Multifunction integrated transformer, vehicle power supply system and power conversion method

Abstract

The application relates to the technical field of power electronic conversion, in particular to a multifunctional integrated transformer applied to a new energy automobile, a vehicle-mounted power supply system and a power conversion method. An integrated transformer comprises a magnetic core assembly, a primary winding assembly and a secondary winding assembly, the primary winding assembly and the secondary winding assembly are electromagnetically coupled and are integrated in the magnetic core assembly; the primary winding assembly comprises at least two primary winding units which are electrically connected in series; the secondary winding assembly comprises a first secondary winding unit for outputting a first voltage and a second secondary winding unit for outputting a second voltage; wherein the transformer is configured to provide resonant inductance by using leakage inductance of the primary winding assembly, and the magnetic flux directions of the at least two primary winding units generated in the common magnetic path part of the magnetic core assembly are opposite to form magnetic flux cancellation. Through deep integration of circuit topology and magnetic path function, the application realizes deep fusion and miniaturization of OBC and DCDC.

Description

Technical Field

[0001] This application relates to the field of power electronic conversion technology, and in particular to a multifunctional integrated transformer, on-board power supply system and power conversion method for use in new energy vehicles. Background Technology

[0002] With the increasing severity of the global energy crisis and environmental pollution, the new energy vehicle (NEV) industry has experienced rapid development. In the power system of NEVs, the on-board charger (OBC) and the DC-DC converter are two crucial core components. The OBC converts AC power from the grid into high-voltage DC power to charge the battery, while the DC-DC converter converts the high-voltage DC power from the battery into low-voltage DC power (such as 12V or 24V) to power low-voltage electronic devices such as lights, instruments, and entertainment systems within the vehicle.

[0003] Currently, in traditional new energy vehicle power architectures, the OBC and DC-DC converters typically exist as two independent units, or even if they are simply assembled in terms of physical structure, their internal circuit topologies remain fragmented. Specifically, the OBC module has its own independent main transformer and resonant inductor, and the DC-DC module also has its own independent main transformer. This "separate entities" technical architecture has several fundamental drawbacks: First, the transformer (and inductor) is the largest, heaviest, and most expensive component in the power system. Multiple independent transformers directly lead to low power density and large size of the entire power system, which is detrimental to lightweight vehicle design. Second, in high-voltage applications (such as 800V platforms), traditional single transformers bear extremely high voltage stress, resulting in a sharp increase in core losses (iron losses) and difficulty in heat dissipation. Third, in high-current charging modes, traditional wire-wound transformers suffer from severe copper losses due to proximity and skin effects, and the poor consistency of parasitic parameters in hand-wound transformers easily leads to electromagnetic interference (EMC) problems.

[0004] In response to the technical problems of the aforementioned technologies, such as the large number and size of transformers, low system integration, and high losses under high voltage and high frequency, the industry urgently needs an innovative technical solution that can achieve deep integration and magnetic integration. Summary of the Invention

[0005] The purpose of this application is to provide a multifunctional integrated transformer, vehicle power system and power conversion method, which aims to solve the problems of large size, high cost and high loss of transformers in existing vehicle power systems, and realize the deep integration and miniaturization of OBC and DCDC.

[0006] Firstly, the integrated transformer provided in this application adopts the following technical solution: An integrated transformer includes a magnetic core assembly, a primary winding assembly, and a secondary winding assembly, wherein the primary winding assembly and the secondary winding assembly are electromagnetically coupled and integrated into the magnetic core assembly. The primary winding assembly includes at least two primary winding units electrically connected in series; the secondary winding assembly includes a first primary winding unit for outputting a first voltage and a second secondary winding unit for outputting a second voltage. The transformer is configured to provide resonant inductance using the leakage inductance of the primary winding assembly, and the magnetic flux generated by the at least two primary winding units in the common magnetic circuit portion of the core assembly is in opposite directions to form magnetic flux cancellation.

[0007] Furthermore, both the first-stage winding unit and the second-stage winding unit include multiple sub-windings. The multiple sub-windings in the first-stage winding unit are connected in parallel to share the load current of the first voltage; the multiple sub-windings in the second-stage winding unit are connected in parallel to share the load current of the second voltage.

[0008] Furthermore, the second-stage winding unit is coupled to the primary winding assembly and configured to independently output the second voltage by sensing the magnetic flux in the core assembly.

