Switching power supply control system and control method thereof

Abstract

The application provides a switching power supply control system and a control method thereof. The switching power supply control system comprises a main power circuit, a compensation circuit and a feedback circuit. A first end of the main power circuit is connected with a first end of the feedback circuit, and a second end of the main power circuit is connected with a second end of the feedback circuit. A third end of the main power circuit is connected with a first end of the compensation circuit. A second end of the compensation circuit is connected with a third end of the feedback circuit. A third end of the compensation circuit is connected with a fourth end of the feedback circuit. A variable impedance element is arranged in the compensation circuit, and the variable impedance element is used for changing its resistance value according to the load of the main power circuit. By arranging the variable impedance element in the compensation circuit and making the variable impedance element change its resistance value according to the load change of the main power circuit, the transfer function of the compensation circuit can be adjusted, so that the application requirement of the switching power supply can be met while the dynamic response performance of the system is ensured.

Description

Technical Field

[0001] This application relates to the field of switching power supply technology, and in particular to a switching power supply control system and control method thereof. Background Technology

[0002] As the core power supply unit for various electronic devices, the stability of the control loop of a switching power supply directly determines the reliability of the entire device. Existing conventional switching power supplies rely on a compensation network composed of fixed resistors and capacitors to construct the control loop. These compensation parameters are fixed after factory testing and cannot be adjusted in real time according to actual operating conditions.

[0003] However, during actual operation, the load conditions of electronic devices will dynamically switch between heavy load and light load ranges. The change in load resistance will change the overall transfer function of the system, causing the control loop crossover frequency to shift, which in turn degrades the phase margin and system bandwidth, and is very likely to cause stability failures such as power output oscillation and slow transient response.

[0004] To address the aforementioned issue of insufficient load adaptability, existing solutions often rely on complex digital control algorithms to achieve dynamic parameter adjustment. While this has some effect, it comes at the cost of high hardware and is difficult to implement in software. In the field of analog control, there is currently a lack of low-cost, simple adaptive adjustment schemes, which makes it difficult to meet the needs of mass applications of small and medium power analog switching power supplies. Summary of the Invention

[0005] This application provides a switching power supply control system and control method to solve the technical problem of control loop cross-frequency shift and system stability degradation caused by load changes in existing solutions.

[0006] In a first aspect of the embodiments of this application, a switching power supply control system is provided, the switching power supply control system comprising: a main power circuit, a compensation circuit, and a feedback circuit; The first terminal of the main power circuit is connected to the first terminal of the feedback circuit, and the second terminal of the main power circuit is connected to the second terminal of the feedback circuit. The third terminal of the main power circuit is connected to the first terminal of the compensation circuit; The second terminal of the compensation circuit is connected to the third terminal of the feedback circuit; the third terminal of the compensation circuit is connected to the fourth terminal of the feedback circuit. The compensation circuit is equipped with a variable impedance element, which is used to change its resistance value according to the load of the main power circuit.

[0007] In one optional implementation, the compensation circuit includes a control module, a digital-to-analog converter module, a current-limiting resistor, and a first diode; The first terminal of the control module is connected to the third terminal of the main power circuit, and the second terminal of the control module is connected to the first terminal of the digital-to-analog converter module. The second terminal of the digital-to-analog converter module is connected to the first terminal of the first diode, the second terminal of the first diode is connected to the first terminal of the current-limiting resistor, and the second terminal of the current-limiting resistor is grounded.

[0008] In one optional implementation, the compensation circuit includes a first capacitor; The first terminal of the first capacitor is connected to the third terminal of the feedback circuit, and the second terminal of the first capacitor is connected to the first terminal of the variable impedance element. The second terminal of the variable impedance element is connected to the fourth terminal of the feedback circuit.

[0009] In an alternative implementation, the first diode and the variable impedance element are housed in a hermetically sealed package.

[0010] In an optional implementation, the variable impedance element is a photoresistor.

[0011] In one optional implementation, the feedback circuit includes a first sampling resistor, a second sampling resistor, a gate driver, a pulse modulator, a compensation resistor, an error amplifier, and a second capacitor. The first end of the first sampling resistor is connected to the first end of the main power circuit; The second end of the first sampling resistor is connected to the first end of the compensation resistor and the first end of the second sampling resistor, respectively, and the second end of the second sampling resistor is grounded; The second end of the compensation resistor is connected to the first end of the first capacitor, the first end of the second capacitor, and the first end of the error amplifier, respectively. The first terminal of the pulse modulator is connected to the second terminal of the error amplifier, the second terminal of the variable impedance element, and the second terminal of the second capacitor, respectively. The second terminal of the pulse modulator is connected to the first terminal of the gate driver, and the second terminal of the gate driver is connected to the second terminal of the main power circuit.

[0012] In one optional implementation, the main power circuit includes a second diode, a power switch, a flyback transformer, an energy storage capacitor, and a parasitic resistor; The first terminal of the flyback transformer is connected to the first terminal of the second diode, and the second terminal of the second diode is connected to the first terminal of the energy storage capacitor and the first terminal of the first sampling resistor, respectively. The second terminal of the flyback transformer is connected to the second terminal of the parasitic resistor and the second terminal of the second sampling resistor, respectively, and then grounded together. The second terminal of the energy storage capacitor is connected to the first terminal of the parasitic resistor; The first terminal of the power switch is connected to the third terminal of the flyback transformer, the second terminal of the power switch is connected to the second terminal of the gate driver, and the third terminal of the power switch is grounded. The fourth terminal of the flyback transformer is connected to the DC bus.

[0013] In one optional implementation, the main power circuit includes a load module and a third sampling resistor; The first end of the load module is connected to the first end of the first sampling resistor and the first end of the energy storage capacitor, respectively. The second end of the load module is connected to the first end of the control module and the first end of the third sampling resistor, respectively. The second terminal of the third sampling resistor is connected to the second terminal of the flyback transformer, the second terminal of the parasitic resistor, and the second terminal of the second sampling resistor, respectively.

[0014] In a second aspect of this embodiment, a control method for a switching power supply control system is also provided, applied to the switching power supply control system described in any one of the first aspects above, the method comprising: Obtain the feedback signal from the main power circuit; The drive current is determined based on the feedback signal, so as to change the resistance value of the variable impedance element.

[0015] In an optional implementation, obtaining the feedback signal from the main power circuit includes: Collect the voltage value of the third sampling resistor in the main power circuit; The feedback signal of the main power circuit is determined based on the voltage value and the resistance value of the third sampling resistor.

