A magnetically integrated planar transformer based on CLLC converter and a control method thereof

Abstract

The present invention discloses a magnetically integrated planar transformer based on a CLLC converter and a control method thereof, and relates to the technical field of transformers; the transformer comprises an input side, an inverter network, a resonant cavity, a rectifier network and an output side; the working mode of the inverter network can be changed by changing the state of a switch tube in the inverter network; the topological structure of the rectifier network can be changed by changing the states of two switch tubes in the rectifier network; by regulating the working mode of the inverter network and the topological structure of the rectifier network, a variety of transformer working modes can be configured to adjust the output voltage, and the switching frequency of the transformer can be limited to a preset frequency range while expanding the voltage gain range, so that the switching frequency varies within a narrower range, reducing the efficiency loss caused by a large range of frequency changes, thereby improving the efficiency of the transformer.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and in particular to a magnetically integrated planar transformer based on a CLLC converter and a control method thereof. Background Art

[0002] In high-efficiency power electronic systems, CLLC converters are favored for their wide voltage gain adjustment range and high power density. However, in order to achieve these performance goals, the magnetic components and control strategies in the converter system need to be precisely coordinated. As a new type of magnetic component, the magnetically integrated planar transformer provides a superior solution for CLLC converters with its compact and efficient design concept, but also introduces new control challenges.

[0003] The control method of the CLLC converter must consider the operating frequency and magnetic field characteristics of the transformer. Since the structure of the planar transformer gives it lower losses and better thermal management at high frequencies, the control strategy needs to dynamically adjust the frequency to ensure that the transformer can maintain efficient operation under different load and input conditions. To achieve this, the commonly used control system usually adopts a frequency-based regulation method to optimize the magnetic performance of the transformer by accurately controlling the switching frequency and phase. However, in the case of excessive input voltage and extremely low voltage gain or light load conditions, in order to achieve the purpose of controlling the output voltage, the switching frequency may be far away from the resonant frequency. One of the core advantages of the resonant converter design is its high efficiency, especially near the resonant frequency. If the switching frequency is far away from the resonant frequency, the low switching loss and high efficiency characteristics near the resonant frequency will not be effectively utilized, and the efficiency of the converter will be significantly reduced. Summary of the invention

[0004] The purpose of the present invention is to solve the problem mentioned in the background technology that the switching frequency is far away from the resonant frequency, resulting in reduced efficiency, and to propose a magnetically integrated planar transformer based on a CLLC converter and a control method thereof.

[0005] In a first aspect of the present invention, there is provided a magnetically integrated planar transformer based on a CLLC converter, the transformer comprising:

[0006] Input side, inverter network, resonant cavity, rectifier network and output side; the input side includes input voltage V in and capacitor C i The inverter network is composed of switch tube S1, switch tube S2, switch tube S3 and switch tube S4; the resonant cavity includes a primary side and a secondary side; the primary side includes a capacitor C r1 、Inductance L r1 , Excitation inductance L m and the primary winding; the secondary side includes a capacitor C r2、Inductance L r2 and secondary winding;

[0007] The rectifier network is composed of switch tube S5, switch tube S6, switch tube S7, switch tube S8, switch tube S9, switch tube S 10 、Diode D o1 and diode D o2 Composition; the output side includes a capacitor C oL , capacitor C oH and output voltage V out ;in:

[0008] One end of the secondary side is connected to one end of the switch tube S5 and one end of the switch tube S6 respectively; the capacitor C oH One end of the switch tube S5 and the other end of the diode D o1 The other end of the switch tube S6 is connected to one end of the switch tube S9 and the diode D o2 The output terminal connection of

[0009] The other end of the secondary side is connected to one end of the switch tube S7 and one end of the switch tube S8 respectively; the capacitor C oL One end of the switch tube S8 and the other end of the diode D o2 The other end of the switch tube S7 is connected to one end of the switch tube S10 and the diode D o1 The input terminal connection of

[0010] The other end of the switch tube S9, the other end of the switch tube S10, the capacitor C oL The other end and the capacitor C oH The other ends are connected to each other.

[0011] Optionally, the inverter network includes two operating modes, namely full-bridge mode and half-bridge mode; wherein:

[0012] In the full-bridge mode, the control signals of the switch tube S1 and the switch tube S4 are consistent; the control signals of the switch tube S2 and the switch tube S3 are consistent; the control signals of the switch tube S1 and the switch tube S2 are complementary;

[0013] In the half-bridge mode, the switch tube S2 remains turned off; the switch tube S4 remains turned on; and the control signals of the switch tube S1 and the switch tube S3 are complementary.

