Method for improving dynamic performance of DCDC

Abstract

The invention belongs to the technical field of switching power supplies, and discloses a method for improving the dynamic performance of DCDC, a first-order RC differentiating circuit is added at an output voltage sampling end, a voltage jump signal is preferentially captured and fed back to a controller, the controller adjusts the proportionality coefficient of a loop compensator in real time according to a linear equation according to the voltage difference between a target voltage and an actual voltage, and the dynamic performance of the DCDC is improved. When the pressure difference is large, the gain of the compensator is improved to accelerate response, and when the pressure difference is small, the gain is reduced to maintain stability. The method has the advantages that software and hardware work cooperatively, the recovery time of DCDC dynamic response can be shortened, and the output drop and overshoot amplitude can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and particularly to a method for improving the dynamic performance of DCDC. Background Art

[0002] In the case of a traditional DCDC converter in a dynamic load scenario, due to the fixed parameters of the loop compensator, when the load changes suddenly, the output voltage will overshoot or drop, and the recovery time is relatively long. For example, when unloading, the output voltage may overshoot by up to 10%, and the recovery time exceeds 200 μs, seriously affecting the system stability. In the prior art, a PI controller with fixed parameters is difficult to balance the dynamic response speed and the steady-state accuracy, and there is an urgent need for an improved solution that combines software and hardware.

[0003] Therefore, it is necessary to provide a method for improving the dynamic performance of DCDC, in which software and hardware work together to shorten the dynamic recovery time and reduce the amplitude of output drop and overshoot. Summary of the Invention

[0004] The present invention discloses a method for improving the dynamic performance of DCDC, belonging to the technical field of switching power supply control, and particularly relating to a dynamic response optimization control method applicable to a DCDC converter, which can effectively solve the technical problems involved in the background art.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for improving the dynamic performance of DCDC includes the following steps:

[0007] S1. The DCDC output voltage is sampled by a sampling circuit, and the MCU uses the sampling result for loop operation and adjusts the duty cycle of the DCDC switching tube according to the operation result.

[0008] S2. A differential line is added to the sampling circuit, and the differential line is a resistor R3 in series with a capacitor C1.

[0009] S3. In the loop control, a proportional parameter y (i.e., Kp) is used, y = kx + b, where x is the difference between the sampled value and the target value of the output voltage, and k and b are constants, which are set according to the debugging results.

[0010] The present invention proposes a control method combining linear gain and differential line, a control method of enhancing the sampling signal by software dynamic gain adjustment and hardware differential line. A first-order RC differential circuit is added at the output voltage sampling end to preferentially capture the voltage mutation signal and feedback it to the controller. The controller adjusts the proportional coefficient of the loop compensator in real time according to the pressure difference between the target voltage and the actual voltage according to a linear equation, so as to increase the compensator gain to accelerate the response when the pressure difference is large, and reduce the gain to maintain stability when the pressure difference is small. Software and hardware work together to shorten the dynamic recovery time and reduce the amplitude of output drop and overshoot.

[0011] As a preferred improvement of the present invention: The DCDC includes a main circuit, the main circuit includes a port DC, one end of the port DC is connected to one end of an inductor L1, the other end of the inductor L1 is connected to pin 3 of a switching transistor Q1 and the positive terminal of a diode D, the negative terminal of the diode D is connected to one end of a capacitor Co and one end of a resistor RL, the other end of the port DC is connected to port GND, pin 2 of the switching transistor Q1, the other end of the capacitor Co and the other end of the resistor RL, and pin 1 of the switching transistor Q1 is connected to the MCU.

[0012] As a preferred improvement of the present invention: The switching transistor Q1 is a MOS transistor, where pin 1 is the gate, pin 2 is the source, and pin 3 is the drain.

[0013] As a preferred improvement of the present invention: The sampling circuit includes a resistor R1, one end of the resistor R1 is connected to the output end of the DCDC and one end of a resistor R3, the other end of the resistor R3 is connected to one end of a capacitor C1, the other end of the resistor R1 is connected to one end of a resistor R2, the other end of the capacitor C1 and one end of a resistor R4, the other end of the resistor R2 is connected to port GND, the other end of the resistor R4 is connected to one end of a capacitor C2 and the MCU, and the other end of the capacitor C2 is connected to port GND.

