Improved linear gain digital control method

Abstract

The invention belongs to the technical field of power supplies, and discloses an improved linear gain digital control method, which comprises the following steps: S1, determining a target value of a circuit output voltage, and detecting an actual value of the circuit output voltage; s2, subtracting the actual value of the output voltage from the target value of the output voltage to obtain a voltage error value Error; s3, a linear gain value KD is determined according to the voltage error value Error, and when Error is smaller than a, KD is A; when Error is greater than b, KD is B; when a < = Error < = b, the value of KD is A-B; wherein a is smaller than b, and A is smaller than B; s4, loop control is carried out on the circuit, loop control comprises PI control, when PI control operation is carried out, U (t) = Kp * KD * Error (t) + Ki * KD * summa Error (t), and Kp and Ki are coefficients of PI control; and S5, adjusting the operation of the circuit according to a loop operation result. The method has the beneficial effects that the loop output is changed along with the gain, and the loop response speed can be greatly improved without changing the existing control framework.

Description

Technical Field

[0001] The invention relates to the technical field of power supply, and in particular to an improved linear gain digital control method. Background Art

[0002] With the continuous development of the power electronics industry, the requirements for the power supply industry are getting higher and higher. In order to better meet the dynamic specifications of GPU servers for EDPP and the interactive dynamic capabilities of large loads, it is particularly important to provide an efficient, simple and low-cost loop control solution. In order for the switching power supply to meet the performance indicators of EDPP and interactive dynamics, it is necessary to improve the dynamic response of the output voltage. The response of the output voltage is affected by the BULK voltage at the PFC end. Therefore, the most direct optimization direction is to adjust the control effect of the BULK voltage. The existing BULK voltage control scheme has the following disadvantages: 1. Using the output as feedback, the response is delayed; 2. There are many loop parameters, and the control is complex and has steps; 3. The loop control stabilization time is relatively long.

[0003] Therefore, it is necessary to provide an improved linear gain digital control method that can make the BULK of the voltage loop control

[0004] The voltage meets the control requirements, greatly improving the loop response. Summary of the invention

[0005] The invention discloses an improved linear gain digital control method, which can effectively solve the technical problems involved in the background technology.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] An improved linear gain digital control method comprises the following steps:

[0008] S1. Determine the target value of the circuit output voltage and detect the actual value of the circuit output voltage;

[0009] S2. The actual value of the output voltage is subtracted from the target value of the output voltage to obtain the voltage error value Error;

[0010] S3. Determine the linear gain value K according to the voltage error value Error D , where |Error|〈a, K D When A; |Error|〉b, K D is B; when a≤|Error|≤b, K D The value is AB; where a〈b, A〈B;

[0011] S4. The circuit performs loop control, which includes PI control. During PI control operation, U(t) = Kp×K D×Error(t)+Ki×K D ×∫Error(t), where Kp and Ki are the coefficients of PI control;

[0012] S5. Adjust the operation of the circuit according to the loop operation result.

[0013] Specifically, the present invention is applicable to first-order feedback control systems of all digital schemes, and provides an improved linear gain digital control method. The linear gain is used to optimize the control effect of the original system, which can greatly improve the dynamic response speed of the control system. It relates to the field of AC / DC power conversion, and in particular to the BULK voltage control effect of PFC under harsh working conditions. By designing a set of linear gain control logic for the voltage loop control on the PFC side, the loop control system can linearly follow the linear gain change to achieve the purpose of adaptive control. Within the gain range, the control loop output can be quickly and stably controlled, and the loop response speed under extreme working conditions can be greatly optimized to improve the control system performance. However, this method is not limited to use in PFC, and can be applied to many control circuits. The linear gain control logic is designed through the feedback signal of the first-order feedback control system to obtain a higher system control effect.

[0014] As a preferred improvement of the present invention: in step S3, when a≤|Error|≤b, K D The value is AB, and K D It has a linear relationship with |Error|.

