Low-voltage nonlinear self-adaptive control structure and method for high-power digital power supply

Abstract

The invention discloses a low-voltage nonlinear self-adaptive control structure and method for a high-power digital power supply. The low-voltage nonlinear self-adaptive control structure comprises inner-loop control and outer-loop control, an outer ring is used for making a difference between a set voltage Vset and an output voltage Vback subjected to adaptive oversampling, and an inner ring reference value Iref is output after the difference passes through a PI module; the inner ring reference value Iref is compared with the current sampling value and then passes through a loop compensator of an inner ring and a system topology to output a PWM waveform, and the PWM waveform outputs a proper PWM wave to drive a switching tube under the regulation and control of a nonlinear controller, so as to achieve the purpose of outputting desired voltage or current. The self-adaptive oversampling technology ensures precision and reduces interference caused by fluctuation in high-frequency multiplication sampling in a low-voltage section, and normal sampling is recovered in a steady-state stage, so that memory is saved; and low-voltage steady-state operation is realized on the basis of a classic control structure.

Description

Technical Field

[0001] This invention relates to a switching power supply control technology, and more particularly to a low-voltage nonlinear adaptive control structure and method for a high-power digital power supply. Background Technology

[0002] Currently, with the development and application of digitalization and artificial intelligence, the development, use, and control of high-power, wide-range, and large-scale digital power supplies are urgently needed to meet the demands of modern electronic systems for high efficiency, high power density, high reliability, intelligent management, and flexible configuration. These technologies are fundamental to supporting the development of key fields such as new energy, electric vehicles, data centers, industrial automation, and high-end consumer electronics. The demand for complex structures based on the basic Buck topology—series, parallel, or series-parallel crossovers—to achieve high power, high voltage, and high current is also increasing, leading to a proliferation of control strategies to ensure stability and reliability. Due to the complexity of the overall structure, theoretical compensation or feedforward cannot cover all voltage or frequency ranges. Therefore, low-voltage steady-state control of high-voltage, high-power switching power supplies is a worthy area of ​​research.

[0003] Currently, with the development of digitalization and intelligence, some intelligent control algorithms have also been applied to the field of switching power supplies. There are currently two methods for low-end steady-state optimization control: one is input voltage feedforward, which detects changes in input voltage in real time and adjusts the duty cycle in advance to reduce loop pressure; the other is adaptive compensation, which adjusts PID parameters in real time based on output voltage, load current, etc.

[0004] 1. Input voltage feedforward technical solution:

[0005] like Figure 1 As shown, input voltage feedforward technology is one of the key technologies for solving the low-voltage oscillation problem in high-power digital switching power supplies, especially crucial for suppressing disturbances caused by sudden changes in input voltage. Its core idea is to bypass the feedback loop delay and directly adjust the inner loop input reference in real time according to changes in input voltage, thereby significantly improving dynamic response and stability.

[0006] Disadvantages of input voltage feedforward technology:

[0007] Coupled oscillations with loop control: If the feedforward signal is too strong or mismatched with the feedback loop delay, it may cause control-coupled oscillations. For example, in digital control, computational delays can cause the feedforward action and feedback response to be out of sync, thus amplifying disturbances.

[0008] For constant power loads (negative impedance characteristics), feedforward may exacerbate loop instability, requiring the use of output impedance reshaping technology.

[0009] Insufficient compensation for wide input voltage range: A single feedforward coefficient cannot cover a wide input range (such as 200V-1500V), and segmented adjustment or adaptive algorithm is required. Otherwise, oscillation may occur at the high-low voltage switching point, and even the lowest duty cycle will not meet the requirements.

[0010] 2. Adaptive compensation technical solution:

[0011] The core of adaptive compensation technology lies in adjusting control parameters in real time to adapt to changes in system operating conditions (such as input voltage fluctuations, load changes, temperature drift, etc.). Although it can significantly improve system robustness, it still has several inherent drawbacks. Figure 1 The PI control module in the system does not use a single parameter, but rather a parameter that changes in real time according to the actual situation.

