A completely symmetrical new vertical structure point of load module

Abstract

The application discloses a novel completely symmetrical vertical structure load point module, and relates to the technical field of power electronics, comprising a gallium nitride power module, a magnetic core, a winding, a plurality of printed circuit boards and an output capacitor, the magnetic core comprises an upper end plate, a lower end plate and a plurality of legs between the two, the plurality of printed circuit boards comprise a first, a second and a third printed circuit board; wherein the first printed circuit board integrated with the gallium nitride power module is located on the side of the upper end plate away from the lower end plate, the second printed circuit board comprises a plurality of openings corresponding to the legs and is embedded between the upper end plate and the lower end plate through the openings, the winding is sleeved on at least part of the legs and is connected to the second printed circuit board, and the third printed circuit board integrated with the output capacitor is located on the side of the lower end plate away from the upper end plate. Since the manufacturing material of the magnetic core comprises an alloy powder core, the interference on active devices can be reduced, the heavy load loss can be reduced, the power density can be improved, and the heat dissipation of the gallium nitride device is also facilitated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power electronics, and particularly relates to a novel completely symmetrical vertical structure point-of-load module. BACKGROUND

[0002] Advanced processors have driven the rapid development of artificial intelligence, cloud computing and the digital economy. At present, these processors CPU adopts 7 nanometer, 5 nanometer silicon process, and rapidly advances to 3 nanometer. The rated core working voltage of these advanced process CPUs is generally 0.75V-0.85V, and in order to achieve the required performance workload, the rated current also needs to be greatly increased. It can be seen that the reduction of voltage and the increase of current bring challenges to POL (Point-Of-Load), and the future high-performance processor needs a high-efficiency and high-power-density POL converter to support hundreds of amperes of current under extremely low voltage (i.e. <1V). In addition, the increase of current will also exacerbate the loss of the mainboard PCB copper path, and bring a large amount of additional heat to the processor thermal management system; at the same time, the voltage drop on the PCB copper path is proportional to the increase of current, and the sharp increase of current will lead to the drop of the core voltage obtained by the CPU, and this voltage drop effect will have a great impact on the performance of the processor.

[0003] Figure 1 is a schematic diagram of transverse power supply in the related art. In the prior art, the POL converter is mostly used Figure 1 The POL converter is located beside the mainboard processor, and the current flows into the processor from the POL converter in the transverse direction. In this way, inherent PCB copper path loss is generated, and it is unavoidable no matter how close the POL converter is to the processor core.

[0004] Figure 2 is a schematic diagram of vertical power supply in the related art. In order to solve the line loss caused by the PCB copper path, there is also a Figure 2 The POL converter is arranged opposite to the mainboard processor in the vertical direction. The first POL module with vertical structure has been developed by Princeton University in the United States, but the magnetic core thereof is a ferrite material, and needs to be opened to prevent saturation, which will cause the increase of magnetic field leakage and serious edge loss, resulting in low heavy load efficiency. SUMMARY

[0005] In order to solve the above problems in the prior art, the application provides a novel completely symmetrical vertical structure point-of-load module. The technical problems to be solved by the application are solved through the following technical scheme:

[0006] The application provides a novel full-symmetrical vertical-structure load point module, comprising a gallium nitride power module, a magnetic core, a winding, a plurality of printed circuit boards and an output capacitor, the magnetic core comprises an upper end plate, a lower end plate and a plurality of legs between the upper end plate and the lower end plate, the plurality of printed circuit boards comprise a first printed circuit board, a second printed circuit board and a third printed circuit board, wherein,

[0007] The first printed circuit board is located on the side of the upper end plate away from the lower end plate and integrates the gallium nitride power module, the second printed circuit board comprises a plurality of openings corresponding to the legs and is embedded between the upper end plate and the lower end plate through the openings, the winding is sleeved on at least part of the legs and connected to the second printed circuit board, and the third printed circuit board is located on the side of the lower end plate away from the upper end plate and integrates the output capacitor.

[0008] In an embodiment of the application, the gallium nitride power module comprises an active integrated four-phase GaN device half-bridge circuit, a driver and a decoupling capacitor.

