A variable inductor based on adjustable permanent magnet and its verification method

Abstract

The present invention discloses a variable inductor based on an adjustable permanent magnet and a verification method thereof, which belongs to the field of inductance, and comprises two openings and oppositely arranged magnetic cores, two main power inductor windings are respectively wound around the outer sides of the two side columns of the magnetic core, one end of the two main power inductor windings are mutually connected in series, and the other ends of the two main power inductor windings are both electrically connected to an AC power supply; an adjustable permanent magnet is inlaid on the middle column of the magnetic core, a pulse magnetic modulation winding is wound around the outer side of the middle column inlaid with the adjustable permanent magnet, and the pulse magnetic modulation winding is electrically connected to a pulse power supply circuit for adjusting the peak value of the pulse current. The present invention adopts the above-mentioned variable inductor based on an adjustable permanent magnet and a verification method thereof, and can change the magnetic field strength of the adjustable permanent magnet by changing the pulse magnetic modulation current, thereby reducing the loss, and at the same time reducing the power level, volume and heat generation of the circuit matched with the control inductance value, further increasing the application scope of the variable inductor.

Description

Technical Field

[0001] The present invention relates to the field of inductance technology, and in particular to a variable inductance based on an adjustable magnetic permanent magnet and a verification method thereof. Background Art

[0002] In power circuits, the main function of inductors is to isolate and filter AC signals or form resonant circuits with capacitors, resistors, etc., and inductors are divided into variable inductors and fixed inductors according to whether the inductance value is variable.

[0003] At the same time, with the development of power electronics technology, the operating conditions of converters are becoming more and more complicated, such as wide gain, wide load, etc., and the efficiency requirements of converters are becoming more and more stringent; and with the increase in the span of changes in the operating conditions of various modern converters, it is difficult for converters under fixed parameters to maintain high-efficiency operation.

[0004] Based on the above reasons, the variable inductor whose inductance value can be changed is more valued by researchers than the fixed inductor. In the prior art, researchers have proposed a variety of variable inductors based on magnetic materials and applied them to different circuits to improve the performance of the converter.

[0005] like Figure 1 As shown, it can be seen that the conventional variable inductor is composed of two magnetic cores 1 with openings placed opposite to each other, a main power inductor winding 3, a DC bias winding 5 and a DC bias power supply, wherein the main power inductor winding 3 is wound on a middle column 4 with an air gap, and two identical DC bias windings 5 ​​are wound on two side columns, and one end of the two DC bias windings 5 ​​is connected to each other outside the magnetic core 1, and the other end is connected to the DC bias power supply, forming a series structure, which is controlled by the DC bias power supply. When a DC current passes through, the two DC bias windings 5 ​​simultaneously generate a clockwise magnetic flux, forming a loop in the side column 2, adjusting the saturation degree of the magnetic core of the side column 2 of the magnetic core 1, thereby causing the inductance value of the inductor to change due to the change in magnetic resistance.

[0006] However, this variable inductor has certain limitations during operation: during operation, a continuous DC bias current needs to be passed through it. On the one hand, this will generate additional current loss and heat, which will reduce the efficiency of the inductor, increase its volume, and reduce its insulation capacity; on the other hand, a matching DC bias power supply circuit is required, which increases the complexity of the system and is limited by the number of copper conductors that can be accommodated by the window area of ​​the inductor, so its adjustment range is limited. Summary of the invention

[0007] In view of the problems existing in the prior art such as the need to pass a constant direct current during operation of the variable inductor, which leads to reduced efficiency, increased heat generation, decreased insulation capability, limitation of inductor volume, and increased circuit complexity, the present invention provides a variable inductor based on an adjustable magnetic permanent magnet and a verification method thereof, which can change the magnetic field strength of the adjustable permanent magnet by changing the pulse magnetic modulation current, thereby reducing losses, and at the same time reducing the power level, volume and heat generation of the circuit supporting the control inductance value, thereby further increasing the application scope of the variable inductor.

