Integrated planar magnetic for high frequency regulated resonant converter

Abstract

An integrated planar magnetic for a DC to DC resonant converter has a transformer core, a first resonant inductor core and a second resonant inductor core. The first resonant inductor core and the second resonant conductor core are integrated with the transformer core, The mechanical structure of the integrated core provides a small footprint and leads to a high power density. Vertical windings are used which decreases winding losses and increases efficiency. The resonant inductor enables a relatively small Lm / Lr ratio for closed-loop regulation of a wide range input voltage DC / DC resonant converter.

Description

[0001] INTEGRATED PLANAR MAGNETIC FOR HIGH FREQUENCY REGULATED RESONANT CONVERTER

[0002] TECHNICAL FIELD

[0003] The aspects of the disclosed embodiments relate generally to power conversion apparatus and more particularly to integrated planar magnetic for DC / DC resonant converters.

[0004] BACKGROUND

[0005] The investment of cloud computing and artificial intelligence is surging rapidly. A sizable fraction is spent on the physical infrastructure that provides power for servers and data centers. DC / DC resonant converters are widely used in server and data center power supplies, since they can achieve soft-switching to provide high power density and high efficiency.

[0006] Integrated planar magnetics for resonant converters, are sophisticated power electronics systems designed to efficiently convert electrical energy from one form to another while maintaining high power density and regulations. Integrated planar magnetics, as a component of DC / DC resonant converters, can provide reduced volumes.

[0007] Typically, integrated planar magnetics of regulated resonant converters are required to have relatively small Lm / Lr ratio for the closed-loop regulation of wide range input voltage, high power density and high efficiency. While there are existing solutions that can achieve some of these requirements, there are no solutions that can meet all of these requirements at the same time.

[0008] Thus, there is a need for improved integrated planar magnetics for resonant converters. Accordingly, it would be desirable to provide methods and apparatus that addresses at least some of the problems described above.

[0009] SUMMARY

[0010] The aspects of the disclosed embodiments are directed to an integrated planar magnetic for a DC to DC resonant converter. The integrated planar magnetic of the disclosed embodiments has a high-power density due to the small footprint provided by the resonant inductor. The integrated planar magnetic of the disclosed embodiments provides high efficiency due to the use of vertical windings. In addition, the resonant inductor is a normal regular inductor which is not created by leakage. The resonant inductor enables a relatively small Lm / Lr ratio for closed-loop regulation of a wide range input voltage DC / DC resonant converter.

[0011] According to a first aspect, the above and further advantages are obtained by an integrated planar magnetic. In one embodiment, the integrated planar magnetic includes a transformer core, a first resonant inductor core and a second resonant inductor core. The first resonant inductor core and the second resonant conductor core are integrated with the transformer core. The mechanical structure of the integrated core provides a small footprint. There are three middle legs in the core. One for the transformer and the other two for the resonant inductor. The small footprint enables a high power density.

[0012] In a possible implementation form a primary winding structure of the transformer core comprises multiple layers of planar windings connected in series and a secondary winding structure of the transformer core comprises a first group of secondary windings and a second group of secondary windings. The secondary windings are separated into two groups, while maintain a small footprint and low winding loss.

[0013] In a possible implementation form the first group of secondary windings comprises a first plurality of planar windings applied to the transformer core and the first resonant inductor core. A first single turn winding is applied to the transformer core and a second single turn winding is applied to the first resonant inductor core. The secondary windings are separated into two groups, where each group has a one turn resonant inductor connected in series. The small footprint and low winding loss provides high power density and high efficiency.

[0014] In a possible implementation form the first single turn winding is a vertical winding. Vertical winding can be implemented to the transformer to reduce the winding loss caused by the magnetizing current. This increases efficiency.

[0015] In a possible implementation form, the second single turn winding is a vertical winding. The resonant inductor is a one-turn secondary side inductor with a vertical winding. The vertical winding reduces inductor winding loss and increases efficiency.

