An OBC-LDC integrated three-port LLC resonant converter and a control method thereof

Abstract

The application discloses an OBC-LDC integrated three-port LLC resonant converter and a control method thereof, relates to the technical field of electric vehicle charging, and solves the problems of a narrow high-voltage port output voltage range and poor low-voltage port stability of an existing integrated on-board charger; the converter comprises an input port full-bridge network, an LLC resonant network, a multi-winding transformer, a high-voltage port full-bridge network, a low-voltage port rectifying unit and a step-down network, and the corresponding control method comprises a charger mode, a low-voltage direct-current converter mode and a simultaneous charging mode; in the charger mode, a hybrid frequency conversion-phase shift control is adopted to cooperatively adjust a switching frequency and a phase shift angle, so that the high-voltage output range is widened; in the low-voltage direct-current converter mode, a feedforward voltage control is adopted to suppress the disturbance of high-voltage port wide voltage fluctuation on the low-voltage port; the application widens the high-voltage port output voltage range and guarantees the voltage stabilization precision of the low-voltage port while ensuring the soft switching characteristic.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle charging technology, specifically to an OBC-LDC integrated three-port LLC resonant converter and its control method. Background Technology

[0002] The electrical system of an electric vehicle comprises three parts: power supply, drive, and auxiliary subsystems. The power supply subsystem includes an on-board charger, a high-voltage battery, and a battery management system; the drive subsystem includes an electric motor and a motor controller; and the auxiliary subsystem includes a low-voltage auxiliary battery, a low-voltage DC-DC converter, and on-board electronic equipment. The on-board charger converts AC power from the grid into DC power to charge the high-voltage battery; the low-voltage DC-DC converter converts the high voltage of the high-voltage battery into low voltage to power low-voltage electrical equipment and charge the low-voltage battery. In traditional power supply methods, the circuits of the on-board charger and the low-voltage DC-DC converter operate separately, resulting in drawbacks such as large space requirements, high cost, and low efficiency.

[0003] To optimize traditional on-board power conversion equipment, integrated three-port LLC resonant converters combine the functions of on-board converter (OBC) and low-voltage converter (LDC) into a single magnetic device. Due to their advantages of high power density, good soft-switching characteristics, and high conversion efficiency, they have attracted widespread attention in electric vehicle charging systems. However, the control strategy of traditional three-port LLC resonant converters is limited by the resonant cavity gain characteristics, resulting in a limited adjustable range of the high-voltage port output voltage, making it difficult to meet the wide-voltage charging requirements of high-voltage power batteries. Simultaneously, the wide voltage range variation at the high-voltage port leads to large input disturbances and poor stability at the low-voltage port of the three-port LLC resonant converter. Existing converters struggle to simultaneously achieve a wide output voltage adjustment range and high steady-state accuracy across multiple ports. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides an OBC-LDC integrated three-port LLC resonant converter and its control method, which solves the problems of narrow output voltage range of the high-voltage port and poor stability of the low-voltage port in existing integrated on-board chargers.

[0005] An OBC-LDC integrated three-port LLC resonant converter includes:

[0006] Input port full-bridge network, LLC resonant network, multi-winding transformer, high-voltage port full-bridge network, low-voltage port center-tapped rectifier network, and low-voltage side Buck voltage regulator network;

[0007] The input port full-bridge network is connected to the primary winding of the multi-winding transformer through an LLC resonant network;

[0008] The high-voltage secondary winding of the multi-winding transformer is connected to the high-voltage port full-bridge network;

[0009] The low-voltage secondary center-tapped winding of the multi-winding transformer is connected to the input terminal of the low-voltage port center-tapped rectifier network, and the output terminal of the low-voltage port center-tapped rectifier network is connected to the low-voltage side Buck voltage regulator network.

[0010] Furthermore, the input port full-bridge network is composed of MOSFETs S1, S2, S3, and S4, their respective parallel diodes D1 to D4, and junction capacitors C1 to C4, and includes an input DC bus filter capacitor C. in and input ports;

[0011] The LLC resonant network consists of a resonant inductor L r Resonant capacitor C r And excitation inductance L m constitute;

[0012] The high-voltage port full-bridge network consists of MOSFETs S5, S6, S7, and S8, their respective parallel diodes D5 to D8, and junction capacitors C5 to C8, and includes a high-voltage port bus filter capacitor C. o1 and high-voltage ports;

[0013] The low-voltage port center-tap rectifier network consists of rectifier diodes D. a and rectifier diode D b constitute;

[0014] The low-voltage side Buck voltage regulator network consists of a buck switching transistor S. buck Freewheeling diode D buck Output filter inductor L b and low-voltage port bus filter capacitor C o2 It is configured and equipped with a low-voltage port;

[0015] The internal connection of the input port full-bridge network consists of MOSFETs S1 and S2 connected in series to form the left bridge arm, and MOSFETs S3 and S4 connected in series to form the right bridge arm. The two bridge arms are connected in parallel and then connected across the input DC bus filter capacitor C. in The midpoint between S1 and S2 leads to terminal A, and the midpoint between S3 and S4 leads to terminal B. Terminals A and B are the output nodes of the full-bridge circuit. The output nodes are connected via a resonant inductor L. r Resonant capacitor C r The magnetizing inductance L is then connected to both ends of the primary winding of the transformer. m Connected in parallel to both ends of the primary winding of the transformer;

[0016] The high-voltage port full-bridge network is internally connected by MOSFETs S5 and S6 in series to form the left bridge arm, and MOSFETs S7 and S8 in series to form the right bridge arm. The two bridge arms are connected in parallel and then connected across the high-voltage port bus filter capacitor C. o1Both ends; the midpoints of S5 and S6 and the midpoints of S7 and S8 are respectively connected to the two ends of the high-voltage secondary winding of the transformer;

[0017] Rectifier diode D a The anode and rectifier diode D b The anodes of the diodes serve as the input terminals of the low-voltage port center-tapped rectifier network, connected to both ends of the center-tapped winding of the low-voltage secondary side of the multi-winding transformer; rectifier diode D... a Cathode and rectifier diode D b The cathodes are interconnected, and the common node between them serves as the positive output terminal of the low-voltage port center tap rectifier network.

