Isolated dc / dc integrated method based on planar wireless energy transfer coil

Abstract

This invention discloses an integrated isolated DC / DC converter based on a planar wireless power transfer coil. It employs a core-separated planar helical coil structure, including a primary coil and a secondary coil, with a magnetic core positioned on the back of each coil. A spacer is placed between the magnetic core and the coil. The secondary and primary coils are respectively embedded in the upper and lower layers of an H-shaped solid insulation structure. A water-cooling plate is positioned on the back of each magnetic core, and secondary and primary power modules are respectively positioned on the back of the upper and lower water-cooling plates, configuring the isolated DC / DC topology parameters. This invention's integrated isolated DC / DC converter based on a planar wireless power transfer coil integrates the planar wireless power transfer coil and power circuit design, balancing power density, insulation capability, and efficiency.

Description

Technical Field

[0001] This invention belongs to the field of power electronics and electromagnetic devices technology, specifically relating to an integrated method for isolated DC / DC converters based on planar wireless power transfer coils. Background Technology

[0002] With the increasing demand for high-power-density power conversion equipment in scenarios such as data centers, new energy DC aggregation, and electric transportation, solid-state transformers (SSTs) have attracted attention due to their advantages such as multi-port functionality, reconfigurability, and power controllability. SST isolation stages typically employ medium-frequency / high-frequency isolation transformers to achieve electrical isolation and voltage transformation.

[0003] In existing closed-circuit magnetic isolation transformer structures, weak paths for surface discharge exist between the primary and secondary coils and the magnetic core. Under the superimposed stress of medium-voltage power frequency and high dv / dt pulses, the electric field distribution between coils and between coils and the magnetic core exhibits strong non-uniform characteristics, easily leading to partial discharge and insulation aging. In engineering, methods such as thickening the main insulation, increasing the coil spacing, and overall potting are often used to improve withstand voltage and suppress partial discharge. However, these methods occupy window space, reduce coupling, increase leakage inductance and copper loss, and introduce higher thermal resistance and manufacturing costs, limiting the engineering application of SST (Self-Supported Transformer). Summary of the Invention

[0004] The purpose of this invention is to provide an integrated isolated DC / DC converter based on a planar wireless power transfer coil. By separating the magnetic core, H-type main insulation, layered heat dissipation and power module integrated design, it eliminates weak paths of surface discharge, improves insulation withstand voltage and heat dissipation capabilities, and takes into account high power density, high efficiency and high reliability.

[0005] The technical solution of this invention is an integrated isolated DC / DC converter based on a planar wireless power transfer coil, the steps of which are as follows: S1. It adopts a magnetic core-separated planar spiral coil structure, including a primary side coil and a secondary side coil, and a magnetic core is set on the back of the coil, with a spacer between the magnetic core and the coil. S2, the secondary coil, and the primary coil are respectively embedded in the upper and lower layers of the H-type solid insulation structure; S3. Water-cooled plates are installed on the back of the magnetic core. Secondary power modules and primary power modules are installed on the back of the upper and lower water-cooled plates, respectively.

[0006] S4. Configure the parameters of the isolated DC / DC topology.

[0007] The invention is further characterized in that: The primary power module includes a primary inverter and a primary resonant capacitor, and the secondary power module includes a secondary resonant capacitor and a secondary rectifier. The lead wire of the primary coil is connected in series with the primary resonant capacitor and then connected to the primary inverter circuit. The lead wire of the secondary coil is connected in series with the secondary resonant capacitor and then connected to the secondary rectifier.

[0008] Both the primary and secondary coils are planar helical coils wound with Litz wire, and wireless power transmission is achieved through magnetic coupling.

[0009] The H-type solid insulation structure serves as the main insulation between the primary and secondary coils. Its geometric shape limits the electrical clearance and creepage distance, thus suppressing partial discharge.

[0010] The gasket is placed between the magnetic core and the side coil, serving both electrical isolation and low thermal resistance heat conduction functions.

[0011] The gaps between the primary coil, the secondary coil, and the H-type insulation structure are encapsulated with epoxy resin to improve the overall insulation integrity and mechanical strength.

[0012] The water-cooled plate is bonded to the power module and magnetic core to form a vertical heat dissipation path.

[0013] Isolated DC / DC topologies employ CLLC, LLC resonant or non-resonant converters such as DAB topologies.

[0014] The resonant capacitor parameters of the CLLC topology are set according to the matching of the corresponding leakage inductance and resonant angular frequency.