[0012] Disadvantages of adaptive compensation:

[0013] Convergence delay leads to transient oscillations: parameter adjustment requires iterative calculations. Under sudden changes, the system becomes unstable before the adaptive process is completed. Multiple sets of fixed parameter tables need to be pre-set for emergency switching, increasing storage resources.

[0014] The contradiction between computational complexity and real-time performance: If high-precision adaptive computation is used, it cannot be run in real time on a low-cost MCU.

[0015] Noise sensitivity and risk of misjudgment: In harsh EMI environments (such as motor drives), adaptive algorithms may misjudge noise as changes in operating conditions, triggering parameter oscillations.

[0016] In view of this, the present invention is hereby proposed. Summary of the Invention

[0017] The purpose of this invention is to provide a low-voltage nonlinear adaptive control structure and method for high-power digital power supplies to solve the aforementioned technical problems in the prior art.

[0018] The objective of this invention is achieved through the following technical solution:

[0019] The high-power digital power supply low-voltage nonlinear adaptive control structure of the present invention includes an inner loop control unit and an outer loop control unit;

[0020] The outer loop control unit includes an adaptive oversampling unit, which is connected between the set voltage Vset input terminal and the voltage or current output terminal. The set voltage Vset input terminal is connected to the PI module.

[0021] The inner loop control unit includes an inner loop reference value Iref unit and a PWM module. The inner loop reference value Iref unit is connected to the voltage or current output terminal.

[0022] The PI module is connected to the inner loop reference value Iref unit.

[0023] The control method for the above-mentioned high-power digital power supply low-voltage nonlinear adaptive control structure includes inner-loop control and outer-loop control.

[0024] The outer loop is the difference between the set voltage Vset and the output voltage Vback after adaptive oversampling. The difference is output by the PI module as the inner loop reference value Iref.

[0025] The inner loop reference value Iref is compared with the current sampling value and then outputs a PWM waveform through the inner loop compensator and system topology. Under the control of the nonlinear controller, the PWM waveform outputs a suitable PWM wave to drive the switching transistor, thereby achieving the desired output voltage or current.

[0026] Compared with existing technologies, the high-power digital power supply low-voltage nonlinear adaptive control structure and method provided by this invention realizes frequency conversion control of the switching frequency in the low-voltage segment based on nonlinear control; it uses adaptive oversampling technology to ensure accuracy and reduce interference caused by fluctuations by sampling at high multiples in the low-voltage segment, and restores normal sampling in the steady-state stage to save memory; and it realizes low-voltage steady-state operation based on the classic control structure. Attached Figure Description

[0027] Figure 1 This is a block diagram of the input voltage feedforward control in the prior art.

[0028] Figure 2 This is a schematic diagram of the digital control principle in an embodiment of the present invention.

[0029] Figure 3 This is a block diagram of digital control according to an embodiment of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them, and do not constitute a limitation on the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0031] First, the following explanations are provided for the terms that may be used in this article:

[0032] The terms “including,” “contains,” “comprising,” “having,” or other similar semantic descriptions shall be interpreted as non-exclusive inclusion.

[0033] The contents not described in detail in the embodiments of this invention are prior art known to those skilled in the art. Where specific conditions are not specified in the embodiments of this invention, they shall be performed according to conventional conditions in the art or conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments used in the embodiments of this invention are not specified, they are all conventional products that can be purchased commercially.

[0034] The high-power digital power supply low-voltage nonlinear adaptive control structure of the present invention includes an inner loop control unit and an outer loop control unit;

[0035] The outer loop control unit includes an adaptive oversampling unit, which is connected between the set voltage Vset input terminal and the voltage or current output terminal. The set voltage Vset input terminal is connected to the PI module.

[0036] The inner loop control unit includes an inner loop reference value Iref unit and a PWM module. The inner loop reference value Iref unit is connected to the voltage or current output terminal.

[0037] The PI module is connected to the inner loop reference value Iref unit.

[0038] The PWM module is connected to the nonlinear controller.

[0039] The control method for the above-mentioned high-power digital power supply low-voltage nonlinear adaptive control structure includes inner-loop control and outer-loop control.

[0040] The outer loop is the difference between the set voltage Vset and the output voltage Vback after adaptive oversampling. The difference is output by the PI module as the inner loop reference value Iref.

