JPS6156977A - Fault detector - Google Patents

Abstract

PURPOSE:To enable the detection of a fault in a semiconductor element or a non-linear type resistance without malfunctioning in a short time after the stoppage of the operation, by checking the voltage of a bridge circuit with all semiconductor elements turned on in a specified period immediately after the operation of a voltage adjusting circuit is stopped. CONSTITUTION:Immediately after the opration of a voltage adjusting circuit 1 is stopped, a pulse is sent from a one-shot multivibrator circuit 15 triggered at the down edge for a specified period to turn ON all of semiconductor elements 21- 24. At this point, charges of snubber capacitors 41-44 are discharged through snubber resistances 31-34 to reduce the shared voltages thereof to zero equally. So, when the elements 21-24 are turned OFF simultaneously, a bridge circuit keeps the balance thereof if the semiconductor elements 21-24 and non-linear resistances 51-54 are all sound, making the output of a voltage detection circuit 7 zero. Any abnormality in the elements 21-24 or resistances 51-54 will break the balance of the bridge circuit. Thus, the circuit 7 can detect a fault.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to failure and detection of a semiconductor element or a nonlinear resistor in a voltage regulating circuit configured in series with a plurality of circuits in which a semiconductor element and a nonlinear resistor are connected in parallel. Regarding equipment.

[Technical background of the invention and its problems].

□ Multiple circuits in which semiconductor elements and nonlinear resistors are connected in parallel17 are configured in series, and the voltage drop in the circuit can be used to adjust the voltage by controlling the semiconductor elements on and off. FIG. 3 is a block diagram of such a voltage regulating circuit, and FIG. 41 is a timing chart.

In the figure, 1 is a voltage adjustment circuit, 21 to 24 are semiconductor elements, 31 to 34 are snubber resistors, 4-1 to 44 are snubber capacitors, 51 to 54 are trivial linear resistors, '61.62 are voltage dividing resistors, 7 8 is a voltage detection circuit, 8 is a DC power supply, 9 is a load resistor, 10 is a semiconductor control circuit, 11 is a time delay circuit, '12.11 inverter τ, and 13 is an AND circuit.

a is an operating signal, b is a failure detection signal, and a' is an output of the delay circuit 11.

Assuming that the semiconductor elements 21-24 are off in FIG. 3, the current from the DC power supply 8 flows into the load resistor 9 via the non-conducting resistors 31-34. At this time, the current flowing into the load resistor 9!・L is the % pressure of the DC power supply 8. E1 non-glandular resistor 51 ~
The limiting voltage of 54 is named ■, and the resistance value of load resistor 9 is RL.
Then, TL = (E 4 v)/RL
0Here, when semiconductor element 2 is turned on, the load current becomes ■
L = (Ei - 3v) / Ry. In this way, the load current IL can be controlled by sequentially turning on the semiconductor elements 17 in order to increase the load current IL, and by turning off the semiconductor elements that are on when decreasing the load current IL. The semiconductor control circuit 10 performs this control.

7) Semiconductor elements 21 to 24 or nonlinear resistor 5
1 = 54 faults, voltage dividing resistors 61 and 62 connected in series are connected in parallel to the voltage adjustment circuit to form a bridge, and the voltage, FF′m *rm
wr x, “5+ E @Wrf)G k f) m
r'dl! The output voltage of the ``5'' ridge circuit is obtained, this voltage is detected by the voltage detection circuit 7, and the semiconductor elements 21 to 24 are detected.
is detecting a failure.

That is, the nonlinear resistors 51 to 54 have approximately the same value, the voltage dividing resistors 61 and 62 have approximately the same value, the snubber resistors 31 to 34 also have the same value, and the snubber capacitor 941 has the same value.
~44 are the same value, so if the semiconductor element and the nonlinear resistance are normal, the output pressure of the bridge circuit is almost zero, but if the semiconductor element 21 or the Pi Jli powder resistor 51 is faulty. When I7 becomes short-circuited, the balance of the bridge circuit is lost, which can be detected by the voltage detection circuit 7. In addition,
Naturally, failure detection is performed by semi-2# body elements 21 to 24.
This must be done when the is in the off state.

However, as shown in Fig. 4, even if this voltage adjustment circuit is operated for a period from T to T and all semiconductor elements are turned off at time T and the operation is stopped, even if Due to the immediate voltage adjustment of T, not all semiconductor elements are necessarily in the on or off state,
The voltage sharing of each semiconductor element is different. Therefore, all the semiconductor elements 21 to 24 or the nonlinear resistor 51
Even if F-54 is normal, immediately after the operation stop time T, the balance of the bridge circuit will be lost due to the difference in the amount of charge that is often observed in Snubber Ronden F-41 to F-44, and the output voltage of the bridge circuit will decrease. □There is a possibility that the pressure will not become zero and it will be determined that there is a failure. When discharging the charges of the snubber capacitors 41 to 44, the impedance of the capacitors connected in parallel with the snubber circuit is large, and the discharge time constant becomes large. There was a drawback that the delay time of the delay circuit 11 had to be several minutes or more.

