Three-phase LLC charging module based on magnetic integration

Abstract

The invention relates to the technical field of power electronic conversion, and discloses a three-phase LLC charging module based on magnetic integration, which comprises an input EMI filter circuit, a PFC power factor correction circuit, a three-phase LLC main power circuit, an output anti-reverse connection circuit and a controller. The three-phase LLC main power circuit comprises a primary side switch network, a resonant capacitor network and a three-phase integrated magnetic part; the three-phase integrated magnetic piece adopts a three-column closed magnetic core structure, and a preset leakage inductance value is generated by arranging an insulating interlayer or a gap; the circuit does not contain an independent discrete resonant inductor element, but directly uses the leakage inductance value as a resonant inductor to be matched with a resonant capacitor network to form a resonant circuit. The loss is reduced by using a magnetic flux counteracting principle, and PFM control is performed based on a voltage gain model. The circuit structure is simplified through the magnetic integration technology, high power density and miniaturization are achieved, and meanwhile the active reverse connection prevention and soft start protection functions are achieved.

Description

Technical Field

[0001] This invention relates to the field of power electronic conversion technology, specifically a three-phase LLC charging module based on magnetic integration. Background Technology

[0002] With the booming development of the new energy electric vehicle industry, the power density and conversion efficiency of high-power charging modules, as core infrastructure, have become key indicators for measuring technological level. Among various power conversion topologies, LLC resonant converters are widely used in high-power DC charging equipment because they can achieve zero-voltage turn-on (ZVS) of the primary-side switch and zero-current turn-off (ZCS) of the secondary-side rectifier diodes across the entire load range, thereby reducing switching losses and improving electromagnetic compatibility performance.

[0003] However, in traditional three-phase LLC resonant converter designs for high-power applications, the layout and structure of magnetic components are typically complex and bulky. Current mainstream solutions often employ a discrete magnetic component architecture, requiring three independent single-phase transformers and three independent discrete resonant inductors to construct the three-phase resonant circuit. This discrete physical architecture results in a large number of magnetic components, occupying significant physical space on the PCB and within the chassis, severely limiting the overall power density of the charging module. Furthermore, the use of multiple independent magnetic cores prevents the utilization of the flux cancellation effect unique to three-phase AC systems, leading to a larger overall core size, higher hysteresis and eddy current losses, and consequently, difficulties in heat dissipation and excessive temperature rise. In addition, the numerous connection points of discrete components increase the complexity of the assembly process and production costs.

[0004] On the other hand, existing system designs also have limitations in terms of safety protection and startup control when it comes to the practical application and control strategies of charging modules. For example, when connecting the output terminal to the battery load, traditional solutions often lack a robust active reverse connection identification and isolation mechanism. Once the battery polarity is reversed, it can easily cause a short circuit in the downstream capacitor or even lead to a battery explosion. Simultaneously, at the moment of converter startup, without a refined soft-start frequency scanning strategy, a large inrush current can easily be generated, causing electrical stress damage to power semiconductor devices and affecting the long-term reliability and stability of the charging module under complex operating conditions. Therefore, how to optimize the circuit structure through magnetic integration technology and coordinate it with robust control and protection logic has become a pressing technical challenge in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a three-phase LLC charging module based on magnetic integration, which solves the problems of large magnetic component size, low power density, high magnetic loss, and insufficient system integration caused by the use of discrete transformers and resonant inductors in existing high-power charging modules.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a three-phase LLC charging module based on magnetic integration, including an input EMI filter circuit, a PFC power factor correction circuit, a three-phase LLC main power circuit, an output EMI filter circuit, an output reverse polarity protection circuit, and a controller. The input EMI filter circuit receives three-phase AC power input and filters out electromagnetic interference. The PFC power factor correction circuit is connected to the output of the input EMI filter circuit, converting the AC power into high-voltage DC power and establishing a DC bus voltage. The three-phase LLC main power circuit is connected to the DC bus voltage and inverts the DC power into high-frequency AC power for resonant conversion. The output EMI filter circuit and the output reverse polarity protection circuit are sequentially connected to the output of the three-phase LLC main power circuit, respectively filtering out high-frequency interference signals on the output side and preventing reverse polarity connection. The controller establishes signal connections with the PFC power factor correction circuit, the three-phase LLC main power circuit, and the output reverse polarity protection circuit to achieve closed-loop control and protection of the system.

[0007] The three-phase LLC main power circuit includes a primary-side switching network, a resonant capacitor network, a three-phase integrated magnetic component, and a secondary-side rectifier network. The resonant capacitor network contains discrete capacitors connected in series in the primary-side circuit. The core of this invention lies in the magnetic integration design, where the primary and secondary windings of the three-phase integrated magnetic component have a preset leakage inductance value. The three-phase LLC main power circuit eliminates the need for independent discrete resonant inductors, directly utilizing the leakage inductance value of the three-phase integrated magnetic component as the resonant inductor. This leakage inductance value, in conjunction with the resonant capacitor network, forms a resonant circuit, thereby achieving integrated transformation of the transformer and the resonant inductor.

