阅读说明：本技术 一种用于无源二次回路检查源的三相保护电路 (Three-phase protection circuit for passive secondary circuit inspection source ) 是由 张伍 白福庆 于 2020-07-03 设计创作，主要内容包括：本发明公开了一种用于无源二次回路检查源的三相保护电路,包括A相交流电流取样单元、B相交流电流取样单元、C相交流电流取样单元、A相电流上下限比较单元、B相电流上下限比较单元和C相电流上下限比较单元,A相交流电流取样单元、B相交流电流取样单元和C相交流电流取样单元分别包括取样电阻、电流运算放大器MAX9920A和直流电源+VCC2与-VCC2,A相电流上下限比较单元、B相电流上下限比较单元和C相电流上下限比较单元分别包括两路比较器、上限阀值Lim-H、下限阀值Lim-L、直流电源+VCC1与-VCC1、输出上拉电源+VDD和报警输出信号。本发明电路简单,信号隔离,采样比例可调,精度高,线性度好,响应速度快,电阻采样无延时,体积小。(The invention discloses a three-phase protection circuit for a passive secondary circuit check source, which comprises an A-phase alternating current sampling unit, a B-phase alternating current sampling unit, a C-phase alternating current sampling unit, an A-phase current upper and lower limit comparison unit, a B-phase current upper and lower limit comparison unit and a C-phase current upper and lower limit comparison unit, wherein the A-phase alternating current sampling unit, the B-phase alternating current sampling unit and the C-phase current sampling unit respectively comprise a sampling resistor, a current operational amplifier MAX9920A and a direct current power supply + VCC2 and-VCC 2, and the A-phase current upper and lower limit comparison unit, the B-phase current upper and lower limit comparison unit and the C-phase current upper and lower limit comparison unit respectively comprise two-path comparators, an upper limit threshold Lim-H, a lower limit threshold Lim-L, a direct current power supply + VCC1 and-VCC 1, and output. The invention has the advantages of simple circuit, signal isolation, adjustable sampling proportion, high precision, good linearity, high response speed, no time delay of resistance sampling and small volume.)

1. A three-phase protection circuit for a passive secondary circuit inspection source comprises an A-phase alternating current sampling unit (1), a B-phase alternating current sampling unit (2), a C-phase alternating current sampling unit (3), an A-phase current upper and lower limit comparison unit (4), a B-phase current upper and lower limit comparison unit (5) and a C-phase current upper and lower limit comparison unit (6), and is characterized in that the A-phase alternating current sampling unit (1), the B-phase alternating current sampling unit (2) and the C-phase alternating current sampling unit (3) respectively comprise sampling resistors, a current operational amplifier MAX9920A and a direct current source + VCC2 and-VCC 2, and the A-phase current upper and lower limit comparison unit (4), the B-phase current upper and lower limit comparison unit (5) and the C-phase current upper and lower limit comparison unit (6) respectively comprise two comparators, and upper limit threshold Lim-H, The lower limit threshold Lim-L, the direct current power supply + VCC1 and-VCC 1, the output pull-up power supply + VDD and the alarm output signal.

2. A three-phase protection circuit for a passive secondary loop check source as claimed in claim 1, the device is characterized in that a current signal of a measured current of the A-phase alternating current sampling unit (1) is input into a MAX9920A current operational amplifier through a sampling resistor, the MAX9920A current operational amplifier isolates the input current signal, the input current signal is converted to an output end signal OVLA in proportion and is output to an A-phase current upper and lower limit comparison unit (4), the A-phase current upper and lower limit comparison unit (4) monitors and compares an OVLA signal exceeding an upper limit and an overcurrent state in real time according to a current upper limit threshold Lim-H, the A-phase current upper and lower limit comparison unit (4) monitors and compares an OVLA signal being smaller than a lower limit and an overcurrent state according to a lower limit threshold Lim-L, and the A-phase current upper and lower limit comparison unit (4) outputs an alarm signal IA-BJ once the;

in a similar way, the B-phase alternating current sampling unit (2) and the B-phase current upper and lower limit comparison unit (5) work in a matched mode, monitor the B-phase current and output an alarm signal IB-BJ;

in the same way, the C-phase alternating current sampling unit (3) and the C-phase current upper and lower limit comparison unit (6) work in a matched mode, the C-phase current is monitored, and an alarm signal IC-BJ is output.

