JPH0576128A - Circuit protector - Google Patents

Abstract

PURPOSE:To realize highly reliable overcurrent detection wherein an abnormality on the load side does not cause erroneous function even when a relatively large power supply is provided on account of system extension by interposing a power supply signal throw-in/interrupt circuit between a power supply and a load side electronic circuit. CONSTITUTION:When an abnormality occurs in a load side electric circuit and an overcurrent monitor value is exceeded, an overcurrent decision circuit 305 delivers an overcurrent decision signal to an interrupting conditions decision circuit 304 and an operational error occurs due to the abnormality in the load side electronic circuit. Consequently, an error signal is also delivered on a load error derive line 318 to the interrupting conditions decision circuit 304. which thereby delivers a current interruption command signal on an interruption command notifying line 319. Consequently, an OFF command signal for a power transistor 310 is delivered to a transistor control circuit 303 such that the load side circuit is protected against damage due to overcurrent and current machines for the load side electronic circuit are interrupted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention cuts off the supply of an electric current to an electronic circuit formed on a printed board of an electronic device when the electric current is excessively large, thereby causing a fatal damage to the electronic circuit. The present invention relates to a circuit protection device that prevents

[0002]

2. Description of the Related Art For example, an electronic circuit is formed on a printed circuit board which constitutes a large number of modules inside an electronic computer. The electronic circuit is formed between a power supply section and a load side electronic circuit in this electronic computer. Monitor the fluctuation of the flowing current value,
There is provided a circuit protection device that prevents the electronic circuit from being fatally damaged or causing a fire by cutting off the supply of an excessive current.

That is, due to an abnormality in a component forming an electronic circuit on the load side with respect to the power source, an excessive current may flow into the circuit to generate heat, leading to smoking or ignition. In order to prevent this, conventionally, the following circuit protection means has been used.

The first circuit protection means is provided with an overcurrent detection circuit on the power supply side, and when the overcurrent detection circuit detects that a current exceeding a certain value is flowing, the power supply itself outputs its output. Cut off. The second circuit protection means is provided with a breaker for the output of the power supply, and cuts off the current supply to the load side by detecting an overcurrent at the breaker. The third circuit protection means is
A breaker is provided at the load side input section, and the current supply is cut off by detecting overcurrent at this breaker.

In general, in electronic equipment, especially in a typical electronic computer, even if they are of the same model, the number of modules and printed boards differ depending on the system scale, and the user initially has a small system configuration. It is often introduced and the scale is expanded in accordance with the expansion of business. For this reason,
It is desirable that the power supply of the electronic computer can withstand future system expansion, and normally the power supply capacity (rated current) is based on the load current with the maximum number of modules.
Is set.

Here, in the above-mentioned first circuit protection means, that is, the circuit for protecting the circuit by detecting the overcurrent flowing to the load side by detecting the overcurrent of the current, the current flowing when the load side becomes abnormal becomes the power source. It is necessary to exceed the overcurrent detection value, and this overcurrent detection point is usually 1
It is often set to about 10 to 120%.

However, as described above, for a power supply having a large capacity assuming the maximum system scale,
In the case of an electronic computer with a small-scale system configuration connected to the load side, even if an abnormality occurs in the load side circuit and a current that greatly exceeds the steady current of the load flows, the overcurrent detection value of the power supply is In some cases, the current may not be exceeded, and current supply may not be cut off, resulting in circuit damage.

Therefore, a power supply for the electronic computer is provided independently for each very small circuit block, and an overcurrent detection point that slightly exceeds the rated current for each block is set for each power supply. It may be possible to install an overcurrent detection circuit, but the system configuration becomes complicated and addition is complicated, and the risk of power shutdown due to malfunction increases in proportion to the number of installations, and reliability is impaired. There is.

It is possible to change and set the overcurrent detection point of the power supply side overcurrent detection circuit according to the actual load current corresponding to the actual system scale. It is necessary to change the overcurrent detection point, and even if the power supply unit of the same type cannot be used for other computer systems as it is, compatibility cannot be maintained. It is necessary to reset the current detection point, which is very troublesome to handle and is prone to human error.