[0008] Furthermore, the PFC power factor correction circuit adopts a three-phase Vienna rectifier topology. This topology includes boost inductors connected in series on each phase input line, a bidirectional switching network connected between each phase input line and the midpoint of the DC bus, and a rectifier diode network connected between each phase input line and the positive and negative DC buses. The DC bus voltage is composed of an upper voltage divider capacitor and a lower voltage divider capacitor connected in series. The common terminal of the bidirectional switching network is connected to the midpoint of the connection between the upper and lower voltage divider capacitors, thereby achieving three-level rectification and power factor correction.

[0009] Regarding the connection and control of the three-phase LLC main power circuit, the primary-side switching network consists of three parallel half-bridge arms (A-phase, B-phase, and C-phase), with the midpoint of each arm serving as the output terminal. One end of the capacitor in the resonant capacitor network is connected to the midpoint of the corresponding arm, and the other end is connected to the primary winding input terminal of the corresponding phase of the three-phase integrated magnetic component. The controller sends pulse-frequency modulated drive signals to the primary-side switching network and strictly controls the phase difference between the drive signals of the A-phase, B-phase, and C-phase arms to be 120 degrees.

[0010] The physical structure and working principle of a three-phase integrated magnetic component are described, including a closed magnetic core assembly and a winding assembly. The closed magnetic core assembly adopts a three-column structure, including a first, second, and third magnetic column arranged in parallel, and an upper and lower magnetic yoke laterally connected across the two ends of the three magnetic columns. The winding assembly includes three sets of windings: the primary and secondary windings of phases A, B, and C are coaxially wound on the corresponding first, second, and third magnetic columns, respectively.

[0011] To achieve integration and magnetic circuit decoupling of the resonant inductor, insulating layers or physical gaps of predetermined thickness are provided between the primary and secondary windings on the first, second, and third magnetic pillars. This reduces the coupling coefficient between the primary and secondary windings, thereby generating the required leakage inductance value. During operation, when excitation currents with a 120-degree phase difference are applied to the three-phase primary windings, the magnetic flux generated by the three magnetic pillars is vector-superimposed at the upper and lower yokes. Based on the principle of three-phase symmetry, the algebraic sum of the AC magnetic flux in the common magnetic circuit approaches zero, achieving flux cancellation and magnetic circuit decoupling, reducing core losses, and preventing magnetic saturation.

[0012] For input-level protection, the input EMI filter circuit includes a two-stage common-mode filter unit consisting of a first-stage common-mode inductor, a second-stage common-mode inductor, and X and Y capacitor banks, as well as a soft-start unit connected to its output side. The soft-start unit includes a current-limiting resistor and a bypass relay connected in parallel with it. The bypass relay closes after the DC bus voltage is established to short-circuit the current-limiting resistor and prevent power-on surge.

[0013] For output stage protection, the output reverse connection protection circuit includes a relay assembly or power semiconductor switch assembly connected in series on the positive DC output bus, along with an output sampling feedback unit. The controller executes active reverse connection protection logic: it detects the polarity of the output voltage before the relay assembly closes; if the detected voltage polarity is negative, it locks the relay assembly in the open state; it only allows the relay assembly to close when the detected voltage polarity is correct or there is no voltage, thereby protecting the downstream circuitry and load.

[0014] In terms of secondary-side rectification, the secondary-side rectifier network is connected to the secondary winding of the three-phase integrated magnet, employing a full-wave rectification structure or a center-tapped rectification structure to rectify the three-phase high-frequency AC power into pulsating DC power. The pulsating DC power converges at the DC bus and high-frequency ripple is filtered out by a parallel output filter capacitor bank.

[0015] In terms of control strategy, the controller performs pulse frequency modulation control based on the voltage gain model of the three-phase LLC converter. This voltage gain model is a function of the normalized switching frequency, inductance ratio, and quality factor. The controller collects the actual output voltage and output current, compares them with the target reference, and dynamically adjusts the switching frequency to stabilize the output by utilizing the negative gain slope characteristic of the voltage gain model in the inductive operating region. In addition, the controller also implements a soft-start control strategy, controlling the primary-side switching network to operate at a preset maximum switching frequency at the moment of startup, and then controlling the switching frequency to decrease from the maximum switching frequency to the operating frequency point at a preset slope until the output voltage reaches the closed-loop stable point, thus achieving a smooth start.

[0016] This invention provides a three-phase LLC charging module based on magnetic integration. It has the following advantages: 1. This invention utilizes a three-phase integrated magnetic component structure design to artificially control the insulation layer or gap between the primary and secondary windings to generate a preset leakage inductance, which is then directly used as the resonant inductor required for the LLC resonant circuit. This design eliminates the bulky independent discrete resonant inductor components found in traditional solutions, reduces the number of magnetic components, optimizes PCB layout space, thereby increasing the power density of the charging module and reducing the system size.

[0017] 2. This invention employs a three-column closed magnetic core structure combined with a drive control with a 120-degree phase difference, enabling the three-phase AC magnetic flux to undergo vector superposition and cancellation in the common yoke section. This flux cancellation effect significantly reduces the net magnetic flux density in the common magnetic circuit section, reduces hysteresis loss and eddy current loss of the magnetic core, and lowers the temperature rise of the magnetic components, thereby improving the overall conversion efficiency of the converter.