[0009] In an embodiment of the application, the orthographic projections of the upper end plate and the lower end plate are both squares in the direction perpendicular to the plane where the upper end plate is located, and the orthographic projections of the plurality of legs are arranged along the circumference of the square.

[0010] In an embodiment of the application, the plurality of legs comprise four first legs and four second legs, wherein the orthographic projections of the four first legs are respectively located at the vertices of the square, and a second leg is arranged between any two adjacent first legs.

[0011] In an embodiment of the application, the winding comprises a four-phase winding, and the four-phase winding is sleeved on the four second legs.

[0012] In an embodiment of the application, the material of the magnetic core comprises an alloy powder core.

[0013] In an embodiment of the application, the first printed circuit board, the second printed circuit board and the third printed circuit board are electrically connected through copper pillars.

[0014] In an embodiment of the application, the four-phase GaN device half-bridge circuit comprises a capacitor C o , a resistor R L , transistors S1, S2, S3, S4, S5, S6, S7 and S8, wherein,

[0015] the drain of S1, S3, S5 and S7 is connected to the positive terminal of an input voltage V in , the source of S1, S3, S5 and S7 is respectively connected to the drain of S2, S4, S6 and S8, and the source of S2, S4, S6 and S8 is connected to the negative terminal of the input voltage Vin The negative end of the winding is connected, and the source of S1, S3, S5 and S7 and the drain of S2, S4, S6 and S8 include nodes N1, N2, N3 and N4 respectively. One end of the four-phase winding is connected to the nodes N1, N2, N3 and N4 respectively, and the other end is connected to the capacitor C o Connect to input voltage V in The negative terminal of the resistor R L With capacitor C o in parallel.

[0016] In one embodiment of the present invention, the four-phase GaN device half-bridge circuit is centrally symmetrical about the center point of the square on the first printed circuit board.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] An embodiment of the present invention provides a novel, fully symmetrical vertical structure point-of-load module, comprising a gallium nitride power module, a magnetic core, windings, multiple printed circuit boards, and output capacitors. The magnetic core is made of an alloy powder core, which reduces interference with active devices, lowers heavy-load losses, increases power density, reduces CPU trace losses, and facilitates heat dissipation from the gallium nitride device.

[0019] In addition, the four-phase GaN device half-bridge circuit used in the present invention is completely symmetrical and can achieve four-phase buck current sharing. The three printed circuit boards are electrically connected through copper pillars, which can assist in dissipating heat from the magnetic core while shielding leakage magnetic interference.

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of lateral power supply in the related art;

[0022] Figure 2 It is a schematic diagram of vertical power supply in related art;

[0023] Figure 3 This is a structural diagram of a completely symmetrical new vertical structure load point module provided by an embodiment of the present invention;

[0024] Figure 4 This is a structural schematic diagram of a magnetic core provided by an embodiment of the present invention;

[0025] Figure 5 Schematic diagram of a four-phase GaN device half-bridge circuit provided by an embodiment of the present invention;

[0026] Figure 6a This is the voltage oscillation waveform of a traditional ferrite core;

[0027] Figure 6b is a voltage oscillation waveform diagram of a magnetic core provided by an embodiment of the present application;

[0028] Figure 7 is a parasitic inductance of a circuit in which different magnetic cores are located provided by an embodiment of the present application;

[0029] Figure 8a is a thermal performance simulation result diagram of a ferrite magnetic plate provided by an embodiment of the present application;

[0030] Figure 8b is a thermal performance simulation result diagram of an alloy material magnetic plate provided by an embodiment of the present application;

[0031] Figure 8c is a thermal performance simulation result diagram of a ferrite magnetic plate with legs provided by an embodiment of the present application;

[0032] Figure 8d is a thermal performance simulation result diagram of an alloy magnetic plate with legs provided by an embodiment of the present application;

[0033] Figure 8e is a thermal performance simulation result diagram of a ferrite magnetic core provided by an embodiment of the present application;

[0034] Figure 8f is a thermal performance simulation result diagram of an alloy magnetic core provided by an embodiment of the present application. DETAILED DESCRIPTION

[0035] The present application will be further described below in conjunction with specific embodiments, but the embodiments of the present application are not limited thereto.