[0014] Optionally, the rectifier network includes two topological structures, namely a first topological structure and a second topological structure; wherein:

[0015] In the first topology structure, the switch tube S9 and the switch tube S10 remain turned on;

[0016] In the second topology, the switch S9 and the switch S10 remain turned off.

[0017] Optionally, the transformer includes multiple working modes, including:

[0018] Mode 1: The inverter network operates in full-bridge mode, and the rectifier network maintains the first topology; the output voltage is adjusted by PFM;

[0019] Mode 2: The inverter network operates in full-bridge mode, and the topology of the rectifier network is controlled by PWM signals; the output voltage is adjusted by PFM;

[0020] Mode 3: The inverter network operates in half-bridge mode, and the rectifier network maintains the first topology; the output voltage is adjusted by PFM;

[0021] Mode 4: The inverter network operates in half-bridge mode, and the topology of the rectifier network is controlled by PWM signals; the output voltage is adjusted by PFM;

[0022] Mode 5: The inverter network operates in half-bridge mode, and the rectifier network maintains the second topology; the output voltage is adjusted by PFM;

[0023] Mode 6: The inverter network operates in half-bridge mode, and the rectifier network maintains the second topology; the output voltage is adjusted by APWM.

[0024] A second aspect of the present invention provides a control method for a magnetically integrated planar transformer based on a CLLC converter, the method comprising:

[0025] During the startup phase, the target output voltage and the source input voltage are obtained;

[0026] Calculating a target gain value according to the target output voltage and the source input voltage;

[0027] According to the target gain value, query a preset gain comparison table to determine the target operating mode of the transformer;

[0028] According to the target working mode, determining the working mode of the inverter network of the transformer and the topological structure of the rectifier network;

[0029] The transformer is started according to a preset soft start frequency, and the switching frequency is linearly reduced until the output voltage reaches the target output voltage.

[0030] Optionally, starting the transformer according to a preset soft start frequency and linearly reducing the switching frequency until the output voltage reaches the target output voltage includes:

[0031] If the inverter network is in half-bridge mode in the target working mode, the preset soft start frequency is used as the switching frequency, and the duty cycle of the switch tube S1 is linearly increased from 0 to 0.5; the duty cycle of the switch tube S4 is maintained at 1; the switch tube S1 and the switch tube S3 are complementary turned on;

[0032] When the duty cycle of the switch tube S1 increases to 0.5, the duty cycles of the switch tubes S1 and S3 are kept at 0.5, and the switching frequency is linearly reduced until the output voltage reaches the target output voltage;

[0033] If the inverter network is in full-bridge mode in the target working mode, the preset soft start frequency is used as the switching frequency, and the duty cycle of the switch tube S1 is linearly increased from 0 to 0.5; the duty cycle of the switch tube S4 is maintained at 1; the switch tube S1 and the switch tube S3 are complementary turned on;

[0034] When the duty cycle of the switch tube S1 increases to 0.5, the switching frequency is kept unchanged at the soft start frequency, the duty cycles of the switch tubes S1 and S3 are kept unchanged at 0.5, and the duty cycle of the switch tube S4 is linearly reduced from 1 to 0.5; the switch tube S4 and the switch tube S2 are complementary turned on;

[0035] When the duty cycle of the switch tube S4 is reduced to 0.5, the duty cycles of the switch tubes S1, S2, S3 and S4 are kept unchanged at 0.5, and the switching frequency is linearly reduced until the output voltage reaches the target voltage.

[0036] Beneficial effects of the present invention:

[0037] The present invention proposes a magnetic integrated planar transformer based on a CLLC converter, the transformer comprising: an input side, an inverter network, a resonant cavity, a rectifier network and an output side; the input side comprises an input voltage V in and capacitor C i ; The inverter network is composed of switch tube S1, switch tube S2, switch tube S3 and switch tube S4; The resonant cavity includes a primary side and a secondary side; The primary side includes a capacitor C r1 、Inductance L r1 , Excitation inductance L m and the primary winding; the secondary side includes capacitor C r2 、Inductance L r2 and the secondary winding; the rectifier network consists of switch tube S5, switch tube S6, switch tube S7, switch tube S8, switch tube S9, switch tube S10 、Diode D o1 and diode D o2 Composition; the output side includes capacitor C oL , capacitor C oH and output voltage V out ; Wherein: one end of the secondary side is connected to one end of the switch tube S5 and one end of the switch tube S6 respectively; capacitor C oH One end of the switch tube S5 and the other end of the diode D o1 The other end of the switch tube S6 is connected to one end of the switch tube S9 and the diode D o2 The other end of the secondary side is connected to one end of the switch tube S7 and one end of the switch tube S8 respectively; the capacitor C oL One end of the switch tube S8 and the other end of the diode D o2 The other end of the switch tube S7 is connected to one end of the switch tube S10 and the diode D o1 The other end of the switch tube S9, the other end of the switch tube S10, and the capacitor C oL The other end and capacitor C oH The other ends are connected to each other.

