LLC half-bridge switching power supply secondary side driving voltage compensation circuit and method thereof

Abstract

The invention relates to an LLC half-bridge switching power supply secondary side driving voltage compensation circuit and method, and the circuit comprises a secondary side driving voltage input module, a driving voltage detection circuit module, and a grid voltage lifting circuit module which is provided with a switching tube QN1, receives an electric signal outputted by the driving voltage detection circuit module, and outputs the electric signal to the driving voltage detection circuit module. And the driving voltage VF of the secondary side driving voltage input module is adjusted through the on-off state of the driving switch tube. According to the embodiment provided by the invention, whether the driving voltage VF output by the secondary side driving voltage input module is attenuated or not can be monitored, identified and judged through the driving voltage detection circuit module, and when the driving voltage VF is attenuated, the driving voltage VF is correspondingly compensated through the gate voltage lifting circuit module, so that the driving voltage VF can be accurately adjusted. Therefore, the situation that circuit devices are overheated and damaged due to insufficient driving voltage VF is effectively prevented, and the reliability of the whole system is remarkably improved.

Description

Technical Field

[0001] This application relates to the field of switching power supply technology, and in particular to a secondary-side drive voltage compensation circuit and method for an LLC half-bridge switching power supply. Background Technology

[0002] LLC half-bridge switch is a high-efficiency isolated DC-DC conversion topology. By combining the half-bridge switch structure with the LLC resonant cavity, it achieves excellent soft-switching performance and features high efficiency and high power density. Therefore, it is widely used in mid-to-high-end power supply systems.

[0003] In existing technologies, during long-term operation of LLC half-bridge switches, the voltage of the transformer secondary drive circuit gradually decreases over time. Although the transformer primary and drive chip outputs are normal, the on-resistance of the MOSFETs driven by the secondary side increases due to insufficient drive voltage, resulting in a significant increase in temperature rise and posing a risk of overheating damage or even explosion. Summary of the Invention

[0004] This application provides a secondary-side drive voltage compensation circuit and method for an LLC half-bridge switching power supply, aiming to solve the existing technical problem of MOSFETs being damaged due to excessive temperature rise caused by the attenuation of the secondary-side drive voltage during long-term operation of the LLC half-bridge switch.

[0005] In a first aspect, embodiments of this application provide an LLC half-bridge switching power supply secondary-side drive voltage compensation circuit, including: The secondary-side drive voltage input module provides positive and negative voltage drive signals to the system through an external main control chip. The drive voltage detection circuit module is electrically connected to the secondary drive voltage input module. It is used to monitor the drive voltage VF at the secondary drive voltage input module, compare the voltage values, and output the corresponding electrical signal. It also includes a gate voltage boosting circuit module, which is electrically connected to the secondary-side drive voltage input module and the drive voltage detection circuit module. It is equipped with a switching transistor QN1, which receives the electrical signal output by the drive voltage detection circuit module and adjusts the drive voltage VF of the secondary-side drive voltage input module by driving the switching state of the switching transistor.

[0006] Furthermore, the secondary-side drive voltage input module includes: a pulse transformer T1, diodes D2, D3, and D4, resistors R7, R8, and R9, and a transistor Q2. One side of the pulse transformer T1 is connected to an external main control chip, and the other side of the pulse transformer T1 is provided with two sets of interfaces: an upper interface and a lower interface. One end of resistor R7, the anode of diode D2, and the anode of diode D3 are connected in parallel to the upper interface of the pulse transformer T1. The cathode of diode D2 and one end of resistor R8 are electrically connected to the emitter of transistor Q2. The other end of resistor R8 is connected to the drive voltage detection circuit module and the gate voltage boosting circuit module. The cathode of diode D3, the other end of resistor R7, and one end of resistor R9 are connected in parallel to the base of transistor Q2. The collector of transistor Q2 is electrically connected to the anode of diode D4. The cathode of diode D4 and the other end of resistor R9 are connected in parallel to the lower interface of the pulse transformer T1.

