A runway type magnetic core combined with a flat coil three-phase common mode inductor and a preparation device thereof

Abstract

The application discloses a runway type magnetic core combined with a flat coil three-phase common mode inductor and a preparation device thereof. The inductor is combined with an integrated double runway type magnetic core and a structured flat coil, and a temperature and magnetic flux sensing network is integrated in the magnetic core. Meanwhile, a phase balance module with real-time signal processing and dynamic compensation capability and an integrated test interface are provided, so that an intelligent filtering system with state sensing and self-adaptive adjustment capability is formed. The application solves the problem of inconsistent performance of a traditional three-phase common mode inductor caused by manufacturing tolerance, realizes online compensation and optimization of performance drift under complex working conditions, and thus obtains excellent and stable common mode suppression performance in a wide frequency range.

Description

Technical Field

[0001] This invention relates to the field of three-phase common-mode inductor technology, and more particularly to a three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil, and an apparatus for its fabrication. Background Technology

[0002] In three-phase AC or DC converter systems, common-mode inductors are used to suppress high-frequency common-mode interference and improve electromagnetic compatibility (EMC) performance. Most existing three-phase common-mode inductors use traditional toroidal or UI-type magnetic cores with enameled wire coils. In order to improve power density and adapt to high-frequency applications, designs using flat coils to reduce AC resistance and parasitic capacitance, or using magnetic cores of specific shapes to optimize the magnetic circuit layout, have also emerged.

[0003] While pursuing high power density and excellent high-frequency characteristics, existing technologies struggle to fully guarantee and verify the symmetry and consistency of the three-phase windings within the magnetic core during manufacturing. Subtle winding variations, core material inhomogeneities, or assembly tolerances can all lead to deviations in the inductance, DC resistance, or distributed parameters of the three-phase windings. This inherent asymmetry can cause incomplete cancellation of the three-phase magnetic flux during actual operation, reducing common-mode impedance at specific frequency bands and potentially generating additional differential-mode noise, thus affecting the overall filter performance. Furthermore, existing inductors are mostly "passive" components, their performance fixed after manufacturing. Facing complex and variable application conditions (such as switching frequency variations, load fluctuations, and temperature rise effects), the lack of mechanisms for online monitoring and dynamic performance fine-tuning at the system level limits their potential in high-end or adaptive power supply systems.

[0004] Therefore, in response to the problems mentioned above, this invention proposes a three-phase common-mode inductor with a racetrack-shaped magnetic core combined with a flat coil and a fabrication apparatus thereof. Summary of the Invention

[0005] To overcome the shortcomings of existing three-phase common-mode inductors in terms of manufacturing consistency assurance and adaptive control of operating status, this invention proposes an intelligent three-phase common-mode inductor system and its fabrication device that integrates phase balance monitoring and dynamic compensation functions, and combines online testing and feedback correction in the fabrication process.

[0006] The technical solution of this invention is: a three-phase common-mode inductor with a racetrack-shaped magnetic core combined with a flat coil, comprising: The magnetic core unit uses nanocrystalline or ferrite materials with high permeability and low loss. The magnetic core unit contains at least two parallel racetrack-shaped magnetic cores. The racetrack-shaped magnetic cores are integrally formed by connecting bridges to form multiple parallel independent magnetic circuit channels. The cross-section of the racetrack-shaped magnetic core is rectangular or elliptical, and its long side is arranged parallel to the wide side of the flat coil. The surface of the magnetic core is covered with an insulating and thermally conductive coating, and a distributed temperature sensor is embedded in the coating. The coil unit includes three flat Litz wire windings corresponding to the three-phase circuit. Each winding is wound on the magnetic circuit channel at a predetermined interval and angle. The lead-out end of each winding is provided with a high-frequency adaptive terminal interface. The flat Litz wire winding adopts a multi-layer PCB printed coil or flat copper wire vertical winding structure. Polyimide insulation layer is provided between each layer. The winding end is connected to the high-frequency adaptive terminal interface by laser welding. The phase balance module, integrated inside or on the surface of the core unit, includes a distributed capacitor compensation network and a magnetic flux detection coil for real-time monitoring and adjustment of the magnetic flux balance state of the three-phase winding. It also includes a digital signal processor that receives the induced signal from the magnetic flux detection coil and performs real-time phase calibration through an adjustable capacitor array in the capacitor compensation network. An integrated test interface is located in the system shell and communicates with the phase balance module and external test equipment. It is used to collect inductance, leakage inductance, common mode impedance and temperature rise parameters online. It supports multiple communication protocols, including SPI, IIC or CAN bus, and can upload monitoring data to external quality management system or production execution system in real time. The adaptive control unit, based on real-time data from the test interface, dynamically optimizes the common-mode rejection characteristics of the device over a wide frequency range by adjusting the capacitance of the capacitor compensation network or connecting a parallel damping resistor.