[0016] The switching power supply control system provided in this application includes: a main power circuit, a compensation circuit, and a feedback circuit; a first terminal of the main power circuit is connected to a first terminal of the feedback circuit, and a second terminal of the main power circuit is connected to a second terminal of the feedback circuit; a third terminal of the main power circuit is connected to a first terminal of the compensation circuit; a second terminal of the compensation circuit is connected to a third terminal of the feedback circuit; and a fourth terminal of the compensation circuit is connected to a fourth terminal of the feedback circuit. A variable impedance element is provided in the compensation circuit, which changes its resistance value according to the load of the main power circuit. This technical solution, by setting a variable impedance element in the compensation circuit and allowing the variable impedance element to change its resistance value according to the load change of the main power circuit, can adjust the transfer function of the compensation circuit to offset the system transfer function drift caused by load changes. Since this adjustment process only relies on the physical characteristics of the variable impedance element and does not require complex digital control algorithms, it can achieve adaptive adjustment of the control loop with lower hardware costs and implementation difficulty. Furthermore, the resistance value of the variable impedance element can be continuously adjusted according to the load change, so that the transfer function of the compensation circuit can be dynamically matched with different load conditions. This can ensure the dynamic response performance of the system while meeting the application requirements of the switching power supply. 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 schematic diagram of the structure of a switching power supply control system provided in an embodiment of this application; Figure 2 This is a schematic diagram of another switching power supply control system provided in an embodiment of this application; Figure 3 A schematic diagram illustrating the implementation flow of a control method for a switching power supply control system provided in this application embodiment; Figure 4A schematic diagram illustrating the implementation process of a method for acquiring a feedback signal provided in an embodiment of this application; Figure 5 This is a schematic diagram illustrating the implementation process of another control method for a switching power supply control system provided in an embodiment of this application. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] To address the technical problem in existing technologies where load variations lead to control loop cross-frequency shifts and decreased system stability, the switching power supply control system provided in this application includes: a main power circuit, a compensation circuit, and a feedback circuit; a first terminal of the main power circuit is connected to a first terminal of the feedback circuit, and a second terminal of the main power circuit is connected to a second terminal of the feedback circuit; a third terminal of the main power circuit is connected to a first terminal of the compensation circuit; a second terminal of the compensation circuit is connected to a third terminal of the feedback circuit; a third terminal of the compensation circuit is connected to a fourth terminal of the feedback circuit; the compensation circuit includes a variable impedance element, which changes its resistance value according to the load of the main power circuit.

[0024] Its core concept is to set a variable impedance element in the compensation circuit and make the resistance value of the variable impedance element change accordingly with the load of the main power circuit, thereby dynamically adjusting the transfer function of the compensation network to counteract the drift of the system transfer function caused by load changes.

[0025] This technical solution incorporates a variable impedance element in the compensation circuit, allowing this element to adjust its resistance based on load changes in the main power circuit. This adjusts the transfer function of the compensation circuit to counteract the system transfer function drift caused by load variations. Since this adjustment process relies solely on the physical characteristics of the variable impedance element, without the need for complex digital control algorithms, it enables adaptive adjustment of the control loop with lower hardware costs and implementation complexity. Furthermore, the resistance of the variable impedance element can be continuously adjusted with load changes, allowing the transfer function of the compensation circuit to dynamically match different load conditions. This ensures both system dynamic response performance and meets the application requirements of switching power supplies.

[0026] like Figure 1 The diagram shown is a structural schematic of a switching power supply control system provided in an embodiment of this application. The switching power supply control system 10 includes: a main power circuit 11, a compensation circuit 12, and a feedback circuit 13.

[0027] The first terminal of the main power circuit 11 is connected to the first terminal of the feedback circuit 13, and the second terminal of the main power circuit 11 is connected to the second terminal of the feedback circuit 13.

[0028] The third terminal of the main power circuit 11 is connected to the first terminal of the compensation circuit 12.

[0029] The second terminal of the compensation circuit 12 is connected to the third terminal of the feedback circuit 13; the third terminal of the compensation circuit 12 is connected to the fourth terminal of the feedback circuit 13.

[0030] The compensation circuit 12 is equipped with a variable impedance element 12-1, which is used to change its resistance value according to the load of the main power circuit 11.

[0031] The aforementioned main power circuit 11 is the core power stage component responsible for power conversion in the switching power supply control system 10. Its function is to convert the DC power input from the DC bus into a stable DC output voltage required by the load. The main power circuit 11 is a power conversion circuit, operating at high voltage and high current power levels, and is the primary power processing stage in the entire switching power supply system. The main power circuit 11 can employ isolated topologies such as flyback, forward, push-pull, half-bridge, or full-bridge, or non-isolated topologies such as buck, boost, or buck-boost.

[0032] The aforementioned compensation circuit 12 is the core control component of the switching power supply control system 10, responsible for signal processing and loop compensation. Its function is to amplify and compensate the phase of the feedback signal output from the feedback circuit 13, generating an error amplification signal that is output to the feedback circuit 13 to adjust the duty cycle of the power switch, thereby stabilizing the output voltage. The compensation circuit 12 can employ a type II error amplifier structure. The compensation circuit 12 includes a variable impedance element 12-1, which is a key adjustment element in the compensation circuit 12. Its resistance changes in response to variations in the load of the main power circuit 11, thereby adjusting the zero-pole frequency of the compensation circuit 12.

[0033] The aforementioned feedback circuit 13 is a mixed signal processing section in the switching power supply control system 10 responsible for signal sampling, pulse modulation, and power driving. It is used to acquire the voltage signal of the main power circuit 11 and process it into a feedback signal suitable for the input of the compensation circuit 12; it is also used to receive the error amplification signal output from the compensation circuit 12 and convert it into a pulse width modulation signal with a corresponding duty cycle; furthermore, it can be used to amplify the pulse width modulation signal to drive the power switching transistors in the main power circuit 11.

[0034] In the embodiments of this application, such as Figure 1 As shown, the switching power supply control system 10 includes: a main power circuit 11, a compensation circuit 12, and a feedback circuit 13; the first terminal of the main power circuit 11 is connected to the first terminal of the feedback circuit 13, and is used to send the output voltage signal into the feedback circuit 13 for sampling; the second terminal of the main power circuit 11 is connected to the second terminal of the feedback circuit 13, and is used to receive the PWM drive signal output by the feedback circuit 13 to control the turn-on and turn-off of the power switching transistor; the third terminal of the main power circuit 11 is connected to the first terminal of the compensation circuit 12, and is used to output the load current detection signal to the compensation circuit 12; the second terminal of the compensation circuit 12 is connected to the third terminal of the feedback circuit 13, and is used to receive the voltage divider feedback signal output by the feedback circuit 13; the third terminal of the compensation circuit 12 is connected to the fourth terminal of the feedback circuit 13, and is used to output the compensation signal after error amplification to the feedback circuit 13; a variable impedance element 12-1 is provided in the compensation circuit 12, and the variable impedance element 12-1 is used to change its resistance value according to the load of the main power circuit.

[0035] The connections between the aforementioned signal terminals form a complete closed-loop control circuit: the main power circuit 11 outputs electrical energy to the load, and simultaneously feeds back its output voltage and load current to the feedback circuit 13 and the compensation circuit 12, respectively; the feedback circuit 13 samples the output voltage and generates a feedback signal, which is then sent to the compensation circuit 12; the compensation circuit 12 generates a compensation signal based on the feedback signal and the load current signal and sends it back to the feedback circuit 13; the feedback circuit 13 generates a PWM drive signal based on the compensation signal and sends it back to the main power circuit 11, thus forming a closed-loop regulation. When the load changes, the resistance value of the variable impedance element 12-1 changes accordingly, dynamically adjusting the transfer function of the compensation circuit 12 to offset the system transfer function drift caused by the load change and achieve frequency stabilization.