[0007] Furthermore, the drive voltage detection circuit module includes: voltage comparator COM1, voltage comparator COM2, resistor R1, and resistor R2. One end of resistor R1 is connected to the drain of the switching transistor QN1. The other end of resistor R1 and one end of resistor R2 are connected in parallel to the non-inverting input of voltage comparator COM1. The inverting input of voltage comparator COM1 and the non-inverting input of voltage comparator COM2 are connected in parallel to the VF port and connected to the secondary drive voltage input module. The inverting input of voltage comparator COM2 and the other end of resistor R2 are respectively connected to special ground GND-T. The outputs of voltage comparator COM1 and voltage comparator COM2 are respectively connected to the gate voltage boosting circuit module.

[0008] Furthermore, a control logic circuit module is provided at the rear end of the drive voltage detection circuit module. The output terminals of voltage comparator COM1 and voltage comparator COM2 are respectively connected to the control logic circuit module, and the output terminal of the control logic circuit module is connected to the gate voltage boosting circuit module.

[0009] Furthermore, the control logic circuit module includes an AND gate logic operation module U1, the output terminals of voltage comparator COM1 and voltage comparator COM2 are respectively connected to the two sets of input terminals of the AND gate logic operation module U1, and the output terminal of the AND gate logic operation module U1 is connected to the gate voltage boosting circuit module.

[0010] Furthermore, the gate voltage boosting circuit module also includes: an operational amplifier AMP, a diode D1, resistors R3, R4, R5, and R6. The non-inverting input of the operational amplifier AMP is electrically connected to one end of resistor R3, and the other end of resistor R3 is electrically connected to the output of the AND gate logic operation module U1 of the control logic circuit module. The inverting input of the operational amplifier AMP is electrically connected to one end of resistor R4 and one end of resistor R5. The other end of resistor R4 is connected to a special ground GND-T. The output of the operational amplifier AMP is electrically connected to the other end of resistor R5 and the gate of the switching transistor QN1. The source of the switching transistor QN1 is connected to one end of resistor R6, and the other end of resistor R6 is connected to the secondary-side drive voltage input module.

[0011] Secondly, embodiments of this application also provide a method for compensating the secondary drive voltage of an LLC half-bridge switching power supply, based on the LLC half-bridge switching power supply secondary drive voltage compensation circuit described above, including the following steps: The power supply from the external main control chip is transmitted to the secondary drive voltage input module via pulse transformer T1. The drive voltage detection circuit module monitors and judges the drive voltage VF of the secondary drive voltage input module to determine whether the drive amplitude of the drive voltage VF has attenuated. If the driving amplitude decreases, the gate voltage boosting circuit module will activate, turning on the switching transistor QN1 and boosting the gate voltage of the main power transistor QH. This ensures gate voltage compensation of the secondary driving voltage input module, keeping the driving voltage VF of the driving voltage input module stable. In this way, the secondary driving voltage input module is transformed into a compensated voltage output module.

[0012] Furthermore, the specific steps for the drive voltage detection circuit module to monitor the drive voltage VF of the secondary drive voltage input module are as follows: If the driving voltage VF is lower than the set voltage value, the lower driving voltage signal passes through the driving voltage detection circuit module, and is compared with the voltage divider signal through resistors R1 and R2 by voltage comparator COM1. At the same time, the driving voltage signal is compared with the 0V signal by voltage comparator COM2, and the comparison result is output.

[0013] Furthermore, the comparison results output by voltage comparator COM1 and voltage comparator COM2 are processed by the AND gate logic operation module U1 of the control logic circuit module and output with corresponding levels.

[0014] Furthermore, when the level output by the control logic circuit module is different from the level output during normal operation, the gate voltage boosting circuit module is activated to boost the voltage at the gate of the main power transistor QH, thereby compensating for the drive voltage VF of the secondary drive voltage input module.