[0036] Figure 3 is a structural schematic diagram of a completely symmetrical new vertical structure load point module provided by an embodiment of the present application, Figure 4 is a structural schematic diagram of a magnetic core provided by an embodiment of the present application. As shown in Figures 3-4 the present application provides a completely symmetrical new vertical structure load point module, which comprises a gallium nitride power module 1, a magnetic core 2, a winding 3, a plurality of printed circuit boards 4 and an output capacitor (not shown in the figure), the magnetic core 2 comprises an upper end plate 201, a lower end plate 202 and a plurality of legs 5 located between the upper end plate 201 and the lower end plate 202, the plurality of printed circuit boards 4 comprises a first printed circuit board 401, a second printed circuit board 402 and a third printed circuit board 403; wherein,

[0037] The first printed circuit board 401 is located on the side of the upper end plate 201 away from the lower end plate 202 and is integrated with the gallium nitride power module 1. The second printed circuit board 402 includes multiple openings corresponding to the legs 5 and is embedded between the upper end plate 201 and the lower end plate 202 through the openings. The winding 3 is mounted on at least part of the legs 5 and connected to the second printed circuit board 402. The third printed circuit board 403 is located on the side of the lower end plate 202 away from the upper end plate 201 and is integrated with the output capacitor.

[0038] The vertical structure point-of-load module provided in this embodiment includes an active integrated portion and a passive integrated portion, wherein the active integrated portion includes a gallium nitride power module 1. It should be understood that parasitic inductance will reduce the reliability of gallium nitride devices, and parasitic capacitance will slow down the switching speed of gallium nitride devices, causing gallium nitride devices to lose their switching speed advantage. Therefore, this embodiment integrates four half-bridge circuits, a driver, and decoupling capacitors into the gallium nitride power module 1 through active integration to minimize key parasitic parameters. Optionally, the gallium nitride device is an EPC2023. The parasitic parameters within the EPC2023 are very small. It uses an LGA or BGA package, but compared with silicon-based packages, it is essentially a bare chip.

[0039] Furthermore, the passive integrated part is Figure 4 The magnetic core 2 shown in FIG. 2 includes, in particular, an upper end plate 201, a plurality of legs 5 and a lower end plate 202. Figure 3 From the perspective shown, the first printed circuit board 401 integrated with the gallium nitride power module 1 is located on the top of the magnetic core 2, the third printed circuit board 403 integrated with the output capacitor is located at the bottom of the magnetic core 2, and the second printed circuit board 402 includes openings corresponding to the multiple legs 5, so that it can be embedded between the upper end plate 201 and the lower end plate 202 for connection to the winding 3 sleeved on at least some of the legs 5.

[0040] Exemplarily, the gallium nitride power module 1 includes an actively integrated four-phase GaN device half-bridge circuit, a driver, and a decoupling capacitor.

[0041] Figure 5 This is a schematic diagram of a four-phase GaN device half-bridge circuit provided by an embodiment of the present invention. Figure 5 , the four-phase GaN device half-bridge circuit includes capacitor C o , resistor R L , transistors: S1, S2, S3, S4, S5, S6, S7 and S8; among them,

[0042] The drain of S1, S3, S5 and S7 is connected to the input voltage V in The positive terminal of S1, S3, S5 and S7 are connected to the drain of S2, S4, S6 and S8 respectively, and the source of S2, S4, S6 and S8 is connected to the input voltage VThe negative end of the input voltage V in , the source of S1, S3, S5 and S7 is connected with the drain of S2, S4, S6 and S8 respectively, and the node N1, N2, N3 and N4 are included between them, one end of the four-phase winding 3 is connected with the node N1, N2, N3 and N4 respectively, and the other end is connected with the capacitor C o connected to the negative end of the input voltage V in , the resistance R L is connected in parallel with the capacitor C o .

[0043] Specifically, the voltage equation of the four-phase inductor is expressed as:

[0044]

[0045] In the formula, v1, v2, v3 and v4 represent the voltage across the four-phase inductor, i1, i2, i3 and i4 represent the current through the four-phase inductor, L1, L2, L3, L4 are the self-inductance of the four-phase inductor, M ij (i = 1, 2, 3, j = 2, 3, 4) is the mutual inductance between the four-phase inductors, M ij <0.