[0009] Furthermore, the primary winding unit is configured to connect to a high-voltage DC load, and the secondary winding unit is configured to connect to a low-voltage DC load; the series connection node of the primary winding assembly is configured to connect to a voltage divider circuit to balance the voltage.

[0010] Furthermore, the magnetic core assembly is a closed magnetic circuit structure, and the at least two primary winding units are disposed at different magnetic post positions of the magnetic core assembly and configured to generate magnetic flux paths that superimpose or cancel each other within the magnetic core assembly.

[0011] Secondly, the power supply system integrating on-board charging and DC-DC conversion provided in this application adopts the following technical solution: A power system integrating on-board charging and DC-DC conversion, comprising: The primary-side switching circuit is used to convert input electrical energy into alternating current; As described above, the primary winding assembly of the integrated transformer is connected to the output terminal of the primary-side switching circuit. The first output circuit is connected to the primary winding unit of the integrated transformer and is used to connect to the first load. The second output circuit is connected to the second winding unit of the integrated transformer and is used to connect to the second load. The primary-side switching circuit and the leakage inductance of the integrated transformer together constitute a resonant converter circuit.

[0012] Furthermore, the primary-side switching circuit includes a full-bridge switching network; a voltage-dividing capacitor bank is connected between the series midpoint of the primary winding assembly and the midpoint of the bridge arm of the full-bridge switching network, the voltage-dividing capacitor bank being configured to balance the voltage on the at least two primary winding units (21, 22).

[0013] Furthermore, the second output circuit includes a controllable switching device configured to adjust the output voltage and / or current of the second load terminal by adjusting the conduction state of the controllable switching device when the primary-side switching circuit is operating.

[0014] Thirdly, this application provides a power conversion method comprising the following steps: The primary-side switching circuit is controlled to operate, driving current to flow through the primary winding assembly connected in series. Soft switching is achieved by utilizing the resonance between the leakage inductance of the integrated transformer and the capacitance parameters in the circuit. Energy is coupled through the magnetic core assembly, and a first voltage is induced and output using the first-stage winding unit, and a second voltage is induced and output using the second-stage winding unit.

[0015] In summary, this application includes at least one of the following beneficial technical effects: 1. By using leakage inductance to replace independent resonant inductors and integrating the OBC transformer and DC-DC transformer into the same core assembly, the number of transformers and the overall volume are significantly reduced.

[0016] 2. The primary series structure is adopted to share the high voltage input, which reduces the voltage stress and core loss of a single winding unit; the secondary parallel structure is adopted to share the large current output, which effectively reduces the copper loss of the winding and improves the system efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall circuit topology of the transformer; Figure 2 This is a schematic diagram of the overall circuit topology after the transformer is integrated into the power supply system; Figure 3 This is a 3D schematic diagram of a transformer.

[0019] In the diagram: 10, magnetic core assembly; 20, primary winding assembly; 21, first primary winding unit; 22, second primary winding unit; 30, secondary winding assembly; 31, first primary winding unit; 32, second secondary winding unit; 100, primary side switching circuit; 200, integrated transformer; 300, first output circuit; 400, second output circuit. Detailed Implementation

[0020] The technical solution of this application will now be clearly and completely described with reference to the accompanying drawings. The following embodiments are exemplary and are only used to explain this application, and should not be construed as limiting this application. In the following description, the same reference numerals are used to denote the same or equivalent elements, and repeated descriptions are omitted.

[0021] In the description of this application, it should be understood that the terms "upper", "lower", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this application and to simplify the description, and are not intended to indicate or imply that the equipment or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] Furthermore, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] It should also be further understood that the term “and / or” as used in this application refers to any combination of one or more of the listed items, and all possible combinations thereof.

[0024] Example 1: A multifunctional integrated transformer is proposed to address the problems of large size and low integration of magnetic components in vehicle power systems. (Refer to...) Figure 1 and Figure 2 The transformer 200 includes a magnetic core assembly 10, a primary winding assembly 20, and a secondary winding assembly 30.

[0025] In this embodiment, refer to Figure 3 Both the primary winding assembly 20 and the secondary winding assembly 30 are printed windings, which are located within a printed circuit board (PCB).

[0026] For example, the printed circuit board can be a multilayer board structure, with the windings formed by flat spiral traces etched onto the circuit layers. Compared to traditional enameled wire windings, printed windings reduce parasitic parameters to improve EMC performance and occupy less space, making them suitable for high power density applications.