[0015] This application provides a secondary-side drive voltage compensation circuit and method for an LLC half-bridge switching power supply. The embodiment provided in this application monitors and identifies whether the drive voltage VF output from the secondary-side drive voltage input module is attenuating through a drive voltage detection circuit module. When drive voltage VF attenuation occurs, a gate voltage boosting circuit module compensates for the drive voltage VF accordingly. This effectively prevents overheating and damage to circuit components due to insufficient drive voltage VF, significantly improving the overall system reliability.

[0016] In the embodiments provided in this application, the compensation method automatically adjusts the compensation based on the actual voltage attenuation level, requiring no manual intervention, resulting in fast response efficiency and avoiding the delay problems associated with manual operation. This ensures continuous operation of the overall circuit without affecting normal working conditions. By automatically adjusting the driving voltage VF, the overall circuit can be maintained at the optimal driving voltage state, reducing stress on the components in the circuit and thus extending the power supply's lifespan. Furthermore, since the embodiments provided in this application are implemented using only simple hardware circuits, the overall cost is relatively low, and it is easy to improve and upgrade existing technologies. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 This is a connection diagram of an LLC half-bridge converter.

[0021] Figure 2 This is a general block diagram of the voltage compensation circuit technical solution.

[0022] Figure 3 This is a circuit diagram of a secondary drive voltage compensation circuit for an LLC half-bridge switching power supply provided in an embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0025] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0026] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0027] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0028] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0029] To address the existing technical problem of MOSFET overheating and damage caused by secondary-side drive voltage decay during long-term operation of LLC half-bridge switches, this application provides a secondary-side drive voltage compensation circuit and method for LLC half-bridge switching power supplies. This circuit monitors and identifies whether the drive voltage VF output from the secondary-side drive voltage input module is decaying through a drive voltage detection circuit module. When VF decays, a gate voltage boosting circuit module compensates for the decay, effectively preventing overheating and damage to circuit components due to insufficient drive voltage VF, and significantly improving the overall system reliability.

[0030] Please see Figure 1 , Figure 2 as well as Figure 3 In a first aspect, embodiments of this application provide an LLC half-bridge switching power supply secondary-side drive voltage compensation circuit, comprising: The secondary-side drive voltage input module provides positive and negative voltage drive signals to the system through an external main control chip. The drive voltage detection circuit module is electrically connected to the secondary drive voltage input module. It is used to monitor the drive voltage VF at the secondary drive voltage input module, compare the voltage values, and output the corresponding electrical signal. It also includes a gate voltage boosting circuit module, which is electrically connected to the secondary-side drive voltage input module and the drive voltage detection circuit module. It is equipped with a switching transistor QN1, which receives the electrical signal output by the drive voltage detection circuit module and adjusts the drive voltage VF of the secondary-side drive voltage input module by driving the switching state of the switching transistor.

[0031] In this embodiment, the nominal driving voltage of the transformer secondary side is 12V. In the prior art, under long-term operating conditions, the driving voltage VF gradually decreases to 8-9V due to aging, and in severe cases, even drops to 7V. Although the output of the transformer primary side and the main control chip is normal, the on-resistance of the secondary side switching transistor QN1 increases due to insufficient driving voltage, resulting in a significant increase in temperature rise, posing a risk of overheating damage or even explosion. In the embodiment provided in this application, the main control chip generates a positive and negative driving voltage VF signal with an adjustable frequency and a duty cycle of 50% at the secondary driving voltage input module to provide the LLC resonant system. The driving voltage detection circuit module monitors the driving voltage VF of the secondary driving voltage input module in real time and compares it with the set value of the reference voltage, i.e., 12V, and outputs a corresponding level to the gate voltage boosting circuit based on the detection result. In this application, when the driving voltage VF is less than the reference voltage, a high level is output to the gate voltage boosting circuit module. When the gate voltage boosting circuit module receives a high level, it boosts the gate voltage of the switching transistor QH. This provides gate voltage compensation to the drive voltage VF of the secondary-side drive voltage input module, preventing the main power transistor QH connected to the secondary-side drive voltage input module from becoming unsaturated due to an excessively low drive voltage VF, which could lead to overheating and ultimately transistor failure. Simultaneously, by compensating for the drive voltage VF, it stabilizes, effectively controlling the temperature rise of the main power transistor QH. After passing through the secondary-side drive voltage input module, it reaches thermal equilibrium again in the harsh environment, ensuring a stable and reliable overall operation.