[0046] The above-mentioned transistors are all gallium nitride transistors, and the gallium nitride device has higher switching frequency and higher power density.

[0047] Optionally, in combination with Figures 3-4 , the orthogonal projection of the upper end plate 201 and the lower end plate 202 in the direction perpendicular to the plane where the upper end plate 201 is located is a square, and the orthogonal projection of the plurality of legs 5 is arranged along the circumference of the square.

[0048] It should be noted that in the embodiment, the orthogonal projection of the upper end plate 201 and the lower end plate 202 in the direction perpendicular to the plane where the upper end plate 201 is located is a square and coincides with the center point of the square, and when the four-phase GaN device half-bridge circuit is integrated on the first printed circuit board 401, it is centered symmetrically about the center point of the square. The embodiment can effectively reduce the imbalance between the four-phase currents by completely symmetrically arranging the four-phase GaN device half-bridge circuit.

[0049] Please continue to refer to Figure 4 , in the above-mentioned completely symmetrical new vertical structure load point module, the plurality of legs 5 of the magnetic core 2 include four first legs 501 and four second legs 502, wherein the orthogonal projection of the four first legs 501 is respectively located at the vertex of the square, and the second leg 502 is arranged between the adjacent two first legs 501.

[0050] In addition, the completely symmetrical new vertical structure load point module includes a four-phase winding 3, and the four-phase winding 3 is sleeved on the four second legs 502 respectively.

[0051] In this embodiment, eight legs 5 are provided between the upper end plate 201 and the lower end plate 202. The eight legs 5 are arranged along the circumference of the square, four of which are first legs 501 and the other four are second legs 502. As shown in the figure, the positive projections of the four first legs 501 are respectively located at the vertices of the square, and a second leg 502 is provided between two adjacent first legs 501. This structure including eight legs 5 can achieve complete symmetry, and the four-phase windings 3 are respectively sleeved on the four second legs 502.

[0052] It should be understood that in this embodiment, if the first legs 501 are not provided at the four vertices of the square, then for any second leg 502 connected with the winding 3, the magnetic flux generated will flow toward the other second legs 502, thereby forming full coupling. Therefore, in this embodiment, the coupling coefficient can be adjusted by introducing four first legs 501 so that the coupling coefficient is not equal to 1, that is, full coupling is avoided, thereby achieving the same inductance parameters.

[0053] In addition, in the above-mentioned completely symmetrical new vertical structure load point module, the material used to make the magnetic core 2 includes an alloy powder core. In the related art, the magnetic core 2 is mostly made of ferrite material, but the saturation magnetic flux density of ferrite material is low, and generally an additional air gap is required to prevent saturation, which in turn leads to increased magnetic field leakage and serious edge loss, resulting in low overload efficiency. In order to avoid the above problems, the present invention uses an alloy powder core to make the magnetic core 2. On the one hand, the alloy powder core can reduce interference with active devices. On the other hand, the alloy powder core is a soft magnetic material with a distributed air gap and a high magnetic saturation density. Therefore, there is no need to open an additional air gap, which can avoid problems such as increased magnetic field leakage and edge loss. Therefore, in theory, the vertical structure load point module provided by the present invention has a higher overload efficiency.

[0054] Furthermore, if Figure 3 As shown, in this embodiment, the first printed circuit board 401, the second printed circuit board 402, and the third printed circuit board 403 are electrically connected via copper pillars 6. The copper pillars 6 also assist in dissipating heat from the magnetic core 2 while shielding against magnetic flux leakage interference. As can be seen, the magnetic core 2 of the present invention has a simple structure, is easy to produce, and is commercially viable.

[0055] Next, the completely symmetrical novel vertical structure load point module provided by the present invention will be further described through simulation experiments.

[0056] GaN devices inherently switch extremely quickly and are very sensitive to parasitic parameters such as parasitic inductance. Even small parasitic inductance can cause large voltage spikes and resonances in the circuit. Traditional ferrite cores have high permeability, which significantly increases parasitic inductance in active circuits, affecting power and drive loops. Compared to traditional ferrite materials, the new cores have lower permeability and a uniformly distributed air gap, which suppresses the radiation of the magnetic field into the surrounding environment and reduces electromagnetic interference with active circuits.