[0036] like Figure 2 The diagram shown is a structural schematic of another switching power supply control system provided in an embodiment of this application. Figure 2 exist Figure 1 Based on this, the specific components of the main power circuit 11, the compensation circuit 12, and the feedback circuit 13, as well as the connection relationships between each component, are described in detail.

[0037] The compensation circuit 12 includes a control module 12-2, a digital-to-analog conversion module 12-3, a current-limiting resistor 12-4, and a first diode 12-5.

[0038] The first terminal of the control module 12-2 is connected to the third terminal of the main power circuit 11, and the second terminal of the control module 12-2 is connected to the first terminal of the digital-to-analog conversion module 12-3.

[0039] The second terminal of the digital-to-analog converter module 12-3 is connected to the first terminal of the first diode 12-5, the second terminal of the first diode 12-5 is connected to the first terminal of the current-limiting resistor 12-4, and the second terminal of the current-limiting resistor 12-4 is grounded.

[0040] The aforementioned control module 12-2 is the core controller in the compensation circuit 12 responsible for generating digital control signals based on the load state. Control module 12-2 receives feedback signals from the third terminal of the main power circuit 11, calculates the pole offset of the system transfer function under the current load condition based on these feedback signals, and outputs corresponding digital control signals to the digital-to-analog converter module 12-3. Control module 12-2 can be a microcontroller, a digital signal processor, or a field-programmable gate array (FPGA). The first terminal of control module 12-2 is a signal input terminal, used to receive feedback signals from the third terminal of the main power circuit 11; the second terminal of control module 12-2 is a signal output terminal, used to output digital control signals to the digital-to-analog converter module 12-3. This application embodiment does not limit the type and size of control module 12-2.

[0041] The aforementioned digital-to-analog converter module 12-3 is a key conversion device in the compensation circuit 12 responsible for converting digital signals into analog signals. The digital-to-analog converter module 12-3 converts the digital control signal output from the control module 12-2 into a drive current to drive the first diode 12-5 to emit a light signal of corresponding intensity. It should be noted that the digital-to-analog converter module 12-3 can be a standalone digital-to-analog converter chip or integrated within the control module 12-2 to control the light intensity of the first diode 12-5, thereby achieving fine adjustment of the resistance value of the variable impedance element 12-1. The digital-to-analog converter module 12-3 can also be a DAC (Digital to Analog Converter) chip. The first terminal of the DAC chip is the digital signal input terminal, connected to the second terminal of the control module 12-2, used to receive the digital control signal output from the control module 12-2; the second terminal of the digital-to-analog converter module 12-3 is the analog signal output terminal, connected to the first terminal of the first diode 12-5, used to output the drive current. This application embodiment does not limit the type and size of the digital-to-analog conversion module 12-3.

[0042] The aforementioned current-limiting resistor 12-4 is a current-limiting protection device in the compensation circuit 12 responsible for limiting the current. The current-limiting resistor 12-4 limits the current flowing through the first diode 12-5, preventing damage to the first diode 12-5 due to overcurrent, while ensuring that the first diode 12-5 operates within its rated current range to obtain a stable luminous intensity. The resistance value of the current-limiting resistor 12-4 can be determined based on the rated operating current of the first diode 12-5 and the output voltage of the digital-to-analog converter module 12-3. The current-limiting resistor 12-4 can be a fixed resistor or a variable resistor. The first terminal of the current-limiting resistor 12-4 is connected to the second terminal of the first diode 12-5, and the second terminal of the current-limiting resistor 12-4 is grounded, forming a complete current path in series with the first diode 12-5. This application embodiment does not limit the type and size of the current-limiting resistor 12-4.

[0043] The aforementioned first diode 12-5 is a key electro-optical conversion device in the compensation circuit 12, responsible for converting electrical signals into optical signals. The first diode 12-5 emits a light signal of corresponding intensity when energized, providing a variable light signal to the variable impedance element 12-1, allowing the variable impedance element 12-1 to change its resistance value according to the variable light signal. The first diode 12-5 can be a light-emitting diode, an infrared light-emitting diode, or a laser diode. The luminous intensity of the first diode 12-5 is positively correlated with its driving current; that is, the larger the driving current, the higher the luminous intensity, and the corresponding decrease in the resistance of the photoresistor; the smaller the driving current, the lower the luminous intensity, and the corresponding increase in the resistance of the photoresistor. The first terminal (anode) of the first diode 12-5 is connected to the second terminal of the digital-to-analog converter module 12-3 to receive the analog driving current; the second terminal (cathode) of the first diode 12-5 is connected to the first terminal of the current-limiting resistor 12-4. This application embodiment does not limit the type and size of the first diode 12-5.

[0044] Furthermore, the compensation circuit 12 may also include a first capacitor 12-6. The first terminal of the first capacitor 12-6 is connected to the third terminal of the feedback circuit 13, and the second terminal of the first capacitor 12-6 is connected to the first terminal of the variable impedance element 12-1. The second terminal of the variable impedance element 12-1 is connected to the fourth terminal of the feedback circuit 13.

[0045] The first capacitor 12-6 mentioned above is one of the capacitive components constituting the compensation network in the compensation circuit 12. The first capacitor 12-6 and the variable impedance element 12-1 are connected in series to form an RC feedback branch, which is used to adjust the zero-pole frequency in the feedback circuit. This application embodiment does not limit the type and size of the first capacitor 12-6.

[0046] It should be noted that the first diode 12-5 and the variable impedance element 12-1 adopt a hermetically sealed package structure. This hermetically sealed package structure is used to ensure that the light signal emitted by the first diode 12-5 can be directed to the variable impedance element 12-1, while isolating the variable impedance element 12-1 from interference from external ambient light, ensuring that the resistance change of the variable impedance element 12-1 is only in response to the light signal emitted by the first diode 12-5. The hermetically sealed package structure can be an epoxy resin potting structure, a metal shell package structure, or other package structures that can prevent interference from external ambient light. The type of package structure is not limited in the embodiments of this application.

[0047] Furthermore, the variable impedance element 12-1 can be a photoresistor. A photoresistor has the characteristic that its resistance changes accordingly with changes in light intensity; that is, the stronger the light, the lower the resistance; and the weaker the light, the higher the resistance. The resistance adjustment range of the photoresistor can range from several hundred ohms to several megaohms, which can meet the resistance adjustment requirements of different compensation networks. Because photoresistors have advantages such as low cost, fast response speed, and no polarity requirement, they are suitable for applications requiring continuous resistance adjustment in analog control. The resistance of the photoresistor is negatively correlated with the light intensity; the specific relationship curve depends on the material and manufacturing process of the photoresistor. This application does not limit the specific model or material of the photoresistor.

[0048] In addition, the feedback circuit 13 includes a first sampling resistor 13-1, a second sampling resistor 13-2, a gate driver 13-3, a pulse modulator 13-4, a compensation resistor 13-5, an error amplifier 13-6, and a second capacitor 13-7.

[0049] The first terminal of the first sampling resistor 13-1 is connected to the first terminal of the main power circuit 11.

[0050] The second terminal of the first sampling resistor 13-1 is connected to the first terminal of the compensation resistor 13-5 and the first terminal of the second sampling resistor 13-2, respectively, and the second terminal of the second sampling resistor 13-2 is grounded.