On the other hand, the second and third circuit protection means, that is, the circuit protection means provided with a breaker on the power source side or the load side, is essentially the same as the above-mentioned means for protecting by the overcurrent detection of the power source. However, if you try to make the overcurrent detection point of the breaker correspond to the steady current on the load side, it is necessary to install a breaker independently for each small block in the system, which complicates the system configuration. In addition, there is a problem that reliability is deteriorated due to an increased risk of malfunction.

[0011]

That is, from the viewpoint of protecting an electronic circuit, a circuit that detects an overcurrent and cuts off the current supply is installed everywhere in the system, that is, in each small block. Although fine-grained protection is possible, increasing the number of installations increases the risk of malfunctions, that is, the risk of interrupting the supply current regardless of whether or not the circuit is operating. To achieve this, the reliability of overcurrent detection in the overcurrent detection / cutoff circuit itself must be ensured.

The present invention has been made in view of the above problems,
To provide a circuit protection device that enables reliable overcurrent detection without fear of malfunction due to an abnormality that occurs on the load side even when a large power supply is provided in consideration of system configuration expansion. To aim.

[0013]

That is, a circuit protection device according to the present invention is provided with a closing / cutting circuit which is provided between a power supply and a load side electronic circuit to turn on / off a power signal. Current detection means for detecting the current value of the power supply signal supplied to the load side circuit, and a preset overcurrent monitoring value for which the load side supply current value detected by this current detection means is higher than its steady current value. Overcurrent determination means for determining that it has exceeded, load error derivation means for deriving an error signal accompanying the operation error of the load side circuit, and overcurrent determination of the overcurrent determination value by the overcurrent determination means The load error deriving means includes a cutoff condition determining means for issuing a power signal cutoff command to the closing / cutting circuit when the error signal is derived.

[0014]

In other words, the current interruption condition is not satisfied unless the condition elements of the two systems, that is, the overcurrent judgment value excess judgment by the overcurrent judgment means and the error signal derivation state by the load error derivation means are all aligned. Since the power supply signal to the load side circuit is not shut off, reliable and highly reliable circuit protection by overcurrent detection / shutdown can be performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a computer system equipped with a circuit protection device, and this computer system is driven by a power supply 10.

The power supply signal output from the power supply 10 is distributed and supplied to a plurality of circuit blocks consisting of the printed boards 41 to 46 through the power supply bus bar 20. The circuit blocks 41, 42, 42, 43, 44-
For each 46, independent overcurrent detection / cutoff circuits 31 to 33 are provided for the respective power input terminals.

The overcurrent detection / cutoff circuits 31 to 33 are
A switching function for turning on / off a power supply signal from the power supply busbar 20 to the corresponding circuit blocks (loads) 41, 42, 43, 44 to 46, an overcurrent detection function for detecting an overcurrent state of a supply current value, and each With an error derivation function for deriving an error signal from the corresponding circuit block, the current cutoff condition based on the overcurrent determination signal obtained by the overcurrent detection function and the error signal obtained by the error derivation function When the determination is made, the supply of the power signal to the load side is cut off by the switching function.

Here, each of the above-mentioned overcurrent detection / cutoff circuits 3
For 1, 32 and 33, error signals associated with operation errors of the circuit blocks 41, 42, 43 and 44 to 46 are derived via the corresponding load error derivation lines 41a, 42a and 44a.

FIG. 2 shows the internal configuration of the overcurrent detection / cutoff circuits 31 to 33 in the computer system. DC supplied from the power supply line 311 on the power supply busbar 20 side.
The power signal is a power transistor 301 and a resistor 302.
Is output to the power line 312 on the load side via.

The power transistor 301 turns on / off a current to / from the load side, and this power transistor is controlled by a power supply system controller (not shown) via a signal line 320 in accordance with operation of a main power switch or the like. ON / OFF control is performed based on an ON / OFF command signal given to the circuit 303, and OFF given to the transistor control circuit 303 from a cutoff condition determination circuit 304 described later via a cutoff command notification line 319.
OFF control is performed based on the command signal.

The resistor 302 captures the supply current to the load side as a voltage through the voltage detection lines 313 and 314. The supply voltage captured through the voltage detection lines 313 and 314 passes through the A / D converter 306. It is converted into a digital value at regular intervals, and is updated and held in the register 307 via the data line 315. The digital voltage data corresponding to the load-side supply current held in the register 307 is supplied to the overcurrent determination circuit 305 via the data line 316.