[0038] By adjusting the working mode of the inverter network and the topological structure of the rectifier network, and configuring a variety of converter working modes to adjust the output voltage, the switching frequency of the converter can be limited to a preset frequency range while expanding the voltage gain range. The switching frequency can vary within a narrower range, reducing the efficiency loss caused by large-range frequency changes, thereby improving the efficiency of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be further described below in conjunction with the accompanying drawings.

[0040] Figure 1 A topological diagram of a magnetically integrated planar transformer based on a CLLC converter is provided for an embodiment of the present invention;

[0041] Figure 2 A flow chart of a magnetically integrated planar transformer control method based on a CLLC converter is provided for an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The embodiment of the present invention provides a magnetic integrated planar transformer based on a CLLC converter. Figure 1 , Figure 1 A topological diagram of a magnetically integrated planar transformer based on a CLLC converter provided in an embodiment of the present invention. The transformer comprises:

[0044] Input side, inverter network, resonant cavity, rectifier network and output side; the input side includes input voltage V in and capacitor C i ; The inverter network is composed of switch tube S1, switch tube S2, switch tube S3 and switch tube S4; The resonant cavity includes a primary side and a secondary side; The primary side includes a capacitor C r1 、Inductance L r1 , Excitation inductance L m and the primary winding; the secondary side includes capacitor C r2 、Inductance L r2 and secondary winding;

[0045] The rectifier network consists of switch tube S5, switch tube S6, switch tube S7, switch tube S8, switch tube S9, switch tube S 10 、Diode D o1 and diode D o2 Composition; the output side includes capacitor C oL , capacitor C oH and output voltage V out ;in:

[0046] One end of the secondary side is connected to one end of the switch tube S5 and one end of the switch tube S6 respectively; the capacitor C oH One end of the switch tube S5 and the other end of the diode D o1 The other end of the switch tube S6 is connected to one end of the switch tube S9 and the diode D o2 The output terminal connection of

[0047] The other end of the secondary side is connected to one end of the switch tube S7 and one end of the switch tube S8 respectively; the capacitor C oL One end of the switch tube S8 and the other end of the diode D o2 The other end of the switch tube S7 is connected to one end of the switch tube S10 and the diode D o1 The input terminal connection of

[0048] The other end of the switch tube S9, the other end of the switch tube S10, the capacitor C oL The other end and capacitor C oH The other ends are connected to each other.

[0049] Based on a magnetically integrated planar transformer based on a CLLC converter provided in an embodiment of the present invention, by regulating the working mode of the inverter network and the topological structure of the rectifier network, a variety of converter working modes are configured to adjust the output voltage. While expanding the voltage gain range, the switching frequency of the converter can be limited to a preset frequency range, so that the switching frequency varies within a narrower range, reducing the efficiency loss caused by large-range frequency changes, thereby improving the efficiency of the converter.

[0050] In one embodiment, the inverter network includes two working modes, namely full-bridge mode and half-bridge mode; wherein:

[0051] In the full-bridge mode, the control signals of the switch tube S1 and the switch tube S4 are consistent; the control signals of the switch tube S2 and the switch tube S3 are consistent; and the control signals of the switch tube S1 and the switch tube S2 are complementary.

[0052] In the half-bridge mode, the switch tube S2 remains off; the switch tube S4 remains on; and the control signals of the switch tubes S1 and S3 are complementary.

[0053] In one implementation, in full-bridge mode, the control signals of switches S1, S4, S5, and S8 are consistent; the control signals of switches S2, S3, S6, and S7 are consistent. In half-bridge mode, the control signals of S1, S5, and S8 are consistent; the control signals of S6 and S7 are consistent and complementary to the control signal of S5.