[0008] To achieve the above-mentioned object, the present invention provides a variable inductor based on an adjustable permanent magnet, comprising two openings of a magnetic core arranged opposite to each other, two main power inductor windings are respectively wound around the outer sides of two side columns of the magnetic core, one end of the two main power inductor windings are connected in series with each other, and the other ends of the two main power inductor windings are both electrically connected to an AC power supply;

[0009] An adjustable permanent magnet is embedded in the middle column of the magnetic core, a pulse magnetic modulation winding is wound around the outer side of the middle column embedded with the adjustable permanent magnet, and the pulse magnetic modulation winding is electrically connected to a pulse power supply circuit for adjusting the peak value of the pulse current;

[0010] An air gap is provided on the center column;

[0011] During operation, the magnetic flux generated by the adjustable permanent magnet passes through the two side columns of the magnetic core and the main power inductor winding. By changing the magnitude of the pulse current passed through the pulse magnetic modulation winding, the magnetic flux generated by the AlNiCo permanent magnet is changed, causing the side columns to be saturated or desaturated, thereby changing the inductance value.

[0012] Preferably, the adjustable permanent magnet is an aluminum nickel cobalt permanent magnet, a ferrite permanent magnet, an aluminum nickel permanent magnet, a samarium cobalt permanent magnet, an iron cobalt vanadium permanent magnet, an iron cobalt manganese permanent magnet, an iron chromium cobalt permanent magnet or a neodymium iron boron permanent magnet;

[0013] Alnico permanent magnets include LN series, LNG series, LNGT series and LNGTJ series.

[0014] Preferably, the magnetic flux directions generated by the two main power inductor windings are the same, and the magnetic flux direction generated by the AlNiCo permanent magnet is the same as the magnetic flux direction generated by one of the main power inductor windings, and opposite to the magnetic flux direction generated by the other main power inductor winding.

[0015] Preferably, the magnetic core, two main power inductor windings and the pulse magnetic modulation winding are all integrated inside the outer shell bracket, and a pin assembly is provided on the outer shell bracket, the pin assembly includes a first pin group for connecting the two main power inductor windings in series, a second pin group for leading out the two main power inductor windings, and a third pin group for leading out the pulse magnetic modulation winding.

[0016] Preferably, the main power inductor winding and the pulse magnetic modulation winding are both made of Litz wire, silk-covered wire or copper wire;

[0017] According to the material, the magnetic core is a ferrite core made of an iron oxide mixture or a magnetic core made of one of silicon steel, steel, iron, amorphous and nanocrystalline alloys; the ferrite core includes a manganese-zinc ferrite core, a nickel-zinc ferrite core, an iron powder core, an iron-silicon-aluminum powder core, a high magnetic flux magnetic powder core, and a Permalloy core;

[0018] According to the shape, the magnetic core includes PQ core, E core, RM core, EP core, PM core, P core, U core, UI core, UU core and ring core;

[0019] The shell bracket is made of epoxy resin ABS plastic material, PLA plastic material, acrylic glass material, nylon aluminum powder material, and ceramic material.

[0020] Preferably, the two main power inductor windings are isolated from the pulse magnetic modulation winding by insulating tape.

[0021] A method for verifying variable inductance based on an adjustable permanent magnet comprises the following steps:

[0022] S1. According to Ampere's circuit theorem:

[0023]

[0024] In the formula, is the magnetic field strength generated by the current; is the differential unit on the integral path;

[0025] Right now:

[0026] H al l al +H fe δ fe +H0δ0+N pl I pl =0 (2)

[0027] In the formula, H al , H fe and H0 are the magnetic field intensities on the AlNiCo permanent magnet, the magnetic core, and the air gap, respectively; l al is the length of the AlNiCo permanent magnet; δ fe , δ0 are the magnetic path lengths in the core and in the air gap respectively; N pl is the number of turns of the pulse magnetic modulation winding; I pl is the pulse current amplitude, in A;

[0028] Combined with the magnetic circuit theorem:

[0029] F=Hδ=Rm Φ (3)

[0030]