[0018] The internal connection of the low-voltage side Buck voltage regulator network is made by the step-down switching transistor S. buck One end is connected to diode D a Cathode and rectifier diode D b The common node of the cathode is the positive output terminal of the low-voltage port center-tapped rectifier network, and the other end is connected to the output filter inductor L. b Connect to the positive terminal of the low-voltage port; freewheeling diode D buck Anode grounded, cathode connected to L b With S buck Connection nodes; Low-voltage port bus filter capacitor C o2 Connected in parallel across the low-voltage port.

[0019] A control method for an OBC-LDC integrated three-port LLC resonant converter includes: charger mode, low-voltage DC-DC converter mode, and simultaneous charging mode;

[0020] In charger mode, a hybrid frequency conversion-phase shift control is used to coordinate the adjustment of the switching frequency and phase shift angle, thereby widening the high voltage output range;

[0021] In low-voltage DC-DC converter mode, feedforward voltage control is used to suppress the disturbance of wide voltage fluctuations at the high-voltage port to the low-voltage port.

[0022] In simultaneous charging mode, a strategy combining primary-side hybrid frequency-shift and low-voltage port independent PWM control is adopted to achieve multi-port power decoupling and independent precise voltage regulation.

[0023] Furthermore, depending on the actual application scenario, the mode selection is determined by the vehicle energy management system based on the charging demand status of the high-voltage power battery and the low-voltage storage battery:

[0024] The charger mode is suitable for scenarios where only high-voltage power batteries need to be charged; energy flows from the input port to the high-voltage port; a wide range of high-voltage output is achieved by adjusting the phase shift angle or operating frequency of the full-bridge network at the input port, and the high-voltage full-bridge operates as a rectifier bridge;

[0025] The low-voltage DC-DC converter mode is suitable for scenarios where the high-voltage power battery energy only needs to be converted into low-voltage power to supply the vehicle's electrical system when the vehicle is in motion or the external AC power is disconnected. Energy flows from the high-voltage port to the low-voltage port. Low-voltage regulation is achieved by adjusting the duty cycle of the two pairs of MOSFETs in the full-bridge network of the high-voltage port in conjunction with feedforward voltage control. The low-voltage side rectifier network works as a rectifier bridge.

[0026] Simultaneous charging mode is suitable for scenarios that require simultaneous charging of high-voltage power batteries and power supply to low-voltage electrical equipment; energy flows from the input port to the high-voltage port and the low-voltage port; the operating frequency and phase shift angle of the full-bridge network at the input port are adjusted to control the output voltage of the high-voltage port; the duty cycle of the buck MOSFET in the low-voltage side Buck regulator network is independently adjusted to control the output voltage of the low-voltage port.

[0027] Furthermore, in the charger mode:

[0028] The input port serves as a DC input terminal, and the high-voltage port outputs DC power with a wide voltage range to charge the high-voltage power battery of the electric vehicle. At this time, the low-voltage side Buck voltage regulator network is disconnected, the low-voltage winding is equivalent to an open circuit, and the low-voltage port is in a non-working state.

[0029] During the control process, a hybrid frequency-phase shift control strategy is adopted. By coordinating the adjustment of the operating frequency and phase shift angle of the input port full-bridge network, the output voltage of the high-voltage port is precisely controlled. The high-voltage port full-bridge network is used as a rectifier bridge.

[0030] Furthermore, the hybrid frequency-phase-shift control strategy includes dividing the operating range into two modes based on the required voltage gain: when the required gain M < 1, it is a phase-shift buck mode, which sets the operating frequency f of the switching transistor... s The resonant frequency f of the resonant network is fixed. r The output voltage is reduced by adjusting the phase shift angle α between the diagonal MOSFETs in the full-bridge network at the input port. When the required gain M ≥ 1, it is in frequency conversion boost mode, where the phase shift angle α is set to 0, and the operating frequency f is reduced. s To increase voltage gain.

[0031] Furthermore, in the low-voltage DC-DC converter mode:

[0032] The high-voltage power battery at the high-voltage port provides DC input, and the low-voltage port outputs low-voltage DC power to power the low-voltage battery and low-voltage electrical equipment. At this time, the entire bridge network of the input port is disconnected.

[0033] During the control process, the buck switch in the low-voltage side Buck voltage regulator network remains constantly on. A feedforward voltage control strategy is adopted, which combines feedforward compensation of the high-voltage port input voltage with feedback adjustment of the actual output voltage of the low-voltage port to adjust the duty cycle of the high-voltage port full-bridge network, thereby achieving stable control of the low-voltage port output voltage.

[0034] Furthermore, in the simultaneous charging mode:

[0035] The input port receives DC power, the high-voltage port outputs high-voltage DC power, and the low-voltage port outputs low-voltage DC power.

[0036] At this time, a hybrid frequency-phase shift control strategy is adopted for the high-voltage port to adjust the operating frequency and phase shift angle of the full-bridge network at the input port in order to control the output voltage of the high-voltage port.

[0037] A PWM control strategy is adopted for the low-voltage port. By independently adjusting the duty cycle of the MOSFET in the Buck regulator network on the low-voltage side, the output voltage of the low-voltage port is controlled, thereby achieving independent and precise voltage regulation of the two ports.

[0038] Furthermore, the coordinated design of the charging mode at the control level is as follows:

[0039] Regarding timing coordination, the low-voltage side Buck switch S buck The turn-on timing of the transistor and the primary-side MOSFET have a strict phase match, and the phase match includes S... buck It is turned on during the primary side conduction period and turned off synchronously with the primary side during the primary side dead time to avoid the dead time voltage drop causing disturbance to the low voltage port.

[0040] In terms of power decoupling, the power flow at the high-voltage port is independently determined by the input port frequency-phase shift control, while the power flow at the low-voltage port is independently determined by the Buck-side PWM. The two control loops do not interfere with each other.

[0041] Regarding disturbance suppression, through the aforementioned timing coordination, even if the load on the high-voltage side undergoes a sudden change, the output voltage of the low-voltage port will not be affected by coupling.

[0042] The beneficial effects of this invention include:

[0043] Compared to existing three-port converters, the novel integrated OBC-LDC three-port converter of this invention addresses the problem of large frequency variations in traditional single-frequency control under wide gain requirements. In charger mode, this invention employs a hybrid frequency-phase-shift control method. While ensuring zero-voltage conduction of the primary-side power switch, it effectively widens the output voltage regulation range of the high-voltage port by coordinating frequency and phase shift angle, avoiding additional losses caused by excessively high switching frequencies.