[0018] 3. This invention combines output reverse connection protection logic with a frequency scanning soft-start strategy. By detecting the polarity of the output voltage before the relay closes, it prevents short-circuit damage caused by reverse battery connection; at the same time, by using a soft-start method that scans from the high frequency to the operating frequency, it suppresses the large current surge at startup, ensuring the safe operation of power devices under complex operating conditions. Attached Figure Description

[0019] Figure 1 This is a system principle block diagram of the present invention; Figure 2 This is a schematic diagram of the physical structure of the three-phase integrated magnetic component of the present invention; Figure 3This is a schematic diagram of the three-phase LLC main circuit topology of the present invention; Figure 4 This is a schematic diagram of the output control and protection circuit of the present invention; Figure 5 This is the schematic diagram of the APFC main circuit of the present invention; Figure 6 This is a detailed schematic diagram of the DC-DC main circuit of the present invention; Figure 7 This is a schematic diagram of the input EMI and soft-start circuit of the present invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0021] See attached document Figure 1 The present invention provides a charging module using three-phase LLC integrated magnetic technology, which includes: an input EMI filter circuit 10, a PFC power factor correction circuit 20, a three-phase LLC main power circuit 30, an output reverse connection protection circuit 40, an output EMI filter circuit 50, and a controller 60.

[0022] The input terminal of the input EMI filter circuit 10 is connected to a three-phase AC power supply to receive the three-phase AC input voltage. The output terminal of the input EMI filter circuit 10 is electrically connected to the input terminal of the PFC power factor correction circuit 20. The input EMI filter circuit 10 is equipped with a common-mode inductor and a safety capacitor to suppress high-frequency interference signals from the power grid from entering the charging module and to suppress interference signals generated inside the charging module from being fed back to the power grid.

[0023] The output of the PFC power factor correction circuit 20 is electrically connected to the input of the three-phase LLC main power circuit 30. The PFC power factor correction circuit 20 is configured to convert the filtered three-phase AC power into high-voltage DC power and establish a stable DC bus voltage. The PFC power factor correction circuit 20 corrects the power factor by controlling the on and off states of the switching transistor to make the phase of the input current follow the phase of the input voltage.

[0024] The input terminal of the three-phase LLC main power circuit 30 is connected to the DC bus voltage. Its output terminal is electrically connected to the input terminal of the output reverse connection protection circuit 40. The three-phase LLC main power circuit 30 includes a primary-side switching network, a resonant network, three-phase integrated magnetic components, and a secondary-side rectifier network. The primary-side switching network converts the DC bus voltage... The voltage is inverted into a three-phase high-frequency AC square wave voltage. The controller 60 sends a drive signal to the primary-side switching network, causing the three-phase high-frequency AC square wave voltages to be 120 degrees out of phase.

[0025] Define the switching frequency as The time is Then, the phases of the driving voltages of phases A, B, and C in the three-phase LLC main power circuit 30 are... , , They respectively satisfy the following relations: ; ; ; The resonant network in the three-phase LLC main power circuit 30 includes a resonant capacitor. and resonant inductor Resonant capacitor It is an independent discrete capacitor element, connected in series in the primary circuit. Resonant inductor. It is not a separate, independent inductor element, but rather the leakage inductance between the primary and secondary windings of a three-phase integrated magnetic component. Composition, that is The resonant frequency of the resonant network Defined by the following formula: ; in, This represents the equivalent resonant inductance value provided by the integrated magnetic component. This represents the value of the series resonant capacitor. Pi is the mathematical constant of a circle.

[0026] The three-phase integrated magnetic component includes three magnetic pillars and a yoke connecting them. The primary and secondary windings of phases A, B, and C are wound on their respective magnetic pillars. Through the coupling and decoupling of the three-phase magnetic circuit, the three-phase integrated magnetic component converts the high-voltage electrical energy on the primary side into low-voltage electrical energy on the secondary side, achieving electrical isolation. The secondary rectifier network is connected to the secondary winding of the three-phase integrated magnetic component, rectifying the induced high-frequency alternating current into pulsating direct current.

[0027] The output reverse connection protection circuit 40 is connected between the output terminal of the three-phase LLC main power circuit 30 and the input terminal of the output EMI filter circuit 50. The output reverse connection protection circuit 40 includes a relay assembly or a power semiconductor switching assembly. The output reverse connection protection circuit 40 is configured to detect the polarity of the load terminal; when the load polarity matches the output polarity, the circuit is turned on to allow current output; when the load polarity is reversed, the circuit is turned off to block the current path.

[0028] The input terminal of the output EMI filter circuit 50 is connected to the output reverse connection protection circuit 40, and its output terminal is connected to the load. The output EMI filter circuit 50 is used to filter out high-frequency ripple and noise in the DC output, ensuring the output voltage... and output current It improves stability and suppresses electromagnetic interference.

[0029] The controller 60 is electrically connected to the primary-side switching network of the PFC power factor correction circuit 20, the three-phase LLC main power circuit 30, and the output reverse connection protection circuit 40. The controller 60 collects the output voltage. and output current The sampling signal is used to adjust the switching frequency according to a preset constant voltage or constant current control algorithm. This controls the voltage gain of the three-phase LLC main power circuit 30, thereby regulating the output voltage or output current.

