JPH02290126A - Semiconductor breaker device - Google Patents

Abstract

PURPOSE:To limit a main circuit current with a high degree of accuracy by providing a main circuit current measuring means, a current limiting time calculation circuit, a semiconductor element driving micro current generating circuit, a semiconductor element generating circuit in the event of rating, and a controlling circuit to cut-off a semiconductor element driving circuit and a micro current generating circuit when the main circuit has overcurrent. CONSTITUTION:When a main circuit current has a higher value than that of an overcurrent setter 20, the output of a NOT gate element 38 is cut-off, and the output of an AND circuit 39 is also cut-off. The output voltage of a current sensor 9 and the voltage of a current limiting value setter 31 are compared with a differential amplifier circuit 19, and IB2 is so controlled that a current to be supplied to a transistor Q1 is equal to a current limiting value. In the event of exceeding a current limiting time, an OFF signal is outputted to an AND circuit 37, IB2 of the transistor Q1 is also st to 0, the transistor Q1 is turned OFF, and a main circuit is opened. According to the constitution, the main circuit current can be limited with a high degree of accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor interrupting device for opening and closing an electric circuit.

[Prior art] FIG. 3 shows, for example, -TIIREE TYPES OF
SQLID STATE REMOTE POWER
CONTROLLERS-, D. E. Ilake
r I'ESC75 RECORD PI51~P1
60 is a circuit of a conventional semiconductor cut-off device described in No. 60.

When there is a command to turn on the semiconductor cutoff device in this circuit, an on signal is input from the ON/OPF control circuit 6 to the transistor Qa. First, transistor Q[l
turns on and IRI flows through resistor R1.
RI is transistor Q4. Qs. It is increased by Q2 and causes III to flow through transistor Q+ as a base current. In other words, the base drive circuit 12 is turned on. Therefore, the transistor Ql turns on, and the main circuit from the DC power supply 1, which is the main circuit power supply, to the current sensor 9 using a current-to-voltage converter, the transistor Q1, the diode l4 for reverse voltage prevention, and the load 2 such as a motor. The circuit will be shut down. Further, when an off signal is input to transistor QII from the ON/OFF control circuit 6, transistor QO is turned off, and therefore transistor Q4. Qs.
Q2 and Q1 will be turned off and the main circuit will be opened.

If an accident such as a load short circuit occurs in this main circuit, the overcurrent setter 20, voltage comparator 30, not gate element 38, etc. in the ON/OFF control circuit will be activated. That is, it is detected from the signal from the current sensor 9 that an overcurrent has flowed through the main circuit, and the base drive circuit 12 is turned off, the transistor Q1 is turned off, and the main circuit is cut off.

[Problems to be Solved by the Invention] Generally, when a large current flows through a circuit breaker due to a circuit failure such as a short circuit, a current of 10 times the rated value or more on the order of μsec is generated in the moment before the circuit starts breaking operation. There is a possibility that a current flows and then a blocking operation occurs. At this time, when this instantaneous large current flows to a circuit breaker higher than that circuit breaker, there is a problem that the upper circuit breaker reacts to the large current and performs an unnecessary breaking operation. If the upper circuit breaker 80 performs a breaking operation due to a failure such as a load short circuit, a problem will occur in that normal circuits equipped with other circuit breakers such as 82, 83, etc. will also be cut off.

As mentioned above, it is necessary for the circuit breaker used as a lower-level circuit breaker to prevent the upper-level circuit breaker from operating during the time period from when a current exceeding the rated value flows until the circuit breaker initiates a breaking operation. For this purpose, a method can be considered in which the current value exceeding the rated value that flows during the above-mentioned time is limited to, for example, 2 to 3 times the rated current, that is, the current is limited.

However, in the case of a failure such as a load short circuit as described above, the collector-emitter voltage of the transistor Q1 becomes extremely high. Therefore, the operating region of transistor Ql is the fifth
Moving from point A to point C on the dotted line indicating the normal operating range shown in the figure, a current exceeding the current limit flows through the transistor Ql. In order to prevent this state from occurring, the base current 11 is set such that the operating region of transistor Q1 is indicated by a solid line.
It is necessary to change the operating range to a lower one. That is, in order to perform current limiting as described above in the event of a circuit failure such as a load short circuit, the base current I. It is necessary to control B to a low level. become. For example, if the actual operating point changes from point A to point B at this time, the collector current of transistor Q1 will be 2 to 3 times higher than the rated current.
It will be suppressed twice. In other words, the flow of III, which was, for example, 10^ at the rated time, will be reduced to about 1/3 at the time of failure.
Lowering the current to 100mA means that the collector current can be kept within a safe range. However, in reality, this Ill is controlled by IRI as explained above. The relationship between this 1.1 and IRI is simply that each transistor Qs. Qs. It is determined according to the current increase [1] rate with Q2. For example, transistor Q4 is 1
00 times, Q3 has a current increase factor of 50 times, and Q2 has a current increase factor of IO times 11, then the overall amplification factor from Q4 to 02 is IOO
X 50X lO=sOOOOo times. In other words, the IRI which is normally about (IOA (l 1 1) / 50000 times} = 0.2 mA) will be reduced to about (100 - ^ (let) / soooo times} = 2 μA when a failure occurs. 2μ^ to 0.2w
It has been extremely difficult to control 1t1 over a wide range up to about +A and supply a stable base current.