[0015] Another technical solution adopted in this invention is: an isolated DC / DC converter based on a planar wireless power transfer coil, designed using the above-mentioned integrated method for isolated DC / DC converters based on a planar wireless power transfer coil, comprising, from top to bottom, a primary-side power module, a primary-side water-cooled plate, a primary magnetic core, a primary-side gasket, a primary-side coil, an H-shaped solid insulation layer, a secondary-side coil, a secondary-side gasket, a secondary magnetic core, a secondary water-cooled plate, and a secondary-side power module stacked in a planar manner; the primary and secondary coils are planar spiral coils, the H-shaped insulation layer is placed between the coils as the main insulation, and insulating heat-conducting pads and water-cooled plates are provided on the upper and lower sides to achieve integrated isolation, heat dissipation, and power circuitry.

[0016] The beneficial effects of this invention are: The present invention provides an integrated method for isolated DC / DC based on planar wireless power transfer coils. The core of this method is the physical separation of the primary and secondary magnetic cores. Solid main insulation technology is introduced between the primary and secondary sides as a controllable electrical isolation medium. This method eliminates the weak path of surface discharge between the coil and magnetic core of the closed magnetic circuit transformer from a structural perspective, and significantly improves the withstand voltage level and long-term insulation reliability. The design incorporates a planar layered structure, insulating thermal pads, and primary and secondary water-cooled plates to create a low thermal resistance heat dissipation channel, achieving efficient heat dissipation and temperature rise control for power devices, coils, and magnetic cores. The planar wireless power transfer coil-power module integrated design balances power density, insulation capability and efficiency, and solves the problems of insulation breakdown and partial discharge that easily occur in SST isolation transformers under medium voltage power frequency and high dv / dt superimposed stress, while traditional thickened insulation / spacing / potting sacrifice window utilization, coupling and thermal management and increase costs. Attached Figure Description

[0017] Figure 1 This is an integrated schematic diagram of the isolated DC / DC integrated method based on planar wireless power transfer coil of the present invention; Figure 2 This is a diagram of the planar spiral coil structure in the isolated DC / DC integrated method based on the planar wireless power transfer coil of the present invention; Figure 3 This refers to the relative positions of the primary coil, secondary coil, and H-type solid insulation structure in the isolated DC / DC integrated method based on planar wireless power transmission coil of this invention. Figure 4 This invention relates to a CLLC-type isolated DC / DC circuit; Figure 5 This invention relates to an LLC-type isolated DC / DC circuit; Figure 6 This invention relates to the DAB-type non-isolated DC / DC circuit; Figure 7 Typical voltage and current operating waveforms of the isolation converter inverter and secondary rectifier; Figure 8 When the load increases, the output voltage and current of the secondary rectifier change. Detailed Implementation

[0018] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] Example 1 The isolated DC / DC integrated method based on planar wireless power transfer coil of the present invention is implemented according to the following steps: Step 1: As Figure 1 and Figure 2As shown, the isolation transformer structure is designed as a planar spiral coil structure with a magnetic core separation, including a secondary coil and a primary coil arranged symmetrically on the top and bottom. Magnetic cores are laid on the back of both the primary and secondary coils to enhance the coupling effect between the primary and secondary coils. In addition, spacers are added between the primary magnetic core and the primary coil, and between the secondary magnetic core and the secondary coil to establish a low thermal resistance heat conduction path to conduct heat out of the coil.

[0020] Step Two: A solid insulation support structure is used between the primary and secondary coils, with an H-type solid insulation structure as the main insulation. The H-type solid insulation structure is as follows: Figure 3 As shown, the secondary coil and the primary coil are embedded in the upper and lower layers of the H-shaped solid insulation structure, respectively. The H-shaped geometry limits the electrical clearance and creepage distance at critical edges, weakens the field strength at the tip and the weak path along the surface, thereby improving the withstand voltage and insulation reliability and suppressing the development of partial discharge.

[0021] Step 3: Install heat dissipation water-cooling plates on the back of the magnetic core on both the primary and secondary sides to dissipate heat from the magnetic core and coil. Then, the power modules on the primary and secondary sides are respectively attached to the heat dissipation water-cooling plate structures on both sides, achieving integrated heat dissipation of the power modules and the planar transformer.

[0022] Step 4: Configure the topology and parameters of the isolated DC / DC converter based on the planar wireless power transfer coil.

[0023] Example 2 Based on Example 1, the primary power module includes a primary inverter and a primary resonant capacitor, and the secondary power module includes a secondary resonant capacitor and a secondary rectifier. The lead wire of the primary coil is connected in series with the primary resonant capacitor and then connected to the primary inverter circuit. The lead wire of the secondary coil is connected in series with the secondary resonant capacitor and then connected to the secondary rectifier.

