CN101930492B - Analytical model for saturable reactor for converter valve - Google Patents

Abstract

The invention provides an analytical model for a saturable reactor for a converter valve. The saturable reactor for the converter valve consists of a coil and an iron core; and the working state of the iron core has a linear stage and a nonlinear stage under rated operation. In order to better perform electrical design and electrical analysis on the saturable reactor, the invention provides an analytical model for the saturable reactor for the converter valve. The analytical model comprises a coil resistance, a coil inductance, a core inductance, a core resistance, a terminal capacitance and other parameters. Corresponding electrical parameters of saturable reactors with different shapes and dimensions can be calculated. The analytical model has the advantages of clear physical conception, and capacities of easily acquiring each parameter needed in the model through a real object and providing a foundation for deep analysis of the saturable reactor.

Description

A kind of analytic model of saturable reactor for converter valve

Technical field

The present invention relates to the electric system devices field, relate in particular to a kind of analytic model of saturable reactor for converter valve.

Background technology

The direct-current transmission converter valve saturable reactor is one of vitals of protection thyristor in converter valve.It is comprised of unshakable in one's determination and winding, utilizes the saturated characteristics of the saturation characteristic acquisition electric parameter of material unshakable in one's determination.Because the nonlinear characteristic of saturable reactor is relevant with material unshakable in one's determination, and that the thyristor in You Yuqi place, working point converter valve unshakable in one's determination is opened is current related, so the prerequisite that its electrical design and electrical specification are analyzed all must be according to the rational electrical model of saturable reactor.

The structure of existing saturable reactor mainly is divided into two classes, simplex winding and double winding.Electrical model for simplex winding structure and double-winding structure has document to mention, but not comprehensive.What have does not consider the non-linear of iron-core inductance, and what have does not consider the non-linear of iron loss resistance, and what have does not consider electric capacity between end, even the non-linear two sections line segments etc. that also it are approximately of considering iron-core inductance that have.

Document (Barnes, M.J.The prediction and control of transients in thyristor valves, PhD thesis, University of Aston in Birmingham, May 1985) analyzed the earliest the model of saturable reactor, considered non-linear characteristics of inductance, but be considered as steady state value for the equivalent resistance of its iron loss characteristic, the actual conditions of this and saturable reactor differ far away.The present invention has considered the comprehensive nonlinear model of saturable reactor, and provides the analytic model of its nonlinear inductance and non-linear iron loss resistance, from the analyticity of the comprehensive and nonlinear characteristic of reactor model aspect all than existing document more comprehensively.

Summary of the invention

The object of the invention is to, a kind of analytic model of saturable reactor for converter valve is provided.Saturable reactor for converter valve consists of coil and iron core, and under specified operation, duty unshakable in one's determination covers linear and non-linear two stages.In order to carry out better electrical design and the electrical analysis of saturable reactor, the invention provides a kind of analytic model of saturable reactor for converter valve.Analytic model comprises between coil resistance, coil inductance, iron-core inductance, resistance unshakable in one's determination, end the parameters such as electric capacity.The saturable reactor of different physical dimension can calculate its corresponding electric parameter.This analytic model physical concept is clear, by material object, can be easy to obtain needed each parameter in model, for analysis foundation has been established in the in-depth analysis of saturable reactor.

The analytic model of a kind of saturable reactor for converter valve of the present invention comprises:

(1) coil resistance of saturable reactor, its concrete value and reactor winding sectional area, resistivity of material are relevant with length;

(2) equivalent capacity between the end of saturable reactor, between sign saturable reactor coil, between electric capacity, coil and iron core, between electric capacity, iron core, capacitor equivalent is to the capacitance between end, and concrete value is relevant to reactor;

(3) air core inductor of saturable reactor, the natural inductance of sign saturable reactor coiler part, concrete value is relevant to the structure of reactor winding;