[0057] Figure 6a is a voltage oscillation waveform diagram of a traditional ferrite core, Figure 6b is a voltage oscillation waveform diagram of a magnetic core provided by an embodiment of the present application. Obviously, as Figures 6a-6b indicated, the voltage oscillation amplitude of the alloy powder core magnetic core prototype is obviously smaller than that of the traditional ferrite magnetic core prototype. Figure 7 is the parasitic inductance of a circuit in which different magnetic cores are located. It can be seen that, compared with the traditional ferrite core, the parasitic inductance generated by using the alloy powder core is reduced by about 0.01 nH per phase. Experiments prove that the alloy powder core is helpful for reducing the parasitic inductance caused by electromagnetic interference.

[0058] It should be understood that, since the thermal conductivity coefficient of the ferrite material is low (1-5 W / mK), and the temperature rises due to the core loss, the traditional 3D integrated load point module also has the problem of poor heat dissipation performance. In the present application, the alloy powder core has higher thermal conductivity (>5 W / mK) and lower core loss than the ferrite. In addition, the proposed magnetic core is also beneficial to the heat dissipation of the GaN device and module. The eight legs thereof can be regarded as "heat sink fins", which increase the heat dissipation area of air and reduce the thermal resistance.

[0059] Based on the magnetic core structure provided by the present application, ferrite and alloy materials are simulated by using ANSYS Icepak software. Figure 8a is a thermal performance simulation result diagram of a ferrite magnetic plate provided by an embodiment of the present application, Figure 8b is a thermal performance simulation result diagram of an alloy material magnetic plate provided by an embodiment of the present application, as Figures 8a-8b indicated, the overall temperature of the GaN device with the magnetic plate made of the alloy material is 1℃ lower than that of the GaN device with the ferrite magnetic plate, which improves the thermal performance to a certain extent.

[0060] Figure 8c is a thermal performance simulation result diagram of a ferrite magnetic plate with legs provided by an embodiment of the present application, Figure 8d is a thermal performance simulation result diagram of an alloy magnetic plate with legs provided by an embodiment of the present application. Compared with Figure 8a , 8b , Figure 8c , 8d the overall temperature is significantly reduced by 23℃, which indicates that the legs proposed in the present application not only can be used as winding inductors, but also can greatly improve the heat dissipation performance.

[0061] It should be noted that, Figure 8a , 8b8c and 8d are thermal simulation results in an ideal case, i.e., without considering the magnetic core loss, the magnetic core loss of the alloy material and the ferrite material can be extracted by experiment under no-load conditions, and are 0.8495 W and 1.32 W, respectively.

[0062] Figure 8e is a thermal performance simulation result diagram of a ferrite magnetic core provided by an embodiment of the present application, Figure 8f is a thermal performance simulation result diagram of an alloy magnetic core provided by an embodiment of the present application. Figures 8e-8f As shown in the figure, the temperature of the GaN device is increased by 13-15 DEG C compared with Figure 8c , 8d However, since the alloy magnetic core has higher thermal conductivity and lower magnetic core loss, the alloy magnetic core is still about 5 DEG C lower than the ferrite magnetic core. Compared with other three-dimensional integrated modules, the magnetic structure based on the alloy powder core can significantly improve the thermal performance of the three-dimensional vertical load point module.

[0063] From the above embodiments, the beneficial effects of the present application are as follows:

[0064] An embodiment of the present application provides a novel vertical structure load point module completely symmetrical, comprising: a gallium nitride power module, a magnetic core, a winding, a plurality of printed circuit boards and an output capacitor, wherein the manufacturing material of the magnetic core comprises an alloy powder core, so that the interference to the active device can be reduced, the heavy load loss can be reduced, the power density can be improved, the CPU trace loss can be reduced, and the heat dissipation of the gallium nitride device is also beneficial.

[0065] In addition, the four-phase GaN device half-bridge circuit adopted by the present application is completely symmetrical, can realize four-phase buck current sharing, three printed circuit boards are electrically connected through copper columns, and the copper columns can assist the heat dissipation of the magnetic core and shield the leakage magnetic interference.