[0027] In one specific embodiment, the substrate of the printed circuit board can be selected from materials with good insulation and thermal conductivity, such as FR-4 high TG board, ceramic substrate, or metal-based copper-clad laminate. Based on this, in another specific embodiment, the winding coil is formed into a flat helical trajectory on a thick copper foil through an etching process.

[0028] Reference Figure 1 The primary winding assembly 20 includes at least two primary winding units. In one specific embodiment, the primary winding assembly 20 includes a first primary winding unit 21 (Np1) and a second primary winding unit 22 (Np2). The two units are electrically connected in series. Through series voltage division, each primary winding unit only needs to withstand a portion of the total voltage. For example, when the total input voltage is 800V, each winding unit only needs to withstand a voltage stress of 400V. This not only reduces the requirements for PCB insulation level but also effectively suppresses core losses under high frequency and high voltage.

[0029] The secondary winding assembly 30 includes a primary winding unit 31 for outputting a first voltage (HVDC) and a secondary winding unit 32 for outputting a second voltage (LVDC). The primary winding unit 31 includes multiple sub-windings (Ns1 and Ns2 combined), which are coupled to corresponding primary winding units (21 and 31 coupled, 22 and 32 coupled) and connected in parallel at the output.

[0030] This parallel structure is mainly designed for high-current applications, such as the high-power charging mode of OBC. Parallel current shunting halves the current flowing through each sub-winding. Assuming a charging current requirement of 100A, through parallel current shunting, each sub-winding only needs to bear 50A, thereby reducing copper losses to one-quarter of the original and greatly solving the heat dissipation problem.

[0031] The second-stage winding unit 32 is consistent with the first-stage winding unit 31 and also includes multiple sub-windings (Ns3 and Ns4 combination). The second-stage winding unit 32 shares the same magnetic circuit of the core assembly 10 with the primary winding assembly 20, thereby using the same transformer body to realize additional voltage conversion functions (such as DC-DC function, to eliminate the need for a DC-DC transformer).

[0032] It should be noted that, Figure 1 It is mainly used to demonstrate the matrix winding connection principle and leakage inductance distribution diagram inside the integrated transformer 200. Although Figure 1 The example illustrates the parallel connection of the output terminals of all secondary windings (Ns1 to Ns4), but in the preferred embodiment of this application applied to an on-board charging and distribution system, the output terminals of the first secondary winding unit 31 and the second secondary winding unit 32 are electrically independent of each other. Specifically, as shown in the example... Figure 2 As shown, the first-stage winding unit 31 independently outputs the first voltage, and the second-stage winding unit 32 independently outputs the second voltage; the two are not directly short-circuited.

[0033] Furthermore, transformer 200 is also configured to utilize the leakage inductance of primary winding assembly 20 to provide resonant inductance. Figure 1 and Figure 2 In the circuit principle, no independent physical inductor is used as the resonant inductor Lr; instead, the leakage inductance of the integrated transformer 200 is directly utilized. Specifically, refer to... Figure 1 Lr1 and Lr2 are the equivalent inductances formed by the leakage flux inherent in the transformer winding structure.

[0034] For example, the leakage inductance can be precisely controlled by adjusting the distance between the primary winding layers (21, 22) and the secondary winding layers (32, 32) in the printed circuit board, or by adjusting the overlap area between the windings. Regarding the core assembly 10, it acts as a closed magnetic circuit structure, carrying the magnetic flux of all the windings. The core assembly 10 includes at least two primary winding units 21, 22, which are disposed on different magnetic pillars of the core assembly 10 to form a predetermined magnetic flux path within the core assembly 10, thereby optimizing the core's volume and losses and achieving magnetic integration.

[0035] Example 2: A power supply system integrating on-board charging and DC-DC conversion, referring to... Figure 2 It includes a primary-side switching circuit 100, an integrated transformer 200, a first output circuit 300, and a second output circuit 400.

[0036] Primary-side switching circuit 100 (corresponding to) Figure 2 The orange area on the left is used to convert direct current into high-frequency alternating current. Exemplarily, the primary-side switching circuit 100 includes a full-bridge switching network 110 composed of switching transistors Q3, Q8, Q2, and Q4. Exemplarily, these switching transistors may be silicon-based IGBTs, SiC MOSFETs, or GaN HEMTs.