[0054] In one implementation, when the converter is lightly loaded or has low power consumption requirements, and / or the input voltage of the transformer is a high-level voltage, the half-bridge mode is used to provide sufficient power output while maintaining high efficiency, avoiding energy waste that may occur in the full-bridge mode. When in a scenario where high power transmission is required, the full-bridge mode is used to output higher power. By switching between full-bridge and half-bridge modes in different working scenarios, the working state of the transformer can be flexibly adjusted according to actual needs to achieve the optimal balance between power transmission efficiency and reliability.

[0055] In one implementation, the full-bridge mode and the half-bridge mode are used in combination to expand the voltage gain range of the transformer.

[0056] In one embodiment, the rectifier network includes two topological structures, namely a first topological structure and a second topological structure; wherein:

[0057] In the first topology structure, the switch tube S9 and the switch tube S10 remain turned on.

[0058] In the second topology, the switch S9 and the switch S10 remain turned off.

[0059] In one implementation, the first topology can achieve voltage amplification and rectification, and the second topology can achieve full-wave rectification. When combined with the working mode of the inverter network, a more complex gain effect can be achieved.

[0060] In one embodiment, the transformer includes multiple operating modes; including:

[0061] Mode 1: The inverter network operates in full-bridge mode, and the rectifier network maintains the first topology; the output voltage is regulated by PFM (pulse frequency modulation).

[0062] Mode 2: The inverter network operates in full-bridge mode, and the topology of the rectifier network is controlled by a PWM (pulse width modulation) signal; the output voltage is adjusted by PFM.

[0063] Mode 3: The inverter network operates in half-bridge mode, and the rectifier network maintains the first topology; the output voltage is adjusted by PFM.

[0064] Mode 4: The inverter network operates in half-bridge mode, and the topology of the rectifier network is controlled by a PWM signal; the output voltage is adjusted by PFM.

[0065] Mode 5: The inverter network operates in half-bridge mode, and the rectifier network maintains the second topology; the output voltage is regulated by PFM.

[0066] Mode 6: The inverter network operates in half-bridge mode, and the rectifier network maintains the second topology; the output voltage is adjusted by APWM (adaptive pulse width modulation).

[0067] In one implementation, multiple working modes provide flexible choices and can be configured according to different application scenarios and requirements.

[0068] In mode 1, the inverter network operates in full-bridge mode. The full-bridge inverter circuit has higher output voltage and current capabilities and is suitable for scenarios that require high power output. PFM regulation can adjust the output voltage by changing the pulse frequency without changing the pulse width, which helps to achieve more efficient energy transmission in some application scenarios.

[0069] In mode 2, the PWM signal is used to control the on and off of the switch tubes S9 and S10 to achieve the topology transformation of the rectifier network. PWM control provides more flexible adjustment capabilities for the rectifier network topology structure, and can dynamically change the topology structure according to actual needs to adapt to different load characteristics and working environments. Compared with mode 1, a lower voltage gain can be achieved within the preset frequency range.

[0070] In mode 3, the inverter network operates in half-bridge mode, which can achieve lower voltage gain compared to mode 1.

[0071] In mode 4, a lower voltage gain than mode 3 can be achieved by combining half-bridge mode and PWM regulation.

[0072] In mode 5, the second topology of the rectifier network reduces the cut-off time of the current and reduces power loss, thereby improving the overall conversion efficiency. At the same time, compared with mode 4, it has a lower voltage gain within the preset frequency range.

[0073] In mode 6, the duty cycle is controlled by APWM to keep the switching frequency at the upper limit of the preset range, which can achieve a lower voltage gain than mode 5.

[0074] By changing and selecting a variety of topological structures, it is possible to achieve extremely low voltage gain under light load conditions without excessively increasing the switching frequency, thereby improving conversion efficiency.

[0075] The embodiment of the present invention provides a control method for a magnetically integrated planar transformer based on a CLLC converter. Figure 2 , Figure 2 A flow chart of a magnetic integrated planar transformer control method based on a CLLC converter is provided in an embodiment of the present invention. The method comprises:

[0076] Step 1: During the startup phase, the target output voltage and the source input voltage are obtained.

[0077] Step 2: Calculate the target gain value based on the target output voltage and the source input voltage.

[0078] Step three: According to the target gain value, query the preset gain comparison table to determine the target operating mode of the transformer.

[0079] Step 4: Determine the working mode of the inverter network of the transformer and the topology of the rectifier network according to the target working mode.

[0080] Step 5: Start the transformer according to the preset soft start frequency and linearly reduce the switching frequency until the output voltage reaches the target output voltage.

