JP2936642B2 - Control method of high-speed semiconductor switch circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention always supplies power from a first power supply to a plurality of branch loads, and switches the power supply to a second power supply at high speed when a short circuit occurs. The present invention relates to a method for controlling a semiconductor switch circuit.

B. Summary of the Invention The present invention always supplies power to a plurality of branch loads from a first power supply having a small short-circuit capacity via a first semiconductor switch. 2
In the control method of the high-speed semiconductor switch circuit for flowing a current to the load on the short-circuit occurrence side via the semiconductor switch, when an overcurrent due to a short-circuit accident or the like is detected, an off-control signal is immediately supplied to the first semiconductor switch; By supplying an ON control signal to the second semiconductor switch with a delay of a difference between the OFF time of the first semiconductor switch and the ON time of the second semiconductor switch, the first power supply is switched when the switch is switched. And the second power supply are connected in parallel to prevent a cross current from occurring,
The first semiconductor switch provided on the first power supply side having a small short-circuit capacity does not increase the withstand capability more than necessary.

C. Prior Art Conventionally, a system for supplying power from a power supply having a short circuit capacity such as an uninterruptible power supply to a large number of loads is configured as shown in FIG. 2, for example. In FIG. 2, electromagnetic contactors 3a, 3 are connected to a branch circuit connecting the uninterruptible power supply 1 and a plurality of loads 2a, 2b, 2c.
b and 3c are interposed respectively. In this power supply system, when a short circuit accident occurs in some loads, for example, the load 2c, the uninterruptible power supply 1 stops due to the short circuit current,
Alternatively, the power supply voltage is reduced until the electromagnetic contactor 3c trips, which adversely affects the other loads 2a and 2b. In order to solve such inconvenience, the power supply is switched by a circuit configuration as shown in FIG. 3, for example. That is, a second power supply 4 having a large short-circuit capacity synchronized with the uninterruptible power supply 1 is provided, and the first high-speed semiconductor switches 5a, 5b, 5c are connected to the electric circuit connecting the uninterruptible power supply 1 and the electromagnetic contactors 3a, 3b, 3c. , Respectively, and second high-speed semiconductor switches 6a, 6b, 6c are respectively inserted in the electric paths connecting the second power supply 4 and the electromagnetic contactors 3a, 3b, 3c. In FIG. 3, the second high-speed semiconductor switches 6a, 6b, and 6c are normally turned off, the first high-speed semiconductor switches 5a, 5b, and 5c are turned on. load
Power is supplied to 2a, 2b, 2c. Also some loads, for example load 2c
In the case where a short circuit occurs as shown in FIG.
t ₁₎ in the OFF control of the first high-speed semiconductor switch 5c is turned on controlling the second high-speed semiconductor switch 6c simultaneously. Then, a current flows from the second power supply 4 to the short-circuit fault point on the load 2c side in place of the uninterruptible power supply device 1. Therefore, the electromagnetic contactor 3c trips and only the load 2c is disconnected. Such a power supply switching operation is similarly performed even if a short circuit occurs on the other loads 2a and 2b. Therefore, an excessive current does not flow through the uninterruptible power supply 1 due to the short circuit, and the above-described stop of the power supply and a decrease in the power supply voltage do not occur.

D. Problems to be Solved by the Invention However, in the circuit of FIG. 3, the following problems occur in the semiconductor switches (5a to 5c, 6a to 6c) used. Since the first high-speed semiconductor switches 5a to 5c require a shut-off function, a gate turn-off thyristor or the like is often used, and the high-speed semiconductor switches 5a to 5c are expensive. Further, since the second high-speed semiconductor switches 6a to 6c need to have a withstand capacity, for example, a thyristor is used. Supplying off control signal and on the control signal of the second high-speed semiconductor switch 6c of the first high-speed semiconductor switch 5c as shown at time t ₁ of FIG. 5 Therefore when overcurrent detection time, off-time of the switch 5c ( The time required for turn-off is longer, so the switch 6c
Off completion time t ₃ of the switch 5c but from the time t ₂ which is turned on
The switches 5c and 6c are both turned on in the time until. For this reason, a cross current (a shaded portion in FIG. 5) occurs between the uninterruptible power supply 1 and the second power supply 4. As a result, the responsibility of the first high-speed semiconductor switch 5c (for example, gate turn-off thyristor) is increased, and the withstand capability of the expensive gate turn-off thyrist must be increased more than necessary, which is very disadvantageous economically.

The present invention has been made in view of the above points, and its object is to prevent two power supplies from being connected in parallel,
An object of the present invention is to provide a control method of a high-speed semiconductor switch circuit capable of separating a short-circuit load without unnecessarily increasing the tolerance of an expensive semiconductor switch.

E. Means for Solving the Problems The present invention connects a first power supply comprising an uninterruptible power supply and a plurality of series circuits each comprising a first semiconductor switch comprising a gate turn-off thyristor, an electromagnetic contactor and a load. The output side of a second semiconductor switch composed of a thyristor is connected to a connection point between each of the first semiconductor switches and the electromagnetic contactor, and each of the second semiconductor switches has a short-circuit capacity greater than that of the first power supply. In the semiconductor switch circuit connected to the second power supply, when an overcurrent is detected, an off control signal is supplied to the first semiconductor switch, and the off time of the first semiconductor switch and the second semiconductor switch are substantially reduced from the overcurrent detection time. And supplying an on-control signal to the second semiconductor switch after a lapse of a difference from the on-time of the second semiconductor switch.

