Bidirectional half-bridge converter switching composite control method and system based on non-smooth super-spiral sliding mode

Abstract

The invention provides a bidirectional half-bridge converter switching composite control method and system based on a non-smooth super-spiral sliding mode, and belongs to the technical field of power electronic converter control. The control method comprises the following steps: respectively establishing nonlinear dynamic models for a Boost mode and a Buck mode, and adopting an accurate feedback linearization technology for the Boost mode to solve a non-minimum phase problem; designing a nonlinear extended state observer, and estimating matching and non-matching lumped disturbance in real time; based on the disturbance estimation value, designing a non-smooth super-spiral sliding mode controller for the two modes respectively, and ensuring finite time convergence; and a smooth switching controller of a bidirectional operation mode is constructed, and seamless switching between a Boost mode and a Buck mode is realized. Under the control method, the bidirectional half-bridge converter is high in anti-interference performance, high in dynamic response speed and capable of effectively restraining buffeting.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology control, specifically relating to a high-performance composite control method for bidirectional half-bridge DC-DC converters, which is particularly suitable for applications such as electric vehicles, battery management, and regenerative braking systems. Background Technology

[0002] With the rapid development of transportation electrification, bidirectional DC-DC converters, as key components for efficient energy management between different DC voltage buses, are increasingly widely used. Despite the simple structure of bidirectional half-bridge converters, achieving high-performance voltage regulation presents significant challenges. First, in boost mode, the converter is a typical non-minimum-phase system, which complicates the direct design of the controller and makes it difficult to guarantee system stability. Second, the converter's dynamic behavior inherently exhibits nonlinearity and time-varying characteristics, especially during the switching between boost and buck modes. Furthermore, the system is inevitably affected by various uncertainties and external disturbances, such as input voltage fluctuations and load abrupt changes, all of which severely impact control accuracy and system stability.

[0003] To address the non-minimum phase problem, existing technologies have proposed various methods, such as exact feedback linearization. The core idea of ​​exact feedback linearization is to transform a complex nonlinear problem into a linear one through coordinate transformation. However, this method relies on an accurate system model and exhibits poor robustness. Sliding mode control is a powerful and robust control technique, insensitive to parameter uncertainties and external disturbances, and is often used in conjunction with exact feedback linearization. However, traditional first-order sliding mode control suffers from chattering, which reduces control accuracy and increases the stress on the power switches.

[0004] To suppress chattering, high-order sliding mode control, especially the superhelical algorithm, is widely used. However, the traditional superhelical algorithm can only attenuate chattering caused by high-frequency switching terms, but cannot completely eliminate it. To further improve the system's disturbance rejection capability, extended state observers are used to estimate the total disturbance, including model uncertainties and external load disturbances, in real time. However, traditional extended state observers amplify measurement noise at high gain, affecting system stability.

[0005] Therefore, there is an urgent need for a new control strategy that can solve the non-minimum phase problem, effectively suppress internal and external disturbances, and eliminate control chattering, in order to meet the application requirements of high-performance bidirectional DC-DC converters. Summary of the Invention

[0006] To address the inherent nonlinearity of bidirectional converters and the chattering problem inherent in traditional superspiral algorithms, this invention proposes a bidirectional half-bridge converter switching composite control method and system based on non-smooth superspiral sliding mode. This method first constructs a smooth switching controller for bidirectional operation modes to achieve seamless switching between Boost and Buck modes. Then, addressing the non-minimum phase characteristics of the converter in Boost mode, it utilizes precise feedback linearization to convert it into a minimum phase system. A nonlinear extended state observer is used to estimate and compensate for matched and unmatched disturbances in real time. A non-smooth superspiral sliding mode controller is designed, replacing discontinuous terms with non-smooth terms to effectively suppress chattering while ensuring finite-time convergence. To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0007] For the Boost mode and Buck mode of the bidirectional half-bridge converter, nonlinear dynamic models including parameter uncertainties and external disturbances are established respectively.

[0008] By redefining the system state variables through nonlinear coordinate transformation, the converter in Boost mode is transformed into a minimum phase system, and then the nonlinear dynamic converter model in Boost mode is transformed into a linearized model.

[0009] For Boost mode and Buck mode, nonlinear extended state observers are designed respectively to estimate the matched and unmatched lumped disturbances caused by input voltage fluctuations and output load changes in real time.

[0010] Based on the linearized model and lumped perturbation estimate of the Boost mode, a composite non-smooth superspiral sliding mode controller is designed for the Boost mode, generating the controller for the Boost mode. ;

[0011] Based on the nonlinear dynamic model and lumped disturbance estimate of Buck mode, a composite nonsmooth superspiral sliding mode controller is designed for Buck mode, generating the controller for Buck mode. ;

[0012] A smooth switching controller for bidirectional operation mode is constructed. The hysteresis width is used to determine the energy flow direction and the working mode of the converter. The final duty cycle control signal is generated through a smooth transition mechanism and applied to the bidirectional half-bridge converter to achieve seamless switching between Boost mode and Buck mode.

[0013] Furthermore, the nonlinear dynamic model of the Boost mode is as follows:

[0014]

[0015] in, This is the output voltage on the high-voltage side. This refers to the inductor current in Boost mode. This is the duty cycle control input for Boost mode. For high-voltage side capacitors, For inductance, This is the nominal value of the low-voltage side load resistance. This is the nominal value of the low-voltage side input voltage. This refers to the lumped disturbance caused by input voltage fluctuations in Boost mode. The lumped disturbance caused by changes in output load in Boost mode is defined as follows:

[0016] ,

[0017] in, This represents the actual load resistance on the low-voltage side. This is the actual input voltage on the low-voltage side.