[0044] To address the issue of wide input disturbances at the low-voltage port caused by the wide voltage range at the high-voltage port in low-voltage DC-DC converter mode, this invention proposes a feedforward voltage control method. By combining input voltage feedforward compensation and output voltage feedback regulation, the voltage regulation accuracy and dynamic anti-interference performance of the low-voltage port are significantly improved under wide voltage fluctuations of the high-voltage power battery.

[0045] In simultaneous charging mode, by cleverly combining primary-side frequency-phase shift control with PWM control of the low-voltage port Buck circuit, the system can achieve power decoupling of high-voltage battery charging and low-voltage equipment power supply within the same high-frequency switching cycle, realizing independent and precise voltage regulation of the dual ports. Attached Figure Description

[0046] Figure 1 This is a system circuit diagram according to an embodiment of the present invention;

[0047] Figure 2 The following are structural block diagrams of the controllers for three working modes in the embodiments of the present invention: (a) is a structural diagram of the hybrid frequency-phase shift closed-loop controller in charger mode; (b) is a structural diagram of the feedforward voltage closed-loop controller in low-voltage DC-DC converter mode; and (c) is a structural diagram of the closed-loop controller in simultaneous charging mode.

[0048] Figure 3 The following are control timing diagrams for three operating modes in embodiments of the present invention: (a) is the phase-shifting timing diagram in charger mode, (b) is the frequency conversion timing diagram in charger mode, (c) is the timing diagram of the low-voltage DC converter, and (d) is the timing diagram in simultaneous charging mode.

[0049] Figure 4 This is a modal diagram of phase-shift control in charger mode according to an embodiment of the present invention, wherein (a) is the phase-shift mode. The modes within the time interval, (b) is the phase-shifting mode. The modes within the time interval, (c) represents the phase-shifting mode. The modes within the time interval, (d) represents the phase-shifting mode. The modes within the time interval, (e) represents the phase-shifting mode. Modalities within a time period;

[0050] Figure 5 This is a modal diagram of frequency conversion control in charger mode according to an embodiment of the present invention, wherein (a) is the frequency conversion mode. The modes within the time interval, (b) is the mode under frequency conversion mode. The modes within the time interval, (c) represents the frequency conversion mode. Modalities within a time period;

[0051] Figure 6This is a mode diagram of an embodiment of the present invention in low-voltage DC-DC converter mode, wherein (a) is The mode within time, (b) is Modalities within a time period;

[0052] Figure 7 This is a modal diagram of the present invention in simultaneous charging mode, wherein (a) is The mode within time, (b) is The mode within time, (c) is Modalities within a time period;

[0053] Figure 8 The above describes the simulation waveforms in charger mode according to an embodiment of the present invention. Figure 1 Wherein, (a) is the steady-state waveform under phase-shift control, and (b) is the steady-state waveform under frequency conversion control.

[0054] Figure 9 The above describes the simulation waveforms in charger mode according to an embodiment of the present invention. Figure 2 (a) is the transient waveform of the high-voltage port output voltage step from 250 to 400V, and (b) is the transient waveform of the high-voltage port output voltage step from 400 to 600V.

[0055] Figure 10 This is a simulation waveform diagram of an embodiment of the present invention in low-voltage DC-DC converter mode;

[0056] Figure 11 The following are simulation waveforms of load current sudden change in an embodiment of the present invention, wherein (a) is a simulation waveform of high voltage port current sudden change in simultaneous charging mode in an embodiment of the present invention, and (b) is a simulation waveform of low voltage port current sudden change in simultaneous charging mode. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0058] Example 1

[0059] The following is in conjunction with the appendix Figure 1 Specific embodiments of the present invention will be described in detail;

[0060] An OBC-LDC integrated three-port LLC resonant converter includes: an input port full-bridge network, an LLC resonant network, a multi-winding transformer, a high-voltage port full-bridge network, a low-voltage port center-tapped rectifier network, and a low-voltage side Buck voltage regulator network.

[0061] The input port full-bridge network is connected to the primary winding of the multi-winding transformer via the LLC resonant network; the high-voltage secondary winding of the multi-winding transformer is connected to the high-voltage port full-bridge network; the low-voltage secondary center-tapped winding of the multi-winding transformer is connected to the low-voltage port center-tapped rectifier network, and the output of the low-voltage port center-tapped rectifier network is connected to the low-voltage side Buck voltage regulator network. The specific circuit structure is as follows: Figure 1 As shown:

[0062] The input port full-bridge network consists of the input DC bus filter capacitor C. in It consists of MOSFETs S1, S2, S3, and S4, their respective parallel diodes D1 to D4, and junction capacitances C1 to C4;

[0063] The LLC resonant network consists of a resonant inductor L r Resonant capacitor C r And excitation inductance L m constitute;

[0064] The high-voltage port full-bridge network consists of MOSFETs S5, S6, S7, and S8, their respective parallel diodes D5 to D8, junction capacitors C5 to C8, and the high-voltage port bus filter capacitor C. o1 The high-voltage port full-bridge network also includes high-voltage ports. ;

[0065] The low-voltage port center-tap rectifier network consists of rectifier diode D a and rectifier diode D b constitute;

[0066] The low-voltage side Buck regulator network consists of a step-down MOSFET S buck Freewheeling diode D buck Output filter inductor L b and low-voltage port bus filter capacitor C o2 The low-voltage side Buck voltage regulator network also includes a low-voltage port. .

[0067] The internal connection of the input port full-bridge network consists of MOSFETs S1 and S2 connected in series to form the left bridge arm, and MOSFETs S3 and S4 connected in series to form the right bridge arm. The two bridge arms are connected in parallel and then connected across the input DC bus filter capacitor C. inThe midpoint between S1 and S2 leads to terminal A, and the midpoint between S3 and S4 leads to terminal B. Terminals A and B are the output nodes of the full-bridge circuit. The output nodes are connected via a resonant inductor L. r Resonant capacitor C r The magnetizing inductance L is then connected to both ends of the primary winding of the transformer. m Connected in parallel to both ends of the primary winding of the transformer;

[0068] The high-voltage port full-bridge network is internally connected by MOSFETs S5 and S6 in series to form the left bridge arm, and MOSFETs S7 and S8 in series to form the right bridge arm. The two bridge arms are connected in parallel and then connected across the high-voltage port bus filter capacitor C. o1 Both ends; the midpoints of S5 and S6 and the midpoints of S7 and S8 are respectively connected to the two ends of the high-voltage secondary winding of the transformer;

[0069] Rectifier diode D a The anode and rectifier diode D b The anodes of the diodes serve as the input terminals of the low-voltage port center-tapped rectifier network, connected to both ends of the center-tapped winding of the low-voltage secondary side of the multi-winding transformer; rectifier diode D... a Cathode and rectifier diode D b The cathodes are interconnected, and the common node between them serves as the positive output terminal of the low-voltage port center tap rectifier network.

