the inductance. 4 and 5 are GTO thyristors, and diodes 6 and 7 are connected in antiparallel to each other. both
The GTO thyristors 4 and 5 are connected in series with opposite polarities and inserted into the power supply line between the power source 1 and the load 3. Reference numeral 8 denotes an arrester, which is generally a gear press arrester for voltage limiting and uses a metal oxide non-linear resistor. In addition, a snubber capacitor 4C and a snubber resistor 4R are connected in series, and this snubber resistor 4
A snubber circuit 4S configured by connecting a snubber diode 4D in parallel to R is connected in parallel to the GTO thyristor 4. Similarly, for GTO thyristor 5,
A snubber capacitor 5C and a snubber resistor 5R are connected in series, and a snubber diode 5 is connected to this snubber resistor 5R.
A snubber circuit 5S configured by connecting D in parallel is connected in parallel.

FIG. 5 shows operating waveforms of each part of the cutter shown in FIG. 4, and each horizontal axis is a time axis.

In Fig. 5, A is the load current I ₃ , B is the current I ₄ of the GTO thyristor 4, C is the current I ₈ of the arrester 8,
2 shows an example of the progression of the voltage _V4 of the GTO thyristor 4.

Figure 4 shows the operation of each part of a conventional semiconductor circuit breaker.
This will be explained below with reference to FIG.

Assuming that a short circuit accident occurs on the load side at time t ₀ ,
The current flowing through the disconnector (hereinafter referred to as fault current)
will continue to increase.

A fault current is detected and the GTO thyristor 4 is turned off at time _t1 . The fault current charges the snubber capacitor 4C via the snubber diode 4D. When the electromagnetic energy accumulated in the main circuit inductance is large, the voltage of the snubber capacitor 4C exceeds the limit voltage E _r of the arrester 8, and current starts to flow to the arrester 8, and the fault current I ₃ or the current I ₈ of the arrester 8 becomes I ₃ = I ₈ = I ₀ −E _r −E _d /L ₂ +L ₃ (t−t ₁ (1) (however, i ₃ , i ₅ ≧0). Attenuates as shown below. , I ₀ is the armature current value, L ₂ is the power supply inductance, and L ₃ is the load inductance.

At time _t2 , the arrester 8 consumes the electromagnetic energy of the main circuit inductance, and the shearing is completed. The energy consumption Q of the arrester 8 per cutting operation is expressed as Q=1/2(L ₁ +L ₂ )I ₀ ² E _r /E _r −E ₁ (2).

In this way, the arrester 8 consumes the electromagnetic energy of the load inductance when the arrester 8 operates. Moreover, the energy increases in proportion to the square of the interrupting current.

Therefore, as the load inductance and the shear current increase, the energy consumption of the arrester increases. Since arrester elements generally have a small heat capacity and a maximum allowable temperature of 150° C. or less, the number of parallel arrester elements increases. Therefore, the device becomes larger. There were disadvantages such as the structure of the device becoming complicated and the cost increasing.

[Purpose of the invention]

In view of the above, the present invention provides a bidirectional current-carrying type semiconductor circuit breaker using a GTO thyristor, which reduces the load current interruption time (the time from when the GTO thyristor turns off until the fault current decays to zero). It is an object of the present invention to provide a circuit system that can reduce the energy consumption of an arrester and reduce the number of parallel arrester elements in a practical time.

[Key points of the invention]

According to the present invention, the above object is to connect two sets of anti-parallel circuits each including a gate turn-off thyristor (hereinafter referred to as a GTO thyristor) and a diode in series with opposite polarities, and to connect the series connected body,
In a bidirectional current-carrying type semiconductor circuit breaker, which consists of parallel-connected non-linear resistors to process the energy accumulated in the main circuit inductance and prevent overvoltage of the GTO thyristor, the energy consumption of the non-linear resistors is reduced. However, in order to reduce its size, one end of a series circuit of a freewheeling diode and an attenuation resistor is connected to the common connection point of both antiparallel circuits constituting the series connection body, and the other end of the series circuit is This is achieved by connecting a series circuit in parallel with the load at a point corresponding to the selected load-side terminal.

That is, the present invention attempts to suppress the energy consumption of the arrester by dividing the electromagnetic energy of the load inductance between the arrester and the damping resistor in both directions, and by setting the value of the damping resistor to a value that can be cut off in a practical amount of time. It is something.

[Embodiments of the invention]

FIG. 1 shows a main circuit connection diagram showing an embodiment of a semiconductor shield breaker according to the present invention.

In FIG. 1, 9 is a freewheeling diode, 10 is a damping resistor, and the cathode side of the freewheeling diode 9 is commonly connected to the cathode sides of both GTO thyristors 4 and 5. The anode side of is connected to a load side terminal 11 which is parallel to the load 3 via a damping resistor 10. The rest of the configuration is the same as in FIG. 1.

FIG. 2 shows the operating waveforms of each part of the embodiment shown in FIG. 1, with the time axis plotted on the horizontal axis.