This overcurrent judging circuit 305 judges on the basis of the digital voltage data given from the register 307 that the load side supply current has exceeded a predetermined overcurrent monitoring value and outputs an overcurrent judging signal. Therefore, the overcurrent determination signal output from the overcurrent determination circuit 305 is given to the cutoff condition determination circuit 304 via the overcurrent determination line 317.

Here, the overcurrent monitoring value of the load side supply current is set to an overcurrent value (for example, a steady current +3 A) at which a large damage does not occur immediately in the load side circuit. The monitor value is arbitrarily set by a digital variable switch provided in the overcurrent determination circuit 305. An error signal associated with the error operation of the load side circuit is given to the cutoff condition determination circuit 304 via the load error derivation line 318.

The cutoff condition judging circuit 304 is based on the overcurrent judging result by the overcurrent judging circuit 305 and the error signal deriving result from the load error deriving line 318.
The condition is determined whether to interrupt the current supply to the load or to give a malfunction notification of overcurrent detection. The current interrupt command (OFF) signal based on the interrupt condition determination from the interrupt condition determination circuit 304 is interrupted. Command notification line 31
The transistor control circuit 303 is given via 9 and the malfunction command signal based on the malfunction condition judgment from the shut-off condition judging circuit 304 is supplied to the power supply system control unit (not shown) via the signal line 321. Next, the operation of the computer system including the circuit protection device having the above configuration will be described.

First, to operate the computer system,
When a main power supply switch (not shown) is operated, the power supply 10 is turned on by a power supply system control unit (not shown), and the overcurrent detection / cutoff circuits 31 to 33 are sequentially connected to the transistor control circuit 303 via a signal line 320. A power-on command signal is supplied, whereby the power transistor 301 is held in the ON state, and the power signal provided from the power-source power line 311 is the power transistor 301, the resistor 302, and the load-side power line. Each corresponding circuit block 41, 42, 4 via 312
3, 44-46.

The load side circuit blocks 41, 42, 4
3, the voltage detection lines 313 and 314 derived from both ends of the resistor 302 in each of the overcurrent detection / cutoff circuits 31 to 33 are supplied with a voltage proportional to the supply current to the load side circuit. This voltage signal is obtained, and is converted to a digital value by the A / D converter 306 at regular intervals, updated and held in the register 307, and simultaneously given to the overcurrent determination circuit 305.

Here, for example, when an abnormality occurs in the load side electronic circuit and the current value supplied through the transistor 301 and the resistor 302 exceeds the steady current +3 A, that is, the overcurrent monitoring value, the overcurrent determination circuit. An overcurrent determination signal is supplied from 305 to the cutoff condition determination circuit 304, and an operation error associated with an abnormality occurs in the load side electronic circuit, so that the error signal also passes through the load error derivation line 318. Given to 304.

Then, the breaking condition judging circuit 304 judges whether or not the current supply breaking condition for the load side is satisfied, and outputs the current breaking command (OFF) signal to the breaking command notification line 319. In order to prevent damage to the load side circuit due to current, an OFF command signal for the power transistor 301 is given to the transistor control circuit 303, and the current supply to the load side electronic circuit is cut off.

Here, the reason for using the judgment result of the overcurrent state with respect to the load side electronic circuit and the derivation result of the error signal in the load side electronic circuit as the condition judging elements for judging the above current interruption condition That is, when an overcurrent flows due to, for example, a short circuit in the electronic circuit, the function of the electronic circuit cannot be normal, and at the same time when the overcurrent occurs, some operation error is detected in the circuit. By using such two-system information associated with overcurrent as a condition determination element, for example, the A / D converter 306, the register 307, or the overcurrent determination circuit 305 is used. Even if an erroneous overcurrent condition occurs due to a failure, the current to the load side electronic circuit will not be interrupted, and the reliability of circuit disconnection due to overcurrent detection will be improved. To the real thing.