[0014] As a preferred improvement of the present invention: The MCU uses a PI loop compensator.

[0015] As a preferred improvement of the present invention: The y represents the proportional parameter Kp. PI is a kind of loop compensator (proportional integral control), and Kp is the proportional coefficient of the loop compensator.

[0016] As a preferred improvement of the present invention: The k takes a value of 1 - 2.

[0017] As a preferred improvement of the present invention: The b takes a value of 0.1 - 0.6.

[0018] As a preferred improvement of the present invention: The y has a value range of 0.5 - 5, and x is a positive number or 0.

[0019] The beneficial effects of the present invention are as follows:

[0020] This invention patent is applicable to the field of digital switching power supply technology, and provides a control method that combines linear gain with a differential circuit to improve the dynamic response ability of DCDC. By dynamically adjusting the linear gain parameter (Kp) of the loop compensator through software and adding a differential circuit in the hardware sampling circuit, the overshoot and undershoot of the output voltage during dynamic load changes are significantly reduced, the recovery time is shortened, and the system stability is improved. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings, where:

[0022] Figure 1 It is a schematic diagram of the principle of a method for improving the dynamic performance of DCDC according to the present invention. Specific embodiments

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0025] In addition, in the present invention, descriptions such as "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0026] In the present invention, unless otherwise clearly defined and limited, terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0027] 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 this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0028] See also Figure 1 As shown, Figure 1 The control block diagram includes a differential circuit module, a dynamic gain adjustment module, and a DCDC main circuit. The main circuit includes a port DC, one end of which is connected to one end of the inductor L1, the other end of which is connected to pin 3 of the switch tube Q1 and the positive end of the diode D, the negative end of the diode D is connected to one end of the capacitor Co and one end of the resistor RL, the other end of the port DC is connected to port GND, pin 2 of the switch tube Q1, the other end of the capacitor Co, and the other end of the resistor RL, and pin 1 of the switch tube Q1 is connected to the MCU. Preferably, the switch tube Q1 is a MOS tube, where pin 1 is the gate, pin 2 is the source, and pin 3 is the drain. The sampling circuit includes a resistor R1, one end of which is connected to the output terminal of the DCDC and one end of a resistor R3. The other end of the resistor R3 is connected to one end of a capacitor C1. The other end of the resistor R1 is connected to one end of a resistor R2, the other end of the capacitor C1, and one end of a resistor R4. The other end of the resistor R2 is connected to a GND port. The other end of the resistor R4 is connected to one end of a capacitor C2 and the MCU. The other end of the capacitor C2 is connected to a GND port. It should be further noted that the use of other components to achieve the above-mentioned effects should fall within the inventive concept and the scope of protection of the present invention.

[0029] The present invention provides a method for improving the dynamic performance of DC-DC converters, comprising the following steps:

[0030] S1, the DCDC output voltage is sampled by the sampling circuit, and the MCU uses the sampling result to perform loop calculation and adjusts the duty cycle of the DCDC switch tube in real time according to the calculation result; in this embodiment, the MCU uses a PI compensator to calculate the loop.

[0031] S2. Add a differential circuit to the sampling circuit. The differential circuit is a resistor R3 connected in series with a capacitor C1.

[0032] S3. The proportional parameter y is used in the loop control, y = kx + b, where x is the difference between the sampled output voltage and the target value, and k and b are constants that can be set by the user. In this embodiment, y represents the proportional parameter Kp, k is 1-2, b is 0.1-0.6, y is in the range of 0.5-5, and x is a positive number or 0.