[0041] The inner loop reference value Iref is compared with the current sampling value and then outputs a PWM waveform through the inner loop compensator and system topology. Under the control of the nonlinear controller, the PWM waveform outputs a suitable PWM wave to drive the switching transistor, thereby achieving the desired output voltage or current.

[0042] The adaptive oversampling includes:

[0043] The power supply uses a high frequency sampling rate when operating at low voltage, so that effective data can be collected even under interference conditions. However, the amount of data processing is slightly larger at this time.

[0044] Under high voltage conditions, the system itself is in a state with a high stability margin, so low frequency sampling is used, which results in a smaller amount of data processing.

[0045] The nonlinear controller:

[0046] A voltage threshold is set according to the characteristics of the digital power supply. When the voltage of the power supply drops to this threshold when it is operating at a constant voltage, a trigger signal is generated. This signal tells the PWM module to reduce the frequency of the output drive waveform.

[0047] By reducing the frequency of the PWM waveform, the control cycle is lengthened, the oscillation frequency is reduced, and effective stable control is achieved without affecting the overall dynamics and ripple of the system.

[0048] In summary, the high-power digital power supply low-voltage nonlinear adaptive control structure and method of this invention is a nonlinear adaptive control technology. It achieves frequency conversion control of the switching frequency in the low-voltage segment based on nonlinear control; it uses adaptive oversampling technology to sample at high multiples of frequency in the low-voltage segment to ensure accuracy and reduce interference caused by fluctuations; it restores normal sampling in the steady-state stage to save memory; and it achieves low-voltage steady-state operation based on the classic control structure.

[0049] It solves the problem that traditional control methods cannot achieve stable low-voltage output and anti-interference of digital power supplies with a wide range and large range; it also solves the problems of feedback delay, low accuracy and high computational complexity of traditional control methods within a certain range; and it increases the robustness and reliability of the system.

[0050] To more clearly demonstrate the technical solution and its effects provided by the present invention, the embodiments of the present invention will be described in detail below with reference to specific examples.

[0051] Example 1

[0052] like Figure 2 , Figure 3 As shown:

[0053] This invention adds a nonlinear controller and adaptive oversampling technology to the traditional inner loop current and outer loop voltage loop.

[0054] The key points of basic oversampling techniques are as follows:

[0055] Theorem 1: For every four times increase in sampling frequency, one bit of precision is added.

[0056] Theorem 1 shows that to obtain an additional p-bit precision, the sampling frequency needs to be increased by 4^p.

[0057] Theorem 2: Use the sampled values ​​obtained through an oversampling rate of 4^p.

[0058] 1) Summation, resulting in a value with R+2p bits (R being the previous precision).

[0059] 2) Shift right by p bits. After shifting right, you will get a value of R+p bits. This value is the sampling result with p-bit precision.

[0060] Adaptive oversampling technique:

[0061] The power supply uses a high frequency sampling rate (4^p, where p takes the largest value) when operating at low voltage. At this time, effective data acquisition can be achieved even under interference conditions, but the data processing volume is slightly larger. However, when the system is operating at high voltage, it is in a state with a high stability margin, so a low frequency sampling rate (4^p, where p takes the smallest value, with the minimum value being 0) is used, and the data processing volume is smaller.

[0062] Nonlinear controller:

[0063] A voltage threshold can be flexibly set based on the characteristics of the digital power supply. When the voltage drops to this threshold during constant-voltage operation, a trigger signal is generated, instructing the PWM module to reduce the frequency of the output drive waveform. Experiments show that during low-voltage oscillation, the PWM drives the transistors with high-frequency large and small waves at the switching frequency, making it difficult for the system to reach a steady state. By reducing the frequency of the PWM waveform, the control cycle is lengthened, and the oscillation frequency is reduced, achieving effective stable control without affecting the overall system dynamics and ripple.

[0064] The principle block diagram of this invention is described as follows:

[0065] Figure 2 It is divided into inner loop control and outer loop control. The outer loop calculates the difference between the set voltage Vset and the output voltage Vback after adaptive oversampling. The difference is output by the PI module as the inner loop reference value Iref. The inner loop reference value Iref is compared with the current sampling value and then output as a PWM waveform through the inner loop compensator and the system topology. Under the control of the nonlinear controller, the PWM waveform outputs a suitable PWM wave to drive the switching transistor to achieve the desired output voltage or current.