3. The three-phase protection circuit for the passive secondary loop check source of claim 1, wherein three phases of the detected currents in the circuits of the A AC current sampling unit (1), the B AC current sampling unit (2) and the C AC current sampling unit (3) pass through sampling resistors to obtain A, B and C three-phase input signals IFA1, IFA2, IFB1, IFB2, IFC1 and IFC2, and the A, B and C three-phase output signals OVLA, OVLB and OVLC are output to the current comparison unit after three-way current operational amplifier conversion.

4. The three-phase protection circuit for the passive secondary circuit inspection source according to claim 1, wherein the three-phase input signals OVLA, OVLB and OVLC of the circuits of the phase a current upper and lower limit comparison unit (4), the phase B current upper and lower limit comparison unit (5) and the phase C current upper and lower limit comparison unit (6) are input into the upper and lower limit comparison unit, the comparison unit monitors the overrun state of the input signals according to the upper and lower limit thresholds Lim-H and Lim-L, and generates corresponding three-phase alarm output signals IA-BJ, IB-BJ and IC-BJ once the input signals exceed the upper and lower limit thresholds.

Technical Field

The invention relates to the field of circuits, in particular to a three-phase protection circuit for a passive secondary circuit inspection source.

Background

The three-phase program-controlled precision test power supply is a new generation high-precision standard power source composed of a DSP (digital signal processor) based on 1.2GMAC (digital signal processor), a large-scale FPGA (field programmable gate array), a high-speed high-precision DA (digital-analog) and a high-fidelity power amplifier, is suitable for power departments and enterprises which need measurement, inspection and high-precision standard signal sources, such as electrical measurement, thermal engineering, telemechanical, scheduling and the like of a power system, and is also suitable for occasions which need the high-precision standard signal sources to measure and inspect.

Disclosure of Invention

The present invention is directed to a three-phase protection circuit for a passive secondary circuit inspection source, which solves the above-mentioned problems of the prior art.

In order to achieve the purpose, the invention provides the following technical scheme: a three-phase protection circuit for a passive secondary circuit inspection source comprises an A-phase alternating current sampling unit, a B-phase alternating current sampling unit, a C-phase alternating current sampling unit, an A-phase current upper and lower limit comparison unit, a B-phase current upper and lower limit comparison unit and a C-phase current upper and lower limit comparison unit, wherein the A-phase alternating current sampling unit, the B-phase alternating current sampling unit and the C-phase current sampling unit respectively comprise a sampling resistor, a current operational amplifier MAX9920A and a direct current power supply + VCC2 and-VCC 2, and the A-phase current upper and lower limit comparison unit, the B-phase current upper and lower limit comparison unit and the C-phase current upper and lower limit comparison unit respectively comprise two-path comparators, an upper limit threshold Lim-H, a lower limit threshold Lim-L, a direct current power supply + VCC1 and-VCC 1, and output pull-up.

Preferably, the current to be measured of the A-phase alternating current sampling unit passes through a sampling resistor to input a current signal into a MAX9920A current operational amplifier, the MAX9920A current operational amplifier isolates the input current signal, the input current signal is converted to an output end signal OVLA in proportion and output to an A-phase current upper and lower limit comparison unit, the A-phase current upper and lower limit comparison unit monitors and compares an OVLA signal exceeding an upper limit and an overcurrent state in real time according to a current upper limit threshold Lim-H, the A-phase current upper and lower limit comparison unit monitors and compares the OVLA signal being smaller than a lower limit and the overcurrent state according to a lower limit threshold Lim-L, and the A-phase current upper and lower limit comparison unit outputs an alarm signal IA-BJ once the A-;

similarly, the B-phase alternating current sampling unit and the B-phase current upper and lower limit comparison unit work in a matching way, monitor the B-phase current and output alarm signals IB-BJ;

in a similar way, the C-phase alternating current sampling unit and the C-phase current upper and lower limit comparison unit work in a matched mode, the C-phase current is monitored, and an alarm signal IC-BJ is output.

Preferably, the three-phase tested currents in the circuits of the a-phase alternating current sampling unit, the B-phase alternating current sampling unit and the C-phase alternating current sampling unit are input to the input end of the current operational amplifier through the sampling resistors to obtain a, B and C three-phase input signals IFA1, IFA2, IFB1, IFB2, IFC1 and IFC2, and are converted by the three-phase current operational amplifier to obtain a, B and C three-phase output signals OVLA, OVLB and OVLC which are output to the current comparison unit.

Preferably, three-phase input signals OVLA, OVLB and OVLC in the circuits of the phase-A current upper and lower limit comparison unit, the phase-B current upper and lower limit comparison unit and the phase-C current upper and lower limit comparison unit are input into the upper and lower limit comparison unit, the comparison unit monitors the overrun state of the input signals according to upper and lower limit threshold values Lim-H and Lim-L, and corresponding three-phase alarm output signals IA-BJ, IB-BJ and IC-BJ are generated once the input signals exceed the upper and lower limit threshold values.