[0007] This invention proposes a fabrication apparatus for a three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil, comprising: An automatic feeding and positioning mechanism for magnetic cores is used to transport racetrack-shaped magnetic cores to the assembly station. The coil winding and welding unit, including a multi-axis robotic arm and a vision positioning system, is used to wind flat coils onto a magnetic core and complete terminal welding. The winding head has a tension adaptive control function, which can adjust the winding tension in real time according to the width and thickness of the flat wire. The phase balance module mounting module uses high-precision dispensing and patch technology to integrate the capacitor compensation network and the magnetic flux detection coil into a predetermined position on the magnetic core. The online integrated test station integrates an LCR tester, a network analyzer, and a thermal imager to simultaneously test the electrical and thermal performance of assembled products. It also includes an aging test module that can perform cyclic power-on tests on products in high temperature and high humidity environments and record performance degradation data. The data feedback system records the test data of each product and compares it with the design parameters. It automatically adjusts the winding tension, welding parameters or mounting position to compensate for deviations. It analyzes historical production data through machine learning algorithms, predicts and optimizes process parameters, and achieves adaptive process adjustment. The three-dimensional optical inspection unit is used to perform three-dimensional scanning on the assembled product and compare it with the digital twin model to check whether the structural dimensions and assembly accuracy meet the design requirements.

[0008] The beneficial effects of this invention are: 1. This invention combines an integrated racetrack-shaped magnetic core with a highly regular flat coil to ensure the three-phase symmetry of the magnetic circuit and the electrical circuit. It also utilizes an intelligent manufacturing device that integrates three-dimensional optical detection and data closed-loop feedback to achieve real-time monitoring and adaptive adjustment of key process parameters such as winding, mounting, and welding. This solves the performance dispersion problem caused by manual operation, material fluctuations, and assembly tolerances in traditional manufacturing methods.

[0009] 2. This invention embeds a distributed temperature and flux sensing network inside the magnetic core and integrates a phase balance module with real-time signal processing and decision-making capabilities. This enables the inductor to monitor the balance state and temperature rise of its three-phase flux online and to perform dynamic fine-tuning through a digitally adjustable capacitor compensation network. This effectively compensates for performance drift caused by changes in operating conditions, component aging, or thermal stress, transforming the inductor from a passive component with fixed parameters into an intelligent system that can adaptively maintain the optimal filtering state. Attached Figure Description

[0010] Figure 1 The diagram shown is a schematic representation of the inductor structure of the present invention. Figure 2 The diagram shown is a schematic representation of the preparation apparatus of the present invention. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] Please see Figure 1 This invention provides an embodiment: a three-phase common-mode inductor with a racetrack-shaped magnetic core combined with a flat coil, comprising: The magnetic core unit adopts an integrated dual-racetrack structure. The magnetic core material can be selected according to the application frequency band. For mid-frequency applications with a frequency range of 50kHz-1MHz, manganese-zinc power ferrite with an initial permeability ≥10000 is preferred. It is formed by mold pressing to ensure the dimensional accuracy of the two racetrack-shaped magnetic cores and the intermediate connecting bridge (tolerance controlled within ±0.05mm). For high-frequency applications with a frequency range of 1MHz-30MHz, nanocrystalline ribbon with high saturation magnetic flux density (Bs≥1.2T) and high-frequency low loss characteristics is selected. After winding, heat treatment and epoxy resin vacuum impregnation and curing, it is precision ground to form the required racetrack-shaped cross section.

