JPH08308094A - Circuit breaker apparatus - Google Patents

Abstract

PURPOSE: To prevent generation of noise by suppressing a sudden change of current at the time of cutting off the current flowing into a current path of a load. CONSTITUTION: Output current paths of IGBT 10 to 16 are inserted into a current path of a load 20. Upon detection of a current higher than the predetermined current in the current path of the load, detecting means 22 to 26 change an output signal status. Control means 28 to 48 control IGBT to the conductive condition under the normal condition and when the detecting means controls such IGBT to the non-conductive condition after IGBT is saturated when the output signal status is changed. Namely, when IGBT is saturated, a current flowing into this IGBT becomes a constant current. Therefore, when an over- current flows into the load, such current sequentially increases and becomes constant for a certain period and thereafter it is decreased. Thereby, a sudden change can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breaker device for breaking a current path of a load when an excessive current flows through the load.

[0002]

2. Description of the Related Art For example, in a semiconductor measuring device, when conducting a short-circuit test for a high-current semiconductor element such as a power MOSFET or an insulated gate bipolar transistor, the voltage between the collector and the emitter is increased in order to increase the voltage between the collector and the emitter. Test for short circuit. Here, if the semiconductor device under test is short-circuited, an excessive current may flow into the semiconductor measuring device, which may damage the semiconductor measuring device itself. In this case, the semiconductor device under test becomes a load in the current path. Further, when the load is a motor, if a short circuit occurs between both ends of the main current path due to a failure of the motor, an excessive current may flow and the motor control circuit may be destroyed.

As described above, in various electric circuits, when an excessive current flows due to a short circuit of the load or a ground drop (the current path of the load drops to the ground), the load itself is further destroyed, and peripheral circuits and control circuits of the load. Can also be destroyed. Therefore,
If an excessive current flows through the load, a breaker device that instantaneously cuts off the current path of the load is required. Note that the home breaker device uses an electromagnetic relay and is not suitable for high-speed breaking operation.

A rapid breaker or a super rapid fuse is one of conventional breaker devices for instantaneously breaking off an excessive current. However, these special fuses are expensive and are single-use disposables. In particular, when an excessive current flows each time as in a short circuit test of a semiconductor device, it becomes very uneconomical.

Another conventional high-speed breaker device is a breaker device using an insulated gate bipolar transistor (IGBT) proposed by the present applicant. This I
In the GBT breaker device, N IGBTs are arranged in parallel, and the main current path between the collector and the emitter of each IGBT is inserted in the current path of the load. The gate bias voltage from the control circuit is supplied to the gate of each IGBT,
In the normal state, the IGBT is guided to the normal state. Therefore, each IGBT
Since about 1 / N of the current flowing through the load flows through the device, it can withstand a large current as a whole. A small resistor inserted in the current path of the load converts the current flowing in the load into a voltage,
When this voltage exceeds the reference value, an excessive current is used to cause the control circuit to make each IGBT non-conductive. In addition, N IG
If multiple BT combinations are connected in series, the IGBT
The withstand voltage as a whole can be increased. This IGBT breaker device can be used many times and is very economical.

[0006]

FIG. 4 shows the above-mentioned IGB.
It is a figure which shows operation | movement of T breaker apparatus. In this figure, the horizontal axis represents time and the vertical axis represents current flowing through the IGBT breaker device and the load. When the IGBT breaker device is in the conductive state and the power supply voltage is supplied to the load, the normal current Is starts to flow. When the load is short-circuited or grounded at time t0, the current starts to increase with a slope determined by the inductance component and the resistance component of the current path. When the current reaches Isat at the time point t1, the voltage drop of the current detection resistor in the load current path also reaches a predetermined value, and the control circuit makes the IGBT non-conductive, so that the current rapidly decreases. .

In the case of this conventional IGBT breaker device,
As shown in FIG. 4, at the cutoff time t1, the current is rapidly converted from an increase to a decrease, so that spike noise may occur, and the load control circuit and peripheral circuits may malfunction or be destroyed. is there. Also, the load itself may be destroyed if the load is not yet destroyed.

Therefore, an object of the present invention is to provide a breaker device which prevents a sudden change in the current when the current flowing in the current path of the load is cut off.

