LLC-buck hybrid topology circuit and control method

Abstract

The application relates to the technical field of hybrid topology circuit control, in particular to an LLC-Buck hybrid topology circuit and a control method; the working state of an LLC circuit is adjusted according to a feedback adjustment amount and an LLC working frequency to obtain a first voltage gain value; a PWM conduction instruction is generated according to a preset theoretical high-frequency resonance period and the first voltage gain value; LLC upper bridge arm switch tubes and LLC lower bridge arm switch tubes are controlled to be conducted according to the PWM conduction instruction; a BUCK bridge arm switch tube group is controlled to be subjected to pulse width regulation according to a PWM pulse width instruction; the scheme realizes full-condition adaptation under heavy load and light load, adapts to needs such as vehicle-mounted storage battery energy compensation, has strong anti-interference performance, stably operates under a wide temperature environment, guarantees smooth power supply of vehicle-mounted equipment, and improves the efficiency, stability and engineering landing value of the hybrid topology circuit.

Description

Technical Field

[0001] This invention relates to the field of hybrid topology circuit control technology, and more particularly to an LLC-Buck hybrid topology circuit and its control method. Background Technology

[0002] In a three-in-one on-board charger system, the core requirement is to convert AC power into high-voltage DC and low-voltage DC power to supply the BMS battery pack and 14V battery, respectively. Cascaded LLC and BUCK topologies are a mature implementation solution in the industry. However, existing technologies have significant bottlenecks: while keeping the circuit continuously operational can prevent transformer whistling, the output voltage cannot be effectively suppressed under no-load or light-load conditions, easily leading to overshoot, which may damage circuit components and even affect the safe operation of subsequent energy storage devices such as the BMS or battery. Furthermore, traditional whistling control strategies easily cause low-frequency whistling in the transformer under light load due to the imbalance of charging and discharging of the energy storage inductor, and this whistling is difficult to avoid through mechanical structure or hardware adjustments. As major automakers continuously increase their requirements for equipment operating noise and light-load efficiency, whistling control can no longer simultaneously meet both core indicators. Therefore, it is urgent to develop new control strategies to complement existing cascaded circuits and optimize parameter indicators. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide an LLC-Buck hybrid topology circuit and control method.

[0004] An LLC-Buck hybrid topology circuit includes: an LLC circuit, a BUCK circuit, and a load; the output terminal of the LLC circuit is connected to the input terminal of the BUCK circuit, and the output terminal of the BUCK circuit is connected to the input terminal of the load; the LLC circuit includes an LLC transformer primary winding, an LLC rectifier circuit, an LLC transformer secondary winding, an LLC upper bridge arm switch, and an LLC lower bridge arm switch; the LLC upper bridge arm switch is connected in series with the LLC transformer primary winding, and the LLC transformer primary winding transfers energy to the load via electromagnetic induction coupling. The LLC rectifier circuit is connected in series with the secondary winding of the LLC transformer, and the lower bridge arm switch of the LLC transformer is connected in series with the secondary winding of the LLC transformer. The BUCK circuit includes a BUCK converter, a BUCK rectifier circuit, and a BUCK bridge arm switch group. The output terminal of the secondary winding of the LLC transformer is connected to the input terminal of the BUCK rectifier circuit, the BUCK rectifier circuit is connected in series with the BUCK converter, the BUCK bridge arm switch group is connected in series with the BUCK converter, and the output terminal of the BUCK converter is connected to the load.

[0005] Furthermore, applied to an LLC-Buck hybrid topology circuit as described above, the LLC-Buck hybrid topology circuit control method includes: analyzing the load output terminal of the LLC-Buck hybrid topology circuit to obtain the load power; analyzing the load power according to a preset first monitoring condition and a preset first power threshold to obtain a feedback adjustment amount; acquiring the LLC operating frequency, and adjusting the operating state of the LLC circuit according to the feedback adjustment amount and the LLC operating frequency to obtain a first voltage gain value; generating a PWM turn-on command according to a preset theoretical high-frequency resonant period and the first voltage gain value; controlling the LLC upper bridge arm switch and the LLC lower bridge arm switch to turn on according to the PWM turn-on command; analyzing the load power according to a preset second monitoring condition and a preset second power threshold to obtain a PWM pulse width command; and controlling the BUCK bridge arm switch group to perform pulse width adjustment according to the PWM pulse width command.

[0006] Furthermore, the LLC-Buck hybrid topology circuit also includes a current sensor and a voltage sensor. The analysis of the load output terminal of the LLC-Buck hybrid topology circuit to obtain the load power includes: controlling the current sensor to sample the current at the load output terminal of the LLC-Buck hybrid topology circuit according to a preset sampling frequency to obtain the load current value; controlling the voltage sensor to sample the voltage at the load output terminal of the LLC-Buck hybrid topology circuit according to the sampling frequency to obtain the load voltage value; and multiplying the load current and load voltage values ​​to obtain the load power.

[0007] Further, the step of analyzing the load power according to the preset first monitoring conditions and the preset first power threshold to obtain the feedback adjustment amount includes: determining whether the load power is greater than or equal to the first power threshold; when the load power is greater than or equal to the first power threshold, generating a heavy load jump direction; collecting the operating time of the LLC-Buck hybrid topology circuit under the load power according to the first monitoring conditions to obtain the first abnormal operating time; obtaining the current LLC duty cycle, and generating the feedback adjustment amount according to the heavy load jump direction, the first abnormal operating time, and the current LLC duty cycle.

[0008] Further, the step of adjusting the operating state of the LLC circuit according to the feedback adjustment amount and the LLC operating frequency to obtain the first voltage gain value includes: adjusting the LLC operating frequency according to the feedback adjustment amount to obtain a first target frequency; adjusting the operating state of the LLC circuit according to the first target frequency to obtain a first operating state; in the first operating state, acquiring the LLC secondary-side rectified output voltage and the LLC primary-side equivalent input voltage; and calculating the ratio of the LLC secondary-side rectified output voltage and the LLC primary-side equivalent input voltage to obtain the first voltage gain value.

[0009] Further, the step of analyzing the load power according to the preset second monitoring conditions and the preset second power threshold to obtain the PWM pulse width command includes: analyzing the load power according to the second monitoring conditions and the second power threshold to obtain the feedforward adjustment amount; obtaining the BUCK operating frequency and adjusting the BUCK operating frequency according to the feedforward adjustment amount to obtain the second target frequency; adjusting the BUCK operating state according to the second target frequency to obtain the second operating state; in the second operating state, obtaining the BUCK secondary-side rectified output voltage and the BUCK primary-side equivalent input voltage; calculating the ratio of the BUCK secondary-side rectified output voltage and the BUCK primary-side equivalent input voltage to obtain the second voltage gain value; and generating the PWM pulse width command according to the preset theoretical low-frequency resonance period and the second voltage gain value.

[0010] Further, the step of generating a PWM turn-on command based on a preset theoretical high-frequency resonant period and a first voltage gain value includes: acquiring the resonant current signal of the LLC circuit according to a preset sampling period to obtain a first resonant current signal; performing waveform analysis on the first resonant current signal to obtain the actual high-frequency resonant period; performing deviation analysis on the theoretical high-frequency resonant period and the actual high-frequency resonant period to obtain a first deviation analysis result; calibrating the preset wave-blocking resonant parameters according to the first deviation analysis result and the first voltage gain value to obtain a first calibrated resonant parameter; and generating a PWM turn-on command according to the first calibrated resonant parameter.

