Four-phase interleaved boost circuit control method and control device using observer and preset time sliding mode control technology

Abstract

The four-phase interleaved parallel Boost circuit control method using an observer and a preset time sliding mode control technology comprises the following steps: collecting original sampling values of the four-phase interleaved parallel Boost circuit, wherein the original sampling values include input voltage, output voltage and inductance current of each phase; calculating four-phase average current, voltage error and error integral term based on the original sampling values; estimating system real-time disturbance based on the input voltage, the output voltage, the four-phase average current and the control parameters of the last period by using a specified time disturbance observer constructed in advance to obtain a first disturbance estimation value and a second disturbance estimation value; calculating a reference current value according to the voltage error, the error integral term, the output voltage and the second disturbance estimation value; and calculating the control parameters of the current period according to the four-phase average current, the reference current value, the input voltage, the output voltage and the first disturbance estimation value by using an adaptive approach law. The present application can reduce the loss, quickly and stably track the reference voltage and improve the power quality.

Description

Technical Field

[0001] This invention relates to the field of four-phase interleaved parallel Boost circuit technology, specifically to a control method and control device for four-phase interleaved parallel Boost circuits using an observer and preset time sliding mode control technology. Background Technology

[0002] Multiphase interleaved Boost converters are switching power converters that combine small size, high power, and cost-effectiveness. With their unique inherent characteristics, such as minimal output voltage fluctuations and stable input current, they have been widely used in power electronics and microgrids, becoming ideal power supply solutions. However, with the increasing demands for extreme power density and high-capacity transmission in modern new energy microgrids and high-power DC charging piles, the current stress on single inductors and switching devices in the Boost circuit structure is significant under ultra-high power conditions, inevitably leading to difficulties in thermal management. In contrast, multiphase interleaved parallel Boost converters can further distribute current stress by optimizing the conduction logic of multiphase switches. However, considering the large device size due to the high number of interleaved parallel phases, most applications consider four-phase interleaved parallel Boost converters as the core topology.

[0003] Existing control methods for Boost converters mostly consider the uncertainty of the system's mathematical model parameters to achieve robustness and stability against external inputs. The control methods are relatively simple. However, since Boost converters themselves have higher losses and larger output ripples compared to interleaved parallel Boost converters, and using traditional control theory for modeling and control is difficult to meet the requirements for fast and stable output voltage in some scenarios. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a control method and device for a four-phase interleaved parallel Boost circuit that utilizes an observer and a preset time sliding mode control technique. This method reduces losses and designs a time-specified disturbance observer to ensure rapid and stable tracking of the reference voltage under external disturbance conditions, thereby improving power quality and energy utilization.

[0005] To achieve the above objectives, the specific solution adopted by the present invention is as follows: a four-phase interleaved parallel Boost circuit control method employing an observer and preset time sliding mode control technology, comprising: The raw sample values ​​of the four-phase interleaved parallel Boost circuit are collected. The raw sample values ​​include the input voltage, output voltage and inductor current of each phase. Calculate the four-phase average current and voltage error, as well as the error integral term, based on the original sampled values; Using a pre-built time-specified disturbance observer, the real-time disturbance of the system is estimated based on the input voltage, output voltage, four-phase average current, and control parameters of the previous cycle, and the first and second disturbance estimates are obtained. The reference current value is calculated based on the voltage error, the error integral term, the output voltage, and the estimated value of the second interference. The control parameters for the current cycle are calculated using an adaptive approach law based on the four-phase average current, reference current value, input voltage, output voltage, and the estimated value of the first disturbance. A PWM control signal is generated based on the control parameters of the current cycle, and the PWM control signal is used to control the switching transistors in the four-phase interleaved parallel Boost circuit.

[0006] As a further optimization of the four-phase interleaved parallel Boost circuit control method using the observer and preset time sliding mode control technology: the specified time disturbance observer includes a first observer, which is used to perform real-time estimation and feedforward compensation of input voltage fluctuations and model error disturbances. The first observer is: ; in, The average current of the four phases. For current estimation error, This is the damping adjustment coefficient. For constant terms, , , It is a positive number. For time-varying gain, where It is an integer. For a pre-set time constant, This is the switching function.