Therefore, as mentioned above, the base current 18l is
■ Stable control in the range from A to IOA has been a challenge for semiconductor cut-off devices.

This invention was made in order to solve the above-mentioned problems, and provides a semiconductor interrupting device that can accurately limit the main circuit current by supplying a stable base current from the time of a failure such as a short circuit to the rated state. The purpose is to

[Means for Solving the Problems] A semiconductor interrupting device according to the present invention includes a main circuit current measuring means, and a main circuit current measuring means that causes the main circuit current to flow through the main circuit according to the main circuit current value measured by the main circuit current measuring means. a current-limiting time calculation circuit that calculates the current-limiting time (referred to as current-limiting time); a microcurrent generating circuit for driving a semiconductor element that controls the current-limiting of the main circuit current based on a signal from the main circuit current measuring means; When a current (overcurrent) exceeding the rating flows in the main circuit of the semiconductor element drive circuit at the rated time, the semiconductor element drive circuit at the rated time is turned off, and the overcurrent exceeds the current limit time. a control circuit that continuously turns off the microcurrent generating circuit for driving a semiconductor element when two currents are flowing.

[Function] In the semiconductor interrupting device of the present invention, when an overcurrent flows in the main circuit, the circuit for driving the semiconductor element at the rated state is turned off,
During the current-limiting time, the semiconductor element drive minute current generating circuit that performs current-limiting control limits the overcurrent in the main circuit and allows it to flow.

[Example] A semiconductor cut-off device according to the present invention will be described with reference to FIGS. 1 and 2 showing one implementation thereof. FIG. 1 is a circuit diagram of a semiconductor interrupting device, and FIG. 2 is a diagram showing changes over time of main currents in the circuit of FIG. 1.

First, a description will be given of when a constant 4 J current flows through the semiconductor cut-off device during a jump.

In order to close this semiconductor cut-off device from the outside, first turn it on.
An ON command is input to the /OFF control circuit 6°.

At this time, a current sensor 9 using a known current-to-voltage converter
The signal from is 0^, which is naturally smaller than the current value set by the overcurrent setting device 20. As a result, the voltage comparator 30 outputs an off signal, and the output of the not gate element 38 is turned on. Therefore, the output of the AND circuit 39 is turned on,
Base drive circuit at rated time! Turn on 2. That is, transistor QD is turned on, and base current Ill becomes Q4.
For example, IOA flows due to the effect of transistors Q3 and Q2, and transistor Q1 is turned on. Therefore, the main circuit connected from the DC power supply 1, which is the main circuit power supply, to the load 2 via the current sensor 9, the transistor Q+, and the reverse voltage prevention diode 14 is shut off. Also, at the same time, the 0^ signal from the current sensor 9 is input to the current limit time calculation circuit 35, which is comprised of a known hyperbolic function generation circuit or the like. The current limit time calculation circuit 35 sets the current limit time to infinity (ω) when the signal from the current sensor 9 is below the rated current. That is, a pulse number signal m corresponding to an infinite time is inputted to the input terminal of the comparator (digital comparator) 36 in order to allow the main circuit current below the rated current to flow without any time limit.

Further, since the voltage comparator 30 is in the OFF output as described above, the pulse number signal n is not outputted from the AND circuit 33 and the counter circuit 34 described below, that is, it is O. Therefore (
When the input to the input terminal is greater than the input to the input terminal, the output of the comparator (digital conhalator) 36, which turns on the output, is turned on. This ON signal and an external ON command pass through the AND circuit 37 and turn on the switching circuit 23 which turns on the base drive circuit 4l during current limiting.

At this time, the current limiting base drive circuit 4l operates as follows. That is, since the output voltage from the current sensor 9 with respect to the OA or rated main circuit current is smaller than the voltage of the current limit value setter 3l, the differential amplifier 19 outputs a positive voltage. This output is input to the adding circuit 2l through the integrating circuit 25 with a limiter circuit. The limiter circuit added to this integrating circuit has the function of not outputting more than a certain voltage to the adding circuit 2l even if the output voltage of the differential amplifier l9 is integrated and becomes larger. For example, this limit value is set to ±50 mA in terms of base current IB. Here, the voltage of the Is2 setter 22 is the base current]
When converted to 9 and set to 100mA, in this case, adder circuit 2! The output voltage is lOQsA+ 50mA=
The voltage is equivalent to 150mA. This voltage is the switching circuit 2
3, the constant current circuit 24 performs voltage/current conversion, and supplies 1112 (in this case, !50 mA) to the transistor Q1. Therefore, in the end, the base current 1B of the transistor Qr becomes II+-1-IB2 (for example, 10.15 A). In this state, the transistor Ql is turned on and the circuit breaker is idle.