[0030] See attached document Figure 2 Appendix Figure 5 and attached Figure 7 The specific implementations of the input EMI filter circuit 10 and the PFC power factor correction circuit 20 provided by the present invention are as follows: The input EMI filter circuit 10 includes an input protection unit 11, a two-stage common-mode filter unit 12, and a soft-start unit 13. The input protection unit 11 is located between the three-phase AC power input terminals (U, V, W) and the two-stage common-mode filter unit 12. The input protection unit 11 includes fuses (F2, F3, F4) connected in series on each phase input line, and varistors (RV4, RV5, RV6) connected in parallel between each phase input line and between each phase input line and ground. The varistors are configured to clamp the voltage when the input voltage is overvoltage, and the fuses are configured to disconnect the physical connection when the current is overloaded. Additionally, a gas discharge tube (DG1) is connected between the protective ground and the power ground to discharge lightning surge energy.

[0031] The two-stage common-mode filter unit 12 includes a first-stage common-mode inductor (L5) and a second-stage common-mode inductor (L6) connected sequentially along the current transmission direction. X capacitor banks (CX1 to CX14) are connected across the front and rear ends of the first-stage common-mode inductor (L5) and the rear end of the second-stage common-mode inductor (L6) respectively to filter differential-mode interference. Y capacitor banks (CY12 to CY23) are connected between the input line and protective ground to filter common-mode interference.

[0032] The soft-start unit 13 is connected to the output side of the two-stage common-mode filter unit 12. The soft-start unit 13 includes a current-limiting resistor (RT) and bypass relays (RLY3, RLY4) connected in parallel with the current-limiting resistor. During the initial power-on phase, the bypass relays are open, and the input current flows through the current-limiting resistor to pre-charge the subsequent capacitor. When the voltage of the subsequent stage reaches a preset threshold, the bypass relays close, short-circuiting the current-limiting resistor, and the system enters a low-impedance shoot-through state. The output terminals (U2, V2, W2) of the soft-start unit 13 are connected to the PFC power factor correction circuit 20.

[0033] The PFC power factor correction circuit 20 adopts a three-phase Vienna rectifier topology, including a PFC inductor group 21, a bidirectional switching network 22, a rectifier diode network 23, and a DC bus capacitor group 24.

[0034] The PFC inductor group 21 includes boost inductors (L1, L2, L3) connected in series on the three-phase input lines U2, V2, and W2, respectively. The boost inductors are used to store energy and work with the switching transistors to achieve voltage boosting. Current sampling resistors (R53, R66, R77) are connected in series between the boost inductors and the subsequent switching network to collect the input current signals of each phase in real time and feed them back to the controller.

[0035] The rectifier diode network 23 includes six fast recovery diodes (D18 to D23). Taking phase U as an example, the anode of the first diode (D18) is connected to the phase U line, and the cathode is connected to the positive DC bus (+Vpfc); the cathode of the second diode (D21) is connected to the phase U line, and the anode is connected to the negative DC bus (-Vpfc or PGND). Phase V and phase W have the same diode connection structure, consisting of diodes D19 and D22, and D20 and D23, respectively.

[0036] A bidirectional switching network 22 is connected between the midpoint of each phase line and the DC bus. Taking phase U as an example, the bidirectional switching network consists of two source-to-source MOSFETs (Q13, Q14). The drain of the first MOSFET (Q13) is connected to the phase U line (located between the boost inductor L1 and the rectifier diode network 23), and the drain of the second MOSFET (Q14) is connected to the midpoint of the DC bus. The gates of the first MOSFET (Q13) and the second MOSFET (Q14) are connected to the drive signal terminals (DRV_Us, DRV_Ug1, etc.) through the gate drive resistor network, respectively. The bidirectional switching networks for phases V and W are constructed in the same manner using MOSFET pairs (Q15, Q16) and (Q17, Q18), respectively.

[0037] The DC bus capacitor bank 24 includes upper voltage divider capacitors (C57, C56) and lower voltage divider capacitors (C79, C80) connected in series between the positive DC bus (+Vpfc) and the negative DC bus (PGND / -Vpfc). The connection point of the upper and lower voltage divider capacitors forms the midpoint of the DC bus and is connected to the common terminal of the bidirectional switching network 22. The PFC power factor correction circuit 20 converts the input three-phase AC power into a DC bus voltage with positive, negative, and midpoint potentials by controlling the on and off duty cycles of the bidirectional switching network 22.

[0038] See attached document Figure 2 and attached Figure 3 The three-phase LLC main power circuit 30 of the present invention specifically includes a primary-side switching network 31, a resonant capacitor network 32, and a secondary-side rectifier and filter network 33.

[0039] The primary-side switch network 31 adopts a three-phase half-bridge topology, with its DC input terminals connected to the positive DC bus (+Vpfc) and the negative DC bus (PGND), respectively. The primary-side switch network 31 consists of three parallel half-bridge arms, namely phase A arm, phase B arm, and phase C arm.

