MAGNETIC-INDUCTANCE COMPONENT

Abstract

The present invention provides a magnetic-inductance component, and relates to the field of magnetic circuit theory and application, and in particular, to the design of magnetic circuit components. The magnetic-inductance component is a multi-turn short-circuit coil wound around a magnetic circuit. A magnetic-inductance value of the magnetic-inductance component is adjusted by selecting metal conductors with different numbers of turns, materials, cross-sectional areas, and lengths to change an amplitude and a phase of a magnetic flux of the magnetic circuit. The present invention purposely changes the operating state and operating trajectory of a vector in the magnetic circuit by adding the magnetic-inductance component to the magnetic circuit or removing the magnetic-inductance component from the magnetic circuit, to make a state of a magnetic flux vector in the magnetic circuit to be consistent with a target magnetic flux vector state. Compared with a magnetic circuit including a reluctance only, a magnetic circuit vector model built by using the magnetic-inductance component as a core is more consistent with the actual physical situation, which is beneficial to the improvement of the accuracy of magnetic circuit analysis and calculation.

Claims

1. A magnetic-inductance component, wherein the magnetic-inductance component is a multi-turn short-circuit coil wound around a magnetic circuit; and a magnetic-inductance value of the magnetic-inductance component is adjusted by selecting metal conductors with different numbers of turns, materials, cross-sectional areas, and lengths to change an amplitude and a phase of a magnetic flux of the magnetic circuit, or a state of a magnetic flux vector in the magnetic circuit is made consistent with a target magnetic flux vector state by adding the magnetic-inductance component to the magnetic circuit or removing the magnetic-inductance component from the magnetic circuit.

2. The magnetic-inductance component according to claim 1, wherein a coefficient L.sub.mc of the magnetic-inductance value of the magnetic-inductance component is related to the number of turns N.sub.r of the short-circuit coil and a resistance R.sub.r of the short-circuit coil, that is, $L_{mc}=\frac{N_r}{R_r},$ wherein magnetic-inductance is measured in Ω.sup.−1; and when n magnetic-inductance components are connected in series, an expression for an equivalent magnetic-inductance value is L.sub.mceq=L.sub.mc1+L.sub.mc2+ . . . +L.sub.mcn−1+L.sub.mcn, or when n magnetic-inductance components are connected in parallel, an expression for an equivalent magnetic-inductance value is $L_{mceq}=1/\left(\frac{1}{L_{mc1}}+\frac{1}{L_{mc2}}+.Math.\frac{1}{L_{mcn-1}}+\frac{1}{L_{mcn}}\right).$

3. The magnetic-inductance component according to claim 1, wherein the magnetic-inductance component has an obstructive effect on an alternating magnetic flux, but has no obstructive effect on a constant magnetic flux, an expression for a magnetic reactance is defined as X.sub.mc=ωL.sub.mc, to describe the degree of the obstructive effect of the magnetic-inductance component on the alternating magnetic flux, wherein ω is an angular frequency of the magnetic flux varied in the magnetic circuit.

4. The magnetic-inductance component according to claim 3, wherein a magnetic impedance value in the magnetic circuit is Z.sub.mc=√{square root over (R.sub.mc.sup.2+X.sub.mc)}, and a magnetic impedance angle in the magnetic circuit is φ.sub.mc=arctan(X.sub.mc/R.sub.mc), wherein R.sub.mc is a reluctance value of the magnetic circuit.

5. The magnetic-inductance component according to claim 1, wherein the Ohm's law of the magnetic circuit is used to verify whether a set magnetic-inductance value is consistent with a theoretical value; and an Ohm's law expression for the magnetic circuit is {dot over (F)}=(R.sub.mc+jωL.sub.mc){dot over (Φ)}, wherein j represents an imaginary unit, R.sub.mc is a reluctance value of the magnetic circuit, is an angular frequency of the magnetic flux varied in the magnetic circuit, L.sub.mc represents the magnetic-inductance value of the magnetic-inductance component, {dot over (Φ)} represents the magnetic flux vector in the magnetic circuit, and {dot over (F)} represents a magnetomotive force (MMF) vector in the magnetic circuit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a schematic diagram showing a plurality of magnetic-inductance components connected in series according to the present invention.

[0016] FIG. 2 is a schematic diagram showing a plurality of magnetic-inductance components connected in parallel according to the present invention.

[0017] FIG. 3 is a flowchart of changing the operating state of a magnetic circuit by a magnetic-inductance component according to the present invention.

[0018] FIG. 4 is a waveform diagram of an initial excitation current and an initial magnetic flux of a transformer according to the present invention.

[0019] FIG. 5 is an equivalent magnetic circuit diagram of a transformer to which a magnetic-inductance component is added according to the present invention.

[0020] FIG. 6 is a waveform diagram of an excitation current and a magnetic flux of a transformer to which a magnetic-inductance component is added according to the present invention.

DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be further described below in detail with reference to the accompanying drawings.