[0051] The second end of the compensation resistor 13-5 is connected to the first end of the first capacitor 12-6, the first end of the second capacitor 13-7, and the first end of the error amplifier 13-6, respectively.

[0052] The first terminal of the pulse modulator 13-4 is connected to the second terminal of the error amplifier 13-6, the second terminal of the variable impedance element 12-1, and the second terminal of the second capacitor 13-7, respectively.

[0053] The second terminal of the pulse modulator 13-4 is connected to the first terminal of the gate driver 13-3, and the second terminal of the gate driver 13-3 is connected to the second terminal of the main power circuit 11.

[0054] The aforementioned first sampling resistor 13-1 is the upper voltage divider resistor in the resistor voltage divider network that forms the feedback circuit 13. The first sampling resistor 13-1 is used in series with the second sampling resistor 13-2 to form a resistor voltage divider network, proportionally attenuating the high voltage output from the main power circuit 11 to an acceptable input voltage range for the error amplifier 13-6. The first terminal of the first sampling resistor 13-1 is connected to the first terminal of the main power circuit 11, and the second terminal of the first sampling resistor 13-1 is connected to the first terminal of the compensation resistor 13-5 and the first terminal of the second sampling resistor 13-2, respectively. This application embodiment does not limit the type and size of the first sampling resistor 13-1.

[0055] The second sampling resistor 13-2 mentioned above is the lower voltage divider resistor in the resistor voltage divider network that forms the feedback circuit 13. The second sampling resistor 13-2 is used in series with the first sampling resistor 13-1 to form a resistor voltage divider network, proportionally attenuating the high voltage output by the main power circuit 11 to an acceptable input voltage range for the error amplifier 13-6. The first terminal of the second sampling resistor 13-2 is connected to the second terminal of the first sampling resistor 13-1 and the first terminal of the compensation resistor 13-5, respectively, and the second terminal of the second sampling resistor 13-2 is grounded. This application embodiment does not limit the type and size of the second sampling resistor 13-2.

[0056] It should be noted that the common node of the first sampling resistor 13-1 and the second sampling resistor 13-2 serves as the feedback output terminal of the feedback circuit 13, providing a voltage-divided feedback signal to the error amplifier 13-6. By adjusting the resistance ratio of the first sampling resistor 13-1 and the second sampling resistor 13-2, the sampling ratio of the output voltage can be set, thereby setting the rated value of the output voltage.

[0057] The gate driver 13-3 described above is the driving device responsible for power amplification in the feedback circuit 13. The gate driver 13-3 receives the PWM signal output from the pulse modulator 13-4 and amplifies its voltage and current to generate sufficient driving capability to drive the power switch 11-2 in the main power circuit 11. The first terminal of the gate driver 13-3 is connected to the second terminal of the pulse modulator 13-4, and the second terminal of the gate driver 13-3 is connected to the second terminal of the main power circuit 11. The gate driver 13-3 can be a gate driver chip or a discrete driving circuit, such as a driving chip with undervoltage lockout and overcurrent protection functions. This application embodiment does not limit the type and size of the gate driver 13-3.

[0058] The pulse modulator 13-4 described above is the core control device responsible for pulse width modulation in the feedback circuit 13. The pulse modulator 13-4 receives the error amplification signal output from the error amplifier 13-6 and generates a pulse width modulation signal with a corresponding duty cycle based on the amplitude of this signal. The first terminal of the pulse modulator 13-4 is connected to the second terminal of the error amplifier 13-6, the second terminal of the variable impedance element 12-1, and the second terminal of the second capacitor 13-7, respectively. The second terminal of the pulse modulator 13-4 is connected to the first terminal of the gate driver 13-3. A suitable pulse modulator, such as UC3842 or TL494, can be selected according to the switching frequency and modulation requirements. This application embodiment does not limit the type and size of the pulse modulator 13-4.

[0059] The aforementioned compensation resistor 13-5 is one of the resistive components constituting the compensation network in the feedback circuit 13. Compensation resistor 13-5, together with the first capacitor 12-6, the second capacitor 13-7, and the variable impedance element 12-1, forms the compensation network of the error amplifier 13-6, used to adjust the zero-pole frequency of the control loop. The first terminal of compensation resistor 13-5 is connected to the second terminal of the first sampling resistor 13-1 and the first terminal of the second sampling resistor 13-2, respectively. The second terminal of compensation resistor 13-5 is connected to the first terminal of the first capacitor 12-6, the first terminal of the second capacitor 13-7, and the first terminal of the error amplifier 13-6, respectively. A resistor with a suitable resistance value can be selected as compensation resistor 13-5 according to the operating frequency of the switching power supply and the compensation requirements. This application embodiment does not limit the type and size of compensation resistor 13-5.

[0060] The aforementioned error amplifier 13-6 is the core amplification device in the feedback circuit 13, responsible for signal amplification and error processing. Error amplifier 13-6 compares the feedback signal with a reference voltage and amplifies the difference (i.e., the error signal) before outputting it to pulse modulator 13-4. The first terminal of error amplifier 13-6 is connected to the second terminal of compensation resistor 13-5, and the second terminal of error amplifier 13-6 is connected to the first terminal of pulse modulator 13-4, the second terminal of variable impedance element 12-1, and the second terminal of second capacitor 13-7, respectively. The non-inverting input terminal of error amplifier 13-6 is connected to a reference voltage source to set the reference value of the output voltage. This application embodiment does not limit the type and size of error amplifier 13-6.

[0061] The aforementioned second capacitor 13-7 is one of the capacitive components constituting the compensation network in the feedback circuit 13. The second capacitor 13-7, together with the compensation resistor 13-5, the first capacitor 12-6, and the variable impedance element 12-1, forms the compensation network of the error amplifier 13-6, used to adjust the zero-pole frequency of the control loop. The first terminal of the second capacitor 13-7 is connected to the second terminal of the compensation resistor 13-5 and the first terminal of the error amplifier 13-6. The second terminal of the second capacitor 13-7 is connected to the second terminal of the error amplifier 13-6, the second terminal of the variable impedance element 12-1, and the first terminal of the pulse modulator 13-4, respectively. This application does not limit the type and size of the second capacitor 13-7; for example, the second capacitor 13-7 can be a ceramic capacitor or a film capacitor.

[0062] It should be noted that the compensation resistor 13-5, the first capacitor 12-6, the second capacitor 13-7, and the variable impedance element 12-1 together constitute the compensation network of the Type II error amplifier. Specifically, the compensation resistor 13-5 and the second capacitor 13-7 are connected in series between the inverting input and output of the error amplifier 13-6, forming the main feedback branch; the first capacitor 12-6 and the variable impedance element 12-1 are connected in series and in parallel with the second capacitor 13-7, forming the auxiliary feedback branch. When the resistance of the variable impedance element 12-1 changes with the load, the impedance of the auxiliary feedback branch changes accordingly, thereby changing the zero-pole frequency of the compensation network and achieving dynamic adjustment of the transfer function. The compensation network structure in this embodiment is illustrated using a Type II error amplifier as an example, but this application is not limited to this. In other possible embodiments, the compensation network can also adopt a Type III error amplifier structure, that is, adding a resistor-capacitor network to the above-mentioned Type II compensation network to provide additional phase lead compensation, thereby obtaining a wider control bandwidth and higher stability margin.