[0024] Example 3 Based on Example 2, both the primary and secondary coils are planar helical coils wound with Litz wire, and wireless power transmission is achieved through magnetic coupling.

[0025] After step two is completed, epoxy resin is used to encapsulate the gaps between the primary coil, the secondary coil and the H-type insulation structure to improve the overall insulation and mechanical strength.

[0026] Example 4 Based on Example 3, a gasket is placed between the magnetic core and the side coil, and the gasket is an insulating thermally conductive pad. It has both electrical isolation and low thermal resistance thermal conductivity functions.

[0027] The water-cooled plate is bonded to the power module and magnetic core to form a vertical heat dissipation path.

[0028] Example 5 Based on Example 4, in step 4, the topology typically consists of a bridge inverter, an isolation network, and a bridge rectifier.

[0029] The isolation network of a resonant LLC or CLLC DC / DC converter includes a primary-side resonant capacitor and a primary-side coil, as well as a secondary-side resonant capacitor and a secondary-side coil. The bridge inverter and the resonant capacitor in the isolation network constitute the primary-side power module, and the bridge rectifier and the secondary-side resonant capacitor in the isolation module constitute the secondary-side power module.

[0030] Isolation networks can typically be resonant CLLC or LLC topologies, or non-resonant such as DAB topologies. These three types of topologies are respectively as follows: Figures 4-6 As shown, the primary-side power module corresponds to the primary-side power module in the diagram, and the secondary-side power module corresponds to the secondary-side power module in the diagram. When it is a resonant topology CLLC, its resonant capacitor and its primary-side resonant capacitor values ​​satisfy the following relationship:

[0031] in, ω 0 represents the resonant angular frequency of the DC / DC isolation module. L rp This is represented as the primary leakage inductance of a wireless planar coil transformer.

[0032] The value of the secondary resonant capacitor satisfies the following relationship:

[0033] In the formula, L rs This is represented as the secondary leakage inductance of a wireless planar coil transformer.

[0034] When it is a resonant topology LLC, its primary-side capacitance parameters satisfy:

[0035] In the formula, L rp1 This is expressed as the first-order side leakage inductance value of the LLC converter under the Γ model.

[0036] Example 6 The isolated DC / DC converter based on a planar wireless power transfer coil of the present invention is designed using the aforementioned integrated isolated DC / DC converter based on a planar wireless power transfer coil, as follows: Figure 1 As shown, it includes planar layers stacked sequentially from bottom to top: 1) Primary-side power module, which includes a primary-side inverter and a primary-side resonant capacitor; 2) The primary side water-cooled plate is connected to the top of the primary side power module on one side and to the ferrite core on the other side, forming the main heat dissipation channel to quickly remove heat from the primary side power devices and the core. 3) Primary magnetic core, used to form a magnetic circuit and provide a magnetic flux channel to improve coupling and power transmission capabilities; 4) Primary side gasket, placed between the primary side magnetic core and the primary side coil, to ensure electrical isolation while establishing a low thermal resistance heat conduction path to dissipate heat from the primary side coil; 5) The primary coil is made of Litz wire wound into a planar helical coil and coupled to the secondary coil to realize wireless power transmission; 6) The H-type solid insulation structure is set between the primary coil and the secondary coil as the main insulation isolation layer. The H-type geometry limits the electrical clearance and creepage distance at critical edges, weakens the field strength at the tip and the weak path along the surface, thereby improving the withstand voltage and insulation reliability and suppressing the development of partial discharge. 7) The secondary coil is located above the H-shaped solid insulation layer and is magnetically coupled with the primary coil to complete isolated power transmission; 8) Secondary side gasket, placed between the secondary side coil and the secondary side magnetic core, is used for secondary side electrical isolation and heat conduction; 9) Secondary magnetic core, used to form a magnetic circuit and provide a magnetic flux channel to improve coupling and power transmission capabilities; 10) Secondary side water-cooled plate, which is integrally connected or fastened to the secondary side power module, is used to remove heat from the secondary side power devices and secondary side coils, forming the main heat dissipation channel on the secondary side and providing structural support. 11) Secondary power module.

[0037] The overall structure is planar, with the magnetic core physically separated, eliminating weak paths of coil-core surface discharge, which is conducive to integrated heat dissipation. The entire structure provides a low thermal resistance heat dissipation channel in the vertical channel.