[0022] The present invention provides a magnetic-inductance component. The basic idea of the present invention is to purposely change the operating state and operating trajectory of vectors in a magnetic circuit by adding the magnetic-inductance component to the magnetic circuit or removing the magnetic-inductance component from the magnetic circuit. For example, when the MMF force in the magnetic circuit is stable, the magnetic-inductance component is added to the magnetic circuit to change the magnitude of the magnetic flux in the magnetic circuit and the phase angle between the MMF and the magnetic flux, to make the state of the magnetic flux vector in the magnetic circuit consistent with a target magnetic flux vector state.

[0023] The magnetic-inductance component physically takes the form of a multi-turn short-circuit coil wound around the magnetic circuit, and is expressed as L.sub.mc, where the subscript “mc” is the abbreviation of magnetic circuit. Corresponding to an inductance component in an electric circuit, a magnetic-inductance L.sub.mc has an obstructive effect on an alternating magnetic flux, but has no obstructive effect on a constant magnetic flux.

[0024] Further, a calculation formula for the magnetic-inductance is

[00003]$L_{mc}=\frac{N_r^2}{R_r},$

where R.sub.r is a resistance of the short-circuit coil, and the magnetic-inductance is measured in Ω.sup.−1. This formula corresponds to the relationship between the electrical inductance and the reluctance in the electric circuit, that is,

[00004]$L=\frac{N_L^2}{R_{mc}},$

where R.sub.mc is a reluctance value of the magnetic circuit. The magnitude of a magnetic-inductance value is related to the number of turns of the short-circuit coil and the resistance of the short-circuit coil. The magnetic-inductance value of the magnetic-inductance component can be adjusted by selecting metal conductors with different numbers of turns, materials, cross-sectional areas, and lengths. When the frequency of the magnetic flux in the magnetic circuit is high, the resistance value of the magnetic-inductance component changes due to the skin effect. In this case, an AC resistance value should be used to calculate the magnetic-inductance value.

[0025] Further, corresponding to the inductance component in the electric circuit, when n magnetic-inductance components are connected in series, as shown in FIG. 1, an expression for an equivalent magnetic-inductance value is L.sub.mceq=L.sub.mc1+L.sub.mc2+ . . . +L.sub.mcn−1+L.sub.mcn; or when n magnetic-inductance components are connected in parallel, as shown in FIG. 2, an expression for an equivalent magnetic-inductance value is

[00005]$L_{mceq}=1/\left(\frac{1}{L_{mc1}}+\frac{1}{L_{mc2}}+.Math.\frac{1}{L_{mcn-1}}+\frac{1}{L_{mcn}}\right).$

[0026] Further, in order to describe the degree of the obstructive effect of the magnetic-inductance component on the alternating magnetic flux, an expression for a magnetic reactance is defined as X.sub.mc=ωL.sub.mc, where ω is an angular frequency of the magnetic flux varied in the magnetic circuit.

[0027] Further, an expression for the reluctance in the magnetic circuit is defined as

[00006]$R_{\mathrm{mc}}=\frac{l_m}{{\mu }_m{s}_m},$

where l.sub.m is an equivalent length that the magnetic flux flows around the magnetic circuit, s.sub.m is an equivalent cross-sectional area that the magnetic flux flows around the magnetic circuit, and μ.sub.m is a magnetic permeability of the material of the magnetic circuit. The reluctance represents a constant obstructive effect of the magnetic circuit on the magnetic flux, which obstructs both the alternating magnetic flux and the constant magnetic flux. In a magnetic circuit including no magnetic-inductance component, when the MMF is constant, the reluctance can change the magnitude of the magnetic flux, but does not change the phase of the magnetic flux.

[0028] Further, corresponding to the definition of impedance in the electric circuit, the reluctance and the magnetic reactance constitute a magnetic impedance. A magnetic impedance value in the magnetic circuit can be calculated by using Z.sub.mc=√{square root over (R.sub.mc.sup.2+X.sub.mc.sup.2)}, and a magnetic impedance angle in the magnetic circuit can be calculated by using φ.sub.mc=arctan(X.sub.mc/R.sub.mc). The magnetic reactance and the reluctance can be respectively calculated by using a formula X.sub.mc=Z.sub.mcsinφ.sub.mc and a formula R.sub.mc=Z.sub.mccosφ.sub.mc.

[0029] Further, a magnetic circuit topology composed of four magnetic circuit components including an MMF, a magnetic flux, a reluctance, and a magnetic-inductance satisfies the Ohm's law of the magnetic circuit, that is, {dot over (F)}=(R.sub.mc+jωL.sub.mc){dot over (Φ)}.

