JP2775947B2 - Load separation interruption method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load separating and interrupting method of a power supply device for supplying power by switching two power sources arranged in parallel to one load without instantaneous interruption.

B. Summary of the Invention The present invention relates to a load separation cut-off method for a power supply device that supplies power to a common load by switching between two power supplies without instantaneous interruption. When an overcurrent flows, the power supply is switched to power supply by the second system power supply by directly using the current, and the overcurrent is attenuated by the second system power supply current. This can be performed instantaneously and reliably, and the overcurrent withstand capability of the first system power supply can be designed to be small.

C. Prior Art Conventionally, a power supply device that switches between two power supplies and supplies power to one load has been configured as shown in FIG. 3, for example. In FIG. 3, reference numeral 1a denotes a power supply device composed of a CVCF (constant voltage / constant frequency device). This power supply device 1a is connected to a load 3 via a semiconductor switch 2a and a first power supply line 11. 1b is a commercial power supply, and this power supply 1b is connected to the load 3 via the semiconductor switch 2b and the second power supply line 12. Normally, the commercial power supply 1b is used as a standby power supply (the semiconductor switch 2b is turned off), and power is supplied from the CVCF power supply device 1a to the load 3 (the semiconductor switch 2a is turned on). When an abnormality such as a failure occurs in the power supply device 1a, the control circuit 5 controls the semiconductor switch 2a to be turned off and the semiconductor switch 2b to be turned on based on the detection current of the current transformer 4 to control the power from the commercial power supply 1b. Switch to power supply. Further, the control power supply excites the coil 6 to turn on the electromagnetic contactor 7 connected in parallel to the semiconductor switch 2b.

D. Problems to be Solved by the Invention In the power supply switching method using the device shown in FIG. 3, since the control circuit 5 issues a switching control command after the current transformer 4 detects an overcurrent, control delay and There is a disadvantage that high-speed and reliable switching cannot be performed due to a control error or the like.

In order to design the CVCF power supply device 1a to have a small overcurrent withstand capability, it is required to suppress the rise of the overcurrent.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a load separation / interruption system capable of instantaneously and surely switching a power supply and capable of designing a power supply withstand small overcurrent. It is in.

E. Means for Solving the Problems The present invention connects a first system power supply to a load via a first semiconductor switch and a first power supply line, and connects a second system power supply to a second semiconductor switch and a second semiconductor switch. Connected to the first power supply line between the first semiconductor switch and the load via two power supply lines,
In a load separating and interrupting method of a power supply device for turning on and off the first and second semiconductor switches to supply power from a first system power supply or a second system power supply to a load,
A second power supply line near a common connection point between the power supply line and the second power supply line,
The current flowing through the first power supply line is wound around the first power supply line in a direction to cancel the current flowing through the first power supply line, and the current flowing through the first power supply line connecting the common connection point of the first power supply line and the second power supply line to the first semiconductor switch. When the detected current is equal to or greater than a predetermined value, the second semiconductor switch is turned on by the detected current, and a current flowing through a first power supply line connecting the common connection point and the first semiconductor switch is detected. To excite the coil of the electromagnetic contactor connected in parallel to the second semiconductor switch.

F. Operation It is assumed that the power supply of the second system is on standby and power is supplied from the power supply of the first system to the load via the first semiconductor switch and the first power supply line. Here, the first
When an overcurrent flows on the power supply side of the system, the detection current of the first power supply line increases. When the detected current becomes equal to or more than a predetermined value, the second semiconductor switch is turned on by the detected current.
Also, the coil of the electromagnetic contactor is excited by the increase of the detection current, and the electromagnetic contactor is turned on. As described above, the second semiconductor switch and the electromagnetic contactor connected in parallel are directly controlled to be turned on by the detection current, so that the power supply can be switched quickly and reliably. Next, when a current flows from the power supply of the second system via the electromagnetic contactor and the second power supply line, the second power supply line is wound around the first power supply line near the common connection point. The current flowing through the wire is canceled out and attenuated. Since the fault current at the time of load short-circuit is suppressed in this way, the overcurrent withstand capability of the first system power supply can be designed to be small, and the power supply device can be economically constructed.

G. Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the same portions as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. Second semiconductor switch 2b
The second power supply line 12 between the first power supply line 11 and the first power supply line 11 is wound around the first power supply line 11 in a coil shape in a direction to cancel the current of the first power supply line 11 near the common connection point a with the first power supply line 11. ing. First
First power supply line 11 between semiconductor switch 2a and common connection point a
Are provided with current transformers 13 and 14, respectively. The output side of the current transformer 13 is connected to the gate of the second semiconductor switch 2b via the level detection circuit 15 and the diode 16. Current transformer
The output side of 14 is connected to the input coil 6 of the electromagnetic contactor. A diode 17 having the illustrated polarity is connected between the control circuit 5 and the gate of the second semiconductor switch 2b. The level detecting circuit 15 is configured as shown in FIG.
In FIG. 2, a capacitor 21 is connected between the output lines of the current transformer 13.
And diodes 22a to 22n connected in series with the illustrated polarity and diodes 23a to 23n connected in series with the opposite polarity to the diodes 22a to 22n are connected in parallel.

In the device configured as described above,
1b to make the first semiconductor switch 2a from the CVCF power supply 1a
It is assumed that power is supplied to the load 3 via the first power supply line 11. Here, when an overcurrent flows from the CVCF power supply device 1a via the first semiconductor switch 2a and the first power supply line 11 due to a load short circuit or the like, the detection current of the current transformers 13 and 14 increases.
When the magnitude of the detection current of the current transformer 13 exceeds a set level determined by the series number of the diodes 22a to 22n and 23a to 23n of the level detection circuit 15, the gate of the second semiconductor switch 2b is turned on via the diode 16. Control current flows. Thereby, the second semiconductor switch 2b is quickly and reliably fired.
On the other hand, the first semiconductor switch 2a is turned on by the control circuit 5. When the current detected by the current transformer 14 increases, the closing coil 6 is excited and the electromagnetic contactor 7 is closed. Therefore, the second semiconductor switch 2b can be rated for a short time. When the power is switched in this way and the current flows from the commercial power supply 1b via the electromagnetic contactor 7, the current flowing through the first power supply line 11 becomes the current of the second power supply line 12 wound around the common connection point a. (Magnetic flux), and is attenuated. As described above, since the fault current at the time of load short-circuit is suppressed, the overcurrent withstand capability of the CVCF power supply device 1a can be designed to be small, and the cost of the device can be reduced.

The set values of the level detection circuit 15 are diodes 22a to 22n,
It can be arbitrarily determined by changing the number of connections of 23a to 23n.

H. Effects of the Invention As described above, according to the present invention, the following excellent effects can be obtained.

(1) When the detection level of the overcurrent flowing in the first power supply line is equal to or higher than a predetermined value, the second semiconductor switch is directly turned on by the detection current, so that the power supply can be quickly and reliably switched.

(2) Since the coil of the electromagnetic contactor is directly excited by the detection current of the first power supply line, not only is the closing of the electromagnetic contactor reliable, but also the more the detection current increases due to overcurrent, the more the biasing force becomes. It becomes stronger (the throwing power increases in proportion to the square of the current from the theoretical LI ² of the electromagnetic force of the coil) and is injected in a shorter time.

(3) The second power supply line is wound in a coil shape around the first power supply line, and the first power supply line current is suppressed by the second power supply line current. The current can be suppressed.

(4) Due to the effect of the above item (3), the first power supply line side first
A system power supply, for example, a CVCF power supply, can be constructed economically.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram of a main part of the embodiment, and FIG. 3 is a circuit diagram showing an example of a conventional device. 1a: CVCF power supply device, 1b: commercial power supply, 2a: first semiconductor switch, 2b: second semiconductor switch, 3: load, 5: control circuit, 6: closing coil, 7: electromagnetic contactor, 11: first power supply Electric wire, 12: second power supply line, 13, 14, current transformer, 15: level detection circuit, 16, 17, 22a to 22n, 23a to 23n: diode, 21: capacitor.

Claims (1)

(57) [Claims] A first power supply connected to a load via a first semiconductor switch and a first power supply line; and a second power supply connected to the load via a second semiconductor switch and a second power supply line. 1 connected to a first feeder line between the semiconductor switch and the load,
In a load separating and interrupting method of a power supply device for supplying power from a first system power supply or a second system power supply to a load by controlling on / off of the first and second semiconductor switches, the first power supply line and the second power supply A second power supply line near a common connection point of the electric wires is wound around the first power supply line in a direction to cancel a current flowing through the first power supply line, and the common connection point of the first power supply line and the second power supply line is connected to the second power supply line. Detecting a current flowing through a first power supply line connecting the first semiconductor switch and, when the detected current is equal to or more than a predetermined value, controlling a second semiconductor switch to be on according to the detected current; 1. A load separating and interrupting method, wherein a current flowing through one power supply line is detected, and a coil of an electromagnetic contactor connected in parallel to a second semiconductor switch is excited by the detected current.