In Figure 2, A is the load current I ₃ , B is the current I ₄ of the GTO thyristor 4, C is the current I ₈ of the arrester 8,
D shows the current I ₉ of the freewheeling diode 9, and E shows the voltage V ₄ of the GTO thyristor 4.

The operation of each part of the embodiment of the semiconductor shield breaker according to the present invention will be explained below with reference to FIGS. 1 and 2.

A short circuit fault occurs on the load side at time t ₀ , and the current flowing through the circuit breaker (hereinafter referred to as fault current) increases.

A fault current is detected and at time _t1 , the GTO thyristor 4 is turned off. The fault current charges the snubber capacitor 4C via the snubber diode 4D. If the electromagnetic energy accumulated in the main circuit inductance is large, the snubber capacitor 4
The voltage of C exceeds the limit voltage E _r of the arrester 8, and the fault current begins to flow in a shunt manner to the arrester 8 and the freewheeling diode 9. Arrester 8 current
I ₈ decreases and the current I ₉ of the freewheeling diode 9 increases.

At time _t2 , the current _I8 of the arrester 8 attenuates to zero. At this time, the current _I9 of the freewheeling diode 9 becomes maximum. At time _t3 , the electromagnetic energy of the main circuit inductance is consumed, and the current _I9 of the freewheeling diode 9 attenuates to zero.
Then the cutting is completed.

FIG. 3 is a graph showing the relationship between the energy consumption Q of the arrester 8 and the damping time T with respect to the value R of the damping resistor 10. As is clear from this, when the damping resistance R is made smaller, the energy consumption Q of the arrester becomes smaller, but the damping time T becomes longer.

Q∽ and T∽ represent the energy consumption and break-down time of the arrester in the case without a freewheeling diode, respectively.

For example, if the damping time is chosen to be T=T ₀ >T∽, the damping resistance becomes R=R ₀ and the energy consumed by the arrester becomes Q=Q ₀ <Q∽. Therefore, the energy consumption of the arrester can be reduced while selecting an appropriate value for the damping time T.

〔Effect of the invention〕

When applying a GTO thyristor to a bidirectional conduction type semiconductor shatterproof switch, a circuit consisting of a GTO thyristor and a diode connected in parallel to the GTO thyristor is connected in series with the polarity reversed, and electromagnetic energy is accumulated in the main circuit inductance. As a result, a conductive voltage is generated in the GTO thyristor when the thyristor is turned off. To suppress it, an arrester is connected in parallel with the GTO thyristor and the series diode. In this case, the arrester consumes all the electromagnetic energy of the main circuit inductance (=power supply inductance + load inductance), so its energy consumption becomes large.

There is a limit to the energy consumption per arrester element, and if the energy consumption is large, the number of arrester elements in parallel increases, but according to the present invention, a freewheeling diode and a freewheeling diode are connected to the cathode side of the GTO thyristor in parallel with the load. By connecting a series circuit of attenuation resistors and appropriately selecting the value of the attenuation resistor, the load current can be cut off in a practical time and the energy consumption of the arrester can be reduced. Also, since the series circuit of the freewheeling diode and the damping resistor is connected to the common connection point of both GTO thyristors, it can be used in both directions. Therefore, the device can be made smaller, simpler, and lower in price. In addition, if a long interruption time can be tolerated as shown in Figure 3, it is possible to use almost zero resistance existing in the circuit without providing a special resistor as a damping resistor, which will reduce the arrester's consumption. Energy can be minimized.

[Brief explanation of the drawing]

FIG. 1 is a main circuit connection diagram of an embodiment of the semiconductor shield breaker according to the present invention, FIG. 2 is an operation waveform diagram of each part of the main circuit of the semiconductor shield breaker according to the present invention shown in FIG. The figure is a graph showing the relationship between the energy consumption of the arrester, the shearing time, and the damping resistance. Figure 4 is a main circuit connection diagram showing an example of a conventional semiconductor shielding circuit breaker. FIG. 3 is an operation waveform diagram of each part of the main circuit of the conventional semiconductor shingle breaker shown in FIG. 1 is the DC power supply, 2 is the inductance of the power supply, 3
is the load, 4 and 5 are resistors, 6 and 7 are diodes, 8
is the arrester, 9 is the freewheeling diode,
10 is a damping resistance.

Claims (1)

[Claims] 1. Each gate turn-off thyristor (hereinafter referred to as
It is called a GTO thyristor. ) and diodes are connected in series with two sets of anti-parallel circuits with opposite polarities, and a non-linear resistor is installed in the series connection to handle the energy accumulated in the main circuit inductance and to prevent overvoltage of the GTO thyristor. In order to reduce the energy consumption of the non-linear resistor and to reduce its size in a bidirectional current-carrying type semiconductor circuit breaker connected in parallel, a common connection point of both antiparallel circuits constituting the series connection body is provided. One end of a series circuit of a freewheeling diode and a damping resistor is connected to the terminal, and the other end of the series circuit is connected to a point corresponding to a terminal on the load side selected so that the series circuit is parallel to the load. A semiconductor circuit breaker characterized by: 2. The semiconductor sheath breaker according to claim 1, wherein the circuit including the freewheeling diode is comprised of a series circuit of a freewheeling diode and a damping resistor.