[0070] The internal connection of the low-voltage side Buck voltage regulator network is made by the step-down switching transistor S. buck One end is connected to diode D a Cathode and rectifier diode D b The common node of the cathode (i.e., the positive output terminal of the low-voltage port center-tapped rectifier network), and the other end is connected to the output filter inductor L. b Connect to the positive terminal of the low-voltage port; freewheeling diode D buck Anode grounded, cathode connected to L b With S buck Connection nodes; Low-voltage port bus filter capacitor C o2 Connected in parallel across the low-voltage port.

[0071] In this embodiment, within each full-bridge network, diagonally opposite MOSFETs form a pair. The same pair of MOSFETs receives the same control signal, while the control signals between the two pairs of MOSFETs have the same duty cycle or frequency and are 180 degrees out of phase. Furthermore, the buck MOSFET S in the low-voltage side Buck regulator network... buck It receives independent PWM control signals to achieve buck regulation control of the low-voltage port.

[0072] In another embodiment, a control method for a wide-range integrated OBC-LDC three-port LLC resonant converter system is provided for controlling an OBC-LDC integrated three-port LLC resonant converter. The charging modes controlled by the control method include: charger mode, low-voltage DC converter mode, and simultaneous charging mode.

[0073] In charger mode, a hybrid frequency conversion-phase shift control strategy is adopted to coordinate the adjustment of switching frequency and phase shift angle, thereby widening the high voltage output range;

[0074] In low-voltage DC-DC converter mode, a feedforward voltage control strategy is adopted to suppress the disturbance of wide voltage fluctuations at the high-voltage port to the low-voltage port.

[0075] In simultaneous charging mode, a strategy combining primary-side hybrid frequency-shift and low-voltage port independent PWM control is adopted to achieve multi-port power decoupling and independent precise voltage regulation.

[0076] Depending on the actual application scenario, the mode selection is determined by the vehicle energy management system (BMS) based on the charging demand status of the high-voltage power battery and the low-voltage storage battery:

[0077] The charger mode is suitable for scenarios where only high-voltage power batteries need to be charged. Energy flows from the input port to the high-voltage port. A wide range of high-voltage output is achieved by adjusting the phase shift angle or operating frequency of the full-bridge network at the input port, with the high-voltage full-bridge acting as a rectifier bridge.

[0078] The low-voltage DC-DC converter mode is suitable for scenarios where the vehicle is in motion or the external AC power is disconnected, and only the energy from the high-voltage power battery needs to be converted into low voltage for use by the vehicle's electrical system. Energy flows from the high-voltage port to the low-voltage port. Low-voltage regulation is achieved by adjusting the duty cycle of the two pairs of MOSFETs in the full-bridge network at the high-voltage port in conjunction with feedforward voltage control, while the low-voltage side rectifier network operates as a rectifier bridge.

[0079] Simultaneous charging mode is suitable for scenarios requiring simultaneous charging of high-voltage power batteries and power supply to low-voltage electrical equipment. Energy flows from the input port to both the high-voltage and low-voltage ports. Adjusting the operating frequency and phase shift angle of the full-bridge network at the input port controls the output voltage of the high-voltage port; independently adjusting the duty cycle of the buck MOSFET in the low-voltage side Buck regulator network controls the output voltage of the low-voltage port.

[0080] In another embodiment, in charger mode, the input port full-bridge network serves as the DC input terminal, and the high-voltage port outputs DC power with a wide voltage range to charge the high-voltage power battery of the electric vehicle. At this time, the low-voltage side Buck voltage regulator network is disconnected, and the low-voltage port is in a non-working state. During the control process, the phase or frequency of the input port full-bridge network is adjusted by a hybrid frequency conversion-phase shift control strategy to achieve precise control of the output voltage. The full-bridge portion of the high-voltage port is used as a rectifier bridge.

[0081] In this embodiment, in charger mode, the relationship between the input and output voltages depends on the voltage gain M of the LLC resonant network, satisfying V HV =(V in *M) / n, where n is the transformer turns ratio between the primary winding at the input port and the secondary winding at the high-voltage port. The operating frequency f of the full-bridge network at the input port is adjusted collaboratively. s The phase shift angle α is used to control the stability of the output voltage VHV at the high-voltage port.

[0082] To balance soft-switching characteristics over a wide voltage range and avoid excessive switching losses caused by deep bucking in a single frequency converter, the hybrid frequency converter-phase shift control strategy includes two operating ranges based on the required voltage gain: a phase-shift buck mode and a frequency converter boost mode.

[0083] When the required gain M < 1, it is in phase-shift buck mode, and the operating frequency f of the switching transistor is reduced. s The resonant frequency f of the resonant network is fixed. r The output voltage is reduced by adjusting the phase shift angle α between the diagonal MOSFETs in the full-bridge network at the input port. When the required gain M ≥ 1, it is in frequency conversion boost mode, where the phase shift angle α is set to 0, and the operating frequency f is reduced. s To improve voltage gain; because when M=1, the converter operates at the resonant frequency point, with maximum gain and optimal efficiency, thus it is included in the boundary conditions of the frequency conversion boost mode.

[0084] This strategy employs a unified logic selection closed-loop controller, such as... Figure 2 As shown in (a), the controller internally employs voltage PI control. By comparing the actual voltage with the reference target value, it logically determines the required gain range, thereby smoothly switching the converter between phase-shift buck mode and frequency-boost mode. Specifically, v HV_ref This is the target reference value output at the high-voltage port. When v HV <v HV_ref When the required gain M≥1, the logic selector activates the frequency converter PI controller, increasing the gain by reducing the operating frequency fs; when v HV ≥ v HV_ref When the required gain M < 1, the logic selector activates the phase-shift control PI controller, which reduces the output voltage by adjusting the phase-shift angle α, thereby achieving a smooth switch between the two operating ranges.