[0031] Where F is the magnetomotive force, in A turns; H is the average magnetic field strength, in A / m; δ is the average air gap length, in m; R m is the magnetic resistance, unit is AT / Wb; Φ is the magnetic flux, unit is Wb; μ0 is the vacuum permeability, unit is H / m; μ r is the relative magnetic permeability; S is the cross-sectional area of ​​the magnetic circuit, in m 2 ;

[0032] Corresponding to AlNiCo permanent magnet:

[0033]

[0034] Where Φ0 is the air gap flux; u0 is the vacuum permeability; S0 is the air gap cross-sectional area, S fe is the core cross-sectional area; Φ fe is the magnetic flux in the core; u r is the relative magnetic permeability;

[0035] S2. Assuming that the magnetic leakage is zero and the cross-sectional areas of all parts of the magnetic circuit are equal, then:

[0036] Φ0=Φ fe =Φ=BS (6)

[0037] For AlNiCo permanent magnets, we can get:

[0038]

[0039] In the formula, B al is the magnetic induction intensity in the AlNiCo permanent magnet; R0 is the air gap magnetic resistance; R fe is the magnetic core reluctance;

[0040] S3. According to formula (7), a working line when there is no excitation current in the magnetic circuit of the AlNiCo permanent magnet and a working line when there is an excitation current in the magnetic circuit of the AlNiCo permanent magnet are drawn on the BH curve of the AlNiCo permanent magnet, and a BH curve of the magnetic core is drawn at the same time;

[0041] S4. Based on the core BH curve, set the magnetic field strength provided by the AlNiCo permanent magnet to H. al When the magnetic field intensity and magnetic induction intensity on the two side columns are biased by the AlNiCo permanent magnet to the central symmetrical points M and N, the AC magnetic field intensity ΔH is generated in the main power inductor winding when the AC current is passed. i , the magnetic induction intensity in the two side columns will produce a change of ΔB, according to the inductance formula:

[0042]

[0043] Where, I is the input current; B is the magnetic induction intensity; S fe is the core cross-sectional area;

[0044] From formula (8), it can be concluded that the magnetomotive force provided by the AlNiCo permanent magnet has different degrees of saturation, and its The even harmonics with opposite phases in the frequency domain cancel each other out, ensuring the sinusoidal nature of the inductor and thus achieving real-time adjustment of the inductance value.

[0045] The present invention has the following beneficial effects:

[0046] 1. Since only pulse current is required, it has significant advantages in heat generation and efficiency compared with traditional solutions;

[0047] 2. The AlNiCo permanent magnet is directly embedded in the center column of the magnetic core, eliminating the need for a winding that can generate a sufficiently large DC bias magnetic field, thereby reducing the size of the inductor and expanding the adjustment range of the inductance value.

[0048] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is the topology diagram of the traditional variable inductor.

[0050] Among them: 1. Magnetic core; 2. Side column; 3. Main power inductor winding; 4. Middle column; 5. DC bias winding.

[0051] Figure 2 A topological diagram of a variable inductor based on an adjustable permanent magnet of the present invention;

[0052] Figure 3 A top view of a variable inductor based on an adjustable magnetic permanent magnet according to an embodiment of the present invention;

[0053] Figure 4 is a working characteristic curve diagram of the AlNiCo permanent magnet of an embodiment of the present invention;

[0054] Figure 5 The figure is a working characteristic curve diagram of a variable inductance based on an adjustable magnetic permanent magnet according to an embodiment of the present invention.

[0055] Among them: 1. Magnetic core; 2. Side column; 3. Main power inductor winding; 4. Adjustable permanent magnet; 5. Pulse magnetic modulation winding; 6. Air gap. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical scheme and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0057] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or devices.

