Three-phase LLC topological system supporting three independent input ports

Abstract

The invention relates to the technical field of power electronics, in particular to a three-phase LLC topological system supporting three independent input ports, which comprises an input module, a transformer module and a resonant cavity module which are connected in sequence, and is characterized in that the input module comprises three independent input ports which are used for supporting the input of unbalanced voltage; the transformer module comprises a magnetic integrated three-phase resonant transformer, and the magnetic integrated three-phase resonant transformer adopts a magnetic core structure and is used for providing uniformly distributed magnetic flux; and the resonant cavity module comprises a three-phase staggered LLC resonant cavity and is used for realizing efficient transmission of electric energy and balanced distribution of power. The problems of multi-input voltage imbalance, magnetic loss and power distribution can be solved, and system efficiency, power density and stability are improved.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and particularly to a three-phase LLC topology system supporting three independent input ports. Background Art

[0002] With the rapid development of industries such as electric vehicles, data centers, and other high-efficiency power conversion requirements, traditional power conversion topologies are gradually difficult to meet the requirements of modern applications in terms of efficiency, power density, and volume. In the field of electric vehicles, on-board chargers (OBCs) are key power conversion modules, and their core requirements are high efficiency, high power density, and the flexibility to adapt to various grid inputs. Conventional OBCs generally adopt a two-stage structure, including a front-stage power factor correction (PFC) circuit and a rear-stage LLC resonant converter. Among them, although the traditional single-phase LLC topology is simple in design, it faces problems such as insufficient efficiency, large output ripple, and limited power density in high-power output scenarios. To overcome these limitations, multi-phase interleaved topologies have gradually become a research hotspot. Through the interleaved operation mode, multi-phase topologies can effectively reduce current ripple, reduce the volume of filter capacitors, and improve overall efficiency. However, there are still technical bottlenecks in these topologies in practical applications.

[0003] Multi-phase interleaved LLC topologies face the following key difficulties in applications: First, traditional topologies are difficult to tolerate the imbalance of multi-input voltages. In practical scenarios, due to reasons such as grid fluctuations and uneven load distribution, the voltages of multiple inputs may have a small range of imbalance, which will significantly affect the stability and efficiency of the system, and may even cause additional current losses and component overheating. Second, the loss and heat dissipation problems of magnetic components have always been the core challenges in high-frequency and high-power density applications. Traditional magnetic core structures are difficult to meet the requirements of both low loss and efficient heat dissipation at the same time. Especially under high-frequency operating conditions, the optimization of core loss and winding loss becomes one of the design difficulties. Finally, the power distribution and current sharing problem is a key problem in multi-port systems. To achieve load balancing between multiple inputs, the system needs to design precise power regulation and distribution mechanisms to reduce current fluctuations and efficiency losses caused by imbalance.

[0004] Regarding the above problems, current research and practice have shown that by introducing magnetic integration technology and optimized topology design, the system performance can be effectively improved. Magnetic integration technology integrates the resonant inductor and transformer into a single magnetic core, which can not only significantly reduce the volume of magnetic components, but also optimize the magnetic flux distribution, reduce losses, and increase the power density. In addition, the three-phase LLC topology design that supports multiple independent input ports, combined with the self-equalizing current mechanism, can tolerate small imbalances in the input voltage and achieve efficient power regulation and distribution in the system. This design scheme can improve the overall performance of the power converter while meeting the requirements of efficient energy transfer, high power density, and stability. Therefore, the present invention provides a three-phase LLC topology system that supports three independent input ports. Summary of the Invention

[0005] The object of the present invention is to provide a three-phase LLC topology system that supports three independent input ports, solve the problems of multi-input voltage imbalance, magnetic loss, and power distribution, and improve the system efficiency, power density, and stability.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A three-phase LLC topology system that supports three independent input ports, comprising: an input module, a transformer module, and a resonant cavity module connected in sequence, wherein the input module includes three independent input ports for supporting unbalanced input voltages; the transformer module includes a magnetically integrated three-phase resonant transformer, and the magnetically integrated three-phase resonant transformer adopts a magnetic core structure for providing a uniformly distributed magnetic flux; the resonant cavity module includes a three-phase interleaved LLC resonant cavity for achieving efficient power transmission and balanced power distribution.