[0033] A control method for improving the dynamic response ability of DCDC by combining linear gain with a differential circuit. The digital loop compensator adopts a processing method that combines linear gain control with output voltage sampling to increase the differential circuit, and the two work together. Software control utilizes the design logic of the linear equation y = kx + b to dynamically adjust the proportional parameter Kp of the loop compensator (PI) according to the pressure difference between the target voltage and the actual voltage, so that its gain changes linearly with the pressure difference. By restricting the value range of Kp (for example, 0.5 ≤ Kp ≤ 5.0), system oscillation or slow response caused by too large or too small gain can be avoided. Hardware connects a first-order RC differential circuit in series in the sampling circuit, extracts the mutation component of the output voltage and feeds it back to the controller to enhance the response speed of the system to dynamic load changes and shorten the adjustment time. Through the cooperation of software gain adjustment and the hardware differential circuit, when the load suddenly changes, the differential circuit feeds back the mutation component of the output voltage to the controller, and at the same time the software dynamically optimizes Kp of the compensator to accelerate the steady-state recovery.

[0034] Working principle:

[0035] Connect an RC differential circuit (such as Figure 1 ) in series at the output voltage sampling terminal, superimpose the differential signal on the original sampling signal and then input it to the controller; in the digital controller (MCU), calculate the pressure difference ΔV between the target voltage Vref and the actual voltage Vout in real time, dynamically adjust the proportional coefficient according to Kp = k * ΔV + b (where the coefficients k and b are set according to the actual situation), and limit Kp within a suitable [Min, Max] range. When the load current suddenly increases or changes, the differential circuit quickly detects the drop or overshoot of Vout and feeds it back to the controller. The controller linearly adjusts Kp synchronously according to the error, quickly adjusts the PWM, and quickly adjusts the output voltage to a stable state.

[0036] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the examples shown and described here.

Claims

1. A method for improving the dynamic performance of DCDC, characterized in that, It includes the following steps: S1. The output voltage of the DCDC is sampled by a sampling circuit. The MCU uses the sampling result for loop operation and adjusts the duty cycle of the DCDC switching tube according to the operation result. S2. A differential circuit is added to the sampling circuit. The differential circuit is a resistor R3 in series with a capacitor C1. S3. The proportional parameter y is used in the loop control, y = kx + b, where x is the difference between the sampled value and the target value of the output voltage, and k and b are constants and are set by oneself.

2. The method for improving the dynamic performance of DCDC according to claim 1, characterized in that: The DCDC includes a main circuit. The main circuit includes a port DC. One end of the port DC is connected to one end of an inductor L1. The other end of the inductor L1 is connected to pin 3 of a switching tube Q1 and the positive end of a diode D. The negative end of the diode D is connected to one end of a capacitor Co and one end of a resistor RL. The other end of the port DC is connected to port GND, pin 2 of the switching tube Q1, the other end of the capacitor Co, and the other end of the resistor RL. Pin 1 of the switching tube Q1 is connected to the MCU.

3. A method for improving the dynamic performance of DCDC according to claim 2, characterized in that: The switching tube Q1 is a MOS tube, where pin 1 is the gate, pin 2 is the source, and pin 3 is the drain.

4. A method for improving the dynamic performance of DCDC according to claim 1, characterized in that: The sampling circuit includes a resistor R1. One end of the resistor R1 is connected to the output end of the DCDC and one end of the resistor R3. The other end of the resistor R3 is connected to one end of the capacitor C1. The other end of the resistor R1 is connected to one end of a resistor R2, the other end of the capacitor C1, and one end of a resistor R4. The other end of the resistor R2 is connected to port GND. The other end of the resistor R4 is connected to one end of a capacitor C2 and the MCU. The other end of the capacitor C2 is connected to port GND.

5. A method for improving the dynamic performance of DCDC according to claim 1, characterized in that: The MCU uses a PI loop compensator.

6. A method for improving the dynamic performance of DCDC according to claim 5, characterized in that: The y represents the proportional parameter Kp.

7. A method for improving the dynamic performance of DCDC according to claim 6, characterized in that: The value of k ranges from 1 to 2.

8. A method for improving the dynamic performance of DCDC according to claim 6, characterized in that: The value of b ranges from 0.1 to 0.

6.

9. A method for improving the dynamic performance of DCDC according to claim 6, characterized in that: The value range of y is from 0.5 to 5, and x is a positive number or 0.

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