CN2256154Y - High speed electronic mutual inductor with power supply - Google Patents

Abstract

The utility model relates to a high speed electronic mutual inductor with a power source. The utility model is composed of an iron core magnetic ring, a primary coil, a secondary coil also used as compensation, an externally connected voltage source, a magnetoelectric sensor, an amplifying circuit and a measuring circuit. The utility model has the characteristics of high measuring precision and high response speed, and has wide application prospects in electronic equipment and devices of high frequency and needing fast response.

Description

Active high-velocity electrons instrument transformer

The utility model relates to a kind of electronic instrument of special measurement ac electric, is widely used for measuring any numerical value of ac parameter (electric current, voltage, power and electric energy etc.) in electric power system and electronic measurements circuit.

At present, the known instrument transformer that is used to measure ac electric is the passive device of making according to transformer principle.With the instrument transformer of measuring electric current is example, and it is not-time to omit error, and with reference to the current transformer structure electrical schematic diagram of Fig. 3, the most basic computing formula of current transformer is:

I ₁N ₁=I ₂N ₂(1) wherein: I ₁And N ₁Be respectively the electric current and the number of turn of primary coil; I ₂And N ₂Be respectively the electric current and the number of turn of secondary coil.From being series at secondary coil N ₂In the secondary current I that records of ammeter A ' ₂And formula (1) can be tried to achieve measured electric current I ₁In the actual current instrument transformer, need exciting curent I ₀Supply with excitatory and power consumption unshakable in one's determination, excitatory ampere-turn I ₀N ₁Just caused the error of current transformer.According to theory analysis, the current measurement errors and the phase angle error of current transformer are respectively: $f_I=[C-\frac{I_0\mathrm{COS}({\mathrm{\&phi;}}_0-{\mathrm{\&psi;}}_2)}{K_I{I}_2}]---\left(2\right)$ ${\mathrm{\&delta;}}_I=\frac{I_0{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="Y9520395200091.png"\; state="\{\{state\}\}">N</figure-callout>}}_1\mathrm{SIN}({\mathrm{\&phi;}}_0-{\mathrm{\&psi;}}_2)}{I_2{N}_2}---\left(3\right)$ Wherein: $C=1-\frac{N_2}{N_1{K}_I}---\left(4\right)$ F in the formula _IBe current error, δ _IBe phase angle error, C is a constant, I ₀Be magnetizing current, N ₁And N ₂Be respectively the number of turn of former limit and secondary coil, K _IBeing the specified coefficient of mutual inductance of electric current, is the primary current rated value and the ratio of secondary current rated value, I ₂Be secondary current, ₀Be I ₀And the angle between its real component, Ψ ₂Be I ₂With its angle of electromotive force.By formula (2) as can be seen, the principal element that causes measure error is magnetizing current I ₀With reference to Fig. 4, can see that the tested electric current of experiment measuring does not overlap at the current waveform of 2 of the A, the B that import and export instrument transformer.Frequency is high more, and difference is big more, and electric current is big more, and difference is also big more, and response speed is also slow more.A kind of certainty of measurement height is arranged at present, and the current sensor that the fast employing hall device of response speed is made is used to AC measurment increasingly extensively.But its temperature coefficient is bigger than common instrument transformer, little (as the 1A) alternating current of neither suitable measurement.

The purpose of this utility model provides the electronic installation of a more perfect measurement ac electric.Make that it has the certainty of measurement height, response speed is fast, temperature coefficient is little, high frequency characteristics is good, and it is wide to measure current range, both can have surveyed the training of several Wan An, can survey little active electronic instrument transformer again to 1 Ampere currents.