[0011] Further, the step of analyzing the load power based on the second monitoring conditions and the second power threshold to obtain the feedforward adjustment includes: determining whether the load power is less than or equal to the second power threshold; when the load power is less than or equal to the second power threshold, generating a light load jump direction; acquiring the operating time of the LLC-Buck hybrid topology circuit under the load power based on the second monitoring conditions to obtain the second abnormal operating time; obtaining the BUCK duty cycle, and generating the feedforward adjustment based on the light load jump direction, the second abnormal operating time, and the BUCK duty cycle.

[0012] Further, the step of generating a PWM pulse width command based on a preset theoretical low-frequency resonant period and a second voltage gain value includes: acquiring the resonant current signal of the BUCK circuit according to a sampling period to obtain a second resonant current signal; performing waveform analysis on the second resonant current signal to obtain the actual low-frequency resonant period; performing deviation analysis on the theoretical low-frequency resonant period and the actual low-frequency resonant period to obtain a second deviation analysis result; calibrating the preset start-up resonant parameters based on the second deviation analysis result and the second voltage gain value to obtain a second calibration resonant parameter; and generating a PWM pulse width command based on the preset natural frequency and the second calibration resonant parameter.

[0013] The beneficial effects of an LLC-Buck hybrid topology circuit in the technical solution of this invention are as follows:

[0014] Employing an LLC-Buck hybrid topology, the LLC circuit transmits power at high frequency, while electromagnetic coupling between the primary and secondary windings enhances transmission efficiency. The series connection of the upper and lower bridge arm switches facilitates zero-voltage switching (ZVS), reducing switching losses under high-frequency conditions. The series connection of the LLC and BUCK dual rectifier circuits filters high-frequency ripple, providing a stable input for the step-down stage. The BUCK circuit precisely regulates the voltage through the converter and the bridge arm switch group, ensuring stable output voltage for the load. The overall topology module is adapted to the small size and high power density requirements of on-board chargers, featuring low operating noise, strong electromagnetic interference resistance, and adaptability to wide temperature environments, effectively extending device lifespan and providing efficient, smooth, and reliable power supply for on-board equipment.

[0015] The beneficial effects of a control method for LLC-Buck hybrid topology circuits:

[0016] In heavy-load scenarios, a feedback adjustment is generated through load power analysis to dynamically optimize the LLC circuit's operating state and generate a PWM turn-on command. This precisely controls the upper and lower bridge arm switches of the LLC to achieve zero-voltage switching (ZVS), improving heavy-load energy conversion efficiency and reducing switching losses. It also stabilizes the resonant cavity's operating state, avoiding resonance mismatch and high-frequency oscillations, suppressing transformer noise, and providing accurate output voltage with low ripple. It also exhibits outstanding resistance to temperature drift and component aging. In light-load scenarios, a PWM pulse width command is generated based on a second monitoring condition and power threshold to control the Buck switch for pulse width adjustment. This avoids low-frequency howling bands, quickly responds to light-load fluctuations, and reduces voltage ripple. This solution achieves full-condition adaptation from heavy to light loads, meets the needs of vehicle battery charging, has strong anti-interference capabilities, operates stably in a wide temperature range, ensures smooth power supply to vehicle equipment, and enhances the efficiency, stability, and engineering application value of hybrid topology circuits. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0018] Figure 1 This is a first flowchart of a control method for an LLC-Buck hybrid topology circuit provided in an embodiment of the present invention;

[0019] Figure 2 This is a second flowchart of a control method for an LLC-Buck hybrid topology circuit provided in an embodiment of the present invention;

[0020] Figure 3 A third flowchart of an LLC-Buck hybrid topology circuit control method provided in an embodiment of the present invention;

[0021] Figure 4 A fourth flowchart of an LLC-Buck hybrid topology circuit control method provided in an embodiment of the present invention;

[0022] Figure 5 A fifth flowchart of an LLC-Buck hybrid topology circuit control method provided in an embodiment of the present invention;

[0023] Figure 6 A sixth flowchart of an LLC-Buck hybrid topology circuit control method provided in an embodiment of the present invention;

[0024] Figure 7 A seventh flowchart of an LLC-Buck hybrid topology circuit control method provided in an embodiment of the present invention;

[0025] Figure 8 This is an eighth flowchart of an LLC-Buck hybrid topology circuit control method provided in an embodiment of the present invention;

[0026] Figure 9 This is a schematic diagram of an LLC-Buck hybrid topology circuit provided in an embodiment of the present invention. Detailed Implementation

[0027] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" or "having" and any variations thereof are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] An LLC-Buck hybrid topology circuit includes: an LLC circuit, a BUCK circuit, and a load; the output terminal of the LLC circuit is connected to the input terminal of the BUCK circuit, and the output terminal of the BUCK circuit is connected to the input terminal of the load; the LLC circuit includes an LLC transformer primary winding, an LLC rectifier circuit, an LLC transformer secondary winding, an LLC upper bridge arm switch, and an LLC lower bridge arm switch; the LLC upper bridge arm switch is connected in series with the LLC transformer primary winding to directly control the primary energy input timing; the LLC transformer primary winding transfers energy to the LLC rectifier circuit through electromagnetic induction coupling, matching the high-frequency operating characteristics (typically 100kHz~1MHz) of the LLC resonant topology, improving high-frequency energy transmission efficiency, and adapting to the core requirements of small size and high power density of on-board chargers; the LLC rectifier circuit is connected in series with the LLC transformer secondary winding to synchronously match the secondary energy output rhythm, facilitating zero-voltage switching (ZVS). To reduce the turn-on and turn-off losses of the switching transistors and address the pain point of soaring switching losses under high-frequency operating conditions, the LLC lower bridge arm switching transistor is connected in series with the secondary winding of the LLC transformer. The BUCK circuit includes a BUCK converter, a BUCK rectifier circuit, and a BUCK bridge arm switching transistor group. The output terminal of the LLC transformer secondary winding is connected to the input terminal of the BUCK rectifier circuit, converting high-frequency AC energy into stable DC energy before outputting it to the BUCK circuit. This avoids high-frequency AC ripple directly entering the subsequent step-down stage, providing a stable input foundation for the BUCK circuit and reducing the difficulty of subsequent voltage regulation. The BUCK rectifier circuit is connected in series with the BUCK converter, the BUCK bridge arm switching transistor group is connected in series with the BUCK converter, and the output terminal of the BUCK converter is connected to the load.

[0029] In this embodiment, an LLC-Buck hybrid topology is adopted. The LLC circuit transmits power at high frequency, and the electromagnetic coupling of the primary and secondary windings improves the transmission efficiency. The series design of the upper and lower bridge arm switches facilitates zero-voltage switching (ZVS) and reduces switching losses under high-frequency conditions. The series configuration of the LLC and BUCK dual rectifier circuits filters high-frequency ripple and provides a stable input for the step-down stage. The BUCK circuit precisely regulates the voltage through the converter and the bridge arm switch group to ensure stable load output voltage. The overall topology module is adapted to the small size and high power density requirements of on-board chargers. It has low operating noise, strong anti-electromagnetic interference capability, and can be adapted to a wide temperature environment, effectively extending the life of the components and providing efficient, smooth and reliable power supply for on-board equipment.