[0032] In some optional embodiments, the secondary-side drive voltage input module includes: a pulse transformer T1, diodes D2, D3, and D4, resistors R7, R8, and R9, and a transistor Q2. One side of the pulse transformer T1 is connected to an external main control chip, and the other side of the pulse transformer T1 is provided with two sets of interfaces: an upper interface and a lower interface. One end of resistor R7, the anode of diode D2, and the anode of diode D3 are connected in parallel to the upper interface of the pulse transformer T1. The cathode of diode D2 and one end of resistor R8 are electrically connected to the emitter of transistor Q2. The other end of resistor R8 is connected to the drive voltage detection circuit module and the gate voltage boosting circuit module. The cathode of diode D3, the other end of resistor R7, and one end of resistor R9 are connected in parallel to the base of transistor Q2. The collector of transistor Q2 is electrically connected to the anode of diode D4. The cathode of diode D4 and the other end of resistor R9 are connected in parallel to the lower interface of the pulse transformer T1.

[0033] During operation, the peripheral main control chip is powered through OUTA, and the voltage is transmitted to the secondary drive voltage input module via pulse transformer T1. At this time, the voltage is positive at the top and negative at the bottom, driving the upper bridge. Through diode D2 and resistor R8, a high-level output is generated, turning on the main power transistor QH, while transistor Q2 is off. When the main control chip's OUTA is de-energized, the voltage is transmitted to the secondary drive voltage input module via pulse transformer T1. The voltage is then negative at the top and positive at the bottom, driving the upper bridge. Through resistors R7 and R9, diode D4, and resistor R8, resistor R8 discharges, resulting in a low-level output that turns off the main power transistor QH. Transistor Q2 is then on, accelerating the gate discharge turn-off process. At this point, due to the voltage drop across transistor Q2 and the reverse voltage drop across diode D4, a continuous -4V turn-off voltage exists at the gate. This cycle repeats, driving the main power transistor QH normally. If the drive amplitude does not attenuate during prolonged use, the drive voltage compensation circuit does not operate, and this circuit powers the LLC output normally.

[0034] In some optional embodiments, the drive voltage detection circuit module includes: voltage comparator COM1, voltage comparator COM2, resistor R1, and resistor R2. One end of resistor R1 is connected to the drain of switching transistor QN1. The other end of resistor R1 and one end of resistor R2 are connected in parallel to the non-inverting input of voltage comparator COM1. The inverting input of voltage comparator COM1 and the non-inverting input of voltage comparator COM2 are connected in parallel to the VF port and connected to the secondary drive voltage input module. The inverting input of voltage comparator COM2 and the other end of resistor R2 are respectively connected to special ground GND-T. The outputs of voltage comparator COM1 and voltage comparator COM2 are respectively connected to the gate voltage boosting circuit module. Resistors R1 and R2 are precision resistors. If the positive voltage amplitude of the drive voltage decreases and falls below 12V, the drive voltage detection circuit module will operate. The drive voltage VF will be compared with the voltage divider signal through precision resistors R1 and R2 via voltage comparator COM1. At the same time, the drive voltage VF will be compared with the 0V signal via voltage comparator COM2, and the comparison result will be output.