[0066] The beneficial effects of the technical solution of this invention are as follows:

[0067] Because this invention uses adaptive oversampling technology to increase sampling accuracy and improve system anti-interference and stability at low voltage and low steady state, and to switch to normal sampling at high voltage and high stability margin, it can save system memory and reduce computation. Based on system needs, it is targeted and saves memory and cost.

[0068] Because the circuit of this invention uses a nonlinear controller to regulate the output frequency of the PWM module, the voltage ripple decreases at low voltages, the system can easily reach stability, the control is simplified, and a stable output of a wide-range, large-scale digital switching power supply is achieved. It also reduces component losses and extends the service life.

[0069] Advanced control algorithms are implemented by leveraging the advantages of digital control in traditional classical control topologies, thereby increasing the robustness, anti-interference capability, and adaptability of digital power supplies.

[0070] In practice:

[0071] The Gc(s) loop compensator in this invention can be a higher-order structure or can introduce current feedforward.

[0072] The control process in this invention can be implemented in one control chip or in two control chips.

[0073] The embedded chip in this invention can be an ARM, DSP, or FPGA, depending on the switching frequency.

[0074] The key technical points of this invention are as follows:

[0075] 1) The adaptive oversampling technology in this scheme can increase sampling accuracy and improve the system's anti-interference and stability when the voltage is low and the steady state is low. When the voltage is high, the system can use ordinary sampling to save system memory.

[0076] 2) A nonlinear controller is used to realize the frequency conversion control of the PWM waveform output by the PWM module in the constant voltage and low voltage working mode of the switching power supply, so as to achieve stable output of the wide range and large range digital switching power supply.

[0077] 3) Using ZYQN as a platform, advanced control algorithms (adaptive oversampling technology and nonlinear frequency conversion control technology) are implemented in the traditional classic control topology by leveraging the advantages of digital control, providing a reliable control system for the system.

[0078] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A low-voltage nonlinear adaptive control structure for a high-power digital power supply, characterized in that, Includes an inner loop control unit and an outer loop control unit; The outer loop control unit includes an adaptive oversampling unit, which is connected between the set voltage Vset input terminal and the voltage or current output terminal. The set voltage Vset input terminal is connected to the PI module. The inner loop control unit includes an inner loop reference value Iref unit and a PWM module. The inner loop reference value Iref unit is connected to the voltage or current output terminal. The PI module is connected to the inner loop reference value Iref unit.

2. The high-power digital power supply low-voltage nonlinear adaptive control structure according to claim 1, characterized in that, The PWM module is connected to the nonlinear controller.

3. A method for implementing control using the low-voltage nonlinear adaptive control structure of a high-power digital power supply as described in claim 1 or 2, characterized in that, Includes inner-loop control and outer-loop control; The outer loop is the difference between the set voltage Vset and the output voltage Vback after adaptive oversampling. The difference is output by the PI module as the inner loop reference value Iref. The inner loop reference value Iref is compared with the current sampling value and then output as a PWM waveform through the inner loop compensator and system topology. Under the control of the nonlinear controller, the PWM waveform outputs a suitable PWM wave to drive the switching transistor, thereby achieving the desired output voltage or current.

4. The method according to claim 3, characterized in that, The adaptive oversampling includes: The power supply uses a high frequency sampling rate when operating at low voltage, so that effective data can be collected even under interference conditions. However, the amount of data processing is slightly larger at this time. Under high voltage conditions, the system itself is in a state with a high stability margin, so low frequency sampling is used, which results in a smaller amount of data processing.

5. The method according to claim 4, characterized in that, The nonlinear controller: A voltage threshold is set according to the characteristics of the digital power supply. When the voltage of the power supply drops to this threshold when it is operating at a constant voltage, a trigger signal is generated. This signal tells the PWM module to reduce the frequency of the output drive waveform. By reducing the frequency of the PWM waveform, the control cycle is lengthened, the oscillation frequency is reduced, and effective stable control is achieved without affecting the overall dynamics and ripple of the system.

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