CN1053498A - A kind of current sensor - Google Patents

Abstract

The invention provides a kind of detect the AC and DC current signal, particularly a kind of detect such as complicated wave form current signals such as pulsating current and pulse current and accuracy of detection is high and safe and reliable current sensor, it is the non-contact current sensor that adopts the magnetic compensation method to make, and its structure comprises insulation crust, poly-magnetic system and sensor circuit.

Description

A kind of current sensor

The invention belongs to power electronics detector for measuring part.

Current sensor is used for obtaining the current signal of circuit-under-test, and detected current signal is presented to display, protector or varitrol, apparatus is carried out parameter show, protect automatically and control automatically.Common current sensor fibrous root is according to its different purpose classification manufacturings.The alternating current-direct current sensor can not replace mutually, measures class and can not replace mutually with the protection class, and be only applicable to the measurement and the protection of direct current or interchange 50HZ sine wave.But very difficult for application such as complicated wave forms such as pulsating current, pulse currents, simultaneously, its precision low (ratio difference is generally in ± 1%-± 3% scope, phase differential is 60 '-180 ' interior) will be carried out accurate measurement, analyze system and device is carried out accurately comparatively difficulty of control automatically.In addition, this class current sensor also has a major defect: when secondary circuit produced open fault, one time magnetic potential was all used excitation, and the iron core degree of depth is saturated, and induced potential is a peaked wave, and Secondary Winding will produce dangerous superpotential.Equipment and personal safety are constituted a serious threat.

The purpose of this invention is to provide a kind of examine AC and DC current signal then, particularly a kind of detect such as complicated wave form current signals such as pulsating current and pulse current and accuracy of detection is high and safe and reliable current sensor.

Embodiments of the present invention are to use hall principle, adopt the magnetic compensation method to make non-contact current sensor.Followingly be described in detail in conjunction with the accompanying drawings.

Fig. 1 is the product structure figure of invention, and Fig. 2 is a circuit structure diagram.Wherein 1 represents brass screw, the coil of 2 expression band skeletons, and 3 expression hall devices, 4 expression iron cores, 5 represent insulation crusts, the circuit board of 6 expression band elements.

This product is made up of printed circuit board 6 three parts of insulation crust 5, poly-magnetic system and band components and parts.Wherein insulation crust is made up of housing and cover plate, and there is a rectangular through holes at its middle part, the usefulness of passing as main circuit (primary current) lead.Poly-magnetic system is made of the air core coil 2 and the hall device 3 of siliconized plate magnetism gathering rings, band plastic skeleton, coil rack has two sipes, and a slit is left in the centre, and enameled wire evenly is wound in two sipes respectively, hall device places slit central authorities, and magnetism gathering rings inserts in the skeleton square hole.Printed circuit board (its circuit structure is seen below and stated) is fixed in the insulation booth bottom guide track, end at printed circuit board has some leads, make circuit in the printed circuit board and coil, hall device and electric current (volt power supply for example ± 15, some brass screws inputs from the shell) be connected, see shown in Figure 1.The following inventive circuit structure and the course of work thereof are carried out division.

1. the function of each element in the circuit structure (see figure 2):

(1) holding circuit: D1, D2, D3, D4 form holding circuit and prevent the external power supply error-polarity connection and damage the circuit elements device;

(2) constant-current power supply circuit: BG1, R7, R8 form constant-current supply, supply with hall device and make current source;

(3) Hall voltage generator: HR obtains a steady current by R1, R2, and when its vertical plane had magnetic field and have the magnetic line of force to pass through, 3,4 pin promptly produced Hall voltage, presented to amplifier;

(4) operational amplifier: the Hall voltage that HR is sent here carries out the signal amplification by the anti-phase respectively and noninverting input of R5, R6 IC;

(5) current-limiting resistance: R1, R2 make current-limiting resistance and use;

(6) current potential is adjusted the DC potential that resistance: R3, R4 adjust IC;

(7) voltage amplifier: BG2, BG3, R9, R10 constitute voltage amplifier;

(8) power amplifier: BG4, BG5, R11, R12 constitute power amplifier;

(9) the telefault L of ribbon core: when electric current flows through, generation one and the opposite magnetic field of external circuit (major loop-primary current);

(10) filter capacitor C1: make power filter and use;

(11) series connection vibrationproof absorption circuit: C3, R13 and C4, R14 constitute two groups of series connection vibrationproof absorption circuit respectively;

(12) negative feedback capacitor C2;

2, the course of work:

When major loop (former limit circuit) has intensity is that the electric current (be through in the oblong aperture of insulation booth center in the bus electric current) of IN is when passing through, learn according to stupefied thatch theorem, around lead, will produce the magnetic field H of respective strengths, its direction and hall device (HR) plane is perpendicular, and promptly 2,4 ends at HR induce Hall voltage EHR.Because the linear relationship of HR, the size of EHR is proportional to IN, through IC, BG2(BG3), BG4(BG5) error, voltage, the power amplifier that can form amplify, and makes telefault L obtain electric current I L.This electric current I L will produce magnetic field H 1, and its intensity equates that with H direction is opposite, i.e. H=-H1.Both cancel each other, thereby reach the detection effect of zero magnetic flux.

Because the linear relationship of HR, the electric current that flows through coil L is proportional to major loop (former limit) electric current I N:IL=nIN.On the resistance R L that external positive-negative power common port M is connected in series, detect its voltage drop value VL again.According to Ohm law V=IR, can obtain electric current (IL) intensity of flowing through coil.Can learn the intensity of main circuit current by formula: IN=1/n * V2/RL.

And because the circuit reaction velocity is exceedingly fast, electric current is correctly followed fast and linearity height, and secondary current waveform can fully truly reflect former limit main circuit current waveform.

Characteristics of the present invention and excellent results are as follows:

(1) is applicable to measurement, the analysis of direct current, interchange, pulsating current and impulse waveform; Secondary current reflects the primary current waveform truly, and the particularly suitable complicated wave form is analyzed;

(2) dynamic perfromance is good.Circuit response time is fast, correctly follows the speed height;

(3) reliable, overload capacity of working stability and strong interference immunity.Even former limit is main when postbacking living short trouble, product is not damaged yet;

(4) precision height, the linearity are good;

(5) working band is wide;

(6) mutually insulated between former limit and secondary circuit;

(7) owing to using epoxy sealing, can be in operate as normal under the rugged surroundings;

(8) physical dimension is little, and is in light weight, is convenient to install and use.

Claims (1)

1, a kind of current sensor is made up of insulation crust, poly-magnetic system and sensor circuit, it is characterized in that this sensor circuit is composed as follows:

A, prevent the external power supply error-polarity connection and damage the holding circuit of circuit elements device by what D1, D2, D3, D4 formed;

B, the constant-current power supply circuit of forming by BG1, R7, R8;

C, Hall voltage generator HR;

D, operational amplifier IC;

E, current-limiting resistance R1, R2;

F, current potential are adjusted resistance R 3, R4;

G, the voltage amplifier of forming by BG2, BG3, R9, R10;

H, the power amplifier of forming by BG4, BG5, R11, R12;

The telefault L of i, ribbon core;

J, filter capacitor C1;

K, two groups of series connection vibrationproof being made up of C3, R13, C4, R14 absorb circuit;

L, negative feedback capacitor C2.