[0063] In addition, the main power circuit 11 may include a second diode 11-1, a power switch 11-2, a flyback transformer 11-3, an energy storage capacitor 11-4, and a parasitic resistor 11-5.

[0064] The first terminal of the flyback transformer 11-3 is connected to the first terminal of the second diode 11-1, and the second terminal of the second diode 11-1 is connected to the first terminal of the energy storage capacitor 11-4 and the first terminal of the first sampling resistor 13-1, respectively.

[0065] The second terminal of the flyback transformer 11-3 is connected to the second terminal of the parasitic resistor 11-5 and the second terminal of the second sampling resistor 13-2, and then grounded together.

[0066] The second terminal of the energy storage capacitor 11-4 is connected to the first terminal of the parasitic resistor 11-5.

[0067] The first terminal of the power switch 11-2 is connected to the third terminal of the flyback transformer 11-3, the second terminal of the power switch 11-2 is connected to the second terminal of the gate driver 13-3, and the third terminal of the power switch 11-2 is grounded.

[0068] The fourth terminal of the flyback transformer 11-3 is connected to the DC bus.

[0069] The aforementioned second diode 11-1 is a key power device responsible for rectification in the main power circuit 11. The second diode 11-1 is used to rectify the high-frequency pulse voltage output from the secondary winding of the flyback transformer 11-3 into a pulsating DC voltage. The first terminal (anode) of the second diode 11-1 is connected to the first terminal (first terminal of the secondary winding) of the flyback transformer 11-3, and the second terminal (cathode) of the second diode 11-1 is connected to the first terminal of the energy storage capacitor 11-4 and the first terminal of the first sampling resistor 13-1, respectively. This application embodiment does not limit the type and size of the second diode 11-1.

[0070] The aforementioned power switch 11-2 is the core power device responsible for high-frequency switching in the main power circuit 11. Power switch 11-2 is used to alternately turn on and off under the control of the PWM drive signal, converting the DC voltage input from the DC bus into a high-frequency pulse voltage, which is applied to the primary winding of the flyback transformer 11-3. The first terminal (collector / drain) of power switch 11-2 is connected to the third terminal (second terminal of the primary winding) of flyback transformer 11-3, the second terminal (gate / control terminal) of power switch 11-2 is connected to the second terminal of gate driver 13-3, and the third terminal (emitter / source) of power switch 11-2 is grounded. This application does not limit the type and size of power switch 11-2.

[0071] The aforementioned flyback transformer 11-3 is the core magnetic component in the main power circuit 11, responsible for voltage transformation, electrical isolation, and energy storage. The flyback transformer 11-3 stores energy when the power switch 11-2 is turned on and releases the stored energy to the load side when the power switch 11-2 is turned off, achieving electrical isolation and voltage transformation between input and output. The flyback transformer 11-3 has a primary winding and a secondary winding. The primary winding receives input electrical energy, and the secondary winding outputs electrical energy. The fourth terminal (first terminal of the primary winding) of the flyback transformer 11-3 is connected to the DC bus; the third terminal (second terminal of the primary winding) is connected to the first terminal of the power switch 11-2; the first terminal (first terminal of the secondary winding) of the flyback transformer 11-3 is connected to the first terminal (anode) of the second diode 11-1; and the second terminal (second terminal of the secondary winding) of the flyback transformer 11-3 is connected to the output ground. This application does not limit the type and size of the flyback transformer 11-3.

[0072] The aforementioned energy storage capacitor 11-4 is an energy storage element responsible for filtering and smoothing in the main power circuit 11. Energy storage capacitor 11-4 is used to smooth and filter the pulsating DC voltage after rectification by the second diode 11-1 to output a stable DC voltage. The first terminal of energy storage capacitor 11-4 is connected to the second terminal (cathode) of the second diode 11-1 and the first terminal of the first sampling resistor 13-1, respectively. The second terminal of energy storage capacitor 11-4 is connected to the first terminal of the parasitic resistor 11-5. This application embodiment does not limit the type and size of energy storage capacitor 11-4.

[0073] The parasitic resistance 11-5 described above is the equivalent series resistance characterizing the impedance of the energy storage capacitor 11-4. The parasitic resistance 11-5 is not an independently mounted physical component, but rather an inherent parasitic parameter of the energy storage capacitor 11-4, and its resistance value depends on the material, structure, and manufacturing process of the energy storage capacitor 11-4. The presence of the parasitic resistance 11-5 affects the filtering effect of the energy storage capacitor 11-4 and the output impedance characteristics of the system. The first terminal of the parasitic resistance 11-5 is connected to the second terminal of the energy storage capacitor 11-4, and the second terminal of the parasitic resistance 11-5 is connected to the output ground (i.e., the common node of the second terminal of the flyback transformer 11-3, the second terminal of the second sampling resistor 13-2, and the second terminal of the third sampling resistor 11-7). This application does not limit the type and size of the parasitic resistance 11-5.

[0074] Correspondingly, the main power circuit 11 may also include a load module 11-6 and a third sampling resistor 11-7.

[0075] The first terminal of the load module 11-6 is connected to the first terminal of the first sampling resistor 13-1 and the first terminal of the energy storage capacitor 11-4, respectively.

[0076] The second terminal of the load module 11-6 is connected to the first terminal of the control module 12-2 and the first terminal of the third sampling resistor 11-7, respectively.

[0077] The second terminal of the third sampling resistor 11-7 is connected to the second terminal of the flyback transformer 11-3, the second terminal of the parasitic resistor 11-5, and the second terminal of the second sampling resistor 13-2, respectively.

[0078] The aforementioned load module 11-6 is a load element in the main power circuit 11 used to simulate actual electrical equipment. The load module 11-6 consumes electrical energy and represents the actual load of the switching power supply system. Its resistance change is used to simulate the dynamic switching of load conditions during the operation of electronic equipment. The first terminal of the load module 11-6 is connected to the first terminal of the first sampling resistor 13-1 and the first terminal of the energy storage capacitor 11-4, respectively. The second terminal of the load module 11-6 is connected to the first terminal of the control module 12-2 and the first terminal of the third sampling resistor 11-7, respectively. This embodiment does not limit the type or size of the load module 11-6.

[0079] The aforementioned third sampling resistor 11-7 is a sampling element used for current sampling in the main power circuit 11. The third sampling resistor 11-7 is connected in series with the load module 11-6, and obtains the current signal flowing through the load module 11-6 by detecting the voltage drop across it. This current signal is used to characterize the load state of the main power circuit 11. The first terminal of the third sampling resistor 11-7 is connected to the second terminal of the load module 11-6 and the first terminal of the control module 12-2, respectively. The second terminal of the third sampling resistor 11-7 is connected to the second terminal of the flyback transformer 11-3, the second terminal of the parasitic resistor 11-5, and the second terminal of the second sampling resistor 13-2 (i.e., connected to the output ground). This application embodiment does not limit the type and size of the third sampling resistor 11-7.