[0013] Before the thermally conductive insulating coating (such as epoxy resin doped with boron nitride filler) is applied, a miniature PT100 thin-film temperature sensor array is embedded on the long side surface of each racetrack-shaped magnetic core using laser etching or precision printing processes (e.g., one sensor at the center and one at each end of each long side). The connecting bridge area has recesses reserved for mounting miniature Rogowski coils for flux detection. This design transforms the magnetic core not only into a magnetic circuit carrier but also into a distributed physical information (temperature and flux) acquisition substrate. By monitoring the temperature at key points within the core, it can assess the uniformity of temperature rise and hot spots in real time, preventing localized overheating failure. Through the flux detection coils, it can directly measure the instantaneous flux flowing through each independent magnetic circuit, providing the most direct raw data for three-phase balance analysis.

[0014] The coil unit uses flat conductors to achieve low AC resistance and low parasitic capacitance, and includes two main forms: one is using PCB technology, where the three-phase windings are etched in a precision wiring pattern onto 4-6 layers of FR-4 or higher frequency Rogers board, with interlayer series connection via vias, forming a planar winding with extremely regular structure and highly consistent parameters. The PCB coil can be directly mounted on the magnetic core surface and connected to the terminals via high-temperature solder. The other method uses flat copper wire (0.5-1.0mm thick, 2-5mm wide) for vertical winding, using automated winding equipment to control the winding angle and tension, with high-temperature resistant polyimide film tape used for insulation between turns.

[0015] Both PCB coils and flat copper wire coils have their leads connected to a "high-frequency adaptive terminal interface." This interface is a replaceable module integrating a miniature matching network. The module contains a simple π-type or T-type network composed of miniature surface-mount inductors and capacitors to compensate for minor impedance mismatches caused by lead length or external connections, ensuring that high-frequency signals (>10MHz) can enter the inductor body for filtering without loss. The flat conductor of this coil unit significantly reduces skin effect and proximity effect losses at high frequencies.

[0016] The phase balancing module consists of two parts: a hardware compensation network and a digital processing unit. Specifically: The hardware component, the distributed capacitance compensation network, is a multi-channel adjustable RC network fabricated using thick-film hybrid integrated circuit (HIC) or low-temperature co-fired ceramic (LTCC) technology. This network is directly mounted near the magnetic core bridge or on the system PCB substrate, connected to the tap points of the three-phase windings via fine traces. Capacitors in the network can be connected to surface-mount capacitors of different values ​​(such as combinations of 1pF, 10pF, 100pF, and 1nF) via a miniature MOSFET switch array, enabling digital step adjustment of the capacitance. Digital potentiometers can be used for the resistors.

[0017] The digital processing unit (DSP or high-performance MCU) acquires signals from the flux detection coil in real time (converted by a high-precision ADC). It calculates the standard deviation of the effective value of the three-phase flux signal within one power frequency cycle and defines it as the "three-phase flux imbalance". At the same time, it performs FFT analysis on the flux waveform to obtain the amplitude at specific switching frequency harmonics (such as 100kHz, 150kHz).

[0018] The dynamic adjustment mechanism is as follows: During system power-on initialization, the DSP controls the capacitor compensation network to scan in a preset mode, recording the capacitor configuration that minimizes the three-phase flux imbalance and setting it as the initial operating point. During online operation, the DSP continuously monitors the phase flux imbalance and critical harmonic amplitude. If the three-phase flux imbalance exceeds a threshold (e.g., set to 5% of the initial value) due to temperature rise, component aging, or grid disturbances, or if the harmonic amplitude at a specific frequency increases by more than 3dB, the DSP will initiate a fine-tuning algorithm to re-search for the optimal capacitor configuration within a small range near the minimum capacitor configuration, thereby pulling the system back to its optimal balance state. If the adjustment is ineffective, a warning signal is issued through the integrated test interface. This mechanism ensures that the inductor maintains near-factory optimal common-mode rejection performance throughout its entire lifespan.