[0040] Phase A bridge arm is composed of a first power switch (Q1) and a second power switch (Q2) connected in series. The drain of the first power switch (Q1) is connected to the positive DC bus, and the source is connected to the drain of the second power switch (Q2) to form the midpoint of phase A bridge arm (DRV_Ag / As). The source of the second power switch (Q2) is connected to the negative DC bus.

[0041] The B-phase bridge arm is composed of the third power switch (Q3) and the fourth power switch (Q5) connected in series, with the midpoint being the midpoint of the B-phase bridge arm (DRV_Cg / Cs).

[0042] The C-phase bridge arm is composed of the fifth power switch (Q6) and the sixth power switch (Q7) connected in series, with the midpoint being the midpoint of the C-phase bridge arm (DRV_Eg / Es).

[0043] The gate of each power switch is connected to the corresponding gate drive circuit to receive PFM drive pulses with a phase difference of 120 degrees from the controller.

[0044] The resonant capacitor network 32 includes a first resonant capacitor group (C6-C13, C19, C26, C31), a second resonant capacitor group (C23, C28-C30, C32-C34, C41, C49), and a third resonant capacitor group (C45, C50-C56, C63, C65) corresponding to the three phases A, B, and C, respectively.

[0045] One end of the first resonant capacitor bank is directly connected to the midpoint of the A-phase bridge arm, and the other end is directly connected to the input terminal (T1Pin3) of the A-phase primary winding of the three-phase integrated magnet.

[0046] One end of the second resonant capacitor bank is directly connected to the midpoint of the B-phase bridge arm, and the other end is directly connected to the input terminal (T2Pin3) of the B-phase primary winding of the three-phase integrated magnet.

[0047] One end of the third resonant capacitor bank is directly connected to the midpoint of the C-phase bridge arm, and the other end is directly connected to the input terminal (T3Pin3) of the C-phase primary winding of the three-phase integrated magnet.

[0048] In this embodiment, no independent discrete inductors are connected in series on the current transmission path between the primary-side switching network 31 and the primary winding of the three-phase integrated magnet, except for the resonant capacitor network 32. The inductance required for the resonant circuit is entirely provided by the internal leakage inductance of the subsequently connected three-phase integrated magnet. The tail ends (T1Pin4, T2Pin4, T3Pin4) of the A, B, and C primary windings of the three-phase integrated magnet are connected to a common neutral point or to the corresponding loop ground, forming a Y-type connection or an independent loop structure.

[0049] The secondary-side rectifier and filter network 33 is configured on the secondary output side of the three-phase integrated magnet. The secondary winding of the three-phase integrated magnet adopts a center-tapped structure or a full-wave rectifier structure.

[0050] Taking phase A as an example, the secondary rectifier unit of phase A includes a first rectifier diode (D1) and a second rectifier diode (D3). The first end (T1Pin1) of the secondary winding of phase A is connected to the anode of the first rectifier diode (D1), and the second end (T1Pin3) of the secondary winding of phase A is connected to the anode of the second rectifier diode (D3). The cathodes of the first rectifier diode (D1) and the second rectifier diode (D3) are connected to the DC output positive network (VO+). The center tap (T1Pin2) of the secondary winding of phase A is connected to the output ground network (AGND).

[0051] The B-phase secondary rectifier unit (including diodes D12 and D14) and the C-phase secondary rectifier unit (including diodes D22 and D24) are connected to the B-phase and C-phase secondary windings and the DC output positive network respectively with the same circuit structure.

[0052] The secondary-side rectifier filter network 33 also includes an output filter capacitor bank (EC2-EC10, EC13-EC21, EC23-EC31). The output filter capacitor bank is connected in parallel between the DC output positive network (VO+) and the output ground network (AGND) to filter out the high-frequency ripple generated by the superposition of the three-phase rectified current and generate a smooth DC output voltage.

[0053] The core of this invention, the three-phase integrated magnetic component, adopts magnetic integration technology to integrate a three-phase transformer and three resonant inductors into one physical space.

[0054] The three-phase integrated magnetic component is mainly composed of a closed magnetic core assembly and a winding assembly in terms of physical structure. The closed magnetic core assembly uses a low-loss power ferrite material (such as manganese-zinc ferrite) and has a three-column geometry, specifically including a first, second, and third magnetic column arranged in parallel, and an upper and lower yoke located at the top and bottom, respectively. The upper and lower yokes are laterally connected across the two ends of the three magnetic columns, thereby forming a low-resistivity closed magnetic path between the first, second, and third magnetic columns.

[0055] The winding assembly includes three independent coils corresponding to phases A, B, and C. The primary and secondary windings of phase A are both wound on the first magnetic post; the primary and secondary windings of phase B are both wound on the second magnetic post; and the primary and secondary windings of phase C are both wound on the third magnetic post. The primary and secondary windings of each phase are arranged coaxially in lap or segmented windings on their respective magnetic posts.