(4) the non-linear iron-core inductance of saturable reactor, characterize the nonlinear inductance that saturable reactor nonlinear magnetization characteristics effect unshakable in one's determination embodies, variable is the electric current flow through on nonlinear inductance, when electric current is less than certain threshold value, described threshold value is the 100-900 ampere, nonlinear inductance is steady state value, specifically depends on reactor winding and structure unshakable in one's determination, linear magnetic permeability unshakable in one's determination etc.; Electric current is during higher than threshold, and nonlinear inductance is decayed with exponential form, and the index value depends on the saturation characteristic of core material and the structure of saturable reactor;

(5) non-linear resistance of saturable reactor, characterize the effect of saturable reactor core loss characteristic, and the loss of the power analog representation saturable reactor iron core consumed on this resistance, comprise eddy current loss, magnetic hysteresis loss etc.The variable of the non-linear resistance of saturable reactor is the electric current that flows through nonlinear inductance, when electric current is less than certain threshold value,, non-linear resistance is steady state value, described threshold value is the 100-900 ampere; Electric current is during higher than threshold, and non-linear resistance is decayed with exponential form, and the index value depends on the saturation characteristic of core material and the structure of saturable reactor;

(6) annexation of analytic model is: the nonlinear inductance of saturable reactor and non-linear resistance are relation in parallel, then with air core inductor and the resistance of saturable reactor, connect, Capacitance parallel connection between the end of final and saturable reactor.

Wherein, establish R _DcFor the coil resistance of saturable reactor, C _oFor equivalent capacity between the saturable reactor end, L _oFor the air core inductor of saturable reactor, non-linear iron-core inductance parameter L _mWith non-linear iron loss resistance parameter R _mBe calculated as:

$L_m=\left\{\begin{array}{cc}{L}_d& I_m<I_{\mathrm{oL}}\\ L_d{\left(\frac{I_{\mathrm{oL}}}{I_m}\right)}^{{\mathrm{\&alpha;}}_L}& I_m\&GreaterEqual;I_{\mathrm{oL}}\end{array}\right.,R_m=\left\{\begin{array}{cc}{R}_e& I_m<I_{\mathrm{oR}}\\ R_e{\left(\frac{I_{\mathrm{oR}}}{I_m}\right)}^{{\mathrm{\&alpha;}}_R}& I_m\&GreaterEqual;I_{\mathrm{oR}}\end{array}\right.$

I _mFlow through the electric current of saturable reactor when not considering demagnetizing effect unshakable in one's determination; L _dFor the unsaturated value of saturable reactor nonlinear inductance, I _OLFor the exciting current threshold value of saturable reactor inductance nonlinear characteristic, described threshold value is the 100-900 ampere, α _LSpeed for the decay of saturable reactor nonlinear inductance; R _eFor the unsaturated value of the non-linear iron loss resistance of saturable reactor, I _ORFor the exciting current threshold value of saturable reactor iron loss non-linear resistance, described threshold value is the 100-900 ampere, α _RSpeed for the decay of saturable reactor nonlinear inductance.

The coil resistance R of saturable reactor _DcCan pass through the resistance calculations formula

Calculate, wherein ρ is the resistivity of coil, and l is the length of winding wire, and s is the net sectional area of winding wire;

Between the saturable reactor end, equivalent capacity is the stray capacitance between stray capacitance, iron-cored cake and the iron-cored cake combined between coil and iron core, the equivalent stray capacitance that the stray capacitance between coil turn is seen into from the saturable reactor coil port afterwards; Can estimate C by analytic formula _o=ε s ₁/ d ₁, wherein ε is the effective dielectric constant by coil, iron core, air, insulating medium structures shape, s ₁For the conductive area of saturable reactor coil outlet row, d ₁For the distance between the saturable reactor outlet row, accurate computing method can calculate by the method for Numerical Calculation of Electromagnetic Field:

$L=\frac{\mathrm{d\&psi;}}{\mathrm{di}}=\frac{d\left({\mathrm{\&psi;}}_o\right)}{\mathrm{di}}+\frac{d\left({\mathrm{\&psi;}}_m\right)}{\mathrm{di}}=L_o+L_m$

Wherein, L is the inductance of saturable reactor.ψ be saturable reactor galvanization coil that produce with magnetic linkage self coil interlinkage, comprising two parts: ψ _oThat for the galvanization coil, produce in a vacuum and magnetic linkage self coil interlinkage, ψ _mThat for the galvanization coil, produce in iron core and magnetic linkage self coil interlinkage; Corresponding saturable reactor inductance L also is divided into two parts, is respectively L _oAnd L _m

L _oFor the air core inductor of saturable reactor, to be in the degree of depth saturated for the iron core in the saturable reactor structure, when namely magnetic permeability unshakable in one's determination is the magnetic permeability of air, and the inductance value of saturable reactor, wherein corresponding I _m=0, therefore L=L _oThis inductance value equals the iron core saturable reactor is removed from numerical value, the inductance value of corresponding air core coil; Therefore L _oThe air core inductor that is called saturable reactor;

L _mFor the iron-core inductance of saturable reactor, characterize in the saturable reactor structure and exist unshakable in one's determinationly, be also that magnetic permeability is while being greater than air permeability, due to the corresponding inductance value of magnetic linkage of iron core contribution; L _mNon-linear characteristics of inductance be because the non-linear of core material in saturable reactor causes; When core material is operated in the range of linearity, between interior magnetic linkage unshakable in one's determination and exciting current, be linear relationship, therefore corresponding iron-core inductance value is L in this case _d

I _mWhen not considering demagnetizing effect unshakable in one's determination, flow through the electric current of saturable reactor winding, i.e. current flowing I in the saturable reactor winding _mThe time, in the situation that ignore demagnetizing effect unshakable in one's determination, so now the inductance value of saturable reactor is L=L _o+ L _m, I _OLFor the electric current threshold value, described threshold value is the 100-900 ampere, and its size is determined by the saturation point of concrete core material:

$B_s\mathrm{lB}{\mathrm{\&mu;}}_0{\mathrm{NI}}_{\mathrm{oL}}\&DoubleRightArrow;I_{\mathrm{oL}}B\frac{B_{s}l}{{\mathrm{\&mu;}}_{0}N}$

B wherein _sFor the saturation magnetic induction of saturable reactor iron core, be the intrinsic parameter of nonlinear material unshakable in one's determination; μ ₀For the magnetic permeability of vacuum, it is a constant; N is the number of turn of saturable reactor coil, and l is the central circumference of saturable reactor iron-cored cake.Work as I _mBe less than I _OLDuring this threshold value, described threshold value is the 100-900 ampere, and iron core is operated in the range of linearity, and now the inductance value of saturable reactor is L=L _o+ L _d, i.e. iron-core inductance L _m=L _dWork as I _mBe greater than I _OLThe time, iron core is operated in nonlinear area, along with electric current I _mProgressively increase, working point unshakable in one's determination also progressively moves towards saturated, corresponding iron-core inductance is also reducing gradually; The definition iron-core inductance is along with the speed speed α of current reduction _LDescribe, and iron-core inductance is also to be decided by the core material characteristic that the saturation reactance implement body is selected along with the speed speed of current reduction;

R _mFor characterizing the equivalent resistance of iron loss unshakable in one's determination, iron loss comprises eddy current loss, magnetic hysteresis loss and different name loss, and its variable is demarcated too as I _m, be the flex point I of iron loss resistance corresponding current _ORFlex point I with the iron-core inductance corresponding current _OLDifference, this is also that characteristic by selected core material is determined, in addition, iron loss electrical resistance electric current I _mThe speed speed α that increases and reduce _RMean, this variation tendency and iron-core inductance are with I _mThe variation tendency difference, by the core material characteristic of specifically selecting, realized.