[0008] Optionally, the three independent input ports are respectively connected to a front-end AC-DC module, and the front-end AC-DC module is used to make the power distribution of each port consistent by controlling the input power, reducing the influence of unbalanced input voltages.

[0009] Optionally, the integrated three-phase resonant transformer includes a three-phase resonant inductor and a transformer, and the three-phase resonant inductor and the transformer adopt a magnetic core structure with an equilateral triangle layout, and an air gap is provided on the magnetic core column of the magnetic core structure.

[0010] Optionally, by adjusting the size of the air gap, the resonant inductor value is controlled to meet different load conditions, and the relationship between the size of the air gap and the required exciting inductance is:

[0011]

[0012] wherein, L m is the required exciting inductance, l gδ is the air gap size, N is the number of turns of the winding, μ0 is the permeability of free space, and A g is the cross-sectional area of the air gap on the magnetic core column of the corresponding phase.

[0013] Optionally, the magnetic core column is cylindrical, and the relationship between the distance and size between the magnetic core columns of adjacent phases is:

[0014]

[0015] where d is the distance between the magnetic core columns of adjacent phases, r is the radius of the magnetic core column, I rms and J are the effective value of the current flowing through the winding and the current density respectively, n is the number of parallel layers of the winding, h is the thickness of the winding, and e2 is the margin.

[0016] Optionally, the integrated three-phase resonant transformer adopts a distributed winding structure, and each phase winding supports PCB winding, Litz wire winding, and copper foil winding forms.

[0017] Optionally, the distributed winding structure includes any one of a staggered structure, a sandwich structure, and a stacked structure.

[0018] Optionally, the main side of the three-phase interleaved LLC resonant cavity adopts a Y-type connection, and the secondary side adopts an independent DC bus structure. Among them, the Y-type connection enables soft-switching operation for each phase branch by optimizing the parameters of the resonant inductor and resonant capacitor; the independent DC bus structure supports maintaining a varying voltage difference between the buses.

[0019] Optionally, the three-phase LLC topology system adjusts its operating state through a dynamic control algorithm, and the dynamic control algorithm is used to regulate the power of three independent input ports to achieve load balancing and the switching between single-phase mode and three-phase mode.

[0020] The beneficial effects of the present invention are:

[0021] The present invention supports small - range voltage unbalanced operation of three independent input ports, reduces the impact of unbalance on system performance through a self - current - sharing mechanism, and improves the stability and efficiency of the system. It adopts a magnetically integrated three - phase resonant transformer, integrating the three - phase resonant inductor and the transformer in a single magnetic core, and achieving uniform magnetic flux distribution through an equilateral - triangle magnetic - core layout, reducing magnetic loss and winding loss. The main side of the three - phase interleaved LLC resonant cavity of the present invention uses a Y - type connection, and the secondary side is designed as an independent DC - bus structure, effectively avoiding an additional current path on the resonant capacitor, and optimizing the system efficiency through soft - switching operation. It adopts a distributed - winding design, supporting PCB windings, Litz - wire windings, or copper - foil windings, further reducing current ripple, and combining a dynamic control algorithm to optimize resonant parameters and input - power distribution, improving the conversion efficiency and reliability of the system. In summary, the LLC topology with three independent input ports of the present invention is an LLC topology that can tolerate input - voltage unbalance, efficiently distribute power, and improve system performance, meeting the requirements of modern high - power - density power - conversion applications. Brief Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 Schematic structural diagram of a three - phase LLC topology system supporting three independent input ports according to an embodiment of the present invention;

[0024] Figure 2 Schematic diagram of the equilateral - triangle magnetic - core layout of the transformer according to an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the Y - type connection on the main side and the independent DC - bus on the secondary side of the three - phase interleaved LLC resonant cavity according to an embodiment of the present invention;

[0026] Figure 4 Flowchart of the dynamic control algorithm according to an embodiment of the present invention;

[0027] Figure 5 Schematic diagram of the simulation results according to an embodiment of the present invention. Detailed Embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0030] This embodiment provides a three-phase LLC topology system supporting three independent input ports, as Figures 1 - 3 shown, including: an input module, a transformer module, and a resonant cavity module connected in sequence, wherein the input module includes three independent input ports for supporting unbalanced input voltages; the transformer module includes a magnetically integrated three-phase resonant transformer, and the magnetically integrated three-phase resonant transformer adopts a magnetic core structure for providing uniformly distributed magnetic flux; the resonant cavity module includes a three-phase interleaved LLC resonant cavity for realizing efficient power transmission and balanced power distribution.

