A multi-mode control based ultra-wide gain LLC resonant converter topology

Abstract

This invention discloses an ultra-wide gain LLC resonant converter topology based on multi-mode control. By combining four operating modes—primary-side series half-bridge, half-bridge, dual half-bridge, and full-bridge half-bridge—with two rectifier modes—secondary-side full-bridge rectification and voltage doubler rectification—six progressively increasing gain operating modes are formed. This enables the converter to achieve a stable 24V output within a twelve-fold ultra-wide input voltage range of 40V to 480V. Each mode only requires frequency conversion within a narrow frequency range of 120kHz to 180kHz, significantly simplifying the design of magnetic components and avoiding electromagnetic compatibility and loop stability issues associated with wide-frequency regulation. All operating modes achieve zero-voltage turn-on of the primary and secondary-side switches and zero-current turn-off of the secondary-side rectifiers, exhibiting excellent soft-switching characteristics, low cycle energy, and high conversion efficiency. The six modes share the same topology architecture; switching only requires changing the drive logic, without the need for additional components. This results in high topology reusability, simple control, and strong reliability.

Description

Technical Field

[0001] This invention relates to the field of power electronic conversion technology, and more specifically to an ultra-wide gain LLC resonant converter topology based on multi-mode control. Background Technology

[0002] In industrial applications of power electronic conversion technology, an increasing number of scenarios require DC / DC converters to operate efficiently and stably over input voltage ranges that are tens or even wider. In photovoltaic power generation systems, the voltage of a single string of modules can fluctuate from as low as 20V to over 60V depending on sunlight and temperature. If direct adaptation to arrays with different series and parallel configurations is considered, the input voltage range can be more than tenfold. In the electric vehicle sector, on-board chargers need to be compatible with different global power grids (single-phase 100V to three-phase 480V) and power battery packs with different voltage platforms (from 400V to 800V), often covering an input voltage range of 40V to 480V or even wider. In industrial control systems, factory automation equipment generally uses 24V DC power, while the upstream bus voltage may come from a high-voltage DC microgrid (380V). For applications requiring low-voltage backup battery packs (48V or -480V), converters need ultra-wide input range capabilities to achieve a unified power supply solution. In communication base stations and data centers, the terminal voltage of backup battery packs can vary by several times between deep discharge and constant-voltage charging. Coupled with the continuous drop in DC bus voltage during power outages, converters face an effective input range requirement of more than 10 times. Furthermore, during fuel cell startup, the output voltage gradually rises from near zero volts to the rated value. In hydrogen production power supplies, the electrolyzer voltage varies significantly with current density. Ultra-wide input converters can directly eliminate the need for a pre-regulatory circuit, greatly improving system efficiency. Therefore, researching isolated DC / DC converters that can operate efficiently and reliably over an ultra-wide input voltage range has significant engineering application value.

[0003] Among various isolated DC / DC converter topologies, LLC resonant converters have attracted considerable attention due to their outstanding soft-switching characteristics. Their primary-side switches can achieve zero-voltage turn-on across the entire load range, and their secondary-side rectifier diodes can achieve zero-current turn-off when the switching frequency is below the resonant frequency. This effectively reduces switching losses and diode reverse recovery losses, making the converter easier to achieve high frequency and high power density. However, traditional LLC resonant converters typically employ pulse frequency modulation strategies to regulate the output voltage. When applied to applications with ultra-wide input voltage ranges, this modulation strategy faces a series of insurmountable bottlenecks: Under low input voltage and high gain requirements, the switching frequency must drop significantly below the resonant frequency, leading to a significant increase in excitation current and circulating energy within the resonant cavity, a sharp rise in primary-side conduction losses, and if the frequency is too low, the converter may enter the capacitive operating region, causing the primary-side switch to lose its zero-voltage turn-on capability, seriously threatening the safe and reliable operation of the system; Under high input voltage and low gain requirements, especially under light load or no-load conditions, the switching frequency needs to rise sharply to a higher frequency range. At this time, the secondary-side rectifier diode will lose its zero-current turn-off characteristic, and the reverse recovery loss will increase dramatically. At the same time, the excessively high switching frequency leads to a significant increase in the turn-off loss and drive loss of the switch, resulting in a significant decrease in overall efficiency. In addition, the excessively wide switching frequency range also poses severe challenges to the optimized design of magnetic components, the design of electromagnetic compatibility filters, and the stability of the control loop. Therefore, traditional frequency-controlled LLC resonant converters struggle to adapt to the application requirements of ultra-wide input voltage ranges while maintaining efficient soft switching.

[0004] A conventional half-bridge LLC resonant converter (Research on Half-Bridge LLC Resonant DC-DC Converter, Zhao Pengcheng, North China University of Technology) employs a fixed topology and a single-pulse frequency modulation strategy. It adjusts the voltage gain by drastically changing the switching frequency to adapt to input voltage and load variations. This scheme can achieve soft switching near the resonant point, but over an ultra-wide input voltage range, a significant frequency reduction is required to obtain high gain, leading to a surge in magnetizing current and circulating energy, increased conduction losses, and even loss of zero-voltage turn-on. Conversely, a significant frequency increase is needed to obtain low gain, causing the secondary diodes to lose zero-current turn-off, and a sharp increase in reverse recovery losses and switching losses. Furthermore, the excessively wide frequency range poses challenges to magnetic component design, electromagnetic compatibility, and loop stability. Summary of the Invention

[0005] The purpose of this invention is to overcome the technical defects existing in the background technology and provide an ultra-wide gain LLC resonant converter topology based on multi-mode control. By combining multiple operating modes on the primary side and rectifier modes on the secondary side, six gain-progressive operating modes are formed. This allows the converter to perform frequency conversion in a narrow frequency range for each mode within a twelve-fold ultra-wide input voltage range, thereby maintaining soft switching and high efficiency under all operating conditions. It simplifies the design of magnetic components and control, enabling high-efficiency conversion over an ultra-wide input voltage range and a full load range, maintaining soft switching under all operating conditions, and providing simple control, a narrow switching frequency range, and higher efficiency.

[0006] The present invention is achieved by at least one of the following technical solutions.

[0007] An ultra-wide gain LLC resonant converter topology based on multi-mode control includes a primary-side switching network, a resonant network, a transformer, a secondary-side variable voltage multiplier rectifier structure, and an output filter capacitor. With output load ; The primary-side switching network includes four primary-side power switches ( , , , and input voltage Among them, the first primary-side power switch transistor The source and the second primary power switch The drains of the transistors are connected to form the left bridge arm, and the third primary power switch transistor is connected to the drain of the transistor. The source and the fourth primary power switch The drains of the two terminals are connected to form the right bridge arm, and the input voltage is... The positive terminal is connected to the first primary power switch transistor. The drain and the third primary power switch The drain and negative terminal are connected to the second primary-side power switch transistor. The source and the fourth primary power switch The source pole; The resonant network includes two resonant inductors ( , ), two resonant capacitors ( , ) and two magnetizing inductors ( , ), by the first resonant inductor First resonant capacitor First excitation inductor The first resonant cavity is formed by connecting them in series, and the second resonant inductor is connected in series. Second resonant capacitor Second excitation inductor The second resonant cavity is formed by connecting them in series, and the first resonant inductor is connected in series. Second resonant inductor Connected to the first left bridge arm respectively; the first magnetizing inductor Second excitation inductor They are respectively connected to the first right bridge arm; The transformer includes a first high-frequency transformer. Second high-frequency transformer First high-frequency transformer Second high-frequency transformer Respectively with the second resonant inductor Second excitation inductor in parallel; The secondary-side variable voltage multiplier rectifier structure includes multiple diodes ( , , , , Secondary power switching transistor And two voltage multiplier capacitors ( , ); First diode The positive terminal and the second diode The negative terminals are connected to form the second left bridge arm, and the third diode... The positive electrode and the fourth diode The negative terminals are connected to form the middle bridge arm, the fifth diode. The positive and secondary power switching transistors The drains are connected to form the second right bridge arm.

[0008] Furthermore, the first resonant inductor With the first resonant capacitor Series connection, first resonant inductor Connect the first left bridge arm and the first resonant capacitor. Connect the first high-frequency transformer The primary side of the same name terminal, the first high-frequency transformer The primary side of the non-standard terminal is connected to the first right bridge arm, the first magnetizing inductor. Parallel connection to the first high-frequency transformer The original edge.

[0009] Furthermore, the second resonant inductor With the second resonant capacitor Series connection, second resonant inductor The second resonant capacitor is connected to the first left bridge arm and to the high-frequency transformer. The primary side of the same name terminal, the second high-frequency transformer The primary-side non-nominal terminal is then connected to the third primary-side power switch. Fourth primary power switch transistor The source of the second magnetizing inductor Parallel connection to the second high-frequency transformer The original edge.

[0010] Furthermore, the first voltage multiplier capacitor One end is connected to a high-frequency transformer The second-side terminal is connected to the same name, and the other end is connected to the second left bridge arm; the first high-frequency transformer The secondary side of the transformer with different names and the second high-frequency transformer The secondary side terminals of the two capacitors are connected together and then connected to the middle bridge arm; the second voltage multiplier capacitor... One end is connected to a high-frequency transformer One end is the secondary side, and the other end is connected to the second right bridge arm.

[0011] Furthermore, the first high-frequency transformer Second high-frequency transformer The ratios are respectively , The transformer ratio parameters are consistent.

[0012] Furthermore, by controlling the on / off state of the primary-side power switch, the primary side can operate in series half-bridge, half-bridge, double half-bridge, and full-bridge half-bridge modes.

[0013] Furthermore, the secondary power switch is controlled by two voltage multiplier capacitors. The conduction and turn-off states enable the secondary side to operate in two modes: full-bridge rectification and voltage multiplier rectification. Gain broadening is achieved through the following six modes: series half-bridge-full-bridge rectification, half-bridge-full-bridge rectification, dual half-bridge-full-bridge rectification, full-bridge half-bridge-full-bridge rectification, dual half-bridge-voltage multiplier rectification, and full-bridge half-bridge-voltage multiplier rectification.

[0014] Furthermore, let the gain of the resonant converter be M, where M is the output voltage. Multiply by the transformer primary-secondary turns ratio and then by the input voltage. The ratio; When 0.25 ≤ M < 0.4, the converter operates in series half-bridge-full-bridge rectification mode, at which time the first primary-side power switch transistor... Second primary-side power switch Maintain constant off state, third primary-side power switch Fourth primary power switch transistor The secondary power switch S5 is controlled by synchronous rectification due to the complementary conduction and the existence of a dead zone. When 0.4 ≤ M < 0.8, the converter operates in half-bridge-full-bridge rectification mode, at which time the third primary-side power switch transistor... Fourth primary power switch transistor Maintain constant off state, first primary-side power switch Second primary-side power switch Complementary conduction, but with a dead time, secondary power switch transistor Synchronous rectification control is adopted; When 0.8 ≤ M < 1.2, the converter operates in the dual half-bridge to full-bridge rectification mode, at which time the third primary-side power switch transistor... Maintain constant off, fourth primary-side power switch Maintain constant conduction, the first primary-side power switch Second primary-side power switch Complementary conduction, but with a dead time, secondary power switch transistor Synchronous rectification control is adopted; When 1.2 ≤ M < 1.8, the converter operates in full-bridge / half-bridge / full-bridge rectification mode. At this time, the first primary-side power switch... Fourth primary power switch transistor The signals are the same, the second primary-side power switch Third primary power switch transistor The signals are the same, the first primary-side power switch Fourth primary power switch transistor With the second primary-side power switch Third primary power switch transistor Complementary conduction, but with a dead time, secondary power switch transistor Synchronous rectification control is adopted; When 1.8 ≤ M < 2, the converter operates in dual half-bridge voltage doubler rectifier mode, at which time the third primary-side power switch transistor... Maintain constant off, fourth primary-side power switch Maintain constant conduction, the first primary-side power switch Second primary-side power switch Complementary conduction, but with a dead time, secondary power switch transistor Maintain constant conduction to achieve voltage multiplier rectification; When 2≤M≤3, the converter operates in full-bridge / half-bridge voltage doubler rectifier mode, at which time the first primary-side power switch transistor... Fourth primary power switch transistor The signals are the same, the second primary-side power switch Third primary power switch transistor The signals are the same, the first primary-side power switch Fourth primary power switch transistor With the second primary-side power switch Third primary power switch transistor Complementary conduction, but with a dead time, secondary power switch transistor Maintain constant conduction to achieve voltage multiplier rectification.

[0015] Furthermore, in each mode, gain control under a single mode is achieved by controlling the frequency of the primary-side power switch, i.e., pulse frequency modulation. The gain switching of the six operating modes is achieved by sampling the input voltage and determining the voltage threshold range into which the input voltage falls to match the corresponding power switch drive.

[0016] Furthermore, the voltage threshold range corresponds to the gain M, where M is the output voltage. Multiply by the transformer primary-secondary turns ratio and then by the input voltage. The ratio of the turns ratio remains constant, while the change in input voltage corresponds to a change in gain M.

[0017] The present invention adopts the above technical solution and has the following advantages: (1) This invention combines four primary-side operating modes with two secondary-side rectification modes to form six gain-progressive operating modes, enabling the converter to achieve a stable 24V output within a 12-fold input voltage range from 40V to 480V. Each mode only requires pulse frequency modulation within a narrow frequency range of 120kHz to 180kHz. The narrow frequency range greatly simplifies the optimization design of magnetic components such as transformers and resonant inductors, allowing core selection and winding design to be performed around the resonant frequency point. At the same time, it avoids the difficulties in electromagnetic compatibility filtering design and the problem of drastic changes in control loop characteristics caused by wide-frequency regulation, significantly improving the feasibility of system engineering.

[0018] (2) This invention maintains soft-switching characteristics in all operating modes, effectively reducing switching losses and reverse recovery losses. The narrow gain range allows for a larger excitation inductance value, reducing the peak excitation current and intracavity circulating energy, and decreasing conduction losses. The secondary-side switch uses synchronous rectification to reduce the on-state voltage drop in full-bridge rectification mode and constant conduction to simplify control in voltage doubler rectification mode, balancing efficiency optimization and engineering simplicity.

[0019] (3) All six modes of this invention are based on the same topology architecture. Switching only requires changing the driving logic, without the need for additional devices or hardware modifications, resulting in a high degree of topology reuse. The primary-side resonant slot operates symmetrically, eliminating the risk of transformer magnetization. The secondary-side switching transistor smoothly transitions between synchronous rectification and constant conduction. Mode switching is naturally determined based on the input voltage. The overall scheme has a clear structure, is easy to implement, and has high reliability. Attached Figure Description

[0020] Figure 1 Here is a topology diagram of an ultrawide gain LLC resonant converter based on multimode control, as shown in the embodiment. Figure 2This is a topology diagram of the ultra-wide gain LLC resonant converter with multi-mode control in the series half-bridge to full-bridge rectifier mode. Figure 3 The equivalent topology of the ultrawide gain LLC resonant converter with multimode control in the series half-bridge to full-bridge rectifier mode is shown in the example. Figure 4 Key waveforms of an ultrawide gain LLC resonant converter with multimode control in series half-bridge to full-bridge rectifier mode are shown in the example. Figure 5 The equivalent circuit diagram of the four operating stages of the multi-mode controlled ultra-wide gain LLC resonant converter in the series half-bridge-full-bridge rectification mode is shown in the example. Figure 6 The topology diagram of the ultra-wide gain LLC resonant converter with multi-mode control in the half-bridge-full-bridge rectifier mode is shown in the example. Figure 7 The topology diagram of the ultrawide gain LLC resonant converter with multimode control in the dual half-bridge to full-bridge rectifier mode is shown in the example. Figure 8 The topology diagram of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge half-bridge-full-bridge rectifier mode is shown in the example. Figure 9 The topology diagram of the ultrawide gain LLC resonant converter with multimode control in the dual half-bridge voltage doubler rectifier mode is shown in the example. Figure 10 The topology diagram of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge half-bridge voltage doubler rectifier mode is shown in the example. Figure 11 Key waveforms of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge, half-bridge, voltage doubler rectifier mode are shown in the example. Figure 12(a) shows the operating stages of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge, half-bridge, voltage doubler rectifier mode of the embodiment. - Equivalent circuit diagram; Figure 12(b) shows the operating stages of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge, half-bridge, voltage doubler rectifier mode of the embodiment. - Equivalent circuit diagram; Figure 12(c) shows the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge, half-bridge, voltage doubler rectifier mode of the embodiment. - Equivalent circuit diagram; Figure 12(d) shows the operating stage d of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge, half-bridge, voltage doubler rectifier mode of the embodiment. - Equivalent circuit diagram; Figure 12(e) shows the operating stages of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge, half-bridge, voltage doubler rectifier mode of the embodiment. - Equivalent circuit diagram; Figure 12(f) shows the operating stage of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge, half-bridge, and voltage doubler rectifier modes of the embodiment. - Equivalent circuit diagram; Figure 12(g) shows the operating stages of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge, half-bridge, and voltage doubler rectifier modes in the embodiment. - Equivalent circuit diagram; Figure 12(h) shows the operating stages of the ultra-wide gain LLC resonant converter with multi-mode control in the full-bridge, half-bridge, and voltage doubler rectifier modes in the embodiment. - Equivalent circuit diagram; Figure 13 The simulation waveforms of key parameters of the ultra-wide gain LLC resonant converter with multi-mode control in the example are shown in the series half-bridge-full-bridge rectification mode and the full-bridge half-bridge-voltage doubler rectification mode. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0022] like Figure 1 As shown in this embodiment, an ultra-wide gain LLC resonant converter topology based on multi-mode control is presented. The converter includes a primary-side switching network, a resonant network, a transformer, a secondary-side variable voltage multiplier rectifier structure, and an output filter capacitor. With output load .

[0023] The primary-side switching network includes four primary-side power switches ( , , , and input voltage Among them, the first primary-side power switch transistor The source and the second primary power switch The drains of the transistors are connected to form the left bridge arm, and the third primary power switch transistor is connected to the drain of the transistor. The source and the fourth primary power switch The drains of the two terminals are connected to form the right bridge arm, and the input voltage is... The positive terminal is connected to the first primary power switch transistor. The drain and the third primary power switch The drain and negative terminal are connected to the second primary-side power switch transistor. The source and the fourth primary power switch The source pole.

[0024] The resonant network includes two resonant inductors ( , ), two resonant capacitors ( , ) and two magnetizing inductors ( , ), by the first resonant inductor First resonant capacitor First excitation inductor The first resonant cavity 1 is formed by connecting them in series, and the second resonant inductor is connected in series. Second resonant capacitor Second excitation inductor The two resonant cavities are connected in series to form the second resonant cavity 2, and the parameters of the two resonant cavities are identical. The first resonant inductor... Second resonant inductor Connected to the first left bridge arm respectively; the first magnetizing inductor Second excitation inductor They are respectively connected to the first right axle arm.

[0025] The transformer includes a first high-frequency transformer. Second high-frequency transformer The ratios are respectively , The turns ratio parameters are consistent; in this embodiment, the turns ratio is 2.5:1. First high-frequency transformer Second high-frequency transformer Respectively with the second resonant inductor Second excitation inductor in parallel.

[0026] The secondary-side variable voltage multiplier rectifier structure includes multiple diodes ( , , , , Secondary power switching transistor And two voltage multiplier capacitors ( and First diode The positive terminal and the second diode The negative terminals are connected to form the second left bridge arm, and the third diode... The positive electrode and the fourth diode The negative terminals are connected to form the middle bridge arm, the fifth diode. The positive and secondary power switching transistors The drains are connected to form the second right bridge arm.

[0027] Specifically, the first resonant inductor With the first resonant capacitor Series connection, first resonant inductor Connect the first left bridge arm ( , Point A of the first resonant capacitor Connect the first high-frequency transformer The primary side of the same name terminal, the first high-frequency transformer The original side of the heteronym is connected to the first right bridge arm ( , Point B of the first magnetizing inductance. Then it is connected in parallel to the first high-frequency transformer The primary side; the second resonant inductor With the second resonant capacitor Series connection, second resonant inductor Connected to the first left bridge arm ( , The second resonant capacitor is connected to the high-frequency transformer. The primary side of the same name terminal, the second high-frequency transformer The primary-side non-nominal terminal is then connected to the third primary-side power switch. Fourth primary power switch transistor The source is set as point C, and the second magnetizing inductor is... Then it is connected in parallel to the second high-frequency transformer The original edge.

[0028] First voltage multiplier capacitor One end is connected to a high-frequency transformer The secondary side of the transformer is connected to the same name terminal, and the other end is connected to the second left bridge arm (e.g., at point D); the first high-frequency transformer The secondary side of the transformer with different names and the second high-frequency transformer The secondary side terminals of the same name are connected together and then connected to the middle bridge arm (e.g., at point E); the second voltage multiplier capacitor One end is connected to a high-frequency transformer The other end of the secondary side is connected to the second right bridge arm (such as point F).

[0029] Output filter capacitor One end is connected to the fifth diode. The negative terminal is connected to the secondary power switch transistor, and the other end is connected to the positive terminal. The source, output load With output filter capacitor in parallel.

[0030] The aforementioned ultra-wide gain LLC resonant converter based on multi-mode control achieves four modes of operation on the primary side: series half-bridge, half-bridge, dual half-bridge, and full-bridge half-bridge, by controlling the on / off state of the primary-side power switches. Furthermore, it utilizes a secondary-side voltage multiplier capacitor (the first voltage multiplier capacitor). Second voltage multiplier capacitor and the secondary power switch transistor controlling the secondary side. The conduction and turn-off states can enable the secondary side to operate in two modes: full-bridge rectification and voltage doubler rectification. By combining the primary and secondary modes, the input voltage gain can be significantly broadened.

[0031] The aforementioned ultra-wide gain LLC resonant converter based on multi-mode control can operate in the following six modes to achieve gain widening: series half-bridge to full-bridge rectification mode, half-bridge to full-bridge rectification mode, dual half-bridge to full-bridge rectification mode, full-bridge half-bridge to full-bridge rectification mode, dual half-bridge to voltage doubler rectification mode, and full-bridge half-bridge to voltage doubler rectification mode. Let the gain of the resonant converter be M, where M is the output voltage. Multiply by the transformer primary-secondary turns ratio and then by the input voltage. The ratio of these values, through changes in input voltage, causes changes in gain M, which in turn leads to mode control. When 0.25 ≤ M < 0.4, the converter operates in series half-bridge-full-bridge rectification mode, at which time the primary-side power switch transistors... , Maintain constant off, primary-side power switch , Complementary conduction, with a certain dead zone, secondary power switch Synchronous rectification control is adopted.

[0032] When 0.4 ≤ M < 0.8, the converter operates in half-bridge-full-bridge rectification mode, at which time the primary-side power switch transistors... , Maintain constant off, primary-side power switch , Complementary conduction, with a certain dead zone, secondary power switch Synchronous rectification control is adopted.

[0033] When 0.8 ≤ M < 1.2, the converter operates in dual half-bridge to full-bridge rectification mode, at which time the primary-side power switching transistors... Maintain constant off, primary-side power switch Maintain constant conduction, primary-side power switch , Complementary conduction, with a certain dead zone, secondary power switch Synchronous rectification control is adopted.

[0034] When 1.2 ≤ M < 1.8, the converter operates in full-bridge / half-bridge / full-bridge rectification mode. At this time, the primary-side power switching transistors... , The signals are the same, and the primary power switch is the same. , The signals are the same. , and , Complementary conduction, with a certain dead zone, secondary power switch Synchronous rectification control is adopted.

[0035] When 1.8 ≤ M < 2, the converter operates in dual half-bridge voltage doubler rectifier mode, at which time the primary-side power switch transistors... Maintain constant off, primary-side power switch Maintain constant conduction, primary-side power switch , Complementary conduction, with a certain dead zone, secondary power switch Maintain constant conduction to achieve voltage multiplier rectification.

[0036] When 2≤M≤3, the converter operates in full-bridge / half-bridge voltage doubler rectifier mode, at which time the primary-side power switching transistors... , The signals are the same, and the primary power switch is the same. , The signals are the same. , and , Complementary conduction, with a certain dead zone, secondary power switch Maintain constant conduction to achieve voltage multiplier rectification.

[0037] The aforementioned ultra-wide gain LLC resonant converter based on multi-mode control has six operating modes. In each mode, gain control is achieved by controlling the frequency of the power switches, i.e., pulse frequency modulation. Gain switching between the six operating modes is achieved by sampling the input voltage and determining whether it falls within a preset voltage threshold range to match the corresponding power switch drive. The voltage threshold range corresponds to the gain M, where M is the output voltage. Multiply by the transformer primary-secondary turns ratio and then by the input voltage. The ratio of the turns ratio remains constant, while the change in input voltage corresponds to a change in gain M.

[0038] The following section will introduce the topologies and control strategies for six modes, with a detailed explanation of the lowest gain mode, the series half-bridge to full-bridge rectifier mode, and the highest gain mode, the full-bridge half-bridge to voltage doubler rectifier mode.

[0039] The topology of the series half-bridge-full-bridge rectifier mode is as follows: Figure 2 As shown, the first primary-side power switch transistor Second primary-side power switch Maintain constant off state, third primary-side power switch Fourth primary power switch transistor Complementary conduction, with a certain dead zone, secondary power switch Synchronous rectification control is adopted. Figure 3 The equivalent topology diagram is shown for the series half-bridge-full-bridge rectifier mode topology. Among the six modes, the gain of the series half-bridge-full-bridge rectifier mode at the resonant frequency is 0.25.

[0040] The key waveforms of the steady-state characteristics of the series half-bridge-full-bridge rectifier mode are as follows: Figure 4 As shown, within one switching cycle, the circuit is divided into 8 operating sub-stages, while the operating sub-stages of the second half of the cycle... ~ Compared with the first half of the cycle, the work phase ~ Similarly, only the work phase will be introduced. ~ .

[0041] Work phase a[ - The equivalent circuit is as follows: Figure 5 As shown in (a): time, Turn off, resonant current right , Junction capacitance charging and discharging, time, Drain-source voltage , Drain-source voltage At this time, the current flowing through the secondary diode is 0, and the switching transistor... Keep off, load resistance At this time, the filter capacitor Provide energy.

[0042] Work phase b[ - The equivalent circuit is as follows: Figure 5 As shown in (b): time, , The junction capacitance has completed charging and discharging, and Not yet activated, fourth primary-side power switch The voltage difference between the drain and source terminals Increase to Resonant current Flowing through The body diode creates conditions for its zero-voltage turn-on (ZVS), at which point the magnetizing inductor... , The voltage across the terminals is clamped and does not participate in resonance; the secondary current begins to flow. , and , Zero-voltage turn-on (ZVS), voltage doubler capacitor , Resonance occurs with the primary circuit. , The voltage exhibits a sinusoidal variation, with an average value of 0. , Voltage multiplier capacitor , The voltage difference between the two sides.

[0043] Work phase c[ - The equivalent circuit is as follows: Figure 5 As shown in (c): time, Zero-voltage turn-on, resonant cavity input voltage maintained The resonant circuit operates at , , , and voltage multiplier capacitor , Series resonant state, magnetizing inductance , The voltage across the terminals is clamped and does not participate in resonance; the secondary current continues to flow. , and , Continue conducting to achieve synchronous rectification and excitation current. , Linear growth.

[0044] Work phase d[ - The equivalent circuit is as follows: Figure 5 As shown in (d): At that moment, the resonant current With excitation current , To maintain consistency, magnetizing inductance , The voltage across the terminals is no longer clamped and re-enters resonance; the secondary current gradually decreases to 0, and the switching transistor... Turn off, diode , and switching transistors Achieving zero-current turn-off (ZCS) with load resistance At this time, the filter capacitor Provide energy.

[0045] The topology of the half-bridge-full-bridge rectifier mode is as follows: Figure 6 As shown, the primary-side power switch transistor , Maintain constant off, primary-side power switch , Complementary conduction, with a certain dead zone, secondary power switch Synchronous rectification control is employed. Among the six modes, the half-bridge-full-bridge rectification mode has a gain of 0.5 at the resonant frequency.

[0046] The topology of the dual half-bridge to full-bridge rectifier mode is as follows: Figure 7 As shown, the primary-side power switch transistor Maintain constant off, primary-side power switch Maintain constant conduction, primary-side power switch , Complementary conduction, with a certain dead zone, secondary power switch Synchronous rectification control is employed. Among the six modes, the gain of the dual half-bridge to full-bridge rectification mode is 1 at the resonant frequency.

[0047] The topology of the full-bridge, half-bridge, and full-bridge rectifier modes is as follows: Figure 8 As shown, the primary-side power switch transistor , The signals are the same, and the primary power switch is the same. , The signals are the same. , and , Complementary conduction, with a certain dead zone, secondary power switch Synchronous rectification control is employed. Among the six modes, the gain of the full-bridge / half-bridge / full-bridge rectifier mode at the resonant frequency is 1.5.

[0048] The topology of the dual half-bridge voltage doubler rectifier mode is as follows: Figure 9 As shown, the primary-side power switch transistor Maintain constant off, primary-side power switch Maintain constant conduction, primary-side power switch , Complementary conduction, with a certain dead zone, secondary power switch Maintaining constant conduction enables voltage multiplier rectification. Among the six modes, the gain of the dual half-bridge voltage multiplier rectification mode is 2 at the resonant frequency.

[0049] The topology of the full-bridge / half-bridge voltage doubler rectifier mode is as follows: Figure 10 As shown, the primary-side power switch transistor , The signals are the same, and the primary power switch is the same. , The signals are the same. , and , Complementary conduction, with a certain dead zone, secondary power switch Maintaining constant conduction enables voltage multiplier rectification. Among the six modes, the full-bridge / half-bridge voltage multiplier rectification mode has a gain of 3 at the resonant frequency.

[0050] The key waveforms of the steady-state characteristics of the full-bridge and half-bridge voltage doubler rectifier modes are as follows: Figure 11 As shown, within one switching cycle, the circuit is divided into 8 working sub-stages, with four in each of the upper and lower cycles. Since the working stages in the upper half of the cycle are not similar to those in the lower half of the cycle, each of the 8 working stages will be introduced in detail.

[0051] Work phase a[ - The equivalent circuit is shown in Figure 12(a): time, , Turn off, resonant current right , , , Junction capacitance charging and discharging, resonant current right , Junction capacitance charging and discharging, time, , Drain-source voltage , , , Drain-source voltage , At this time, the current flowing through the secondary side is 0, and the load resistance is... At this time, the filter capacitor Provide energy.

[0052] Work phase b[ - The equivalent circuit is shown in Figure 12(b): time, , , , The junction capacitance has completed charging and discharging, and , Not yet activated; voltage difference between the midpoint of the left primary arm and the midpoint of the right primary arm. Second primary-side power switch The voltage difference between the drain and source terminals Increase to Resonant current , express and , Flowing through , Body diode, Flowing through Body diode, for , Zero-voltage turn-on (ZVS) creates the conditions for the magnetizing inductor to... , The voltage across the terminals is clamped and does not participate in resonance; the secondary current begins to flow. and , The secondary side voltage is clamped at Clamping position, The secondary side voltage is clamped at , , The voltage changes in a sinusoidal pattern, with an average value of , of which Output voltage, , Voltage multiplier capacitor , The voltage difference between the two sides.

[0053] Work phase c[ - The equivalent circuit is shown in Figure 12(c): time, and Zero-voltage turn-on, the input voltage of the two resonant cavities remains unchanged. , The resonant circuit operates at , , , Series resonant state, magnetizing inductance , The voltage across the terminals is clamped and does not participate in resonance; the secondary current continues to flow. and To achieve synchronous rectification, excitation current , Linear growth.

[0054] Work phase d[ - The equivalent circuit is shown in Figure 12(d): At that moment, the resonant current and They are respectively equal to the excitation current and Magnetizing inductor , The voltage across the terminals is no longer clamped and re-enters resonance; the secondary current gradually decreases to 0, and the switching transistor... The diode remains conducting. Achieving zero-current turn-off (ZCS) with load resistance At this time, the filter capacitor Provide energy.

[0055] Work phase e[ - The equivalent circuit is shown in Figure 12(e): time, , Turn off, resonant current right , , , Junction capacitance charging and discharging, resonant current right , Junction capacitance charging and discharging, time, , Drain-source voltage , , , Drain-source voltage , At this time, the current flowing through the secondary side is 0, and the load resistance is... At this time, the filter capacitor Provide energy.

[0056] Work phase f[ - The equivalent circuit is shown in Figure 12(f): time, , , , The junction capacitance has completed charging and discharging, and , Not yet open. , Descending to Resonant current , Flowing through , Body diode, Flowing through Body diode, for , Zero-voltage turn-on (ZVS) creates the conditions for the magnetizing inductor to... , The voltage across the terminals is not clamped and participates in resonance, allowing the secondary current to begin flowing. and Voltage multiplier capacitor , Starting with transformer , Charging for energy storage The secondary side voltage is clamped at , The secondary side voltage is clamped at , , The voltage changes in a sinusoidal pattern, with an average value of At this time, the load resistance Still by the filter capacitor Provide energy.

[0057] Work phase g[ - The equivalent circuit is shown in Figure 12(g): time, and Zero-voltage turn-on, the input voltage of the two resonant cavities remains unchanged. , The resonant circuit operates at , , , , , In the series-parallel resonant state, the secondary current continues to flow through... and Give a voltage multiplier capacitor , Charging, excitation current , The load resistance increases linearly, at which point... Still by the filter capacitor Provide energy.

[0058] Work phase h[ - The equivalent circuit is shown in Figure 12(h): At that moment, the resonant current and They are respectively equal to the excitation current and The secondary current gradually decreases to 0, and the voltage multiplier capacitor... , Charging complete, waiting for the dead zone to end and discharge, switching transistor The diode remains conducting. Achieving zero-current turn-off (ZCS) requires the load resistance to... Still by the filter capacitor Provide energy.

[0059] Simulation waveforms of key parameters of the ultra-wide gain LLC resonant converter based on multi-mode control in the series half-bridge-full-bridge rectified mode are shown below. Figure 13 As shown in (a), the simulation waveforms of key parameters in the full-bridge half-bridge voltage doubler rectifier mode are shown. Figure 13 As shown in (b). In the figure, The first primary-side power switch The voltage drive signal between the gate and source; The second primary-side power switch The voltage drive signal between the gate and source; The third primary-side power switch The voltage drive signal between the gate and source; The fourth primary-side power switch The voltage drive signal between the gate and source; For the current flowing through the first diode The current flows from the positive terminal to the negative terminal; For the flow through the second diode The current flows from the positive terminal to the negative terminal; For the current flowing through the fifth diode The current flows from the positive terminal to the negative terminal; For the power switch transistor on the secondary side The current flows from the source to the drain. For the flow through the second diode and secondary power switching transistor The current; For the current flowing through the first diode and the fifth diode The current.

[0060] This invention combines four primary-side operating modes with two secondary-side rectifier modes to form six progressively increasing gain operating modes, enabling the converter to achieve stable output over a twelve-fold ultra-wide input voltage range from 40V to 480V. Each mode requires pulse frequency modulation within a narrow frequency range of 120kHz to 180kHz, greatly simplifying magnetic component design and avoiding electromagnetic compatibility and control loop stability issues associated with wide-frequency regulation. All modes achieve zero-voltage turn-on of the primary and secondary-side switches and zero-current turn-off of the secondary-side rectifier, exhibiting excellent soft-switching characteristics. The narrow gain range allows for a larger magnetizing inductance value, effectively reducing cycle energy and conduction losses. All six modes are based on the same topology; switching requires only changes to the drive logic, without the need for additional components or hardware modifications, resulting in high topology reuse, simplified control implementation, and high reliability.

[0061] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A topology for an ultra-wide gain LLC resonant converter based on multi-mode control, characterized in that, This includes the primary-side switching network, resonant network, transformer, secondary-side variable voltage multiplier rectifier structure, and output filter capacitor. With output load ; The primary-side switching network includes four primary-side power switches ( , , , and input voltage Among them, the first primary-side power switch transistor The source and the second primary power switch The drains of the transistors are connected to form the left bridge arm, and the third primary power switch transistor is connected to the drain of the transistor. The source and the fourth primary power switch The drains of the two terminals are connected to form the right bridge arm, and the input voltage is... The positive terminal is connected to the first primary power switch transistor. The drain and the third primary power switch The drain and negative terminal are connected to the second primary-side power switch transistor. The source and the fourth primary power switch The source pole; The resonant network includes two resonant inductors ( , ), two resonant capacitors ( , ) and two magnetizing inductors ( , ), by the first resonant inductor First resonant capacitor First excitation inductor The first resonant cavity is formed by connecting them in series, and the second resonant inductor is connected in series. Second resonant capacitor Second excitation inductor The second resonant cavity is formed by connecting them in series, and the first resonant inductor is connected in series. Second resonant inductor Connected to the first left bridge arm respectively; the first magnetizing inductor Second excitation inductor They are respectively connected to the first right bridge arm; The transformer includes a first high-frequency transformer. Second high-frequency transformer First high-frequency transformer Second high-frequency transformer Respectively with the second resonant inductor Second excitation inductor in parallel; The secondary-side variable voltage multiplier rectifier structure includes multiple diodes ( , , , , Secondary power switching transistor And two voltage multiplier capacitors ( , ); First diode The positive terminal and the second diode The negative terminals are connected to form the second left bridge arm, and the third diode... The positive electrode and the fourth diode The negative terminals are connected to form the middle bridge arm, the fifth diode. The positive and secondary power switching transistors The drains are connected to form the second right bridge arm.

2. The ultra-wide gain LLC resonant converter topology based on multi-mode control according to claim 1, characterized in that, First resonant inductor With the first resonant capacitor Series connection, first resonant inductor Connect the first left bridge arm and the first resonant capacitor. Connect the first high-frequency transformer The primary side of the same name terminal, the first high-frequency transformer The primary side of the non-standard terminal is connected to the first right bridge arm, the first magnetizing inductor. Parallel connection to the first high-frequency transformer The original edge.

3. The ultra-wide gain LLC resonant converter topology based on multi-mode control according to claim 1, characterized in that, Second resonant inductor With the second resonant capacitor Series connection, second resonant inductor The second resonant capacitor is connected to the first left bridge arm and to the high-frequency transformer. The primary side of the same name terminal, the second high-frequency transformer The primary-side non-nominal terminal is then connected to the third primary-side power switch. Fourth primary power switch transistor The source of the second magnetizing inductor Parallel connection to the second high-frequency transformer The original edge.

4. The ultra-wide gain LLC resonant converter topology based on multi-mode control according to claim 1, characterized in that, First voltage multiplier capacitor One end is connected to a high-frequency transformer The second-side terminal is connected to the same name, and the other end is connected to the second left bridge arm; the first high-frequency transformer The secondary side of the transformer with different names and the second high-frequency transformer The secondary side terminals of the two capacitors are connected together and then connected to the middle bridge arm; the second voltage multiplier capacitor... One end is connected to a high-frequency transformer One end is the secondary side, and the other end is connected to the second right bridge arm.

5. The ultra-wide gain LLC resonant converter topology based on multi-mode control according to claim 1, characterized in that, First high-frequency transformer Second high-frequency transformer The ratios are respectively , The transformer ratio parameters are consistent.

6. The ultra-wide gain LLC resonant converter topology based on multi-mode control according to claim 1, characterized in that, By controlling the on / off state of the primary-side power switch, the primary side can operate in series half-bridge, half-bridge, double half-bridge, and full-bridge half-bridge modes.

7. The ultra-wide gain LLC resonant converter topology based on multi-mode control according to claim 1, characterized in that, The secondary power switch is controlled by two voltage multiplier capacitors. The conduction and turn-off states enable the secondary side to operate in two modes: full-bridge rectification and voltage multiplier rectification. Gain broadening is achieved through the following six modes: series half-bridge-full-bridge rectification, half-bridge-full-bridge rectification, dual half-bridge-full-bridge rectification, full-bridge half-bridge-full-bridge rectification, dual half-bridge-voltage multiplier rectification, and full-bridge half-bridge-voltage multiplier rectification.

8. The ultra-wide gain LLC resonant converter topology based on multi-mode control according to claim 1, characterized in that, Let the gain of the resonant converter be M, and M be the output voltage. Multiply by the transformer primary-secondary turns ratio and then by the input voltage. The ratio; When 0.25 ≤ M < 0.4, the converter operates in series half-bridge-full-bridge rectification mode, at which time the first primary-side power switch transistor... Second primary-side power switch Maintain constant off state, third primary-side power switch Fourth primary power switch transistor The secondary power switch S5 is controlled by synchronous rectification due to the complementary conduction and the existence of a dead zone. When 0.4 ≤ M < 0.8, the converter operates in half-bridge-full-bridge rectification mode, at which time the third primary-side power switch transistor... Fourth primary power switch transistor Maintain constant off state, first primary-side power switch Second primary-side power switch Complementary conduction, but with a dead time, secondary power switch transistor Synchronous rectification control is adopted; When 0.8 ≤ M < 1.2, the converter operates in the dual half-bridge to full-bridge rectification mode, at which time the third primary-side power switch transistor... Maintain constant off, fourth primary-side power switch Maintain constant conduction, the first primary-side power switch Second primary-side power switch Complementary conduction, but with a dead time, secondary power switch transistor Synchronous rectification control is adopted; When 1.2 ≤ M < 1.8, the converter operates in full-bridge / half-bridge / full-bridge rectification mode. At this time, the first primary-side power switch... Fourth primary power switch transistor The signals are the same, the second primary-side power switch Third primary power switch transistor The signals are the same, the first primary-side power switch Fourth primary power switch transistor With the second primary-side power switch Third primary power switch transistor Complementary conduction, but with a dead time, secondary power switch transistor Synchronous rectification control is adopted; When 1.8 ≤ M < 2, the converter operates in dual half-bridge voltage doubler rectifier mode, at which time the third primary-side power switch transistor... Maintain constant off, fourth primary-side power switch Maintain constant conduction, the first primary-side power switch Second primary-side power switch Complementary conduction, but with a dead time, secondary power switch transistor Maintain constant conduction to achieve voltage multiplier rectification; When 2≤M≤3, the converter operates in full-bridge / half-bridge voltage doubler rectifier mode, at which time the first primary-side power switch transistor... Fourth primary power switch transistor The signals are the same, the second primary-side power switch Third primary power switch transistor The signals are the same, the first primary-side power switch Fourth primary power switch transistor With the second primary-side power switch Third primary power switch transistor Complementary conduction, but with a dead time, secondary power switch transistor Maintain constant conduction to achieve voltage multiplier rectification.

9. The ultra-wide gain LLC resonant converter topology based on multi-mode control according to claim 8, characterized in that, In each mode, gain control is achieved by controlling the frequency of the primary-side power switch, i.e., pulse frequency modulation. The gain switching of the six operating modes is achieved by sampling the input voltage and determining the voltage threshold range into which the input voltage falls to match the corresponding power switch drive.

10. The ultra-wide gain LLC resonant converter topology based on multi-mode control according to claim 9, characterized in that, The voltage threshold range corresponds to the gain M, where M is the output voltage. Multiply by the transformer primary-secondary turns ratio and then by the input voltage. The ratio of the turns ratio remains constant, while the change in input voltage corresponds to a change in gain M.

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