A device for improving output voltage accuracy and its control method, and a switching power supply.

Abstract

This invention provides an output voltage accuracy improvement device and its control method, as well as a switching power supply, relating to the field of switching power supply technology. The output voltage accuracy improvement device includes: a sampling module for acquiring the output voltage of the main power circuit of the switching power supply; an error detection module connected to the sampling module for determining the difference between a first reference voltage and the output voltage; a proportional-integral (PI) module connected to the error detection module; a pulse width modulation (PWM) wave generation module connected to the output terminal of the PI module; a pull-down resistor and a pull-down transistor, wherein the base of the pull-down transistor is connected to the output terminal of the PWM wave generation module, the collector of the pull-down transistor is connected to the first terminal of the pull-down resistor, the emitter of the pull-down transistor is connected to the second terminal of the power supply, and the second terminal of the pull-down resistor is connected to the input terminal of a voltage feedback type switching voltage controller. This invention can effectively improve the output voltage accuracy of a switching power supply without significantly increasing development workload and cost.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, and more specifically, to an output voltage accuracy improvement device and its control method, and a switching power supply. Background Technology

[0002] A switching power supply is a power device that uses high-frequency switching technology to efficiently convert electrical energy into the required voltage or current. It typically uses a closed-loop feedback circuit to regulate the output voltage. This feedback circuit generally includes an output voltage sampling circuit and a switching power supply controller. The accuracy of the output voltage regulation depends primarily on two key factors: the sampling accuracy of the voltage sampling circuit and the accuracy of the internal reference voltage of the switching power supply controller.

[0003] However, the reference voltage inside the switching power supply controller is usually integrated into the chip as an inherent parameter, and its accuracy is fixed during device manufacturing, making it difficult to adjust during application. When the accuracy of this reference voltage cannot meet the output voltage accuracy requirements of a specific application scenario, existing solutions often struggle to achieve accuracy compensation. For example, if the accuracy of the controller's built-in reference voltage is ±1%, while the switching power supply system requires an output voltage accuracy of ±0.1%, even if the sampling network accuracy is high enough, the entire feedback control loop will still be unable to achieve the required output accuracy due to the error of the reference voltage. In this case, to meet higher accuracy output requirements, related technologies typically require redesigning or customizing a dedicated controller, which not only results in a long development cycle but also significantly increases the development workload and costs.

[0004] Therefore, there is an urgent need for a technical solution that can improve the output voltage accuracy of switching power supplies without replacing the controller. Summary of the Invention

[0005] The problem solved by this invention is how to effectively improve the output voltage accuracy of a switching power supply without significantly increasing development workload and cost.

[0006] To address the aforementioned problems, this invention provides an output voltage accuracy improvement device and its control method, as well as a switching power supply.

[0007] In a first aspect, the present invention provides an output voltage accuracy improvement device, comprising:

[0008] A sampling module, the input terminal of which is used to obtain the output voltage of the main power circuit of the switching power supply, the input terminal of which is connected to the first terminal of the power supply;

[0009] An error detection module is provided, the input of which is connected to the output of the sampling module. The error detection module is used to determine the difference between a first reference voltage and the output voltage. The accuracy of the first reference voltage is configured to ensure that the output voltage meets a preset accuracy requirement.

[0010] A proportional-integral module, wherein the input of the proportional-integral module is connected to the output of the error detection module;

[0011] A pulse width modulation wave generation module, wherein the input terminal of the pulse width modulation wave generation module is connected to the output terminal of the proportional-integral module;

[0012] The system includes a pull-down resistor and a pull-down transistor. The base of the pull-down transistor is connected to the output terminal of the pulse width modulation wave generation module. The collector of the pull-down transistor is connected to the first terminal of the pull-down resistor. The emitter of the pull-down transistor is configured to be connected to the second terminal of the power supply. The second terminal of the pull-down resistor is configured to be connected to the input terminal of a voltage feedback type switching voltage controller. The input terminal of the voltage feedback type switching voltage controller is also connected to the output terminal of the main power circuit of the switching power supply through a voltage sampling circuit. The output terminal of the voltage feedback type switching voltage controller is connected to the control terminal of the main power circuit of the switching power supply.

[0013] Optionally, the sampling accuracy of the sampling module is configured to ensure that the output voltage meets a preset accuracy requirement.

[0014] Optionally, the sampling module includes a first resistor voltage divider sampling circuit, the first end of which serves as the input terminal of the sampling module and is connected to the output terminal of the main power circuit of the switching power supply, the second end of which serves as the output terminal of the sampling module and is connected to the input terminal of the error detection module, and the third end of which is connected to the second terminal of the power supply.