[0056] This embodiment achieves the integration of resonant inductors through winding technology and magnetic circuit design. Specifically, on each magnetic post, the primary and secondary windings are not tightly bonded, but rather have an insulating layer or physical gap of predetermined thickness, or distributed air gaps are provided in the magnetic circuit. This structural design artificially reduces the coupling coefficient between the primary and secondary windings, forcing a portion of the magnetic flux generated by the primary winding to be unable to couple to the secondary winding, but instead closing through air or leakage flux paths to form leakage flux.

[0057] The leakage flux exhibits electrical characteristics as a series leakage inductance in the primary winding ( Since the independent discrete resonant inductor is eliminated in the three-phase LLC circuit of this scheme, the primary leakage inductance directly serves as the resonant inductor required for the LLC resonant circuit. By precisely adjusting the spacing, number of turns, or air gap length of the primary and secondary windings, the leakage inductance value can be precisely controlled within the range of resonant inductance parameters required by the design (e.g., controlled at the microhenry level), thereby realizing the integration of the transformer and the resonant inductor.

[0058] During operation, this structure achieves the crucial functions of flux cancellation and decoupling. When high-frequency excitation currents with a phase difference of 120 degrees are applied to the primary windings of phases A, B, and C, three-phase alternating magnetic fluxes that vary with time are generated in the first, second, and third magnetic columns, respectively. , and .

[0059] These three-phase magnetic fluxes undergo vector superposition as they flow through the common magnetic circuit portion of the upper and lower yokes. Based on the principle of symmetry in three-phase AC systems, under ideal equilibrium conditions, the vector sum of the three-phase magnetic fluxes approaches zero at any given moment, i.e.: ; This flux cancellation effect significantly reduces the net flux density of the common yoke. Compared to the three independent discrete transformer schemes, the yoke in this scheme no longer needs to withstand the superposition of all the single-phase flux. Therefore, the cross-sectional areas of the upper and lower yokes can be designed to be smaller, or the core loss and temperature rise can be reduced while keeping the cross-sectional area constant.

[0060] Furthermore, the three-column structure ensures that the magnetic flux of each phase is primarily closed between its own column and adjacent columns, achieving relative independence of energy transfer between phases through phase difference, i.e., magnetic decoupling. This guarantees that the three-phase LLC circuits do not interfere with each other during independent resonant transformations and can maintain their own stable voltage gain characteristics.

[0061] See attached document Figure 4 and attached Figure 6 In this embodiment, the secondary output control and protection circuit is located after the secondary rectifier network of the three-phase integrated magnetic component, and mainly consists of a DC bus, an output on / off control unit, an isolation drive unit, and an output sampling feedback unit.

[0062] The DC busbar includes a positive bus (VO+) and a negative bus (AGND). The pulsating DC currents from the three secondary rectifier units (phases A, B, and C) physically converge at the positive and negative busbars. The positive busbar is connected to the input terminal of the output on / off control unit. A high-frequency filter capacitor bank is also connected in parallel at this busbar to absorb high-frequency switching noise and establish a stable DC potential.

[0063] The output on / off control unit is connected in series between the positive bus and the final output terminal (RLY+ / BAT+). This unit uses a group of high-power relays connected in parallel (RLY1, RLY2, RLY3, RLY4) as the main actuators. The contacts of the multiple relays are connected in parallel to shunt large currents, reduce heat loss from contact resistance of individual contacts, and improve the current carrying capacity of the system.

[0064] The isolation drive unit is used to connect the low-voltage side controller and the high-voltage side relay. This unit includes optocouplers (U25, U5, etc.) and drive transistors (Q19, Q20).

[0065] The primary-side LED of the optocoupler is connected to the GPIO output of the controller (DCDC_RLY_DRV), and the secondary-side phototransistor is connected to the base of the driver transistor. When the controller issues a closing command, the optocoupler conducts, the driver transistor saturates and conducts, thereby connecting the power supply circuit (12VS1) of the relay coil, causing the relay contacts to close.

[0066] Conversely, when the controller cancels the command or detects a fault, the drive transistor is cut off, the relay coil is de-energized, and the contacts open under the action of the mechanical spring, cutting off the output circuit.

[0067] A freewheeling diode (D17, D21, D76, D77) is connected in reverse parallel across the two ends of each relay coil to absorb the reverse electromotive force generated by the coil when the relay is disconnected, preventing high voltage from damaging the drive transistor.

[0068] The output sampling feedback unit includes a current sampling resistor or Hall sensor connected to the negative bus path, and a voltage divider sampling circuit connected between the positive and negative buses.

[0069] The current sampling circuit (DCDC_Isense) converts the output high-current signal into a low-voltage analog signal (ISENSE+ / ISENSE-), which is then conditioned by an operational amplifier and sent to the controller. This signal has a dual function: first, it serves as a feedback variable for the constant current control loop; second, it serves as a criterion for overcurrent protection. When the current exceeds the safety threshold, the controller immediately shuts off the primary-side switching network and disconnects the output relay.

[0070] Based on the above hardware structure, this embodiment implements active reverse connection protection logic. In the system standby state and with the relay open, the controller pre-detects the voltage polarity at the output terminals through a voltage sampling circuit. If a negative voltage is detected at the output terminal (i.e., the battery's positive and negative terminals are reversed), the controller forcibly locks the relay in the open state and reports a reverse connection fault, thereby physically isolating the internal capacitors of the charging module from the reverse-connected battery and preventing short-circuit explosions. Only when the output voltage polarity is detected to be correct and the voltage amplitude is within the allowable range (or in a no-voltage, no-load state) will the controller allow the relay to close, initiating the charging process.