[0015] As a preferred improvement of the present invention: when a=10V, b=25V, A=1, B=16, a≤|Error|≤b, K D＝ |Error|-9.

[0016] As a preferred improvement of the present invention: the Kp is 0.25 and the Ki is 0.0005.

[0017] As a preferred improvement of the present invention: the circuit includes but is not limited to a PFC circuit.

[0018] As a preferred improvement of the present invention: the output voltage is a BULK voltage.

[0019] As a preferred improvement of the present invention: the step S5 specifically includes adjusting the conduction rate of the MOS tube in the circuit according to the loop operation result.

[0020] As a preferred improvement of the present invention: the loop control includes PI control and current loop control, and the current loop control operation is performed after the PI control operation.

[0021] The beneficial effects of the present invention are as follows:

[0022] Introducing linear gain K into the existing control logic D , K D The gain curve is calculated based on the error between the target BULK voltage and the actual BULK voltage. D The introduction of loop control can quickly adjust the voltage loop output stable BULK voltage, so that the loop output follows the gain change, which can greatly improve the loop response speed without changing the existing control framework. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0024] Figure 1 A control logic diagram of an improved linear gain digital control method of the present invention;

[0025] Figure 2 This is a schematic diagram of the loop gain curve. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0031] Definition of terms: PFC: Power Factor Correction; BULK: PFC Output Voltage; EDPP: Electrical Date Peak Processing; Error: Error OfBULK Voltage; PI: ProportionIntegration; Kp: Proportion; Ki: Integral.

[0032] After in-depth analysis, the key performance indicator for optimizing EDPP and interactive dynamics is to improve the control ability of the BULK voltage on the PFC side (such as shallow BULK voltage drop, small overshoot, fast climb, stable and no jitter). According to the control logic of PFC, the BULK voltage is controlled by the voltage loop, and the voltage loop as an outer loop has a low control frequency, and the input signal of the voltage loop can only jump segment parameters according to the output BULK voltage, resulting in slow overall response and poor adjustment ability of the loop. Therefore, the existing voltage loop control method is optimized, and a linear gain K is introduced on the existing control logic. D , K D The gain curve is calculated based on the error between the target BULK voltage and the actual BULK voltage. D The introduction of loop control can quickly adjust the voltage loop to output a stable BULK voltage.

[0033] The basic logic of the voltage loop is as follows: PI control formula: U(t) = Kp*Error(t) + Ki*∫Error(t), the integral range is generally 0-4096, Kp and Ki are PI control coefficients, and the values ​​can be adjusted by yourself. According to the PI parameter control of the voltage loop, the upper and lower limits of the BULK voltage are affected by Kp; the climbing rate of the BULK voltage is affected by Ki, so a set of gain control logic is designed according to the voltage difference between the BULK voltage and the target voltage, so that Kp and Ki systematically follow this linear logic change, such as Figure 2 , in order to achieve the purpose of adaptive control, so that the loop output follows the gain change, the loop response can be greatly improved without changing the existing control framework.

[0034] See also Figure 1 As shown, the present invention provides an improved linear gain digital control method, comprising the following steps: S1, determining the target value of the circuit output voltage, and detecting the actual value of the circuit output voltage; S2, subtracting the actual value of the output voltage from the target value of the output voltage to obtain a voltage error value Error; S3, determining a linear gain value K according to the voltage error value Error D , where |Error|〈a, K D When A; |Error|〉b, K D is B; when a≤|Error|≤b, K D The value is AB; where a < b, A < B; S4, the circuit performs loop control, the loop control includes PI control, when PI control operation, U(t) = Kp × K D ×Error(t)+Ki×K D ×∫Error(t), where Kp and Ki are the coefficients of PI control; S5, adjust the operation of the circuit according to the loop operation result.