[0015] Optionally, the first resistor voltage divider sampling circuit includes an upper voltage divider resistor and a lower voltage divider resistor. The first end of the upper voltage divider resistor serves as the first end of the first resistor voltage divider sampling circuit and is connected to the output end of the main power circuit of the switching power supply. The second end of the upper voltage divider resistor is connected to the first end of the lower voltage divider resistor to form a first connection point. The first connection point serves as the second end of the first resistor voltage divider sampling circuit and is connected to the input end of the error detection module. The second end of the lower voltage divider resistor serves as the third end of the first resistor voltage divider sampling circuit and is connected to the second end of the power supply.

[0016] Optionally, the accuracy of the upper voltage divider resistor and the lower voltage divider resistor is configured to ensure that the output voltage meets a preset accuracy requirement.

[0017] In a second aspect, the present invention provides a switching power supply, including a power supply, a main power circuit of the switching power supply, a voltage feedback type switching voltage controller, a voltage sampling circuit, and an output voltage accuracy improvement device as described in the first aspect.

[0018] The first terminal of the power supply is connected to the input terminal of the main power circuit of the switching power supply, the output terminal of the main power circuit of the switching power supply is connected to the input terminal of the voltage feedback type switching voltage controller through the voltage sampling circuit, and the output terminal of the voltage feedback type switching voltage controller is connected to the control terminal of the main power circuit of the switching power supply.

[0019] The input terminal of the sampling module in the output voltage accuracy improvement device is connected to the output terminal of the main power circuit of the switching power supply. The emitter of the pull-down transistor in the output voltage accuracy improvement device is connected to the second terminal of the power supply. The second terminal of the pull-down resistor in the output voltage accuracy improvement device is connected to the input terminal of the voltage feedback type switching voltage controller.

[0020] Optionally, the voltage sampling circuit includes a second resistor voltage divider sampling circuit, the first end of which is connected to the output terminal of the main power circuit of the switching power supply, the second end of which is connected to the input terminal of the voltage feedback type switching voltage controller, and the third end of which is connected to the second terminal of the power supply.

[0021] Optionally, the second resistor voltage divider sampling circuit includes a first voltage divider resistor and a second voltage divider resistor. The first end of the first voltage divider resistor serves as the first end of the second resistor voltage divider sampling circuit and is connected to the output end of the main power circuit of the switching power supply. The second end of the first voltage divider resistor and the first end of the second voltage divider resistor form a second connection point. The second connection point serves as the second end of the second resistor voltage divider sampling circuit and is connected to the input end of the voltage feedback type switching voltage controller. The second end of the second voltage divider resistor serves as the third end of the second resistor voltage divider sampling circuit and is connected to the second end of the power supply.

[0022] Optionally, the resistance values ​​of the first voltage divider resistor and the second voltage divider resistor are determined based on the first target voltage of the main power circuit of the switching power supply. The first target voltage is the maximum possible output voltage of the main power circuit of the switching power supply caused by the resistance tolerance when the output voltage accuracy improvement device is not enabled. The first target voltage is lower than the design output voltage.

[0023] And / or, the value of the pull-down resistor is determined based on the second target voltage, the value of the first voltage divider resistor, and the value of the second voltage divider resistor, wherein the second target voltage is higher than the designed output voltage.

[0024] Thirdly, the present invention provides a control method for an output voltage accuracy improvement device, applied to controlling the output voltage accuracy improvement device as described in the first aspect, comprising:

[0025] The output voltage of the main power circuit of the switching power supply is collected by the sampling module and input to the error detection module.

[0026] The error detection module determines the difference between the first reference voltage and the output voltage.

[0027] The difference is input to the proportional-integral module, and the control quantity is determined by the proportional-integral module.

[0028] The control quantity is input to the pulse width modulation wave generation module, and the pulse width modulation wave generation module generates a PWM wave.

[0029] The base current of the pull-down transistor is controlled by the PWM wave to control the current flowing through the pull-down resistor, thereby adjusting the output voltage of the main power circuit of the switching power supply connected to the pull-down resistor and the pull-down transistor.

[0030] The beneficial effects of the output voltage accuracy improvement device and control method of the present invention, as well as the switching power supply, are as follows:

[0031] The sampling module acquires the output voltage of the main power circuit of the switching power supply in real time. Based on the difference between the output voltage and the first reference voltage determined by the error detection module, the proportional-integral module processes the difference to generate a corresponding control quantity. The pulse width modulation wave generation module generates a PWM signal with a corresponding duty cycle based on the control quantity, which is used to drive the base current of the pull-down transistor, thereby regulating the current flowing through the pull-down resistor.