[0066] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0067] In addition, the terms "first", "second", etc. are used only for descriptive purposes and do not connote or imply relative importance of the indicated elements or an implied sequence of the described operations. Thus, features defined with "first", "second" or the like can include one or more of either the described features let alone one or more other features. In the description of the present application, the meaning of "a plurality" is two or more, unless expressly specified otherwise.

[0068] Reference to terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that a particular feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. The illustrative appearances of the above-mentioned terms in various places in the specification are not necessarily referred to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Also, the description of a particular feature, structure, material, or characteristic in relation to an embodiment or example does not indicate that it is necessarily included in all embodiments or examples. The various illustrative embodiments described in this specification can be combined in any suitable manner.

[0069] Although the present application has been described herein in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art upon reviewing the present application's description. It is therefore a feature of the present application to

[0070] The above description is further to be understood that not all of the components of the present application are required in every embodiment of the present application. The above description is further to be understood that not all of the components of the present application are required in every embodiment of the present application.

Claims

1. A novel fully symmetrical vertical structure point of load module characterized in that, The application relates to a gallium nitride power module, a magnetic core, a winding, a plurality of printed circuit boards and an output capacitor, the magnetic core comprising an upper end plate, a lower end plate and a plurality of legs between the upper end plate and the lower end plate, the plurality of printed circuit boards comprising a first printed circuit board, a second printed circuit board and a third printed circuit board; wherein, the first printed circuit board is located on a side of the upper end plate away from the lower end plate and integrates the gallium nitride power module, the second printed circuit board comprises a plurality of openings corresponding to the legs and is embedded between the upper end plate and the lower end plate through the openings, the winding is sleeved on at least part of the legs and connected to the second printed circuit board, and the third printed circuit board is located on a side of the lower end plate away from the upper end plate and integrates the output capacitor. The gallium nitride power module comprises an active integrated four-phase GaN device half-bridge circuit, a driver and a decoupling capacitor.

2. The novel fully symmetrical vertical structure LPM of claim 1, wherein, In a direction perpendicular to a plane where the upper end plate is located, the orthographic projections of the upper end plate and the lower end plate are both square, and the orthographic projections of the plurality of legs are arranged along the circumference of the square.

3. The novel fully symmetrical vertical structure LPM of claim 1, wherein, The plurality of legs comprises four first legs and four second legs, wherein the orthographic projections of the four first legs are respectively located at the vertices of the square, and a second leg is arranged between every two adjacent first legs.

4. The novel fully symmetrical vertical structure LPM of claim 3, wherein, The four-phase winding is sleeved on the four second legs.

5. The novel fully symmetrical vertical structure LPM of claim 4, wherein, The manufacturing material of the magnetic core comprises an alloy powder core.

6. The novel fully symmetrical vertical structure LPM of claim 1, wherein, The first printed circuit board, the second printed circuit board and the third printed circuit board are electrically connected through copper columns.

7. The novel fully symmetrical vertical structure LPM of claim 1, wherein, The four-phase GaN device half-bridge circuit is centrosymmetric on the first printed circuit board about the center point of the square.

8. The novel fully symmetrical vertical structure LPM of claim 5, wherein, The four-phase GaN device half-bridge circuit comprises a capacitor C o , a resistor R L , transistors: S1, S2, S3, S4, S5, S6, S7 and S8; wherein, The drain of S1, S3, S5 and S7 is connected to the positive terminal of the input voltage V in , the source of S1, S3, S5 and S7 is connected to the drain of S2, S4, S6 and S8 respectively, the source of S2, S4, S6 and S8 is connected to the negative terminal of the input voltage V in , between the source of S1, S3, S5 and S7 and the drain of S2, S4, S6 and S8 respectively includes nodes N1, N2, N3 and N4 respectively, one end of the four-phase winding is connected to the nodes N1, N2, N3 and N4 respectively, the other end is connected to the negative terminal of the input voltage V o through the capacitor C in , the resistor R L is connected in parallel with the capacitor C o .

9. The fully symmetrical novel vertical structure LPM of claim 8, wherein, ​

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