[0031] Specifically, this embodiment supports the operation of small-range voltage imbalance of three independent input ports, reduces the impact of imbalance on system performance through the self-equalizing current mechanism, and improves the stability and efficiency of the system; adopts a magnetically integrated three-phase resonant transformer, integrates the three-phase resonant inductance and the transformer in a single magnetic core, and realizes uniform magnetic flux distribution through an equilateral triangle magnetic core layout, reducing magnetic loss and winding loss; the main side of the three-phase interleaved LLC resonant cavity in this embodiment adopts a Y-type connection, and the secondary side is designed as an independent DC bus structure, effectively avoiding additional current paths on the resonant capacitors, and optimizing the system efficiency through soft-switching operation; adopts a distributed winding design, supports PCB windings, Litz wire windings or copper foil winding forms, further reduces current ripple, and combines a dynamic control algorithm to optimize the resonant parameters and input power distribution, improving the conversion efficiency and reliability of the system. In summary, the LLC topology with three independent input ports in this embodiment is an LLC topology that can tolerate input voltage imbalance, efficiently distribute power, and improve system performance, and can meet the requirements of modern high-power density power conversion applications.

[0032] Furthermore, the three independent input ports are respectively connected to a front-stage AC-DC module, and the front-stage AC-DC module is used to make the power distribution of each port consistent by controlling the input power, reducing the impact brought by unbalanced input voltages.

[0033] Specifically, in this embodiment, the three independent input ports are respectively connected to the front-stage AC-DC module, which supports a small range of input voltage imbalance, and controls the input power through the front-stage AC-DC module to make the power distribution of each port consistent, thereby achieving load balance and effectively reducing the current loss caused by input asymmetry.

[0034] Furthermore, the integrated three-phase resonant transformer includes a three-phase resonant inductor and a transformer. The three-phase resonant inductor and the transformer adopt a magnetic core structure with an equilateral triangle layout, and air gaps are provided on the magnetic core columns of the magnetic core structure.

[0035] Among them, the resonant inductor value is controlled by adjusting the size of the air gap to meet different load conditions. The relationship between the size of the air gap and the required exciting inductance is:

[0036]

[0037] Wherein, L m is the required exciting inductance, l g is the size of the air gap, N is the number of winding turns, μ0 is the magnetic permeability of vacuum, and A g is the cross-sectional area of the air gap on the magnetic core column of the corresponding phase.

[0038] Among them, the magnetic core columns are cylindrical, and the relationship between the distance and size between the magnetic core columns of adjacent two phases is:

[0039]

[0040] Wherein, d is the distance between the magnetic core columns of adjacent two phases, r is the radius of the magnetic core column, I rms and J are respectively the effective value of the current flowing through the winding and the current density, n is the number of parallel layers of the winding, h is the thickness of the winding, and e2 is the margin.

[0041] Furthermore, the integrated three-phase resonant transformer adopts a distributed winding structure, and each phase winding supports PCB winding, Litz wire winding, and copper foil winding forms. The distributed winding structure includes any one of a staggered structure, a sandwich structure, and a stacked structure.

[0042] Specifically, in this embodiment, the magnetically integrated three-phase resonant transformer adopts an equilateral triangle magnetic core layout. As Figure 2 shown, the three-phase resonant inductor and the transformer are integrated in a single magnetic core structure, optimizing the magnetic flux distribution and significantly reducing the magnetic loss and winding loss. Air gaps are provided on each magnetic core column, and the air gaps are located in the middle or at one end of the magnetic core column. By adjusting the size of the air gap, the resonant inductor value can be precisely controlled to meet different load conditions. The size of the air gap and the required exciting inductance satisfy the following relationship:

[0043]

[0044] where N is the number of turns of the winding, μ0 is the permeability of free space, and A g is the cross-sectional area of the air gap on the magnetic core column of the corresponding phase.