[0032] Since the output voltage of a switching power supply is determined by both the voltage sampling circuit and the parallel-connected pull-down resistor, the output voltage can be fine-tuned by adjusting the current of the pull-down resistor. The pull-down resistor current is controlled by the first reference voltage. Therefore, without modifying the original main power control loop of the switching power supply (i.e., without altering the second reference voltage and its feedback logic within the voltage feedback type switching voltage controller), the output voltage accuracy can be improved simply by configuring the accuracy of the first reference voltage.

[0033] Furthermore, the first reference voltage is preset as a high-precision reference that ensures the output voltage meets a preset accuracy requirement (e.g., ±0.1%). When the external output voltage accuracy enhancement device is activated, the system output voltage is corrected to the target accuracy range without the need to redesign or customize the controller, significantly reducing development workload and cost.

[0034] Furthermore, separating the output voltage accuracy control function from the main power control loop as an external module, instead of integrating it into the main power control loop, not only improves the configurability and adaptability of the output voltage accuracy control, but also facilitates flexible adjustment, upgrading, or disabling of this function according to actual application needs, thereby enhancing the product's versatility and maintenance convenience. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a switching power supply according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the structure of a switching power supply according to another embodiment of the present invention;

[0037] Figure 3 This is a flowchart illustrating the control method of the output voltage accuracy improvement device according to another embodiment of the present invention. Detailed Implementation

[0038] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0039] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0040] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0041] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0042] The names of the messages or information exchanged between the multiple devices in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0043] In related technologies, to improve the output voltage accuracy of switching power supplies, it is usually necessary to redesign or customize a dedicated controller. However, the internal reference voltage of the switching power supply controller is tightly coupled with its main power control logic; if the reference voltage is modified, the relevant control logic and parameter configuration must be adjusted accordingly, which leads to a longer development cycle, increased engineering implementation complexity, and thus significantly increased development workload and cost.

[0044] To address the problems existing in the aforementioned related technologies, this embodiment provides an output voltage accuracy improvement device and its control method, as well as a switching power supply.

[0045] like Figure 1 and 2 As shown, an embodiment of the present invention provides an output voltage accuracy improvement device, comprising:

[0046] A sampling module, the input terminal of which is used to obtain the output voltage of the main power circuit of the switching power supply, the input terminal of which is connected to the first terminal of the power supply;

[0047] An error detection module is provided, the input of which is connected to the output of the sampling module. The error detection module is used to determine the difference between a first reference voltage and the output voltage. The accuracy of the first reference voltage is configured to ensure that the output voltage meets a preset accuracy requirement.

[0048] A proportional-integral module, wherein the input of the proportional-integral module is connected to the output of the error detection module;

[0049] A pulse width modulation wave generation module, wherein the input terminal of the pulse width modulation wave generation module is connected to the output terminal of the proportional-integral module;

[0050] The system includes a pull-down resistor and a pull-down transistor. The base of the pull-down transistor is connected to the output terminal of the pulse width modulation wave generation module. The collector of the pull-down transistor is connected to the first terminal of the pull-down resistor. The emitter of the pull-down transistor is configured to be connected to the second terminal of the power supply. The second terminal of the pull-down resistor is configured to be connected to the input terminal of a voltage feedback type switching voltage controller. The input terminal of the voltage feedback type switching voltage controller is also connected to the output terminal of the main power circuit of the switching power supply through a voltage sampling circuit. The output terminal of the voltage feedback type switching voltage controller is connected to the control terminal of the main power circuit of the switching power supply.

[0051] Specifically, the sampling module is used to collect the output voltage of the main power circuit of the switching power supply, that is, the output voltage of the switching power supply. It can be a resistor voltage divider sampling circuit or a voltage sensor, etc.

[0052] The error detection module is used to determine the difference between the first reference voltage and the output voltage. The first reference voltage is used to adjust the output voltage of the main power circuit of the switching power supply to stabilize it at the designed output voltage, which is the voltage expected to be output by the main power circuit of the switching power supply. Assuming other system errors (such as voltage sampling accuracy, temperature drift, and noise) are taken into account, the accuracy of the first reference voltage should meet the preset accuracy requirement (e.g., ±0.1%), meaning that the output voltage error it causes does not exceed the preset output accuracy requirement.

[0053] The pull-down resistor and pull-down transistor form the regulation branch. The output voltage of the main power circuit of the switching power supply is determined by the voltage across the voltage sampling circuit and the voltage across the regulation branch. When the control voltage of the pull-down transistor changes, the current flowing through the pull-down resistor changes, thus regulating the output voltage of the main power circuit of the switching power supply.

[0054] Among them, the main power circuit of the switching power supply refers to the core high-power part of the switching power supply that directly undertakes the function of power conversion and transmission. It is responsible for efficiently and stably converting the input power (such as AC mains power or DC bus power) into the required output voltage / current, such as DC / DC circuits or AC / DC circuits such as BUCk circuit.