[0009]

SUMMARY OF THE INVENTION The present invention is a breaker device for shutting off a current path of a load when an excessive current flows through the load, and an output current path of a semiconductor element is inserted in the current path of the load. There is. The detection means changes the output signal state when it detects that a predetermined current or more has flowed in the current path of the load. The control means controls the semiconductor element to be in a conductive state in a normal state, and when the output signal state of the detection means changes, controls the semiconductor element to be in a non-conductive state after the semiconductor element is saturated. That is, when the semiconductor element is saturated, the current flowing through this semiconductor element becomes a constant current. Therefore, when an excessive current flows through the load, the current increases sequentially, becomes a constant value for a certain period, and then decreases.
It is possible to prevent a rapid current change as shown in FIG. Since sudden current changes disappear, spike noise can be prevented.

[0010]

1 is a block diagram of a preferred embodiment of the present invention. In this embodiment, the IGBTs, which are semiconductor elements, are arranged in m rows and n columns (m = 2, n = 2).
The collectors and emitters of 10 and 12 are interconnected, respectively, in parallel. Also, the IGBTs 14 and 16
The collectors and emitters of are also interconnected,
Make them in parallel. The collectors of the IGBTs 10 and 12 are IGB
Two sets of parallel circuits are connected in series by connecting to the emitters of T14 and T16. Therefore, these IGBTs 10-16
Results in twice the maximum current and maximum breakdown voltage as in the case of a single IGBT. The main current path of the semiconductor element is between the collector and the emitter of the IGBT. These IG
The main current path of the BT, the power supply 18, the load 20, and the current detection resistor 22 are connected in series, and a voltage is applied from the power supply 18 to the load 20. The load 20 may be the device under test of the semiconductor measuring device or a motor as described above.
In the case of a semiconductor measuring device, a means for measuring the voltage supplied to the load 20 and a means for measuring the voltage drop of the resistor 22 are provided to measure the voltage-current characteristic of the load 20.

The differential amplifier 24 determines the voltage difference across the resistor 22, that is, the voltage proportional to the current flowing through the load 20. The comparator 26 compares the output voltage of the differential amplifier 24 with the reference voltage Vref, and when the current flowing through the load 20 reaches a predetermined value, changes its output state. Therefore, the resistor 22, the differential amplifier 24, and the comparator 26 serve as detection means that changes the output signal state when detecting that a predetermined current or more has flowed in the current path of the load.

The delay circuit 28 delays the output signal of the comparator 26 and supplies the delayed comparison output signal to the amplifiers 34 and 36 via the optical couplers 30 and 32. The amplifier 34 is
A gate control signal is supplied to the gates of the IGBTs 10 and 12, respectively, through a small resistor, for example, a resistor 38 of 100Ω, and further, for example, resistors 40 and 42 of 1KΩ. Similarly, the amplifier 36 is a small resistor 4 of 100Ω.
The gate control signal is supplied to the gates of the IGBTs 14 and 16 via the resistor 4 and the resistors 46 and 48 of 1 KΩ, respectively. These elements 28 to 46 serve as control means for controlling the conduction and non-conduction states of the IGBT. Optical couplers 30 and 32 are used, and amplifiers 34 and 36 are used.
Note that since the reference potential of is coupled to the emitters of the IGBTs 10 (12) and 14 (16), the potential of the gate of the IGBT is floating from the delay circuit 28 and the potential is referenced to the emitter. I want to.

Next, the operation of FIG. 1 will be described with reference to FIGS. 2 shows the current (total IGBT current) flowing through the load with respect to the elapsed time, and FIG.
The general characteristic curve (collector-emitter voltage-collector current characteristic curve) of GBT10-16 is shown. In the steady state, the current flowing from the power source 18 through the load 20 is less than the excessive reference value, for example, Is, and therefore the voltage drop of the resistor 22 is also equal to or less than the reference voltage Vref.
Maintains a high level signal. This high level signal is supplied to amplifiers 34 and 36 via optical couplers 30 and 32, respectively. The amplifier 34 supplies a forward bias to the gates of the IGBTs 10 and 12 at their gates, so that the IGBTs 10 and 12 become conductive. Further, the amplifier 36 supplies a forward bias to the emitters of the IGBTs 14 and 16 at their gates, so that these IGBTs become conductive.