[0080] It should be noted that the first terminal of the control module 12-2 is connected to the common node of the second terminal of the load module 11-6 and the first terminal of the third sampling resistor 11-7, for detecting the potential of this node. Since the second terminal of the third sampling resistor 11-7 is connected to the output ground, the current flowing through the third sampling resistor 11-7 is equal to the current flowing through the load module 11-6. Therefore, the voltage drop across the third sampling resistor 11-7 is proportional to the load current. By detecting the potential of this node and combining it with the resistance value of the third sampling resistor 11-7, the control module 12-2 can calculate the current load current value, thereby obtaining the load status information of the main power circuit 11. When the resistance of the load module 11-6 changes, the current flowing through the load module 11-6 and the third sampling resistor 11-7 changes accordingly. The control module 12-2 can sense the load change by detecting the change in voltage drop across the third sampling resistor 11-7, and then generate a corresponding digital control signal based on the change to drive the digital-to-analog converter module 12-3 and the first diode 12-5 to adjust the resistance of the variable impedance element 12-1, thereby realizing the dynamic adjustment of the transfer function of the compensation network.

[0081] Based on the above Figure 1 , Figure 2 The hardware architecture of the switching power supply control system is described in this application embodiment, which also provides a control method for the switching power supply control system, such as... Figure 3 The diagram shown is a schematic representation of the implementation flow of a control method for a switching power supply control system provided in this application embodiment, which may specifically include the following steps: S301, obtains the feedback signal from the main power circuit.

[0082] In this embodiment of the application, the feedback signal of the main power circuit can be obtained, i.e., the above-mentioned Figure 1 The feedback signal of the main power circuit 11. The feedback signal refers to the detection signal that characterizes the current load current of the main power circuit (i.e., Figure 2 The current signal is transmitted from the third sampling resistor 11-7 to the control module 12-2.

[0083] As for the specific method of obtaining the feedback signal from the main power circuit, it can be explained below. Figure 4 The process shown will be explained in detail here.

[0084] S302 determines the drive current based on the feedback signal, so as to change the resistance value of the variable impedance element by the drive current.

[0085] In this embodiment, the drive current can be determined based on the feedback signal, so as to change the variable impedance element (i.e., the one described above) through the drive current. Figure 1 The resistance value of the variable impedance element 12-1. Specifically, Figure 2 The control module 12-2 determines the output level based on the feedback signal, and the digital-to-analog conversion module 12-3 determines the drive current based on its output level to adjust the brightness of the first diode 12-5, thereby changing the resistance of the variable impedance element 12-1.

[0086] Specifically, determining the drive current based on the feedback signal may include the following steps: (1) Determine the load resistance based on the feedback signal: Obtain the load current I_load from the feedback signal, since the switching power supply control system (i.e. Figure 2 The output voltage V_out of the switching power supply control system 10 is maintained constant by the voltage regulation loop. The control module 12-2 can calculate the current load resistance (i.e., the current load resistance) according to Ohm's law. Figure 2 (R7 = V_out / I_load) of medium load module 11-6

[0087] (2) Calculate the current main power pole frequency based on the load resistance: e.g. Figure 1 The output filtering stage of the main power circuit 11 shown consists of... Figure 2The energy storage capacitor 11-4 (capacitance value C1) and the load resistor R7 constitute a component that introduces a principal power pole F_p into the system transfer function. When the load resistor R7 changes, the principal power pole F_p shifts accordingly. The control module 12-2 can calculate the principal power pole frequency F_p = 1 / (2π×R7×C1) under the current load condition according to the pole formula.

[0088] (3) Solving for the target photoresistor resistance: The switching power supply control system 10 has an optimal target crossover frequency F_cross(set) (fixed design value) during design. At this crossover frequency, the system has sufficient phase margin to ensure stable operation. The system's open-loop transfer function is determined by the main power pole frequency F_p and the zeros and poles of the compensation network. The control module 12-2 has a built-in closed-loop matching algorithm. Based on the main power pole frequency F_p calculated in real time, the required compensation zero-pole frequency is deduced, and then the target resistance value R2(target) of the photoresistor is solved by using the compensation zero-pole formula.

[0089] As an optional embodiment, such as Figure 2 As shown, the compensation zero and pole frequencies of the Type II compensation network are jointly determined by the photoresistor R2 (resistance value R2), the first capacitor C2 (capacitance value C2), and the second capacitor C3 (capacitance value C3): Compensation zero frequency: F_z1=1 / (2π×R2×C2); Compensation pole frequency: F_p1=1 / (2π×R2×C3).

[0090] By transforming the above formula, we can obtain the target resistance value of the photoresistor: R2(target)=1 / (2π×F_z1(target)×C2) or R2(target)=1 / (2π×F_p1(target)×C3).

[0091] Wherein, F_z1(target) and F_p1(target) are the required compensated zero-pole frequencies determined by control module 12-2 based on the current main power pole F_p and the target crossover frequency F_cross(set).

[0092] (4) Calculate the target driving current based on the resistance value of the target photoresistor.

[0093] like Figure 2 As shown, the photoresistor (i.e., variable impedance element 12-1) and the first diode 12-5 adopt a hermetically sealed package structure. A calibration curve exists between them, indicating that the light intensity is directly proportional to the driving current of the first diode 12-5, while the photoresistor resistance is negatively correlated with the light intensity (monotonically decreasing). This calibration curve is obtained through experimental measurement at the factory and is pre-set in the control module 12-2 as a fitting function.

[0094] After obtaining the target photoresistor resistance value R2(target), the control module 12-2 can use a preset fitting function to inversely calculate the required driving current: I_LED(target) = f (-1) (R2(target)), where f is the calibration fitting function (monotonically decreasing) between the resistance of the photoresistor and the driving current. (-1) It is its inverse function.

[0095] (5) Calculate the DAC digital quantity based on the target drive current: The drive current from the output of the digital-to-analog converter module 12-3 to the first diode 12-5 is determined by the output voltage V_DAC of the digital-to-analog converter module 12-3. The first diode 12-5 has a forward voltage drop V_D (which is basically constant), and the resistance of the current-limiting resistor 12-4 is R6. According to Ohm's law: I_LED(target)=(V_DAC-V_D) / R6, the target output voltage V_DAC(target) of the digital-to-analog converter module 12-3 is obtained as V_DAC(target)=I_LED(target)×R6+V_D.

[0096] Furthermore, the output voltage of the digital-to-analog converter module 12-3 is determined by the received digital quantity D and the full-scale reference voltage V_REF. For example, if the digital-to-analog converter module 12-3 uses an 8-bit DAC with a digital quantity range of D∈[0,255], then the output relationship is: V_DAC=V_REF×(D / 256). Therefore, the control module 12-2 can calculate the required digital quantity D based on the target output voltage V_DAC(target): D=(V_DAC(target) / V_REF)×256.

[0097] If the calculated D > 255, the limiting is D = 255; if D < 0, the limiting is D = 0. The control module 12-2 outputs the final calculated 8-bit binary digital level D to the digital-to-analog converter module 12-3. The digital-to-analog converter module 12-3 outputs the analog voltage V_DAC corresponding to D, which is then current-limited by the current-limiting resistor 12-4 and drives the first diode 12-5 to emit a light signal of corresponding intensity. The variable impedance element 12-1 (photoresistor) changes its resistance with the light intensity under the illumination of the light signal, thereby realizing the dynamic adjustment of the transfer function of the compensation network.

