WO2025264264A1

WO2025264264A1 - Misaligned control and enhancement of inductors

Info

Publication number: WO2025264264A1
Application number: PCT/US2025/000015
Authority: WO
Inventors: Al-Thaddeus Avestruz; Peter Noble TAWIAH-MENSAH; Xiaofan Cui
Original assignee: University of Michigan System
Current assignee: University of Michigan System
Priority date: 2024-06-21
Filing date: 2025-06-23
Publication date: 2025-12-26
Anticipated expiration: 2026-12-21

Abstract

A system includes a control inductor and a variable inductor. The control inductor is configured to generate a control magnetic field across a channel in which the variable inductor is disposed. The control magnetic field is generated along a control axis within the channel. The control axis is misaligned with an operating axis along which the variable inductor generates an operating magnetic field when in operation.

Description

MISALIGNED CONTROL AND ENHANCEMENT OF INDUCTORS

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0001] This invention was made with government support under 2146490 awarded by the National Science Foundation. The government has certain rights in the invention.

BACKGROUND

Priority

[0002] This application claims priority to U.S. Provisional Patent Application No. 63/662,905, filed June 21 , 2024, and titled ORTHOGONAL CONTROL AND ENHANCEMENT OF INDUCTORS, which is incorporated by reference herein in its entirety.

Technical Field

[0003] The disclosure relates generally to misaligned control of inductors.

Brief Description of Related Technology

[0004] Increasingly complex electronics have given rise to a need for power conversion and other variable inductor applications. For example, devices including power supply circuitry may power components at various power levels and/or other input constraints. However, variable inductor performance may affect overall device performance. Accordingly, there is increasing demand for systems that efficiently and accurately perform impedance matching, resonance matching, and/or other variable inductor applications. Improvements to temperature analysis which improve overall device performance and increase demand.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 shows an example misaligned variable inductor (MVI).

[0006] Figure 2 shows example MVI logic.

[0007] Figure 3 shows an example MVI power converter.

[0008] Figure 4 shows an example complementary MVI (CMVI).

[0009] Figure 5 shows an example dual inductor CMVI. [0010] Figure 6 shows an example magnetic material CMVI.

[0011] Figure 7 shows an example permanent magnet CMVI.

[0012] Figure 8 shows an example blended CMVI (BCMVI).

[0013] Figure 9 shows a second example BCMVI.

[0014] Figure 10 shows a third example BCMVI.

DETAILED DESCRIPTION

[0015] In various contexts, a variable inductor may be used within various electronic systems. Variable inductors may be used in various applications such as lighting applications, wireless charging, and/or other power electronics. A control magnetic field, such as DC (direct current) bias field, may be applied to the core of variable inductor lowering the permeability of the inductor core and as a result of the inductance of the inductor core.

[0016] The conventional wisdom provides that the control magnetic field may be produced by a control inductor aligned with the variable inductor. This provides a compact and cost efficient design where the control inductor and variable inductor may be implemented as a pair of separate windings that share the same core.

[0017] As recognized herein, although various schemes may be implemented to reduce coupling between the variable and control currents within the respective inductors at a cost of device compactness, these mitigations result in increased fringing effects. Thus a trade-off remains even with a scheme to reduce coupling between the currents within the inductors. As recognized herein, misaligned (e.g., at least partially orthogonally oriented) control and variable inductors have magnetic fields that are misaligned (e.g., at least partially orthogonally oriented). Thus, the level of coupling between the respective currents within the inductors may be controlled via selection of the misalignment of the magnetic fields produced by the inductors. As also recognized herein, misalignment (additionally or alternatively) allows for airgap placement of the variable inductor to allow the control magnetic field to be applied uniformly to the variable inductor.

[0018] In various implementations, misalignment between the inductors may be partial or full. Full misalignment may correspond to inductors oriented such that their induced magnetic fields are fully orthogonal. Partial misalignment may refer to a misalignment that in less than full that nevertheless has a functional design effect on the operation of the variable inductor. In some cases, misalignment may be selected to result in negligible magnetic flux through windings of the respective inductors. A negligible magnetic flux (e.g., through a inductor winding) may correspond to a magnetic flux below a pre-defined tolerance, a zero or near zero magnetic flux level, a magnetic flux that produces effect below that is undetectable, and/or other level where device performance can be accurately assessed without consideration of the contributions from the magnetic flux.