[0058] Like reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0059] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0060] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] like Figure 2As shown, a variable inductor based on an adjustable permanent magnet comprises two openings of a magnetic core 1 arranged opposite to each other, two main power inductor windings 3 are respectively wound around the outer sides of two side columns 2 of the magnetic core 1, one ends of the two main power inductor windings 3 are connected in series with each other, and the other ends of the two main power inductor windings 3 are electrically connected to an AC power supply; an adjustable permanent magnet 4 is embedded on the middle column of the magnetic core 1, a pulse magnetic modulation winding 5 is wound around the outer side of the middle column embedded with the adjustable permanent magnet 4, and the pulse magnetic modulation winding 5 is electrically connected to a pulse power supply circuit for adjusting the peak value of the pulse current; an air gap 6 is provided on the middle column to increase the magnetic resistance between the magnetic circuit of the permanent magnet and the main power magnetic circuit;

[0062] During operation, the magnetic flux generated by the adjustable permanent magnet 4 passes through the two side columns 2 of the magnetic core 1 and the main power inductor winding 3. By changing the size of the pulse current passed through the pulse magnetic modulation winding 5, the magnetic flux generated by the AlNiCo permanent magnet is changed, so that the side column 2 is saturated or desaturated (within one cycle, the magnetic resistance on the two side columns 2 is saturated for half a cycle respectively, thereby ensuring the sinusoidal nature of the inductor and realizing the controllable inductance value of the inductor), thereby changing the inductance value.

[0063] The adjustable permanent magnet 4 is an aluminum nickel cobalt permanent magnet, a ferrite permanent magnet, an aluminum nickel permanent magnet, a samarium cobalt permanent magnet, an iron cobalt vanadium permanent magnet, an iron cobalt manganese permanent magnet, an iron chromium cobalt permanent magnet or a neodymium iron boron permanent magnet;

[0064] Among them, the AlNiCo permanent magnets include LN series, LNG series, LNGT series and LNGTJ series.

[0065] In this embodiment, the brand of the aluminum nickel cobalt permanent magnet is LN10, LNG12, LNG13, LNG18, LNG37, LNG40, LNG44, LNG52, LNG56, LNG60, LNGT18, LNGT30, LNGT32, LNG138, LNGT44, LNGT48 LNGT60, LNGT72, LNGT88, LNGT36J or LNGT52J.

[0066] It has the characteristics of low coercive force and high remanence. Since the inductance is generated by the remanence of the internal adjustable permanent magnet 4 to generate the magnetic flux circuit in the inductor core, the remanence of the adjustable permanent magnet 4 can be changed by passing a certain pulse current through the pulse magnetization winding 5 wound on its surface, without the need to apply a constant DC bias current.

[0067] The magnetic flux directions generated by the two main power inductor windings 3 are the same, and the magnetic flux direction generated by the AlNiCo permanent magnet is the same as the magnetic flux direction generated by one of the main power inductor windings 3 and opposite to the magnetic flux direction generated by the other main power inductor winding 3 .

[0068] like Figure 3As shown, the magnetic core 1, two main power inductor windings 3 and the pulse magnetic modulation winding 5 are all integrated inside the outer shell bracket, and a pin assembly is arranged on the outer shell bracket, and the pin assembly includes a first pin group for connecting the two main power inductor windings 3 in series, a second pin group for leading out the two main power inductor windings 3, and a third pin group for leading out the pulse magnetic modulation winding 5.

[0069] The main power inductor winding 3 and the pulse magnetic modulation winding 5 are both made of Litz wire, silk-covered wire or copper wire; in this embodiment, the main power inductor winding 3 is made of 0.1mm*100 Litz wire, and the pulse magnetic modulation winding 5 is made of 0.1mm*35 Litz wire;

[0070] According to the material, the magnetic core 1 is a ferrite core made of an iron oxide mixture or a magnetic core made of one of silicon steel, steel, iron, amorphous and nanocrystalline alloys; the ferrite core includes a manganese-zinc ferrite core, a nickel-zinc ferrite core, an iron powder core, an iron silicon aluminum powder core, a high magnetic flux magnetic powder core, and a Permalloy core;

[0071] According to the shape, the magnetic core 1 includes PQ magnetic core, E magnetic core, RM magnetic core, EP magnetic core, PM magnetic core, P magnetic core, U magnetic core, UI magnetic core, UU magnetic core, and ring magnetic core;

[0072] The shell bracket is made of epoxy resin ABS plastic material, PLA plastic material, acrylic glass material, nylon aluminum powder material, and ceramic material.