[0030] In the present invention, a process of changing the state of the magnetic circuit by adding the magnetic-inductance component is as follows:

[0031] An amplitude (effective value) of the magnetic flux in the magnetic circuit is set to constant ∥{dot over (Φ)}.sub.181 , and a phase between the MMF and the magnetic flux is set to φ.sub.mc1. When the magnetic circuit operates stably, a reluctance value R.sub.mc and an initial magnetic-inductance value L.sub.mc0 in the magnetic circuit are calculated by using a formula {dot over (F)}=(R.sub.mc+jωL.sub.mc0){dot over (Φ)}. According to the calculated reluctance value R.sub.mc and a designed target magnetic impedance angle φ.sub.mc1, a target magnetic-inductance value L.sub.mc1 is calculated by using a formula φ.sub.mc1=arctan(ωL.sub.mc1/R.sub.mc). A magnetic-inductance value L.sub.mc2=L.sub.mc−L.sub.mc0that needs to be increased in the magnetic circuit is calculated based on a difference between the initial magnetic-inductance value and the target magnetic-inductance value. The number of turns N.sub.r and the resistance R.sub.r of the short-circuit coil are selected according to a calculation formula L.sub.mc2=N.sub.r.sup.2/R.sub.r for the magnetic-inductance value, and the material, length, and cross-sectional area of the short-circuit coil are selected according to the resistance value R.sub.r of the short-circuit coil. According to the physical properties of the selected short-circuit coil, the magnetic-inductance component is connected in series or in parallel in the magnetic circuit, thus completing the addition of the magnetic-inductance component to the magnetic circuit. If there are many branches in the magnetic circuit, a magnetic-inductance component can be added to each branch according to actual needs of the branch.

[0032] In a magnetic circuit formed by a transformer, an amplitude of a target magnetic flux is set to ||{dot over (Φ)}.sub.1||=0.5T , and a target magnetic impedance angle is set to φ.sub.mc1=58°. An initial magnetic circuit is changed into a target magnetic circuit by adding a magnetic-inductance component to the magnetic circuit. The flowchart is as shown in FIG. 3. First, an excitation frequency of the transformer is set to f.sub.1=50 Hz , and an excitation voltage of the transformer is set to {dot over (U)}.sub.1. When the transformer operates stably, waveforms of an excitation current İ.sub.1 and a magnetic flux {dot over (Φ)}.sub.1 of the magnetic circuit are as shown in FIG. 4. According to a formula {dot over (F)}.sub.1=(R.sub.mc+jωL.sub.mc0){dot over (Φ)}.sub.1, a reluctance value R.sub.mc of the magnetic circuit can be solved. An initial magnetic-inductance value is L.sub.mc0=43.34Ω.sup.−1, and an initial magnetic impedance angle φ.sub.mc0=31.1° can be obtained by using φ.sub.mc0=arctan(ωL.sub.mc0/R.sub.mc). Because the reluctance value R.sub.mc of the magnetic circuit is related to the excitation frequency f.sub.1 of the magnetic circuit and the magnetic flux {dot over (Φ)}.sub.1 of the magnetic circuit, the reluctance R.sub.mc basically does not change when the excitation frequency and the magnetic flux remain unchanged. A target magnetic-inductance value L.sub.mc1=111.75Ω.sup.−1 can be obtained according to the target magnetic impedance angle φ.sub.mc1=58° and a formula ωL.sub.mc1 =R.sub.mctan φ.sub.mc1. Therefore, the magnetic-inductance value that should be increased in the magnetic circuit is L.sub.mc2=L.sub.mc1−L.sub.mc0=68.35Ω.sup.−1.

[0033] By designing the arrangement and combination of the number of turns, material, length, and cross-sectional area of the multi-turn short-circuit coil, a plurality of multi-turn short-circuit coils that meet the requirements can be obtained. In the present invention, one turn of copper wire with a cross-sectional diameter of 0.5 mm is selected as the magnetic-inductance component to be connected in series in the magnetic circuit. The selected short-circuit coil is measured by using a milliohm meter, and the measured resistance value is 14.63 mΩ.

[0034] According to the calculation formula

[00007]$L_{mc}=\frac{N_r^2}{R_r}$

for the magnetic-inductance, the magnetic-inductance value is 68.353 Ω.sup.−1, which meets the requirements on the required magnetic-inductance component.

[0035] An equivalent magnetic circuit diagram to which the magnetic-inductance component is added is shown in FIG. 5. When the excitation voltage {dot over (U)}.sub.1 is stable, the magnetic flux in the magnetic circuit of the transformer remains unchanged. A waveform diagram of the MMF F.sub.N1and the magnetic flux {dot over (Φ)}.sub.1 in the magnetic circuit of the transformer after the addition of the magnetic-inductance component is shown in FIG. 6. It can be seen that in this case, the magnetic impedance angle of the magnetic circuit of the transformer reaches the target magnetic impedance angle φ.sub.mc1, and the magnetic flux reaches the target magnetic flux {dot over (Φ)}.sub.1.

[0036] In summary, the present invention provides a magnetic-inductance component. The above are only the preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. However, all equivalent modifications or changes made by a person of ordinary skill in the art based on the disclosure of the present invention should fall within the protection scope described in the claims.