[0035] In some optional embodiments, a control logic circuit module is provided at the rear end of the drive voltage detection circuit module. The outputs of voltage comparators COM1 and COM2 are respectively connected to the control logic circuit module, and the output of the control logic circuit module is connected to the gate voltage boosting circuit module. When a first set threshold of the drive voltage VF is detected, the control logic circuit module generates a corresponding signal to activate the gate voltage boosting circuit module. The control logic circuit module includes an AND gate logic operation module U1. The outputs of voltage comparators COM1 and COM2 are respectively connected to the two sets of inputs of the AND gate logic operation module U1, and the output of the AND gate logic operation module U1 is connected to the gate voltage boosting circuit module. After the drive voltage VF is compared by voltage comparators COM1 and COM2, voltage comparators COM1 and COM2 respectively output corresponding levels. In the embodiments provided in this application, when the driving voltage VF is positive, if VF is greater than 12V, voltage comparator COM1 outputs a low level and voltage comparator COM2 outputs a high level, and the AND gate logic module U1 outputs a low level. If the driving voltage VF is less than 12V, voltage comparator COM1 outputs a high level and voltage comparator COM2 outputs a high level, and the AND gate logic module U1 outputs a high level. When the driving voltage VF is negative, voltage comparator COM1 outputs a high level and voltage comparator COM2 outputs a low level, and the AND gate logic module U1 outputs a low level. Based on the level output by the AND gate logic module U1, when the driving voltage VF decays, a corresponding high level is sent to the gate voltage boosting circuit module to drive the gate voltage boosting circuit module to perform corresponding gate voltage compensation.

[0036] In some optional embodiments, the gate voltage boosting circuit module further includes: an operational amplifier AMP, a diode D1, resistors R3, R4, R5, and R6. The non-inverting input of the operational amplifier AMP is electrically connected to one end of resistor R3, and the other end of resistor R3 is electrically connected to the output of the AND gate logic operation module U1 of the control logic circuit module. The inverting input of the operational amplifier AMP is electrically connected to one end of resistor R4 and one end of resistor R5. The other end of resistor R4 is connected to a special ground GND-T. The output of the operational amplifier AMP is electrically connected to the other end of resistor R5 and the gate of the switching transistor QN1. The source of the switching transistor QN1 is connected to one end of resistor R6, and the other end of resistor R6 is connected to the secondary-side drive voltage input module. When the AND gate logic operation module U1 of the control logic circuit module outputs a high level, it is connected to the non-inverting input of the operational amplifier AMP through resistor R3. The operational amplifier AMP outputs a high level, ensuring that the switching transistor QN1 is turned on. This pulls up VCC-T, which flows into the gate of the main power transistor QH through resistor R6 and diode D1, raising the gate voltage. This ensures that the circuit of the secondary drive voltage input module receives gate voltage compensation, preventing the main power transistor QH from being unsaturated due to insufficient drive voltage, which could lead to overheating or even transistor failure. At the same time, because the drive voltage VF is compensated by the gate voltage, the temperature rise of the main power transistor QH is effectively controlled, allowing the overall circuit to reach thermal equilibrium and ensuring the stability and safety of the circuit.

[0037] Secondly, embodiments of this application also provide a method for compensating the secondary drive voltage of an LLC half-bridge switching power supply, based on the LLC half-bridge switching power supply secondary drive voltage compensation circuit described above, including the following steps: The power supply from the external main control chip is transmitted to the secondary drive voltage input module via pulse transformer T1. The drive voltage detection circuit module monitors and judges the drive voltage VF of the secondary drive voltage input module to determine whether the drive amplitude of the drive voltage VF has attenuated. If the driving amplitude decreases, the gate voltage boosting circuit module will activate, turning on the switching transistor QN1 and boosting the gate voltage of the main power transistor QH. This ensures gate voltage compensation of the secondary driving voltage input module, keeping the driving voltage VF of the driving voltage input module stable. In this way, the secondary driving voltage input module is transformed into a compensated voltage output module.

[0038] In some optional embodiments, the specific steps by which the drive voltage detection circuit module monitors the drive voltage VF of the secondary drive voltage input module are as follows: If the driving voltage VF is lower than the set voltage value, the lower driving voltage signal passes through the driving voltage detection circuit module, and is compared with the voltage divider signal through resistors R1 and R2 by voltage comparator COM1. At the same time, the driving voltage signal is compared with the 0V signal by voltage comparator COM2, and the comparison result is output.

[0039] In some optional embodiments, the comparison results output by voltage comparator COM1 and voltage comparator COM2 are passed through the AND gate logic operation module U1 of the control logic circuit module and output the corresponding level.