The invention has the beneficial effects as follows:

1. the clear physics conception of analytic model;

2. the expression formula of analytic model is clear;

3. analytic model parameter and physical dimension transform simple and convenient;

4. the electric parameter of analytic model is comprehensive.

The accompanying drawing explanation

Fig. 1 shows the electrical model structural representation of saturable reactor of the present invention.

Fig. 2 shows the analytic model of saturable reactor of the present invention.

Embodiment

Fig. 1 shows the electrical model structural representation of saturable reactor of the present invention.

Fig. 2 shows the analytic model of saturable reactor of the present invention.

In Fig. 1, R _DcFor the coil resistance of saturable reactor, C _oFor equivalent capacity between the saturable reactor end, L _oAir core inductor for saturable reactor.Non-linear iron-core inductance parameter L _mWith non-linear iron loss resistance R _mParameter as shown in Figure 2.

The coil resistance of saturable reactor can pass through the resistance calculations formula

Calculate, wherein ρ is the resistivity of coil, and l is the length of winding wire, and s is the net sectional area of winding wire.

Between the saturable reactor end, equivalent capacity is the stray capacitance between stray capacitance, iron-cored cake and the iron-cored cake combined between coil and iron core, the equivalent stray capacitance that the stray capacitance between coil turn is seen into from the saturable reactor coil port afterwards.Can estimate C by analytic formula _o=ε s ₁/ d ₁, wherein ε is the effective dielectric constant by coil, iron core, air, insulating medium structures shape, s ₁For the conductive area of saturable reactor coil outlet row, d ₁For the distance between the saturable reactor outlet row, accurate computing method can calculate by the method for Numerical Calculation of Electromagnetic Field.

$L=\frac{\mathrm{d\&psi;}}{\mathrm{di}}=\frac{d\left({\mathrm{\&psi;}}_o\right)}{\mathrm{di}}+\frac{d\left({\mathrm{\&psi;}}_m\right)}{\mathrm{di}}=L_o+L_m$

Wherein, L is the inductance of saturable reactor.ψ be saturable reactor galvanization coil that produce with magnetic linkage self coil interlinkage, comprising two parts: ψ _oThat for the galvanization coil, produce in a vacuum and magnetic linkage self coil interlinkage, ψ _mThat for the galvanization coil, produce in unshakable in one's determination (when magnetic permeability is greater than air permeability) and magnetic linkage self coil interlinkage.Corresponding saturable reactor inductance L also is divided into two parts, is respectively L _oAnd L _m.

L _oFor the air core inductor of saturable reactor, to be in the degree of depth saturated for the iron core in the saturable reactor structure, when namely magnetic permeability unshakable in one's determination is the magnetic permeability of air (vacuum), and the inductance value of saturable reactor (corresponding L _m=0, therefore L=L _o); This inductance value equals the iron core saturable reactor is removed from numerical value, the inductance value of corresponding air core coil.Therefore L _oThe air core inductor that is called saturable reactor.

L _mFor the iron-core inductance of saturable reactor, characterize in the saturable reactor structure while having (magnetic permeability is greater than air permeability) unshakable in one's determination, due to the corresponding inductance value of magnetic linkage of iron core contribution.L _mNon-linear characteristics of inductance be because the non-linear of core material in saturable reactor causes.When core material is operated in the range of linearity, between interior magnetic linkage unshakable in one's determination and exciting current, be linear relationship, therefore corresponding iron-core inductance value is L in this case _d.