[0007] As a further optimization of the above-mentioned four-phase interleaved parallel Boost circuit control method using observers and preset time sliding mode control technology, the calculation method of the time-varying gain is as follows: ; The switching function is calculated as follows: .

[0008] As a further optimization of the four-phase interleaved parallel Boost circuit control method using the observer and preset time sliding mode control technology: the specified time disturbance observer includes a second observer, which is used to perform real-time estimation and feedforward compensation of load disturbances. The second observer is: ; in, For output voltage, This represents the voltage estimation error.

[0009] As a further optimization of the four-phase interleaved parallel Boost circuit control method using the observer and preset time sliding mode control technology, the method for calculating the reference current value based on voltage error, error integral term, output voltage, and second disturbance estimate includes: The convergence time function value is calculated based on the preset sliding surface. ,in To preset the convergence time, To adjust the parameters; Calculate the reference current value .

[0010] As a further optimization of the four-phase interleaved parallel Boost circuit control method using the observer and preset time sliding mode control technology, the sliding surface is: .

[0011] As a further optimization of the four-phase interleaved parallel Boost circuit control method using the observer and preset time sliding mode control technology, the adaptive reaching law is: ; in, For fixed gain, Follow-up error An adaptive adjustment function, and has ,in , It is a positive integer.

[0012] A control device for a four-phase interleaved parallel Boost circuit employing an observer and a preset time sliding mode control technique is provided to implement the aforementioned control method for a four-phase interleaved parallel Boost circuit employing an observer and a preset time sliding mode control technique. The device comprises: The data acquisition module is used to acquire the input voltage, output voltage, and inductor current of the converter; The interference observation module is used to estimate system disturbances in real time based on the data collected by the data acquisition module. The dual closed-loop control module is used to calculate the control duty cycle based on the data acquired by the data acquisition module and the disturbance estimated by the disturbance observation module, through the outer loop preset time sliding mode control and the inner loop adaptive approach law control. The PWM generation module is used to generate multiple PWM signals with preset phase differences according to the control duty cycle, and drive the corresponding switching transistors.

[0013] Beneficial Effects: This invention establishes a dual-closed-loop preset-time sliding mode controller based on a specified-time disturbance observer, preset-time control, and adaptive reaching law control theory. The specified-time disturbance observer is used to estimate the load resistance, input voltage, and disturbances in the unmodeled parts of the system in real time, improving the disturbance rejection capability and stability of the four-phase interleaved parallel Boost converter output. By constructing an outer-loop preset-time sliding mode control and an inner-loop control design combining an adaptive reaching law, the convergence speed of the converter system is effectively improved. It can stably track changes in the reference voltage and exhibits less chattering in the output voltage fluctuations. Attached Figure Description

[0014] Figure 1 This is a design diagram of the control framework for the four-phase interleaved parallel Boost converter of this invention; Figure 2 This is a simulation result diagram of the overall controller. Detailed Implementation

[0015] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] like Figure 1 and Figure 2 As shown, the present invention first provides a control method for a four-phase interleaved parallel Boost circuit using an observer and a preset time sliding mode control technique, including S1 to S6.

[0017] S1. Collect the raw sample values ​​of the four-phase interleaved parallel Boost circuit. The raw sample values ​​include the input voltage, output voltage, and inductor current of each phase.

[0018] S2. Calculate the four-phase average current, voltage error, and error integral term based on the original sampled values.

[0019] S3. Using a pre-built disturbance observer at a specified time, estimate the real-time disturbance of the system based on the input voltage, output voltage, four-phase average current and control parameters of the previous cycle, and obtain the first disturbance estimate and the second disturbance estimate.

[0020] S4. Calculate the reference current value based on the voltage error, the error integral term, the output voltage, and the second interference estimate.

[0021] S5. Calculate the control parameters for the current cycle using the adaptive approach law based on the four-phase average current, reference current value, input voltage, output voltage, and the first disturbance estimate.

