JPS58165423A - Overcurrent preventing device for semiconductor switch - 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] This patent relates to an overcurrent prevention device for semiconductor switches.

Overcurrent prevention device for semiconductor switch is BBC silicon l1
vLta Handbook (BBC-8111zlum-8
tromr+ch't@r4andbuch),
It is disclosed in 1971 edition P286 to P289.

For example, a DC switch is used to interrupt the overcurrent.

The current component acts as an IJ-:X- criterion. As a means to prevent a long continuous overcurrent, a constant current tm** that limits the current to less than half the maximum allowable continuous current (tm**) can be used. If this power limit is exceeded, the current is cut off. In conventional overcurrent protection devices, the current flowing through a semiconductor switch is utilized. That is, the limit switch disconnects the circuit when this current exceeds a predetermined limit value. As a result, the semiconductor switch does not have to have a larger capacity than its rated value, and the fusion current is kept below the maximum current value during normal operation. However, with conventional devices, there is a risk that they may be accidentally shut off during normal operation. Furthermore, from the point of overcurrent detection! There is a problem with the time it takes to complete the disconnection. During this time, a short circuit current exceeding the value of the interrupt I#ILfI/ is likely to occur. For this reason, it is necessary to have a value that is higher than the rated value by Semiconductor Switch Co., Ltd. As a result, the choke coil, which is provided in series with the semiconductor switch as a current limiter, becomes larger. Increasing the size of the choke coil is disadvantageous in terms of cost.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an overcurrent prevention device for a semiconductor switch that can quickly detect an overcurrent of 11f/L occurring externally.

1.

According to this invention, the current can be instantaneously cut off by Kj1m by quickly externally detecting the overcurrent.

Since the current rise time between detection and cutoff of overcurrent is longer, there is no need to increase the size of the semiconductor switch and circuit board. Voltage detection by potential separation becomes very simple. The detection winding (auxiliary winding) of the cheek coil is connected in parallel to the choke coil, and the instrument transformer (separate transformer @) is made into a small lid.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a first embodiment of an overcurrent protection device for a semiconductor switch. A DC current IIG is connected between the positive input terminal l and the negative input terminal 2 of the one-quadrant DC control unit y). control uni.

h, D positive and negative poles, power terminals are indicated by reference numerals, mare. The positive input terminal 1 and the positive output terminal 3 are connected to each other through a semiconductor switch 5 and a series circuit of circuits 1, 2, and 3. Semiconductor '11 As the switch 5, for example, a transistor or a
: Arc controlled and extinguished rhinoceros 1. A lister is used - negative input terminal 2 and negative output terminal 4 are directly connected to each other! Connected.

The diode 1 is connected to the semiconductor switch 5 and the common connection point of the semiconductor switch 5 at the cathode, and the diode 1 is connected to the common connection point of the semiconductor switch 5 and the coil go.
In II, negative input terminal 2KWj! It is threaded. A load 8 is connected between output terminals 1 and 4. Load a has an inductive impedance component and a resistive impedance component, and may generate electromagnetic force (for example, load d is a drive motor).

The choke coil 6 acts to limit the current rising speed when a short circuit occurs between the output terminals 3 and 4. What is the current flowing through the - cupill 6 and load 8? It is shown in

The choke coil 6 has a detection winding of 1 m# to detect overcurrent at.
have. The output terminal of detection @ll# is connected to the limit switch (voltage indicator) 10fC. Limit switch 1#
controls the semiconductor switch 6 via the drive unit 11 on the output side. The drive unit receives the output signal A of the limit switch 10 and the normal drive signal 8 at the input terminal.