[0085] In another embodiment, in low-voltage DC-DC converter mode: the high-voltage power battery at the high-voltage port provides DC input, and the low-voltage port outputs low-voltage DC power to supply power to the low-voltage battery and on-board low-voltage electrical equipment; at this time, the entire bridge network at the input port is disconnected. During the control process, voltage control is achieved by adjusting the duty cycle of the two pairs of MOSFETs in the full-bridge section of the high-voltage port, and the center-tapped network at the low-voltage port is used as a rectifier bridge.

[0086] In this embodiment, in low-voltage DC-DC converter mode, the high-voltage port transfers energy to the low-voltage port via a transformer. The buck switch S in the low-voltage side Buck voltage regulator network... buck Maintaining constant conduction, the output voltage is controlled by adjusting the duty cycle D of MOSFETs S5, S6, S7, and S8 in the high-voltage port full-bridge network, where the duty cycle D is less than 0.5. The output voltage at the low-voltage port is proportional to the input voltage at the high-voltage port, and its proportionality coefficient is related to the turns ratio of the high-voltage secondary winding and the low-voltage secondary winding. To eliminate the wide input disturbance caused by wide voltage fluctuations of the high-voltage power battery on the low-voltage output, this embodiment employs a feedforward voltage control strategy. Figure 2 As shown in (b), the closed-loop control process will control the actual output voltage v at the low-voltage port. LV With reference target signal v LV_ref The comparison is performed, and the error signal is input to the PI controller; simultaneously, the system introduces the actual output voltage v from the high-voltage port. HV The output voltage of the PI controller is compensated by multiplying the input voltage by the corresponding feedforward coefficient as a feedforward term. The compensated combined signal is then processed by gain and limiter to finally generate the duty cycle modulation signal of the high-voltage port full-bridge network switching transistors. By combining input voltage feedforward compensation and output voltage feedback regulation, the voltage regulation accuracy and dynamic response performance of the low-voltage port are effectively guaranteed over a wide range of high voltage variations.

[0087] In another embodiment, under simultaneous charging mode: DC power is input at the input port, high-voltage DC power is output at the high-voltage port, and low-voltage DC power is output at the low-voltage port; the strategy of independent PWM control of the low-voltage port by combining primary-side hybrid frequency-shift includes adjusting the operating frequency and phase shift angle of the full-bridge network at the input port to control the output voltage of the high-voltage port; and independently adjusting the duty cycle of the buck MOSFET in the low-voltage side Buck regulator network to control the output voltage of the low-voltage port.

[0088] In this embodiment, in simultaneous charging mode, the control method of the input port is the same as that of the charger mode, that is, by coordinating the switching frequency of MOSFETs S1, S2, S3, and S4 in the full-bridge network of the input port and the phase shift angle between the diagonal bridge arms, the stability of the high-voltage port output voltage is controlled. For the low-voltage port, an independent PWM control strategy is adopted, by adjusting the step-down switch S in the low-voltage side Buck regulator network. buckVoltage regulation is achieved by adjusting the duty cycle. For example... Figure 2 As shown in (c), the closed-loop control circuit uses a voltage PI controller. Specifically, v LV_ref The target reference value is output from the low-voltage port. The actual output voltage V at the low-voltage port is sampled. LV With v LV_ref The difference is used to obtain the error signal, which is then processed by the low-voltage port PI controller to output the duty cycle adjustment. To prevent the duty cycle from exceeding the safe operating range of the device, the PI output is constrained to a reasonable range by a limiting circuit. The result after limiting is used as the step-down switching transistor S. buck The target duty cycle is modulated to generate S. buck Drive pulse, by real-time adjustment of S buck The conduction time stabilizes the low-voltage port output voltage at V. LV_ref This collaborative control strategy enables the system to simultaneously meet the requirements of wide-voltage charging of the high-voltage power battery and stable power supply of the low-voltage port within the same high-frequency switching cycle, effectively eliminating multi-port power coupling disturbances under a wide range of operating conditions.

[0089] Meanwhile, the coordinated design of the charging mode at the control level is as follows:

[0090] Timing Coordination: The turn-on timing of the low-side Buck switch Sbuck and the primary-side MOSFET ( The conduction timing of the Sbuck exhibits strict phase coordination—the Sbuck is turned on during the primary-side conduction period. ), and shut down synchronously with the original edge during the original edge dead zone time. This avoids dead-zone voltage drops causing disturbances to the low-voltage port.

[0091] Power decoupling: The power flow at the high-voltage port is independently determined by the input port frequency-phase shift control, while the power flow at the low-voltage port is independently determined by the Buck-side PWM. The two control loops do not interfere with each other, thus achieving dual-port power decoupling within the same magnetic device.

[0092] Disturbance suppression: Through the above timing coordination, even if the load on the high-voltage side changes abruptly, the output voltage of the low-voltage port will not be affected by coupling.

[0093] Figure 3 The timing diagrams for the integrated OBC-LDC three-port LLC resonant converter in three modes are shown below. Figure 3 (a) in the diagram is the phase shift control timing diagram in charger mode. Figure 3 (b) in the diagram is the frequency converter control timing diagram in charger mode. Figure 3 (c) in the diagram is the timing diagram for the low-voltage DC-DC converter mode. Figure 3 (d) in the diagram is the timing diagram for simultaneous charging mode.

