JP4514278B2 - Semiconductor control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor control device that realizes protection when a short-circuit current flows from a DC voltage source by simultaneously connecting switching elements connected in series by using an inexpensive conductive material and an integrator.
[0002]
[Prior art]
In semiconductor control devices such as inverters, current detection is generally performed using a current transformer to detect a short-circuit current of a DC voltage source. Hereinafter, the outline of the prior art will be described with reference to FIG.
In FIG. 4, 1 is a DC voltage source, 2 and 3 are switching elements provided with anti-parallel diodes, and IGBTs or SI thyristors are used as the switching elements.
4 is an AC output terminal and 31 is a current transformer. The switching elements 2 and 3, the AC terminal 4, and the current transformer 31 indicate basic inverters, and when the inverter is a three-phase inverter, it is configured with three basic inverters.
[0003]
Reference numeral 32 denotes a gate control device for the switching elements 2 and 3. In normal inverter operation, the switching elements 2 and 3 are controlled so as not to be simultaneously conducted. However, if the switching elements 2 and 3 are simultaneously conducted for some reason, the DC voltage source 1 to the switching element 2 and the current transformer are controlled. 31. A closed circuit is formed through the switching element 3, and a short-circuit current flows.
Since such a short-circuit current may damage the switching elements 2 and 3, the current is detected by the current transformer 31, and if this current value is larger than a predetermined value, it is determined that the short-circuit current is flowing. Thus, it is a general control method to perform gate blocking on the switching elements 2 and 3 to prevent element destruction and the like.
[0004]
[Problems to be solved by the invention]
However, current transformers are generally expensive. In particular, there is a problem that a current transformer that does not saturate the iron core against an excessive direct current when the two upper and lower elements are conductive and the direct current voltage source is short-circuited becomes very expensive. there were.
In order to solve such a problem, the present invention realizes inexpensive power supply short-circuit detection using a conductive material and an integrator.
[0005]
[Means for Solving the Problems] In order to realize this, in the present invention, a series circuit composed of first and second switching elements each including an antiparallel diode and a conductive material is provided at both ends of a DC voltage source. A semiconductor unit connected to a polarity that is energized in a forward direction when the first and second switching elements are turned on; an integrator that receives a voltage that is a differential waveform of a current waveform extracted from both ends of the conductor; and an output of the integrator Comprises a short circuit detector for detecting that a predetermined value has been reached, and a gate control device having a function of stopping the gate signals of the first and second switching elements when the short circuit detector detects a short circuit. .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The details will be described below with reference to the drawings. FIG. 1 is a circuit diagram for explaining the present invention, in which 5 is a conductive material, 6 is an integrator, 7 is a short circuit detector, 8 is a gate signal stop device, and 9 is a gate control device for a switching element. . The same parts as those in FIG. 4 are denoted by the same reference numerals.
In this case, the basic inverter includes switching elements 2 and 3, an AC output terminal 4, and a conductive material 5.
[0007]
FIG. 2 shows current waveforms and the like of respective parts for explaining the operation of the present invention. Reference numeral 11 denotes a conductive material when the switching elements 2 and 3 are simultaneously turned on and the DC voltage source 1 is short-circuited. An inflowing current waveform, 12 is a voltage waveform generated between both ends of the conductive material.
Reference numeral 13 denotes an output waveform of the integrator that receives a voltage waveform generated between both ends of the conductive material.
That is, since the conductive material always has some inductance, the waveform taken out from both ends of the conductive material is a differential waveform of the current waveform 11. The output voltage of the integrator 5 having this voltage as an input integrates the differential waveform of the current waveform 11, and eventually the current waveform 11 is restored. This is the point of the present invention.
[0008]
Hereinafter, when the output of the integrator 6 reaches a predetermined value, the short circuit detector 7 generates an output, and as a result, the output is given to the gate signal stop device 8 and reaches the gate stop as in the conventional case.
As described above, according to the present invention, the short-circuit current of the DC voltage source can be restored without using an expensive current transformer by utilizing the floating inductance of the conductive material and combining with an integrator.
[0009]
In FIG. 1, the conductive material is inserted between the antiparallel diodes 2 and 3, but it goes without saying that the connection position may be on the collector side of the switching element 2 or on the emitter side of the switching element 3.
As the conductive material, a copper plate, an aluminum plate, a shunt, or the like is used.
[0010]
FIG. 3 shows another embodiment of the present invention, in which AC is supplied to a DC voltage source via a converter, and AC is obtained from the DC voltage source via an inverter. 25 is a switching element, 26 and 27 are conductive materials, and 28 is an inverter.
The gate control device to which the output of the conductive material is given is not shown, but the output of the conductive materials 26 and 27 is given to the gate signal stop device via the integrator and the short-circuit detector, and the operation reaches the gate block. Is the same as in FIG.
[0011]
In this case, when the switching elements 22 and 23 are turned on simultaneously, a short-circuit current flows from the DC voltage source 21 through the switching elements 22 and 23. Needless to say, the present invention is also applied to this case.
Although FIG. 3 shows the case of a single-phase converter, it is needless to say that the present invention can also be applied to a three-phase converter.
[0012]
【The invention's effect】
As described above, in the present invention, a floating inductance of a conductive material is used, and the voltage generated between both ends of the conductive material can be input to the integrator to restore the original current waveform. There is no need to use an expensive current transformer for current detection.
[Brief description of the drawings]
FIG. 1 is a circuit diagram for explaining the present invention.
FIG. 2 is an explanatory diagram showing a current waveform of each part of the present invention.
FIG. 3 is a circuit diagram showing another embodiment of the present invention.
FIG. 4 is a circuit diagram for explaining a conventional technique.
[Explanation of symbols]
1, 21 DC voltage source 2, 3, 22 to 25 Switching element 4 AC output terminals 5, 26, 27 Conductor 6 Integrator 7 Short-circuit detector 8 Gate signal stop device 9, 32 Gate control device
11 Short-circuit current waveform of DC voltage source
12 Voltage waveform across conductor
13 Integrator output waveform
28 Inverter

Claims (1)

A semiconductor in which a series circuit composed of a first and second switching elements and a conductive material having antiparallel diodes is connected to both ends of a DC voltage source with a polarity that allows current to flow in the forward direction when the first and second switching elements are conductive. A unit, an integrator that receives a voltage that is a differential waveform of a current waveform taken out from both ends of the conductive material, a short-circuit detector that detects that the output of the integrator has reached a predetermined value, and the short-circuit detector A semiconductor control device comprising a gate control device having a function of stopping gate signals of the first and second switching elements when a short circuit is detected.

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