In normal operation, the choke coil 6 is connected in series with the load I, so the power drop in the choke coil Cr is small (due to the relatively large impedance of the load), and the current change rate - 1 is very small in normal operation. However, when shortening occurs between the output terminals 3 and 44, the entire circuit voltage is applied to the coil 6 where the current rate of change is very large. The voltage produced across the choke coil is detected by a detection circuit, and the measured voltage is detected by a limit switch 10. When the limit switch LED receives high voltage, it immediately sends an output signal to the control device =,)JJ. Accordingly, before the short-circuit current R exceeds the predetermined O layer disconnection level value, the line disconnection operation is already started. Voltage quickly indicates short-circuit current, so it is very effective to detect short-circuit voltage and short-circuit current (like a tortoise current measurement). The rounded current measurement for short circuit detection does not occur, so it is normal! Malfunctions due to overcurrent R, even if the current limit is exceeded, are avoided.

With reference to FIG. 2, a second embodiment of the overcurrent prevention device of the semiconductor switch will be explained. According to this embodiment, the primary winding of the detection transformer IJ is connected in parallel to the choke coil 6.

The secondary winding of the detection transformer J2 is a limit switch J)K*l!
When the high voltage is applied, the control unit (9) supplies an output signal to (31). The overcurrent protection device own capability is the same as the embodiment shown in Fig. 1.According to both the embodiments shown in Fig. 1 and S2, the choke coil 6
This method has the advantage that zero voltage measurement is a very simple method and can be performed regardless of potential.

The embodiment according to FIGS. 1 and 2 arises from the special circumstances of simple DC controllers with semiconductor switches. The overcurrent protection device can be effectively applied to the application field of semiconductor switches, 41 and 41 pulse modulation power control devices in control and drive technology.

□ Figure 3 shows a 4-quadrant DC controller and overcurrent in the case of
',,',:,,l″l,,:”',1'□...Example of the protection device is shown. Nine DC power supplies G are connected to each other.
1 and G2 are provided. The own terminal of the DC power supply 070 constitutes a positive terminal connected to the first semiconductor switch 5°-11 and the first main electrodes PL- and JK. DC power supply G10 free terminal is second half 5-2
9.2 conductor switch,
Chi [74 and 2nd Mayo Pyhiro on the other side
! Continued. These common points are 11! The 0 and 0 direct lines 11GJ, GJ+ID, which are connected to the positive output terminal 4 of the coil i0 and the terminal 4, are connected to the positive output terminal 1. Load 1 is applied between output terminals 1 and 4. The circuit d has a detection winding #, which is followed by a limit switch 10.

@field switch iao output signal and normal drive drive signal 8
is supplied with the control unit, t11fC, and ζO control unit 5=,
) JJ drives and controls the semiconductor r-1, 1g-2 body switches ', .

,,: The function of the overcurrent protection stirrup of No. 35i is as shown in Fig. 1, 4 people, 1,

[Brief explanation of the drawing]

1g is a circuit diagram of a portion of an overcurrent prevention device for a semiconductor switch according to another embodiment; The figure shows another example. S, 6, 1.15.1...Semiconductor switch, 6...
I...Load, I...Detection winding, 1
0... Limit switch, 11... Behavior any, ), 12
...detection transformer, G, 01. G! ...DC power supply.

Claims (1)

[Scope of Claims] (1) An overcurrent prevention device for a semiconductor switch that is provided with a means for cutting off an overcurrent flowing through a semiconductor switch that is provided in series with a choke coil that limits the speed of current rise. In this case, the choke coil (device (12) for detecting the voltage drop of the older sister) has a limit switch.
An overcurrent RM stop device for a semiconductor switch, which is connected to a trout, and is characterized by:
) The above-mentioned coils (Il) have a detection winding (9) for detecting voltage.
Conductor switch O' overcurrent stop device described in Sg 1, No. 1. (3) The semiconductor switch according to claim 1, wherein the choke coil (6) is connected in parallel to an instrument transformer for detecting voltage. overcurrent prevention device. (4) The limit switch Q4 is connected to the front side on the output side.
Claims 1 to 3 are characterized in that the driving means C11) of the semiconductor switch (5) are connected to each other.
Overcurrent prevention device for semiconductor switches as described in any of the above. −