[0094] When phase-shift control is used in charger mode, it includes Figure 4 The five modes are (a), (b), (c), (d), and (e). Within a time ( Figure 4 In (a) the MOSFET S2 is turned off, and at this time the primary resonant inductor L r current i Lr The junction capacitance of MOSFET S2 is charged, while the junction capacitance of MOSFET S1 is discharged. Since this phase lasts for an extremely short time, the resonant inductor current i... Lr and excitation current i Lm The load at the high-voltage port remains approximately constant, and the load is supplied by the high-voltage port bus filter capacitor C. o1 Power supply. In Within a time ( Figure 4 In (b), the junction capacitance voltage of MOSFET S1 discharges to zero, its body diode conducts, and subsequently, when a drive signal is applied to MOSFET S1, it achieves zero-voltage turn-on. At this time, the input voltage v in The resonant inductor current i is applied across the resonant network. Lr and transformer excitation current i Lm The voltage initially rises linearly, and the body diodes of MOSFETs S5 and S8 conduct to rectify the current, clamping the secondary voltage to the high-voltage port voltage V. HV .exist Within a time ( Figure 4 In the middle (c), MOSFET S1 is turned off, and the resonant inductor current i Lr The junction capacitance of MOSFET S1 is charged, while the junction capacitance of MOSFET S3 is discharged. During this period, the body diodes of MOSFETs S5 and S8 remain conducting, the primary voltage of the transformer is maintained, and the magnetizing current i... Lm It continues to rise linearly. Within a time ( Figure 4 In step (d), the junction capacitance voltage of MOSFET S3 drops to zero, its body diode conducts, and MOSFET S3 subsequently achieves zero-voltage turn-on. The high-voltage port continues rectification, and the resonant cavity withstands the reverse clamping voltage. Within a time ( Figure 4 In the middle (e), the resonant inductor current i Lr With excitation current i Lm When the current is equal to zero, the primary current of the transformer decreases to zero, and the body diode current of the rectifier at the high-voltage port also decreases to zero accordingly, achieving zero-current turn-off and avoiding reverse recovery losses. Afterwards, the resonant inductor L... r Transformer magnetizing inductance L m With resonant capacitor C r They all participate in the resonance, and the load is the high-voltage port bus filter capacitor C. o1 Power supply. In the second half of the cycle, its working principle is reverse-symmetrical to that of the first half of the cycle.

[0095] When using frequency conversion control in charger mode, including Figure 5 The three modes (a), (b), and (c) are mentioned. Within a time ( Figure 5 In (a), all MOSFETs S1 to S4 are turned off. The resonant inductor current i Lr The junction capacitances of MOSFETs S2 and S3 are charged, while the junction capacitances of MOSFETs S1 and S4 are discharged. During this stage, the high-voltage side load is still powered by the bus filter capacitor Co1. Within a time ( Figure 5 In (b), the junction capacitance voltage of MOSFETs S1 and S4 drops to 0, their body diodes conduct, and subsequently MOSFETs S1 and S4 achieve zero-voltage turn-on. At this time, the input voltage v in The resonant inductor current i applied to the resonant cavity Lr With rapid increase, the body diodes of MOSFETs S5 and S8 conduct, clamping the secondary voltage to the high-voltage port voltage V. HV Excitation current i Lm Linear increase. Within a time ( Figure 5 (c)), resonant inductor current i Lr With excitation current i Lm When the currents are equal, the primary current of the transformer decreases to 0, and the currents of the body diodes of MOSFETs S5 and S8 also decrease to 0, achieving zero-current turn-off. During this period, L r L m C r They participate in resonance together, because L m Larger, i Lr It remains approximately constant. At time t3, MOSFETs S1 and S4 are turned off, entering the second half of the switching cycle, which is inversely symmetrical to the principle of the first half of the cycle.

[0096] In low-voltage DC-DC converter mode, including Figure 6 The two modes (a) and (b) in the text. Within a time ( Figure 6 In (a), MOSFETs S5 and S8 are turned on, and the high-voltage port voltage V HV It is applied to the high-voltage winding of the transformer secondary side. At the low-voltage port, diode D... b MOSFET S with low-voltage Buck regulator network buck Turn-on. A forward rectified voltage is applied to the input of the Buck network, causing the low-voltage port filter inductor L to conduct. b When in an energy storage state, the inductor current i Lb Linear increase. In Within a time ( Figure 6In (b), MOSFETs S5 and S8 are turned off, and MOSFET S... buck Maintain constant conduction. At this time, the low-voltage port full-wave rectifier enters freewheeling mode, and diode D... a With D b Simultaneously, the circuit is turned on, the induced voltage is 0, and the low-voltage port filter inductor L... b Freewheeling discharge, inductor current i Lb Linear decrease.

[0097] In simultaneous charging mode, including Figure 7 The three modes (a), (b), and (c) are mentioned. Within a time ( Figure 7 In (a) of the circuit, MOSFETs S1 and S4 are turned on, and energy is transferred from the input port to the high-voltage port. At this time, MOSFET S1 and S4 are turned on. buck When in the off state, the low-voltage port load energy is entirely supplied by the filter inductor L. b Provided, diode D buck When the circuit is turned on, the inductor current i Lb Decline. In Within a time ( Figure 7 In (b), MOSFETs S1 and S4 remain on, and MOSFET S... buck The transformer is now activated, simultaneously transferring energy to both the high-voltage and low-voltage ports. The rectified high-level voltage is applied directly to the input of the Buck network, and diode D... buck It is cut off when subjected to reverse voltage. During this period, the filter inductor L b When in a charging and energy storage state, the inductor current i Lb Linear increase. In Within a time ( Figure 7 In step (c), MOSFETs S1 and S4 are turned off, and the system enters the dead time. Simultaneously, to prevent the dead time voltage drop from causing disturbance to the low-voltage port, the control strategy forces MOSFET S1 to turn off. buck The primary side is turned off synchronously. Filter inductor L b Force diode D again buck When the circuit is turned on, the low-voltage port resumes its independent freewheeling state, and the inductor current i Lb decline.

[0098] To verify the effectiveness of the method proposed in this embodiment, time-domain simulation analysis of the method of the present invention was performed using PSIM simulation software, and the results are as follows:

[0099] The parameters of the simulation circuit are the resonant inductance L. r =20uH, resonant capacitor C r =130nH, magnetizing inductance L m =100uH, capacitor C o1 =220uF, C o2=220uF, transformer ratio is n p :n s :n LV =20:20:1, the input voltage reference value of the input port is 400V, the output voltage reference value of the high voltage port is 400V, and the output voltage range is... The low-voltage port output voltage reference value is 12V. In charger mode, the rated output power of the high-voltage port is 3.3kW; in low-voltage DC-DC converter mode, the rated output power of the low-voltage port is 300W; in combined operation mode, the rated output power of the high-voltage port is 3kW, and the rated output power of the low-voltage port is 300W. The system resonant frequency f r It is 100kHz.