[0055] A voltage feedback switching voltage controller, as a key component of the main power control loop, is a switching power supply controller that uses the output voltage as a feedback signal to regulate switching actions through closed-loop control, thereby stabilizing the output voltage. A voltage feedback switching voltage controller may include an error amplifier, a comparator, and a pulse width modulation waveform generator connected in sequence.

[0056] In this embodiment, the output voltage of the main power circuit of the switching power supply is obtained in real time by the sampling module, and the difference between the output voltage and the first reference voltage determined by the error detection module is processed by the proportional-integral module to generate a corresponding control quantity. The pulse width modulation wave generation module generates a PWM signal with a corresponding duty cycle according to the control quantity, which is used to drive the base current of the pull-down transistor, thereby adjusting the current flowing through the pull-down resistor.

[0057] Since the output voltage of a switching power supply is determined by both the voltage sampling circuit and the parallel-connected pull-down resistor, the output voltage can be fine-tuned by adjusting the current of the pull-down resistor. The pull-down resistor current is controlled by the first reference voltage. Therefore, without modifying the original main power control loop of the switching power supply (i.e., without altering the second reference voltage and its feedback logic within the voltage feedback type switching voltage controller), the output voltage accuracy can be improved simply by configuring the accuracy of the first reference voltage.

[0058] Furthermore, the first reference voltage is preset as a high-precision reference that ensures the output voltage meets a preset accuracy requirement (e.g., ±0.1%). When the external output voltage accuracy enhancement device is activated, the system output voltage is corrected to the target accuracy range without the need to redesign or customize the controller, significantly reducing development workload and cost.

[0059] Furthermore, separating the output voltage accuracy control function from the main power control loop as an external module, instead of integrating it into the main power control loop, not only improves the configurability and adaptability of the output voltage accuracy control, but also facilitates flexible adjustment, upgrading, or disabling of this function according to actual application needs, thereby enhancing the product's versatility and maintenance convenience.

[0060] Optionally, the sampling accuracy of the sampling module is configured to ensure that the output voltage meets a preset accuracy requirement.

[0061] Specifically, under the premise that the influence of other system error sources has been limited or kept unchanged, by selecting a high-precision reference voltage source and improving the voltage sampling accuracy of the sampling module, the output voltage of the main power circuit of the switching power supply can meet the preset accuracy requirements.

[0062] Optionally, the sampling module includes a first resistor voltage divider sampling circuit, the first end of which serves as the input terminal of the sampling module and is connected to the output terminal of the main power circuit of the switching power supply, the second end of which serves as the output terminal of the sampling module and is connected to the input terminal of the error detection module, and the third end of which is connected to the second terminal of the power supply.

[0063] Optionally, such as Figure 2As shown, the first resistor voltage divider sampling circuit includes an upper voltage divider resistor R11 and a lower voltage divider resistor R21. The first end of the upper voltage divider resistor R11 serves as the first end of the first resistor voltage divider sampling circuit and is connected to the output end of the main power circuit of the switching power supply. The second end of the upper voltage divider resistor R11 is connected to the first end of the lower voltage divider resistor R21 to form a first connection point. The first connection point serves as the second end of the first resistor voltage divider sampling circuit and is connected to the input end of the error detection module. The second end of the lower voltage divider resistor R21 serves as the third end of the first resistor voltage divider sampling circuit and is connected to the second end of the power supply.

[0064] Optionally, the voltage sampling circuit includes a second resistor voltage divider sampling circuit, the first end of which is connected to the output terminal of the main power circuit of the switching power supply, the second end of which is connected to the input terminal of the voltage feedback type switching voltage controller, and the third end of which is connected to the second terminal of the power supply.

[0065] Optionally, such as Figure 1 As shown, the second resistor voltage divider sampling circuit includes a first voltage divider resistor R1 and a second voltage divider resistor R2. The first end of the first voltage divider resistor R1 serves as the first end of the second resistor voltage divider sampling circuit and is connected to the output end of the main power circuit of the switching power supply. The second end of the first voltage divider resistor R1 and the first end of the second voltage divider resistor R2 form a second connection point, which serves as the second end of the second resistor voltage divider sampling circuit and is connected to the input end of the voltage feedback type switching voltage controller. The second end of the second voltage divider resistor R2 serves as the third end of the second resistor voltage divider sampling circuit and is connected to the second end of the power supply.

[0066] The principle of the output voltage accuracy improvement device in this embodiment for improving output voltage accuracy will be explained in detail below:

[0067] When the output voltage accuracy enhancement device is not activated, the formula for calculating the output voltage is as shown in the first formula:

[0068] ,

[0069] in, Vout This indicates the output voltage of the main power circuit of the switching power supply. Vref This represents the second reference voltage inside the voltage feedback switching power supply controller. When the feedback control reaches a steady state, the voltage at the input of the voltage feedback switching power supply controller is equal to... Vref , R1 This represents the first voltage divider resistor in the second resistor voltage divider sampling circuit. R2This indicates the second voltage divider resistor in the second resistor voltage divider sampling circuit.

