CN201242561Y - Apparatus for detecting power supply current - Google Patents

Abstract

The utility model relates to a supply current detecting device which comprises a current transformer; wherein the current transformer comprises an original edge and a detecting edge, and the original edge is connected with a current shunting element in parallel. Adopting a way that two pins at the original edge of the rated low power current transformer are connected with a current shunting conductor in parallel, the supply current detecting device realizes achieves testing the heavy current through an existing low power current transformer, thereby effectively reducing the weight and volume of the electric and electronic equipment, lowering cost and reducing loss of the system.

Description

The source current pick-up unit

Technical field

The utility model relates to the source current pick-up unit, more particularly, relates to a kind of source current pick-up unit.

Background technology

Along with the progress and the demands of social development of Power Electronic Technique, at present for the demand of power electronic equipment, the annual growth in the whole world is suitable considerable, thereby drives the fast development of power electronic equipment manufacturer.But along with people for energy-conservation growth of requirement, the power electronic equipment of traditional various power frequency levels is just replaced by High-frequency machine in fast speed.High-frequency machine is with respect to the power frequency machine, is suitable outstanding at a lot of aspect of performances,, high power density little as volume, low noise, high-level efficiency, low cost etc.; And from working as to come, the supply unit part of nearly all electric appliance and electronic equipment has all adopted Switching Power Supply.Switching Power Supply is a kind of power electronic equipment that direct supply is provided for computing machine, communication and home electronics.Obtained application more and more widely in fields such as industry, communication, aerospace, military project and family lives.

No matter but be in original power frequency machine or the control of the system of present High-frequency machine, this physical quantity of electric current is quite a key and an important controlled quentity controlled variable.So before power electronic equipment design, the determining to seem of electric current detecting method stood in the breach.More general the having of detection method utilization of estimated current: Hall, current transformer and shunt etc.With regard to these three kinds of main flow detection methods,, relative merits are arranged respectively in response to different with requirement with occasion; But they have a common drawback, and that is exactly that its volume and cost all increase along with the continuous increase that detects range of current, and design brings inconvenience to total system; The developing direction of particularly present high power density and modularization power electronic equipment requires current detecting removing on the miniature basis of pick-up unit volume, and cost also requires cheap.As be depicted as traditional current transformer model at figure, 1 and 2 is former limit, and 3 and 4 for detecting the limit.Establish primary current this moment is I ₁₂, the former limit number of turn is N ₁₂, secondary current is I ₃₄, the secondary number of turns is N ₃₄, then have following relation:

$\frac{N_{12}}{N_{34}}=\frac{I_{34}}{I_{12}}---\left(1\right)$

This moment is because all electric currents will be flow through in former limit, so require the diameter of lead will satisfy the requirement of big electric current, the more important thing is simultaneously that magnetic core among Fig. 1 is wanted can not be saturated, otherwise the one, measure inaccurate, Another reason is that the saturated meeting of long-term magnetic core is gathered heat, dispelling the heat can cause current transformer to burn when bad, causes the control system collapse, even major accident takes place.Want enough big so detect big current requirements magnetic core with this current transformer, thus the increase that brings the volume and the cost of power supply.So find a kind of new power current detection method just to seem quite important and urgent.

The utility model content

The technical problems to be solved in the utility model is that the saturated defective that causes current transformer to burn of the former limit of above-mentioned detection high-current inductor magnetic core at prior art provides a kind of source current pick-up unit that has added vent diverter on the former limit of inductor.

The technical scheme that its technical matters that solves the utility model adopts is: construct a kind of source current pick-up unit, comprise current transformer, described current transformer comprises former limit and detects the limit that described former limit is parallel with vent diverter.

In source current pick-up unit described in the utility model, described vent diverter is a resistance.

In source current pick-up unit described in the utility model, described resistance is a plurality of, and a plurality of described resistance are parallel with one another.

In source current pick-up unit described in the utility model, the proportional range of described vent diverter and described former limit sense shunting is less than 10:1.

In source current pick-up unit described in the utility model, described source current pick-up unit also comprises the computing module of calculating actual current according to detected galvanometer, and the primary coil number of turn is N ₁₂, the coil turn that detects the limit is N ₃₄, the resistance of former limit and vent diverter is respectively R ₁₂With R ｀ ₁₂, the electric current that the detection frontier inspection measures is I ₂, then actual current I is: I=I ₂* (1+R ₁₂/ R ｀ ₁₂) * N ₃₄/ N ₁₂

Implement source current pick-up unit of the present utility model, has following beneficial effect: because two pins of source current pick-up unit of the present utility model on the former limit of specified small power electric current transformer come mode of dividing current conductor in parallel, reach and utilize existing low power current transformer to measure the method for big electric current, effectively reduced the weight and volume of power electronic equipment, reduce cost, reduced the loss of system.

Description of drawings

The utility model is described in further detail below in conjunction with drawings and Examples, in the accompanying drawing:

Fig. 1 is the structural representation of traditional source current pick-up unit;

Fig. 2 is the structural representation of source current pick-up unit of the present utility model.