[0016] In a possible implementation form the first single turn winding and the second single turn winding are connected in series. The integrated planar magnetic of the disclosed embodiments has a high power density and high efficiency. It is suitable for closed-loop regulated wide- range-input DC / DC resonant converters.

[0017] In a possible implementation form the second group of secondary windings comprises a second plurality of planar windings applied to the transformer core and the second resonant inductor core. A third single turn winding is applied to the transformer core and a fourth single turn winding is applied to the second resonant inductor core. The secondary windings are separated into two groups, where each group has a one turn resonant inductor connected in series. The small footprint and low winding loss provides high power density and high efficiency.

[0018] In a possible implementation form the third single turn winding is a vertical winding. Vertical winding can be implemented to the transformer to reduce the winding loss caused by the magnetizing current. This increases efficiency.

[0019] In a possible implementation form, the fourth single turn winding is a vertical winding. The resonant inductor is a one-turn secondary side inductor with a vertical winding. The vertical winding reduces inductor winding loss and increases efficiency.

[0020] In a possible implementation form the third single turn winding and the fourth single turn winding are connected in series. The integrated planar magnetic of the disclosed embodiments has a high power density and high efficiency. It is suitable for closed-loop regulated wide- range-input DC / DC resonant converters.

[0021] In a possible implementation form the first single turn winding and the second single turn winding of the first group of secondary windings are connected to the first plurality of planar windings. The third single turn winding and the fourth single turn winding of the second group of secondary windings are connected to the second plurality of planar windings. The integrated planar magnetic of the disclosed embodiments has a high-power density due to the small footprint given by the one-turn resonant inductor. Using vertical windings provides high efficiency. In addition, the resonant inductor is a normal regular inductor which is not created by leakage and provides a relatively small ratio of magnetizing inductance (Lm) to resonant inductance (Lr) (Lm / Lr) for the closed-loop regulation of a wide range input voltage DC / DC resonant converter. In a possible implementation form, the primary winding structure, the first group of secondary windings and the second group of secondary windings are arranged in an up-down structure. The integrated planar magnetic of the disclosed embodiments has a higher power density due to its higher integration and higher efficiency by using vertical windings.

[0022] In a possible implementation form at least one second transformer core with a third resonant inductor core and a fourth resonant inductor core is disposed adjacent to the transformer core. The third resonant inductor core and the fourth resonant conductor core are integrated with the at least one second transformer core. The design of the integrated planar magnetic of the disclosed embodiments can be extended to matrix magnetics with different core shapes and winding connections.

[0023] In a possible implementation form a primary winding structure of the at least one second transformer core comprises multiple layers of planar windings connected in series. A secondary winding structure of the at least one second transformer core comprises a third group of secondary windings and a fourth group of secondary windings. The design of the integrated planar magnetic of the disclosed embodiments can be extended to matrix magnetics with different core shapes and winding connections.

[0024] In a possible implementation form the third group of secondary windings comprises a first plurality of planar windings applied to the at least one second transformer core and the third resonant inductor core. A fifth single turn winding is applied to the at least one second transformer core and a sixth single turn winding is applied to the third resonant inductor core. The design of the integrated planar magnetic of the disclosed embodiments can be extended to matrix magnetics with different core shapes and winding connections.

[0025] In a possible implementation form the fourth group of secondary windings comprises a fourth plurality of planar windings applied to the transformer core and the fourth resonant inductor core; a seventh single turn winding applied to the transformer core; and an eighth single turn winding applied to the first resonant inductor core.

[0026] These and other aspects, implementation forms, and advantages of the exemplary embodiments will become apparent from the embodiments described herein considered in conjunction with the accompanying drawings. It is to be understood, however, that the description and drawings are designed solely for purposes of illustration and not as a definition of the limits of the disclosed invention, for which reference should be made to the appended claims. Additional aspects and advantages of the invention will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. Moreover, the aspects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In the following detailed portion of the present disclosure, the invention will be explained in more detail with reference to the example embodiments shown in the drawings, in which like references indicate like elements and:

[0029] Figure 1 illustrates a schematic block diagram of an exemplary integrated planar magnetic incorporating aspects of the disclosed embodiments.