The utility model is achieved in that resistance and the voltmeter that is wound with primary coil (or claiming primary coil) and secondary coil (or claiming secondary coil) and is used to measure secondary current on a magnet ring unshakable in one's determination.It is characterized in that secondary winding promptly is a bucking coil, secondary current just offset current is provided by external power supply fully.In addition, the magnetoelectric transducer that installs additional in the magnetic circuit of magnet ring is as the nulling element in magnetic field.The output signal of magnetoelectric transducer is amplified through operational amplifier and power amplifier, the output termination bucking coil of power amplifier, whole measuring system is in dynamic equilibrium state, when the ampere-turn of elementary winding increases, the also corresponding increase of the ampere-turn of bucking coil, elementary ampere-turn reduces, and compensation ampereturns also reduces thereupon.The magnitude of field intensity that both produce in magnet ring equates that direction is opposite, thereby can make the electric current of the magnetization magnet ring that exists in the common current instrument transformer be reduced to zero.

Owing to adopt such scheme, the electric current of magnetization magnet ring is reduced to zero, and this has just fundamentally improved certainty of measurement and response speed.The utility model the use in ac electric quantity measuring, especially has the better application prospect in the electronic measurement circuit that the requirement of high-frequency circuit and response speed is very fast and required precision is very high except that alternative known current transformer and current sensor.

The utility model is an embodiment accompanying drawings specific embodiments with the active electronic instrument transformer of measuring alternating current.

Fig. 1 is active high speed current transformer circuit block diagram.

Fig. 2 is active high speed current transformer circuit figure.

Fig. 3 is a common current instrument transformer electrical schematic diagram.

Fig. 4 is that the primary current of common current instrument transformer is imported the current waveform figure that limit A point and output limit B are ordered.

Fig. 5 is that the primary current of active high speed current transformer is imported the current waveform figure that limit A point and output limit B are ordered.

Table 1 is active high speed current transformer and common current instrument transformer and current sensor characteristic comparison sheet.

Specifically described below in conjunction with the active high speed current transformer of accompanying drawing one of embodiment of the active high-velocity electrons instrument transformer of the utility model.

With reference to accompanying drawing 1, active high speed current transformer comprises magnetic circuit system 1, operational amplification circuit 2, power amplification circuit 3, power supply 4 and measuring circuit 5.With reference to accompanying drawing 2, in magnetic circuit system 1, except that comprising magnet ring, the primary coil N that common instrument transformer has ₁With promptly be that secondary coil is again bucking coil N _sComprise that also a magnetoelectric transducer is as the nulling element outward.Also comprise external power supply, operational amplifier and power amplification circuit that common instrument transformer does not all have.This active high speed current transformer is to connect like this, and the magnetoelectric transducer P in the magnetic circuit 1 has two terminals, and they receive amplifier A by the resistance R of two equal resistances ₁Two inputs, signal is through A ₁Amplify the back from A ₁Output receive two transistor Ts in the power amplifier 2 ₁And T ₂Base stage, two base stages are and connect.T ₁And T ₂Emitter and connect after link bucking coil N in the magnetic circuit system 1 _sAn end points, N _sThe other end and the circuit 5 of measuring electric current in resistance R ₀Link to each other with voltmeter V ' and contact.Resistance R ₀With voltmeter V ' another and contact ground connection.Transistor T ₁Collector electrode connect power supply 4+15V, transistor T ₂Collector electrode connect in the power supply 4-15V, active high-velocity electrons instrument transformer+15V and-the 15V power supply by 220 volts alternating currents through after overvoltage is adjusted integrated circuit 7815 and 7915 adjustings, obtaining respectively again behind transformer T step-down, full-wave rectification, the capacitor filtering.

Active high speed current transformer is work like this, works as measured current I ₁Flow through former limit winding N ₁When passing magnet ring M, the signal of magnetoelectric transducer P perception is delivered to amplifier A ₁Amplify, further amplify offset current I of back output through power amplification circuit 3 again _sFeed back to bucking coil N _sIn, to primary current I ₁The magnetic field that produces in magnet ring compensates.As primary current I ₁The magnetic field and the offset current I that produce _sDuring the magnetic field opposite sign but equal magnitude that produces, then magnet ring magnetic field is zero.Can get according to transformer principle:

I ₁N ₁=I _sN _s(5) can get I by (5) formula ₁: ${\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="Y9520395200091.png"\; state="\{\{state\}\}">I</figure-callout>}}_1=\frac{I_s{N}_s}{N_1}---\left(6\right)$ N in the following formula (6) _s, N ₁For known, and I _sCan measure I by voltmeter V _sAt standard resistor R ₀On voltage drop V _R0Obtain, that is:

I _s=V _R0/ R ₀(7) have in conjunction with (6) and (7) formula: ${\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="Y9520395200091.png"\; state="\{\{state\}\}">I</figure-callout>}}_1=\frac{N_s{V}_{R0}}{N_1{R}_0}---\left(8\right)$ This active high speed current transformer is to keep dynamic equilibrium, measured current I like this ₁Be time dependent, as primary current I ₁When becoming big, the signal of magnetoelectric transducer P institute perception increases thereupon, after discharge circuit 2 and power amplifier 3 amplifies with big I _sTo primary current I ₁The magnetic field that produces compensates.Otherwise, work as I ₁When reducing, I _sAlso reduce thereupon, make magnetic field still keep dynamic equilibrium state.Thereby eliminated common instrument transformer because the measure error that primary current is caused magnet ring magnetization acting.

With reference to the empirical curve of Fig. 5, demonstrate the superiority of this utility model clearly.The current waveform that 2 of A, B were imported, exported to the electric current of active high speed current transformer overlaps substantially.It is measured current I ₁Its size and phase place remain unchanged in measuring process.With reference to the empirical curve among Fig. 4, when utilizing common instrument transformer to measure electric current, tested electric current is that primary current does not overlap at 2 current waveforms of A, the B of input and output instrument transformer, demonstrates tangible phase difference, and variation has taken place promptly tested electric current phase place of itself in measuring process.This can cause measure error naturally.Its reason is that tested current magnetization magnet ring causes, because the utility model utilizes the energy of external power supply to measured current I ₁The acting of magnetization magnet ring compensates.It is more superior than the performance of common instrument transformer and current sensor clearly to demonstrate the utility model with reference to table I.It has the certainty of measurement height, and response speed is fast, the characteristics that temperature coefficient is little.Its temperature coefficient is than the little order of magnitude of current sensor.Frequency characteristic is good, and operating frequency is the highest in the three, can measure the alternating current of 500KHZ.It not only can be surveyed big electric current but also guarantee high certainty of measurement too when surveying little electric current.The utility model has wide practical use in the high-frequency high-speed electronic measurements.Table 1 instrument transformer, current sensor and high-velocity electrons instrument transformer are relatively

Performance	Instrument transformer	Current sensor	The high-velocity electrons instrument transformer
				Response speed	Slowly	Hurry up	Very fast
Certainty of measurement	Generally	High	High
				Survey little current capacity (precision)	Difference	Difference	Good
Response speed when surveying little electric current	Difference	Difference	Good
				Temperature coefficient	Good	Difference	Good
Noise	Low	High	Low
				The loop is influenced	Greatly	What have is big	Do not have
Measuring range	Narrow	Wide	Very wide
				Material uses	Take	Economize	Economize
Reliability	High	High	High
				Frequency range	20- 400HZ	0- 100KHZ	20～ 500KHZ
Consistency	Good	Generally	Good
				Volume	Greatly	Little	Little
Price	Low	High	Low

Claims (1)

1. active high-velocity electrons instrument transformer, it comprises the primary coil N that is around on the magnet ring M ₁Secondary coil N with the double as bucking coil _s, it is characterized in that bucking coil N _sAn end use standard resistor R with measuring ₀Link to each other transistor T in the other end and the power amplification circuit with one of voltmeter V ' and contact ₁And T ₂Two emitter tie points link to each other, two outputs of magnetoelectric transducer P that place magnetic circuit are by two resistance R and operational amplifier A that resistance is identical ₁Input link to each other operational amplifier A ₁Output and power amplification circuit in transistor T ₁And T ₂Base stage and contact link to each other transistor T ₁And T ₂Collector electrode connect respectively power supply+15V and-15V.

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