[0070] As can be seen from the first formula, when the output voltage accuracy enhancement device is not activated, the accuracy of the output voltage of the main power circuit of the switching power supply is affected by the accuracy of the first voltage divider resistor, the second voltage divider resistor, and the second reference voltage inside the voltage feedback switching power supply controller. However, the accuracy of the second reference voltage is fixed during device manufacturing and is difficult to modify.

[0071] After activating the output voltage accuracy enhancement device, the calculation formula for the output voltage is as shown in the second formula:

[0072] Vout=Vref*(1+R1 / R2)+Ice*R1 ,

[0073] in, Ice This represents the current flowing through the pull-down resistor R3.

[0074] As can be seen from the second formula, after the output voltage accuracy improvement device is activated, the accuracy of the output voltage of the main power circuit of the switching power supply is affected not only by the accuracy of the first voltage divider resistor, the second voltage divider resistor, and the second reference voltage inside the voltage feedback switching power supply controller, but also by the current flowing through the pull-down resistor R3. Specifically, by adjusting the current... Ice It can also correct the output voltage and current. Ice Affected by the sampling accuracy of the sampling module and the accuracy of the first reference voltage of the error detection module in the output voltage accuracy enhancement device, since the sampling accuracy of the voltage sampling circuit and the accuracy of the first reference voltage are configured to meet the preset accuracy requirements of the output voltage, the output voltage accuracy can be improved by externally connecting and enabling the output voltage accuracy enhancement device without changing the main power control loop (i.e. without modifying the second reference voltage in the voltage feedback type switching voltage controller, and without replacing the first voltage divider resistor R1 and the second voltage divider resistor R2).

[0075] When the sampling module in the output voltage accuracy improvement device adopts, such as Figure 2 When using the first resistor-divided voltage sampling circuit shown, the formula for calculating the output voltage can also be shown in the third formula:

[0076] ,

[0077] in, Vref2 This represents the first reference voltage of the error detection module in the output voltage accuracy improvement device. R11 This refers to the upper voltage divider resistor in the first resistor voltage divider sampling circuit. R21 This represents the lower voltage divider resistor in the first voltage divider sampling circuit, and the upper voltage divider resistor when the feedback control reaches a stable state. R11 With the lower voltage divider resistor R21 The voltage at the connection point is equal to Vref2 .

[0078] According to the third formula, it can be seen more directly that after the output voltage accuracy improvement device is activated, the accuracy of the output voltage of the main power circuit of the switching power supply is mainly affected by the first reference voltage. Vref2 Upper voltage divider resistor R11 and lower voltage divider resistor R21 The influence of the first reference voltage Vref2 Upper voltage divider resistor R11 and lower voltage divider resistor R21 Designed for high precision to ensure that the output voltage meets the preset accuracy requirements, the output voltage accuracy of the switching power supply can be improved by adding and enabling an external output voltage accuracy enhancement device. This eliminates the need to redevelop a voltage feedback switching voltage controller and reselect the first and second voltage divider resistors, effectively reducing development workload and costs.

[0079] Optionally, the accuracy of the upper voltage divider resistor and the lower voltage divider resistor is configured to ensure that the output voltage meets a preset accuracy requirement. For example, when upper and lower voltage divider resistors with corresponding accuracy are used, the accuracy of the output voltage can meet the preset accuracy requirement (e.g., ±0.1%).

[0080] Specifically, as can be seen from the third formula, the voltage acquisition accuracy can be improved by selecting higher precision upper and lower voltage divider resistors, thereby improving the output voltage accuracy of the main power circuit of the switching power supply.

[0081] like Figure 1 As shown, another embodiment of the present invention provides a switching power supply, including a power supply, a main power circuit of the switching power supply, a voltage feedback type switching voltage controller, a voltage sampling circuit, and an output voltage accuracy improvement device as described above;

[0082] The first terminal of the power supply is connected to the input terminal of the main power circuit of the switching power supply, the output terminal of the main power circuit of the switching power supply is connected to the input terminal of the voltage feedback type switching voltage controller through the voltage sampling circuit, and the output terminal of the voltage feedback type switching voltage controller is connected to the control terminal of the main power circuit of the switching power supply.

[0083] The input terminal of the sampling module in the output voltage accuracy improvement device is connected to the output terminal of the main power circuit of the switching power supply. The emitter of the pull-down transistor in the output voltage accuracy improvement device is connected to the second terminal of the power supply. The second terminal of the pull-down resistor in the output voltage accuracy improvement device is connected to the input terminal of the voltage feedback type switching voltage controller.

