CN108872684A - A kind of novel passive AC current collecting circuit - Google Patents

Abstract

The invention discloses a novel passive AC current acquisition circuit, comprising first to third low-power coils, first to fourth resistors and high-precision transformers, the first low-power coil, the second low-power coil and The phase end of the third low-power coil is grounded and connected to one end of the primary coil of the high-precision transformer; the other end of the first resistor, the other end of the second resistor and the other end of the third resistor are connected, and The connecting ends of the first resistor, the second resistor and the third resistor are connected to the other end of the primary coil of the high-precision transformer; the fourth resistor is connected to the secondary coil of the high-precision transformer . The novel passive AC current collection circuit of the present invention can collect three-phase large current signals, convert the large current signals into small voltage signal outputs, and use hardware to synthesize a current zero sequence and convert it into a voltage signal, while ensuring the amplitude accuracy At the same time, the accuracy of the phase is also guaranteed.

Description

A New Passive AC Current Acquisition Circuit

technical field

The invention relates to a novel passive alternating current acquisition circuit.

Background technique

Conventional CT uses electromagnetic principle coils to output current signals, which have the disadvantages of not being able to open the circuit and being large in size. Moreover, conventional CTs need a separate zero-sequence current coil to produce zero-sequence, and the precision of this coil is difficult to make high.

Contents of the invention

The purpose of the present invention is to overcome the defects of the prior art and provide a novel passive AC current acquisition circuit, which can acquire three-phase high current signals, convert the large current signals into small voltage signal outputs, and synthesize a current zero by hardware sequence and convert it into a voltage signal, while ensuring the accuracy of the amplitude, it also ensures the accuracy of the phase.

The technical solution to achieve the above purpose is: a new passive AC current acquisition circuit, including the first to third low-power coils, the first to fourth resistors and high-precision transformers, wherein:

One end of the first low-power coil, one end of the second low-power coil and one end of the third low-power coil are connected, and the connection of the first low-power coil, the second low-power coil and the third low-power coil The end is grounded and connected to one end of the primary coil of the high-precision transformer;

The other end of the first low-power coil, the other end of the second low-power coil and the other end of the third low-power coil are in one-to-one correspondence with one end of the first resistor, one end of the second resistor and the third resistor connected at one end;

The other end of the first resistor, the other end of the second resistor and the other end of the third resistor are connected, and the connecting ends of the first resistor, the second resistor and the third resistor are connected to the high-precision transformer the other end of the primary coil;

The fourth resistor is connected to the secondary coil of the high-precision transformer.

The above-mentioned novel passive AC current collection circuit, wherein the first low-power coil is connected in series with the first resistor, collects the A-phase positive-sequence current signal, and converts the A-phase positive-sequence current signal into a voltage signal for output;

The second low-power coil is connected in series with the second resistor to collect the B-phase positive-sequence current signal, and convert the B-phase positive-sequence current signal into a voltage signal for output;

The third low-power coil is connected in series with the third resistor to collect a C-phase positive sequence current signal, and convert the C-phase positive sequence current signal into a voltage signal for output;

The secondary coil of the high-precision transformer is connected in parallel with the fourth resistor to collect a zero-sequence current value and convert the zero-sequence current value into a voltage signal for output.

The new passive AC current acquisition circuit of the present invention collects three-phase large current signals, converts the large current signals into small voltage signal outputs, and uses hardware to synthesize a current zero sequence and converts it into a voltage signal, while ensuring the accuracy of the amplitude At the same time, the accuracy of the phase is also guaranteed

Description of drawings

Fig. 1 is the circuit diagram of the novel passive alternating current acquisition circuit of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the technical solution of the present invention, its specific implementation will be described in detail below in conjunction with the accompanying drawings:

Please refer to Fig. 1, the best embodiment of the present invention, a new passive AC current acquisition circuit, including first to third low-power coils, first to fourth resistors and high-precision transformer CT0.