[0030] A control method for an LLC-Buck hybrid topology circuit is provided, applied to an LLC-Buck hybrid topology circuit as described above. For ease of understanding, the specific flow of this embodiment is described below. Please refer to [link / reference]. Figure 1One embodiment of the LLC-Buck hybrid topology circuit control method of the present invention includes:

[0031] 101. Analyze the load output terminal of the LLC-Buck hybrid topology circuit to obtain the load power;

[0032] 102. Analyze the load power based on the preset first monitoring conditions and the preset first power threshold to obtain the feedback adjustment amount;

[0033] In this embodiment, the load power is analyzed by the first monitoring condition and the first power threshold to generate a feedback adjustment amount, which provides a precise feedback calibration basis for the LLC circuit. This allows for dynamic adaptation to power fluctuations in heavy-load vehicle scenarios, stabilizing the working state of the LLC resonant cavity, avoiding resonance mismatch and high-frequency oscillation, helping the switching transistor achieve zero-voltage turn-on (ZVS), improving the energy conversion efficiency under heavy load, and reducing switching losses. At the same time, it suppresses high-frequency noise from the transformer, resulting in stable output voltage and low ripple, enhancing the circuit's resistance to temperature drift and component aging, and laying a reliable foundation for the subsequent generation of PWM turn-on commands.

[0034] 103. Obtain the LLC operating frequency, and adjust the operating state of the LLC circuit according to the feedback adjustment amount and the LLC operating frequency to obtain the first voltage gain value;

[0035] In this embodiment, the first voltage gain value, which is the gain of the LLC secondary output voltage relative to the LLC secondary output voltage before adjustment, is equal to the input voltage gain of the BUCK circuit. It provides quantitative calibration for the LLC operating state, helps generate accurate PWM turn-on commands, thereby improving heavy-load efficiency, stabilizing resonance and suppressing noise, and ensuring reliable vehicle heavy-load power supply.

[0036] 104. Generate a PWM turn-on command based on the preset theoretical high-frequency resonance period and the first voltage gain value;

[0037] In this embodiment, by acquiring the LLC operating frequency and dynamically adjusting the LLC circuit operating state in conjunction with the feedback adjustment, and quantizing and calibrating it with the first voltage gain value, a PWM turn-on command is generated by matching the theoretical high-frequency resonant period. This can improve the energy conversion efficiency under heavy load, reduce switching losses, stabilize the operating state of the resonant cavity, reduce resonance mismatch and high-frequency oscillation, and suppress transformer noise. The output voltage is accurate and has low ripple, making it suitable for heavy-load automotive scenarios. It also enhances the circuit's resistance to temperature drift and load fluctuations, ensuring efficient and reliable energy transmission.

[0038] 105. Control the upper and lower arm switches of the LLC to turn on according to the PWM turn-on command;

[0039] In this embodiment, the conduction timing of the upper and lower bridge arm switches of LLC is precisely controlled by PWM conduction command to achieve zero-voltage switching, reduce switching losses, improve heavy-load energy conversion efficiency, stabilize the working state of LLC resonant cavity, reduce resonance mismatch and high-frequency oscillation, suppress transformer noise, adapt to heavy-load vehicle scenarios, ensure efficient energy transmission, stabilize output voltage and reduce ripple, enhance circuit robustness, and lay a reliable foundation for subsequent step-down stage.

[0040] 106. Analyze the load power according to the preset second monitoring conditions and the preset second power threshold to obtain the PWM pulse width command;

[0041] In this embodiment, the load power is analyzed by the second monitoring conditions and the second power threshold, and the PWM pulse width command is accurately generated. The light load trend can be predicted in advance, so that the BUCK circuit can respond quickly to the light load fluctuation, effectively reducing the voltage ripple and low-frequency howling caused by frequent duty cycle fluctuations. The PWM pulse width command can avoid the frequency band sensitive to human ears, reduce light load noise, adapt to the 14V battery charging needs, and provide smooth power supply for vehicle equipment.

[0042] 107. Adjust the pulse width of the BUCK bridge arm switching transistor group according to the PWM pulse width command;

[0043] In this embodiment, the BUCK bridge arm switching transistor group is precisely controlled by PWM pulse width command to perform pulse width adjustment, dynamically adapting to light load energy requirements; the duty cycle can be finely optimized to avoid the 20Hz~20kHz howling frequency band, stabilize the voltage output of LLC-Buck hybrid topology circuit and reduce ripple; it adapts to the wide temperature environment of the vehicle and light load fluctuation scenarios, improves the circuit's anti-interference capability, ensures smooth and stable power supply to vehicle equipment, and further enhances the low noise and high efficiency operation characteristics under light load conditions;

[0044] In this embodiment, under heavy load scenarios, a feedback adjustment is generated through load power analysis to dynamically optimize the LLC circuit's operating state and generate a PWM turn-on command. This precisely controls the upper and lower bridge arm switches of the LLC to achieve zero-voltage switching (ZVS), improving heavy load energy conversion efficiency and reducing switching losses. It also stabilizes the resonant cavity's operating state, avoiding resonance mismatch and high-frequency oscillations, suppressing transformer noise, resulting in accurate output voltage with low ripple, and outstanding resistance to temperature drift and component aging. Under light load scenarios, a PWM pulse width command is generated through a second monitoring condition and power threshold to control the Buck switch for pulse width adjustment, avoiding low-frequency howling bands, quickly responding to light load fluctuations, and reducing voltage ripple. This solution achieves full-condition adaptation from heavy load to light load, adapting to needs such as vehicle battery charging, exhibiting strong anti-interference capabilities, stable operation in a wide temperature range, ensuring smooth power supply to vehicle equipment, and improving the efficiency, stability, and engineering application value of hybrid topology circuits.

[0045] An extended version of this solution further includes current and voltage sensors in the LLC-Buck hybrid topology circuit; please refer to [link / reference needed]. Figure 2 In a second embodiment of the LLC-Buck hybrid topology circuit control method of the present invention, step 101 specifically includes:

[0046] 201. Control the current sensor to sample the current at the load output terminal of the LLC-Buck hybrid topology circuit according to the preset sampling frequency to obtain the load current value;

[0047] In this embodiment, the load output terminal is the final node for energy transmission. The current and voltage here directly reflect the real-time operating conditions of the actual load, unaffected by intermediate links such as LLC resonance fluctuations and Buck inductor ripple. This accurately reflects the load's power requirements, providing the most direct feedback for LLC-Buck hybrid control. The sampling frequency typically ranges from 100kHz to 1MHz, with the following selection logic: Under normal operating conditions, the sampling frequency range is generally 100kHz to 300kHz, suitable for conventional charging scenarios of on-board chargers (such as BMS constant current charging and 14V battery replenishment); Under dynamic load conditions, the sampling frequency range is generally 300kHz to 500kHz, suitable for scenarios with sudden load power changes (such as BMS). (Sudden start of fast charging, battery switching from depleted to fully charged); Under high-precision operating conditions, the sampling frequency range is generally 500kHz~1MHz, suitable for scenarios with extremely high output stability requirements (such as power supply for high-end automotive electronic devices); By sampling the voltage at the output of the LLC-Buck hybrid topology load, and using a sampling frequency of 100kHz~1MHz adapted to different scenarios (100kHz~300kHz for normal operating conditions, 300kHz~500kHz for dynamic loads, and 500kHz~1MHz for high-precision requirements), the current sensor is controlled to sample the current at the load output of the LLC-Buck hybrid topology circuit according to the sampling frequency, and a series of current signals are obtained, which are finally converted to obtain the load current value;

[0048] 202. The voltage sensor is controlled to sample the load output of the LLC-Buck hybrid topology circuit according to the sampling frequency to obtain the load voltage value.