[0071] See attached document Figure 3 and attached Figure 4 This embodiment details how the controller drives the three-phase LLC main power circuit through precise algorithm logic to achieve high-precision regulation of the output voltage and current.

[0072] The controller (such as a digital signal processor (DSP) or microcontroller (MCU) integrates a high-precision enhanced pulse width modulation (ePWM) module. During operation, the controller first establishes a three-phase timing reference. The drive signal of phase A bridge arm is used as the phase zero reference. The controller, through internal counters and phase register settings, forces the drive signal of phase B bridge arm to lag behind phase A. (Right now (radian), forcing the C-phase bridge arm's drive signal to lead the A-phase. (Right now (Radians). Regardless of changes in the switching frequency, this 120-degree phase relationship is always strictly locked by the controller. This ensures that the magnetic flux in the three-phase integrated magnet always meets the vector cancellation condition, preventing core saturation.

[0073] To regulate the output voltage or current, the controller employs a pulse frequency modulation (PFM) control strategy. This strategy is based on the voltage gain characteristics of the LLC resonant converter. In this embodiment, the DC voltage gain of the three-phase LLC circuit... With normalized switching frequency The functional relationship between them is modeled as follows: ; In this mathematical model, the parameters are defined as follows: Normalized frequency, i.e., the current switching frequency With the natural resonant frequency of the resonant circuit The ratio; Inductance ratio, i.e., the primary magnetizing inductance of the integrated magnetic component. With leakage inductance (resonant inductance) The ratio; Quality factor, which reflects the severity of the load. This is the equivalent load impedance referred back to the primary side.

[0074] Based on the above model, the LLC converter operates in the inductive region (i.e., The region exhibits a negative gain slope characteristic: switching frequency The higher the voltage gain The smaller the value; the lower the switching frequency The lower (closer) Voltage gain The larger the value, the better. The controller utilizes this monotonic characteristic to construct a negative feedback closed-loop regulation mechanism.

[0075] The specific voltage and current regulation control process is as follows: The controller reads the output voltage sampling value in real time. and output current sampling value and compare them with the internally set target voltage reference. and target current reference Compare them.

[0076] The system is configured with two parallel control loops: a voltage loop (CVLoop) and a current loop (CCLoop). During the initial stage of battery charging, when the battery voltage is low, the current loop dominates. The controller calculates... and The error is controlled by outputting a frequency control quantity through a proportional-integral (PI) regulator. If the actual current... Less than the set value The controller reduces the switching frequency. This causes the operating point to move towards the resonant frequency. Moving the current increases gain and output current; conversely, moving it increases frequency.

[0077] As charging progresses, the battery voltage gradually increases. When the output voltage... Achieve target voltage reference At this time, the control logic automatically and smoothly switches to voltage loop dominance. The controller adjusts the frequency based on the voltage error to maintain a constant output voltage, and the current naturally decreases as the battery saturation level increases.

[0078] In addition, to prevent the large current surge during startup, the controller executes a frequency scanning strategy during the soft-start phase. At the instant the primary-side switching network is activated, the controller first outputs a preset maximum switching frequency (…). At this point, the circuit gain is at its lowest. Subsequently, the controller gradually reduces the switching frequency according to a preset slope, allowing the output voltage to build up smoothly until the closed-loop stable point is reached. This strategy of scanning from high frequency to low frequency effectively avoids start-up overshoot and protects power devices and integrated magnetic components.

Claims

1. A three-phase LLC charging module based on magnetic integration, characterized in that, include: The input EMI filter circuit is used to receive three-phase AC power input and filter out electromagnetic interference. The PFC power factor correction circuit is connected to the output terminal of the input EMI filter circuit and is used to convert AC power into high voltage DC power and establish DC bus voltage. The three-phase LLC main power circuit is connected to the DC bus voltage and is used to invert DC power into high-frequency AC power and perform resonant conversion. The three-phase LLC main power circuit includes a primary-side switching network, a resonant capacitor network, a three-phase integrated magnetic component, and a secondary-side rectifier network. An output EMI filter circuit is connected to the output terminal of the three-phase LLC main power circuit and is used to filter out high-frequency interference signals on the output side. The output reverse polarity protection circuit is connected to the output terminal of the output EMI filter circuit and is used to output DC power to the load and prevent the output polarity from being reversed. The controller is connected to the PFC power factor correction circuit, the three-phase LLC main power circuit, and the output reverse connection protection circuit, respectively. The three-phase integrated magnetic component has an insulating layer or physical gap of predetermined thickness between its primary and secondary windings to reduce the coupling coefficient between them and generate a preset leakage inductance value. The three-phase LLC main power circuit does not contain independent discrete resonant inductor components, but directly uses the leakage inductance value as a resonant inductor to form a resonant circuit in conjunction with the resonant capacitor network.