[0019] Figure 1 shows an example misaligned variable inductor (MVI) 100. The MVI 100 includes a control inductor 110 with a control inductor core 112. The control inductor 110 is proximate to a channel 114 (e.g., such as an air gap) in which the variable inductor 120 is disposed. The control inductor 110 may be positioned relative to the channel such that the control magnetic field 116 induced by the control inductor 110 extend across the channel, e.g., such that the control magnetic field 116 may permeate through the variable inductor 120 and the variable inductor core 122 when the control magnetic field 116 is induced by the control inductor 110. The variable inductor may induce an operating magnetic field 126, which may be misaligned (fully or in part) with the control magnetic field. In various implementations, the variable inductor core 122 may be toroidal. In various implementations, the variable inductor core 122 may be cylindrical. In some cases, the core material {for variable inductor 120 and/or the control inductor 110 may include a magnetic material (e.g. a ferromagnetic material, such i as steel or other ferromagnetic material, a ferrimagnetic material, and/or a magnetic composite) and/or a permanent magnet. In various implementations, the control inductor 110 and control inductor 112 can be replaced by a permanent Hagnet, which can be fixed in position or positioned using various means which may include mechanical means which may include manually or using an actuator which may include piezoelectrics.

[0020] In various implementations, the coupling between the inductors may be variable. For example variable coupling coefficients may be selected (e.g., via design parameters, via field misaligment level (e.g., dynamically via actuation or statically), and/or via other selection parameter.

[0021] In various implementations, the control magnetic field may be implemented to enhance an efficiency (e.g., via increased quality factor and/or reduced core losses) of a target inductor. The enhancement may be achieved with or without support for variable inductor operation. In other words, in various implementations, the misaligned control magnetic field may be used solely to enhance performance of the target (but-not-technically variable) inductor or (in at least some other implementations) may be used to enhance performance in concert with variable operation.

[0022] In various implementations, the variable inductor 120 and the control inductor 110 may include multiple windings (e.g., to form coil-type inductors). The variable inductor 120 and the control inductor 110 may be oriented with respect to one another such that their respective operating 126 and control 116 magnetic fields produce negligible magnetic field flux through the windings of the other inductor. In other words, the contribution to the magnetic field flux through the variable inductor windings 128 by the control magnetic field 116 is negligible and/or the contribution to the magnetic field flux through the control inductor windings 118 by the operating magnetic field 126 is negligible. Thus, in at least some cases, the effect of the control magnetic field 116 on the variable inductor 120 may be isolated to the reduction in permeability of the variable inductor core 122 (while at least some other effects, which may lower variable inductor efficiency if present, are eliminated).

[0023] Figure 2 shows example MVI logic 200 to support MVI 100 operation. The example MVI logic 200 cause provision (e.g., by driving current through a control inductor) of the control magnetic field 116 across the channel 114 at a first level (202).

[0024] The example MVI logic 200 may vary the inductance of the variable inductor by causing adjustment of the control magnetic field 116 across the channel 11 to a second level different from the first level (204). In various implementations’, the shift in the level (e.g., field strength) of the control magnetic field may be effected by changing the current level being driven through the control inductor. The change from the first level to the second level for control magnetic field changes the permeability of the variable inductor core 122. Thus, the variable inductor has a first inductance associated with first level and a second inductance associated with second level. In various implementations, varying the control magnetic field 116 over a continuous strength spectrum may allow for continuously variable operation from the variable inductor 120. Conversely, discrete targeting control magnetic field 116 strength may allow for discrete level operation of the variable inductor 120.

[0025] Figure 3 shows an example MVI power converter 1300. The example MVI power converter 300 may include two switches (Q1 302 and Q2 304), two diodes (D1 312 and D2 314), a resonant capacitor (Cr 306), and a MVI (MVI 308). ■

[0026] During state 1 , Q1 is on and Q2 is off. Switch State 2 marks the first resonant transition when both switches Q1 and Q2 are off. In this state, the resonant capacitor is completely discharged. In Switch State 3, Q2 is turned on, and resonant inductor current reduces linearly. It is in this state that the current in the resonant inductor can be made to go negative, enabling ZVS (zero voltage switching) operation. Switch state 4 is another resonant transition as Q2 is turned off while Q1 is still off. In state 4, Cr is charged from zero voltage level to Vg. Switch State 5 is enabled via the choice of resonant tank and supports operation of ZVS. In this state, the diode D1 conducts, right before Q1 is turned on in Switch State 1 for ZVS. [0027] Figure 4 shows an example complementary MVI (CMVI) 400. The example complementary MVI 400 includes a complement structure 402. The complement structure 402 may support generation of the control magnetic field 116. In various implementations, the complement structure may enhance field strength, field generation efficiency, field uniformity, field confinement within the channel 114, and/or otherwise enhance performance of field generation. In various implementations, the complement structure 402 may be disposed on the side of the channel opposite the control inductor 110. Nevertheless in various other examples, the complement structure may be disposed on other sides of the channel, including (at least in part) on the same side of the channel as the control inductor 110.