[0030] Figures 2A-2C illustrate exemplary arrangements of the primary winding structure and secondary winding structure for an integrated planar magnetic of the disclosed embodiments.

[0031] Figure 3 illustrates an exemplary schematic diagram of a primary winding pathway and secondary winding pathway for an integrated planar magnetic of the disclosed embodiments.

[0032] Figure 4 illustrates an equivalent circuit diagram for an integrated planar magnetic of the disclosed embodiments.

[0033] Figure 5 illustrates a cross-sectional view of integrated planar magnetic shown in Figure 1 taken along the line X-X.

[0034] Figure 6 illustrates a cross-sectional view of integrated planar magnetic shown in Figure 1 taken along the line Y-Y.

[0035] Figure 7 is a schematic diagram of an application circuit for an integrated planar magnetic incorporating aspects of the disclosed embodiments.

[0036] Figures 8-11 illustrate exemplary implementations of the integrated planar magnetic of the disclosed embodiments extended to matrix magnetics with different core shapes and winding connections.

[0037] DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

[0038] Figure 1 illustrates a schematic diagram of an exemplary integrated planar magnetic 100 incorporating aspects of the disclosed embodiments. The integrated planar magnetic 100 of the disclosed embodiments is generally configured for high power density and high efficiency regulated resonant converters. One turn, secondary side windings, are separated into two groups, each with a one-turn inductor. Vertical windings are implemented to the one-turn inductor to reduce inductor winding loss. The integrated planar converter 100 has a high-power density due to the small footprint given by the one-turn resonant inductor. The resonant inductor is a normal regular inductor, not created by leakage, and can give a relatively small Lm / Lr ratio for the closed-loop regulation of a wide range input voltage DC / DC resonant converter.

[0039] As illustrated in the example of Figure 1, in one embodiment, the integrated planar magnetic 100 of the disclosed embodiments includes three middle legs in the core 108. One leg is for the transformer core 102, while the other two legs are for the resonant inductors, namely a first resonant inductor core 104 and a second resonant inductor core 106. The first resonant inductor core 104 and the second resonant conductor core 106 are integrated with the transformer core 102. The integrated planar magnetic 100 of the disclosed embodiments has a smaller footprint than existing solutions.

[0040] In the example of Figure 1, the integrated planar magnetic 100 includes a primary winding structure 110 and a secondary winding structure 112. In one embodiment, the primary winding structure 110, or primary windings, are multiple layers of planar windings. For example, the primary winding structure 110 can comprise multiple printed circuit board (PCB) layers in series.

[0041] In one embodiment, the secondary windings, also referred to herein as secondary winding structure 112, are separated into two groups. Referring also to Figures 2A, 2C, 3 and 4, the secondary winding structure 112 is separated into a first group 202 and a second group 204.

[0042] As will be discussed further below, the first group 202 and the second group 204 have a one- turn resonant inductor connected in series. In one embodiment, vertical windings are implemented on the one-turn resonant inductor cores 104, 106, and vertical windings are applied on the one turn secondary windings of the transformer core 102.

[0043] As illustrated in Figure 2 A, the first group 202 of secondary windings includes a first plurality 302 of planar windings, a first single turn winding 114 and a second single turn winding 124. The first plurality 302 of planar windings is applied to the transformer core 102 and the first resonant inductor core 104. The first single turn winding 114 is applied to the transformer core 102. The second single turn winding 124 is applied to the first resonant inductor core 104. As shown in the examples of Figures 1 and 2A, the resonant inductor is a one-turn secondary side inductor with a vertical winding. Vertical windings can be used to redistribute the current across the core, which enable lower current density and lower power loss. A vertical winding can also be implemented to the transformer core 102 to reduce the winding loss caused by the magnetizing current. When there is no load current, the transformer acts like an inductor with magnetizing inductance. Even though the excitation current is on the primary side, eddy current is induced in both primary windings and secondary windings. For high frequency step-down DC / DC resonant converters, since multiple secondary layers are in parallel as one-turn, it is easier to implement the vertical winding on the secondary windings than on the primary windings.