[0073] The lead wires in this embodiment are all equipped with chevron sleeves / nylon insulation tubes. The fixing method is glue point fixing plus tape fixing. The overall size is 31mm in height, 36mm in length, and 26mm in width.

[0074] The two main power inductor windings 3 and the pulse magnetic modulation winding 5 are isolated by insulating tape.

[0075] The following description is made by taking the adjustable permanent magnet as an AlNiCo permanent magnet and the magnetic core 1 as an E-type magnetic core as an example:

[0076] A method for verifying variable inductance based on an adjustable permanent magnet comprises the following steps:

[0077] S1. According to Ampere's circuit theorem:

[0078]

[0079] In the formula, is the magnetic field strength generated by the current; is the differential unit on the integral path;

[0080] Right now:

[0081] H al l al+H fe δ fe +H0δ0+N pl I pl =0 (2)

[0082] In the formula, H al , H fe and H0 are the magnetic field strengths on the AlNiCo permanent magnet, the magnetic core 1, and the air gap 6 respectively; l al is the length of the AlNiCo permanent magnet; δ fe , δ0 are the magnetic path lengths in the core 1 and the air gap 6 respectively; N pl is the number of turns of the pulse magnetic modulation winding 5; I pl is the pulse current amplitude, in A;

[0083] Combined with the magnetic circuit theorem:

[0084] F=Hδ=R m Φ (3)

[0085]

[0086] Where F is the magnetomotive force, in A turns; H is the average magnetic field strength, in A / m; δ is the average air gap length, in m; R m is the magnetic resistance, unit is AT / Wb; Φ is the magnetic flux, unit is Wb; μ0 is the vacuum permeability, unit is H / m; μ r is the relative magnetic permeability; S is the cross-sectional area of ​​the magnetic circuit, in m 2 ;

[0087] Corresponding to AlNiCo permanent magnets:

[0088]

[0089] Where Φ0 is the air gap flux; u0 is the vacuum permeability; S0 is the air gap cross-sectional area, S fe is the core cross-sectional area; Φ fe is the magnetic flux in the core; u r is the relative magnetic permeability;

[0090] S2. Assuming that the magnetic leakage is zero and the cross-sectional areas of all parts of the magnetic circuit are equal, then:

[0091] Φ0=Φ fe =Φ=BS (6)

[0092] For AlNiCo permanent magnets, we can get:

[0093]

[0094] In the formula, B alis the magnetic induction intensity in the AlNiCo permanent magnet; R0 is the air gap magnetic resistance; R fe is the magnetic core reluctance;

[0095] S3. According to formula (7), a working line (working line 1) when there is no excitation current in the magnetic circuit of the AlNiCo permanent magnet and a working line (working line 2) when there is an excitation current in the magnetic circuit of the AlNiCo permanent magnet are drawn on the BH curve of the AlNiCo permanent magnet, and a BH curve of the magnetic core 1 is drawn at the same time;

[0096] like Figure 4 As shown in the figure, the working characteristics of AlNiCo permanent magnets change with the peak value of the pulse magnetization current: when the magnetic field intensity provided by the peak value of the pulse current in the AlNiCo permanent magnet exceeds any point B after the inflection point of the AlNiCo hysteresis loop, when the magnetization current returns to zero, the AlNiCo permanent magnet will not return to the initial working point A along the hysteresis loop, but will come to the new working point C along the recovery line. With the magnitude of the magnetization current, the AlNiCo permanent magnet will be on different recovery lines and eventually stabilize at different working points. These working points will provide different magnetic induction intensities B to the magnetic core, causing the saturation degree of the magnetic core to change.