I _mWhen not considering demagnetizing effect unshakable in one's determination (as eddy current or hysteresis effect), flow through the electric current of saturable reactor winding.Namely work as current flowing I in the saturable reactor winding _mThe time, in the situation that ignore demagnetizing effect unshakable in one's determination, so now the inductance value of saturable reactor is L=L _o+ L _m.Work as I _mBe less than I _OLDuring this threshold value (this threshold value is generally less than the hundreds of ampere) (size of this threshold value (this threshold value is generally less than the hundreds of ampere) is determined by the saturation point of concrete core material), iron core is operated in the range of linearity, and now the inductance value of saturable reactor is L=L _o+ L _d, i.e. iron-core inductance L _m=L _dWork as I _mBe greater than I _OLThe time, iron core is operated in nonlinear area, along with electric current I _mProgressively increase, working point unshakable in one's determination also progressively moves towards saturated, corresponding iron-core inductance is also reducing gradually.We define the speed speed α of iron-core inductance along with current reduction _LDescribe.And iron-core inductance is also to be decided by the core material characteristic that the saturation reactance implement body is selected along with the speed speed of current reduction.

R _mFor characterizing the equivalent resistance of iron loss unshakable in one's determination, iron loss comprises eddy current loss, magnetic hysteresis loss and different name loss.Its variable is demarcated too as I _m, be the flex point I of iron loss resistance corresponding current _ORFlex point I with the iron-core inductance corresponding current _OLDifference, this is also that characteristic by selected core material is determined.In addition, iron loss electrical resistance electric current I _mThe speed speed α that increases and reduce _RMean, this variation tendency and iron-core inductance are with I _mVariation tendency also different, these are all to be realized by the core material characteristic of specifically selecting.

The example of a reality, saturable reactor mainly are comprised of coil and iron core.There is ring-shaped core to form, internal diameter R ₁=100mm, external diameter R ₂=200mm, highly for H is 100mm, gap is 2*1%, close around winding N=32 circle above ring-shaped core, the effective conductive area s of copper conductor is 1000mm ², select the linear relative permeability μ of core material _rBe 8000, coercive force H=100A/m, saturation magnetic induction are 1.7T.The resistivity of copper conductor is p=1.851e-6 Ω m.

This example is symmetrical structure, and a lot of parameters can obtain by analytical Calculation.And, for other unsymmetric structures or ad hoc structure, all need to obtain by test method or numerical computation method as air core inductor, iron-core inductance and iron loss resistance etc.

The coil resistance of saturable reactor is:

Air core inductor L _oFor L _dFor

For electric capacity between non-linear iron loss resistance, nonlinear inductance, end, need to obtain by numerical calculations, as follows.

$L_m=\left\{\begin{array}{cc}48\mathrm{mH}& I_m<1\left(A\right)\\ 48\mathrm{mH}{\left(\frac{1}{I_m}\right)}^2& I_m\&GreaterEqual;1\left(A\right)\end{array}\right.,R_m=\left\{\begin{array}{cc}300\mathrm{\&Omega;}& I_m<0.5\left(A\right)\\ 300\mathrm{\&Omega;}{\left(\frac{0.5}{I_m}\right)}^{{\mathrm{\&alpha;}}_R}& I_m\&GreaterEqual;0.5\left(A\right)\end{array}\right.$

C _oB?300(pF)。

More than in order to make those of ordinary skills understand the present invention; and the detailed description that the present invention is carried out; but can expect; within not breaking away from the scope that claim of the present invention contains, can also make other changes and modifications, these variations and revising all in protection scope of the present invention.

Claims (2)

1. the analytic method of a saturable reactor for converter valve comprises:

(1) coil resistance of saturable reactor, its concrete value and reactor winding sectional area, resistivity of material are relevant with length;

(2) equivalent capacity between the end of saturable reactor, between sign saturable reactor coil, between electric capacity, coil and iron core, between electric capacity, iron core, capacitor equivalent is to the capacitance between end, and concrete value is relevant to reactor;

(3) air core inductor of saturable reactor, the natural inductance of sign saturable reactor coiler part, concrete value is relevant to the structure of reactor winding;