[0040] In some optional embodiments, when the level output by the control logic circuit module is different from the level output during normal operation, the gate voltage boosting circuit module is activated to boost the voltage at the gate of the main power transistor QH, thereby compensating for the drive voltage VF of the secondary drive voltage input module.

[0041] In the embodiments provided in this application, taking the secondary-side bridge as an example, the method for compensating the secondary-side drive voltage of an LLC half-bridge switching power supply is divided into four stages, wherein: Phase 1: The peripheral main control chip is powered through OUTA, and the voltage is transmitted to the secondary drive voltage input module via pulse transformer T1. At this time, the voltage is positive at the top and negative at the bottom, driving the upper bridge. Through diode D2 and resistor R8, a high-level output is generated, turning on the main power transistor QH, while transistor Q2 is off. When the main control chip's OUTA is de-energized, the voltage is transmitted to the secondary drive voltage input module via pulse transformer T1. The voltage is now negative at the top and positive at the bottom, driving the upper bridge. Through resistors R7 and R9, diode D4, and resistor R8, resistor R8 discharges, generating a low-level output that turns off the main power transistor QH. Transistor Q2 is now on, accelerating the gate discharge turn-off process. At this time, due to the voltage drop across transistor Q2 and the reverse voltage drop across diode D4, a continuous -4V turn-off voltage exists at the gate. This cycle repeats, driving the main power transistor QH normally. If the drive amplitude does not attenuate during prolonged use, the drive voltage compensation circuit does not operate, and this circuit powers the LLC output normally.

[0042] Second stage: If the positive voltage amplitude of the drive decreases and falls below 12V, the drive voltage detection circuit module will work. The drive voltage VF will be compared with the voltage divider signal through precision resistors R1 and R2 by voltage comparator COM1. At the same time, the drive voltage VF will be compared with the 0V signal by voltage comparator COM2, and the comparison result will be output.

[0043] Third stage: Voltage comparators COM1 and COM2 output voltage through AND gate logic module U1. The output control logic is as follows: (1) When the driving voltage VF is positive: If the driving voltage VF > 12V, then the voltage comparator COM1 outputs a low level, the voltage comparator COM2 outputs a high level, and the AND gate logic operation module U1 outputs a low level. If the driving voltage VF is less than 12V, the output of voltage comparator COM1 is high, the output of voltage comparator COM2 is high, and the output of AND gate logic operation module U1 is high.

[0044] (2) When the driving voltage VF is negative: If the driving voltage VF < 0V, then the voltage comparator COM1 outputs a high level, the voltage comparator COM2 outputs a low level, and the AND gate logic operation module U1 outputs a low level.

[0045] Phase Four: When the AND gate logic operation module U1 of the control logic circuit module outputs a high level, it is connected to the non-inverting input of the operational amplifier AMP through resistor R3. The operational amplifier AMP outputs a high level, ensuring that the switching transistor QN1 is turned on. This pulls up VCC-T, which flows through resistor R6 and diode D1 into the gate of the main power transistor QH, raising the gate voltage. This ensures that the secondary-side drive voltage input module receives gate voltage compensation, preventing the main power transistor QH from becoming unsaturated due to insufficient drive voltage, which could lead to overheating or even transistor failure. Simultaneously, because the drive voltage VF is compensated by the gate voltage, the secondary-side drive voltage input module is transformed into a compensated voltage output module, effectively controlling the temperature rise of the main power transistor QH and allowing the overall circuit to reach thermal equilibrium, ensuring circuit stability and safety. After this phase is completed, the operation transitions back to Phase One.

[0046] The LLC half-bridge switching power supply secondary-side drive voltage compensation method provided in the above embodiments is a detailed description of the upper-side circuit of the LLC half-bridge switching circuit. The secondary-side circuit of an LLC half-bridge switching power supply is generally divided into an upper-side circuit and a lower-side circuit. Through the coordinated operation of the upper and lower-side circuits, the DC input is converted into a high-frequency square wave voltage. In the embodiments provided in this application, the modules of the upper and lower-side circuits are identical. Therefore, if the secondary-side drive voltage input module in the lower-side circuit experiences attenuation, it can also be supplemented accordingly through the embodiments provided in this application, thereby transforming the secondary-side drive voltage input module into a compensated voltage output module. This ensures both thermal balance and circuit stability and safety.