[0045] The magnetic core column is cylindrical, and the distance and size between adjacent magnetic core columns of two phases satisfy the following relationship:

[0046]

[0047] where I rms and J are the effective value of the current flowing through the winding and the current density respectively, n is the number of parallel layers of the winding, h is the thickness of the winding, and e2 is the margin.

[0048] Specifically, the windings of the magnetically integrated three-phase resonant transformer include at least two groups of coils, which form the primary winding and the secondary winding of the transformer respectively, and are wound on the corresponding magnetic core columns. Preferably, the windings are in the form of PCB windings, Litz wire windings or copper foil windings to reduce current ripple and improve system efficiency. The structures of the primary winding and the secondary winding can be selected as interleaved structure, sandwich structure or laminated structure to optimize the magnetic circuit distribution and reduce leakage inductance.

[0049] Furthermore, the main side of the three-phase interleaved LLC resonant cavity adopts a Y-type connection, and the secondary side adopts an independent DC bus structure. Among them, the Y-type connection enables soft-switching operation for each phase branch by optimizing the parameters of the resonant inductor and the resonant capacitor; the independent DC bus structure supports maintaining a varying voltage difference between the buses.

[0050] Specifically, as Figure 3 shown, the main sides A, B, and C of the three-phase interleaved LLC resonant cavity adopt a Y-type connection, and the secondary sides a, b, and c are an independent DC bus structure. By optimizing the parameters of the resonant inductor Lr and the resonant capacitor Cr, soft-switching operation is achieved for each phase branch, thereby significantly reducing switching losses and improving system efficiency. The independent DC bus structure on the secondary side effectively avoids an additional current path on the resonant capacitor and further improves energy efficiency through a stable voltage difference.

[0051] Furthermore, the three-phase LLC topology adjusts its operating state through a dynamic control algorithm. As Figure 4 shown, power regulation is performed on three independent input ports to achieve load balancing and switching between multiple modes (single-phase mode and three-phase mode).

[0052] Specifically, a three-phase LLC topology system supporting three independent input ports proposed in this embodiment is realized through the following steps:

[0053] Step 1: Determine the system parameters. Determine the system operating range, including an input voltage of 90 - 265V, an output voltage of 450 - 900V, and a target power density of 60W / in3 Select a suitable switching frequency and choose an efficient magnetic core material according to the frequency.

[0054] Step 2: Design the magnetically integrated three-phase resonant transformer. Calculate the required exciting inductance and air gap size, design the magnetic core column size and winding turns according to the magnetic core material and working magnetic density, and ensure that the equilateral triangle magnetic core layout realizes uniform magnetic flux distribution.

[0055] Step 3: Design the three-phase interleaved LLC resonant cavity. Determine the topology of the main side Y-connection and the secondary side independent DC bus, optimize the matching values of the resonant inductance and resonant capacitance, and enable soft-switching operation for each phase branch.

[0056] Step 4: Implement the control algorithm. Develop a dynamic control algorithm to adjust the operating state of the three-phase LLC topology, as Figure 4 shown, perform power regulation on the three input ports to ensure load balance and support multi-mode switching (single-phase mode and three-phase mode) to meet the requirements of different application scenarios.

[0057] Conditions for mode switching:

[0058] (1) When the following conditions are met, the system switches to the single-phase mode:

[0059] 1) Under light load conditions, the control algorithm determines that the current load is light through current sharing regulation, and only one module needs to operate to meet the output requirements. At this time, the system selects one module as the main module, and the remaining modules enter the slave module or monitoring state to reduce power consumption and improve light load efficiency.

[0060] 2) In the case of partial module failures, if some modules fail to successfully participate in the competition or detect abnormalities (such as input port disconnection), the system will switch to the single-phase mode to ensure that the system can continue to operate.

