LLC resonant direct-current converter and parameter design method and control driving method thereof

Abstract

The invention discloses an LLC resonant direct-current converter and a parameter design method and a control driving method thereof, and belongs to the field of semiconductor devices. The LLC resonant direct-current converter comprises at least two first half-bridge LLC harmonic submodules, high-frequency transformers and second half-bridge LLC harmonic submodules, the high-frequency transformers and the second half-bridge LLC harmonic submodules are in one-to-one correspondence with the first half-bridge LLC harmonic submodules, and the input ends of the at least two first half-bridge LLC harmonic submodules are sequentially connected in series so as to jointly bear and distribute input direct-current total voltage; furthermore, the pressure bearing and derating of the single first half-bridge LLC harmonic sub-module are realized; the output end of each first half-bridge LLC harmonic sub-module is connected with a primary winding of a high-frequency transformer, and a secondary winding of each high-frequency transformer is connected with the input end of a second half-bridge LLC harmonic sub-module; and the output ends of the at least two second half-bridge LLC harmonic sub-modules are connected in parallel so as to share the load current and balance the output direct-current voltage of each second half-bridge LLC harmonic sub-module. According to the invention, the current conversion efficiency, the power density and the EMI performance can be improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and more specifically, to an LLC resonant DC-DC converter and its parameter design and control drive method. Background Technology

[0002] In fields such as DC power transmission and data center power systems, the performance of high step-down DC power supplies is crucial. With the rapid expansion of data center scale and the explosive growth in computing power demands, traditional power supply systems, due to issues such as high current loss and low conversion efficiency, are struggling to meet increasingly stringent power requirements. Researching high-step-down power supply solutions that directly step down the high-voltage DC bus to the desired set voltage has become a key breakthrough for the industry. This not only significantly reduces transmission current and energy loss but also adapts to the power supply requirements of next-generation GPU / TPU accelerator cards, achieving higher conversion efficiency.

[0003] However, in high buck scenarios, traditional Buck topology converters have significant drawbacks. The high buck ratio results in an extremely small duty cycle, leading to very short switching times, which drastically increases control difficulty and exacerbates switching losses and electromagnetic interference. The high-voltage side switching devices must withstand high voltage stress, and the large on-resistance of the high-voltage devices further increases losses and reduces overall efficiency. At the same time, when the load changes, its dynamic response is slow, the output voltage fluctuates greatly, and it is difficult to ensure power supply stability.

[0004] Traditional Buck topologies face several shortcomings in high buck ratio scenarios, including excessively small duty cycle, high switching losses, reduced efficiency, challenges in thermal management, high voltage component stress, electromagnetic interference (EMI) issues, and insufficient dynamic response. There is an urgent need for an LLC resonant DC-DC converter with high conversion efficiency, high power density, and excellent EMI performance. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, the present invention aims to provide an LLC resonant DC-DC converter and its parameter design and control drive method, which is beneficial for improving current conversion efficiency, power density and EMI performance.

[0006] The first aspect of this application provides an LLC resonant DC-DC converter, which includes at least two first half-bridge LLC resonant sub-modules, a high-frequency transformer corresponding to each of the first half-bridge LLC resonant sub-modules, and a second half-bridge LLC resonant sub-module, wherein: The input terminals of at least two first half-bridge LLC resonator modules are connected in series to share and distribute the total input DC voltage, thereby achieving voltage derating of a single first half-bridge LLC resonator module; The output of each first half-bridge LLC resonator module is connected to the primary winding of one of the high-frequency transformers, and the secondary winding of each of the high-frequency transformers is connected to the input of one of the second half-bridge LLC resonator modules. The output terminals of at least two second half-bridge LLC resonator modules are connected in parallel to share the load current and balance the output DC voltage of each second half-bridge LLC resonator module.

[0007] Optionally, each of the first half-bridge LLC resonator modules includes an input capacitor, two power semiconductor devices for connecting in series to form a half-bridge circuit, and a resonant cavity, wherein: The input capacitor is connected to both ends of the half-bridge circuit, and the input end of the resonant cavity is connected to the midpoint of the half-bridge circuit. The input terminal of the first half-bridge LLC resonator module includes the input capacitor and one end of the half-bridge circuit. The input capacitor and one end of the half-bridge circuit are connected to the input capacitor and the other end of the half-bridge circuit in the previous first half-bridge LLC resonator module. The output terminal of the first half-bridge LLC resonator module includes the output terminal of the resonant cavity, and the output terminal of the resonant cavity is connected to the primary winding of the high-frequency transformer.

[0008] Optionally, the resonant cavity includes a resonant inductor, a resonant capacitor, and a magnetizing inductor, wherein: The other end of the resonant inductor is connected to one end of the resonant capacitor, and the other end of the resonant capacitor is connected to one end of the magnetizing inductor. The input terminal of the resonant cavity is one end of the resonant inductor, and one end of the resonant inductor is connected to the midpoint of the half-bridge circuit. The resonant cavity includes a first output terminal and a second output terminal. The first output terminal of the resonant cavity is the other end of the resonant capacitor and one end of the magnetizing inductor. The other end of the resonant capacitor and one end of the magnetizing inductor are connected to one end of the primary winding of the high-frequency transformer. The second output terminal of the resonant cavity is the other end of the magnetizing inductor. The other end of the magnetizing inductor is connected to the other end of the primary winding of the high-frequency transformer.

[0009] Optionally, each of the high-frequency transformers includes two secondary windings, and the second half-bridge LLC resonator module includes two rectifier diodes, a filter inductor, and a filter capacitor, wherein: The cathodes of the two rectifier diodes are connected to one end of the filter inductor, and the other end of the filter inductor is connected to one end of the filter capacitor. The input terminal of the second half-bridge LLC resonator module includes the anodes of the two rectifier diodes and the other end of the filter capacitor. One end of one of the secondary windings is connected to the anode of one of the rectifier diodes, the other end of one of the secondary windings is connected to the other end of the filter capacitor and one end of the other secondary winding, and the other end of the other secondary winding is connected to the anode of the other rectifier diode. The output terminal of the second half-bridge LLC resonant module includes the two ends of the filter capacitor. One end of the filter capacitor is connected to one end of the filter capacitor in the other second half-bridge LLC resonant modules, and the other end of the filter capacitor is connected to the other end of the filter capacitor in the other second half-bridge LLC resonant modules.

[0010] A second aspect of this application provides a parameter design method for an LLC resonant DC-DC converter, applied to the LLC resonant DC-DC converter described in the first aspect, the method comprising: The turns ratio of the high-frequency transformer is determined based on the rated input voltage of the first half-bridge LLC resonator module and the rated output voltage of the second half-bridge LLC resonator module. The minimum gain is determined based on the maximum input voltage of the first half-bridge LLC resonant module, the minimum output voltage of the second half-bridge LLC resonant module, and the transformation ratio; the maximum gain is determined based on the minimum input voltage of the first half-bridge LLC resonant module, the maximum output voltage of the second half-bridge LLC resonant module, and the transformation ratio; and the equivalent AC resistance is calculated based on the transformation ratio, the output voltage of the second half-bridge LLC resonant module, and the output power. Calculate the resonant capacitance based on the equivalent AC resistance, quality factor, and resonant frequency. Calculate the resonant inductance based on the resonant capacitance and the resonant frequency; The magnetizing inductance is calculated based on the resonant inductance and the normalized inductance.

[0011] Optionally, the relationship between the gain and the normalized frequency is determined based on the normalized inductance, the number of turns of the high-frequency transformer, the resonant capacitor, the resonant inductance, and the equivalent resistance. Determine whether the normalized frequency and the gain are within the allowable range; If so, the equivalent AC resistance, the resonant capacitor, the resonant inductor, and the magnetizing inductor are determined as the parameters of the LLC resonant DC-DC converter; If not, adjust the parameters of the LLC resonant DC-DC converter and perform the step of calculating the resonant capacitance based on the equivalent AC resistance, quality factor, and resonant frequency.

[0012] A third aspect of this application provides a control and driving method for an LLC resonant DC-DC converter, characterized in that it is applied to the LLC resonant DC-DC converter described in the first aspect, wherein the power semiconductor device is a switching transistor, and the method includes: The error signal is determined based on the difference between the output voltage obtained from real-time detection and the preset reference voltage; The output control signal is calculated based on the set proportional coefficient, integral coefficient, and error signal. The frequency of the pulse width modulation signal is determined based on the reciprocal of the output control signal; A pulse width modulation signal is generated based on the frequency of the pulse width modulation signal and a preset duty cycle; The switching on and off of the switching transistor are determined based on the pulse width modulation signal to achieve the control and drive of the LLC resonant DC-DC converter.

[0013] Optionally, determining the on / off state of the switching transistor in the first half-bridge LLC resonator module based on the pulse width modulation signal includes: Determine whether to increase the turns ratio of the high-frequency transformer; If so, the same pulse width modulation signal is applied to the gates of both switching transistors to achieve the latch-up of the first half-bridge LLC resonator module.

[0014] Optionally, the method further includes: If not, complementary pulse width modulation signals are applied to the gates of the two switches to achieve alternating conduction of the two switches.

[0015] A fourth aspect of this application provides an electronic device, including: a processor and a memory; The processor is connected to a memory, wherein the memory is used to store computer programs and the processor is used to invoke the computer programs to execute the methods as described in the second or third aspect of the embodiments of this application.

[0016] The fifth aspect of this application provides a computer-readable storage medium storing a computer program, the computer program including program instructions, which, when executed by a processor, perform the methods as described in the second or third aspect of this application.

[0017] As can be seen from the embodiments of this application, the structure in which the input terminals of n first half-bridge LLC resonant modules are connected in series can distribute the total input DC voltage to each unit, breaking through the traditional single-module withstand voltage limitation and reducing the voltage stress on the switching transistors. With the voltage stress on the switching transistors reduced, each unit can use devices with low withstand voltage ratings, thereby reducing costs and improving reliability. Furthermore, voltage spike absorption components can be used to suppress voltage oscillations during the switching process, keeping the voltage stress fluctuations of the devices within a small range and extending the module's lifespan. The parallel connection of the output terminals of n second half-bridge LLC resonant modules can distribute the current flowing through the load. The current is balanced and the output DC voltage of each second half-bridge LLC resonator module is controlled. Furthermore, by combining high-frequency switching transistors and magnetic core transformers, the system power density can be significantly improved. Attached Figure Description

[0018] Figure 1 A schematic diagram of the structure of an LLC resonant DC-DC converter provided in one embodiment of this application is shown; Figure 2 A flowchart illustrating a parameter design method for an LLC resonant DC-DC converter according to an embodiment of this application is shown. Figure 3 A schematic flowchart of a control and drive method for an LLC resonant DC-DC converter according to an embodiment of this application is shown. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] Please refer to Figure 1 This document illustrates a schematic diagram of an LLC resonant DC-DC converter according to an embodiment of this application. The LLC resonant DC-DC converter includes at least two first half-bridge LLC resonant sub-modules, a high-frequency transformer corresponding to each of the first half-bridge LLC resonant sub-modules, and a second half-bridge LLC resonant sub-module, wherein: The input terminals of at least two first half-bridge LLC resonator modules are connected in series to share and distribute the total input DC voltage, thereby achieving voltage derating of a single first half-bridge LLC resonator module; The output of each first half-bridge LLC resonator module is connected to the primary winding of one of the high-frequency transformers, and the secondary winding of each of the high-frequency transformers is connected to the input of one of the second half-bridge LLC resonator modules. The output terminals of at least two second half-bridge LLC resonator modules are connected in parallel to share the load current and balance the output DC voltage of each second half-bridge LLC resonator module.

[0021] like Figure 1 As shown, the first half-bridge LLC resonant module, the high-frequency transformer corresponding to the first half-bridge LLC resonant module, and the second half-bridge LLC resonant module together constitute a unit. The LLC resonant DC-DC converter includes n units, where n is an integer greater than or equal to 2.

[0022] Furthermore, the LLC resonant DC-DC converter may also include an input voltage source and a load. The input terminals of the n first half-bridge LLC resonator modules in the n units are connected in series to share and distribute the total input DC voltage of the input voltage source. Then the voltage across each first half-bridge LLC resonator module is... This achieves the total DC voltage. The load derating. The outputs of n second half-bridge LLC resonator modules in n units are connected in parallel to the load. On both sides, to distribute the flow through the load The current is balanced and the output DC voltage of each second half-bridge LLC resonator module is controlled. The current shared by each second half-bridge LLC resonator module is .

[0023] As can be seen from the embodiments of this application, the structure in which the input terminals of n first half-bridge LLC resonant modules are connected in series can distribute the total input DC voltage to each unit, breaking through the traditional single-module withstand voltage limitation and reducing the voltage stress on the switching transistors. With the voltage stress on the switching transistors reduced, each unit can use devices with low withstand voltage ratings, thereby reducing costs and improving reliability. Furthermore, voltage spike absorption components can be used to suppress voltage oscillations during the switching process, keeping the voltage stress fluctuations of the devices within a small range and extending the module's lifespan. The parallel connection of the output terminals of n second half-bridge LLC resonant modules can distribute the current flowing through the load. The current is balanced and the output DC voltage of each second half-bridge LLC resonator module is controlled. Furthermore, by combining high-frequency switching transistors and magnetic core transformers, the system power density can be significantly improved.

[0024] Still for reference Figure 1 Each of the first half-bridge LLC resonator modules includes an input capacitor, two power semiconductor devices for connecting in series to form a half-bridge circuit, and a resonant cavity, wherein: The input capacitor is connected to both ends of the half-bridge circuit, and the input end of the resonant cavity is connected to the midpoint of the half-bridge circuit. The input terminal of the first half-bridge LLC resonator module includes the input capacitor and one end of the half-bridge circuit. The input capacitor and one end of the half-bridge circuit are connected to the input capacitor and the other end of the half-bridge circuit in the previous first half-bridge LLC resonator module. The output terminal of the first half-bridge LLC resonator module includes the output terminal of the resonant cavity, and the output terminal of the resonant cavity is connected to the primary winding of the high-frequency transformer.

[0025] Taking the first half-bridge LLC resonator module as an example, it includes an input capacitor C1, two power semiconductor devices Q1 and Q2 connected in series to form a half-bridge circuit, and a resonant cavity, wherein: The input capacitor C1 is connected to both ends of the half-bridge circuit, and the input end of the resonant cavity is connected to the midpoint of the half-bridge circuit. The input terminal of the first half-bridge LLC resonator module includes the input capacitor C1 and one end of the half-bridge circuit. The input capacitor C1 and one end of the half-bridge circuit are connected to the input capacitor and the other end of the half-bridge circuit in the previous first half-bridge LLC resonator module. Since this is the first unit, there is no previous unit, so it is directly connected to the positive terminal of the input voltage source. The output terminal of the first half-bridge LLC resonator module includes the output terminal of the resonant cavity, and the output terminal of the resonant cavity is connected to the primary winding of the high-frequency transformer Tr1.

[0026] A resonant cavity is a structure that can strongly amplify and maintain the oscillation of electromagnetic waves or sound waves at a specific frequency. It can be composed of devices such as capacitors, inductors, and resistors, and there are various ways to implement it.

[0027] Still for reference Figure 1 In one specific embodiment of this application, the resonant cavity includes a resonant inductor, a resonant capacitor, and a magnetizing inductor, wherein: The other end of the resonant inductor is connected to one end of the resonant capacitor, and the other end of the resonant capacitor is connected to one end of the magnetizing inductor. The input terminal of the resonant cavity is one end of the resonant inductor, and one end of the resonant inductor is connected to the midpoint of the half-bridge circuit. The resonant cavity includes a first output terminal and a second output terminal. The first output terminal of the resonant cavity is the other end of the resonant capacitor and one end of the magnetizing inductor. The other end of the resonant capacitor and one end of the magnetizing inductor are connected to one end of the primary winding of the high-frequency transformer. The second output terminal of the resonant cavity is the other end of the magnetizing inductor. The other end of the magnetizing inductor is connected to the other end of the primary winding of the high-frequency transformer.

[0028] Taking the first half-bridge LLC resonator module as an example, the resonant cavity includes a resonant inductor Lr1, a resonant capacitor Cr1, and a magnetizing inductor Lm1, where: The other end of the resonant inductor Lr1 is connected to one end of the resonant capacitor Cr1, and the other end of the resonant capacitor Cr1 is connected to one end of the magnetizing inductor Lm1. The input terminal of the resonant cavity is one end of the resonant inductor Lr1, and one end of the resonant inductor Lr1 is connected to the midpoint of the half-bridge circuit (Q1 and Q2). The resonant cavity includes a first output terminal and a second output terminal. The first output terminal of the resonant cavity is the other end of the resonant capacitor Cr1 and one end of the magnetizing inductor Lm1. The other end of the resonant capacitor Cr1 and one end of the magnetizing inductor Lm1 are connected to one end of the primary winding of the high-frequency transformer Tr1. The second output terminal of the resonant cavity is the other end of the magnetizing inductor Lm1. The other end of the magnetizing inductor Lm1 is connected to the other end of the primary winding of the high-frequency transformer Tr1.

[0029] In one embodiment of this application, each of the high-frequency transformers includes two secondary windings, and the second half-bridge LLC resonator module includes two rectifier diodes, a filter inductor, and a filter capacitor, wherein: The cathodes of the two rectifier diodes are connected to one end of the filter inductor, and the other end of the filter inductor is connected to one end of the filter capacitor. The input terminal of the second half-bridge LLC resonator module includes the anodes of the two rectifier diodes and the other end of the filter capacitor. One end of one of the secondary windings is connected to the anode of one of the rectifier diodes, the other end of one of the secondary windings is connected to the other end of the filter capacitor and one end of the other secondary winding, and the other end of the other secondary winding is connected to the anode of the other rectifier diode. The output terminal of the second half-bridge LLC resonant module includes the two ends of the filter capacitor. One end of the filter capacitor is connected to one end of the filter capacitor in the other second half-bridge LLC resonant modules, and the other end of the filter capacitor is connected to the other end of the filter capacitor in the other second half-bridge LLC resonant modules.

[0030] Still for reference Figure 1 Taking the first high-frequency transformer and the first second half-bridge LLC resonator module as an example, the high-frequency transformer includes upper and lower secondary windings, and the second half-bridge LLC resonator module includes two rectifier diodes D1 and D2, a filter inductor L1, and a filter capacitor Cn+1, wherein: The cathodes of the two rectifier diodes D1 and D2 are connected to one end of the filter inductor L1, and the other end of the filter inductor L1 is connected to one end of the filter capacitor Cn+1. The input of the second half-bridge LLC resonator module includes the anodes of two rectifier diodes D1 and D2 and the other end of the filter capacitor Cn+1. One end of the upper secondary winding is connected to the anode of rectifier diode D1, the other end of the upper secondary winding is connected to the other end of the filter capacitor Cn+1 and one end of the lower secondary winding, and the other end of the lower secondary winding is connected to the anode of another rectifier diode D2. The output of the second half-bridge LLC resonant module includes the two ends of the filter capacitor Cn+1. One end of the filter capacitor Cn+1 is connected to one end of the filter capacitors (Cn+2, Cn+3, ..., C2n) in the other second half-bridge LLC resonant module, and the other end of the filter capacitor Cn+1 is connected to the other end of the filter capacitors (Cn+2, Cn+3, ..., C2n) in the other second half-bridge LLC resonant module.

[0031] Please refer to Figure 2 This illustration shows a flowchart of a parameter design method for an LLC resonant DC-DC converter according to an embodiment of this application. This method can be applied to computer devices and other applications. Figure 1 In the LLC resonant DC-DC converter shown, the aforementioned computer equipment refers to electronic equipment with data calculation and processing capabilities. This method may include the following steps: Step 201: Determine the turns ratio of the high-frequency transformer based on the rated input voltage of the first half-bridge LLC resonator module and the rated output voltage of the second half-bridge LLC resonator module; For example, the formula for calculating the transformer ratio is as follows:

[0032] in, The transformation ratio is... The rated input voltage, This is the rated output voltage.

[0033] Step 202: Determine the minimum gain based on the maximum input voltage of the first half-bridge LLC resonator module, the minimum output voltage of the second half-bridge LLC resonator module, and the transformation ratio; For example, the minimum gain calculation formula is as follows:

[0034] in, For minimum gain, This is the maximum input voltage of the first half-bridge LLC resonator module. This is the minimum output voltage of the second half-bridge LLC resonator module.

[0035] Step 203: Determine the maximum gain based on the minimum input voltage of the first half-bridge LLC resonator module, the maximum output voltage of the second half-bridge LLC resonator module, and the transformation ratio; For example, the formula for calculating the maximum gain is as follows:

[0036] in, For minimum gain, This is the maximum input voltage of the first half-bridge LLC resonator module. This is the minimum output voltage of the second half-bridge LLC resonator module.

[0037] Step 204: Calculate the equivalent AC resistance based on the transformer ratio, the output voltage and output power of the second half-bridge LLC resonator module; For example, the formula for calculating equivalent AC resistance is as follows:

[0038] in, This is the equivalent AC resistance. , This refers to the output voltage and output power of the second half-bridge LLC resonator module.

[0039] Step 205: Calculate the resonant capacitance based on the equivalent AC resistance, quality factor, and resonant frequency; For example, the formula for calculating the resonant capacitance is as follows:

[0040] in, The resonant frequency, For quality factors, The relationship between the achievable peak gain and the quality factor can be determined by different normalized inductances. This relationship can be in the form of a function, a table, or a graph, and the specific form of presentation is not limited.

[0041] Step 206: Calculate the resonant inductance based on the resonant capacitance and the resonant frequency; For example, the formula for calculating resonant inductance is as follows:

[0042] in, It is a resonant inductor.

[0043] Step 207: Calculate the magnetizing inductance based on the resonant inductance and the normalized inductance.

[0044] For example, the formula for calculating the magnetizing inductance is as follows:

[0045] in, For magnetizing inductance, This is a normalized inductance.

[0046] It should be noted that steps 202 to 204 can be executed simultaneously or at different times, and there is no strict order of dependency.

[0047] Figure 2 The example provides a parameter design method for an LLC resonant DC-DC converter. According to this example, each parameter can be determined step by step and quickly. However, the accuracy of the above parameters still needs to be further verified. Please refer to the following example.

[0048] Furthermore, the method also includes: The relationship between the gain and the normalized frequency is determined based on the normalized inductance, the number of turns of the high-frequency transformer, the resonant capacitor, the resonant inductance, and the equivalent resistance. Determine whether the normalized frequency and the gain are within the allowable range; If so, the equivalent AC resistance, the resonant capacitor, the resonant inductor, and the magnetizing inductor are determined as the parameters of the LLC resonant DC-DC converter; If not, adjust the parameters of the LLC resonant DC-DC converter and perform the step of calculating the resonant capacitance based on the equivalent AC resistance, quality factor, and resonant frequency.

[0049] For example, the relationship between gain and normalized frequency can be determined according to the following formula:

[0050] in, For gain, The number of turns of the high-frequency transformer. For the normalized frequency, the relationship between gain and normalized frequency can be in the form of a function, a table, or a graph; the specific form of presentation is not limited.

[0051] To determine whether the normalized frequency and the gain are within acceptable ranges, their respective maximum and minimum values ​​can be measured and compared with the calculated maximum and minimum values ​​from the previous steps. If they are not within acceptable ranges, the normalized frequency and quality factor can be changed and recalculated.

[0052] Please refer to Figure 3 This illustration shows a flowchart of a control and drive method for an LLC resonant DC-DC converter according to an embodiment of this application. This method can be applied to computer devices and other applications. Figure 1 In the LLC resonant DC-DC converter shown, the power semiconductor device is a switching transistor, and the aforementioned computer equipment refers to an electronic device with data computing and processing capabilities. This method may include the following steps: Step 301: Determine the error signal based on the difference between the output voltage obtained from real-time detection and the preset reference voltage; Step 302: Calculate the output control signal based on the set proportional coefficient, integral coefficient, and error signal; Step 303: Determine the frequency of the pulse width modulation signal based on the reciprocal of the output control signal; Step 304: Generate a pulse width modulation signal based on the frequency of the pulse width modulation signal and the preset duty cycle; Step 305: Determine the on and off states of the switching transistor based on the pulse width modulation signal to achieve control and drive of the LLC resonant DC-DC converter.

[0053] Specifically, determining the on / off state of the switching transistor in the first half-bridge LLC resonator module based on the pulse width modulation signal includes: Determine whether to increase the turns ratio of the high-frequency transformer; If so, the same pulse width modulation signal is applied to the gates of both switching transistors to achieve the latch-up of the first half-bridge LLC resonator module.

[0054] Furthermore, the method also includes: If not, complementary pulse width modulation signals are applied to the gates of the two switches to achieve alternating conduction of the two switches.

[0055] The frequency of the pulse width modulation (PWM) signal is determined based on the reciprocal of the output control signal; that is, the reciprocal of the output control signal is used as the frequency of the PWM signal. A preset duty cycle, for example, can be 0.5. When it is necessary to increase the transformation ratio of the high-frequency transformer, the PWM signal and its inverse signal are applied to the gates of two switching transistors, respectively. For example, Q1 is the master switch and Q2 is the slave switch. The PWM signal is applied to the gate of Q1, and the inverse PWM signal is applied to the gate of Q2, thereby controlling the switching transistors to turn on and off, thus adjusting the output voltage and ultimately stabilizing it at the target value. When setting the PI parameters, the integral coefficient Ki can be initially set to 0, and the proportional coefficient Kp can be gradually increased until the output voltage waveform exhibits constant amplitude oscillation. Then, the integral coefficient Ki can be gradually increased until the output voltage stabilizes.

[0056] In addition, this embodiment includes n units. When it is necessary to reduce the transformation ratio of the high-frequency transformer, the number of units that need to be locked can be determined according to the specific reduction amount. Then, by applying the same pulse width modulation signal to the gates of the two switching transistors of the unit, the first half-bridge LLC resonator module in the unit is locked, so that the unit does not participate in voltage transformation. Therefore, this embodiment can flexibly control the conduction state of specific units according to requirements, thereby achieving gain range adjustment.

[0057] In summary, the control and driving method provided in this application is very simple and easy to operate. By controlling the gate level of the switching transistor, partial unit latch-up is achieved to adjust the turns ratio, and the gain is adjusted by pulse frequency modulation. Using closed-loop PI control, the output voltage is compared with the reference value, and the driving frequency of the half-bridge module is adjusted through PI calculation to stabilize the output. At the same time, power semiconductor switching transistors are used to reduce high-frequency switching losses and improve power density. The half-bridge LLC submodule is designed with key parameters according to a specific process to ensure performance compatibility under different turns ratios.

[0058] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a computer, causes the computer to perform the functions of the computer system of the parameter design method or the control and drive method of the LLC resonant DC converter in any of the above embodiments.

[0059] This application also provides a computer program product containing instructions that, when executed by a computer, cause the computer to perform the functions of the computer system of the parameter design method or the control and drive method of the LLC resonant DC converter in any of the above embodiments.

[0060] It is understood that the specific examples in this application are only intended to help those skilled in the art better understand the implementation methods of this application, and are not intended to limit the scope of the invention.

[0061] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not limit the implementation process of the embodiments of this application in any way.

[0062] It is understood that the various implementation methods described in this application can be implemented individually or in combination, and the implementation methods in this application are not limited in this respect.

[0063] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0064] It is understood that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by the integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0065] It is understood that the memory in the embodiments of this application may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Specifically, non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may be random access memory (RAM). It should be noted that the memory in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0066] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0067] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the aforementioned method implementations, and will not be repeated here.

[0068] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0069] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0070] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0071] If a function 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 this application, in essence, or the part that contributes to the prior art, or part of the technical solution, can be embodied in the form of a software product. The 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 of various embodiments of this application. 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.

[0072] The above are merely specific embodiments of this application, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. An LLC resonant DC-DC converter, characterized in that, The LLC resonant DC-DC converter includes at least two first half-bridge LLC resonant sub-modules, a high-frequency transformer corresponding to each of the first half-bridge LLC resonant sub-modules, and a second half-bridge LLC resonant sub-module, wherein: The input terminals of at least two first half-bridge LLC resonator modules are connected in series to share and distribute the total input DC voltage, thereby achieving voltage derating of a single first half-bridge LLC resonator module; The output of each first half-bridge LLC resonator module is connected to the primary winding of one of the high-frequency transformers, and the secondary winding of each of the high-frequency transformers is connected to the input of one of the second half-bridge LLC resonator modules. The output terminals of at least two second half-bridge LLC resonator modules are connected in parallel to share the load current and balance the output DC voltage of each second half-bridge LLC resonator module.

2. The LLC resonant DC-DC converter according to claim 1, characterized in that, Each of the first half-bridge LLC resonant submodules includes an input capacitor, two power semiconductor devices for connecting in series to form a half-bridge circuit, and a resonant cavity, wherein: The input capacitor is connected to both ends of the half-bridge circuit, and the input end of the resonant cavity is connected to the midpoint of the half-bridge circuit. The input terminal of the first half-bridge LLC resonator module includes the input capacitor and one end of the half-bridge circuit. The input capacitor and one end of the half-bridge circuit are connected to the input capacitor and the other end of the half-bridge circuit in the previous first half-bridge LLC resonator module. The output terminal of the first half-bridge LLC resonator module includes the output terminal of the resonant cavity, and the output terminal of the resonant cavity is connected to the primary winding of the high-frequency transformer.

3. The LLC resonant DC-DC converter according to claim 2, characterized in that, The resonant cavity includes a resonant inductor, a resonant capacitor, and a magnetizing inductor, wherein: The other end of the resonant inductor is connected to one end of the resonant capacitor, and the other end of the resonant capacitor is connected to one end of the magnetizing inductor. The input terminal of the resonant cavity is one end of the resonant inductor, and one end of the resonant inductor is connected to the midpoint of the half-bridge circuit. The resonant cavity includes a first output terminal and a second output terminal. The first output terminal of the resonant cavity is the other end of the resonant capacitor and one end of the magnetizing inductor. The other end of the resonant capacitor and one end of the magnetizing inductor are connected to one end of the primary winding of the high-frequency transformer. The second output terminal of the resonant cavity is the other end of the magnetizing inductor. The other end of the magnetizing inductor is connected to the other end of the primary winding of the high-frequency transformer.

4. The LLC resonant DC-DC converter according to claim 1, characterized in that, Each of the high-frequency transformers includes two secondary windings, and the second half-bridge LLC resonator module includes two rectifier diodes, a filter inductor, and a filter capacitor, wherein: The cathodes of the two rectifier diodes are connected to one end of the filter inductor, and the other end of the filter inductor is connected to one end of the filter capacitor; The input terminal of the second half-bridge LLC resonator module includes the anodes of the two rectifier diodes and the other end of the filter capacitor. One end of one of the secondary windings is connected to the anode of one of the rectifier diodes, the other end of one of the secondary windings is connected to the other end of the filter capacitor and one end of the other secondary winding, and the other end of the other secondary winding is connected to the anode of the other rectifier diode. The output terminal of the second half-bridge LLC resonant module includes the two ends of the filter capacitor. One end of the filter capacitor is connected to one end of the filter capacitor in the other second half-bridge LLC resonant modules, and the other end of the filter capacitor is connected to the other end of the filter capacitor in the other second half-bridge LLC resonant modules.

5. A parameter design method for an LLC resonant DC-DC converter, characterized in that, Applied to the LLC resonant DC-DC converter of claim 4, the method includes: The turns ratio of the high-frequency transformer is determined based on the rated input voltage of the first half-bridge LLC resonator module and the rated output voltage of the second half-bridge LLC resonator module. The minimum gain is determined based on the maximum input voltage of the first half-bridge LLC resonant module, the minimum output voltage of the second half-bridge LLC resonant module, and the transformation ratio; the maximum gain is determined based on the minimum input voltage of the first half-bridge LLC resonant module, the maximum output voltage of the second half-bridge LLC resonant module, and the transformation ratio; and the equivalent AC resistance is calculated based on the transformation ratio, the output voltage of the second half-bridge LLC resonant module, and the output power. Calculate the resonant capacitance based on the equivalent AC resistance, quality factor, and resonant frequency. Calculate the resonant inductance based on the resonant capacitance and the resonant frequency; The magnetizing inductance is calculated based on the resonant inductance and the normalized inductance.

6. The method according to claim 5, characterized in that, The method further includes: The relationship between the gain and the normalized frequency is determined based on the normalized inductance, the number of turns of the high-frequency transformer, the resonant capacitor, the resonant inductance, and the equivalent resistance. Determine whether the normalized frequency and the gain are within the allowable range; If so, the equivalent AC resistance, the resonant capacitor, the resonant inductor, and the magnetizing inductor are determined as the parameters of the LLC resonant DC-DC converter; If not, adjust the parameters of the LLC resonant DC-DC converter and perform the step of calculating the resonant capacitance based on the equivalent AC resistance, quality factor, and resonant frequency.

7. A control and drive method for an LLC resonant DC-DC converter, characterized in that, Applied to the LLC resonant DC-DC converter according to any one of claims 2-4, wherein the power semiconductor device is a switching transistor, the method comprises: The error signal is determined based on the difference between the output voltage obtained from real-time detection and the preset reference voltage; The output control signal is calculated based on the set proportional coefficient, integral coefficient, and error signal. The frequency of the pulse width modulation signal is determined based on the reciprocal of the output control signal; A pulse width modulation signal is generated based on the frequency of the pulse width modulation signal and a preset duty cycle; The switching on and off of the switching transistor are determined based on the pulse width modulation signal to achieve the control and drive of the LLC resonant DC-DC converter.

8. The method according to claim 7, characterized in that, The step of determining the on / off state of the switching transistor in the first half-bridge LLC resonator module based on the pulse width modulation signal includes: Determine whether to increase the turns ratio of the high-frequency transformer; If so, the same pulse width modulation signal is applied to the gates of both switching transistors to achieve the latch-up of the first half-bridge LLC resonator module.

9. The method according to claim 8, characterized in that, The method further includes: If not, complementary pulse width modulation signals are applied to the gates of the two switches to achieve alternating conduction of the two switches.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, the computer program including program instructions that, when executed by a processor, perform the method as described in any one of claims 5-6 or 7-9.

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