[0081] In one implementation, by querying a preset gain comparison table and determining the target operating mode, the method can achieve precise control of the transformer over a wide voltage gain range. This means that whether in boost mode or buck mode, the transformer can effectively adjust the output voltage to meet different usage scenarios.

[0082] In one implementation, a multi-mode composite control strategy is combined to limit the switching frequency within a preset frequency range under different voltage and load conditions, thereby reducing the losses of the converter and improving the overall efficiency of the transformer.

[0083] In one embodiment, a method for obtaining a gain comparison table includes:

[0084] In the circuit simulation environment, build transformer topologies in different modes;

[0085] For Mode 1, Mode 3, and Mode 5, the duty cycle of the switch in the inverter network is kept unchanged at 0.5, and simulation experiments are performed by only changing the switching frequency to obtain the voltage gain curves under different topological conditions;

[0086] For mode 2 and mode 4, by changing the duty cycle of switch tube S9 and switch tube S10, simulation experiments are carried out to obtain voltage gain curves under different duty cycle conditions;

[0087] Among them, mode 1 is equivalent to the case where the duty cycle is 1 in mode 2; mode 3 is equivalent to the case where the duty cycle is 1 in mode 4; mode 5 is equivalent to the case where the duty cycle is 0 in mode 4.

[0088] Segments of multiple voltage gain curves within a preset frequency range are intercepted to extract voltage gain ranges that can be achieved in different modes within the preset frequency range, and a gain comparison table is established according to the voltage gain ranges of different modes.

[0089] In one embodiment, starting the transformer according to a preset soft start frequency and linearly reducing the switching frequency until the output voltage reaches a target output voltage includes:

[0090] Case 1: If the inverter network is in half-bridge mode in the target working mode, the preset soft start frequency is used as the switching frequency, and the duty cycle of the switch tube S1 is linearly increased from 0 to 0.5; the duty cycle of the switch tube S4 is maintained at 1; the switch tubes S1 and S3 are complementary turned on.

[0091] When the duty cycle of the switch tube S1 increases to 0.5, the duty cycles of the switch tubes S1 and S3 are kept unchanged at 0.5, and the switching frequency is linearly reduced until the output voltage reaches the target output voltage.

[0092] Case 2: If the inverter network is in full-bridge mode in the target working mode, the preset soft start frequency is used as the switching frequency, and the duty cycle of the switch tube S1 is linearly increased from 0 to 0.5; the duty cycle of the switch tube S4 is maintained at 1; the switch tubes S1 and S3 are complementary turned on.

[0093] When the duty cycle of the switch tube S1 increases to 0.5, the switching frequency is kept at the soft start frequency, the duty cycles of the switch tubes S1 and S3 are kept at 0.5, and the duty cycle of the switch tube S4 is linearly reduced from 1 to 0.5; the switch tube S4 and the switch tube S2 are complementary to each other.

[0094] When the duty cycle of the switch tube S4 is reduced to 0.5, the duty cycles of the switch tubes S1, S2, S3 and S4 are kept unchanged at 0.5, and the switching frequency is linearly reduced until the output voltage reaches the target voltage.

[0095] In one implementation, starting the transformer with a preset soft start frequency can effectively avoid the impact on circuit components caused by the sudden change of current or voltage at the moment of startup. This method of gradually increasing or decreasing the operating frequency and duty cycle can smoothly transition to a stable working state, extend the life of the equipment, and reduce the failure rate. Among them, the soft start frequency is a higher frequency, which can provide a higher impedance at startup.

[0096] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A magnetically integrated planar transformer based on a CLLC converter, the transformer comprising an input side, an inverter network, a resonant cavity, a rectifier network and an output side; the input side comprises an input voltage V in and capacitor C i The inverter network is composed of switch tube S1, switch tube S2, switch tube S3 and switch tube S4; the resonant cavity includes a primary side and a secondary side; the primary side includes a capacitor C r1 、Inductance L r1 , Excitation inductance L m and the primary winding; the secondary side includes a capacitor C r2 、Inductance L r2 and secondary winding; It is characterized in that The rectifier network is composed of switch tube S5, switch tube S6, switch tube S7, switch tube S8, switch tube S9, switch tube S10, diode D o1 and diode D o2 Composition; the output side includes a capacitor C oL , capacitor C oH and output voltage V out ;in: One end of the secondary side is connected to one end of the switch tube S5 and one end of the switch tube S6 respectively; the capacitor C oH One end of the switch tube S5 and the other end of the diode D o1 The other end of the switch tube S6 is connected to one end of the switch tube S9 and the diode D o2 The output terminal connection of The other end of the secondary side is connected to one end of the switch tube S7 and one end of the switch tube S8 respectively; the capacitor C oL One end of the switch tube S8 and the other end of the diode D o2 The other end of the switch tube S7 is connected to one end of the switch tube S10 and the diode D o1 The input terminal connection of The other end of the switch tube S9, the other end of the switch tube S10, the capacitor C oL The other end and the capacitor C oH The other ends are connected to each other; The inverter network includes two working modes, namely full-bridge mode and half-bridge mode; wherein: In the full-bridge mode, the control signals of the switch tube S1 and the switch tube S4 are consistent; the control signals of the switch tube S2 and the switch tube S3 are consistent; the control signals of the switch tube S1 and the switch tube S2 are complementary; In the half-bridge mode, the switch tube S2 remains turned off; the switch tube S4 remains turned on; and the control signals of the switch tube S1 and the switch tube S3 are complementary.