[0022] S6. Generate a PWM control signal based on the control parameters of the current cycle, and use the PWM control signal to control the switching transistors in the four-phase interleaved parallel Boost circuit.

[0023] Furthermore, the specified time disturbance observer includes a first observer, which is used to perform real-time estimation and feedforward compensation of input voltage fluctuations and model error disturbances. The first observer is: ; in, The average current of the four phases. For current estimation error, This is the damping adjustment coefficient. For constant terms, , , It is a positive number. For time-varying gain, where It is an integer. For a pre-set time constant, This is the switching function.

[0024] Furthermore, the method for calculating the time-varying gain is as follows: ; The switching function is calculated as follows: .

[0025] Furthermore, the specified time disturbance observer includes a second observer, which is used to perform real-time estimation and feedforward compensation of load disturbances. The second observer is: ; in, For output voltage, This represents the voltage estimation error.

[0026] Furthermore, the method for calculating the reference current value based on the voltage error, the error integral term, the output voltage, and the second interference estimate includes: The convergence time function value is calculated based on the preset sliding surface. ,in To preset the convergence time, To adjust the parameters; Calculate the reference current value .

[0027] The sliding surface is: .

[0028] The adaptive reaching law is: ; in, For fixed gain, Follow-up error An adaptive adjustment function, and has ,in , It is a positive integer.

[0029] The method of the present invention will be further described in detail below.

[0030] First, this invention establishes a state-space model of a four-phase interleaved parallel Boost DC-DC converter and transforms the average state-space equations of the system. Specifically, as follows.

[0031] The four-phase interleaved parallel Boost converter topology consists of four Boost circuits connected in parallel. The operating mode analysis of the four-phase interleaved parallel Boost converter includes the switching transistors of each branch. On or off state analysis: ; in, This is the capacitance value. This is the inductance value. This is the resistance value. For inductor current, Input voltage, The output voltage is where Or 0, The value is determined by the switching transistor of the corresponding inductor circuit. Whether it conducts or not is determined by the switch transistor; if the corresponding switch transistor is off, then... Conversely, it is 0; similarly, The value of is also determined by this; it is 0 if the circuit is on and 0 if it is off. .

[0032] Combining the state equations of the energy storage inductors and capacitors for each switch being turned on or off, let Using these signals as control signals for the four switching transistors respectively, the mathematical model of the converter is obtained as follows: .

[0033] Furthermore, before designing the controller, the four-phase interleaved parallel Boost circuit system must first meet the inductance requirements of each branch. Considering that the switching frequency is the same in each phase, the average model can be rewritten as follows: ; in, , and These are the equivalent inductance, average current, and average output signal of the controller, respectively. This represents input voltage fluctuations and model error disturbances. This includes load variations and unmodeled disturbances.

[0034] Second, this invention introduces a time-defined disturbance observer to estimate the disturbance at a specified time point. A special time adjustment function design ensures the boundedness of the state variables, simplifying the design of the switching controller. Details are as follows.

[0035] Based on the average mathematical model obtained in S1, a Specified Time Disturbance Observer (STDOB-I), the first observer, was designed to estimate and feedforward the input voltage fluctuations and model error disturbances in real time, completely overcoming the conservatism of the convergence time of traditional observers. Furthermore, a Specified Time Disturbance Observer (STDOB-II), the second observer, was designed to estimate and feedforward the load disturbances in real time.

[0036] Furthermore, according to the average model The STDOB-I is designed as follows: ; in, This is an estimate of the average inductor current. For current estimation error, This is the damping coefficient, used to adjust the dynamic characteristics of STDOB-I. It is a constant value. , , It is a very small positive number; time-varying gain Defined as: ; in, It is a very small integer, used to prevent the denominator from being 0. A pre-set time constant; The value of is 0 or 1, and it is defined as:

[0037] Depend on As can be seen from the definition, the convergence time of an observer based on specified time adjustment is achieved through... The parameters It is directly set, that is, the observer's estimation error is within a preset time point. Convergence is achieved, and the convergence time is unaffected by the system's initial state or other parameters. Because... Therefore, consider the function Only It is defined that when hour, The observer switches its structure to ensure that the tracking error is within the range of... It can still remain at zero point, thus achieving accurate estimation of interference signals.