[0047] This application provides a secondary-side drive voltage compensation circuit and method for an LLC half-bridge switching power supply. The embodiment provided in this application monitors and identifies whether the drive voltage VF output from the secondary-side drive voltage input module is attenuating through a drive voltage detection circuit module. When drive voltage VF attenuation occurs, a gate voltage boosting circuit module compensates for the drive voltage VF accordingly. This effectively prevents overheating and damage to circuit components due to insufficient drive voltage VF, significantly improving the overall system reliability.

[0048] In the embodiments provided in this application, the compensation method automatically adjusts the compensation based on the actual voltage attenuation level, requiring no manual intervention, resulting in fast response efficiency and avoiding the delay problems associated with manual operation. This ensures continuous operation of the overall circuit without affecting normal working conditions. By automatically adjusting the driving voltage VF, the overall circuit can be maintained at the optimal driving voltage state, reducing stress on the components in the circuit and thus extending the power supply's lifespan. Furthermore, since the embodiments provided in this application are implemented using only simple hardware circuits, the overall cost is relatively low, and it is easy to improve and upgrade existing technologies.

[0049] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0050] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For example, the division of each unit is merely a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0051] The steps in the methods of this application embodiment can be adjusted, merged, or deleted according to actual needs. The units in the apparatus of this application embodiment can be merged, divided, or deleted according to actual needs. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0052] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a terminal, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0053] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0054] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Since these modifications and variations fall within the scope of the claims and their equivalents, this application also intends to include these modifications and variations.

[0055] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A secondary-side drive voltage compensation circuit for an LLC half-bridge switching power supply, characterized in that, include: The secondary-side drive voltage input module provides positive and negative voltage drive signals to the system through an external main control chip. The drive voltage detection circuit module is electrically connected to the secondary drive voltage input module. It is used to monitor the drive voltage VF at the secondary drive voltage input module, compare the voltage values, and output the corresponding electrical signal. It also includes a gate voltage boosting circuit module, which is electrically connected to the secondary-side drive voltage input module and the drive voltage detection circuit module. It is equipped with a switching transistor QN1, which receives the electrical signal output by the drive voltage detection circuit module and adjusts the drive voltage VF of the secondary-side drive voltage input module by driving the switching state of the switching transistor.

2. The LLC half-bridge switching power supply secondary-side drive voltage compensation circuit according to claim 1, characterized in that, The secondary-side drive voltage input module includes: a pulse transformer T1, diodes D2, D3, and D4, resistors R7, R8, and R9, and a transistor Q2. One side of the pulse transformer T1 is connected to an external main control chip, and the other side of the pulse transformer T1 has two sets of interfaces: an upper interface and a lower interface. One end of resistor R7, the anode of diode D2, and the anode of diode D3 are connected in parallel to the upper interface of the pulse transformer T1. The cathode of diode D2 and one end of resistor R8 are electrically connected to the emitter of transistor Q2. The other end of resistor R8 is connected to the drive voltage detection circuit module and the gate voltage boosting circuit module. The cathode of diode D3, the other end of resistor R7, and one end of resistor R9 are connected in parallel to the base of transistor Q2. The collector of transistor Q2 is electrically connected to the anode of diode D4. The cathode of diode D4 and the other end of resistor R9 are connected in parallel to the lower interface of the pulse transformer T1.

3. The LLC half-bridge switching power supply secondary-side drive voltage compensation circuit according to claim 1, characterized in that, The drive voltage detection circuit module includes: voltage comparator COM1, voltage comparator COM2, resistor R1, and resistor R2. One end of resistor R1 is connected to the drain of switching transistor QN1. The other end of resistor R1 and one end of resistor R2 are connected in parallel to the non-inverting input of voltage comparator COM1. The inverting input of voltage comparator COM1 and the non-inverting input of voltage comparator COM2 are connected in parallel to the VF port and connected to the secondary drive voltage input module. The inverting input of voltage comparator COM2 and the other end of resistor R2 are respectively connected to special ground GND-T. The outputs of voltage comparator COM1 and voltage comparator COM2 are respectively connected to the gate voltage boosting circuit module.