Next, a case will be described in which the main circuit current suddenly increases due to a load short circuit or the like and becomes larger than the preset value of the overcurrent setting device 2o. At this time, the voltage comparator 30 in the ON/OFF control circuit 6 will output an ON signal. Therefore, the output of the 7t gate element 38 is turned off, and the output of the AND circuit 39 is also turned off. Therefore, the base drive circuit 12 is turned off at the rated time. That is, r
B1=o.

However, at this time, the current-limiting time calculation circuit 35 calculates the current-limiting time, for example, romsec, according to its built-in hyperbolic function for the main circuit current that has suddenly increased.

That is, the pulse number signal m for this lO■Sec is applied to the ten input terminal of the comparator 36. On the other hand, the voltage comparator 3 mentioned above
The ON output of 0 is input to the AND concave path 33, so that a clock pulse from the oscillator 32 appears at the output of the AND circuit 33. This clock pulse is sent to the counter circuit 34.
The number of pulses is counted. Therefore, this pulse number signal n is applied to the single output terminal of the comparator 36. In other words, this comparator 36
The actual overcurrent state time input to the single power terminal is compared with the current limit time calculated in 0■see, and ma
During n, an ON signal is output to the AND circuit 37. In other words, even if an overcurrent occurs, the switching circuit 23 of the base drive circuit during current limiting is kept on during the current limiting time.

Therefore, the above result base current ■8 is lH+Im2(
For example, 10. 15A) to IB2 (e.g. 150mA)
).

This suppresses the current 1c flowing through the transistor Q1, but the differential amplifier circuit 19 compares the output voltage of the current sensor 9 that detects this current IC with the voltage of the current limit value setter 31. When (output voltage of 9) > (set voltage of 31), by making the output voltage of 19 negative and inputting it to the integrating circuit with limiter circuit 25, the 1V from 25 is
The value becomes negative, and the output of the addition port 21 also becomes small. As a result, the base current 112 from the constant current circuit 24
becomes small, and the current flowing through transistor Q1 also becomes small. Also, when (output voltage of 9) < (set voltage of 31), ! By making the output voltage of No. 9 positive and inputting it to the integrating circuit with limiter circuit 25, the tuna of Iv No. 25 becomes large, and the output of the adder circuit 2l also becomes large. As a result, the base current 112 from the constant current circuit 24 increases, and the current flowing through the transistor Q1 also increases. By repeating this operation, the base drive circuit 4l at current limit becomes (output voltage of 9) = (set voltage of 31), that is, current flowing through transistor Q1 = current limit value (value about 2 to 3 times the rated current). ).

Also, when the overcurrent state time exceeds the current limit time, the ON/
The state of the input of the comparator 36 in the OFF control circuit 6 is ma
n, and an off signal is output to the AND circuit 37. Therefore, the switching circuit 23 is also turned off. Therefore, +12 for transistor Ql also becomes 0, transistor Q1 is turned off, and the main circuit is opened.

Ru.

In this embodiment, the current-limiting base drive circuit 41 is operated even during normal times. This is to prevent the base current Is of the transistor Qt from instantaneously becoming 0 due to a delay in the rise of the base drive circuit 4l during current limiting when switching from normal to current limiting, and to perform stable current limiting operation. It is something.

In the above embodiments, the main circuit elements such as Qz are transistors, but the same effect can be obtained in a circuit using elements other than transistors, such as silice.

Further, the same effect can be obtained when not only one transistor Q1 but two or more transistors Q1 of the main circuit are combined.

[Effects of the Invention] As described above, according to the present invention, when an overcurrent flows in the main circuit of the semiconductor interrupting device, the rated base drive circuit is turned off. Further, it has a current limiting base drive circuit that allows the overcurrent to flow while controlling it to the current limiting value only during the current limiting time at the time of overcurrent. Therefore, it is possible to obtain a highly reliable semiconductor circuit breaker device that does not have the risk of flowing a current so large as to operate a higher order circuit breaker during current limiting.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of the present invention, Fig. 2 is a diagram showing changes in main currents over time in the circuit of Fig. 1, Fig. 3 is a circuit diagram of a conventional semiconductor cut-off device, and Fig. 4 is a cut-off diagram. FIG. 5 is a VCE-IC characteristic diagram of transistor 01. In the figure, 9 is a current sensor, 12 is a rated base drive circuit, 41 is a current limiting base drive circuit, 35 is a current limiting time calculation circuit, and 6° is an ON/OFF control circuit.

Claims (1)

[Claims] (1) Main circuit current measuring means, current limiting time for calculating the time during which the main circuit current can flow through the main circuit (referred to as current limiting time) according to the main circuit current value measured by the main circuit current measuring means. a calculation circuit, a micro current generation circuit for driving a semiconductor element that controls current limiting of the main circuit current according to the signal of the main circuit current measuring means, a circuit for driving the semiconductor element at a rated time that causes a predetermined current to flow through the main circuit; When a current exceeding the current limit (overcurrent) flows, the circuit for driving the semiconductor element at the rated state is turned off, and when the overcurrent flows for more than the current limit time, the circuit for driving the semiconductor element is continuously turned off. A semiconductor cut-off device comprising a control circuit that turns off.