[0038] The primary coil lead is connected in series with a primary resonant capacitor and then to the primary inverter circuit. The secondary coil lead is connected in series with a secondary resonant capacitor and then to the secondary rectifier. Litz wire is used for both the primary and secondary coils. The spacing between the primary and secondary coils is determined based on the insulation voltage and partial discharge constraints.

[0039] The advantages of the isolated DC / DC integrated method based on planar wireless power transfer coil of the present invention are as follows: With the physical separation of the primary and secondary magnetic cores as the core, and the introduction of solid main insulation technology between the primary and secondary sides as a controllable electrical isolation medium, the weak path of surface discharge of the coil-core of the closed magnetic circuit transformer is eliminated from the structure, which significantly improves the withstand voltage level and long-term insulation reliability. The design incorporates a planar layered structure, insulating thermal pads, and primary and secondary water-cooled plates to create a low thermal resistance heat dissipation channel, achieving efficient heat dissipation and temperature rise control for power devices, coils, and magnetic cores. The planar wireless power transfer coil-power module integrated design balances power density, insulation capability and efficiency, and solves the problems of insulation breakdown and partial discharge that easily occur in SST isolation transformers under medium voltage power frequency and high dv / dt superimposed stress, while traditional thickened insulation / spacing / potting sacrifice window utilization, coupling and thermal management and increase costs.

[0040] A simulation model was built to further verify the correctness of the integrated isolated DC / DC converter based on a planar wireless power transfer coil. The isolated DC / DC topology is CLLC, and the system operating frequency is the resonant frequency. The voltage and current waveforms of its resonant network are shown below. Figure 7 As shown in the figure, the converter can achieve soft switching. When the load experiences a step change, its output voltage remains relatively stable, as shown in the figure. Figure 8 As shown in the figure, CLLC has good constant voltage characteristics.

[0041] Finally, it should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0042] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0043] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Isolated DC / DC integrated method based on planar wireless power transfer coil, characterized in that, The steps are as follows: S1. It adopts a magnetic core-separated planar spiral coil structure, including a primary side coil and a secondary side coil, and a magnetic core is set on the back of the coil, with a spacer between the magnetic core and the coil. S2, the secondary coil, and the primary coil are respectively embedded in the upper and lower layers of the H-type solid insulation structure; S3. Water-cooled plates are installed on the back of the magnetic core. Secondary power modules and primary power modules are installed on the back of the upper and lower water-cooled plates, respectively. S4. Configure the parameters of the isolated DC / DC topology.

2. The planar wireless power transfer coil based isolated DC / DC integrated method of claim 1, wherein, The primary power module includes a primary inverter and a primary resonant capacitor, and the secondary power module includes a secondary resonant capacitor and a secondary rectifier. The lead wire of the primary coil is connected in series with the primary resonant capacitor and then connected to the primary inverter circuit. The lead wire of the secondary coil is connected in series with the secondary resonant capacitor and then connected to the secondary rectifier.

3. The planar wireless power transfer coil-based isolated DC / DC integrated method of claim 1, wherein, Both the primary and secondary coils are planar helical coils wound with Litz wire, and wireless power transmission is achieved through magnetic coupling.

4. The planar wireless power transfer coil-based isolated DC / DC integrated integration method according to claim 1, characterized in that, The H-type solid insulation structure serves as the main insulation between the primary and secondary coils, and its geometric shape limits the electrical clearance and creepage distance to suppress partial discharge.

5. The planar wireless power transfer coil-based isolated DC / DC integrated integration method according to claim 1, characterized in that, The gasket is located between the magnetic core and the side coil, and has both electrical isolation and low thermal resistance heat conduction functions.

6. The planar wireless power transfer coil-based isolated DC / DC integrated integration method according to claim 1, characterized in that, The gaps between the primary coil, the secondary coil, and the H-type insulation structure are encapsulated with epoxy resin to improve the overall insulation and mechanical strength.

7. The method for integrated isolated DC / DC converters based on planar wireless power transfer coils according to claim 1, characterized in that, The water-cooled plate is bonded to the power module and magnetic core to form a vertical heat dissipation path.

8. The planar wireless power transfer coil-based isolated DC / DC integrated integration method according to claim 1, characterized in that, The isolated DC / DC topology uses CLLC, LLC resonant or non-resonant converters.

9. The method for integrated isolated DC / DC converters based on planar wireless power transfer coils according to claim 8, characterized in that, The resonant capacitor parameters of the CLLC topology are set according to the matching of the corresponding leakage inductance and resonant angular frequency.

10. Isolated DC / DC converter based on planar wireless energy transfer coil, characterized by: It is designed using the isolated DC / DC integrated method based on planar wireless power transfer coil as described in any one of claims 1-9.

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