4. The LLC half-bridge switching power supply secondary-side drive voltage compensation circuit according to claim 3, characterized in that, The drive voltage detection circuit module is backed by a control logic circuit module. The outputs of voltage comparator COM1 and voltage comparator COM2 are respectively connected to the control logic circuit module. The output of the control logic circuit module is connected to the gate voltage boosting circuit module.

5. The LLC half-bridge switching power supply secondary-side drive voltage compensation circuit according to claim 4, characterized in that, The control logic circuit module includes an AND gate logic operation module U1. The output terminals of voltage comparator COM1 and voltage comparator COM2 are respectively connected to the two sets of input terminals of the AND gate logic operation module U1. The output terminal of the AND gate logic operation module U1 is connected to the gate voltage boosting circuit module.

6. The LLC half-bridge switching power supply secondary-side drive voltage compensation circuit according to claim 5, characterized in that, The gate voltage boosting circuit module further includes: an operational amplifier AMP, a diode D1, resistors R3, R4, R5, and R6. The non-inverting input of the operational amplifier AMP is electrically connected to one end of resistor R3, and the other end of resistor R3 is electrically connected to the output of the AND gate logic operation module U1 of the control logic circuit module. The inverting input of the operational amplifier AMP is electrically connected to one end of resistor R4 and one end of resistor R5. The other end of resistor R4 is connected to a special ground GND-T. The output of the operational amplifier AMP is electrically connected to the other end of resistor R5 and the gate of the switching transistor QN1. The source of the switching transistor QN1 is connected to one end of resistor R6, and the other end of resistor R6 is connected to the secondary-side drive voltage input module.

7. A method for compensating the secondary drive voltage of an LLC half-bridge switching power supply, based on the LLC half-bridge switching power supply secondary drive voltage compensation circuit as described in any one of claims 1 to 6, characterized in that, Includes the following steps: The power supply from the external main control chip is transmitted to the secondary drive voltage input module via pulse transformer T1. The drive voltage detection circuit module monitors and judges the drive voltage VF of the secondary drive voltage input module to determine whether the drive amplitude of the drive voltage VF has attenuated. If the driving amplitude decreases, the gate voltage boosting circuit module will activate, turning on the switching transistor QN1 and boosting the gate voltage of the main power transistor QH. This ensures gate voltage compensation of the secondary driving voltage input module, keeping the driving voltage VF of the driving voltage input module stable. In this way, the secondary driving voltage input module is transformed into a compensated voltage output module.

8. The LLC half-bridge switching power supply secondary-side drive voltage compensation method according to claim 7, characterized in that, The specific steps by which the drive voltage detection circuit module monitors the drive voltage VF of the secondary drive voltage input module are as follows: If the driving voltage VF is lower than the set voltage value, the lower driving voltage signal passes through the driving voltage detection circuit module, and is compared with the voltage divider signal through resistors R1 and R2 by voltage comparator COM1. At the same time, the driving voltage signal is compared with the 0V signal by voltage comparator COM2, and the comparison result is output.

9. The LLC half-bridge switching power supply secondary-side drive voltage compensation method according to claim 8, characterized in that, The comparison results output by voltage comparator COM1 and voltage comparator COM2 are processed by the AND gate logic operation module U1 of the control logic circuit module and the corresponding level is output.

10. The LLC half-bridge switching power supply secondary-side drive voltage compensation method according to claim 9, characterized in that, When the level output by the control logic circuit module is different from the level output during normal operation, the gate voltage boosting circuit module is activated to boost the voltage at the gate of the main power transistor QH, thereby compensating for the drive voltage VF of the secondary drive voltage input module.

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