[0084] Specifically, the power supply can be a DC power supply, with the first terminal being positive and the second terminal being negative, which can be grounded. The sampling module acquires the output voltage of the main power circuit of the switching power supply. The error detection module subtracts the acquired output voltage from the first reference voltage to obtain the voltage difference E1. The proportional-integral module processes the voltage difference E1 to obtain the control quantity E2. It is determined whether the voltage difference E1 is equal to 0. If it is, it indicates that the output voltage has reached the designed output voltage, and the control process ends. If not, the pulse width modulation (PWM) wave generation module generates a PWM wave with a corresponding duty cycle based on the control quantity E2. After filtering, the PWM wave generates a voltage, which adjusts the base current of the pull-down transistor to adjust the output voltage of the target power supply circuit.

[0085] Specifically, when the voltage difference E1 is greater than 0, the duty cycle of the PWM wave is increased to increase the output voltage; when the voltage difference E1 is less than 0, the duty cycle of the PWM wave is decreased to decrease the output voltage.

[0086] In this embodiment, since the output voltage of the switching power supply is determined by the voltage sampling circuit and the parallel-connected pull-down resistor, the output voltage can be finely adjusted by adjusting the current of the pull-down resistor. The current of the pull-down resistor is controlled by the first reference voltage. Therefore, without modifying the original main power control loop of the switching power supply (i.e., without changing the second reference voltage and its feedback logic within the voltage feedback type switching voltage controller), the accuracy of the output voltage can be improved simply by configuring the accuracy of the first reference voltage.

[0087] Furthermore, the first reference voltage is preset as a high-precision reference that ensures the output voltage meets a preset accuracy requirement (e.g., ±0.1%). When the external output voltage accuracy enhancement device is activated, the system output voltage is corrected to the target accuracy range without the need to redesign or customize the controller, significantly reducing development workload and cost.

[0088] Furthermore, separating the output voltage accuracy control function from the main power control loop as an external module, instead of integrating it into the main power control loop, not only improves the configurability and adaptability of the output voltage accuracy control, but also facilitates flexible adjustment, upgrading, or disabling of this function according to actual application needs, thereby enhancing the product's versatility and maintenance convenience.

[0089] Optionally, the resistance values ​​of the first voltage divider resistor and the second voltage divider resistor are determined based on the first target voltage of the main power circuit of the switching power supply. The first target voltage is the maximum possible output voltage of the main power circuit of the switching power supply caused by the resistance tolerance when the output voltage accuracy improvement device is not enabled. The first target voltage is lower than the design output voltage.

[0090] And / or, the value of the pull-down resistor is determined based on the second target voltage, the value of the first voltage divider resistor, and the value of the second voltage divider resistor, wherein the second target voltage is higher than the designed output voltage.

[0091] Specifically, firstly, without activating the output voltage accuracy enhancement device, a first target voltage is set. This first target voltage needs to be lower than the designed output voltage. Specifically, the difference between the designed output voltage and a first preset voltage threshold is defined as the first target voltage, which can be 0.5V. Multiple voltage divider resistor combinations are selected. Each combination includes a first voltage divider resistor with one resistance value and a second voltage divider resistor with one resistance value. Due to resistance tolerance, the output voltage of the main power circuit of the switching power supply corresponding to each voltage divider resistor combination corresponds to a voltage range. The voltage divider resistor combination whose maximum voltage within the voltage range equals the first target voltage is selected as the target resistor combination. The resistance values ​​in the target resistor combination are then determined as the resistance values ​​of the first and second voltage dividers.

[0092] The second target voltage needs to be higher than the design output voltage to ensure that the output voltage accuracy enhancement device can be activated to raise the output voltage above the design output voltage.

[0093] With the values ​​of the first and second voltage divider resistors determined, the output voltage accuracy enhancement device is activated, and pull-down resistors with different resistance values ​​are selected. Taking into account the tolerance of each resistor, the corresponding pull-down resistor value is determined until the second target voltage is within the voltage range corresponding to the output voltage of the main power circuit of the switching power supply.

[0094] In this optional embodiment, when the output voltage accuracy enhancement device is activated, the pull-down resistor and the second voltage divider resistor are connected in parallel, which will cause the output voltage of the main power circuit of the switching power supply to rise instantaneously. In order to avoid the output voltage from deviating from the design output voltage due to the large overshoot caused by this transient process, the output voltage when the output voltage accuracy enhancement device is not activated is limited to below the design output voltage, so that after the output voltage accuracy enhancement device is activated, the output voltage will tend to adjust towards the design output voltage, effectively suppressing transient deviation.