[Purpose of the invention]

Therefore, an object of the present invention is to solve the above-mentioned points, and to provide a semiconductor device that does not malfunction within a short period of time after the operation is stopped, regardless of the state of the semiconductor device during operation. The object of the present invention is to provide a failure detection device that can detect failures in elements or nonlinear resistors. □ ゛ [Summary of the Invention] In order to achieve this object, the present invention turns on all the semiconductor elements of the voltage regulation circuit for a predetermined period immediately during the rest period after the voltage regulation circuit stops operating, and stores it in the snubber capacitor. This is characterized in that the observed charge amounts are equalized within a short time, so that failures in semiconductor elements or nonlinear resistors can be determined without malfunction within a short time after the operation is stopped.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIG. Components in FIG. 1 having the same functions as those in FIG. 3 are designated by the same numbers, and descriptions thereof will be omitted.

In FIG. 1, 15 is a one-shot circuit triggered by a down edge, and 14 and 16 are OR circuits.

FIG. 2 is a timing chart showing the operation of the present invention.

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 and 2.

Now, the voltage adjustment circuit J of FIG. 1 is turned to T as shown in FIG. 2 by the operation signal a. Assume that the time and operation are from to T. Since the voltage is adjusted during the period up to TO''TI, it is not known which semiconductor elements 21 to 24 are ON and which are OFF, and the operation stop time T
Immediately after , it is considered that the shared voltages of each semiconductor element are different. Therefore, the one-shot circuit 15 which is triggered by the down edge for a predetermined period from time T2 to time T, immediately after time T, outputs a pulse 1 to turn on all the semiconductor elements 21 to 24 of the voltage adjustment circuit 1.

When the semiconductor elements 21 to 24 are turned on at time T2, the snubber capacitor 4 is turned on via the snubber resistors 31 to 34.
The charges 1 to 44 are discharged and the shared voltages of the snubber capacitors 41 to 44 equally become zero in 100 μs@degree. Therefore, at time T3, if the semiconductor elements 21 to 24 are turned off all at once, the semiconductor elements 21 to 24 and the nonlinear resistance 5 are turned off.
If all 1 to 54 are healthy, the bridge circuit is balanced and the voltage detection circuit 7 has zero output. If there is an abnormality in the semiconductor elements 21 to 24 or the nonlinear resistors 51 to 54, the bridge circuit will be in balance. If the balance is lost, the voltage detection circuit 7 can detect the failure. Therefore, if the output of the voltage detection circuit 7 is taken in after time T3, a failure detection signal bl without error can be obtained. The period from T2 to T may be set to a ladder that allows sufficient time for the snubber capacitor to discharge from the time constant of the snubber resistor and the snubber capacitor.

In FIG.
The periods rI and T2 may be set to zero.

In addition, by installing a switch between the voltage adjustment circuit and the load resistor, the circuit current can be bypassed only during periods T and -T3 when all the semiconductor elements 21 to 24 are turned on, or a high resistance can be installed between the voltage adjustment circuit and the load. By providing this in between, it is possible to avoid flowing a large current to the load during one bar stop period.

〔Effect of the invention〕

In contrast to the above explanation, according to the present invention, by detecting the voltage of the bridge circuit after turning on all the semiconductor elements for a predetermined period immediately after the voltage regulating circuit is stopped, malfunction occurs within a short time after the operation is stopped. It is possible to detect failures in semiconductor devices that do not have high resistance or nonlinear resistance.

[Brief explanation of the drawing]

, Fig. 1 is a block diagram showing one embodiment of the failure detection circuit of the voltage regulating circuit according to the present invention, Fig. 2 is its timing chart, and Fig. 3 is a diagram showing a conventional voltage control circuit in which a semiconductor element and a nonlinear resistor are connected in parallel. FIG. 4 is a block diagram showing one embodiment of the failure detection circuit of the adjustment circuit, and is a time chart for explaining the operation of the M3 diagram. 1... Voltage adjustment circuit, 21-24... Semiconductor element,
31-34...Snubber resistor, 41-441° snubber capacitor, 51-54...Nonlinear resistor, 61-62
...Voltage dividing resistor, 7...Voltage detection circuit, 8...DC power supply, 9...Load resistor, 10...Semiconductor control circuit, 11°...Time delay circuit, 12...Inverter , No4...OR circuit, J5...one shot circuit, 16...OR circuit.

Claims (1)

[Claims] A bridge circuit consists of a voltage adjustment circuit configured in series with a plurality of circuits in which a semiconductor element, a snubber circuit, and a nonlinear resistance element are connected in parallel, and a series circuit consisting of a pair of voltage dividing resistors connected in parallel to the voltage adjustment circuit. In the failure detection device, the output voltage of the bridge circuit is obtained from an intermediate point between the voltage adjustment circuit and the series circuit, and a failure of the semiconductor element or the nonlinear resistor is detected. A failure detection device comprising means for bringing all semiconductor elements of the voltage regulating circuit into conduction for a predetermined period after stopping or at the end of an operating period.