[0049] In this embodiment, the current of the load output terminal of the LLC-Buck hybrid topology circuit is sampled by the voltage sensor according to the sampling frequency to obtain a series of voltage signals, which are finally converted to obtain the load voltage value. It can accurately capture the real load voltage, provide direct feedback for hybrid control, help the control mode to switch accurately, effectively improve the output stability and dynamic response speed, reduce noise and system loss, adapt to various vehicle charging scenarios, and has high applicability and practicality.

[0050] 203. Calculate the load power by multiplying the load current and load voltage values;

[0051] In this embodiment, by simultaneously sampling current and voltage at the load output end (the final node of energy transmission) of the LLC-Buck hybrid topology, and using a sampling frequency adapted to different scenarios, interference from intermediate links such as LLC resonance fluctuations and Buck inductor ripples is effectively avoided, accurately capturing the actual load current and voltage signals. The load power obtained by multiplying these signals provides the most direct feedback basis for LLC-Buck hybrid control.

[0052] Please see Figure 3 In a third embodiment of the LLC-Buck hybrid topology circuit control method of the present invention, step 102 specifically includes:

[0053] 301. Determine whether the load power is greater than or equal to the first power threshold;

[0054] 302. When the load power is greater than or equal to the first power threshold, a heavy load jump direction is generated;

[0055] In this embodiment, the first power threshold is the critical value of the heavy-load and light-load boundary based on the LLC-Buck topology (e.g., 10kW, which needs to be calibrated in combination with the topology's rated power and vehicle scenario requirements). By clarifying that the heavy-load condition is the prerequisite for triggering subsequent adjustments, it provides a precise trigger signal for the control modes of LLC closed-loop frequency modulation and Buck open-loop fixed maximum duty cycle, avoiding mode switching lag or erroneous switching. Different jump directions correspond to different system adaptation requirements (e.g., if the power of the hybrid circuit continues to rise, the LLC frequency modulation amplitude needs to be increased rapidly; if the power fluctuates, a smooth adjustment is needed to avoid oscillation), providing trend guidance for the feedback adjustment amount and avoiding blind adjustments.

[0056] 303. Collect the operating time of the LLC-Buck hybrid topology circuit under the load power according to the first monitoring conditions to obtain the first abnormal operating time;

[0057] In this embodiment, the first monitoring condition is: "Based on the preset monitoring duration, continuously monitor the duration of the system after the load power reaches the first power threshold (i.e., the heavy load jump condition)" to obtain the first abnormal operating time. The first abnormal operating time directly reflects the system's adaptability to heavy load jumps. The longer the time, the greater the deviation between the current LLC duty cycle, frequency, and other parameters and the heavy load requirements, and the adjustment range needs to be increased; conversely, a small adjustment is made to provide a quantitative basis for the degree of adjustment.

[0058] 304. Obtain the current LLC duty cycle and generate a feedback adjustment amount based on the heavy load jump direction, the first abnormal running time, and the current LLC duty cycle;

[0059] In this embodiment, based on the current LLC duty cycle (reflecting the real-time operating status of the system), and combined with the trend weight of the heavy load jump direction (e.g., a continuous increase weight of 1.2, a fluctuating increase weight of 0.8) and the degree coefficient of the first abnormal operating time (e.g., the coefficient increases by 0.1 for every 10ms increase in duration), a feedback adjustment amount is generated through a preset algorithm (feedback adjustment amount = baseline coefficient × trend weight × degree coefficient × (current duty cycle - optimal heavy load duty cycle)). The baseline coefficient is calibrated based on topology characteristics to ensure that the adjustment amount is within a safe range. The feedback adjustment amount is not a fixed value, but a dynamic value that integrates the trend (jump direction), degree (abnormal time), and current status (current duty cycle). This ensures both the targeting of the adjustment (fitting the power change trend) and safety (the baseline coefficient limits the adjustment range), avoiding inaccurate adjustment caused by a single parameter. The feedback adjustment amount acts on the LLC closed-loop frequency modulation link to correct the LLC duty cycle and frequency parameters, enabling the system to quickly adapt to the heavy load jump demand and improve energy transmission efficiency and stability.

[0060] In this embodiment, by accurately comparing the load power with the first power threshold (calibrated based on topology characteristics and vehicle scenario), the heavy-load condition is identified and the corresponding control mode is triggered. At the same time, the direction of the heavy-load jump is generated to provide trend guidance. Combined with the first abnormal running time collected by the first monitoring condition, the adaptation deviation is quantified. Then, the current LLC duty cycle, trend weight, degree coefficient and benchmark coefficient are linked to generate a dynamic feedback adjustment amount through a preset algorithm. This not only accurately triggers the LLC closed-loop frequency modulation and the Buck open-loop fixed maximum duty cycle mode, but also makes the adjustment both targeted and safe, reducing voltage fluctuations and frequency oscillations during heavy-load jumps, improving system stability, reducing energy loss and transformer howling. The parameters can be flexibly calibrated to adapt to various vehicle charging needs, improve the adaptability of mixed control conditions, and ensure the efficient and stable operation of the vehicle charger.

[0061] Please see Figure 4 In the fourth embodiment of the LLC-Buck hybrid topology circuit control method of the present invention, step 103 specifically includes:

[0062] 401. Adjust the LLC operating frequency according to the feedback adjustment amount to obtain the first target frequency;

[0063] In this embodiment, the calculation of the first target frequency is constrained by the resonant frequency range of the LLC topology (to avoid resonance failure caused by ultra-high or ultra-low frequencies), and dynamically corrected by the feedback adjustment. For example, when the heavy load power continues to rise, the feedback adjustment triggers the LLC operating frequency to be lowered (the lower the LLC frequency, the greater the output power), and the first target frequency is in line with the demand for high energy transmission. When the fluctuation rises, the LLC operating frequency is finely adjusted to the range of optimal resonant efficiency, balancing stability and efficiency. The first target frequency is strictly limited to the safe operating frequency range of the LLC topology to prevent the switching transistor loss from increasing sharply or the transformer from howling due to frequency exceeding the limit. This provides a clear frequency target for the LLC circuit, enabling the LLC to quickly switch from the transient state after the heavy load jump to the steady-state resonant state adapted to the heavy load.

[0064] 402. Adjust the operating state of the LLC circuit according to the first target frequency to obtain the first operating state;

[0065] In this embodiment, the operating state of the LLC circuit is determined by the resonant frequency. The first target frequency is the resonant frequency optimized based on heavy load requirements. Adjusting the operating state of the LLC circuit essentially means making the resonant cavity (inductor and capacitor) of the LLC work in the resonant mode corresponding to the target frequency. At this time, the switching loss of the LLC is the lowest and the energy transmission efficiency is the highest. This eliminates the resonant fluctuation of the LLC after heavy load jumps, establishes an efficient and stable energy transmission channel, and provides a stable operating condition basis for subsequent voltage gain evaluation.