[0035] As an implementation manner, in step S3, when a≤|Error|≤b, K D The value is AB, and K D It has a linear function relationship with |Error|. According to the design logic, the linear gain formula Y=K×X+T is calculated, and the gain is limited to 1-16 times (not more than 32 times to avoid overflow). If the voltage loop gain K is to be D Following the input voltage error Error, the gain range and the input voltage error range are introduced into the linear formula to obtain: 1 = K × 10 + T; 16 = K × 25 + T; K = 1; T = -9; finally, the PI control formula is K D =1×Error-9; K DThe range of error and error can be designed according to the actual situation. Therefore, when a=10V, b=25V, A=1, B=16, a≤|Error|≤b, K D＝ |Error|-9. The Kp is 0.25, and the Ki is 0.0005. The circuit includes but is not limited to a PFC circuit, and the output voltage is a BULK voltage. The step S5 specifically comprises adjusting the conduction rate of the MOS tube in the circuit according to the loop operation result, and the loop control includes PI control and current loop control, and the current loop control operation is performed after the PI control operation. It should be further explained that the use of other components to achieve the above-mentioned effects should all fall within the inventive concept of the present invention and should fall within the protection scope of the present invention.

[0036] Embodiment 1

[0037] |Error|<10V, gain K D Fixed to 1 to ensure that there is no oscillation due to gain changes within the ripple range;

[0038] |Error|≥10V and Error≤25V, gain KD is 1-16. The greater the error, the greater the gain and the stronger the loop regulation capability.

[0039] |Error|>25V, gain K D The value is 16. In order to avoid overshoot caused by excessive gain, this error is used as the maximum value of the gain limit.

[0040] The loop gain K D Introduce the above control formula: U(t)=Kp*K D *Error(t)+Ki*K D *∫Error(t).

[0041] By digitizing the above logic and obtaining the gain curve formula, the BULK voltage controlled by the voltage loop can meet the control requirements, and the loop response can be greatly improved without changing the existing control framework.

[0042] A dynamic test comparison experiment was performed on a 2000W switching power supply. The results are shown in the following table. The results show that this countermeasure can significantly improve the dynamic performance of the BULK voltage.

[0043]

[0044] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the embodiments. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. An improved linear gain digital control method, characterized in that: The following steps are involved: S1. Determine the target value of the circuit output voltage and detect the actual value of the circuit output voltage; S2. The actual value of the output voltage is subtracted from the target value of the output voltage to obtain the voltage error value Error; S3. Determine the linear gain value K according to the voltage error value Error D , where |Error|〈a, K D When A; |Error|〉b, K D is B; when a≤|Error|≤b, K D The value is AB; where a〈b, A〈B; S4. The circuit performs loop control, which includes PI control. During PI control operation, U(t) = Kp×K D ×Error(t)+Ki×K D ×∫Error(t), where Kp and Ki are the coefficients of PI control; S5. Adjust the operation of the circuit according to the loop operation result.

2. The improved linear gain digital control method according to claim 1, characterized in that: In step S3, when a≤|Error|≤b, K D The value is AB, and K D It has a linear relationship with |Error|.

3. The improved linear gain digital control method according to claim 2, characterized in that: When a=10V,b=25V,A=1,B=16,a≤|Error|≤b,K D＝ |Error|-9.

4. The improved linear gain digital control method according to claim 1, characterized in that: The Kp is set to 0.25, and the Ki is set to 0.0005.

5. The improved linear gain digital control method according to claim 1, characterized in that: The circuit includes but is not limited to a PFC circuit.

6. The improved linear gain digital control method according to claim 1, characterized in that: The output voltage is a BULK voltage.

7. The improved linear gain digital control method according to claim 1, characterized in that: The step S5 specifically includes adjusting the conduction rate of the MOS tube in the circuit according to the loop operation result.

8. The improved linear gain digital control method according to claim 1, characterized in that: The loop control includes PI control and current loop control, and the current loop control operation is performed after the PI control operation.

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