[0044] In the example of Figures 1 and 2A, the first single turn winding 114 and the second single turn winding 124 comprise vertical windings. In one embodiment, the first single turn winding 114 and the second single turn winding 124 are connected in series.

[0045] Referring to Figure 2C, in one embodiment, the second group 204 of secondary windings includes a second plurality of planar windings 304, a third single turn winding 116 and a fourth single turn winding 126. As shown in Figure 2C for example, the second plurality of planar windings 304 are applied to the transformer core 102 and the second resonant inductor core 106. The third single turn winding 116 is applied to the transformer core 102, while a fourth single turn winding 126 is applied to the second resonant inductor core 106.

[0046] Similar to the example of Figure 2A, in the example of Figure 2C, the third single turn winding 116 and the fourth single turn winding 126 are vertical windings. In one embodiment, the third single turn winding 116 and the fourth single turn winding 126 are connected in series.

[0047] Figure 5 is a cross-sectional view of the integrated planar magnetic 100 of Figure 1, taken along the line X-X. In this example, the vertical winding implementation on a sixteen (16) layer 8:1 planar transformer is illustrated.

[0048] Figure 6 is a cross-sectional view of the integrated planar magnetic 100 of Figure 1, taken along the line Y-Y. In this example, the cross-section is of a sixteen (16) layer, one (1) turn planar inductor with axis symmetry. In practice, the inductor current will be concentrated on the edges, for example, near the middle leg 104 A with airgaps 128, 130, for the first resonant inductor 104. A similar arrangement is illustrated for the middle leg 106A of the first resonant inductor 106. The vertical windings 124, 126 improve the current density distribution, i.e., lower winding loss. A narrower winding in the horizontal direction has little impact on the winding loss. Winding loss is reduced and efficiency is improved.

[0049] While the aspects of the disclosed embodiments are generally described herein with respect to a one-turn inductor and a one-turn secondary winding transformer to illustrate the impact of the vertical winding on winding loss reduction, the aspects of the disclosed embodiments are not so limited. The aspects of the disclosed embodiments can be extended to multiple turn inductors and multiple turn secondary winding transformers. The one-turn winding is generally easier to implement by copper plating, as developed in printed circuit board (PCB) manufacturing and assembly.

[0050] The integrated planar magnetic 100 of the disclosed embodiments provide an up-down structure, as is illustrated in Figures 5 and 6. For example, as shown in Figure 5, the primary windings 110 are interleaved between the first plurality of planar windings 302 of the first group 202 of secondary windings and the second plurality of planar windings 304 of the second group 204 of secondary windings. The up-down winding structure for the integrated planar magnetic 100 of the disclosed embodiments, rather than a left-right structure, has a higher power density due to the higher integration and the higher efficiency of the vertical windings.

[0051] The aspects of the disclosed embodiments can be applied to matrix magnetics with different core shapes and winding connections. Figures 7-11 illustrate examples of possible implementations.

[0052] In the example of Figure 7, an exemplary application circuit 700 for an integrated planar magnetic 100 of the disclosed embodiments is illustrated. In this example, the transformer turns ratio is 8: 1. The primary windings 110 and the secondary windings 202, 204, from the example of Figures 2A-2C, have eight (8) layers, respectively. The mechanical structure of the integrated planar magnetic for the exemplary application circuit 700 is the same as that shown in Figure 1. There are three middle legs. One leg 102 for the transformer core and two legs or cores 104, 106 for the resonant inductors. The winding structure for the application circuit 700 will be similar to that shown in the examples of Figures 2A-2C. The primary windings 110 include eight (8) layers in series. The secondary windings will also have eight (8) layers. According to the aspects of the disclosed embodiments, the secondary windings are separated into two groups, namely the first group 202 and the second group 204. The first group 202 will have four (4) layers in parallel connected to a one-turn resonant inductor 224 and the second group 204 will have four (4) layers in parallel connected to a one-turn resonant inductor 226. Vertical windings are implemented on the one-turn resonant inductors 224, 226 and the two groups 302, 304 of secondary windings of the transformer 102. An example of this is shown in Figure 6, where there are four layers of planar windings 302 and four layers of planar windings 304.