The invention has the technical effects and advantages that:

the A alternating current sampling unit, the B alternating current sampling unit and the C alternating current sampling unit have the advantages that: the circuit is simple, the signal is isolated, the sampling proportion is adjustable, the precision is high, the linearity is good, the response speed is high, the resistance sampling is free of time delay and small in size, and the A-phase current upper and lower limit comparison unit, the B-phase current upper and lower limit comparison unit and the C-phase current upper and lower limit comparison unit have the advantages that the circuit is simple, the upper and lower limit threshold values are monitored simultaneously, the alarm output low level is effective, the cost is low, and the speed is high.

Drawings

Fig. 1 is a circuit diagram of a three-phase protection circuit of the present invention.

Fig. 2 is a circuit diagram illustrating the operation principle of the present invention.

In the figure: 1. a alternating current sampling unit; 2. b, an alternating current sampling unit; 3. a C alternating current sampling unit; 4. an A-phase current upper and lower limit comparing unit; 5. a B-phase current upper and lower limit comparing unit; 6. c phase current upper and lower limit comparing unit.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a three-phase protection circuit for a passive secondary circuit inspection source as shown in FIGS. 1-2, which comprises an A-phase alternating current sampling unit 1, a B-phase alternating current sampling unit 2, a C-phase alternating current sampling unit 3, an A-phase current upper and lower limit comparison unit 4, a B-phase current upper and lower limit comparison unit 5 and a C-phase current upper and lower limit comparison unit 6;

the working principle refers to fig. 2, wherein:

a-phase alternating current sampling unit 1: the detected current passes through a sampling resistor to input a current signal into a MAX9920A current operational amplifier, the MAX9920A current operational amplifier isolates an input current signal, the input current signal is converted to an output end signal OVLA according to a proportion and is output to an A-phase current upper and lower limit comparison unit 4, the A-phase current upper and lower limit comparison unit 4 monitors and compares an OVLA signal exceeding an upper limit and an overcurrent state in real time according to a current upper limit threshold Lim-H, the A-phase current upper and lower limit comparison unit 4 monitors and compares the OVLA signal being smaller than a lower limit and the overcurrent state according to a lower limit threshold Lim-L, and the A-phase current upper and lower limit comparison unit 4 outputs an alarm signal IA-BJ once the detected current;

similarly, the B-phase alternating current sampling unit 2 and the B-phase current upper and lower limit comparison unit 5 work in a matching mode, monitor the B-phase current and output alarm signals IB-BJ;

in a similar way, the C-phase alternating current sampling unit 3 and the C-phase current upper and lower limit comparison unit 6 work in a matched mode, the C-phase current is monitored, and an alarm signal IC-BJ is output;

the circuit composition of the A alternating current sampling unit 1, the B alternating current sampling unit 2 and the C alternating current sampling unit 3 is as shown in FIG. 2, and the circuit composition is composed of a sampling resistor, a current operational amplifier MAX9920A and a direct current power supply + VCC2 and-VCC 2, three-phase input signals IFA1, IFA2, IFB1, IFB2, IFC1 and IFC2 of a three-phase tested current are input to a current operational amplifier input end, and three-phase output signals OVLA, OVLB and OVLC are output to a current comparison unit after three-way current operational amplifier conversion;

the advantages are that: the circuit is simple, the signal is isolated, the sampling proportion is adjustable, the precision is high, the linearity is good, the response speed is high, the resistance sampling has no time delay, and the volume is small;

the circuit composition of the phase a current upper and lower limit comparing unit 4, the phase B current upper and lower limit comparing unit 5 and the phase C current upper and lower limit comparing unit 6 is shown in fig. 2: three phases respectively consist of two comparators, an upper limit threshold Lim-H, a lower limit threshold Lim-L, a direct current power supply + VCC1 and-VCC 1, an output pull-up power supply + VDD and an alarm output signal, three-phase input signals OVLA, OVLB and OVLC are input into an upper limit comparison unit and a lower limit comparison unit, the comparison unit monitors the overrun state of the input signals according to the upper limit threshold Lim-H and the Lim-L, and once the input signals exceed the upper limit threshold and the lower limit threshold, corresponding three-phase alarm output signals IA-BJ, IB-BJ and IC-BJ are generated;

the advantages are that: the circuit is simple, the upper and lower limit threshold values are monitored simultaneously, the alarm output is effective at a low level, the cost is low, and the speed is high.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.