[0095] like Figure 3 As shown, another embodiment of the present invention provides a control method for an output voltage accuracy improvement device, applied to control the output voltage accuracy improvement device as described above, including:

[0096] S100 collects the output voltage of the main power circuit of the switching power supply through the sampling module and inputs it to the error detection module.

[0097] Specifically, the sampling module is used to collect the output voltage of the main power circuit of the switching power supply, that is, the output voltage of the switching power supply. It can be a resistor voltage divider sampling circuit or a voltage sensor, etc.

[0098] S200, the difference between the first reference voltage and the output voltage is determined by the error detection module.

[0099] Specifically, the error detection module is used to determine the difference between the first reference voltage and the output voltage, i.e., the error signal. A subtractor such as a differential amplifier can be used.

[0100] S300, the difference is input to the proportional-integral module, and the control quantity is determined by the proportional-integral module.

[0101] Specifically, the proportional-integral module (PI module) processes the error signal and outputs a continuous control quantity.

[0102] S400, the control quantity is input to the pulse width modulation wave generation module, and the pulse width modulation wave generation module generates a PWM wave.

[0103] Specifically, the pulse width modulation wave generation module generates a PWM wave with a corresponding duty cycle based on the control quantity.

[0104] S500 controls the base current of the pull-down transistor according to the PWM wave, thereby controlling the current flowing through the pull-down resistor and adjusting the output voltage of the main power circuit of the switching power supply connected to the pull-down resistor and the pull-down transistor.

[0105] Specifically, the PWM wave is filtered to generate a voltage, which can be achieved using an RC filter, etc. More specifically, the output of the pulse width modulation wave generator is connected to the base of a pull-down transistor via an RC filter. The generated voltage controls the base current of the pull-down transistor, thereby controlling the current flowing through the pull-down resistor, and consequently controlling the voltage of the voltage sampling circuit connected in parallel to the main power circuit of the switching power supply, thus correcting the output voltage of the main power circuit of the switching power supply.

[0106] In this embodiment, since the output voltage of the switching power supply is determined by the voltage sampling circuit and the parallel-connected pull-down resistor, the output voltage can be finely adjusted by adjusting the current of the pull-down resistor. The current of the pull-down resistor is controlled by the first reference voltage. Therefore, without modifying the original main power control loop of the switching power supply (i.e., without changing the second reference voltage and its feedback logic within the voltage feedback type switching voltage controller), the accuracy of the output voltage can be improved simply by configuring the accuracy of the first reference voltage.

[0107] Furthermore, the first reference voltage is preset as a high-precision reference that ensures the output voltage meets a preset accuracy requirement (e.g., ±0.1%). When the external output voltage accuracy enhancement device is activated, the system output voltage is corrected to the target accuracy range without the need to redesign or customize the controller, significantly reducing development workload and cost.

[0108] Furthermore, separating the output voltage accuracy control function from the main power control loop as an external module, instead of integrating it into the main power control loop, not only improves the configurability and adaptability of the output voltage accuracy control, but also facilitates flexible adjustment, upgrading, or disabling of this function according to actual application needs, thereby enhancing the product's versatility and maintenance convenience.

[0109] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc. In this application, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs. Furthermore, the functional units in the various embodiments of the present invention 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. The integrated units can be implemented in hardware or as software functional units.

[0110] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A device for improving output voltage accuracy, characterized in that, include: A sampling module, the input terminal of which is used to obtain the output voltage of the main power circuit of the switching power supply, the input terminal of which is connected to the first terminal of the power supply; An error detection module is provided, the input of which is connected to the output of the sampling module. The error detection module is used to determine the difference between a first reference voltage and the output voltage. The accuracy of the first reference voltage is configured to ensure that the output voltage meets a preset accuracy requirement. A proportional-integral module, wherein the input of the proportional-integral module is connected to the output of the error detection module; A pulse width modulation wave generation module, wherein the input terminal of the pulse width modulation wave generation module is connected to the output terminal of the proportional-integral module; The system includes a pull-down resistor and a pull-down transistor. The base of the pull-down transistor is connected to the output of the pulse width modulation (PWM) wave generation module. The collector of the pull-down transistor is connected to the first end of the pull-down resistor. The emitter of the pull-down transistor is configured to be connected to the second end of the power supply. The second end of the pull-down resistor is configured to be connected to the input of a voltage feedback type switching voltage controller. The input of the voltage feedback type switching voltage controller is also connected to the output of the main power circuit of the switching power supply via a voltage sampling circuit. The output of the voltage feedback type switching voltage controller is connected to the control terminal of the main power circuit of the switching power supply. The voltage sampling circuit includes a second resistor voltage divider sampling circuit. The first end of the second resistor voltage divider sampling circuit is connected to the output of the main power circuit of the switching power supply. The second end of the second resistor voltage divider sampling circuit is connected to the input of the voltage feedback type switching voltage controller. The third end of the second resistor voltage divider sampling circuit is connected to the second end of the power supply.