One end of the first low power coil CTA, one end of the second low power coil CTB and one end of the third low power coil CTC are connected, and the first low power coil CTA, the second low power coil CTB and the third low power coil CTC The phase-connected end is grounded and connected to one end of the primary coil of the high-precision transformer CT0; the other end of the first low-power coil CTA, the other end of the second low-power coil CTB, and the other end of the third low-power coil CTC correspond one-to-one The ground is connected to one end of the first resistor R _ia , one end of the second resistor R _ib and one end of the third resistor R _ic ; the other end of the first resistor R _ia , the other end of the second resistor R _ib and the third resistor R _ic The other end of the resistor R _ia , the second resistor R _ib and the third resistor R _ic are connected to the other end of the primary coil of the high-precision transformer CT0; the fourth resistor R _I0 is connected to the high-precision On the secondary coil of transformer CT0.

In the novel passive AC current acquisition circuit of the present invention, the first low-power coil CTA is connected in series with the first resistor R _ia to collect the phase A positive sequence current signal I _A , and convert the phase A positive sequence current signal I _A into a voltage The signal U _Ia is output; the second low-power coil CTB is connected in series with the second resistor R _ib to collect the B-phase positive sequence current signal I _B , and convert the B-phase positive sequence current signal I _B into a voltage signal U _Ib output; the third low-power The power coil CTC is connected in series with the third resistor R _ic to collect the C-phase positive sequence current signal I _C , and convert the C-phase positive sequence current signal I _C into a voltage signal U _Ic for output; the first resistor R _ia and the second resistor R _ib The connecting end of the third resistor R _ic is connected to the primary coil of the high-precision transformer CTO, and the secondary coil of the high-precision transformer CTO is connected in parallel with the fourth resistor RI0 to collect the zero-sequence current value and convert the zero-sequence current value It is the voltage signal U _I0 output.

In a kind of novel passive alternating current acquisition circuit of the present invention:

(1) Using low-power coils, and converting current signals into voltage signals, there is no open circuit problem, and the volume is greatly reduced;

(2) No separate zero-sequence current coil is needed, and the zero-sequence current value is collected by means of hardware synthesis, that is, the high-precision transformer CTO is connected to the resistor, and the zero-sequence current value is converted into a voltage signal output, saving space, and The precision can be very high;

(3) Using voltage signal output, the wiring and cables on the controller side can use thin wires, which is convenient for wiring.

In summary, the novel passive AC current acquisition circuit of the present invention can acquire three-phase high-current signals, convert the high-current signals into small voltage signal outputs, and use hardware to synthesize a current zero-sequence and convert it into a voltage signal. While ensuring the accuracy of the amplitude, the accuracy of the phase is also guaranteed.

Those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present invention, rather than as a limitation to the present invention, as long as within the scope of the spirit of the present invention, the above-described embodiments Changes and modifications will fall within the scope of the claims of the present invention.

Claims (2)

1. a kind of novel passive AC current collecting circuit, which is characterized in that including first~third low-power coil, first~ 4th resistance and high-precision mutual inductor, wherein：

One end of the first low-power coil, the second low-power coil one end be connected with one end of third low-power coil, And the abutment end of the first low-power coil, the second low-power coil and third low-power coil is grounded and accesses described high-precision Spend one end of the primary coil of mutual inductor；

The other end of the other end of the first low-power coil, the other end of the second low-power coil and third low-power coil It is connected correspondingly with one end of one end of the first resistor, one end of second resistance and 3rd resistor；

The other end, the other end of second resistance of the first resistor are connected with the other end of 3rd resistor, and first electricity The abutment end of resistance, second resistance and 3rd resistor accesses the other end of the primary coil of the high-precision mutual inductor；

4th resistance is connected on the secondary coil of the high-precision mutual inductor.

2. a kind of novel passive AC current collecting circuit according to claim 1, which is characterized in that the first low function Rate coil and first resistor series connection, acquire A phase forward-order current signal, and it is defeated that A phase forward-order current signal is converted to voltage signal Out；

The second low-power coil and second resistance series connection, acquire B phase forward-order current signal, and by B phase forward-order current signal Be converted to voltage signal output；

The third low-power coil and 3rd resistor series connection, acquire C phase forward-order current signal, and by C phase forward-order current signal Be converted to voltage signal output；

The secondary coil of the high-precision mutual inductor and the 4th resistor coupled in parallel, acquire zero-sequence current value, and by zero-sequence current Value is converted to voltage signal output.