[0066] 403. In the first operating state, obtain the secondary-side rectified output voltage of the LLC and the equivalent input voltage of the primary-side of the LLC;

[0067] In this embodiment, the LLC primary-side equivalent input voltage refers to the effective input voltage after filtering and rectification (not the original grid input voltage) on the primary side of the LLC, reflecting the actual energy supply state at the LLC input terminal and unaffected by instantaneous grid fluctuations; the LLC secondary-side rectified output voltage refers to the DC voltage after processing by the rectifier bridge on the LLC secondary side (the voltage before entering the Buck circuit), which is the direct output result of LLC energy conversion and reflects the energy transfer effect of the LLC; both voltages are sampled at the core node of LLC energy conversion without additional intermediate interference (such as the instantaneous fluctuations of the resonant cavity being suppressed by the first operating state), and the sampled data can truly reflect the input-output energy conversion relationship of the LLC; the sampling process can reuse a high-frequency sampling mechanism of 100kHz~1MHz to ensure accurate and real-time data; it provides high-quality raw data for voltage gain calculation and avoids gain evaluation deviation caused by sampling distortion;

[0068] 404. Calculate the ratio between the rectified output voltage of the LLC secondary side and the equivalent input voltage of the LLC primary side to obtain the first voltage gain value;

[0069] In this embodiment, by adjusting the feedback amount and dynamically correcting the LLC operating frequency in conjunction with the LLC topological resonant frequency range constraint, a first target frequency that safely adapts to heavy-load requirements is obtained. This avoids the surge in losses or howling caused by frequency exceeding limits, and drives the LLC to quickly enter a steady-state resonant state from a heavy-load transient state. The LLC operating state is adjusted according to this first target frequency, so that the resonant cavity operates in an optimized resonant mode, achieving low switching losses and high-efficiency energy transmission, eliminating resonance fluctuations, and establishing a stable energy transmission channel. By collecting the equivalent input voltage of the LLC primary side and the rectified output voltage of the secondary side, the first voltage gain value obtained by the ratio calculation can quantify the energy conversion effect. The overall scheme not only improves the stability and energy transmission efficiency of the LLC under heavy-load conditions, but also reduces device losses and operating noise, providing a reliable basis for subsequent optimization.

[0070] Please see Figure 5 The fifth embodiment of the LLC-Buck hybrid topology circuit control method of the present invention, step 106 specifically includes:

[0071] 501. Analyze the load power based on the second monitoring conditions and the second power threshold to obtain the feedforward adjustment amount;

[0072] In this embodiment, the load power is analyzed by using a second power threshold (light load boundary, adapted for vehicle-mounted scenario calibration) and a second monitoring condition to generate a feedforward adjustment amount. This allows for early prediction of light load trends, providing a precise adjustment basis for the BUCK circuit and reducing voltage ripple and howling caused by frequent duty cycle fluctuations. It adapts to light load requirements such as 14V battery charging, and the parameters can be flexibly calibrated. This lays the foundation for subsequent frequency optimization, improves the system's light load stability and anti-interference capability, and ensures smooth power supply to vehicle-mounted equipment.

[0073] 502. Obtain the BUCK operating frequency and adjust the BUCK operating frequency according to the feedforward adjustment amount to obtain the second target frequency;

[0074] In this embodiment, by decoding the light load trend and amplitude coefficient in the feedforward adjustment, if it is a continuous and stable light load, the adjustment direction of the BUCK operating frequency is to converge towards the center of the high-efficiency range (e.g., 150kHz); if it is a fluctuating light load, the direction is to fine-tune towards the upper limit of the high-efficiency range (e.g., 200kHz) to improve anti-interference capability. Based on the feedforward adjustment and combined with the hardware characteristics of the BUCK circuit, the BUCK operating frequency is dynamically adjusted to the second target frequency, which can accurately match the light load requirements and connect to the LLC light load mode (LLC open-loop fixed high frequency, output stable voltage to the primary side of BUCK), laying the foundation for subsequent steady-state establishment.

[0075] 503. Adjust the working state of BUCK according to the second target frequency to obtain the second working state;

[0076] In this embodiment, adjusting the BUCK operating state essentially means making the inductor and capacitor operate in the optimal filtering mode corresponding to the second target frequency. At this time, the inductor ripple is in the minimum range (e.g., ≤5%), the capacitor charging and discharging rhythm is stable, and the buck conversion efficiency of the BUCK circuit reaches its peak. In this state, the primary side of the BUCK circuit receives a stable high-frequency voltage output from the LLC circuit, and the secondary side output is smooth without additional fluctuation interference. The second target frequency has been adapted to the light load characteristics, providing an interference-free operating condition basis for subsequent voltage sampling and gain calculation, ensuring that the sampled data is true and reliable.

[0077] 504. In the second operating state, obtain the rectified output voltage of the BUCK secondary side and the equivalent input voltage of the BUCK primary side;

[0078] 505. Calculate the ratio of the rectified output voltage of the secondary side of BUCK to the equivalent input voltage of the primary side of BUCK to obtain the second voltage gain value;

[0079] In this embodiment, under the second operating state, the equivalent input voltage of the primary side of BUCK (the stable DC voltage after filtering of the LLC output, reflecting the energy supply status) and the rectified output voltage of the secondary side of BUCK are collected through a high-frequency sampling mechanism. The ratio of the two is the second voltage gain value. Ideally, this value is approximately equal to the duty cycle of BUCK. If it deviates from the ideal value, it directly reflects parameter mismatch or energy loss. High-frequency sampling ensures that the voltage data is free from ripple interference. The ratio calculation transforms the abstract voltage reduction effect into a quantifiable numerical indicator, providing a clear feedback basis for the precise optimization of subsequent PWM commands, and enabling control to move from trend prediction to precision calibration.

[0080] 506. Generate PWM pulse width command based on the preset theoretical low-frequency resonance period and the second voltage gain value;

[0081] In this embodiment, the theoretical low-frequency resonant period serves as the reference for avoiding howling (e.g., 25ms, corresponding to 40Hz, avoiding the sensitive frequency band of the human ear). Combined with the second voltage gain value, a PWM pulse width command is dynamically generated: if the second voltage gain value is close to the ideal value (e.g., 0.7, corresponding to 14V output and 20V input), the command frequency is locked at the value corresponding to the theoretical period to ensure stable voltage reduction; if the gain value is too low (e.g., 0.65, insufficient voltage reduction), the command frequency is finely adjusted to increase the duty cycle, causing the output voltage to converge towards the target value; if the gain value is too high (e.g., 0.75, excessive voltage reduction), the frequency is slightly increased to decrease the duty cycle, avoiding voltage overshoot. The PWM pulse width command directly acts on the BUCK switch driver to achieve real-time dynamic adjustment, responding to subtle fluctuations in light-load conditions (e.g., the start-stop of small automotive appliances), transforming the goals of feedforward prediction and feedback calibration into actual control actions;

[0082] In this embodiment, a feedforward adjustment amount is generated based on the second power threshold and monitoring conditions to predict the light load trend. The BUCK operating frequency is dynamically optimized accordingly. After steady-state establishment and gain quantization, a PWM pulse width command is generated to reduce ripple and howling caused by duty cycle fluctuations. The PWM pulse width command is adapted to the light load type as needed, avoiding the sensitive frequency band of the water ear and reducing light load noise. The second operating state ensures accurate voltage sampling, providing smooth power supply for scenarios such as 14V battery charging, improving the hybrid control light load closed loop, and enhancing the overall performance of the on-board charger.