[0019] The integrated test interface is a standard physical and protocol interface. During manufacturing, it serves as the access point for the production testing system, allowing test stations to read the product serial number with a single click and automatically complete a full set of electrical performance tests. During user application, it can be used as a reserved diagnostic interface, allowing maintenance personnel to use portable devices to read operational status data (such as three-phase imbalance, temperatures at various points, and historical adjustment records). Furthermore, all data generated during manufacturing and operation is uploaded to the cloud platform via this interface or wireless module, forming a digital twin archive of the product. This data is then used to optimize the process parameters of the manufacturing equipment. For example, if the three-phase imbalance value of a batch of products generally drifts after high-temperature aging, data analysis may indicate that the winding tension parameter needs adjustment, and the manufacturing equipment will automatically correct the production parameters of subsequent products accordingly.

[0020] Please see Figure 2The preparation process of the preparation apparatus of the present invention will be described as follows: (1) The coiled magnetic core blanks or sintered magnetic cores are fed into the production line by an automatic feeding mechanism (vibrating plate or robotic arm). First, they pass through a rapid vision inspection unit (which can be classified as part of the automatic magnetic core feeding and positioning mechanism) to perform machine vision screening for appearance defects (cracks, chipped edges) and basic dimensions. Defective products are rejected. Qualified magnetic cores enter a precision coating station, where an insulating and thermally conductive coating is applied to specific areas (racetrack-shaped long side, connecting bridge groove) on the surface of the magnetic core by a program-controlled dispensing machine. At the same time, a high-precision patching robotic arm is used to precisely mount the pre-fabricated miniature temperature sensor film and miniature Rogowski coil onto the pre-set pits or positions of the coating. This process is completed by the subsystem of the phase balance module mounting module, because the sensor is the front-end component for phase balance monitoring. After coating and mounting, the magnetic core enters a low-temperature curing oven for curing. After curing, the servo positioning platform of the automatic magnetic core feeding and positioning mechanism, with mechanical clamps and vision assistance, transfers and fixes the magnetic core to the subsequent coil winding fixture plate with a positioning accuracy of ±0.02mm, in preparation for winding.

[0021] (2) The coil winding and soldering unit begins operation, following the process settings (PCB coil or flat copper wire coil). Specifically: For PCB coils, a multi-axis robotic arm removes the pre-made multi-layer PCB coil from the material box, precisely aligns it with the magnetic core on the tooling plate using a vision positioning system, and then performs hot pressing or welding to firmly bond the back of the coil to the surface of the magnetic core.

[0022] For flat copper wire coils, a dedicated winding head picks up the flat copper wire from the spool and, under program control, winds it vertically on the pre-positioned magnetic core track column with constant tension (maintained by a tension adaptive control system) and precise spacing. During the winding process, the winding angle and number of turns are monitored in real time.

[0023] Once the coil is wound, its ends are guided to a pre-defined terminal area. A high-frequency laser welding head or a precision resistance welding machine, which integrates the coil winding and welding unit, automatically welds the coil leads to the high-frequency adaptive terminal interface. The welding process is monitored by a thermal imager to ensure consistent welding quality and prevent incomplete welds or overheating.

[0024] (3) The semi-finished product carrying the magnetic core and coil is transferred to a dedicated mounting station. The phase balancing module mounting module is started, and its high-precision pick-up head picks up the capacitor compensation network, digital processor and other passive components from the feeder. According to the circuit design, it is mounted on the PCB substrate reserved by the system or directly mounted in the dedicated area near the magnetic core connecting bridge. Fine-pitch wire bonding or selective laser welding technology is used to electrically connect the I / O port of the phase balancing module to the sensor (temperature, magnetic flux detection coil) on the magnetic core and the tap point of the coil.