[0053] Figure 8 illustrates an exemplary implementation with at least a second integrated planer magnetic 800 disposed adjacent to the integrated planar magnetic 100. The structure and arrangement of the integrated planar magnetic 800 is similar to the structure and arrangement of the integrated planar magnetic 100 described herein.

[0054] In the example of Figure 8, the second integrated planar magnetic 800 includes at least one second transformer core 802 with a third resonant inductor core 804 and a fourth resonant inductor core 806. The at least one second transformer core 802 is disposed adjacent to the transformer core 102. The third resonant inductor core 804 and the fourth resonant conductor core 806 are integrated with the at least one second transformer core 802.

[0055] In one embodiment, a second primary winding structure 810 of the at least one second transformer core 802 comprises multiple layers of planar windings connected in series. A second secondary winding structure 812 of the transformer core 802 comprises a third group of secondary windings and a fourth group of secondary windings.

[0056] In one embodiment, the third group of secondary windings includes a third plurality of planar windings 824 applied to the transformer core 802 and the third resonant inductor core 804. A fifth single turn winding 826 is applied to the transformer core 802 and a sixth single turn winding 828 is applied to the third resonant inductor core 804.

[0057] In one embodiment, the fourth group of secondary windings includes a fourth plurality of planar windings 830 applied to the transformer core 802 and the fourth resonant inductor core 806. A seventh single turn winding 832 is applied to the transformer core 802. An eighth single turn winding 834 is applied to the fourth resonant inductor core 804.

[0058] In an embodiment where the turn ratio is desired to be 8:1, since two element transformers 102, 802 are used, the turn ratio for each transformer 102, 802 will be 4:1. The primary and secondary will have 4 layers each, resulting in a total of eight (8) layers. Compared to the example shown in Figure 1, the example of Figure 8 will have a lower component height since less PCB layers are used. However, due to the larger number of legs, the footprint will be larger.

[0059] The aspects of the disclosed embodiments can be extended to a magnetic core with three or more transformer middle legs. When there are two or more transformer middle legs in the magnetic core, the connection between the resonant inductor windings and transformer windings gets more flexibility.

[0060] In the example of Figure 9 and 10, the shapes of the resonant inductor cores 904, 906, 1004, 1006 illustrate the use of different geometrical shapes. The aspects of the disclosed embodiments are not intended to be limited to any particular shape of the legs or cores 102, 104 and 106. Generally, the cores 102, 104 and 106 can have any suitable geometric shape.

[0061] In the example of Figure 11, the resonant inductor core 1106 is connected to the transformer core 102 by the secondary windings in the up side four (4) layers and the resonant inductor core 104 is connected to the transformer core 1102 by the secondary windings in the down side 4 layers. The cross-connection increases winding loss but optimizes the inductor core loss.

[0062] The aspects of the disclosed embodiments lead to at least the following benefits. The proposed invention leads to the following benefits. First, the resonant inductor is a normal regular inductor, compared with the resonant inductor created by leakage, it can have theoretically any inductance values without a significant impact on its power loss. The proposed design suits for the closed-loop regulated wide range input voltage DC / DC resonant converters. Second, the resonant inductor of the disclosed embodiments is a one-turn secondary inductor which has small footprint, i.e., high power density. Third, a vertical winding is applied to the one-turn inductor and secondary windings of the transformer to reduce the winding loss significantly, i.e., high efficiency. In summary, the integrated planar magnetic of the disclosed embodiments has high power density, has high efficiency, and is suitable for the closed-loop regulated wide- range-input DC / DC resonant converters.

[0063] Thus, while there have been shown, described, and pointed out, fundamental novel features of the invention as applied to the exemplary embodiments thereof, it will be understood that various omissions, substitutions and changes in the form and details of devices and methods illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit and scope of the presently disclosed invention. Further, it is expressly intended that all combinations of those elements, which perform substantially the same function in substantially the same way to achieve the same results, are within the scope of the invention.