2. The three-phase LLC charging module based on magnetic integration according to claim 1, characterized in that, The PFC power factor correction circuit adopts a three-phase Vienna rectifier topology. The topology includes a boost inductor connected in series with each phase input line, a bidirectional switching network connected between each phase input line and the midpoint of the DC bus, and a rectifier diode network connected between each phase input line and the positive and negative DC buses. The DC bus voltage is composed of an upper voltage divider capacitor and a lower voltage divider capacitor connected in series, and the common terminal of the bidirectional switching network is connected to the midpoint of the connection between the upper voltage divider capacitor and the lower voltage divider capacitor.

3. A three-phase LLC charging module based on magnetic integration according to claim 1, characterized in that, The connection method of the three-phase LLC main power circuit is as follows: The primary-side switching network consists of three parallel half-bridge arms, namely phase A, phase B, and phase C, with the midpoint of each arm serving as the output terminal. One end of the capacitor in the resonant capacitor network is connected to the midpoint of the corresponding bridge arm, and the other end is connected to the input terminal of the primary winding of the corresponding phase of the three-phase integrated magnetic component. The controller is used to send pulse frequency modulation drive signals to the primary-side switching network and control the drive signals of phase A, phase B and phase C bridge arms to be 120 degrees out of phase.

4. A three-phase LLC charging module based on magnetic integration according to claim 1, characterized in that, The three-phase integrated magnetic component includes a closed magnetic core assembly and a winding assembly; The closed magnetic core assembly adopts a three-column structure, including a first magnetic column, a second magnetic column and a third magnetic column arranged in parallel, and an upper magnetic yoke and a lower magnetic yoke that are laterally connected across the two ends of the first magnetic column, the second magnetic column and the third magnetic column; The winding assembly includes three sets of windings: the primary winding of phase A and the secondary winding of phase A are coaxially wound on the first magnetic post; the primary winding of phase B and the secondary winding of phase B are coaxially wound on the second magnetic post; and the primary winding of phase C and the secondary winding of phase C are coaxially wound on the third magnetic post.

5. A three-phase LLC charging module based on magnetic integration according to claim 4, characterized in that, The structural features for achieving magnetic integration in the three-phase integrated magnetic component also include: When an excitation current with a phase difference of 120 degrees is applied to the three-phase primary winding, the magnetic flux generated by the first, second, and third magnetic pillars is vector-superimposed at the upper and lower magnetic yokes, so that the algebraic sum of the AC magnetic flux in the common magnetic circuit approaches zero, thereby achieving magnetic flux cancellation and decoupling.

6. A three-phase LLC charging module based on magnetic integration according to claim 1, characterized in that, The input EMI filter circuit includes: The two-stage common-mode filter unit consists of a first-stage common-mode inductor and a second-stage common-mode inductor connected in series, along with a matching X capacitor bank and a Y capacitor bank. A soft-start unit, connected to the output side of the two-stage common-mode filter unit, includes a current-limiting resistor and a bypass relay connected in parallel with the current-limiting resistor. The bypass relay is configured to close after the DC bus voltage is established to short-circuit the current-limiting resistor.

7. A three-phase LLC charging module based on magnetic integration according to claim 1, characterized in that, The output reverse connection protection circuit includes a relay assembly or a power semiconductor switch assembly connected in series with the DC output positive bus. The charging module also includes an output sampling feedback unit for collecting the polarity of the output voltage; The controller is used to execute the following reverse connection protection logic: before the relay assembly is closed, the polarity of the output voltage is detected. If the voltage polarity is detected to be negative, the relay assembly is locked in the open state. The relay assembly is allowed to close only when the voltage polarity is detected to be correct or there is no voltage.

8. A three-phase LLC charging module based on magnetic integration according to claim 1, characterized in that, The secondary rectifier network is connected to the secondary winding of the three-phase integrated magnet; The secondary rectifier network adopts a full-wave rectifier structure or a center-tapped rectifier structure to rectify the three-phase high-frequency AC power into pulsating DC power. The pulsating DC current converges at the DC bus, and an output filter capacitor bank is connected in parallel on the DC bus to filter out high-frequency ripple.

9. A three-phase LLC charging module based on magnetic integration according to claim 1, characterized in that, The controller adjusts the output voltage or output current in the following way: The controller performs pulse frequency modulation control based on the voltage gain model of a three-phase LLC converter. The voltage gain model is a function of the normalized switching frequency, inductance ratio, and quality factor, where the normalized switching frequency is the ratio of the actual switching frequency to the resonant frequency, the inductance ratio is the ratio of the magnetizing inductance of the three-phase integrated magnet to the leakage inductance, and the quality factor is related to the load impedance. The controller collects the actual output voltage and output current, compares them with the target reference, and uses the negative gain slope characteristics of the voltage gain model in the inductive operating region to adjust the switching frequency and stabilize the output.

10. A three-phase LLC charging module based on magnetic integration according to claim 3, characterized in that, The controller is also used to execute soft-start control strategies: At startup, the controller controls the primary-side switching network to operate at a preset maximum switching frequency; Subsequently, the controller controls the switching frequency to decrease from the highest switching frequency to the operating frequency point at a preset slope until the output voltage reaches the closed-loop stable point.

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