[0038] Furthermore, in terms of output voltage Construct a second-order observer for the output variable. As a state variable, STDOB-II is designed as follows: ; in, This is an estimate of the output voltage. This is to estimate the error. That is, when time... hour, At this point, the time function in STDOB-II begins to monotonically increase, rapidly reducing the initial estimation error to near the origin. And when... hour, This can be expressed as: ; because The time-varying gain of the stage has quickly converged to the estimation error, so the observer structure of the above stage can enable its system to converge to the estimation error near zero.

[0039] Third, by employing a dual-closed-loop preset time sliding mode control structure, this invention improves the fast response capability of the DC-DC converter, meeting the power requirements of the DC-DC converter in some high-power scenarios. Details are as follows.

[0040] Define output voltage tracking error .

[0041] in, The system output voltage is set to a constant reference value. To achieve convergence within a preset time, the sliding surface is designed as follows:

[0042] in, The preset time convergence function is expressed as follows: ; in, To preset the convergence time, To adjust the parameters.

[0043] To achieve sliding surface To converge to zero, a current inner loop reference signal needs to be designed. , making It satisfies the expected convergence law. Taking the derivative with respect to the sliding surface, we get: ; From the average mathematical model of the four-phase interleaved parallel Boost circuit, we can obtain: .

[0044] Considering that the dynamic response of the inner current loop is much faster than that of the voltage loop, the average inductor current can be set. Able to track the reference current signal instantaneously, that is Set the virtual control variable as follows: ; The dynamic equation for the output voltage is redefined as follows: We can obtain: .

[0045] To avoid directly affecting virtual control quantities Differentiation is achieved through a direct design based on the Lyapunov function method. First, the integration term is introduced as follows: Secondly, the Lyapunov function is constructed as follows: ,in, ,right Taking the derivative, we get: .

[0046] Considering the actual controller output signal It is unknown whether, in the inner and outer loop cascade control structure, the inner current loop will force the inductor current to track. ,at this time Determined by the current loop, and when the current loop bandwidth is sufficiently high, it can be approximated. Therefore, in order to make The derivative is negative definite and satisfies the preset time control, set as follows: ; Obtain the reference current signal for: .

[0047] The specific steps of the current inner loop controller are as follows: First, define the current tracking error: From the current equation of the converter, we can obtain: ; in, This includes input voltage disturbances, inductor parameter uncertainties, and unmodeled dynamic characteristics. Estimates provided by STDOB-I are used. Differentiating the current error and substituting it into the equation, we obtain the dynamic equation for the current error: ; Therefore, it is necessary to design control inputs. Make error It can converge quickly to zero, and the adaptive reaching law expression is designed as follows: ; in, For fixed gain, To follow the error The adaptive adjustment function is expressed as: ; in, , , For positive integers, It is a very small positive integer, to prevent the denominator from being zero.

[0048] when When it is large, At this point, the reaching law is approximately: This ensures rapid convergence; while when When it is smaller, at this time The approach law is approximately as follows: This eliminates chattering and ensures system stability. Substituting the adaptive reaching law into the current error dynamic equation yields: ; The controller output signal is obtained by solving the equation. for: .

[0049] At this time, the control signal obtained The controller design is completed by introducing PWM signals into the switching transistors with a 90° phase difference.

[0050] To verify the method of the present invention, simulations were performed using existing simulation software, and the results are as follows. Figure 2 As shown, from Figure 2 It can be seen that, after control based on the present invention, the stability of the four-phase interleaved parallel Boost circuit is significantly improved.

[0051] The present invention further provides a control device for a four-phase interleaved parallel Boost circuit using an observer and a preset time sliding mode control technique, for implementing the above-mentioned control method for a four-phase interleaved parallel Boost circuit using an observer and a preset time sliding mode control technique. The device includes a data acquisition module, an interference observation module, a dual closed-loop control module, and a PWM generation module.