[0100] Figures 8-9 The simulation waveforms in charger mode are shown, among which, Figure 8 (a): Input V in =400V, output V HV =250V, the controller uses phase-shifting buck mode, the high voltage port maintains a constant 250V, and the high voltage port output current is 13.2A; Figure 8 (b): Input V in =400V, output V2=600V, the controller works in frequency conversion boost mode, the high voltage port maintains a constant 600V, and the high voltage port output current is 5.5A. Figure 9 (a): Transient waveform of the high-voltage port output voltage step transition from 250-400V. When the output voltage reference signal V... HV_ref When the voltage suddenly changes from 250V to 400V, the actual output voltage V HV It can respond quickly and smoothly track the reference value with minimal overshoot. Figure 9 (b): The transient waveform of the high-voltage port output voltage step of 400-600V. When the output voltage reference signal V... HV_ref When the voltage jumps further from 400V to 600V, the actual output voltage V HV It also demonstrated extremely fast dynamic response speed and excellent tracking performance.

[0101] Figure 10 This is a simulation waveform in low-voltage DC-DC converter mode, when the high-voltage port input voltage V... HV When an extreme, wide-range input disturbance occurs, jumping directly from 250V to 600V, thanks to the feedforward voltage control strategy employed in this invention, the low-voltage port output voltage V... LV A tiny transient spike appears only at the moment of switching, and it immediately recovers and remains smoothly at the expected 12V. This fully demonstrates that the control system has a strong ability to suppress wide input voltage disturbances and extremely high steady-state accuracy.

[0102] Figure 11 The following is a simulation waveform diagram of a sudden change in load current in an embodiment of the present invention: Figure 11 Figure (a) shows the simulated waveform of the sudden change in high-voltage port current under simultaneous charging mode. When the load current I at the high-voltage port... HV When a step drop occurs, the high-voltage port output voltage V HV It quickly recovers to a steady state after experiencing minor fluctuations; during this transient process, the output voltage V at the low-voltage port... LV and output current I LV The waveform was not affected by sudden changes in the high-voltage side load. Figure 11 Figure (b) shows the simulated waveform of the sudden change in low-voltage port current under simultaneous charging mode. When the low-voltage port load current I... LV When a step drop occurs, the low-voltage output voltage V LV After a brief period of slight high-frequency oscillation, it quickly returned to a stable 12V state; simultaneously, the voltage V at the high-voltage port... HV and current I HV The waveform remains smooth and constant throughout. Overall simulation results show that, under all operating modes, the wide-range integrated OBC-LDC three-port LLC resonant converter proposed in this invention exhibits excellent stability and multi-port decoupling capabilities when facing load fluctuations and large-scale voltage command abrupt changes. In charger mode, by switching control strategies, a wide-range stable output from 250V to 600V is achieved at the high-voltage port. In low-voltage DC-DC conversion mode, the 12V low-voltage output demonstrates strong anti-disturbance capability when facing drastic voltage jumps in the preceding stage. In simultaneous charging mode, perfect power decoupling is achieved between the high and low voltage ports; even if the load on one side changes drastically, it will not cause coupling effects on the other side. Compared with existing integrated converters, this invention, while broadening the high-voltage output range, robustly ensures the continuous stability of the low-voltage output, fully demonstrating its reliability under the complex power supply conditions of electric vehicles.

[0103] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. An OBC-LDC integrated three-port LLC resonant converter, characterized in that, include: Input port full-bridge network, LLC resonant network, multi-winding transformer, high-voltage port full-bridge network, low-voltage port center-tapped rectifier network, and low-voltage side Buck voltage regulator network; The input port full-bridge network is connected to the primary winding of the multi-winding transformer through an LLC resonant network; The high-voltage secondary winding of the multi-winding transformer is connected to the high-voltage port full-bridge network; The low-voltage secondary center-tapped winding of the multi-winding transformer is connected to the input terminal of the low-voltage port center-tapped rectifier network, and the output terminal of the low-voltage port center-tapped rectifier network is connected to the low-voltage side Buck voltage regulator network.

2. The OBC-LDC integrated three-port LLC resonant converter according to claim 1, characterized in that, The input port full-bridge network includes MOSFETs S1, S2, S3, and S4, along with their respective parallel diodes D1 to D4 and junction capacitors C1 to C4, and also includes an input DC bus filter capacitor. and input ports; The LLC resonant network consists of a resonant inductor L r Resonant capacitor C r And excitation inductance L m constitute; The high-voltage port full-bridge network includes MOSFETs S5, S6, S7, and S8, along with their respective parallel diodes D5 to D8 and junction capacitors C5 to C8, and is equipped with a high-voltage port bus filter capacitor C. o1 and high-voltage ports; The low-voltage port center-tap rectifier network consists of rectifier diodes D. a and rectifier diode D b constitute; The low-voltage side Buck voltage regulator network includes a buck switching transistor S. buck Freewheeling diode D buck Output filter inductor L b and low-voltage port bus filter capacitor C o2 It is equipped with a low-voltage port; The internal connection of the input port full-bridge network consists of MOSFETs S1 and S2 connected in series to form the left bridge arm, and MOSFETs S3 and S4 connected in series to form the right bridge arm. The two bridge arms are connected in parallel and then connected across the input DC bus filter capacitor C. in The midpoint between S1 and S2 leads to terminal A, and the midpoint between S3 and S4 leads to terminal B. Terminals A and B are the output nodes of the full-bridge circuit. The output nodes are connected via a resonant inductor L. r Resonant capacitor C r The magnetizing inductance L is then connected to both ends of the primary winding of the transformer. m Connected in parallel to both ends of the primary winding of the transformer; The high-voltage port full-bridge network is internally connected by MOSFETs S5 and S6 in series to form the left bridge arm, and MOSFETs S7 and S8 in series to form the right bridge arm. The two bridge arms are connected in parallel and then connected across the high-voltage port bus filter capacitor C. o1 Both ends; the midpoints of S5 and S6 and the midpoints of S7 and S8 are respectively connected to the two ends of the high-voltage secondary winding of the transformer; Rectifier diode D a The anode and rectifier diode D b The anodes of the diodes serve as the input terminals of the low-voltage port center-tapped rectifier network, connected to both ends of the center-tapped winding of the low-voltage secondary side of the multi-winding transformer; rectifier diode D... a Cathode and rectifier diode D b The cathodes are interconnected, and the common node between them serves as the positive output terminal of the low-voltage port center tap rectifier network. Step-down switching transistor S buck One end is connected to diode D a Cathode and rectifier diode D b The common node of the cathode is the positive output terminal of the low-voltage port center-tapped rectifier network, and the buck switch S... buck The other end passes through the output filter inductor L b Connect to the positive terminal of the low-voltage port; freewheeling diode D buck Anode grounded, cathode connected to L b With S buck Connection nodes; Low-voltage port bus filter capacitor C o2 Connected in parallel across the low-voltage port.