Embodiment

As shown in Figure 2, add one minute current conductor R, R and N the pin one on former limit and 2 ₁₂Form relation in parallel, but the actual branch current conductor that increases newly the magnetic core of current transformer therewith there is no the relation of electromagnetism aspect, divide the current relationship on current conductor and former limit to depend on their the water conservancy diversion area ratio and the resistance of branch current conductor fully, the material of branch current conductor can be the same with the conductor on former limit, also can select for use different conductor to constitute.No matter whether added shunting conductor material is the same with the material on former limit on the pin of former limit, final detectable size of current is determined by the resistance sizes of minute current conductor: if promptly the resistance on former limit is R ₁₂, dividing the resistance of current conductor is R ₁₂, the rated current that former limit allows to flow through is I ₁₂, then reality can detect electric current and is:

$I=(1+\frac{R_{12}}{R_{12}^{\′}})\×I_{12}---\left(2\right)$

The maximum rated primary current of current transformer shown in Figure 1 is 30A, if former limit 1 with 2 pins and on a conductor identical with former sapwood material, the length of supposing conductor is the same with the length of former limit conductor, the cross-sectional area of conductor is 3 times of the former limit of current transformer for this reason, and then actual maximum can detected electric current be 30+30*3=120A; It is specified maximum detection electric current is become 120A by original 30A electric current.The method can realize utilizing the current transformer of existing small rated currents to detect big electric current, for the requirement of accuracy of detection, uniquely determines according to the relation between the resistance of minute current conductor and former limit conductor; Owing to do not exert one's influence for the secondary of current transformer by the electric current of minute current conductor, divide the current conversion between the former secondary that current conductor itself do not participate in current transformer, the place adopts the method both can realize the collection of big electric current, can prevent that again current transformer from increasing volume and cost along with the increase that detects electric current, succinctly and effectively utilize the current transformer of small rated currents to realize the detection of big electric current.The primary coil number of turn is N ₁₂, the coil turn that detects the limit is N ₃₄, the resistance of former limit and vent diverter is respectively R ₁₂With R ｀ ₁₂, the electric current that the detection frontier inspection measures is I ₂, then actual current I is: I=I ₂* (1+R ₁₂/ R ｀ ₁₂) * N ₃₄/ N ₁₂

After adopting former limit to add the branch current conductor of fixed resistance value, small power electric current transformer secondary current Acquisition Circuit also will be done corresponding processing, and concrete treating method will decide according to the system that adopts the method.Can take dual mode: a kind of mode is if adopt the system of this current detecting to have software to do subsequent treatment, only need take advantage of a coefficient to get final product to the electric current that collects in software; The size of coefficient determines according to minute current conductor and former limit conductor resistance value ratio relation, as the formula (2), and with the deviation of all right correction coefficient of software processes.

Another kind of mode is that system does not have corresponding software to process, and only makes corresponding action according to the current value size cause hardware that collects.In this case, current transformer secondary current value just need the resistance value ratio relation according to minute current conductor and former limit conductor be come the corresponding amplifying circuit of doing in the amplifier hardware circuit, thereby the current value that power electronic equipment is finally obtained is identical with the real current value of system.

Be connected on two pins of the former limit of small power electric current transformer and connect copper bar or copper cash, can and connect one or more.The small power electric current transformer is welded on the PCB, adopts PCB to go up copper sheet and the use in parallel of former limit two pins.Adopt the PCB cabling simultaneously and at small power electric current transformer former limit two pins and connect copper bar or copper cash.

The shunting ratio of former limit of current transformer and diverter branch is more suitable below 1:10, can be cooperated by software like this and finish corresponding precision, and big again ratio also can realize, but precision be cannot say for sure to demonstrate,prove.Detectable electric current should be below 1000A better, and the accuracy of detection in this scope is than higher.

Claims (5)

1, a kind of source current pick-up unit comprises current transformer, and described current transformer comprises former limit and detects the limit, it is characterized in that described former limit is parallel with vent diverter.

2, source current pick-up unit according to claim 1 is characterized in that, described vent diverter is a resistance.

3, source current pick-up unit according to claim 2 is characterized in that, described resistance is a plurality of, and a plurality of described resistance are parallel with one another.

4, source current pick-up unit according to claim 1 is characterized in that, the proportional range of described vent diverter and described former limit shunting is less than 10:1.

5, source current pick-up unit according to claim 1 is characterized in that, described source current pick-up unit also comprises the computing module of calculating actual current according to detected galvanometer, and the primary coil number of turn is N ₁₂, the coil turn that detects the limit is N ₃₄, the resistance of former limit and vent diverter is respectively R ₁₂And R` <sub>12</sub>, the electric current that the detection frontier inspection measures is I <sub>2</sub>, then actual current I is: I=I <sub>2</sub>* (1+R <sub>12</sub>/ R` ₁₂) * N ₃₄/ N ₁₂

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