[0097] S4, based on Figure 5 The core 1BH curve shown is set when the magnetic field strength provided by the AlNiCo permanent magnet is H al When the magnetic field intensity and magnetic induction intensity on the two side columns 2 are biased by the AlNiCo permanent magnet to the central symmetrical points M and N, the AC magnetic field intensity ΔH is generated in the main power inductor winding 3 when the AC current is passed. i , the magnetic induction intensity in the two side columns 2 will produce a change of ΔB, according to the inductance formula:

[0098]

[0099] Where, I is the input current; B is the magnetic induction intensity; S fe is the core cross-sectional area;

[0100] From formula (8), it can be concluded that the magnetomotive force provided by the AlNiCo permanent magnet has different degrees of saturation, and the magnetomotive force on the two side columns 2 is The even harmonics with opposite phases in the frequency domain cancel each other out, ensuring the sinusoidal nature of the inductor and thus achieving real-time adjustment of the inductance value.

[0101] Example

[0102] In this embodiment, twelve pins are provided, the main power inductor winding 3 input wire is welded to the 1 / 2 pin, the main power inductor winding 3 middle output wire is welded to the 3 / 4 pin, and the 3 / 4 pin is unplugged, the main power inductor winding 3 input wire on one side column 2 is welded to the 5 / 6 pin, and the winding middle output wire is also welded to the 3 / 4 pin. And each side column 2 is wound with 5 turns of coil.

[0103] The pulse magnetic modulation winding 5 input wire is welded to the 9th pin, the winding output wire is welded to the 10th pin, and 15 turns are wound.

[0104] Use pins 1 / 2 as input terminals and pins 5 / 6 as output terminals, and weld them to a power supply or other required scenarios as an inductor. By inputting pulse current into the loop formed by pins 9 and 10, the magnetization state of the permanent magnet can be changed, thereby changing the inductance value from the inductor to the outside in real time.

[0105] Therefore, the present invention adopts the above-mentioned variable inductor based on adjustable magnetic permanent magnet and its verification method, which can change the magnetic field strength of the adjustable permanent magnet by changing the pulse magnetization current, and utilize the extremely small loss characteristic generated by pulse current control to replace the introduction of a constant DC bias current to further change the magnetic resistance in the inductor power circuit, thereby reducing the loss and reducing the power level, volume and heat generation of the circuit supporting the control inductance value, thereby further increasing the application scope of the variable inductor.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A variable inductor based on an adjustable permanent magnet, comprising two openings of a magnetic core arranged opposite to each other, characterized in that: Two main power inductor windings are respectively wound around the outer sides of the two side columns of the magnetic core, one end of the two main power inductor windings are connected in series with each other, and the other ends of the two main power inductor windings are electrically connected to the AC power supply; An adjustable permanent magnet is embedded in the middle column of the magnetic core, a pulse magnetic modulation winding is wound around the outer side of the middle column embedded with the adjustable permanent magnet, and the pulse magnetic modulation winding is electrically connected to a pulse power supply circuit for adjusting the peak value of the pulse current; An air gap is provided on the center column; When working, the magnetic flux generated by the adjustable permanent magnet passes through the two side columns of the magnetic core and the main power inductor winding. By changing the magnitude of the pulse current passed into the pulse magnetic modulation winding, the magnetic flux generated by the AlNiCo permanent magnet is changed, so that the side columns are saturated or desaturated, thereby changing the inductance value. The magnetic flux directions generated by the two main power inductor windings are the same, and the magnetic flux direction generated by the AlNiCo permanent magnet is the same as the magnetic flux direction generated by one of the main power inductor windings, and opposite to the magnetic flux direction generated by the other main power inductor winding. In one cycle, the magnetic resistance on the two side columns is saturated for half a cycle respectively.

2. The variable inductor based on adjustable permanent magnet according to claim 1, characterized in that: The adjustable permanent magnet is an aluminum nickel cobalt permanent magnet, a ferrite permanent magnet, an aluminum nickel permanent magnet, a samarium cobalt permanent magnet, an iron cobalt vanadium permanent magnet, an iron cobalt manganese permanent magnet, an iron chromium cobalt permanent magnet or a neodymium iron boron permanent magnet; Alnico permanent magnets are LN series, LNG series, LNGT series or LNGTJ series.

3. The variable inductor based on adjustable permanent magnet according to claim 1, characterized in that: The magnetic core, two main power inductor windings and the pulse magnetic modulation winding are all integrated inside the outer shell bracket. A pin assembly is arranged on the outer shell bracket. The pin assembly includes a first pin group for connecting the two main power inductor windings in series, a second pin group for leading out the two main power inductor windings, and a third pin group for leading out the pulse magnetic modulation winding.

