JPS58212318A - Shortcircuit protecting system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field of the invention The present invention relates to a short-circuit protection method for a power supply, and in particular to the adverse effects on an external circuit when one switching element of a switching power supply operating in parallel causes a short-circuit accident. This is so that you can avoid this.

(2) Background of the Technology Switching power supplies using switching elements such as transistors are widely used in data processing devices and the like because of their low heat generation and high efficiency. Recently, data processing equipment has become larger and the number of ICs and L8Is that make up the data processing equipment has increased in order to perform complex data processing, and as a result, the power supply for the data processing equipment has also become large in capacity with low voltage and large current. It's here.

However, transistors normally used as switching elements have a limited switching capacity, and when constructing a large-capacity power supply, it is necessary to use a plurality of switching power supplies connected in parallel.

(3) Prior art and problems Therefore, when constructing a large capacity switching power supply,
For example, as shown in FIG. 1, the output of an AC power supply 1 is smoothed by a diode 3 and a capacitor 4 via a no-fuse breaker 2, and the capacitor 4 has a
Switching power supplies 8WR-1 and 8WR- are connected via a diode 5.6 for backflow prevention and a capacitor 7.8 for instantaneous interruption.
2 are connected in parallel and these switching power supplies 8WR-1
, aWR-2 is configured to supply the output of the load LOD.

Here, the switching power supply 5WR-1 is a transformer T-1,
Diode DI-1% diode D21. It is composed of D3-i, an inductance L-1, a capacitor C-1, a switching transistor Tr-, a pulse oscillator PG-1, and the like. Turn on and off the transformer T.
The DC voltage supplied by the capacitor 7 to the primary winding of the transformer T-1 is turned on and off, and the voltage generated in the secondary winding of the transformer T-1 is rectified by the diode D2-1, and the inductance L -1, DC is supplied to the load LOD' after smoothing with the capacitor bow c-1. Furthermore, diode D! -1 is the transistor T
When y-1 is off, it acts as an absorber to absorb the back electromotive force generated in the primary winding of transformer T-1, and D3-
1 is a commutation diode. The switching power supply 5WR-2 is also configured in the same manner as the switching power supply 19WR-1.

When the switching power supplies 5WR-1 and 8WR-2 are operated redundantly in parallel to supply power to the load LOD, if a short circuit occurs in the transistor T7-2, the output side of the diode 6 will be short-circuited, and the same AC power source 1 will be connected to the output side of the diode 6. If the input side of the supplied switching power source 5WR-2 is short-circuited, this will have an adverse effect that both devices will not be able to operate normally. Therefore, such a switching transistor Tr.

It is necessary to detect the short-circuit destructive state of 'r, 2. For this purpose, connect current transformers CT to the switching power supplies 8WR-1 and 8WR-2 as shown by dotted lines to detect overcurrent in the short-circuit state. Detect and protect against short circuits using no-fuse breaker 2 or fuses.
11. However, these protection measures have the following drawbacks:

■ When using a current transformer, as shown in Figure 2, the output current of the current transformer CT is rectified by a diode D and led to an integrating circuit consisting of a resistor R and a capacitor C, and the terminal voltage of the capacitor C is is monitored by the detection circuit 9. The short-circuit current that flows when a switching element such as a transistor breaks down in short-circuit mode is detected by the rise in terminal voltage of capacitor C, but since an integrating circuit is used, the response speed is delayed. Become.

■ When using a No. 1 fuse breaker or fuse, the response is even slower than in (2) above, making it difficult to prevent interference with other circuits. Moreover, in the case of parallel redundant operation, if a no-fuse breaker or fuse is provided in common, both systems will be turned off by the breaking operation.

(4) Purpose of the Invention The purpose of the present invention is to immediately detect a short-circuit accident in a switching element or a control element, and to
It is an object of the present invention to provide a short-circuit protection method that suppresses the current flowing into the switching element or control element in this short-circuited state.

(5) Features of the Invention In order to accomplish this purpose, the short circuit protection method of the present invention includes:
In a power supply equipped with a switching element for controlling on/off of the source voltage or a control element for controlling the current, and a supply means for supplying the output of the switching element or control element to a load, the power source is connected in series to the switching element or control element. and a short-circuit state detection means for detecting a short-circuit state of the switching element, and the output of the short-circuit state detection means controls the current control means to control the current flow to the switching element when the switching element is short-circuited. The feature is that the flowing current is controlled.

(6) Embodiment of the Invention An embodiment of the present invention will be described based on FIGS. 3 and 4.

FIG. 3 is a block diagram showing an example of a switching power supply configured according to the present invention, and FIG. 4 is a specific circuit configuration diagram thereof.

In the figure, 10 is a control circuit, 11 is a transformer circuit, 12 is a switch, a switching element, 13 Fi oscillator, 14 is a rectifying and smoothing circuit, and 15 is a detector.

The control circuit 10 suppresses the current flowing through the switching element 12 when the switching element 12 is short-circuited and destroyed, and includes, for example, transistors T, -.