[0028] Figure 5 shows an example dual inductor CMVI 500. In the example dual inductor CMVI 500, the complement structure 502 may include a second control inductor that may operate in concert with the control inductor 110.

[0029] Figure 6 shows an example magnetic material CMVI 600. In the example magnetic material CMVI 600 complementary structure 602 may include one or more blocks of magnetic material (e.g., a ferromagnetic material, such as steel or other ferromagnetic material, a ferrimagnetic material, and/or a magnetic composite) may be disposed an any side of the

I channel 114. The presence of the magnetic material may assist in efficient confinement of the control magnetic field to ensure the field strength is focused within the channel 114.

[0030] Figure 7 shows an example permanent magnet CMVI 700. In the example permanent magnet CMVI 700, the complementary structure 702 may include one or more permanent magnets. The presence of the permanent magnets provide a baseline control magnetic field that shifts the set point for operations of the example permanent magnet CMVI 700. Thus, the setpoint of the example permanent magnet CMVI 700 may be selected based on efficient operation for the particular application of the example permanent magnet CMVI 700. Permanent magnets may be disposed throughout the example permanent magnet CMVI 700 at any of various locations.

[0031] The structures of the various CMVIs may be combined, for example permanent magnets may be placed proximate to magnetic material blocks to form a structure having a permanent magnet and a magnetic material block. Similarly, permanent magnets may be paired with additional control inductors. Additionally or alternatively, magnetic material blocks may be paired with control inductors and/or permanent magnets. In various implementations, dielectric material walls (such as plastic walls) may be implemented surrounding the complement structure to create a larger flux path. [0032] Figure 11 show a second example M VI 1100. In the second example MVI 1100a misaligned magnetic field may be imposed on the magnetic core of an inductor to reduce the core losses and/or to increase the quality factor. The reduction of losses demonstrated in the plot 1200 in Figure 12 and the increase in quality factor is demonstrated in the plot 1300 in Figure 13. This misaligned magnetic field may be generated by a permanent magnet and/or an electromagnet.

[0033] A misaligned magnetic field may be imposed on the magnetic core of an inductor to change the B-H curve of the inductor’s magnetic core. This misaligned magnetic field can be generated by a permanent magnet, an electromagnet, and/or other magnetic field source. Where the control magnetic field source 1110 (e.g., permanent magnet and/or an electromagnet) has a fixed field output level, an actuator 1112 (e.g., a piezo, a translation stage, galvo, and/or other motive system) shift the relative position of the permanent magnet and/or an electromagnet to cause the change in field strength used to vary the inductance of the variable inductor 120. Figure 14 shows a plot 1400 of the B-H curve with imposed magnetic field and Figure 15 shows a plot 1500 of the B-H curve with a superimposed misaligned magnetic field.

[0034] A misaligned magnetic field may be imposed on maghetic core to control the coupling coefficient of two inductors. The inductors may share the same core, may have physically distinct cores, and/or may have an intermediate core coupling the fluxes between the two inductors.

[0035] Figure 8 shows an example blended CMVI (BCMVI) 800. The complementary structure 802 includes one or more steel blocks (or other magnetic material blocks) and a second control inductor. In various additional configurations, walls 804 may be implemented using magnetic material blocks and/or dielectric materials to control the length of the flux path for the fields.

[0036] Figure 9 shows a second example BCMVI 900. In the complementary structure 902 includes one or more steel blocks (or other magnetic material blocks) and a permanent magnet. In various additional configurations, walls 804 may be implemented using magnetic material blocks and/or dielectric materials to control the length of the flux path for the fields.

[0037] Figure 10 shows a third example BCMV1 1000. In the complementary structure 1002 includes one or more steel blocks (or other magnetic material blocks), a second control inductor, and one or more permanent magnets. In various additional configurations, walls 804 may be implemented using magnetic material blocks and/or dielectric materials to control the length of the flux path for the fields. [0038] The methods, devices, processing, and logic described above may be implemented in many different ways and in many different combinations of hardware and software. For example, all or parts of the implementations may be circuitry that includes an instruction processor, such as a microcontroller, a microprocessor, and/or circuitry that includes discrete logic or other circuit components, including analog circuit components, digital circuit components or both; or any combination thereof.