(4) the non-linear iron-core inductance of saturable reactor, characterize the nonlinear inductance that saturable reactor nonlinear magnetization characteristics effect unshakable in one's determination embodies, variable is the electric current flow through on nonlinear inductance, when electric current is less than certain threshold value, described threshold value is the 100-900 ampere, nonlinear inductance is steady state value, specifically depends on reactor winding and structure unshakable in one's determination, linear magnetic permeability unshakable in one's determination; Electric current is during higher than threshold, and nonlinear inductance is decayed with exponential form, and the index value depends on the saturation characteristic of core material and the structure of saturable reactor;

(5) non-linear resistance of saturable reactor, characterize the effect of saturable reactor core loss characteristic, and the loss of the power analog representation saturable reactor iron core consumed on this resistance, comprise eddy current loss, magnetic hysteresis loss; The variable of the non-linear resistance of saturable reactor is the electric current that flows through nonlinear inductance, and when electric current was less than certain threshold value, non-linear resistance was steady state value, and described threshold value is the 100-900 ampere; Electric current is during higher than threshold, and non-linear resistance is decayed with exponential form, and the index value depends on the saturation characteristic of core material and the structure of saturable reactor;

(6) annexation of analytic model is: the nonlinear inductance of saturable reactor and non-linear resistance are relation in parallel, then with air core inductor and the resistance of saturable reactor, connect, Capacitance parallel connection between the end of final and saturable reactor.

2. analytic method as claimed in claim 1, is characterized in that: establish R _DcFor the coil resistance of saturable reactor, C _oFor equivalent capacity between the saturable reactor end, L _oFor the air core inductor of saturable reactor, non-linear iron-core inductance parameter L _mWith non-linear iron loss resistance parameter R _mBe calculated as:

$L_m=\left\{\begin{array}{cc}{L}_d& I_m<I_{\mathrm{oL}}\\ L_d{\left(\frac{I_{\mathrm{oL}}}{I_m}\right)}^{{\mathrm{\&alpha;}}_L}& I_m\&GreaterEqual;I_{\mathrm{oL}}\end{array}\right.,$ $R_m=\left\{\begin{array}{cc}{R}_e& I_m<I_{\mathrm{oR}}\\ R_e{\left(\frac{I_{\mathrm{oR}}}{I_m}\right)}^{{\mathrm{\&alpha;}}_R}& I_m\&GreaterEqual;I_{\mathrm{oR}}\end{array}\right.$

I _mFlow through the electric current of saturable reactor when not considering demagnetizing effect unshakable in one's determination; L _dFor the unsaturated value of saturable reactor nonlinear inductance, I _OLFor the exciting current threshold value of saturable reactor inductance nonlinear characteristic, described threshold value is the 100-900 ampere, α _LSpeed for the decay of saturable reactor nonlinear inductance; R _eFor the unsaturated value of the non-linear iron loss resistance of saturable reactor, I _ORFor the exciting current threshold value of saturable reactor iron loss non-linear resistance, described threshold value is the 100-900 ampere, α _RSpeed for the decay of saturable reactor nonlinear inductance;

The coil resistance R of saturable reactor _DcBy the resistance calculations formula Calculate, wherein ρ is the resistivity of coil, and l is the length of winding wire, and s is the net sectional area of winding wire;

Between the saturable reactor end, equivalent capacity is the stray capacitance between stray capacitance, iron-cored cake and the iron-cored cake combined between coil and iron core, the equivalent stray capacitance that the stray capacitance between coil turn is seen into from the saturable reactor coil port afterwards; By analytic formula, estimate C _o=ε s ₁/ d ₁, wherein ε is the effective dielectric constant by coil, iron core, air, insulating medium structures shape, s ₁For the conductive area of saturable reactor coil outlet row, d ₁For the distance between the saturable reactor outlet row, accurate computing method calculate by the method for Numerical Calculation of Electromagnetic Field:

$L=\frac{\mathrm{d\&psi;}}{\mathrm{di}}=\frac{d\left({\mathrm{\&psi;}}_o\right)}{\mathrm{di}}+\frac{d\left({\mathrm{\&psi;}}_m\right)}{\mathrm{di}}=L_o+L_m$