The transformer circuit 11 is for generating blood flow power to be supplied to the load, and is equipped with a diode D1 for the transformer T1 amplifier, etc., and the primary winding of the transformer T is equipped with a transistor T7, for example.
A switching element 12 composed of the following is connected, and by controlling the switching element 12 on and off with an oscillator 13, an intermittent rectangular current flows through the primary winding. This oscillator 136 analogy is pulse oscillator 1” ()
Equipped with:

The rectifying and smoothing circuit 14 rectifies and smoothes the voltage generated at the secondary winding of the transformer T, smoothes it, and supplies it to the load.
It is equipped with ゜Dx, Da, an inductance L1, a capacitor C, etc.

The detector 15Fi detects whether or not the switching element 12 is in a short-circuit state, and includes transistors T and -P.
1 diodes D4, Ds, etc.

When the first switching resistor 12 is short-circuited,
This is detected from the terminal voltage state of the switching element 12, and the current flowing through the switching element 12 is suppressed.
The control circuit 10 is controlled so that υ.

Next, the operation of this switching power supply will be explained based on FIG. 4.

Switching transistor 1゛7 couplers [&
A pigeon house that normally operates on and off based on the output of G, voltage between the emitter and collector of transistor 'l'7) 1.
1 has a value above a certain threshold, so the line 11-resistance R
1-Diode Ds-A current flows through the base-emitter line of transistor '1' and P, and transistors i' and -p are turned on. Therefore, line 11- :h
, transistors T and C emitter/base-resistance Ra-
) A current flows through the transistors T,, P~line 'o K. Then, due to the base current of the transistors T and -C, and due to the voltage across them, the transistors 'r and -c are brought into a saturated state lpl.
Thus, the primary winding am current of the transformer T is switched and controlled by the transistor T.

However, if the switching transistor T is short-circuited and destroyed, the voltage between the collector and emitter of that transistor T will drop to a very low value below the threshold, and line 11
-Resistor R1 -Diode D4 -Transistor Ill,
- Current often flows via line 10. At this time, the voltage of the transistor T2 decreases to such an extent that no current can flow between the base and emitter of the diode Ds-) transistor If,p due to short-circuit breakdown at the voltage of the diode D4-transistor T,-. Therefore, if transistor Ill is short-circuited, transistor Tr
-P/d is turned off, so the transistor T, -
The base current flowing through C is cut off and the transistor T,-C becomes non-conducting, so that the current flowing through the short-circuited transistor T is abruptly suppressed to zero. In this way, even if the switching element is destroyed in short mode, input 1. Since the voltage can be controlled so that the voltage is not short-circuited, other switching devices 11 that are supplied from the same voltage source will not be adversely affected. Therefore, when a plurality of switching power supplies are differentially connected and used, so-called parallel redundant operation in which other switch power supplies bear the burden of the shortage of switching power supplies caused by this ◆ error becomes easy.

Here, the short final current f yi due to the transistor of the control circuit
- In addition, it is also possible to control the transistor Tll, (2) so as to limit this short circuit current to a constant value.

In addition, at the station mentioned above, we explained an example of using transistors in the control circuit, but thyristor, triac 1
A +'ET1 relay or the like can be used, and not only a single switching circuit system but also a push-pull, half-bridge, bridge, etc. circuit can be used. And the control circuit should only be on the DC side (
, it can also be inserted into the AC circuit side.

Moreover, it can be used not only for switching elements but also for short-circuit protection of simple current control elements.

(7) Effects of the Invention According to the present invention, when a switching element is short-circuited and destroyed, the current flowing through it can be suppressed by roasting it in the face.
11, so that the influence on the outer door circuit can be avoided. Furthermore, the response speed can be increased compared to overcurrent protection circuit systems using fuses, no-fuse breakers, and current transformers, and secondary damage can be prevented. Furthermore, when switching power supplies are operated in parallel, even if an accident as described above occurs in one of them, there is no adverse effect on the other, making parallel redundant operation easier.

[Brief explanation of drawings]

No. 11\I is a configuration diagram of a conventional switching power source, No. 2
FIG. 3 is an explanatory diagram of an overcurrent protection circuit system, FIG. 3 is an example of a block diagram of a switching power supply equipped with a short circuit protection system according to an embodiment of the present invention, and FIG. 4 is a specific circuit diagram thereof.・ In the diagram, ■ is the father's flute source, 2 is the no-fuse breaker, and 3
Fi rectifier diode, 4 is a capacitor, 5.6 is a diode for backflow prevention%, 7.8 is a capacitor for instantaneous interruption,
CT is a current transformer, D is a diode, R is a resistor, C is a capacitor, 9 is a detection circuit, 10 is a control circuit, IIFi transformer circuit, 12 is a switching element, 13 oscillator, 14 is a rectification smoothing circuit, 15 detection Equipment, 5WR-1, 8WR-2
is a switching power supply, Tr. Tr-C, T, -P are transistors, D1td diode, D2 is a rectifying diode, D3 is a commutating diode, D4, D are diodes, R1, R2, R3 are resistors, L is inductance, -LOD is load shows. Patent applicant Akira Yamatani, patent attorney representing Fujitsu Limited.

Claims (1)

[Claims] (1) In a power supply equipped with a switching element that controls on/off the power supply voltage or a control element that controls the current, and a supply means that supplies the output of this switching element or control element to a load, the power supply is connected in series to the switching element or control element. A connected current control means and a short-circuit state detection means for detecting a short-circuit state of the switching element are provided, and the output of the short-circuit state detection means controls the current control means so that the current flows through the switching element when the switching element is short-circuited. A short circuit protection method characterized by controlling the current.