3. A control method for an OBC-LDC integrated three-port LLC resonant converter, characterized in that, For controlling an OBC-LDC integrated three-port LLC resonant converter as described in any one of claims 1-2, including: charger mode, low-voltage DC-DC converter mode and simultaneous charging mode; In charger mode, a hybrid frequency conversion-phase shift control is used to coordinate the adjustment of the switching frequency and phase shift angle, thereby widening the high voltage output range; In low-voltage DC-DC converter mode, feedforward voltage control is used to suppress the disturbance of wide voltage fluctuations at the high-voltage port to the low-voltage port. In simultaneous charging mode, a strategy combining primary-side hybrid frequency-shift and low-voltage port independent PWM control is adopted to achieve multi-port power decoupling and independent precise voltage regulation.

4. The control method for an OBC-LDC integrated three-port LLC resonant converter according to claim 3, characterized in that, Depending on the actual application scenario, the mode selection is determined by the vehicle energy management system based on the charging demand status of the high-voltage power battery and the low-voltage storage battery: The charger mode is suitable for scenarios where only high-voltage power batteries need to be charged; energy flows from the input port to the high-voltage port; a wide range of high-voltage output is achieved by adjusting the phase shift angle or operating frequency of the full-bridge network at the input port, and the high-voltage full-bridge operates as a rectifier bridge; The low-voltage DC-DC converter mode is suitable for scenarios where the high-voltage power battery energy only needs to be converted into low-voltage power to supply the vehicle's electrical system when the vehicle is in motion or the external AC power is disconnected. Energy flows from the high-voltage port to the low-voltage port. Low-voltage regulation is achieved by adjusting the duty cycle of the two pairs of MOSFETs in the full-bridge network of the high-voltage port in conjunction with feedforward voltage control. The low-voltage side rectifier network works as a rectifier bridge. Simultaneous charging mode is suitable for scenarios that require simultaneous charging of high-voltage power batteries and power supply to low-voltage electrical equipment; energy flows from the input port to the high-voltage port and the low-voltage port; the operating frequency and phase shift angle of the full-bridge network at the input port are adjusted to control the output voltage of the high-voltage port; the duty cycle of the buck MOSFET in the low-voltage side Buck regulator network is independently adjusted to control the output voltage of the low-voltage port.

5. The control method for an OBC-LDC integrated three-port LLC resonant converter according to claim 3, characterized in that, In the charger mode: The input port serves as a DC input terminal, and the high-voltage port outputs DC power with a wide voltage range to charge the high-voltage power battery of the electric vehicle. At this time, the low-voltage side Buck voltage regulator network is disconnected, the low-voltage winding is equivalent to an open circuit, and the low-voltage port is in a non-working state. During the control process, a hybrid frequency-phase shift control strategy is adopted. By coordinating the adjustment of the operating frequency and phase shift angle of the input port full-bridge network, the output voltage of the high-voltage port is precisely controlled. The high-voltage port full-bridge network is used as a rectifier bridge.

6. The control method for an OBC-LDC integrated three-port LLC resonant converter according to claim 5, characterized in that, The hybrid frequency-phase-shift control strategy includes dividing the operating range into two modes based on the required voltage gain: when the required gain M < 1, it is a phase-shift buck mode, which sets the operating frequency f of the switching transistor. s The resonant frequency f of the resonant network is fixed. r The output voltage is reduced by adjusting the phase shift angle α between the diagonal MOSFETs in the full-bridge network at the input port. When the required gain M ≥ 1, it is in frequency conversion boost mode, where the phase shift angle α is set to 0, and the operating frequency f is reduced. s To increase voltage gain.

7. The control method for an OBC-LDC integrated three-port LLC resonant converter according to claim 3, characterized in that, In the low-voltage DC-DC converter mode: The high-voltage power battery at the high-voltage port provides DC input, and the low-voltage port outputs low-voltage DC power to power the low-voltage battery and low-voltage electrical equipment. At this time, the entire bridge network of the input port is disconnected. During the control process, the buck switch in the low-voltage side Buck voltage regulator network remains constantly on. A feedforward voltage control strategy is adopted, which combines feedforward compensation of the high-voltage port input voltage with feedback adjustment of the actual output voltage of the low-voltage port to adjust the duty cycle of the high-voltage port full-bridge network, thereby achieving stable control of the low-voltage port output voltage.

8. The control method for an OBC-LDC integrated three-port LLC resonant converter according to claim 3, characterized in that, In the simultaneous charging mode: The input port receives DC power, the high-voltage port outputs high-voltage DC power, and the low-voltage port outputs low-voltage DC power. At this time, a hybrid frequency-phase shift control strategy is adopted for the high-voltage port to adjust the operating frequency and phase shift angle of the full-bridge network at the input port in order to control the output voltage of the high-voltage port. A PWM control strategy is adopted for the low-voltage port. By independently adjusting the duty cycle of the MOSFET in the Buck regulator network on the low-voltage side, the output voltage of the low-voltage port is controlled, thereby achieving independent and precise voltage regulation of the two ports.

9. The control method for an OBC-LDC integrated three-port LLC resonant converter according to claim 3, characterized in that, Meanwhile, the coordinated design of the charging mode at the control level is as follows: Regarding timing coordination, the low-voltage side Buck switch S buck The turn-on timing of the transistor and the primary-side MOSFET have a strict phase match, and the phase match includes S... buck It is turned on during the primary side conduction period and turned off synchronously with the primary side during the primary side dead time to avoid the dead time voltage drop causing disturbance to the low voltage port. In terms of power decoupling, the power flow at the high-voltage port is independently determined by the input port frequency-phase shift control, while the power flow at the low-voltage port is independently determined by the Buck-side PWM. The two control loops do not interfere with each other. In terms of disturbance suppression, through timing coordination, even if the load on the high-voltage side changes abruptly, the output voltage of the low-voltage port will not be affected by coupling.

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