[0039] The circuitry may further include or access instructions for execution by the circuitry. The instructions may be embodied as a signal and/or data stream and/or may be stored in a tangible storage medium that is other than a transitory signal, such as a flash memory, a Random Access Memory (RAM), a Read Only Memory (ROM), an Erasable Programmable Read Only Memory (EPROM); or on a magnetic or optical disc, such as a Compact Disc Read Only Memory (CDROM), Hard Disk Drive (HDD), or other magnetic or optical disk; or in or on another machine-readable medium. A product, such as a computer program product, may particularly include a storage medium and instructions stored in or on the medium, and the instructions when executed by the circuitry in a device may cause the device to implement any of the processing described above or illustrated in the drawings.

[0040] Various implementations have been specifically described. However, many other implementations are also possible.

[0041] Table 1 shows various examples. c c c m a v o w c c o c i v v p

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[0042] The present disclosure has been described with reference to specific examples that are intended to be illustrative only and not to be limiting of thd disclosure. Changes, additions and/or deletions may be made to the examples without departing from the spirit and scope of the disclosure.

[0043] The foregoing description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom.

Claims

What is Claimed is:

1 . A device including: a control inductor configured to generate a control magnetic field across a channel proximate to the control inductor, the control magnetic aligned along a control axis; and a variable inductor disposed within the channel, the variable inductor configured to generate an operating magnetic field aligned along an operating axis, the operating axis misaligned to the control axis.

2. The device of claim 1 , wherein the device further includes a complement structure configured to support generation of the control magnetic field across the channel.

3. The device of claim 2, wherein the complement structure includes another control inductor. i

4. The device of claim 2, wherein the complement structure includes a permanent magnet.

5. The device of claim 2, wherein the complement structure includes a magnetic material block.

6. The device of claim 2, wherein the magnetic material block is surrounded by one or more windings forming another control inductor.

7. The device of claim 1 , wherein the variable inductor includes multiple windings.

8. The device of claim 7, wherein the operating axis being misaligned to the control axis includes the multiple windings being oriented relative to the control magnetic field such that the contribution to the magnetic flux through any of the multiple windings by the control magnetic field is negligible.

9. The device of claim 8, wherein the operating axis being misaligned to the control axis includes an alternating current (AC) operation of the variable inductor to oscillate around a zero point in the relation of the H-field for the variable inductor to the B-field for the variable inductor.

10. The device of claim 1 , wherein the variable inductor includes a toroidal coil including multiple windings wound in planes aligned to the control magnetic field.

11. The device of claim 1 , wherein the control magnetic field is distributed uniformly over the variable inductor.

12. A device including: a control inductor configured to generate a control magnetic field across a channel proximate to the control inductor; and a variable inductor disposed within the channel, the variable inductor including multiple windings, the multiple windings oriented relative to the control magnetic field such that the contribution to the magnetic flux through any of the multiple windings by the control magnetic field is negligible.

13. The device of claim 12, further including a complement structure disposed on an opposite side of the channel relative to the control inductor, the complement structure configured to enhance a strength of the control magnetic field across the channel.

14. The device of claim 13, wherein the complement structure includes another control inductor.

15. The device of claim 13, wherein the complement structure includes a permanent magnet.

16. The device of claim 13, wherein the complement structure includes a magnetic material block.

17. The device of claim 13, wherein the magnetic material block is surrounded by one or more windings forming another control inductor^

18. The device of claim 12, wherein the variable inductor includes a toroidal coil including multiple windings wound in planes aligned to the control magnetic field.

19. A method including: shifting an inductance of a variable inductor disposed within a channel by: providing at a first strength, a control magnetic field across the channel, the control magnetic field, when non-zero in strength, aligned along a control axis at least within the channel, an operating magnetic field generated by the variable inductor when in operation, the operating magnetic field aligned along an operating axis, the operating axis misaligned with the control axis; and ' adjusting the control magnetic field to a second strength different from the first strength to drive a shift in a permeability of a core of the variable inductor thereby shifting the inductance of the variable inductor.

20. The method of claim 19, further including operating the variable inductor within a zero-voltage-switching scheme for a power converter.