[0083] Please see Figure 6 The sixth embodiment of the LLC-Buck hybrid topology circuit control method of the present invention, step 104 specifically includes:

[0084] 601. Acquire the resonant current signal of the LLC circuit according to the preset sampling period to obtain the first resonant current signal;

[0085] In this embodiment, the sampling period = 1 / sampling frequency, and the sampling period ranges from 1μs to 10μs, corresponding to a sampling frequency of 100kHz to 1MHz (100kHz corresponds to 10μs, and 1MHz corresponds to 1μs). This is a direct derived parameter of the high-frequency sampling mechanism.

[0086] 602. Perform waveform analysis on the first resonant current signal to obtain the actual high-frequency resonant period;

[0087] In this embodiment, high-frequency noise in the first resonant current signal is first filtered by Fast Fourier Transform (FFT) to extract the fundamental component of the resonant current; then, the time interval between the zero-crossing points of adjacent currents is calculated by zero-crossing detection to obtain the actual high-frequency resonant period. This method is adapted to the high-frequency characteristics of LLC, transforms the abstract waveform into quantitative parameters, and establishes a basis for comparing actual working conditions with theoretical benchmarks.

[0088] 603. Perform a deviation analysis on the theoretical high-frequency resonance period and the actual high-frequency resonance period to obtain the first deviation analysis result;

[0089] In this embodiment, the first deviation analysis result = (actual high-frequency resonance period - theoretical high-frequency resonance period) / theoretical high-frequency resonance period × 100%, where the theoretical high-frequency resonance period is preset by the LLC resonant cavity parameters (e.g., 1μs, corresponding to a 1MHz resonant frequency). A positive deviation indicates that the actual resonant frequency is too low (possibly due to inductor heating parameter drift), and a negative deviation indicates that the frequency is too high (possibly due to capacitor aging). The quantification result provides a clear direction and amplitude basis for parameter calibration.

[0090] 604. Based on the first deviation analysis results and the first voltage gain value, the preset sealing resonance parameters are calibrated to obtain the first calibration resonance parameters;

[0091] In this embodiment, the sealing resonant parameters include the resonant period reference and the sealing time parameter. Based on the first deviation analysis result, the resonant period reference in the sealing resonant parameters is corrected (e.g., adjusting the period reference to reduce the period reference and increase the resonant frequency when the positive deviation is positive). Combined with the first voltage gain value, the sealing time parameter is finely adjusted (e.g., delaying the sealing when the gain is too low and increasing the secondary output voltage). The calibrated resonant parameters are dynamic values, which can respond in real time to the resonant cavity parameter drift caused by temperature and load, and overcome the limitations of static parameters.

[0092] 605. Generate a PWM turn-on command based on the first calibration resonance parameters;

[0093] In this embodiment, the LLC resonant current signal is acquired through sampling period, and the actual high-frequency resonant period is extracted through FFT filtering and zero-crossing detection. The degree of resonance mismatch is quantified through deviation analysis, and the sealing resonant parameters are calibrated by combining the first voltage gain value (correcting the period reference and fine-tuning the sealing time). Finally, a PWM turn-on command is generated to accurately capture the high-frequency resonance characteristics of LLC, realize zero-voltage turn-on of the switching transistor, and dynamically calibrate the parameters to deal with resonance mismatch caused by temperature drift and component aging in real time. The system still operates stably under wide temperature environment; ensures stable energy supply for heavy-load fast charging; suppresses high-frequency oscillation and noise, reduces transformer noise, and meets vehicle standards; adapts to high-frequency heavy-load scenarios, has strong engineering feasibility, and improves the efficiency, stability and robustness of the on-board charger in heavy-load high-frequency operation.

[0094] Please see Figure 7 The seventh embodiment of the LLC-Buck hybrid topology circuit control method of the present invention, step 501 specifically includes:

[0095] 701. Determine whether the load power is less than or equal to the second power threshold;

[0096] 702. When the load power is less than or equal to the second power threshold, a light load jump direction is generated;

[0097] In this embodiment, the load power is compared with a second power threshold (calibrated based on the light load boundary of the LLC-Buck topology, such as 1kW, which needs to be set in conjunction with the topology's rated power, 14V battery charging, and power supply requirements for low-power vehicle equipment, etc.) to determine whether the LLC-Buck hybrid topology circuit is in a light load jump direction condition. The actual load power data is not affected by LLC resonance fluctuations or Buck inductor ripple interference, ensuring that the light load jump determination is not distorted and providing a reliable triggering premise for subsequent adjustments. The light load jump direction provides a trend guide for the feedforward adjustment amount, enabling the adjustment strategy to accurately match the light load power and reducing system fluctuations and howling caused by ineffective adjustments.

[0098] 703. The operating time of the LLC-Buck hybrid topology circuit under load power is collected according to the second monitoring conditions to obtain the second abnormal operating time;

[0099] In this embodiment, the second monitoring condition is: "continuously monitoring the duration after the load power reaches the second power threshold (i.e., the light load sudden jump condition) according to the preset monitoring duration," which is the second abnormal operating time. Under light load, the LLC is in a fixed high-frequency open-loop state, and the system stability depends on the adjustment of the Buck circuit. The second abnormal operating time directly quantifies the adaptation deviation between the Buck parameters (duty cycle, frequency) and the light load requirements. The longer the second abnormal operating time, the greater the deviation between the current Buck duty cycle and other parameters and the light load requirements (such as excessively high duty cycle leading to output voltage redundancy and inductor charging and discharging imbalance), requiring a larger adjustment range; conversely, a small adjustment is made to avoid over-adjustment causing new fluctuations. The preset monitoring duration can be flexibly set according to the light load scenario (such as 80ms for battery charging scenario and 50ms for low-power device power supply scenario) to ensure complete capture of the adaptation state; the light load adaptation degree is converted into a quantifiable time parameter, providing a clear quantitative basis for the feedforward adjustment amount and avoiding adjustment inaccuracies caused by subjective judgment.

[0100] 704. Obtain the BUCK duty cycle and generate a feedforward adjustment amount based on the light load jump direction, the second abnormal running time, and the BUCK duty cycle;

[0101] In this embodiment, based on the current Buck duty cycle (reflecting the real-time operating state of the Buck circuit), and combined with the trend weight of the light load jump direction (e.g., a continuous decrease weight of 1.1, a fluctuating decrease weight of 0.9, calibrated according to the adaptation requirements of different trends) and the degree coefficient of the second abnormal operating time (e.g., the coefficient increases by 0.08 for every 10ms increase in duration), a dynamic feedforward adjustment amount is generated through a preset algorithm (e.g., feedforward adjustment amount = baseline within the safe range (avoidance coefficient × trend weight × degree coefficient × (BUCK duty cycle - optimal duty cycle under light load)). The reference coefficient is calibrated based on the Buck topology characteristics to ensure that the feedforward adjustment is not too low (causing insufficient output voltage or too high output voltage and causing overshoot). The feedforward adjustment can adapt to the trend of light load power change in advance. At the same time, the feedforward adjustment is strictly limited to the safe operating range of the Buck circuit, taking into account both pertinence and safety. It directly acts on the Buck closed-loop pulse width modulation stage, corrects the Buck duty cycle parameter in advance, and enables the Buck circuit to quickly switch from the transient state after the light load jump to the steady state adapted to the light load, laying the foundation for subsequent voltage gain optimization and PWM pulse width modulation command generation.

[0102] In this embodiment, by accurately comparing the load power with the second power threshold (calibrated based on topology characteristics and light load scenarios), a light load jump direction is generated. Combined with the second monitoring conditions to collect the second abnormal running time, the BUCK parameter adaptation deviation is quantified. Then, the current BUCK duty cycle, trend weight, degree coefficient, and benchmark coefficient are linked to generate a dynamic feedforward adjustment amount through a preset algorithm. This accurately triggers the LLC open-loop fixed high-frequency and BUCK closed-loop pulse width modulation mode, and shortens the light load jump response time with predictive feedforward adjustment, quickly adapting to scenarios such as battery charging and low-power device start-up and shutdown. At the same time, the quantified parameters avoid subjective adjustment inaccuracies, effectively reduce BUCK duty cycle fluctuations and inductor charging and discharging imbalances, reduce light load whistling, improve output voltage stability and energy conversion efficiency, and ensure the high efficiency, low noise, and reliability of the on-board charger under light load.

[0103] Please see Figure 8 In the eighth embodiment of the LLC-Buck hybrid topology circuit control method of the present invention, step 506 specifically includes:

[0104] 801. Acquire the resonant current signal of the BUCK circuit according to the sampling period to obtain the second resonant current signal;

[0105] In this embodiment, the focus is on acquiring the resonant current signal of the BUCK circuit. This resonant current signal is a direct reflection of the resonance process of the BUCK inductor and capacitor. Especially under light load, the low-frequency component of the resonant current (20Hz~20kHz, which is sensitive to the human ear) is the core cause of howling. Sampling needs to completely capture the peak, valley and periodic characteristics of the current waveform. Under light load, the BUCK circuit is prone to low-frequency resonance due to the imbalance of inductor charging and discharging. By acquiring the second resonant current signal, the current real resonant current waveform of the BUCK circuit is reflected, laying the foundation for the calculation of the actual low-frequency resonance period.

[0106] In another embodiment, the resonant current signal is used for overcurrent protection. The core is to compare the second resonant current signal with a preset protection threshold. If the current exceeds the limit, the switch is triggered to turn off to avoid device damage. High-frequency switching noise is filtered out simultaneously when the resonant current signal is sampled to ensure the accuracy of overcurrent judgment. Protection is only triggered when the current exceeds the limit and is maintained for 1-2 sampling cycles to avoid false triggering caused by transient surges. It is suitable for automotive scenarios, can cope with device parameter drift in wide temperature environments, and balances protection reliability and circuit operation stability.

[0107] 802. Perform waveform analysis on the second resonant current signal to obtain the actual low-frequency resonant period;

[0108] In this embodiment, high-frequency ripples (such as high-frequency noise from the BUCK switch) in the second resonant current signal are first filtered out, and then the fundamental period of the low-frequency resonant component is extracted. The time interval between two adjacent current peaks (or valleys) is the actual low-frequency resonant period. Light load whistling is directly related to the low-frequency resonant period. Peak detection quickly locks the period interval. Fourier transform is used to filter interference, transforming the abstract current waveform into quantifiable period parameters, and establishing a basis for comparing actual operating conditions with theoretical benchmarks.

[0109] 803. Perform a deviation analysis on the theoretical low-frequency resonance period and the actual low-frequency resonance period to obtain the second deviation analysis result;

[0110] In this embodiment, the second deviation analysis result = (actual low-frequency resonance period - theoretical low-frequency resonance period) / theoretical low-frequency resonance period × 100%; where the theoretical low-frequency resonance period is the preset non-whistling reference low-frequency resonance period; the second deviation analysis result intuitively reflects the type and degree of resonance mismatch, providing a clear direction and amplitude basis for calibration;

[0111] 804. Based on the second deviation analysis results and the second voltage gain value, the preset start-up resonance parameters are calibrated to obtain the second calibration resonance parameters;

[0112] In this embodiment, the resonant parameters include the resonant period correlation parameter and the duty cycle correlation coefficient. Based on the second deviation analysis result, the resonant period correlation parameter is corrected (e.g., adjusting the period reference to reduce positive deviation and suppressing howling). Combined with the second voltage gain value (a quantitative indicator of BUCK voltage reduction effect), the duty cycle correlation coefficient is finely adjusted (e.g., synchronously increasing the duty cycle reference when the gain is too low to avoid insufficient voltage reduction). The calibrated second resonant parameter is a dynamic value, which can adapt to load fluctuations and temperature-induced inductor and capacitor parameter drift in real time, breaking through the adaptation limitations of static parameters and generating a dynamic resonant reference adapted to the current operating conditions, providing accurate parameter support for PWM command generation.

[0113] 805. Generate PWM pulse width command based on the preset natural frequency and the second calibration resonance parameter;

[0114] In this embodiment, the inherent frequency (determined by the inductor L and capacitor C in the hybrid circuit, such as 100kHz) is the frequency safety boundary to prevent the switching transistor from overheating due to exceeding the command frequency limit. Combined with the second calibration resonance parameter, the calibration offset coefficient is derived through an algorithm (the mainstream algorithms for deriving the calibration offset coefficient are PID control algorithm, fuzzy PID fusion algorithm, and proportional weighted fusion algorithm (all algorithms with strong engineering feasibility and real-time adaptability to automotive scenarios). When using the PID control algorithm for derivation, the difference between the second calibration resonance parameter and the ideal resonance coefficient is used as the PID deviation. The proportional stage quickly responds to the deviation, the integral stage eliminates steady-state error, and the derivative stage suppresses fluctuations. These are then superimposed to obtain the calibration offset coefficient. After constraint and smoothing by the inherent frequency safety boundary, the calibration offset coefficient is output, achieving dynamic adaptation between resonance optimization and voltage reduction accuracy). Finally, a PWM pulse width command is generated (PWM pulse width command = inherent pulse width period × calibration offset coefficient). The inherent pulse width period defines the safety range and is a fixed PWM period preset by the BUCK circuit. , The calibration is performed using the inductor and capacitor parameters of the BUCK topology, which remain unchanged during operation. The calibration offset coefficient K∈[0,1] is dynamically generated based on the deviation between the second voltage gain value and the low-frequency resonance period. It is used to quantitatively adjust the proportion of the conduction time to the inherent pulse width period, thereby achieving precise pulse width control. The PWM pulse width command is directly applied to the BUCK switching transistor drive to achieve real-time dynamic pulse width adjustment and respond to subtle changes in light load conditions. The optimization objective is transformed into actual control actions to complete light load resonance optimization and buck control.

[0115] In this embodiment, the second resonant current signal is acquired through sampling period, and the actual low-frequency resonant period is extracted through filtering and Fourier transform. The resonant mismatch is quantified by analyzing the deviation from the theoretical period. Then, the starting resonant parameters are calibrated by combining the second voltage gain value. The calibration offset coefficient is derived through PID algorithm. Finally, a PWM pulse width command is generated with the inherent frequency as the safety boundary. This can accurately capture the light-load resonant characteristics, reduce light-load noise, adapt to vehicle light-load scenarios, and achieve efficient, low-noise, and accurate step-down control with strong engineering feasibility.

[0116] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system, device, or unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0117] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0118] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An LLC-Buck hybrid topology circuit, characterized in that, include: The LLC circuit comprises an LLC circuit, a BUCK circuit, and a load; the output terminal of the LLC circuit is connected to the input terminal of the BUCK circuit, and the output terminal of the BUCK circuit is connected to the input terminal of the load; the LLC circuit includes an LLC transformer primary winding, an LLC rectifier circuit, an LLC transformer secondary winding, an LLC upper bridge arm switch, and an LLC lower bridge arm switch; the LLC upper bridge arm switch is connected in series with the LLC transformer primary winding, and the LLC transformer primary winding transfers energy to the LLC rectifier circuit through electromagnetic induction coupling; The LLC rectifier circuit is connected in series with the secondary winding of the LLC transformer, and the LLC lower bridge arm switch is connected in series with the secondary winding of the LLC transformer; the BUCK circuit includes a BUCK converter, a BUCK rectifier circuit, and a BUCK bridge arm switch group; the output terminal of the secondary winding of the LLC transformer is connected to the input terminal of the BUCK rectifier circuit, the BUCK rectifier circuit is connected in series with the BUCK converter, the BUCK bridge arm switch group is connected in series with the BUCK converter, and the output terminal of the BUCK converter is connected to the load.

2. A control method for an LLC-Buck hybrid topology circuit, characterized in that, Applied to an LLC-Buck hybrid topology circuit as described in claim 1, the LLC-Buck hybrid topology circuit control method includes: The load output terminal of the LLC-Buck hybrid topology circuit is analyzed to obtain the load power; The load power is analyzed based on the preset first monitoring conditions and the preset first power threshold to obtain the feedback adjustment amount; Obtain the LLC operating frequency, and adjust the operating state of the LLC circuit according to the feedback adjustment amount and the LLC operating frequency to obtain the first voltage gain value; A PWM turn-on command is generated based on the preset theoretical high-frequency resonance period and the first voltage gain value; The upper and lower bridge arm switches of the LLC are controlled to turn on according to the PWM turn-on command. The load power is analyzed based on the preset second monitoring conditions and the preset second power threshold to obtain the PWM pulse width command; The BUCK bridge arm switching transistor group is controlled to adjust the pulse width according to the PWM pulse width command.

3. The LLC-Buck hybrid topology circuit control method as described in claim 2, characterized in that, The LLC-Buck hybrid topology circuit also includes a current sensor and a voltage sensor. The analysis of the load output terminal of the LLC-Buck hybrid topology circuit to obtain the load power includes: The current sensor is controlled to sample the current at the load output terminal of the LLC-Buck hybrid topology circuit according to the preset sampling frequency in order to obtain the load current value. The voltage sensor is controlled to sample the load output of the LLC-Buck hybrid topology circuit according to the sampling frequency in order to obtain the load voltage value. The load power is calculated by multiplying the load current and load voltage values.

4. The LLC-Buck hybrid topology circuit control method as described in claim 2, characterized in that, The step of analyzing the load power based on preset first monitoring conditions and preset first power threshold to obtain the feedback adjustment amount includes: Determine whether the load power is greater than or equal to the first power threshold; When the load power is greater than or equal to the first power threshold, a heavy load jump direction is generated; The operating time of the LLC-Buck hybrid topology circuit under load power is collected according to the first monitoring condition to obtain the first abnormal operating time; Obtain the current LLC duty cycle and generate a feedback adjustment amount based on the heavy load jump direction, the first abnormal running time, and the current LLC duty cycle.

5. The LLC-Buck hybrid topology circuit control method as described in claim 2, characterized in that, The step of adjusting the operating state of the LLC circuit according to the feedback adjustment amount and the LLC operating frequency to obtain the first voltage gain value includes: The LLC operating frequency is adjusted according to the feedback adjustment amount to obtain the first target frequency; The operating state of the LLC circuit is adjusted according to the first target frequency to obtain the first operating state; In the first operating state, the rectified output voltage of the LLC secondary side and the equivalent input voltage of the LLC primary side are obtained; The ratio of the rectified output voltage on the secondary side of the LLC to the equivalent input voltage on the primary side of the LLC is calculated to obtain the first voltage gain value.

6. The LLC-Buck hybrid topology circuit control method as described in claim 2, characterized in that, The step of analyzing the load power based on preset second monitoring conditions and preset second power threshold to obtain PWM pulse width commands includes: The load power is analyzed based on the second monitoring conditions and the second power threshold to obtain the feedforward adjustment amount; Obtain the BUCK operating frequency and adjust it according to the feedforward adjustment amount to obtain the second target frequency; Adjust the operating state of BUCK according to the second target frequency to obtain the second operating state; In the second operating state, the rectified output voltage of the BUCK secondary side and the equivalent input voltage of the BUCK primary side are obtained; The ratio of the rectified output voltage on the secondary side of BUCK to the equivalent input voltage on the primary side of BUCK is calculated to obtain the second voltage gain value; The PWM pulse width command is generated based on the preset theoretical low-frequency resonant period and the second voltage gain value.

7. The LLC-Buck hybrid topology circuit control method as described in claim 6, characterized in that, The step of generating the PWM turn-on command based on the preset theoretical high-frequency resonant period and the first voltage gain value includes: The resonant current signal of the LLC circuit is acquired according to the preset sampling period to obtain the first resonant current signal; Waveform analysis is performed on the first resonant current signal to obtain the actual high-frequency resonant period; A deviation analysis was performed between the theoretical high-frequency resonance period and the actual high-frequency resonance period to obtain the first deviation analysis result; The preset wave-blocking resonance parameters are calibrated based on the first deviation analysis results and the first voltage gain value to obtain the first calibrated resonance parameters; A PWM turn-on command is generated based on the first calibration resonance parameters.

8. The LLC-Buck hybrid topology circuit control method as described in claim 6, characterized in that, The step of analyzing the load power based on the second monitoring conditions and the second power threshold to obtain the feedforward adjustment includes: Determine whether the load power is less than or equal to the second power threshold; When the load power is less than or equal to the second power threshold, a light load jump direction is generated; The operating time of the LLC-Buck hybrid topology circuit under load power is collected according to the second monitoring conditions to obtain the second abnormal operating time; Obtain the BUCK duty cycle and generate a feedforward adjustment amount based on the light load jump direction, the second abnormal running time, and the BUCK duty cycle.

9. The LLC-Buck hybrid topology circuit control method as described in claim 7, characterized in that, The step of generating PWM pulse width commands based on the preset theoretical low-frequency resonant period and the second voltage gain value includes: The resonant current signal of the BUCK circuit is acquired according to the sampling period to obtain the second resonant current signal; Waveform analysis of the second resonant current signal is performed to obtain the actual low-frequency resonant period; A deviation analysis was performed between the theoretical low-frequency resonance period and the actual low-frequency resonance period to obtain the second deviation analysis result; The preset start-up resonance parameters are calibrated based on the second deviation analysis results and the second voltage gain value to obtain the second calibrated resonance parameters. The PWM pulse width command is generated based on the preset natural frequency and the second calibration resonance parameter.

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