[0098] Based on the above description of the technical solution provided in the embodiments of this application, feedback signals from the main power circuit are obtained. The drive current is determined based on the feedback signals, and the resistance value of the variable impedance element is changed by the drive current, thereby enabling the switching power supply control system to maintain stable crossover frequency and sufficient phase margin under different load conditions.

[0099] like Figure 4The diagram shown is a schematic representation of the implementation flow of a feedback signal acquisition method provided in an embodiment of this application. Figure 4 exist Figure 3 Based on this, a detailed description is given of how to obtain the feedback signal of the main power circuit, which may include the following: S401 collects the voltage value of the third sampling resistor in the main power circuit.

[0100] In this embodiment, the voltage value of the third sampling resistor in the main power circuit is collected, that is, the voltage value of the aforementioned resistor is collected. Figure 2 The voltage value of the third sampling resistor 11-7 in the main power circuit 11. The third sampling resistor 11-7 is connected in series between the low voltage side of the load module 11-6 and the output ground. The current flowing through this sampling resistor is exactly the same as the load operating current. The control module 12-2 can collect the voltage value of the third sampling resistor in the main power circuit.

[0101] S402 determines the feedback signal of the main power circuit 11 based on the voltage value and the resistance value of the third sampling resistor.

[0102] In this embodiment, the ratio of the voltage value to the resistance value of the third sampling resistor can be used as the real-time load current signal, and this current signal can be used as a feedback signal characterizing the operating state of the main power circuit. That is, the control module 12-2 determines the ratio of the voltage value V_R8 to the resistance value R8, I_load=V_R8 / R8, as the real-time load current signal based on the voltage value V_R8 across the third sampling resistor 11-7 acquired in step S401 and the known resistance value R8 of the third sampling resistor 11-7, and uses this current signal as a feedback signal characterizing the operating state of the main power circuit 11, and uses it as the input quantity for the subsequent closed-loop matching calculation of the control module 12-2.

[0103] Furthermore, in this application embodiment, the control method of the switching power supply control system provided in this application embodiment is described with reference to specific examples: like Figure 5 The diagram shown is a schematic representation of the implementation flow of a control method for another switching power supply control system provided in this application embodiment, which may specifically include the following: Step 1: Read the electrical signal of the sampling resistor.

[0104] In the embodiments of this application, Figure 2The control module 12-2 can read the voltage signal (i.e., the sampling resistor electrical signal) across the third sampling resistor 11-7 in real time through its first terminal. The third sampling resistor 11-7 is connected in series between the low-voltage side of the load module 11-6 and the output ground. The current flowing through the third sampling resistor 11-7 is equal to the load current flowing through the load module 11-6. Therefore, the voltage signal across the third sampling resistor 11-7 can reflect the magnitude of the load current of the main power circuit 11 in real time. When the resistance of the load module 11-6 changes, the voltage signal changes accordingly.

[0105] Step 2: Determine whether the electrical signal of the sampling resistor has changed.

[0106] In this embodiment, the control module 12-2 determines whether the value of the sampling resistor signal read in step 1 has changed compared to the previous sampling period. If the determination result is yes (i.e., the sampling resistor signal has changed), then step 3 is executed; if the determination result is no (i.e., the sampling resistor signal has not changed and the load state is stable), then step S1 is returned to continue reading the sampling resistor signal, maintaining the current state unchanged. Through the above determination mechanism, false triggering caused by signal fluctuations or noise can be avoided, while reducing unnecessary computational overhead and lowering system power consumption.

[0107] Step 3, MCU function calculation.

[0108] In this embodiment, when the control module 12-2 determines that the sampling signal has changed, it triggers the MCU function calculation process. The core of this calculation process is to convert the load change information into the resistance adjustment amount of the variable impedance element 12-1, so as to achieve dynamic matching of the transfer function of the compensation network.

[0109] The core principle is that different load conditions change the system's transfer function, causing the poles of the RC filter's transfer function to shift, which in turn causes the system's crossover frequency to drift, leading to stability problems. This application's embodiment utilizes a light-emitting diode (LED)... Figure 2 The light-emitting characteristics of the first diode (12-5) and the photoresistor (i.e. Figure 2 The light intensity modulation characteristics of the variable impedance element 12-1, and the dynamic adjustment error amplifier (i.e. Figure 2 The pole frequency of the transfer function of the error amplifier (13-6) enables the system to automatically optimize the control loop parameters under different load conditions, ensure stable crossover frequency, and maintain sufficient phase and gain margins, thereby ensuring the overall stability of the system.

[0110] The specific process for calculating the above MCU function includes the following steps: First, control module 12-2 calculates the load current I_load = V_R8 / R8 using Ohm's law, based on the voltage value V_R8 of the third sampling resistor and the known resistance R8 of the third sampling resistor 11-7. Since the output voltage V_out of the switching power supply control system 10 is kept constant by the voltage regulation loop, control module 12-2 further calculates the current load resistance R7 = V_out / I_load = (V_out × R8) / V_R8 according to Ohm's law.

[0111] Secondly, based on the calculated load resistance R7 and the capacitance value C1 of the energy storage capacitor 11-4, control module 12-2 calculates the main power pole frequency F_p = 1 / (2π×R7×C1) = V_R8 / (2π×V_out×R8×C1) under the current load condition. Based on the real-time calculated main power pole frequency F_p and the system's preset optimal target crossover frequency F_cross(set), control module 12-2 reverse-engineers the required compensation zero-pole frequency, and then uses the compensation zero-pole formula to solve for the target resistance value of the photoresistor R2(target) = 1 / (2π×F_z1(target)×C2), where F_z1(target) is the required target compensation zero-point frequency and C2 is the capacitance value of the first capacitor.

[0112] Finally, based on the target photoresistor resistance value R2(target), the control module 12-2 uses a preset calibration fitting function between the photoresistor resistance value and the driving current to inversely calculate the required LED driving current I_LED(target) = f. (-1) (R2(target)). Control module 12-2 then calculates the target DAC output voltage V_DAC(target) = I_LED(target) × R6 + V_D based on the drive current.

[0113] R6 is the resistance of the current limiting resistor, V_D is the forward voltage drop of the LED, and finally the 8-bit DAC digital value D is calculated as D=(V_DAC(target) / V_REF)×256, and then the amplitude is limited (if D>255, the amplitude is limited to 255; if D<0, the amplitude is limited to 0).

[0114] Step 4: Adjust the DAC input value.

[0115] In this embodiment, the control module 12-2 outputs the 8-bit binary digital level D calculated in step 3 to the digital-to-analog converter module 12-3 (DAC chip). The DAC module 12-3 outputs the corresponding analog voltage V_DAC based on the received digital value D. After current limiting by the current-limiting resistor 12-4, it drives the first diode 12-5 to emit a light signal of corresponding intensity. Under the illumination of the light signal from the first diode 12-5, the resistance of the variable impedance element 12-1 (photoresistor) changes with the light intensity; that is, the stronger the illumination, the smaller the resistance; the weaker the illumination, the larger the resistance. The change in the photoresistor's resistance alters the RC time constant of the compensation network, thereby adjusting the zero-pole frequency of the transfer function of the error amplifier 13-6, matching the transfer function of the compensation network with the current load conditions, and achieving frequency stabilization. Subsequently, the process returns to step 1 above, continues reading the sampling resistor signal, and enters the next monitoring and adjustment cycle.