On the other hand, if the error signal from the load error derivation line 318 is not derived even if the overcurrent determination signal from the overcurrent determination circuit 305 is given to the cutoff condition determination circuit 304, the A / D converter 306. Or register 307,
Alternatively, it is determined that the malfunction occurs due to a failure of the overcurrent determination circuit 305, and the cutoff condition determination circuit 304 outputs the signal line 321.
On the other hand, an "error" signal is output as a malfunction command signal.

As a result, in the power supply system control unit (not shown), the fact that a failure has occurred in the overcurrent detection / interruption circuit to which the above-mentioned "error" signal is applied is managed by the system notifying means such as display and voice not shown. Personnel and maintenance personnel will be notified.

Therefore, according to the circuit protection device having the above configuration, the voltage proportional to the current supplied to the load side circuit, which is obtained by the resistor 302 interposed in the load side power supply line 312, is passed through the A / D converter 306. Converted to digital data and held in the register 307, the overcurrent determination circuit 30
5 determines that the load-side supply current has exceeded the overcurrent monitoring value higher than the steady-state current, and only when the operation error signal of the load-side circuit is derived by the load error derivation line 318, the cutoff condition determination circuit. Since it is determined in 304 that the current cutoff condition is satisfied and the OFF command signal for the power transistor 301 is given to the transistor control circuit 303 to cut off the current supply from the power supply line 311 on the power supply side, there is no risk of malfunction. The circuit can be cut off by overcurrent detection, and even if this overcurrent detection / cutoff circuit is installed individually for each divided module, reliable reliability is obtained and fine circuit protection is possible. ..

As a result, even if a large power supply is provided in advance in consideration of the expansion of the system configuration, circuit protection by reliable overcurrent detection and current interruption can be performed from a small system configuration to a large system configuration. It will be possible.

In the above embodiment, the overcurrent detection / cutoff circuits 31 to 33 are installed for arbitrarily divided modules or printed boards, and the respective currents can be cut off by independent overcurrent detection. When an individual module or printed board fails, it is possible to easily replace only the failed module or printed board online.

[0035]

As described above, according to the present invention, the load side circuit is provided with the make / break circuit provided between the power source and the load side electronic circuit for making and breaking the power signal. Current detection means for detecting the current value of the supplied power supply signal, and determining that the load side supply current value detected by this current detection means has exceeded a preset overcurrent monitoring value higher than its steady current value Overcurrent determining means, a load error deriving means for deriving an error signal associated with an operation error of the load side circuit, and an overcurrent monitoring value excess determination by the overcurrent determining means and the load error deriving means. Since an error signal is derived from the power supply circuit, it is configured to include a cutoff condition determination means that issues a power supply signal cutoff command to the closing / turning off circuit. Even when myself understood, without fear malfunction to abnormality occurring in the load side, allowing reliable overcurrent detection.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a computer system including a circuit protection device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an internal configuration of an overcurrent detection / interruption circuit in a computer system including the circuit protection device.

[Explanation of symbols]

10 ... Power source, 20 ... Power source bus bar, 31-33 ... Overcurrent detection / interruption circuit, 41-46 ... Printed board (circuit block), 41a, 42a, 44a ... Load error derivation line, 301 ... Power transistor, 302 ... Resistor , 30
3 ... Transistor control circuit, 304 ... Breaking condition judging circuit, 305 ... Overcurrent judging circuit, 306 ... A / D converter,
307 ... Register, 311, 312 ... Power supply line, 31
3, 314 ... Voltage detection line, 315, 316 ... Data line, 317 ... Overcurrent determination line, 318 ... Load error derivation line, 319 ... Shutdown command notification line, 320,
321 ... Signal line.

Claims (1)

[Claims] 1. A circuit protection device provided between a power supply and a load side electronic circuit, the circuit protection device having a make / break circuit for making / breaking a power signal, wherein a current value of a power signal supplied to the load circuit. A current detection means for detecting the above, an overcurrent determination means for determining that the load-side supply current value detected by the current detection means exceeds a preset overcurrent monitoring value higher than its steady-state current value, and The load error deriving means for deriving an error signal associated with the operation error of the load side circuit and the overcurrent judging means for judging the excess of the overcurrent monitoring value, and the load error deriving means for deriving the error signal. At this time, a circuit protection device comprising: a cutoff condition determination means for issuing a command to cut off the power supply signal to the closing / cutting circuit.