[0037] To accommodate the primary series structure of the integrated transformer 200, the primary-side switching circuit 100 also includes a voltage divider capacitor bank (corresponding to...). Figure 2(Cin1 and Cin2 in the diagram). The midpoint of the voltage divider capacitor bank 120 is connected to the series midpoint of the primary winding of the transformer, which plays a role in automatically balancing the voltage and preventing a transformer unit from being subjected to excessive voltage due to inconsistent parameters.

[0038] First output circuit 300 (corresponding to) Figure 2 The blue area on the right is connected to the first winding unit 31 of transformer 200, typically serving as the output stage of the on-board charger (OBC) and connected to the high-voltage power battery. The first output circuit 300 is a full-bridge rectifier circuit (including Q25, Q122, Q26, and Q119), responsible for rectifying the high-frequency AC output from the transformer into DC. After filtering by the filter capacitor Co_HV, it outputs HVDC+ and HVDC-, directly charging the high-voltage power battery of the electric vehicle. This is the OBC function of the system.

[0039] Second output circuit 400 (corresponding to) Figure 2 The green area on the right is connected to the second winding unit 32 of the integrated transformer 200, serving as the output stage of the DC-DC converter and connected to a low-voltage battery. To achieve decoupled control of the OBC and DC-DC functions, the second output circuit 400 includes a controllable rectifier switch network consisting of Q11, Q12, Q13, and Q14.

[0040] Unlike simple diode passive rectification, these switching transistors (MOSFETs) are controllable. While the primary-side switching circuit 100 operates according to the requirements of the OBC, the second output circuit 400 can independently adjust the voltage or current output to the low-voltage side by adjusting the conduction phase or duty cycle of its internal switching transistors, thereby achieving non-interference between the two outputs.

[0041] Example 3: This application also provides a power conversion method, including the following steps: S1: Control the primary-side switching circuit 100 to operate, driving current to flow through the primary winding assembly 20 connected in series.

[0042] The controller drives the full-bridge network of the primary-side switching circuit 100 to generate a high-frequency square wave voltage. This voltage is applied to the primary winding assembly 20. At this time, the current in the circuit flows not only through the magnetizing inductance of the transformer, but also through the leakage inductance Lr integrated inside the transformer 200. The leakage inductance Lr resonates with an external resonant capacitor (Cr or Cp) connected in parallel or series.

[0043] This resonant effect causes the voltage or current to be zero (ZVS / ZCS) at the instant the switching transistor is turned on or off, which greatly reduces switching losses and allows the system to operate at higher frequencies (such as above 300kHz), further reducing the size of passive components.

[0044] S2: Soft switching is achieved by utilizing the leakage inductance of the integrated transformer 200 to resonate with the capacitance parameters in the circuit.

[0045] During energy transfer, current flows through the first primary winding unit 21 and the second primary winding unit 22 connected in series. Due to the preset polarity of the PCB wiring, these two windings generate magnetic flux in their respective magnetic pillars. When these two magnetic circuits converge at a common leg, the controller ensures that the current flowing through the primary windings is in phase, thereby causing the two magnetic fluxes to cancel each other out at the common leg.

[0046] S3: Energy is coupled through the magnetic core assembly 10, and a first voltage is induced and output by the first primary winding unit 31, and a second voltage is induced and output by the second secondary winding unit 32.

[0047] For OBC mode: The controller mainly adjusts the switching frequency (PFM) or phase shift angle of the primary side switching circuit 100 to regulate the total energy transmitted to the first output circuit 300, thereby controlling the charging current or voltage.

[0048] For DC-DC mode: The controller monitors the voltage at the LVDC output. When a voltage fluctuation is detected, the on-time or phase of the synchronous rectifier in the second output circuit 400 is independently adjusted.

[0049] For example, if the OBC requires high power output and the primary side has sufficient energy, and the DC-DC load is relatively light, the low-voltage output circuit 400 will reduce the duty cycle and limit the energy flow by chopping, thereby ensuring that the 12V output is stable at around 14V, without being disturbed by the high-voltage side fluctuations of 800V or 400V.

[0050] The method first controls the primary-side switching circuit 100 to operate, generating a high-frequency current to drive the series-connected primary winding assembly 20. During this process, the leakage inductance of the integrated transformer 200 resonates with the capacitance (e.g., Cp) in the circuit, helping the switching transistor achieve soft switching and reducing switching losses. Energy is coupled to the secondary side through the core assembly 10.