[0025] (4) Testing is conducted at the online integrated test station. First, the product enters the shielded test chamber, and the test probes automatically connect to the integrated test interface. The LCR tester automatically measures the three-phase inductance, DC resistance, and inter-turn capacitance. The network analyzer scans the common-mode and differential-mode insertion loss curves from 10kHz to 50MHz. The rated DC bias current is applied to test the inductance attenuation characteristics. Then, the product is powered on to activate the phase balance module. The test system sends instructions to the DSP through the interface to drive the capacitor compensation network to scan and simultaneously read the signal of the magnetic flux detection coil. The system automatically optimizes to find the capacitor configuration that minimizes the three-phase magnetic flux imbalance and burns this configuration parameter into the non-volatile memory of the DSP to complete the initial factory calibration of the product. At the same time, the three-phase magnetic flux imbalance value, self-resonant frequency, and key frequency impedance are recorded as factory reference data. Finally, the integrated thermal imager is used to apply a short-time rated current to the product to quickly capture its surface temperature rise distribution and check for abnormal hot spots, indirectly verifying the coil welding and heat dissipation design.

[0026] (5) Products that pass the test enter the 3D optical inspection unit, which uses a structured light or laser scanner to perform a full-range 3D scan of the product, generating high-precision point cloud data. The point cloud data obtained from the scan is automatically compared with the product's CAD digital twin model in a computer. The system analyzes key dimensions, such as coil protrusion height, terminal coplanarity, or module mounting position deviation, to ensure the consistency between the physical product and the design model. Components that exceed the tolerance range will be marked. Products that pass the 3D inspection are picked up by a robotic arm and placed into a protective shell. If potting is required, the product enters a vacuum potting equipment for filling and curing of sealing materials. Finally, a laser marking machine engraves a unique serial number and a QR code for key parameters on the product shell.

[0027] (6) The entire process is connected by a data feedback system. Starting from the initial inspection of the magnetic core, the unique serial number of each product is bound to all its manufacturing data, including raw material batch, winding tension, welding energy, mounting coordinates, all test data (original waveforms and results), 3D scanning deviation diagrams, and calibration parameters. The data feedback system monitors the key process parameters (such as adhesive application amount, winding tension, and welding temperature) and test results of each station in real time. If any parameter exceeds the control limit or the test fails, the system will immediately alarm and suspend the relevant station to prevent batch defects. The test results of the online integrated testing station, especially the data reflecting product consistency (such as the distribution of three-phase magnetic flux imbalance values ​​and the dispersion of insertion loss), are continuously input into the data analysis engine. The data feedback system uses statistical analysis and machine learning algorithms to find hidden correlations between manufacturing process parameters (such as winding speed and mounting pressure) and the performance of the final product. For example, the system may find that the three-phase magnetic flux imbalance value of the product is most concentrated when the winding tension is controlled within a certain range. The system will then automatically send this optimization parameter to the coil winding and welding unit for the production of all subsequent products, thereby achieving adaptive iterative optimization of the manufacturing process and continuously improving the consistency and reliability of the products.

[0028] This invention provides Embodiment 1: This embodiment focuses on 380V / 50Hz input filtering for general industrial frequency converters, targeting a suppression frequency band of 150kHz-30MHz. Its magnetic core unit uses PC95 manganese-zinc ferrite material, with a dual-racetrack structure measuring 45mm on the long axis, 20mm on the short axis, and 15mm in height. The connecting bridge width is 8mm. The magnetic core surface is coated with a 1mm thick insulating and thermally conductive coating, and three PT100 sensors are embedded within. A 100-turn miniature Rogowski coil (0.05mm wire diameter) is installed in the connecting bridge recess. The coil unit uses a 6-layer 2oz copper thick PCB coil, with 8 turns per phase winding, a wire width of 2mm, and a wire spacing of 0.5mm. The total coil thickness is 1.6mm. The terminal interface is a pluggable connector with a 0402 packaged matching element. The capacitor compensation network is 4-bit digitally adjustable, with a capacitance adjustment range of 0-1110pF (in 10pF steps). Initial calibration is performed at a 50kHz test frequency.