4. The variable inductor based on adjustable permanent magnet according to claim 1, characterized in that: The main power inductor winding and pulse magnetic modulation winding are made of Litz wire, silk-covered wire or copper wire; According to the material, the magnetic core is a ferrite core made of an iron oxide mixture or a magnetic core made of one of silicon steel, steel, iron, amorphous and nanocrystalline alloys; the ferrite core includes a manganese-zinc ferrite core, a nickel-zinc ferrite core, an iron powder core, an iron-silicon-aluminum powder core or a Permalloy core; According to the shape, the core includes PQ core, E core, RM core, EP core, PM core, P core, U core, UI core or ring core; The shell bracket is made of epoxy resin ABS plastic material, PLA plastic material, acrylic glass material, nylon aluminum powder material or ceramic material.

5. The variable inductor based on adjustable permanent magnet according to claim 1, characterized in that: The two main power inductor windings are isolated from the pulse magnetic modulation winding by insulating tape.

6. A method for verifying variable inductance based on an adjustable permanent magnet as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1. According to Ampere's circuit theorem: In the formula, is the magnetic field strength generated by the current; is the differential unit on the integral path; Right now: H al l al +H fe d fe +H0δ0+N pl I pl =0 (2) In the formula, H al , H fe and H0 are the magnetic field intensities on the AlNiCo permanent magnet, the magnetic core, and the air gap, respectively, in A / m; l al is the length of the AlNiCo permanent magnet; δ fe , δ0 are the magnetic path lengths in the core and in the air gap respectively; N pl is the number of turns of the pulse magnetic modulation winding; I pl is the pulse current amplitude, in A; Combined with the magnetic circuit theorem: F=Hδ=R m F (3) Where F is the magnetomotive force, in A turns; H is the average magnetic field strength, in A / m; δ is the average air gap length, in m; R m is the magnetic resistance, unit is AT / Wb; Φ is the magnetic flux, unit is Wb; μ0 is the vacuum permeability, unit is H / m; μ r is the relative magnetic permeability; S is the cross-sectional area of ​​the magnetic circuit, in m 2 ; Corresponding to AlNiCo permanent magnets: Where Φ0 is the air gap flux; u0 is the vacuum permeability; S0 is the air gap cross-sectional area, S fe is the core cross-sectional area; Φ fe is the magnetic flux in the core; u r is the relative magnetic permeability; S2. Assuming that the magnetic leakage is zero and the cross-sectional areas of all parts of the magnetic circuit are equal, then: Φ0=Φ fe =Φ=BS (6) For AlNiCo permanent magnets, we can get: In the formula, B al is the magnetic induction intensity of AlNiCo; R0 is the air gap magnetic resistance; R fe is the magnetic core reluctance; S3. According to formula (7), a working line when there is no excitation current in the magnetic circuit of the AlNiCo permanent magnet and a working line when there is an excitation current in the magnetic circuit of the AlNiCo permanent magnet are drawn on the BH curve of the AlNiCo permanent magnet, and a BH curve of the magnetic core is drawn at the same time; S4. Based on the core BH curve, set the magnetic field strength provided by the AlNiCo permanent magnet to H. al When the magnetic field intensity and magnetic induction intensity on the two side columns are biased by the AlNiCo permanent magnet to the central symmetrical points M and N, the AC magnetic field intensity ΔH is generated in the main power inductor winding when the AC current is passed. i , the magnetic induction intensity in the two side columns will produce a change of ΔB, according to the inductance formula: Where, I is the input current; B is the magnetic induction intensity; S fe is the cross-sectional area of ​​the magnetic circuit of the core; From formula (8), it can be concluded that the magnetomotive force provided by the AlNiCo permanent magnet has different degrees of saturation, and its The even harmonics with opposite phases in the frequency domain cancel each other out, ensuring the sinusoidal nature of the inductor and thus achieving real-time adjustment of the inductance value.

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