Wherein, L is the inductance of saturable reactor; ψ be saturable reactor galvanization coil that produce with magnetic linkage self coil interlinkage, comprising two parts: ψ _oThat for the galvanization coil, produce in a vacuum and magnetic linkage self coil interlinkage, ψ _mThat for the galvanization coil, produce in iron core and magnetic linkage self coil interlinkage; Corresponding saturable reactor inductance L also is divided into two parts, is respectively L _oAnd L _m

L _oFor the air core inductor of saturable reactor, to be in the degree of depth saturated for the iron core in the saturable reactor structure, when namely magnetic permeability unshakable in one's determination is the magnetic permeability of air, and the inductance value of saturable reactor, wherein corresponding L _m=0, therefore L=L _oThis inductance value equals the iron core saturable reactor is removed from numerical value, the inductance value of corresponding air core coil; Therefore L _oThe air core inductor that is called saturable reactor;

L _mFor non-linear iron-core inductance parameter, characterize in the saturable reactor structure and exist unshakable in one's determinationly, be also that magnetic permeability is while being greater than air permeability, due to the corresponding inductance value of magnetic linkage of iron core contribution; L _mNon-linear characteristics of inductance be because the non-linear of core material in saturable reactor causes; When core material is operated in the range of linearity, between interior magnetic linkage unshakable in one's determination and exciting current, be linear relationship, therefore corresponding iron-core inductance value is L in this case _d

I _mWhen not considering demagnetizing effect unshakable in one's determination, flow through the electric current of saturable reactor winding, i.e. current flowing I in the saturable reactor winding _mThe time, in the situation that ignore demagnetizing effect unshakable in one's determination, so now the inductance value of saturable reactor is L=L _o+ L _m, I _OLFor the electric current threshold value, described threshold value is the 100-900 ampere, and its size is determined by the saturation point of concrete core material:

$B_{s}l\stackrel{\&CenterDot;}{=}{\mathrm{\&mu;}}_0{\mathrm{NI}}_{\mathrm{oL}}\&DoubleRightArrow;I_{\mathrm{oL}}\stackrel{\&CenterDot;}{=}\frac{B_{s}l}{{\mathrm{\&mu;}}_{0}N}$

B wherein _sFor the saturation magnetic induction of saturable reactor iron core, be the intrinsic parameter of nonlinear material unshakable in one's determination; μ ₀For the magnetic permeability of vacuum, it is a constant; N is the number of turn of saturable reactor coil, and 1 is the central circumference of saturable reactor iron-cored cake; Work as I _mBe less than I _OLDuring this threshold value, described threshold value is the 100-900 ampere, and iron core is operated in the range of linearity, and now the inductance value of saturable reactor is L=L _o+ L _d, i.e. iron-core inductance L _m=L _dWork as I _mBe greater than I _OLThe time, iron core is operated in nonlinear area, along with electric current I _mProgressively increase, working point unshakable in one's determination also progressively moves towards saturated, corresponding iron-core inductance is also reducing gradually; The definition iron-core inductance is along with the speed speed α of current reduction _LDescribe, and iron-core inductance is also to be decided by the core material characteristic that the saturation reactance implement body is selected along with the speed speed of current reduction;

R _mFor characterizing the equivalent resistance of iron loss unshakable in one's determination, iron loss comprises eddy current loss, magnetic hysteresis loss and different name loss, and its variable is demarcated too as I _m, be the flex point I of iron loss resistance corresponding current _ORFlex point I with the iron-core inductance corresponding current _OLDifference, this is also that characteristic by selected core material is determined, in addition, iron loss electrical resistance electric current I _mThe speed speed α that increases and reduce _RMean, this variation tendency and iron-core inductance are with I _mThe variation tendency difference, by the core material characteristic of specifically selecting, realized.

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