[0029] The inductor's common-mode inductance at a rated current of 30A, measured at 25℃, is 15mH ± 2% (three-phase deviation), and its self-resonant frequency (SRF) is greater than 8MHz. Under full-load operation of the inverter and a switching frequency of 16kHz, the three-phase flux imbalance can be continuously controlled to <2% through dynamic adjustment by the phase balancing module. Combined with external capacitors, this ensures the inverter has at least a 6dB margin in conducted interference tests within the 150kHz-30MHz frequency band.

[0030] This invention provides a comparative example: (1) This comparative example sets up two comparative examples to compare and verify the present invention, wherein: Comparative Example 1 uses traditional technology, employing a toroidal ferrite core (outer diameter 45mm, inner diameter 25mm, height 15mm, equivalent PC95 material) to manually wind three-phase enameled round wire (1.2mm diameter) coils, 25 turns per phase. It lacks any balance monitoring or compensation function. Comparative Example 2 uses an improved technique, employing UI-type ferrite cores pieced together to form a three-column magnetic circuit, and winding flat copper wire coils. The three-phase windings are wound separately and then assembled, relying on initial calibration to ensure consistency, without online dynamic compensation capability. This invention is verified using Example 1.

[0031] In this experiment, under the test conditions of 25℃, 1Vrms, and 10kHz, the inductance L and DC resistance DCR of the three-phase neutral point were measured using a precision LCR meter, as shown in Table 1.

[0032] Table 1 Comparison of consistency of three-phase parameters

[0033] As shown in the table above, the maximum deviation of inductance in Example 1 is only 0.1%, with a standard deviation as low as 0.01mH, and the maximum deviation of DC resistance is only 0.2%, with a standard deviation of 0.06mΩ. These indicators are significantly better than those of Comparative Example 1, which relies on manual winding and has weak consistency control (maximum deviations of inductance and resistance reach 4.4% and 5.3%, respectively). They also significantly exceed those of Comparative Example 2, which, although improved, still relies on static adjustment (maximum deviations of 0.9% and 0.8%, respectively). This demonstrates that the racetrack-shaped magnetic core combined with the design of a precision structured flat coil and the online testing and data feedback system throughout the manufacturing process adopted in this invention can ensure the symmetry of the three-phase windings, thereby enabling the common-mode inductor to achieve excellent and stable filtering performance.

[0034] (2) In this experiment, the inductor under test is connected to the standard circuit, and its S21 parameter (converted to insertion loss) in a 50Ω system is measured using a network analyzer. The test is carried out under a rated current of 10A DC bias, as shown in Table 2.

[0035] Table 2 Comparison of Common-Mode Insertion Loss Frequency Characteristics

[0036] As shown in the table above, Example 1 exhibits the best noise suppression capability across the entire test frequency band (150kHz to 10MHz), especially in the high-frequency range above 1MHz, where the advantage is even greater. For example, at 10MHz, the insertion loss of Example 1 (-16.0dB) is improved by approximately 5.2dB and 0.9dB compared to Comparative Example 1 (-10.8dB) and Comparative Example 2 (-15.1dB), respectively, demonstrating that the structured flat coil and symmetrical magnetic circuit design adopted in this invention effectively improves high-frequency characteristics. After enabling dynamic compensation, the insertion loss of Example 1 still shows a slight improvement at most frequency points (e.g., from -16.0dB to -16.8dB at 10MHz), proving that the integrated phase balance module can fine-tune performance online.

[0037] (3) The three samples were placed in a high temperature environment of 85°C and a 20A RMS AC current (50Hz) was continuously applied for accelerated aging for 1000 hours. The samples were cooled to 25°C every 100 hours and their common mode insertion loss and three-phase imbalance at 500kHz were tested, as shown in Table 3.