[0064] Moreover, it should be recognized that structures and / or elements shown and / or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Claims

CLAIMS1. An integrated planar magnetic (100) comprising: a transformer core (102); a first resonant inductor core (104); and a second resonant inductor core (106); wherein the first resonant inductor core (104) and the second resonant conductor core (106) are integrated with the transformer core (102).

2. The integrated planar magnetic (100) according to claim 1, wherein: a primary winding structure (110) of the transformer core (102) comprises multiple layers of planar windings connected in series; and a secondary winding structure (112) of the transformer core (102) comprises a first group (202) of secondary windings and a second group (204) of secondary windings.

3. The integrated planar magnetic (100) according to claim 2, wherein the first group (202) of secondary windings comprises: a first plurality of planar windings (302) applied to the transformer core (102) and the first resonant inductor core (104); a first single turn winding (114) applied to the transformer core (102); and a second single turn winding (124) applied to the first resonant inductor core (104).

4. The integrated planar magnetic (100) according to claim 3, wherein the first single turn winding (114) is a vertical winding.

5. The integrated planar magnetic (100) according to any one of claims 3 or 4, wherein the second single turn winding (124) is a vertical winding.

6. The integrated planar magnetic (100) according to any one of claims 3 to 5, wherein the first single turn winding (114) and the second single turn winding (124) are connected in series.

7. The integrated planar magnetic (100) according to any one of claims 2 to 6, wherein the second group (204) of secondary windings comprises: a second plurality of planar windings (304) applied to the transformer core (102) and the second resonant inductor core (106);a third single turn winding (116) applied to the transformer core (102); and a fourth single turn winding (126) applied to the second resonant inductor core (106).

8. The integrated planar magnetic (100) according to claim 7, wherein the third single turn winding (116) comprises a vertical winding.

9. The integrated planar magnetic (100) according to any one of claims 7 or 8, wherein the fourth single turn winding (126) comprises a vertical winding.

10. The integrated planar magnetic (100) according to any one of claims 7 to 9, wherein the third single turn winding (116) and the fourth single turn winding (126) are connected in series.

11. The integrated planar magnetic (100) according to any one of claims 2 to 10, wherein: the first single turn winding (114) and the second single turn winding (124) of the first group (202) of secondary windings are connected to the first plurality of planar windings (302): and the third single turn winding (116) and the fourth single turn winding (126) of the second group (204) of secondary windings are connected to the second plurality of planar windings (304).

12. The integrated planar magnetic (100) according to any one of claims 2-11 wherein the primary winding structure (110), the first group (202) of secondary windings and the second group (204) of secondary windings are arranged in an up-down structure.

13. The integrated planar magnetic (100) according to any one of the preceding claims further comprising at least one second transformer core (802) with a third resonant inductor core (804) and a fourth resonant inductor core (806), being disposed adjacent to the transformer core (102), wherein the third resonant inductor core (804) and the fourth resonant conductor core (806) are integrated with the at least one second transformer core (802).

14. The integrated planar magnetic (100) according to claim 13, wherein: a second primary winding structure (810) of the at least one second transformer core (802) comprises multiple layers of planar windings connected in series; anda second secondary winding structure (812) of the transformer core (802) comprises a third group of secondary windings and a fourth group of secondary windings.

15. The integrated planar magnetic (100) according to claim 14, wherein the third group of secondary windings comprises: a third plurality of planar windings (824) applied to the transformer core (802) and the third resonant inductor core (804); a fifth single turn winding (826) applied to the transformer core (802); and a sixth single turn winding (828) applied to the third resonant inductor core (804); and the fourth group of secondary windings comprises: a fourth plurality of planar windings (830) applied to the transformer core (802) and the fourth resonant inductor core (806); a seventh single turn winding (832) applied to the transformer core (802); and an eighth single turn winding (834) applied to the fourth resonant inductor core ( 806).

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