2. The output voltage accuracy improvement device according to claim 1, characterized in that, The sampling accuracy of the sampling module is configured to ensure that the output voltage meets a preset accuracy requirement.

3. The output voltage accuracy improvement device according to claim 1, characterized in that, The sampling module includes a first resistor voltage divider sampling circuit. The first end of the first resistor voltage divider sampling circuit is used as the input end of the sampling module and is connected to the output end of the main power circuit of the switching power supply. The second end of the first resistor voltage divider sampling circuit is used as the output end of the sampling module and is connected to the input end of the error detection module. The third end of the first resistor voltage divider sampling circuit is connected to the second end of the power supply.

4. The output voltage accuracy improvement device according to claim 3, characterized in that, The first resistor voltage divider sampling circuit includes an upper voltage divider resistor and a lower voltage divider resistor. The first end of the upper voltage divider resistor serves as the first end of the first resistor voltage divider sampling circuit and is connected to the output end of the main power circuit of the switching power supply. The second end of the upper voltage divider resistor is connected to the first end of the lower voltage divider resistor to form a first connection point. The first connection point serves as the second end of the first resistor voltage divider sampling circuit and is connected to the input end of the error detection module. The second end of the lower voltage divider resistor serves as the third end of the first resistor voltage divider sampling circuit and is connected to the second end of the power supply.

5. The output voltage accuracy improvement device according to claim 4, characterized in that, The accuracy of the upper voltage divider resistor and the lower voltage divider resistor is configured to ensure that the output voltage meets a preset accuracy requirement.

6. A switching power supply, characterized in that, Includes a power supply, a main power circuit for a switching power supply, a voltage feedback type switching voltage controller, a voltage sampling circuit, and an output voltage accuracy improvement device as described in any one of claims 1 to 5; The first terminal of the power supply is connected to the input terminal of the main power circuit of the switching power supply, the output terminal of the main power circuit of the switching power supply is connected to the input terminal of the voltage feedback type switching voltage controller through the voltage sampling circuit, and the output terminal of the voltage feedback type switching voltage controller is connected to the control terminal of the main power circuit of the switching power supply. The input terminal of the sampling module in the output voltage accuracy improvement device is connected to the output terminal of the main power circuit of the switching power supply. The emitter of the pull-down transistor in the output voltage accuracy improvement device is connected to the second terminal of the power supply. The second terminal of the pull-down resistor in the output voltage accuracy improvement device is connected to the input terminal of the voltage feedback type switching voltage controller.

7. The switching power supply according to claim 6, characterized in that, The second resistor voltage divider sampling circuit includes a first voltage divider resistor and a second voltage divider resistor. The first end of the first voltage divider resistor serves as the first end of the second resistor voltage divider sampling circuit and is connected to the output end of the main power circuit of the switching power supply. The second end of the first voltage divider resistor and the first end of the second voltage divider resistor form a second connection point. The second connection point serves as the second end of the second resistor voltage divider sampling circuit and is connected to the input end of the voltage feedback type switching voltage controller. The second end of the second voltage divider resistor serves as the third end of the second resistor voltage divider sampling circuit and is connected to the second end of the power supply.

8. The switching power supply according to claim 7, characterized in that, The resistance values ​​of the first voltage divider resistor and the second voltage divider resistor are determined based on the first target voltage of the main power circuit of the switching power supply. The first target voltage is the maximum possible output voltage of the main power circuit of the switching power supply caused by the resistance tolerance when the output voltage accuracy improvement device is not enabled. The first target voltage is lower than the design output voltage. And / or, the value of the pull-down resistor is determined based on the second target voltage, the value of the first voltage divider resistor, and the value of the second voltage divider resistor, wherein the second target voltage is higher than the designed output voltage.

9. A control method for an output voltage accuracy improvement device, characterized in that, An application for controlling the output voltage accuracy improvement device as described in any one of claims 1 to 5, comprising: The output voltage of the main power circuit of the switching power supply is collected by the sampling module and input to the error detection module. The error detection module determines the difference between the first reference voltage and the output voltage. The difference is input to the proportional-integral module, and the control quantity is determined by the proportional-integral module. The control quantity is input to the pulse width modulation wave generation module, and the pulse width modulation wave generation module generates a PWM wave. The base current of the pull-down transistor is controlled by the PWM wave to control the current flowing through the pull-down resistor, thereby adjusting the output voltage of the main power circuit of the switching power supply connected to the pull-down resistor and the pull-down transistor.

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