[0038]

[0039] As shown in the table above, during the aging process of up to 1000 hours, the performance of Comparative Example 1 showed a sharp and uncontrollable decline, with its insertion loss decreasing by 4.0 dB and its three-phase imbalance deteriorating to 9.5%. Although Comparative Example 2 showed some improvement, it still showed a clear linear decline trend. Example 1, with its integrated phase balancing module and dynamic compensation mechanism, successfully suppressed the decline of effective insertion loss to an extremely low level of less than 0.3 dB and actively and stably maintained the three-phase imbalance below 1%.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil, characterized in that, Including: The magnetic core unit uses nanocrystalline or ferrite materials with high magnetic permeability and low loss. The magnetic core unit contains at least two parallel racetrack-shaped magnetic cores, which are integrally formed by connecting bridges to form multiple parallel independent magnetic circuit channels. The coil unit includes three flat Litz wire windings corresponding to the three-phase circuit. Each winding is wound on the magnetic circuit channel at a predetermined interval and angle. The lead-out end of each winding is provided with a high-frequency adaptive terminal interface. A phase balance module, integrated inside or on the surface of the core unit, includes a distributed capacitor compensation network and a flux detection coil, used to monitor and adjust the flux balance state of the three-phase winding in real time. An integrated test interface is located in the system casing and communicates with the phase balance module and external test equipment to collect inductance, leakage inductance, common-mode impedance and temperature rise parameters online. The adaptive control unit, based on real-time data from the test interface, dynamically optimizes the common-mode rejection characteristics of the device over a wide frequency range by adjusting the capacitance of the capacitor compensation network or connecting a parallel damping resistor.

2. The three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil according to claim 1, characterized in that: The cross-section of the racetrack-shaped magnetic core is rectangular or elliptical, with its long side arranged parallel to the wide side of the flat coil. The surface of the magnetic core is covered with an insulating and thermally conductive coating, and a distributed temperature sensor is embedded in the coating.

3. A three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil according to claim 1, characterized in that: The flat Litz wire winding adopts a multi-layer PCB printed coil or flat copper wire vertical winding structure, with polyimide insulation layers between each layer, and the winding ends are connected to high-frequency adaptive terminal interfaces by laser welding.

4. A three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil according to claim 1, characterized in that: The phase balancing module includes a digital signal processor that receives the induced signal from the flux detection coil and performs real-time phase calibration through an adjustable capacitor array in the capacitor compensation network.

5. A three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil according to claim 1, characterized in that: The integrated test interface supports multiple communication protocols, including SPI, IIC or CAN bus, and can upload monitoring data to external quality management systems or production execution systems in real time.

6. An apparatus for fabricating a three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil, as described in any one of claims 1-5, characterized in that, Including: An automatic feeding and positioning mechanism for magnetic cores is used to transport racetrack-shaped magnetic cores to the assembly station. The coil winding and welding unit, including a multi-axis robotic arm and a vision positioning system, is used to wind flat coils into a magnetic core and complete terminal welding. The phase balance module mounting module uses high-precision dispensing and patch technology to integrate the capacitor compensation network and the magnetic flux detection coil into a predetermined position on the magnetic core. The online integrated test station integrates an LCR tester, a network analyzer, and a thermal imager to simultaneously test the electrical and thermal performance of assembled products. The data feedback system records the test data of each product and compares it with the design parameters, automatically adjusting the winding tension, welding parameters or mounting position to compensate for deviations.

7. The apparatus for preparing a three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil according to claim 6, characterized in that: In the coil winding and welding unit, the winding head has a tension adaptive control function, which can adjust the winding tension in real time according to the width and thickness of the flat wire.

8. The apparatus for preparing a three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil according to claim 6, characterized in that: The online integrated testing station also includes an aging test module, which can perform cyclic power-on tests on the product in a high temperature and high humidity environment and record performance degradation data.

9. The apparatus for preparing a three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil according to claim 6, characterized in that: The data feedback system analyzes historical production data through machine learning algorithms to predict and optimize process parameters, thereby achieving adaptive process adjustment.

10. The apparatus for preparing a three-phase common-mode inductor with a racetrack-shaped magnetic core and a flat coil according to claim 6, characterized in that: The device also includes a three-dimensional optical inspection unit, which is used to perform three-dimensional scanning on the assembled product and compare it with the digital twin model to detect whether the structural dimensions and assembly accuracy meet the design requirements.

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