2. The magnetic integrated planar transformer based on CLLC converter according to claim 1, characterized in that: The rectifier network includes two topological structures, namely a first topological structure and a second topological structure; wherein: In the first topology structure, the switch tube S9 and the switch tube S10 remain turned on; In the second topology, the switch S9 and the switch S10 remain turned off.

3. The magnetic integrated planar transformer based on CLLC converter according to claim 2, characterized in that: The transformer includes multiple working modes; These include: Mode 1: The inverter network operates in full-bridge mode, and the rectifier network maintains the first topology; the output voltage is adjusted by PFM; Mode 2: The inverter network operates in full-bridge mode, and the topology of the rectifier network is controlled by PWM signals; the output voltage is adjusted by PFM; Mode 3: The inverter network operates in half-bridge mode, and the rectifier network maintains the first topology; the output voltage is adjusted by PFM; Mode 4: The inverter network operates in half-bridge mode, and the topology of the rectifier network is controlled by PWM signals; the output voltage is adjusted by PFM; Mode 5: The inverter network operates in half-bridge mode, and the rectifier network maintains the second topology; the output voltage is adjusted by PFM; Mode 6: The inverter network operates in half-bridge mode, and the rectifier network maintains the second topology; the output voltage is adjusted by APWM.

4. A control method for a magnetically integrated planar transformer based on a CLLC converter, characterized in that: Based on the magnetically integrated planar transformer based on the CLLC converter according to claim 1, the method comprises: During the startup phase, the target output voltage and the source input voltage are obtained; Calculating a target gain value according to the target output voltage and the source input voltage; According to the target gain value, query a preset gain comparison table to determine the target operating mode of the transformer; According to the target working mode, determining the working mode of the inverter network of the transformer and the topological structure of the rectifier network; The transformer is started according to a preset soft start frequency, and the switching frequency is linearly reduced until the output voltage reaches the target output voltage.

5. The control method of a magnetic integrated planar transformer based on a CLLC converter according to claim 4, characterized in that: The step of starting the transformer according to a preset soft start frequency and linearly reducing the switching frequency until the output voltage reaches the target output voltage includes: If the inverter network is in half-bridge mode in the target working mode, the preset soft start frequency is used as the switching frequency, and the duty cycle of the switch tube S1 is linearly increased from 0 to 0.5; the duty cycle of the switch tube S4 is maintained at 1; the switch tube S1 and the switch tube S3 are complementary turned on; When the duty cycle of the switch tube S1 increases to 0.5, the duty cycles of the switch tubes S1 and S3 are kept at 0.5, and the switching frequency is linearly reduced until the output voltage reaches the target output voltage; If the inverter network is in full-bridge mode in the target working mode, the preset soft start frequency is used as the switching frequency, and the duty cycle of the switch tube S1 is linearly increased from 0 to 0.5; the duty cycle of the switch tube S4 is maintained at 1; the switch tube S1 and the switch tube S3 are complementary turned on; When the duty cycle of the switch tube S1 increases to 0.5, the switching frequency is kept unchanged at the soft start frequency, the duty cycles of the switch tubes S1 and S3 are kept unchanged at 0.5, and the duty cycle of the switch tube S4 is linearly reduced from 1 to 0.5; the switch tube S4 and the switch tube S2 are complementary turned on; When the duty cycle of the switch tube S4 is reduced to 0.5, the duty cycles of the switch tubes S1, S2, S3 and S4 are kept unchanged at 0.5, and the switching frequency is linearly reduced until the output voltage reaches the target voltage.

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