At time t0, if a short circuit or a ground fault occurs in the load 20, the current flowing through the load 20 will start to rise.
At this time, the operating point of the IGBT is the point P shown in FIG.
0. The current gradually increases at a slope (rate of increase) determined by the inductance and resistance of the current path of the load 20,
At time t1, the voltage drop across the resistor 22 changes to the reference voltage Vref.
The output signal of the comparator 26 changes to a low level. However, due to the action of the delay circuit 28, this low level is not immediately supplied to the gates of the IGBTs 10-16. Therefore, these IGBTs are still conductive.

At this time, due to the short circuit of the load 20, the IGBT
High voltage is applied to the collector, the collector current increases and
The operating point of T changes, and this operating point reaches P1. Therefore, the current flowing through the load 20 becomes a constant current Isat. Since the supply voltage is high, the operating point of the IGBT moves from P1 to the right side (higher voltage) along the operating curve, and the current is saturated.

Due to the delay action of the delay circuit 28, the time t2
At the low level propagates to the amplifiers 34 and 36,
When a low level is supplied to the gates of 10 to 16, these IGBTs sequentially shift to the non-conducting state. Note that time t2
Therefore, the operating point of the IGBT becomes P2. Therefore, the current flowing through the load 20 does not suddenly change from the rising state to the falling state as shown in FIG. 4, but gradually changes from the rising state to the descending state via a constant state as shown in FIG. To do. Therefore, spike noise and the like can be prevented.
By the way, in the above-described embodiment, the dedicated block 28 is provided as the delay circuit, but with the input capacitance of the IGBT,
A time constant circuit including the gate resistors 38 to 46 may be a delay circuit. In this case, the delay time can be adjusted by selecting the value of the gate resistor. Therefore, in the case of the embodiment, two of the dedicated delay circuit and the delay circuit of the gate resistor and the time constant circuit of the input capacitance of the IGBT are used.

Although the preferred embodiment of the present invention has been described above, various modifications and changes can be made without departing from the gist of the present invention. For example, the semiconductor element used in the breaker device may be a high breakdown voltage semiconductor other than the IGBT.
Further, in the embodiment, the semiconductor elements are arranged in 2 rows and 2 columns, however, according to the desired maximum current and maximum voltage, any m rows and n columns (m and n are integers of 1 or more) may be arranged. Good. Further, the detecting means for detecting the excessive current may be a method for detecting a magnetic field due to the current flowing in the current path of the load.

[0018]

As described above, according to the present invention, when the current flowing through the current path of the load is cut off, a sudden change in the current is prevented, so that spike noise can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram of a preferred embodiment of the present invention.

FIG. 2 is a time-current diagram illustrating the operation of the present invention.

FIG. 3 is a characteristic diagram of a semiconductor device for explaining the operation of the present invention.

FIG. 4 is a time-current diagram illustrating the operation of a conventional breaker device.

[Explanation of symbols]

 10, 12, 14, 16 Semiconductor element (IGBT) 18 Power supply 20 Load 22 Current detection resistor 24 Differential amplifier 26 Comparator 30, 32 Optical coupler

Front Page Continuation (72) Inventor Shunichi Matsuda 5-9-31 Kitashinagawa, Shinagawa-ku, Tokyo Inside Sony Tektronix Co., Ltd.

Claims (3)

[Claims] 1. A breaker device for shutting off a current path of a load when an excessive current flows through the load, wherein a semiconductor element having an output current path inserted in the current path of the load and a predetermined current path of the load. When detecting that a current or more has flowed, the output signal state is changed, and the semiconductor element is controlled to be conductive in the normal state, and when the output signal state of the detection means is changed, the semiconductor element is saturated. And a control means for controlling the semiconductor element to be in a non-conducting state. 2. The semiconductor device is an insulated gate bipolar transistor, and the control means includes a delay circuit that delays an output signal of the detection means, and the output signal of the delay circuit is the insulated gate bipolar transistor. The breaker device according to claim 1, wherein the breaker device is supplied to the gate of the transistor and is controlled to be in a non-conductive state. 3. In the semiconductor device, n insulated gate bipolar transistors are connected in parallel, and n sets of the parallel connection are connected in series (n and m are integers of 1 or more).
The breaker device according to claim 1, wherein: