Voltage-lifted LLC resonant converter and control method thereof

Abstract

This invention discloses a voltage-boosting LLC resonant converter and its control method, comprising a control chip, a DC power supply, a bus voltage regulation circuit, a full-bridge power inverter circuit, an LLC resonant transformer circuit, and a rectifier-filter output circuit. The DC power supply is electrically connected to the control chip. The bus voltage regulation circuit includes a bus drive branch, a bus capacitor branch, and a bus pre-charge regulation branch. The bus drive branch is electrically connected to the DC power supply. The bus capacitor branch is electrically connected to the bus drive branch. The bus pre-charge regulation branch is connected to both the bus drive branch and the bus capacitor branch. The full-bridge power inverter circuit is electrically connected to both the control chip and the bus capacitor branch. The LLC resonant transformer circuit is electrically connected to the full-bridge power inverter circuit. The rectifier-filter output circuit is electrically connected to the LLC resonant transformer circuit. The method is applied to the aforementioned voltage-boosting LLC resonant converter. This invention can achieve output voltage boosting over a wide range.

Description

Technical Field

[0001] This invention relates to the field of resonant converter technology, specifically to a voltage-boosting LLC resonant converter and its control method. Background Technology

[0002] In the fields of wide-voltage charging and new energy power conversion, LLC resonant converters, as isolated DC / DC power conversion devices, mainly rely on the resonant cavity to achieve efficient conversion of primary-side AC power to secondary-side DC power. They rely on frequency conversion regulation to change the output voltage. With their advantages of high efficiency, low loss and excellent electrical isolation performance, they are widely used in various voltage conversion equipment.

[0003] Currently, the voltage output regulation method of traditional LLC resonant converters mainly relies on changing the switching frequency to adjust the impedance characteristics of the resonant cavity, thereby adjusting the DC voltage gain of the system and achieving output voltage regulation. However, in actual operation, when the switching frequency deviates from the resonant frequency, the voltage gain curve of the LLC resonant converter tends to flatten out, and the dynamic voltage regulation performance is significantly reduced. This results in a significant narrowing of the effective voltage adjustable range of the LLC resonant converter, making it difficult to achieve a wide range of output voltage increases and failing to adapt to the multi-condition and wide-range voltage output application scenarios of ultra-wide voltage chargers. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a voltage-boosting LLC resonant converter, comprising: Control chip; DC power supply, which is electrically connected to the control chip; The bus voltage regulation circuit includes a bus drive branch, a bus capacitor branch, and a bus pre-charge regulation branch; the bus drive branch is electrically connected to a DC power supply; the bus capacitor branch includes a first capacitor. and the second capacitor First capacitor With the second capacitor Electrical connection, first capacitor and the second capacitor It is also electrically connected to the bus drive branch; one end of the bus precharge control branch is connected to the bus drive branch, and the other end is connected to the second capacitor. Electrical connection; the control chip is connected to the bus drive branch and the first capacitor respectively. Second capacitor and the electrical connection of the busbar pre-charge control branch; The full-bridge power inverter circuit is connected to the control chip and the first capacitor. and the second capacitor Electrical connection; LLC resonant transformer circuit, which is electrically connected to the full-bridge power inverter circuit. The rectifier and filter output circuit is electrically connected to the LLC resonant transformer circuit.

[0005] Furthermore, the bus drive branch includes a first power diode. First power MOSFET Second power diode and the second power MOSFET First power diode The anode is electrically connected to the positive terminal of the DC power supply, and the first power diode... Cathode and first capacitor Electrical connection; first power MOSFET The drain is electrically connected to the positive terminal of the DC power supply, the first power MOSFET The source diode is electrically connected to the bus pre-charge control branch; the second power diode... The anode is electrically connected to the negative terminal of the DC power supply, and the second power diode... The cathode is electrically connected to the bus pre-charge control branch; the second power MOSFET is also connected. The drain is electrically connected to the negative terminal of the DC power supply, the second power MOSFET. Source and second capacitor Electrical connection; the control chip is connected to the first power MOSFET respectively. Gate and second power MOSFET Gate electrical connection.

[0006] Furthermore, the bus pre-charge control branch includes a pre-charge resistor. and control switch Pre-charge resistor One end is connected to the first power MOSFET Source and second power diode Between cathodes, pre-charge resistance The other end is connected to the first capacitor. With the second capacitor Between; control switch With pre-charge resistance Parallel connection, control switch It is also electrically connected to the control chip.

[0007] Furthermore, the full-bridge power inverter circuit includes a third power MOSFET. Fourth power MOSFET Fifth power MOSFET and the sixth power MOSFET Third power MOSFET Drain and first capacitor Electrical connection, third power MOSFET Source and fourth power MOSFET Drain connection, fourth power MOSFET Source and second capacitor Electrical connection, fifth power MOSFET Drain and third power MOSFET Drain connection, fifth power MOSFET Source and sixth power MOSFET Drain connection, sixth power MOSFET Source and fourth power MOSFET Source electrical connection; control chip is connected to the third power MOSFET respectively. Gate, fourth power MOSFET Gate, fifth power MOSFET Gate and sixth power MOSFET Gate electrical connection.

[0008] Furthermore, the LLC resonant transformer circuit includes a resonant inductor. Resonant capacitor and high frequency transformers Resonant inductor With resonant capacitor A resonant cavity is formed, with one end of the resonant cavity connected to a third power MOSFET. With the fourth power MOSFET Between them, the other end is connected to the fifth power MOSFET. With the sixth power MOSFET Between; high-frequency transformer The primary side is connected to the resonant inductor. With resonant capacitor Between, high-frequency transformer The secondary side is connected to the rectifier filter output circuit.

[0009] Furthermore, the rectifier-filter output circuit includes a rectifier-freewheeling branch and a DC filter branch; the rectifier-freewheeling branch and the high-frequency transformer... The secondary side is electrically connected; the DC filter branch is connected in parallel with the rectifier freewheeling branch.

[0010] Furthermore, the DC filter branch includes filter capacitors. and equivalent load ; Filter capacitor Connected in parallel with the rectifier freewheeling branch; equivalent load With filter capacitor in parallel.

[0011] Furthermore, the present invention also provides a control method for a voltage-raised LLC resonant converter, the method being applied to the voltage-raised LLC resonant converter described above, comprising the following steps: S01: DC power supply is the first capacitor. and the second capacitor During charging, the control chip detects the DC power supply output voltage. Voltage at the first capacitor terminal and the voltage at the second capacitor terminal and calculate and and The difference and , and then and Compared with the preset differential pressure threshold Compare; S02: If < and < The control chip controls the bus pre-charge regulation branch to be in the first state, causing the first capacitor to... With the second capacitor In series, the DC power supply stops supplying power to the first capacitor. With the second capacitor Charging; if not, the control chip controls the pre-charge regulation branch of the bus to be in the second state, causing the first capacitor to... With the second capacitor In parallel connection, when the first capacitor With the second capacitor When connected in parallel, the DC power supply continues to supply power to the first capacitor. and the second capacitor Charge until satisfied. < and < Subsequently, the control chip controls the bus pre-charge regulation branch to be in the first state, causing the first capacitor to... With the second capacitor In series, the DC power supply stops supplying power to the first capacitor. With the second capacitor Charge; S03: The bus pre-charge control branch is in the first or second state, and the voltage at the first capacitor terminal is... With the voltage at the second capacitor terminal After stabilization, the control chip adjusts the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum Calculate the required output voltage for the LLC resonant transformer circuit. ; Obtain the maximum output voltage conversion ratio corresponding to the LLC resonant transformer circuit and calculate , and then With output voltage Perform a comparison and generate comparison results; S04: The control chip controls the bus pre-charge regulation branch to be in the first or second state based on the comparison result, and controls the on / off state of the bus drive branch to change the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum Simultaneously, inversion and resonant boosting conversion are performed through a full-bridge power inverter circuit and an LLC resonant transformer circuit to resonantly boost the output voltage. The output range generates high-frequency alternating current and outputs it to the rectifier and filter output circuit; S05: The rectifier and filter output circuit rectifies and smooths the high-frequency AC power to generate DC power.

[0012] Furthermore, the step of basing the voltage at the first capacitor terminal... With the voltage at the second capacitor terminal sum Calculate the required output voltage for the LLC resonant transformer circuit. The calculation process is as follows: ; ; ; ; ; In the formula, For high frequency transformers The number of turns ratio, For switching frequency, For high frequency transformers The resonant frequency, It is the ratio between the switching frequency and the resonant frequency. It is a resonant inductor. It is a resonant capacitor. For quality factor, For high frequency transformers The equivalent load connected to the secondary side, For high frequency transformers The primary magnetizing inductance, This is the inductance ratio between the magnetizing inductance and the resonant inductance.

[0013] Furthermore, the inversion and resonant boost conversion via the full-bridge power inverter circuit and LLC resonant transformer circuit includes the following steps: The control chip comparison result is as follows When needed, the control chip controls the regulating switch. In the first state, the pre-charge resistor is... Bypassed and controlling the first power MOSFET The drive signal is a low-level signal, and the second power MOSFET... The drive signal is a high-level signal to turn off the first power MOSFET. Turn on the second power MOSFET Simultaneously drive the third power MOSFETs Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction brings the entire circuit to the first resonant boost state, and lowers the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum The inverter generates an AC square wave voltage; the control chip adjusts the third power MOSFET in the first resonant boost state. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET The switching frequency is adjusted to control the voltage amplitude of the AC square wave voltage, which is then passed through a high-frequency transformer. The adjusted AC square wave voltage is resonantly boosted to raise the output voltage. The output range is ; The control chip comparison result is as follows When needed, the control chip controls the regulating switch. In the second state, the pre-charge resistor is... The circuit is connected to the circuit, and the voltage at the first capacitor terminal is continuously sampled. and the voltage at the second capacitor terminal Then the voltage at the first capacitor terminal With the voltage at the second capacitor terminal To make a comparison, if The control chip controls the first power MOSFET. With the second power MOSFET The drive signal is a low-level signal to turn off the first power MOSFET. With the second power MOSFET Simultaneously drive the third power MOSFETs Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction causes the entire circuit to be in a second resonant boost state, and also lowers the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum Inverting to generate AC square wave voltage; if Then control the first power MOSFET With the second power MOSFET The drive signal is a high-level signal to turn on the first power MOSFET. With the second power MOSFET Then drive the third power MOSFET respectively. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction brings the entire circuit to the third resonant boost state, and also lowers the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum The inverter generates an AC square wave voltage; the control chip adjusts the third power MOSFET in the second or third resonant boost state. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET The switching frequency is adjusted to control the voltage amplitude of the AC square wave voltage, which is then passed through a high-frequency transformer. The adjusted AC square wave voltage is resonantly boosted to raise the output voltage. The output range is .

[0014] The beneficial effects of this application are as follows: When the voltage-boosting LLC resonant converter is working, the control chip first coordinates the DC power supply to power the bus voltage regulation circuit. The bus voltage regulation circuit includes a bus drive branch, a bus capacitor branch, and a bus pre-charge regulation branch. After the bus drive branch is powered on, combined with the synergistic effect of the bus capacitor branch composed of the first and second capacitors and the bus pre-charge regulation branch, dynamic charging and stable regulation of the bus capacitor branch are achieved, avoiding the inrush current generated by the direct series connection of the first and second capacitors at startup, which could damage the devices. Specifically, the control chip detects the DC power supply output voltage, the voltage at the end of the first capacitor, and the voltage at the end of the second capacitor in real time, and calculates the difference between the two and the DC power supply output voltage. By comparing it with a preset voltage difference threshold, the charging state of the first and second capacitors is determined. When the voltage difference between the first and second capacitors and the DC power supply output voltage is less than a preset voltage difference threshold, the control chip controls the bus pre-charge regulation branch to enter the first state, connecting the first and second capacitors in series, and the DC power supply stops charging. Otherwise, it enters the second state, connecting the first and second capacitors in parallel, continuing charging until the voltage difference is less than the preset voltage difference threshold, at which point it switches to series connection. This process ensures stable regulation of the bus DC voltage corresponding to the first and second capacitors, thus forming a bus DC voltage reference of the sum of the voltages at the terminals of the first and second capacitors within the full-bridge power inverter circuit. After the voltages at the terminals of the first and second capacitors stabilize, the control chip calculates the output voltage required by the downstream load and selectively controls the on / off state of the bus drive branch to change the connection method of the first and second capacitors and their connection relationship with the DC power supply, thereby flexibly adjusting the bus DC voltage applied to the full-bridge power inverter circuit. Under the action of the PWM drive signal output by the control chip, the full-bridge power inverter circuit can convert the bus DC voltage into an AC square wave voltage and send it to the LLC resonant transformer circuit. The LLC resonant transformer circuit resonates and boosts the AC square wave voltage. This is achieved by adjusting the switching frequency of the full-bridge power inverter circuit to raise or lower the AC square wave voltage. Simultaneously, it provides electrical isolation between the input and output sides of the LLC resonant transformer circuit. This eliminates excessive reliance on frequency converter regulation, converting the AC square wave voltage into a high-frequency AC output. This avoids the problems of a flat voltage gain curve and narrow adjustable range caused by the switching frequency deviating from the resonant point in traditional solutions. The rectifier and filter output circuit rectifies and smooths this high-frequency AC power, ultimately converting it into a smooth DC output. Throughout this process, by adjusting the connection method of the bus voltage regulation circuit according to the output voltage required by the downstream load, the DC bus voltage input to the full-bridge power inverter circuit is actively raised or lowered, thereby adjusting the input voltage value of the LLC resonant transformer circuit. This achieves efficient output voltage boosting over a wide range, meeting the voltage output requirements of ultra-wide voltage chargers under various operating conditions, thus realizing an ultra-wide voltage regulation process. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the circuit topology of the voltage-lift LLC resonant converter in the embodiment; Figure 2 for Figure 1 A schematic diagram of the topology of the bus voltage regulation circuit; Figure 3 for Figure 1 A schematic diagram of the topology of the rectifier filter output circuit; Figure 4 This is a schematic diagram of the control flow of the voltage-boosted LLC resonant converter in the embodiment; Figure 5 This is a schematic diagram of the circuit operation of the voltage-boosting LLC resonant converter in the first resonant boost state in the embodiment; Figure 6 This is a schematic diagram of the circuit operation of the voltage-boosting LLC resonant converter in the second resonant boost state in the embodiment; Figure 7 This is a schematic diagram of the circuit operation of the voltage-boosting LLC resonant converter in the third resonant boost state in the embodiment.

[0016] Explanation of reference numerals in the attached figures 1. DC power supply; 2. Bus voltage regulation circuit; 21. Bus drive branch; 22. Bus capacitor branch; 23. Bus precharge regulation branch; 3. Full-bridge power inverter circuit; 4. LLC resonant transformer circuit; 5. Rectifier and filter output circuit; 51. Rectifier freewheeling branch; 52. DC filter branch. Detailed Implementation

[0017] The following drawings will disclose several embodiments of the present invention. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not essential. Furthermore, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simple schematic manner.

[0018] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings: Example 1 Reference Figure 1 , Figure 1This is a schematic diagram of the circuit topology of the voltage-raised LLC resonant converter in this embodiment. This embodiment provides a voltage-raised LLC resonant converter, including a control chip (not shown), a DC power supply 1, a bus voltage regulation circuit 2, a full-bridge power inverter circuit 3, an LLC resonant transformer circuit 4, and a rectifier and filter output circuit 5. The circuit consists of several interconnected circuits: DC power supply 1 is electrically connected to the control chip, providing initial DC power to the entire circuit and an auxiliary power supply reference to ensure normal power-on operation; bus voltage regulation circuit 2 is electrically connected to both DC power supply 1 and the control chip, receiving the regulation signal output by the control chip to dynamically regulate and stabilize the initial DC power output by DC power supply 1, resulting in a stable and adjustable bus DC voltage; full-bridge power inverter circuit 3 is electrically connected to both bus voltage regulation circuit 2 and the control chip, receiving the regulated bus DC voltage and responding to the PWM drive signal output by the control chip to invert the bus DC voltage into an AC square wave voltage; LLC resonant transformer circuit 4 is electrically connected to the full-bridge power inverter circuit 3, receiving the AC square wave voltage and using the resonant frequency conversion principle to achieve voltage boosting and electrical isolation, converting the AC square wave voltage into high-frequency AC power; and rectifier and filter output circuit 5 is electrically connected to the LLC resonant transformer circuit 4, rectifying and filtering the high-frequency AC power output by the LLC resonant transformer circuit 4 to convert it into stable DC power and supply power to the downstream load.

[0019] Please refer to the following: Figure 2 , Figure 2 for Figure 1 A schematic diagram of the topology of the bus voltage regulation circuit. The bus voltage regulation circuit 2 includes a bus drive branch 21, a bus capacitor branch 22, and a bus pre-charge regulation branch 23; the bus drive branch 21 is electrically connected to the DC power supply 1; the bus capacitor branch 22 includes a first capacitor. and the second capacitor First capacitor With the second capacitor Electrical connection, first capacitor and the second capacitor It is also electrically connected to the bus drive branch 21; one end of the bus precharge control branch 23 is connected to the bus drive branch 21, and the other end is connected to the second capacitor. Electrical connection; the control chip is connected to the bus drive branch 21 and the first capacitor respectively. Second capacitor The bus pre-charge control branch 23 is electrically connected; the full-bridge power inverter circuit 3 is connected to the control chip and the first capacitor respectively. and the second capacitor Electrical connection.

[0020] In this example, DC power supply 1 continuously outputs an initial DC current of a preset amplitude, which provides power input to the bus voltage regulation circuit 2. The initial DC current flows into the bus capacitor branch 22 through the bus drive branch 21, enabling the first capacitor to achieve... With the second capacitor The charging process; on the other hand, it provides stable auxiliary power to the control chip. After the control chip is powered on, it samples the DC power supply output voltage and the first capacitor throughout the entire process. Terminal voltage, second capacitor The terminal voltage is determined by a preset differential voltage threshold within the control chip, which dynamically controls the operating state of the bus drive branch 21 and the bus pre-charge regulation branch 23 to realize the first capacitor With the second capacitor The series and parallel states are dynamically switched, that is, the output voltage of the DC power supply and the first capacitor are calculated separately. Terminal voltage and second capacitor The voltage difference between the two terminals is compared with a preset voltage difference threshold. When the DC power supply output voltage is equal to that of the first capacitor... The voltage difference between the terminals is less than a preset voltage difference threshold, and the DC power supply output voltage is less than that of the second capacitor. The voltage difference between the terminals is also less than the preset voltage difference threshold, i.e., the first capacitor With the second capacitor When fully charged, DC power supply 1 stops supplying power to the first capacitor. With the second capacitor During charging, the control chip outputs a high-level control signal to control the bus pre-charge control branch 23 to be in the first state, thus bypassing the bus pre-charge control branch 23. In other words, the first state is when the bus pre-charge control branch 23 is bypassed. At this time, the first capacitor... With the second capacitor Series connection, first capacitor With the second capacitor Both terminal voltages are stabilized at half the DC power supply output voltage, providing a stable bus DC voltage foundation for the subsequent low-voltage range output of the LLC resonant transformer circuit 4; when the DC power supply output voltage is equal to that of the first capacitor... The voltage difference between the terminals is greater than or equal to a preset voltage difference threshold, or the DC power supply output voltage is greater than or equal to the voltage difference between the terminals and the second capacitor. The voltage difference between the terminals is greater than or equal to a preset voltage difference threshold, i.e., the first capacitor Or the second capacitor If not fully charged, determine the first capacitor. Or the second capacitor When the voltage drops and energy storage is insufficient, failing to reach the steady-state operating standard, the control chip outputs a low-level regulation signal to control the bus pre-charge regulation branch 23 to be in the second state. That is, in the second state, the bus pre-charge regulation branch 23 is connected to the circuit. At this time, the first capacitor... With the second capacitor In parallel, DC power supply 1, through bus drive branch 21 and bus pre-charge control branch 23, supplies power to the first capacitor. With the second capacitor Perform current-limited charging to slowly replenish the first capacitor. With the second capacitor Energy storage suppresses instantaneous inrush currents during power-on and voltage drop, protecting the components of bus capacitor branch 22 and subsequent full-bridge power inverter circuit 3, thereby ensuring the safety of the first capacitor. With the second capacitor Both terminal voltages are stable at the DC power supply output voltage. The bus pre-charge control branch 23 is in either the first or second state, and the first capacitor... Terminal voltage and second capacitor After the terminal voltage is fully charged and stabilized, the control chip uses the first capacitor... Terminal voltage and second capacitor The sum of the terminal voltages is used to calculate the output voltage required by the LLC resonant transformer circuit 4, which is also the voltage required by the first capacitor. Terminal voltage and second capacitor The sum of the terminal voltages is the bus DC voltage applied to the full-bridge power inverter circuit 3. The maximum conversion ratio of the output voltage corresponding to the LLC resonant transformer circuit 4 is obtained. Based on the maximum conversion ratio and the DC power supply output voltage, the maximum reference output voltage of the LLC resonant transformer circuit 4 is calculated. The calculated output voltage is compared with the maximum reference output voltage. Based on the comparison result, the control chip controls the bus pre-charge regulation branch 23 to be in either the first or second state. That is, when the output voltage is less than the maximum reference output voltage, the first capacitor... Terminal voltage and second capacitor The terminal voltage needs to be stabilized at half of the DC power supply output voltage, and the control chip controls the bus pre-charge regulation branch 23 to be in the first state; while when the output voltage is greater than or equal to the maximum reference output voltage, the first capacitor... Terminal voltage and second capacitor The terminal voltage needs to be stabilized at the DC power supply output voltage. The control chip controls the bus pre-charge regulation branch 23 to be in the second state. At the same time, the control chip controls the on / off state of the switching transistor in the bus drive branch 21 to change the first capacitor. With the second capacitor The connection method (series or parallel) and its connection relationship with DC power supply 1 are used to flexibly adjust the bus DC voltage applied to the full-bridge power inverter circuit 3.

[0021] The full-bridge power inverter circuit 3 receives the stabilized DC bus voltage from the bus voltage regulation circuit 2 and, under the action of the PWM drive signal output by the control chip, inverts the DC bus voltage into an AC square wave voltage, which is then output to the LLC resonant transformer circuit 4. The AC square wave voltage is resonantly boosted by the full-bridge power inverter circuit 3 in conjunction with the LLC resonant transformer circuit 4. Specifically, during the resonant boosting process, the switching frequency of the switching transistors within the full-bridge power inverter circuit 3 is adjusted by the control chip to boost or reduce the AC square wave voltage, thereby changing the voltage amplitude of the AC square wave voltage on the input side of the LLC resonant transformer circuit 4. This allows for the resonant boosting of the output voltage to a high-frequency AC power within the required output voltage range, while simultaneously achieving electrical isolation between the input and output sides of the LLC resonant transformer circuit 4. The converted high-frequency AC power is then rectified and smoothed by the rectifier and filter output circuit 5, ultimately converting it into stable DC power to supply the downstream load.

[0022] For further details, please review. Figure 1-2 The bus drive branch 21 includes a first power diode. First power MOSFET Second power diode and the second power MOSFET First power diode The anode is electrically connected to the positive terminal of DC power supply 1, and the first power diode... Cathode and first capacitor Electrical connection; first power MOSFET The drain of the first power MOSFET is electrically connected to the positive terminal of DC power supply 1. The source diode is electrically connected to the bus pre-charge control branch 23; the second power diode... The anode is electrically connected to the negative terminal of DC power supply 1, and the second power diode... The cathode is electrically connected to the bus pre-charge control branch 23; the second power MOSFET is also connected. The drain of the second power MOSFET is electrically connected to the negative terminal of DC power supply 1. Source and second capacitor Electrical connection; the control chip is connected to the first power MOSFET respectively. Gate and second power MOSFET Gate electrical connection.

[0023] Among them, the first power diode With the second power diode It can limit the current flow during charging of DC power supply 1, preventing reverse current from flowing back into DC power supply 1, thus achieving reverse protection for DC power supply 1. First power MOSFET With the second power MOSFET It can switch on and off in response to the PWM drive signal output by the control chip. When the first power MOSFET... It turns on when receiving a high-level drive signal and turns off when receiving a low-level drive signal, thus controlling the on / off state of the positive terminal of DC power supply 1 and the bus pre-charge control branch 23; when the second power MOSFET... It turns on when receiving a high-level drive signal and turns off when receiving a low-level drive signal, which can control the on / off state of the negative terminal of DC power supply 1 and the bus precharge control branch 23.

[0024] In this example, DC power supply 1 starts by outputting an initial DC voltage of a preset amplitude. After the control chip is powered on, it collects the DC power supply output voltage and the first capacitor value in real time. Terminal voltage, second capacitor Terminal voltage, at this time the first capacitor With the second capacitor It is in an unloaded state with no energy storage, i.e., the first capacitor. Terminal voltage and second capacitor The terminal voltage approaches 0, and the DC power supply output voltage is related to the first capacitor. Terminal voltage and second capacitor The voltage difference between the terminals is much greater than the preset voltage difference threshold. The control chip outputs a low-level regulation signal to control the bus pre-charge regulation branch 23 to be in the second state. At this time, the bus pre-charge regulation branch 23 is connected to the circuit, and the first power MOSFET... With the second power MOSFET Since there is no drive signal input to the gate, the first power MOSFET... With the second power MOSFET Maintaining the off state continuously completely disconnects DC power supply 1 through the first power diode. First power MOSFET Second power diode and the second power MOSFET The high-power path of the direct-through bus capacitor branch 22 eliminates the instantaneous inrush current at the source. At this time, the circuit relies solely on the first power diode. With the second power diode Due to its unidirectional conduction characteristic, the initial DC current is slowly converted to the first capacitor after being current-limited by the bus pre-charge control branch 23 connected to the circuit. With the second capacitor Charging, the bus pre-charge control branch 23 is connected to the circuit to make the first capacitor With the second capacitor Parallel connection, first capacitor after charging is complete Terminal voltage and second capacitor The terminal voltages all stabilize at the DC power supply output voltage. As the charging process continues, the first capacitor... Terminal voltage and second capacitor The terminal voltage gradually increases, and the output voltage of the DC power supply is related to the first capacitor. Terminal voltage and second capacitor The voltage difference between the terminals continues to decrease, when the DC power supply output voltage and the first capacitor... The voltage difference between the terminals is less than a preset voltage difference threshold, and the DC power supply output voltage is less than that of the second capacitor. When the voltage difference between the terminals is also less than the preset voltage difference threshold, the first capacitor... With the second capacitor Once charging and energy storage are complete, the control chip outputs a high-level control signal to put the bus pre-charge control branch 23 into its first state, thus bypassing the bus pre-charge control branch 23 and stopping the DC power supply 1 from supplying power to the first capacitor. With the second capacitor Charging, at this time the first capacitor With the second capacitor Series connection, first capacitor Terminal voltage and second capacitor The terminal voltages are all stable at half of the DC power supply output voltage. The control chip collects the data from the first capacitor after stabilization. Terminal voltage and second capacitor The sum of the terminal voltages is used to calculate the required output voltage of the LLC resonant transformer circuit 4. This required output voltage is then compared with the maximum reference output voltage corresponding to the LLC resonant transformer circuit 4. When the required output voltage is less than the maximum reference output voltage, the circuit is adapted to a low-voltage resonant condition, and is determined to be in the first resonant boost state. The control chip then controls the output of the first power MOSFET. The gate drive signal is a low-level signal, and the second power MOSFET... The gate drive signal is a high-level signal, which, together with the control bus pre-charge regulation branch 23 being in the first state, causes the first capacitor to... With the second capacitor A series voltage divider is used to adapt the low-voltage output demand with a single DC power supply output voltage; when the required output voltage is greater than or equal to the maximum reference output voltage, it adapts to the high-voltage rise resonance condition, and the control chip controls the bus pre-charge regulation branch 23 to be in the second state, while continuously sampling the first capacitor. Terminal voltage and second capacitor Terminal voltage, and determine the first capacitor. Terminal voltage and second capacitor The magnitude of the terminal voltage, when the first capacitor The terminal voltage is less than that of the second capacitor. When the terminal voltage is [value], it indicates the first capacitor. Energy storage is unstable, requiring adjustments to the first capacitor. During charging, the overall circuit is determined to be in the second resonant boost state, and the control chip controls the output of the first power MOSFET. Second power MOSFET The gate drive signals are all low-level signals, and the initial DC current flows through the first power diode. Second power diode The charging circuit, consisting of the bus pre-charge control branch 23 and the first capacitor, forms the first capacitor. Charging, while the first capacitor The terminal voltage is greater than or equal to that of the second capacitor. When the terminal voltage is [value], it indicates the second capacitor. Energy storage is unstable, requiring a second capacitor. During charging, the overall circuit is determined to be in the third resonant boost state, and the control chip controls the output of the first power MOSFET. Second power MOSFET The gate drive signals are all high-level signals, and the initial DC current flows through the first power MOSFET. Second power MOSFET And the bus pre-charge control branch 23 is the second capacitor. Charging causes the first capacitor to... With the second capacitor The parallel superposition of transistors creates double the DC power output voltage, expanding the voltage output range. This allows the first power MOSFET to be updated in real time according to the dynamic changes in the output voltage required by the LLC resonant transformer circuit 4. Second power MOSFET The drive signal adaptively switches between on and off states to ensure stable operation under all working conditions.

[0025] For further details, please review. Figure 1-2 The bus pre-charge control branch 23 includes a pre-charge resistor. and control switch Pre-charge resistor One end is connected to the first power MOSFET Source and second power diode Between cathodes, pre-charge resistance The other end is connected to the first capacitor. With the second capacitor Between; control switch With pre-charge resistance Parallel connection, control switch It is also electrically connected to the control chip.

[0026] Among them, the pre-charge resistor A control switch used to limit the current flowing into the bus capacitor branch 22. The on / off state is determined by the control chip based on the DC power supply output voltage and the first capacitor. Terminal voltage and second capacitor The voltage difference determination result between the terminals directly determines the pre-charge resistance. Whether the circuit is connected and working.

[0027] In this example, when the DC power supply output voltage is related to the first capacitor... The voltage difference between the terminals is greater than or equal to a preset voltage difference threshold, or the DC power supply output voltage is greater than or equal to the voltage difference between the terminals and the second capacitor. When the voltage difference between the terminals is greater than or equal to a preset voltage difference threshold, the control chip outputs a low-level control signal to control the control switch. In the second state, i.e., the control switch Disconnection causes the pre-charge resistor to... The initial DC power output from DC power supply 1 is connected to the circuit and passes through the pre-charge resistor. After current limiting, it becomes the first capacitor. Second capacitor Charging significantly reduces the inrush current at power-on, preventing damage to capacitors and power devices due to overcurrent stress and achieving a smooth charging effect. When the DC power supply output voltage is equal to that of the first capacitor... The voltage difference between the terminals is less than a preset voltage difference threshold, and the DC power supply output voltage is less than that of the second capacitor. When the voltage difference between the terminals is also less than the preset voltage difference threshold, the first capacitor is determined to be... Second capacitor Once charging is complete, the control chip outputs a high-level control signal to control the control switch. In the first state, i.e., the control switch Close, directly apply the pre-charge resistor Bypass, pre-charge resistor It exits the working state and has no power loss.

[0028] For further details, please review. Figure 1 The full-bridge power inverter circuit 3 includes a third power MOSFET. Fourth power MOSFET Fifth power MOSFET and the sixth power MOSFET Third power MOSFET Drain and first capacitor Electrical connection, third power MOSFET Source and fourth power MOSFET Drain connection, fourth power MOSFET Source and second capacitor Electrical connection, fifth power MOSFET Drain and third power MOSFET Drain connection, fifth power MOSFET Source and sixth power MOSFET Drain connection, sixth power MOSFET Source and fourth power MOSFET Source electrical connection; control chip is connected to the third power MOSFET respectively. Gate, fourth power MOSFET Gate, fifth power MOSFET Gate and sixth power MOSFET Gate electrical connection.

[0029] Among them, the third power MOSFET Fourth power MOSFET Fifth power MOSFET and the sixth power MOSFET The PWM drive signal output from the receiving control chip enables alternating on and off of the transistor, eliminating signal delay and false triggering. (Third power MOSFET) Fourth power MOSFET Fifth power MOSFET and the sixth power MOSFET The first capacitor receives the DC bus voltage output from the bus voltage regulation circuit 2. Terminal voltage and second capacitor The sum of the terminal voltages, passing through the third power MOSFET in the diagonal direction. Sixth power MOSFET and the fourth power MOSFET Fifth power MOSFET The synchronous alternating conduction converts the DC bus voltage into an AC square wave voltage, providing a stable AC input source for the subsequent LLC resonant transformer circuit 4.

[0030] In this example, after the control chip powers on, it outputs complementary PWM drive signals to control the third power MOSFET. With the sixth power MOSFET Synchronous conduction, fourth power MOSFET With the fifth power MOSFET Synchronous conduction, with two sets of switching transistors periodically alternating, when the third power MOSFET... Sixth power MOSFET Turn on, fourth power MOSFET Fifth power MOSFET When turned off, the DC bus voltage output by the bus voltage regulation circuit 2 is applied in the positive direction to the LLC resonant transformer circuit 4; when the third power MOSFET... Sixth power MOSFET Turn off, fourth power MOSFET Fifth power MOSFET When turned on, the DC bus voltage output by the bus voltage regulation circuit 2 is applied negatively to the LLC resonant transformer circuit 4, thereby forming a continuous and symmetrical AC square wave voltage. Simultaneously, the third power MOSFET... Fourth power MOSFET Fifth power MOSFET and the sixth power MOSFET The switching frequency can be dynamically adjusted by the control chip, in conjunction with the first capacitor. With the second capacitor Switching the connection method enables dual regulation of the voltage amplitude and frequency on the input side of the LLC resonant transformer circuit 4, providing a core foundation for subsequent ultra-wide range voltage boost regulation.

[0031] For further details, please review. Figure 1 The LLC resonant transformer circuit 4 includes a resonant inductor. Resonant capacitor and high frequency transformers Resonant inductor With resonant capacitor A resonant cavity is formed, with one end of the resonant cavity connected to a third power MOSFET. With the fourth power MOSFET Between them, the other end is connected to the fifth power MOSFET. With the sixth power MOSFET Between; high-frequency transformer The primary side is connected to the resonant inductor. With resonant capacitor Between, high-frequency transformer The secondary side is connected to the rectifier filter output circuit 5.

[0032] Among them, resonant inductor With resonant capacitor By forming a resonant cavity, the gain of the AC square wave voltage can be adjusted through the resonance effect, reducing the power consumption of the third-generation MOSFET. Fourth power MOSFET Fifth power MOSFET and the sixth power MOSFET Reduce switching losses and improve overall conversion efficiency; high-frequency transformer It combines electrical isolation and voltage ratio regulation, enabling electrical isolation between the primary high-voltage side and the secondary low-voltage load side, while also working with the resonant cavity to boost and transform the voltage amplitude.

[0033] In this example, the AC square wave voltage output from the full-bridge power inverter circuit 3 is directly input to the resonant cavity, and the resonant inductor... With resonant capacitor High-frequency resonance is generated, and the third power MOSFET is changed by the control chip. Sixth power MOSFET Or the fourth power MOSFET Fifth power MOSFET By adjusting the ratio of the switching frequency to the corresponding resonant frequency of the resonant cavity, the voltage gain of the resonant cavity can be continuously adjusted, thereby outputting a high-frequency AC voltage. High-frequency transformer. The high-frequency AC voltage after resonance is acquired, and the voltage is converted into high-frequency AC power through a preset turns ratio. The high-frequency AC power after primary-side resonance transformation is transmitted to the secondary side. Combined with the bus DC voltage regulation logic of bus voltage regulation circuit 2, when the bus DC voltage output is single-times the DC power output voltage, the resonant cavity input amplitude is an AC square wave of single-times the DC power output voltage; when the bus DC voltage output is double-times the DC power output voltage, the resonant cavity input amplitude is an AC square wave of double-times the DC power output voltage, thereby realizing the corresponding ultra-wide range of voltage output.

[0034] For further details, please review. Figure 1 And refer to them together Figure 3 , Figure 3 for Figure 1 A schematic diagram of the topology of the rectifier and filter output circuit. The rectifier and filter output circuit 5 includes a rectifier freewheeling branch 51 and a DC filter branch 52; the rectifier freewheeling branch 51 and the high-frequency transformer... The secondary side is electrically connected; the DC filter branch 52 is connected in parallel with the rectifier freewheeling branch 51.

[0035] Among them, the rectifier freewheeling branch 51 can convert the high-frequency transformer The high-frequency AC output from the secondary side is converted into unidirectional pulsating DC, and also has a freewheeling function to avoid voltage interruptions and current surges during AC commutation, ensuring continuous and stable output current. The DC filter branch 52 can smooth and filter the rectified unidirectional pulsating DC, filtering out voltage pulsation components and high-frequency noise, and converting the unidirectional pulsating current into stable DC to meet the stable power supply requirements of the downstream load.

[0036] In this example, the rectifier freewheeling branch 51 includes a first rectifier diode. Second rectifier diode Third rectifier diode Fourth rectifier diode Compatible with high frequency transformers Secondary-side high-frequency AC output characteristics. Specifically, the first rectifier diode... Anode and High Frequency Transformer The secondary winding's corresponding terminals are electrically connected, and the first rectifier diode is... The cathodes are respectively connected to the third rectifier diode. The cathode and the input terminal of the DC filter branch 52 are electrically connected; the second rectifier diode... Cathode and High Frequency Transformer The secondary winding's corresponding terminals are electrically connected, and the second rectifier diode is... The anodes are respectively connected to the fourth rectifier diode. Anode, DC filter branch 52 ground terminal electrical connection; third rectifier diode Anode and High Frequency Transformer Electrical connection of the non-identical terminals of the secondary winding; fourth rectifier diode Cathode and High Frequency Transformer The non-identical terminals of the secondary winding are electrically connected. Among them, the high-frequency transformer... The high-frequency AC output from the secondary side exhibits alternating positive and negative voltage half-cycles. When the high-frequency transformer... When the secondary winding is in the positive half-cycle, the high-frequency transformer The secondary winding's corresponding terminal potential is higher than the non-corresponding terminal potential, and the current flows out through the first rectifier diode. The forward bias current is supplied to the input terminal of the DC filter branch 52, filtered, and then returned through the equivalent load and ground terminal, and finally through the fourth rectifier diode. Forward bias conduction current return to high frequency transformer The non-corresponding terminals of the secondary winding form a positive current loop; when the high-frequency transformer... When the secondary winding is in the negative half-cycle, the high-frequency transformer The potential at the non-corresponding terminal of the secondary winding is higher than that at the corresponding terminal, at which point the second rectifier diode... Third rectifier diode The first rectifier diode conducts under forward voltage drop. Fourth rectifier diode Cut off due to reverse voltage drop; current supplied by high-frequency transformer. The current flows out from the non-identical terminal of the secondary winding and passes through the third rectifier diode. The forward bias current is supplied to the input terminal of the DC filter branch 52, filtered, and then returned through the equivalent load and ground terminal, and finally through the second rectifier diode. Forward bias conduction current return to high frequency transformer The secondary winding's corresponding terminals form a reverse current loop. Through the above time-sharing conduction logic, regardless of whether the high-frequency AC is in the positive or negative half-cycle, the rectifier freewheeling branch 51 always converts the bidirectional high-frequency AC into a unidirectional pulsating DC with consistent direction and unchanged polarity. The high-frequency AC is converted into a unidirectional pulsating DC with amplitude fluctuating slightly with the high-frequency cycle. Simultaneously, during the brief interval of zero-crossing commutation of the high-frequency AC, the diodes in the rectifier freewheeling branch 51 can form a freewheeling loop, preventing output current interruption and voltage jumps, effectively suppressing voltage gaps and current surges, and providing a regular pre-voltage waveform for the smooth filtering process of the subsequent DC filter branch 52.

[0037] Furthermore, the DC filter branch 52 includes a filter capacitor. and equivalent load ; Filter capacitor Connected in parallel with rectifier freewheeling branch 51; equivalent load With filter capacitor in parallel.

[0038] Among them, high-frequency transformers The high-frequency AC output from the secondary side is rectified by the rectifier-freewheeling branch 51 to generate a unidirectional pulsating DC with a small amplitude ripple. The filter capacitor... It can utilize its own charging and discharging characteristics to absorb voltage peaks, fill voltage valleys, and filter out high-frequency pulse components and harmonic interference in unidirectional pulsating DC current, thus achieving voltage smoothing. Equivalent load The external working load at the back end of the converter is connected in parallel to the filter capacitor. Both ends can stably obtain rectified and filtered DC power, ensuring continuous and stable operation of the load.

[0039] Example 2 Please review Figure 1-3 And refer to them together Figure 4 , Figure 4 This is a schematic diagram of the control flow of the voltage-raised LLC resonant converter in the embodiment. The present invention also provides a control method for a voltage-raised LLC resonant converter, which is applied to the voltage-raised LLC resonant converter described in Embodiment 1, and includes the following steps: S01: DC power supply 1 is the first capacitor and the second capacitor During charging, the control chip detects the DC power supply output voltage. Voltage at the first capacitor terminal and the voltage at the second capacitor terminal and calculate and and The difference and , and then and Compared with the preset differential pressure threshold Compare; In this embodiment of the invention, after the DC power supply 1 is powered on, it continuously outputs an initial DC current of a preset amplitude, which is the first capacitor in the bus capacitor branch 22. Second capacitor It provides charging power and a stable auxiliary power supply to the control chip, enabling the control chip to continuously acquire circuit electrical parameters and output drive signals. The control chip relies on its own voltage acquisition port on the first capacitor. and the second capacitor During charging, the DC power supply output voltage is collected in real time. Voltage at the first capacitor terminal and the voltage at the second capacitor terminal The real-time analog voltage signal is used to perform difference calculation through the built-in arithmetic circuit to obtain the following results: and voltage difference , and voltage difference Retrieve internal preset differential pressure threshold Complete the item-by-item comparison to determine the current first capacitor. and the second capacitor The charging conditions provide an electrical basis for the subsequent state switching of the bus pre-charging control branch 23.

[0040] S02: If < and < The control chip controls the bus precharge regulation branch 23 to be in the first state, so that the first capacitor With the second capacitor In series, DC power supply 1 stops supplying power to the first capacitor. and the second capacitor If charging is not enabled, the control chip controls the bus pre-charge regulation branch 23 to be in the second state, causing the first capacitor to... With the second capacitor In parallel connection, when the first capacitor With the second capacitor When connected in parallel, DC power supply 1 continues to supply power to the first capacitor. and the second capacitor Charge until satisfied. < and < Subsequently, the control chip controls the bus pre-charge regulation branch 23 to be in the first state, causing the first capacitor to... With the second capacitor In series, DC power supply 1 stops supplying power to the first capacitor. With the second capacitor Charge; In this embodiment of the invention, the control chip dynamically switches between two operating states of the bus pre-charge control branch 23 based on the voltage difference determination result, thereby realizing the first capacitor Second capacitor Series-parallel topology switching and charging start / stop control: when the differential voltage reaches the target, switch the series topology and stop charging the first capacitor. With the second capacitor During charging, if the differential voltage does not meet the standard, the parallel topology maintains continuous current-limited charging. < and < At that time, the first capacitor With the second capacitor Once charging is complete, the control chip outputs a high-level control signal to put the bus pre-charge control branch 23 into its first state, causing the first capacitor... With the second capacitor In series, the bus pre-charge control branch 23 is bypassed, and the first capacitor... With the second capacitor Divide the DC power supply output voltage This ensures that the voltage at both terminals is stabilized at DC power supply 1 terminates the first capacitor With the second capacitor Charging operation. When or Any value greater than or equal to When, determine the first capacitor Or the second capacitor Insufficient energy storage and substandard terminal voltage cause the control chip to output a low-level regulation signal, controlling the bus pre-charge regulation branch 23 to enter the second state. At this time, the bus pre-charge regulation branch 23 is connected to the circuit, reconstructing the circuit topology so that the first capacitor... With the second capacitor Parallel connection, and the first capacitor With the second capacitor When connected in parallel, DC power supply 1 continues to supply power to the first capacitor via bus pre-charge control branch 23. With the second capacitor Slow charging, at this time the first capacitor With the second capacitor After being connected in parallel to the two ends of DC power supply 1, the voltages at both ends stabilize after charging. The control chip cyclically executes the voltage acquisition, difference calculation, and threshold comparison process until the condition is met. < and < Subsequently, the control chip switches the bus pre-charge regulation branch 23 back to the first state, and the DC power supply 1 stops supplying power to the first capacitor. With the second capacitor Charge.

[0041] S03: The bus pre-charge control branch is in the first or second state, and the voltage at the first capacitor terminal is... With the voltage at the second capacitor terminal After stabilization, the control chip adjusts the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum Calculate the required output voltage for the LLC resonant transformer circuit. ; Obtain the maximum output voltage conversion ratio corresponding to the LLC resonant transformer circuit and calculate , and then With output voltage Perform a comparison and generate comparison results; In this embodiment of the invention, regardless of whether the bus pre-charge control branch 23 is in the first state or the second state, the control chip continuously accumulates the voltage at the first capacitor terminal during steady-state operation. With the voltage at the second capacitor terminal The DC bus voltage flowing into the input terminal of the full-bridge power inverter circuit 3 is obtained. Based on the resonant cavity topology, high-frequency transformer turns ratio, and power device parameters of LLC resonant transformer circuit 4, the required output voltage for the downstream load side, i.e., LLC resonant transformer circuit 4, can be calculated. The specific calculation process is as follows: ; ; ; ; In the formula, For high frequency transformers The number of turns ratio, For switching frequency, For high frequency transformers The resonant frequency, It is the ratio between the switching frequency and the resonant frequency. It is a resonant inductor. It is a resonant capacitor. For quality factor, For high frequency transformers The equivalent load connected to the secondary side, For high frequency transformers The primary magnetizing inductance, The inductance ratio between the excitation inductance and the resonant inductance is calculated by combining the excitation characteristics of the LLC resonant transformer circuit 4, the resonant cavity parameters, the load conditions, and the transformer turns ratio. This model can be adapted to solve for the output voltage under different bus DC voltages, different switching frequencies, and different load conditions. Furthermore, the maximum output voltage conversion ratio is determined based on the ideal state of the transformer inside the LLC resonant transformer circuit 4. The ideal state refers to the high-frequency transformer inside the LLC resonant transformer circuit 4. Operating at switching frequency equal to the resonant frequency When the series resonant point is reached, that is... Under lossless, light-load, and ideal transformer conditions, the maximum output voltage conversion ratio calculated using the above formula is: Then, the maximum reference output voltage is obtained through numerical calculation. The real-time output voltage With maximum reference output voltage Perform numerical comparisons and generate comparison results, including and , that is At that time, the first capacitor With the second capacitor In series and the DC voltage of the bus is It is compatible with low-voltage output range; At that time, the first capacitor With the second capacitor In parallel connection and the DC voltage of the bus is It is compatible with high voltage output range. The control chip distinguishes between two resonant working modes by comparing voltage values, providing a basis for determining the output of the internal power tube drive signal of the bus drive branch 21.

[0042] S04: Based on the comparison result, the control chip controls the bus pre-charge regulation branch 23 to be in the first state or the second state, and controls the on / off state of the bus drive branch 21 to change the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum Simultaneously, inversion and resonant boosting conversion are performed through the full-bridge power inverter circuit 3 and the LLC resonant transformer circuit 4 to resonantly boost the output voltage. The output range generates high-frequency alternating current and outputs it to the rectifier and filter output circuit 5; In this embodiment of the invention, when the control chip determines the comparison result is... When the voltage reaches low-voltage resonant operating condition, the voltage at the first capacitor terminal is... With the voltage at the second capacitor terminal The voltage needs to be stabilized at half of the DC power supply output voltage. The control chip controls the bus precharge regulation branch 23 to be in the first state, so that the bus precharge regulation branch 23 is bypassed. The control chip also controls the first power MOSFET inside the bus drive branch 21. The drive signal is a low-level signal, and the second power MOSFET... The drive signal is a high-level signal to turn off the first power MOSFET. Turn on the second power MOSFET With the bus pre-charge control branch 23 being bypassed, the first capacitor... With the second capacitor Stable series voltage divider, while controlling the third power MOSFET inside the full-bridge power inverter circuit 3. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction forms an amplitude of The AC square wave input LLC resonant transformer circuit 4 is adapted to the low-voltage output range. When the control chip determines the comparison result is... At this time, it enters the high-voltage rise resonance condition, at which point the voltage at the first capacitor terminal is... With the voltage at the second capacitor terminal To stabilize the DC power supply output voltage, the control chip controls the bus pre-charge regulation branch 23 to be in the second state, connecting the bus pre-charge regulation branch 23 to the circuit. Then, the control chip continuously monitors and samples the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal And determine the magnitude of the voltage across the two ends. When the voltage across the first capacitor... Less than the voltage at the second capacitor terminal When, it indicates the first capacitor Insufficient energy storage; the control chip controls the first power MOSFET inside the bus drive branch 21. With the second power MOSFET All drive signals are low-level signals, and the bus pre-charge control branch 23 connected to the circuit is the first capacitor. Charging causes the first capacitor to... With the second capacitor Connect in parallel and raise its bus DC voltage to When the voltage at the first capacitor terminal The voltage at the second capacitor terminal is greater than or equal to the voltage at the second capacitor terminal. When, it indicates the second capacitor Insufficient energy storage; the control chip controls the first power MOSFET inside the bus drive branch 21. With the second power MOSFET All drive signals are high-level signals, and the bus pre-charge control branch 23 connected to the circuit is the second capacitor. Charging also makes the first capacitor With the second capacitor Connect in parallel and raise its bus DC voltage to Simultaneously, it controls the third power MOSFET inside the full-bridge power inverter circuit 3. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction forms an amplitude of The AC square wave input LLC resonant transformer circuit 4 is adapted to the high-voltage output range. In actual operation, the voltage gain is continuously adjusted by regulating the switching frequency of the power transistors inside the full-bridge power inverter circuit 3, thereby expanding the output voltage range from... Expand to This transforms and generates high-frequency alternating current, which is then output to the rectifier and filter output circuit 5.

[0043] S05: Rectifier and filter output circuit 5 rectifies and smooths the high-frequency AC power to generate DC power.

[0044] In this embodiment of the invention, the rectifier-filter output circuit 5 includes a rectifier-freewheeling branch 51 and a DC filter branch 52. The rectifier-freewheeling branch 51 receives the converted high-frequency AC power and completes the voltage rectification and conversion by time-division multiplexing of the positive and negative half-cycles. That is, during the positive half-cycle, the first rectifier diode... Fourth rectifier diode Forward bias conduction, second rectifier diode Third rectifier diode Reverse bias cutoff; second rectifier diode during negative half-cycle Third rectifier diode Forward bias conduction, first rectifier diode Fourth rectifier diode The negative bias cutoff ensures that the high-frequency AC current can be regulated into unidirectional pulsating DC current during both the positive and negative half-cycles. Simultaneously, the freewheeling characteristics of the corresponding rectifier diodes are utilized to prevent voltage zero-crossing interruptions and current surges. The rectified unidirectional pulsating DC current is input to the DC filter branch 52, which relies on a filter capacitor. With equivalent load Parallel structure, filter capacitor By absorbing voltage peaks and compensating for voltage troughs through charging and discharging characteristics, and filtering out high-frequency pulsating noise and harmonic interference, the final output is a stable DC power supply with a smooth waveform and stable amplitude, continuously supplying the equivalent load at the downstream end. Provides a stable power supply.

[0045] For further details, please review. Figure 1-4 And refer to them together Figure 5-7 , Figure 5 This is a schematic diagram of the circuit operation of the voltage-boosting LLC resonant converter in the first resonant boost state in the embodiment; Figure 6 This is a schematic diagram of the circuit operation of the voltage-boosting LLC resonant converter in the second resonant boost state in the embodiment; Figure 7 This is a schematic diagram illustrating the circuit operation of the voltage-boosting LLC resonant converter in the third resonant boost state in this embodiment. The inversion and resonant boost conversion via the full-bridge power inverter circuit and LLC resonant transformer circuit in this embodiment includes the following steps: The control chip comparison result is as follows When needed, the control chip controls the regulating switch. In the first state, the pre-charge resistor is... Bypassed and controlling the first power MOSFET The drive signal is a low-level signal, and the second power MOSFET... The drive signal is a high-level signal to turn off the first power MOSFET. Turn on the second power MOSFET Simultaneously drive the third power MOSFETs Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction brings the entire circuit to the first resonant boost state, and lowers the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum The inverter generates an AC square wave voltage; the control chip adjusts the third power MOSFET in the first resonant boost state. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET The switching frequency is adjusted to control the voltage amplitude of the AC square wave voltage, which is then passed through a high-frequency transformer. The adjusted AC square wave voltage is resonantly boosted to raise the output voltage. The output range is ; In this embodiment of the invention, the control chip completes the output voltage. With maximum reference output voltage After comparison, determine At that time, the control chip outputs a high-level control signal to drive the control switch inside the bus pre-charge control branch 23. Switch to the first state, i.e., the control switch. It is in a closed state, and is in harmony with the control switch. Parallel pre-charge resistors Directly bypassed, pre-charge resistance The circuit is disconnected from its operating loop, resulting in no power loss within the loop. The control chip synchronously outputs a constant drive level to manage the power devices inside the bus drive branch 21, continuously supplying power to the first power MOSFET. The gate delivers a low-level drive signal, and the first power MOSFET... Maintaining a stable off state while continuously supplying power to the second power MOSFET The gate delivers a high-level drive signal, and the second power MOSFET... To maintain a stable conduction state, the circuit matching is as follows: Figure 5 The switching mode shown makes the first capacitor... With the second capacitor Series connection, first capacitor With the second capacitor Divide the DC power supply output voltage First capacitor Or the second capacitor Stable and maintained at The control chip continuously outputs complementary alternating drive signals to the full-bridge power inverter circuit 3, driving the third power MOSFET. Sixth power MOSFET Synchronous conduction and the fourth power MOSFET Fifth power MOSFET Synchronous shutdown, and the fourth power MOSFET Fifth power MOSFET Synchronous conduction and third power MOSFET Sixth power MOSFET The periodic alternation of synchronous turn-off keeps the entire circuit in the first resonant boost state, and the voltage at the first capacitor terminal of the input LLC resonant transformer circuit 4 is adjusted accordingly. With the voltage at the second capacitor terminal sum Perform an inverting process to generate an amplitude equal to The AC square wave voltage. The control chip adjusts the third power MOSFET during the first resonant boost state. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET The switching frequency is adjusted to control the resonant inductance inside the resonant cavity. With resonant capacitor The resonant gain characteristics are determined, and the voltage amplitude of the AC square wave voltage is adjusted, and then passed through a high-frequency transformer. A resonant boost transformation is performed to obtain the output range as follows: Output voltage This enables continuous steady-state operation in the first resonant lifting state.

[0046] The control chip comparison result is as follows When needed, the control chip controls the regulating switch. In the second state, the pre-charge resistor is... The circuit is connected to the circuit, and the voltage at the first capacitor terminal is continuously sampled. and the voltage at the second capacitor terminal Then the voltage at the first capacitor terminal With the voltage at the second capacitor terminal To make a comparison, if The control chip controls the first power MOSFET. With the second power MOSFET The drive signal is a low-level signal to turn off the first power MOSFET. With the second power MOSFET Simultaneously drive the third power MOSFETs Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction causes the entire circuit to be in a second resonant boost state, and also lowers the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum Inverting to generate AC square wave voltage; if Then control the first power MOSFET With the second power MOSFET The drive signal is a high-level signal to turn on the first power MOSFET. With the second power MOSFET Then drive the third power MOSFET respectively. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction brings the entire circuit to the third resonant boost state, and also lowers the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum The inverter generates an AC square wave voltage; the control chip adjusts the third power MOSFET in the second or third resonant boost state. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET The switching frequency is adjusted to control the voltage amplitude of the AC square wave voltage, which is then passed through a high-frequency transformer. The adjusted AC square wave voltage is resonantly boosted to raise the output voltage. The output range is .

[0047] In this embodiment of the invention, the control chip determines... When the circuit switches to high-voltage boost resonance mode, the voltage at the first capacitor terminal... With the voltage at the second capacitor terminal The output voltage needs to be stabilized at the DC power supply. The control chip controls the output of a low-level regulation signal to drive the regulation switch inside the bus pre-charge regulation branch 23. Switch to the second state, i.e., the control switch. The pre-charge resistor is in an open state. The circuit is connected, and then the control chip continuously samples the voltage at the first capacitor terminal. and the voltage at the second capacitor terminal And complete real-time numerical comparison. Detected. The value is less than When the value is displayed, the control chip sends a signal to the first power MOSFET. With the second power MOSFET The gate synchronously outputs a low-level drive signal, causing the first power MOSFET to... With the second power MOSFET Synchronous shutdown, circuit matching, etc. Figure 6 The switching mode is shown. The full-bridge power inverter circuit 3 maintains the predetermined alternating conduction logic, and the third power MOSFET... Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET The periodic alternating switching on and off of the circuit puts the entire circuit into a second resonant boost state, generating an amplitude of [value missing] at the input terminal of the LLC resonant transformer circuit 4. The AC square wave voltage synchronously completes the first capacitor Voltage replenishment and stabilization operation. Detected. The value is greater than or equal to When the value is displayed, the control chip sends a signal to the first power MOSFET. With the second power MOSFET The gate synchronously outputs a high-level drive signal, and the first power MOSFET... With the second power MOSFET Synchronous conduction, the circuit switches to such Figure 7 The corresponding switching mode, the third power MOSFET Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Periodically alternating on and off and maintaining The amplitude of the AC square wave voltage puts the entire circuit in the third resonant boost state, completing the second capacitor. The voltage is replenished and stabilized. It alternates between the second and third resonant rise states, dynamically balancing the first capacitor. With the second capacitor The terminal voltage is maintained at a stable level. By continuously adjusting the third power MOSFET Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET The switching frequency changes the resonant gain, thus affecting the high-frequency transformer. Output voltage Expand to The ultra-wide range enables stable output under high-voltage resonant lifting conditions.

[0048] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A voltage-boosting LLC resonant converter, characterized in that, include: Control chip; A DC power supply, which is electrically connected to the control chip; The bus voltage regulation circuit includes a bus drive branch, a bus capacitor branch, and a bus pre-charge regulation branch; the bus drive branch is electrically connected to the DC power supply; the bus capacitor branch includes a first capacitor. and the second capacitor The first capacitor With the second capacitor Electrical connection, the first capacitor and the second capacitor They are also electrically connected to the bus drive branch respectively; One end of the bus pre-charge control branch is connected to the bus drive branch, and the other end is connected to the second capacitor. Electrical connection; the control chip is connected to the bus drive branch and the first capacitor respectively. Second capacitor and the electrical connection of the busbar pre-charge control branch; A full-bridge power inverter circuit, wherein the full-bridge power inverter circuit is connected to the control chip and the first capacitor respectively. and the second capacitor Electrical connection; LLC resonant transformer circuit, wherein the LLC resonant transformer circuit is electrically connected to the full-bridge power inverter circuit; A rectifier and filter output circuit is electrically connected to the LLC resonant transformer circuit.

2. The voltage-boosting LLC resonant converter according to claim 1, characterized in that, The bus drive branch includes a first power diode. First power MOSFET Second power diode and the second power MOSFET The first power diode The anode is electrically connected to the positive terminal of the DC power supply, and the first power diode... cathode and the first capacitor Electrical connection; the first power MOSFET The drain of the first power MOSFET is electrically connected to the positive terminal of the DC power supply. The source is electrically connected to the bus pre-charge control branch; the second power diode The anode is electrically connected to the negative terminal of the DC power supply, and the second power diode... The cathode is electrically connected to the bus pre-charge control branch; the second power MOSFET The drain of the second power MOSFET is electrically connected to the negative terminal of the DC power supply. Source and the second capacitor Electrical connection; the control chip is respectively connected to the first power MOSFET. Gate and the second power MOSFET Gate electrical connection.

3. The voltage-boosting LLC resonant converter according to claim 2, characterized in that, The bus pre-charge control branch includes a pre-charge resistor. and control switch The pre-charge resistor One end is connected to the first power MOSFET Source and the second power diode Between the cathodes, the pre-charge resistor The other end is connected to the first capacitor. With the second capacitor Between; the control switch With the pre-charge resistor Parallel connection, the control switch It is also electrically connected to the control chip.

4. The voltage-boosting LLC resonant converter according to claim 1, characterized in that, The full-bridge power inverter circuit includes a third power MOSFET. Fourth power MOSFET Fifth power MOSFET and the sixth power MOSFET The third power MOSFET Drain and the first capacitor Electrical connection, the third power MOSFET Source and the fourth power MOSFET The drain is electrically connected, and the fourth power MOSFET is... Source and the second capacitor Electrical connection, the fifth power MOSFET Drain and the third power MOSFET The drain is electrically connected, and the fifth power MOSFET is... Source and the sixth power MOSFET The drain is electrically connected, and the sixth power MOSFET is... Source and the fourth power MOSFET The source is electrically connected; the control chip is respectively connected to the third power MOSFET. Gate, fourth power MOSFET Gate, fifth power MOSFET Gate and sixth power MOSFET Gate electrical connection.

5. The voltage-boosting LLC resonant converter according to claim 4, characterized in that, The LLC resonant transformer circuit includes a resonant inductor. Resonant capacitor and high frequency transformers The resonant inductor With resonant capacitor A resonant cavity is formed, one end of which is connected to the third power MOSFET. With the fourth power MOSFET Between, the other end is connected to the fifth power MOSFET. With the sixth power MOSFET Between; the high-frequency transformer The primary side is connected to the resonant inductor. With resonant capacitor Between, the high-frequency transformer The secondary side is connected to the rectifier filter output circuit.

6. The voltage-boosting LLC resonant converter according to claim 5, characterized in that, The rectifier and filter output circuit includes a rectifier freewheeling branch and a DC filter branch; the rectifier freewheeling branch is connected to the high-frequency transformer. The secondary side is electrically connected; the DC filter branch is connected in parallel with the rectifier freewheeling branch.

7. The voltage-boosting LLC resonant converter according to claim 6, characterized in that, The DC filter branch includes a filter capacitor. and equivalent load The filter capacitor Connected in parallel with the rectifier freewheeling branch; the equivalent load With the filter capacitor in parallel.

8. A control method for a voltage-boosting LLC resonant converter, characterized in that, The method, applied to the voltage-boosting LLC resonant converter as described in any one of claims 1-7, includes the following steps: S01: DC power supply is the first capacitor. and the second capacitor During charging, the control chip detects the DC power supply output voltage. Voltage at the first capacitor terminal and the voltage at the second capacitor terminal and calculate and and The difference and , and then and Compared with the preset differential pressure threshold Compare; S02: If < and < The control chip controls the bus pre-charge regulation branch to be in the first state, causing the first capacitor to... With the second capacitor In series, the DC power supply stops supplying power to the first capacitor. With the second capacitor Charging; if not, the control chip controls the bus pre-charge regulation branch to be in the second state, causing the first capacitor to... With the second capacitor In parallel connection, when the first capacitor With the second capacitor When connected in parallel, the DC power supply continues to supply power to the first capacitor. and the second capacitor Charge until satisfied. < and < Subsequently, the control chip controls the bus pre-charge regulation branch to be in the first state, causing the first capacitor to... With the second capacitor In series, the DC power supply stops supplying power to the first capacitor. With the second capacitor Charge; S03: The bus pre-charge control branch is in the first or second state, and the voltage at the first capacitor terminal is... With the voltage at the second capacitor terminal After stabilization, the control chip adjusts the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum Calculate the required output voltage for the LLC resonant transformer circuit. ; Obtain the maximum output voltage conversion ratio corresponding to the LLC resonant transformer circuit and calculate , and then With output voltage Perform a comparison and generate comparison results; S04: The control chip controls the bus pre-charge regulation branch to be in the first or second state based on the comparison result, and controls the on / off state of the bus drive branch to change the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum Simultaneously, inversion and resonant boosting conversion are performed through a full-bridge power inverter circuit and an LLC resonant transformer circuit to resonantly boost the output voltage. The output range generates high-frequency alternating current and outputs it to the rectifier and filter output circuit; S05: The rectifier and filter output circuit rectifies and smooths the high-frequency AC power to generate DC power.

9. The control method for the voltage-boosting LLC resonant converter according to claim 8, characterized in that, The voltage at the first capacitor terminal With the voltage at the second capacitor terminal sum Calculate the required output voltage for the LLC resonant transformer circuit. The calculation process is as follows: ； ； ； ； ； In the formula, For high frequency transformers The number of turns ratio, For switching frequency, For high frequency transformers The resonant frequency, It is the ratio between the switching frequency and the resonant frequency. It is a resonant inductor. It is a resonant capacitor. For quality factor, For high frequency transformers The equivalent load connected to the secondary side, For high frequency transformers The primary magnetizing inductance, This is the inductance ratio between the magnetizing inductance and the resonant inductance.

10. The control method for the voltage-boosting LLC resonant converter according to claim 8, characterized in that, The inversion and resonant boost conversion via a full-bridge power inverter circuit and an LLC resonant transformer circuit includes the following steps: The control chip comparison result is as follows When needed, the control chip controls the regulating switch. In the first state, the pre-charge resistor is... Bypassed and controlling the first power MOSFET The drive signal is a low-level signal, and the second power MOSFET... The drive signal is a high-level signal to turn off the first power MOSFET. Turn on the second power MOSFET Simultaneously drive the third power MOSFETs Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction brings the entire circuit to the first resonant boost state, and lowers the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum The inverter generates an AC square wave voltage; the control chip adjusts the third power MOSFET in the first resonant boost state. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET The switching frequency is adjusted to control the voltage amplitude of the AC square wave voltage, which is then passed through a high-frequency transformer. The adjusted AC square wave voltage is resonantly boosted to raise the output voltage. The output range is ; The control chip comparison result is as follows When needed, the control chip controls the regulating switch. In the second state, the pre-charge resistor is... The circuit is connected to the circuit, and the voltage at the first capacitor terminal is continuously sampled. and the voltage at the second capacitor terminal Then the voltage at the first capacitor terminal With the voltage at the second capacitor terminal To make a comparison, if The control chip controls the first power MOSFET. With the second power MOSFET The drive signal is a low-level signal to turn off the first power MOSFET. With the second power MOSFET Simultaneously drive the third power MOSFETs Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction causes the entire circuit to be in a second resonant boost state, and also lowers the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum Inverting to generate AC square wave voltage; if Then control the first power MOSFET With the second power MOSFET The drive signal is a high-level signal to turn on the first power MOSFET. With the second power MOSFET Then drive the third power MOSFET respectively. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET Alternating conduction brings the entire circuit to the third resonant boost state, and also lowers the voltage at the first capacitor terminal. With the voltage at the second capacitor terminal sum The inverter generates an AC square wave voltage; the control chip adjusts the third power MOSFET in the second or third resonant boost state. Sixth power MOSFET With the fourth power MOSFET Fifth power MOSFET The switching frequency is adjusted to control the voltage amplitude of the AC square wave voltage, which is then passed through a high-frequency transformer. The adjusted AC square wave voltage is resonantly boosted to raise the output voltage. The output range is 。

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