[0116] Specifically, the switching power supply control system consists of a main power circuit, a feedback circuit, and a compensation network. In the compensation network, the traditional fixed-value resistor is replaced by a photoresistor (i.e., variable impedance element 12-1), and the photoresistor and the light-emitting diode (i.e., the first diode 12-5) are encapsulated in a sealed package to prevent interference from ambient light and ensure that the resistance change of the photoresistor only responds to the control light signal emitted by the light-emitting diode. When the load changes, the sampling resistor (i.e., the third sampling resistor 11-7) collects the load current signal and transmits it to the control module 12-2 (MCU) for real-time calculation. The control module 12-2 outputs a digital level signal to the digital-to-analog converter module 12-3 (DAC chip), which precisely adjusts the drive current of the light-emitting diode after digital-to-analog conversion, thereby changing the resistance value of the photoresistor. Ultimately, this achieves dynamic adjustment of the transfer function of the loop compensation circuit, effectively suppressing system instability caused by load changes.

[0117] Through the aforementioned cyclic monitoring and dynamic adjustment mechanism, the switching power supply control system provided in this application embodiment can track load changes in real time and respond quickly when the load changes, automatically adjusting the compensation network parameters to ensure that the system maintains stable cross-frequency and sufficient phase margin under different load conditions, thereby guaranteeing the dynamic response performance and loop stability of the switching power supply control system. This control method does not rely on complex digital control algorithms; it only utilizes the MCU's analog-to-digital conversion control and the physical characteristics of the photoresistor to achieve adaptive adjustment. It has advantages such as simple implementation, low cost, and rapid response, and is particularly suitable for mass application scenarios of small and medium power analog switching power supplies.

[0118] The embodiments of this application can achieve dynamic adjustment of system stability through the physical characteristics of photoresistors, and have the advantages of optocoupler characteristics, simple structure, and low cost.

[0119] It should be noted that the compensation circuit in the above embodiments is illustrated using a Type II error amplifier as an example, but this application is not limited thereto. In practical applications, the technical solution of this application is also applicable to a Type III error amplifier, that is, by adding a resistor-capacitor network to the Type II compensation network to provide additional phase lead compensation, the zero-pole frequency of the compensation circuit transfer function can also be matched with the system. Those skilled in the art, inspired by the above embodiments, can apply it to the Type III error amplifier structure without creative effort, and it also falls within the protection scope of this application.

[0120] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0121] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0122] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A switching power supply control system, characterized in that, The switching power supply control system includes: a main power circuit, a compensation circuit, and a feedback circuit; The first terminal of the main power circuit is connected to the first terminal of the feedback circuit, and the second terminal of the main power circuit is connected to the second terminal of the feedback circuit. The third terminal of the main power circuit is connected to the first terminal of the compensation circuit; The second terminal of the compensation circuit is connected to the third terminal of the feedback circuit; the third terminal of the compensation circuit is connected to the fourth terminal of the feedback circuit. The compensation circuit is equipped with a variable impedance element, which is used to change its resistance value according to the load of the main power circuit.

2. The switching power supply control system according to claim 1, characterized in that, The compensation circuit includes a control module, a digital-to-analog converter module, a current-limiting resistor, and a first diode; The first terminal of the control module is connected to the third terminal of the main power circuit, and the second terminal of the control module is connected to the first terminal of the digital-to-analog converter module. The second terminal of the digital-to-analog converter module is connected to the first terminal of the first diode, the second terminal of the first diode is connected to the first terminal of the current-limiting resistor, and the second terminal of the current-limiting resistor is grounded.

3. The switching power supply control system according to claim 2, characterized in that, The compensation circuit includes a first capacitor; The first terminal of the first capacitor is connected to the third terminal of the feedback circuit, and the second terminal of the first capacitor is connected to the first terminal of the variable impedance element. The second terminal of the variable impedance element is connected to the fourth terminal of the feedback circuit.

4. The switching power supply control system according to claim 2, characterized in that, The first diode and the variable impedance element are encapsulated in a hermetically sealed package.

5. The switching power supply control system according to claim 4, characterized in that, The variable impedance element is a photoresistor.

6. The switching power supply control system according to claim 3, characterized in that, The feedback circuit includes a first sampling resistor, a second sampling resistor, a gate driver, a pulse modulator, a compensation resistor, an error amplifier, and a second capacitor. The first end of the first sampling resistor is connected to the first end of the main power circuit; The second end of the first sampling resistor is connected to the first end of the compensation resistor and the first end of the second sampling resistor, respectively, and the second end of the second sampling resistor is grounded; The second end of the compensation resistor is connected to the first end of the first capacitor, the first end of the second capacitor, and the first end of the error amplifier, respectively. The first terminal of the pulse modulator is connected to the second terminal of the error amplifier, the second terminal of the variable impedance element, and the second terminal of the second capacitor, respectively. The second terminal of the pulse modulator is connected to the first terminal of the gate driver, and the second terminal of the gate driver is connected to the second terminal of the main power circuit.

7. The switching power supply control system according to claim 6, characterized in that, The main power circuit includes a second diode, a power switch, a flyback transformer, an energy storage capacitor, and a parasitic resistor. The first terminal of the flyback transformer is connected to the first terminal of the second diode, and the second terminal of the second diode is connected to the first terminal of the energy storage capacitor and the first terminal of the first sampling resistor, respectively. The second terminal of the flyback transformer is connected to the second terminal of the parasitic resistor and the second terminal of the second sampling resistor, respectively, and then grounded together. The second terminal of the energy storage capacitor is connected to the first terminal of the parasitic resistor; The first terminal of the power switch is connected to the third terminal of the flyback transformer, the second terminal of the power switch is connected to the second terminal of the gate driver, and the third terminal of the power switch is grounded. The fourth terminal of the flyback transformer is connected to the DC bus.

8. The switching power supply control system according to claim 7, characterized in that, The main power circuit includes a load module and a third sampling resistor; The first end of the load module is connected to the first end of the first sampling resistor and the first end of the energy storage capacitor, respectively. The second end of the load module is connected to the first end of the control module and the first end of the third sampling resistor, respectively. The second terminal of the third sampling resistor is connected to the second terminal of the flyback transformer, the second terminal of the parasitic resistor, and the second terminal of the second sampling resistor, respectively.

9. A control method for a switching power supply control system, characterized in that, The method, applied to the switching power supply control system as described in any one of claims 1 to 8, comprises: Obtain the feedback signal from the main power circuit; The drive current is determined based on the feedback signal, so as to change the resistance value of the variable impedance element.

10. The method according to claim 9, characterized in that, The method of obtaining the feedback signal from the main power circuit includes: Collect the voltage value of the third sampling resistor in the main power circuit; The feedback signal of the main power circuit is determined based on the voltage value and the resistance value of the third sampling resistor.

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