[0061] (2) When the following conditions are met, the system switches to the three-phase mode:

[0062] 1) Under heavy load conditions, the control algorithm determines that the load is heavy. To meet the output power requirements, all three input ports need to operate simultaneously. The system will allocate three modules as the main modules to jointly bear the load and ensure balanced power distribution.

[0063] 2) When it is necessary to reduce the current ripple, in scenarios with high requirements for output ripple (such as high-precision power supply), the three-phase interleaved operation mode can effectively reduce the current ripple, thereby improving the output quality.

[0064] As Figure 5As shown, the simulation and experimental results indicate that the topological structure of this embodiment still has good stability under the condition of unbalanced input voltage, and can significantly reduce magnetic loss and switching loss, improving the overall efficiency and power density. Compared with the traditional topology, this embodiment provides a more efficient and reliable solution.

[0065] The embodiments described above are only descriptions of the preferred modes of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A three-phase LLC topology system supporting three independent input ports, characterized in that: include: An input module, a transformer module and a resonant cavity module are connected in sequence, wherein the input module includes three independent input ports, and the three independent input ports are used to support input unbalanced voltage; the transformer module includes a magnetically integrated three-phase resonant transformer, and the magnetically integrated three-phase resonant transformer adopts a magnetic core structure to provide uniformly distributed magnetic flux; the resonant cavity module includes a three-phase staggered LLC resonant cavity to achieve efficient transmission of electric energy and balanced power distribution.

2. The three-phase LLC topology system supporting three independent input ports according to claim 1, characterized in that: The three independent input ports are respectively connected to the front-stage AC-DC modules, and the front-stage AC-DC modules are used to control the input power to make the power distribution of each port consistent, thereby reducing the impact of the unbalanced input voltage.

3. The three-phase LLC topology system supporting three independent input ports according to claim 1, characterized in that: The integrated three-phase resonant transformer comprises a three-phase resonant inductor and a transformer. The three-phase resonant inductor and the transformer adopt a magnetic core structure with an equilateral triangle layout. An air gap is arranged on the magnetic core column of the magnetic core structure.

4. The three-phase LLC topology system supporting three independent input ports according to claim 3, characterized in that: The resonant inductance value is controlled by adjusting the size of the air gap to meet different load conditions. The relationship between the size of the air gap and the required excitation inductance is: Among them, L m is the required excitation inductance, l g is the air gap size, N is the number of winding turns, μ0 is the vacuum permeability, A g is the cross-sectional area of ​​the air gap on the magnetic core column of the phase.

5. The three-phase LLC topology system supporting three independent input ports according to claim 3, characterized in that: The magnetic core column is cylindrical, and the relationship between the distance and size between the magnetic core columns of two adjacent phases is: Where, d is the distance between the two adjacent phases of the magnetic core column, r is the radius of the magnetic core column, I rms , J are the effective value and current density of the current flowing through the winding respectively, n is the number of parallel winding layers, h is the winding thickness, and e2 is the margin.

6. The three-phase LLC topology system supporting three independent input ports according to claim 1, characterized in that: The integrated three-phase resonant transformer adopts a distributed winding structure, and each phase winding supports PCB winding, Litz wire winding, and copper foil winding forms.

7. The three-phase LLC topology system supporting three independent input ports according to claim 6, characterized in that: The distributed winding structure includes any one of a staggered structure, a sandwich structure, and a laminated structure.

8. The three-phase LLC topology system supporting three independent input ports according to claim 1, characterized in that: The three-phase staggered LLC resonant cavity adopts a Y-type connection on the primary side and an independent DC bus structure on the secondary side, wherein the Y-type connection optimizes the parameters of the resonant inductor and the resonant capacitor to achieve soft switching operation for each phase branch; the independent DC bus structure supports maintaining a changing voltage difference between the buses.

9. The three-phase LLC topology system supporting three independent input ports according to any one of claims 1 to 8, characterized in that: The three-phase LLC topology system adjusts the operating state through a dynamic control algorithm, and the dynamic control algorithm is used to adjust the power of three independent input ports to achieve load balancing and switching between single-phase mode and three-phase mode.

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