[0052] The data acquisition module is used to acquire the input voltage, output voltage, and inductor current of the converter; The interference observation module is used to estimate system disturbances in real time based on the data collected by the data acquisition module. The dual closed-loop control module is used to calculate the control duty cycle based on the data acquired by the data acquisition module and the disturbance estimated by the disturbance observation module, through the outer loop preset time sliding mode control and the inner loop adaptive approach law control. The PWM generation module is used to generate multiple PWM signals with preset phase differences according to the control duty cycle, and drive the corresponding switching transistors.

[0053] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a four-phase interleaved parallel Boost circuit employing an observer and preset time sliding mode control technology, characterized in that, include: The raw sample values ​​of the four-phase interleaved parallel Boost circuit are collected. The raw sample values ​​include the input voltage, output voltage and inductor current of each phase. Calculate the four-phase average current and voltage error, as well as the error integral term, based on the original sampled values; Using a pre-built time-specified disturbance observer, the real-time disturbance of the system is estimated based on the input voltage, output voltage, four-phase average current, and control parameters of the previous cycle, and the first and second disturbance estimates are obtained. The reference current value is calculated based on the voltage error, the error integral term, the output voltage, and the estimated value of the second interference. The control parameters for the current cycle are calculated using an adaptive approach law based on the four-phase average current, reference current value, input voltage, output voltage, and the estimated value of the first disturbance. A PWM control signal is generated based on the control parameters of the current cycle, and the PWM control signal is used to control the switching transistors in the four-phase interleaved parallel Boost circuit.

2. The four-phase interleaved parallel Boost circuit control method using an observer and preset time sliding mode control technology as described in claim 1, characterized in that, The specified time disturbance observer includes a first observer, which is used to perform real-time estimation and feedforward compensation of input voltage fluctuations and model error disturbances. The first observer is: ； in, The average current of the four phases. For current estimation error, This is the damping adjustment coefficient. For constant terms, , , It is a positive number. For time-varying gain, where It is an integer. For a pre-set time constant, This is the switching function.

3. The four-phase interleaved parallel Boost circuit control method using an observer and preset time sliding mode control technology as described in claim 2, characterized in that, The method for calculating the time-varying gain is as follows: ； The switching function is calculated as follows: 。 4. The four-phase interleaved parallel Boost circuit control method using an observer and preset time sliding mode control technology as described in claim 1, characterized in that, The specified time disturbance observer includes a second observer, which is used for real-time estimation and feedforward compensation of load disturbances. The second observer is: ； in, For output voltage, This represents the voltage estimation error.

5. The four-phase interleaved parallel Boost circuit control method using an observer and preset time sliding mode control technology as described in claim 1, characterized in that, Methods for calculating the reference current value based on voltage error, error integral term, output voltage, and second interference estimate include: The convergence time function value is calculated based on the preset sliding surface. ,in To preset the convergence time, To adjust the parameters; Calculate the reference current value .

6. The four-phase interleaved parallel Boost circuit control method using an observer and preset time sliding mode control technology as described in claim 5, characterized in that, The sliding surface is: 。 7. The four-phase interleaved parallel Boost circuit control method using an observer and preset time sliding mode control technology as described in claim 1, characterized in that, The adaptive reaching law is: ； in, For fixed gain, Follow-up error An adaptive adjustment function, and has ,in , It is a positive integer.

8. A four-phase interleaved parallel Boost circuit control device employing an observer and preset time sliding mode control technology, characterized in that, The apparatus for implementing the four-phase interleaved parallel Boost circuit control method using an observer and preset time sliding mode control technology as described in any one of claims 1-7 comprises: The data acquisition module is used to acquire the input voltage, output voltage, and inductor current of the converter; The interference observation module is used to estimate system disturbances in real time based on the data collected by the data acquisition module. The dual closed-loop control module is used to calculate the control duty cycle based on the data acquired by the data acquisition module and the disturbance estimated by the disturbance observation module, through the outer loop preset time sliding mode control and the inner loop adaptive approach law control. The PWM generation module is used to generate multiple PWM signals with preset phase differences according to the control duty cycle, and drive the corresponding switching transistors.

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