[0051] In the first output circuit 300, the parallel sub-windings in the primary winding unit 31 share the large current, outputting high-voltage electrical energy to charge the power battery. Simultaneously, in the second output circuit 400, the secondary winding unit 32 induces a voltage, which is rectified and regulated by controlling the switching devices in the second output circuit 400 to supply power to low-voltage equipment. The entire process utilizes an integrated transformer to achieve the conversion and transmission of multiple voltage levels.

[0052] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A multifunctional integrated transformer, characterized in that, It includes a magnetic core assembly (10), a primary winding assembly (20) and a secondary winding assembly (30), wherein the primary winding assembly (20) and the secondary winding assembly (30) are electromagnetically coupled and integrated in the magnetic core assembly (10); The primary winding assembly (20) includes at least two primary winding units (21, 22) electrically connected in series; the secondary winding assembly (30) includes a first primary winding unit (31) for outputting a first voltage and a second secondary winding unit (32) for outputting a second voltage. The transformer is configured to provide resonant inductance using the leakage inductance of the primary winding assembly (20), and the magnetic flux generated by the at least two primary winding units (21, 22) in the common magnetic circuit portion of the core assembly (10) is in opposite directions to form magnetic flux cancellation.

2. The multifunctional integrated transformer according to claim 1, characterized in that, Both the first-stage winding unit (31) and the second-stage winding unit (32) include multiple sub-windings. The multiple sub-windings in the first-stage winding unit (31) are connected in parallel to share the load current of the first voltage; the multiple sub-windings in the second-stage winding unit (32) are connected in parallel to share the load current of the second voltage.

3. The multifunctional integrated transformer according to claim 2, characterized in that, The second winding unit (32) is coupled to the primary winding assembly (20) and configured to independently output the second voltage by sensing the magnetic flux in the core assembly (10).

4. The multifunctional integrated transformer according to claim 2 or 3, characterized in that, The primary winding unit (31) is configured to connect to a high-voltage DC load, and the secondary winding unit (32) is configured to connect to a low-voltage DC load; the series nodes of the primary winding assembly (20) are configured to connect to a voltage divider circuit to balance the voltage.

5. The multifunctional integrated transformer according to claim 1, characterized in that, The magnetic core assembly (10) is a closed magnetic circuit structure. The at least two primary winding units (21, 22) are located at different magnetic column positions of the magnetic core assembly (10) and are configured to generate magnetic flux paths that superimpose or cancel each other inside the magnetic core assembly (10).

6. A power supply system integrating on-board charging and DC-DC conversion, characterized in that, include: The primary-side switching circuit (100) is used to convert input electrical energy into alternating current. The transformer (200) according to any one of claims 1 to 5, wherein its primary winding assembly (20) is connected to the output terminal of the primary-side switching circuit (100); The first output circuit (300) is connected to the primary winding unit (31) of the integrated transformer (200) and is used to connect to the first load; The second output circuit (400) is connected to the second winding unit (32) of the integrated transformer (200) for connecting a second load; The primary-side switching circuit (100) and the leakage inductance of the integrated transformer (200) together constitute a resonant converter circuit.

7. The power supply system according to claim 6, characterized in that, The primary-side switching circuit (100) includes a full-bridge switching network; a voltage divider capacitor bank is connected between the series midpoint of the primary winding assembly (20) and the midpoint of the bridge arm of the full-bridge switching network, the voltage divider capacitor bank being configured to balance the voltage on the at least two primary winding units (21, 22).

8. The power supply system according to claim 6, characterized in that, The second output circuit (400) includes a controllable switching device configured to adjust the output voltage and / or current of the second load terminal by adjusting the conduction state of the controllable switching device when the primary-side switching circuit (100) is operating.

9. A power conversion method based on the power supply system of claim 6, characterized in that, Includes the following steps: The primary-side switching circuit (100) is controlled to operate, driving current to flow through the primary winding assembly (20) connected in series. Soft switching is achieved by utilizing the leakage inductance of the integrated transformer (200) and the capacitance parameters in the circuit to resonate. Energy is coupled through the magnetic core assembly (10), and a first voltage is sensed and output by the first primary winding unit (31), and a second voltage is sensed and output by the second secondary winding unit (32).

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