JPS5979162A - Current detector - Google Patents

Abstract

PURPOSE:To attain a current detector superior in responsiveness, by inputting the analog output of a shunt resistance to the primary side of a pulse transformer, which is provided with switching elements in the primary side and the seconary side, to convert the input into a pulse and allowing this pulse to pass through a filter to convert it to an analog output. CONSTITUTION:A voltage V proportional to a current I to be measured is taken out by a resistance 2 and is applied to a switching element 6 through a filter 5. A control pulse P having a prescribed time width is inputted to the element 6 to perform the switching operation at intervals of a certain time, and therefore, a voltage of interrupted wave appears in the secondary side of a pulse transformer 8. Since elements 6 and 7 are synchronized with each other, this voltage passes through the switching element 7 as it is to charge a capacitor 14. Since the switching element 7 is turned off at the fall time, the capacitor 14 is not discharged and holds the charge voltage up to the following rise time, and thus, a detection signal having a waveform similar to the current I to be measured is taken out from an output terminal 18 and is insulated by the transformer and is used for a high voltage circuit.

Description

[Detailed description of the invention] The present invention relates to a current detector.

Traditionally, shunt resistors and DC transformers have been used in this type of warm current detector, but the former cannot be used in high-voltage circuits because it cannot be isolated from the main circuit through which the current to be measured flows. However, the latter has the drawbacks of poor responsiveness and detection accuracy, as well as being expensive.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional technology. inserted between the father and the primary 1tl
! By configuring the switching element of 1 and the oscillator that outputs the control pulse train to be electrically isolated,
It is an object of the present invention to provide a current detector that can be used in a high voltage circuit, has excellent rudder control, responsiveness, and can be manufactured at low cost.

Hereinafter, one part of this invention, the eave 1flll, will be explained with reference to the drawings.

In Figure 1, 1 is the conductor through which the current to be measured flows, 2
are shunt resistors; 3 and 4 are resistors and capacitors constituting the first filter 5; 6 and T are switching elements; and 8 is a pulse transformer. The switching element 6 is inserted between the primary winding rz of the pulse transformer 8 and the -F filter 5, and the switching element γ is connected in series with the secondary winding n2 of the pulse transformer 8. Reference numeral 9 denotes a pulse excavator which sends out a control pulse P as shown in FIG.
1 to the gate terminal of the switching element γ. 12 is an amplifier in which the output of the switching element r is connected to a second filter 1 consisting of a resistor 13 and a capacitor 14;
5. 16 and 17 are return stirrup resistances.

18 is an output terminal.

Next, the operation of this DC current detector will be explained with reference to FIG.

When the current I to be measured flows through the conductor 1, a voltage V proportional to the magnitude of the current I is taken out through the shunt resistor 2, and
The signal is applied to the switching element 6 via the filter 5 . Since the control pulse P with a predetermined time width t1 is input to the switching element 6 and the switching operation is performed every certain time ntt, the pulling pressure of the intermittent wave as shown in FIG. 2(e) is applied to the pulse transformer 8. appears on the secondary side of Since the switching element T opens and closes in the same way as the switching element 6, the voltage appearing on the secondary side of the pulse transformer 80 passes through the switching element T as it is and charges the capacitor 14.

Kameda in h note is an intermittent wave, but at the time of its falling, the switching element I is in the off-state width, so the capacitor 14 does not discharge and maintains the charged and constant pressure until the following rising point.
A detection signal having a waveform similar to the current I to be measured is taken out from the output terminal 18, as shown in FIG. 2(d). The positive degree of the detection signal of O is determined by both switching elements 6. This can be improved by increasing the switching speed of T.

As described above, according to the present invention, the analog output of the shunt resistor is inputted to the primary side of the pulse transformer, which is provided with switching elements that perform a switching operation on the primary and secondary sides, respectively, and pulsed. By using a configuration that passes the pulsed signal through a filter and outputs it as an analog signal,
4. Since the output 111t1 and the output 1111 are insulated by the pulse transformer, a current detector that can be used as a high T [output circuit] and has excellent response and integration can be obtained. be able to.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of a current detector according to the present invention, and FIG. 2 is a time chart of operation waveforms of various parts in the above embodiment. In the figure, 2... gloss resistor 6, γ... switching element 8, 10... pulse transformer 9... excavator 15... ····filter. Yuzu, in the figure, the number of times is &J, 1ij4-and the part corresponding to U is 336

Claims (1)

[Claims] Break l111 constant circuit! , f1, a 7-yant resistor, a first switching element receiving the output of the shunt resistor,
a first pulse transformer having the first switching element on its primary side;
a second switching element that opens and closes in synchronization with the switching element @2; a filter that smoothes the output of the switching element @2; Through G, 1st
The current detector is designed to be supplied to the switching elements of the current detector.