F. Operation Normally, power is supplied from the first power supply to the plurality of loads via the first semiconductor switch. When an overcurrent at the time of a short circuit accident is detected, first, an off control signal is supplied to the first semiconductor switch interposed in the short circuit generating side electric circuit. Next, an ON control signal is supplied to the second semiconductor switch after a lapse of time substantially equal to the difference between the OFF time of the first semiconductor switch and the ON time of the second semiconductor switch. Therefore, the second semiconductor switch does not turn on at a time before the turning off of the first semiconductor switch is completed. Next, when the first semiconductor switch is turned off and the second semiconductor switch is turned on,
The short-circuit current flows from the second power supply and is interrupted by, for example, an electromagnetic contactor provided on the short-circuit load side. As a result, the first power supply and the short-circuit load are immediately separated from each other, and the other healthy loads to which the first power supply supplies power are not affected at all. Since the first semiconductor switch and the second semiconductor switch are prevented from being turned on at the same time in this manner, no cross current occurs between the first power supply and the second power supply. For this reason, it is not necessary to increase the tolerance of the first semiconductor switch more than necessary, and the cost of the device can be reduced.

G. Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a time chart when the control method of the present invention is applied to the power supply circuit of FIG. First, the first high-speed semiconductor switches 5a to 5c are always on and the second high-speed semiconductor switches 6a to 6c are off, and power is supplied from the uninterruptible power supply 1 to the loads 2a to 2c. Here is a short circuit accident occurs at the load 2c side, by the current detecting means (not shown) at time t ₁ when detecting an overcurrent, and supplies an OFF control signal to the first high-speed semiconductor switch 5c. At time t ₂ Then the time Td of the difference between the approximately the switch 5c off time and the on time of the switch 6c for has elapsed, supplies the ON control signal to the switch 6c. Then at t ₃ the first
High-speed semiconductor switch turn-off of the 5c is completed at time t ₄ immediately after its turn-on of the second high-speed semiconductor switch 6c completed. It should be noted that between time t ₃ and time t ₄ is a gap,
Both the switches 5c and 6c are turned off. Thus the time t ₃ the load short-circuit current which has been flowing through previous to the switch 5c, the time t ₄ after flowing through the switch 6c.
Therefore, a large short-circuit current flowing from the second power supply 4 through the switch 6c causes the electromagnetic contactor 3c to operate and cut off. As a result, the uninterruptible power supply 1 and the short-circuit load 2c are immediately separated from each other, and the other healthy loads 2a and 2b are not affected at all. As described above, since the switches 5c and 6c are not turned on at the same time, no cross current occurs between the uninterruptible power supply 1 and the second power supply 4. For this reason, the switch 5c does not need to have an increased tolerance more than necessary, which is very economically advantageous. The above operation is performed for the loads 2a and 2b.
The same applies when a short circuit occurs on the side.

H. Effects of the Invention As described above, according to the present invention, an off-control signal is supplied to the first semiconductor switch when an overcurrent is detected, and the off-time of the first semiconductor switch and the off-time of the first semiconductor switch are determined from the overcurrent detection time. Since the ON control signal is supplied to the second semiconductor switch after the lapse of the difference between the ON time of the second semiconductor switch and the second semiconductor switch, the first power supply and the second power supply are not connected in parallel, and Not flowing. Therefore, the responsibility of the first semiconductor switch does not increase. As a result, it is not necessary to increase the tolerance of the first semiconductor switch more than necessary. Therefore, a high-speed semiconductor switch circuit can be configured at low cost.

[Brief description of the drawings]

FIG. 1 is a time chart showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing an example of a conventional power supply device, FIG. 3 is a circuit diagram showing an example of a power supply device provided with a semiconductor switch circuit, FIG. 5 is a time chart showing the outline of the control operation of the circuit of FIG. 3, and FIG. 5 is a time chart showing the details of the control operation of the circuit of FIG. 1 ... uninterruptible power supply, 2a, 2b, 2c ... load, 3a, 3b, 3c ...
... Electromagnetic contactor, 4 ... Second power supply, 5a, 5b, 5c ... First high-speed semiconductor switch, 6a, 6b, 6c ... Second high-speed semiconductor switch.

Claims (1)

(57) [Claims] 1. A first power supply comprising an uninterruptible power supply device, wherein a plurality of first semiconductor switches each comprising a gate turn-off thyristor, a plurality of series circuits each comprising an electromagnetic contactor and a load are connected, and each of said first semiconductor switches is provided. The output side of a second semiconductor switch composed of a thyristor is connected to a connection point between the second semiconductor switch and the electromagnetic contactor, and each of the second semiconductor switches is connected to a second power supply having a short-circuit capacity larger than the first power supply. In the circuit, when an overcurrent is detected, an off control signal is supplied to the first semiconductor switch, and a time corresponding to a difference between an off time of the first semiconductor switch and an on time of the second semiconductor switch from the overcurrent detection time. A control method for a high-speed semiconductor switch circuit, comprising supplying an ON control signal to a second semiconductor switch after a lapse of time.