[0018] Furthermore, the system state variables are redefined as follows: The minimum phase system is: System functions and for: Transformed lumped disturbance and for: , .

[0019] Furthermore, the nonlinear extended state observer for the Boost mode includes:

[0020] Used to estimate disturbances Observer:

[0021]

[0022] Used to estimate disturbances Observer:

[0023]

[0024] in, for The observed values, for The observed values, for The estimated value, for The estimated value, , , , , , , , All are Boost-mode nonlinear extended state observers with adjustable gain.

[0025] Furthermore, the controller for Boost mode for:

[0026]

[0027] in, , , All values ​​are estimates obtained by expanding the state observer using the Boost mode. , , All are controller gains, parameters ,parameter , and Non-smooth terms designed for Boost mode replace the traditional superspiral sign function terms, sliding surface Energy tracking error , ,in Based on reference voltage The calculated reference energy, for The derivative, sliding mode coefficient .

[0028] Furthermore, the nonlinear dynamic model of the Buck pattern is as follows:

[0029]

[0030] in, This is the low-voltage side output voltage. This refers to the inductor current in Buck mode. This is the duty cycle control input for Buck mode. For low-voltage side capacitors, For inductance, This is the nominal value of the high-voltage side load resistance. This is the nominal value of the high-voltage side input voltage. This refers to the lumped disturbance caused by input voltage changes in Buck mode. The lumped disturbance caused by changes in output load in Buck mode is defined as follows:

[0031] ,

[0032] in, This represents the actual load resistance on the high-voltage side. This is the actual input voltage on the high-voltage side.

[0033] Furthermore, the nonlinear extended state observer of the Buck pattern includes:

[0034] Used to estimate disturbances Observer:

[0035]

[0036] Used to estimate disturbances Observer:

[0037]

[0038] in, for The observed values, for The observed values, for The estimated value, for The estimated value, , , , , , , , All are adjustable gains of nonlinear extended state observers in Buck mode.

[0039] Furthermore, the controller of the Buck pattern for:

[0040]

[0041] Among them, intermediate quantity , , , All values ​​are estimates obtained by expanding the state observer using the Buck pattern, and the parameters are... ,parameter , and Non-smooth terms designed for Buck mode replace the traditional superspiral sign function terms, sliding surface Voltage tracking error , ,in, The low-voltage side reference voltage, sliding mode coefficient .

[0042] Furthermore, the construction process of the smooth switching controller for the bidirectional operating mode is as follows:

[0043] Selecting the high-voltage side voltage tracking error As a criterion, the hysteresis width is set. ;when When the system is in Boost mode, the controllable switching device is activated. The lower transistor drive; when When the condition is determined to be Buck mode, the controllable switching device is activated. The upper transistor drive; when At that time, the operating mode of the previous moment remains unchanged;

[0044] At the moment of mode switching and the subsequent transition time Internal, actual output duty cycle Calculated using a weighted transition function: ,in, The calculated value for the target mode controller. To switch the duty cycle from the previous moment, It is a weighting factor that increases linearly from 0 to 1.

[0045] A bidirectional half-bridge converter switching composite control system based on non-smooth superspiral sliding mode, comprising:

[0046] The host computer is used to write and debug the control method of this invention, and communicates with the control unit in real time through the local area network to monitor the operating status of the converter and adjust the control parameters online.

[0047] The control unit stores and executes the control method of the present invention, receives the high-voltage side voltage, low-voltage side voltage and inductor current signal of the bidirectional half-bridge converter, calculates the target duty cycle, and outputs the corresponding PWM pulse signal.

[0048] A DC power supply is connected to the input port of the bidirectional half-bridge converter to provide a stable DC input voltage for the system and is equipped with overcurrent protection.

[0049] A bidirectional half-bridge converter includes an energy storage inductor, a filter capacitor, and a power switch. It controls the power switch to turn on and off according to the PWM command output by the control unit, so as to realize the bidirectional flow of electrical energy and voltage conversion between the high-voltage side and the low-voltage side.

[0050] The signal acquisition circuit is equipped with voltage and current sensors to acquire the high-voltage side voltage, low-voltage side voltage and inductor current of the converter in real time, and feeds back the conditioned analog signal to the control unit.

[0051] The output load is connected to the output port of the bidirectional half-bridge converter to consume electrical energy, thereby simulating the load impedance characteristics under actual operating conditions or verifying the voltage regulation and control performance of the system.

[0052] The beneficial effects achieved by this invention are as follows:

[0053] (1) This invention uses hysteresis logic to determine the energy flow direction and the working mode of the converter, and uses a weighted transition function to generate the final duty cycle control signal, realizing seamless switching between Boost mode and Buck mode, and achieving high-performance control in both modes.

[0054] (2) This invention addresses the non-minimum phase problem of bidirectional DC-DC converters in Boost mode by using precise feedback linearization technology to redefine the system output as system energy and convert it into a minimum phase system, thereby simplifying controller design and ensuring system stability.

[0055] (3) The present invention introduces a nonlinear extended state observer, which can estimate the matching and unmatching disturbances caused by sudden changes in load resistance and fluctuations in input voltage in real time and accurately, realize active compensation for disturbances, and significantly enhance the robustness of the system.

[0056] (4) The present invention proposes a non-smooth super-spiral sliding mode controller. This controller uses non-smooth terms to replace the discontinuous symbol function terms in the traditional super-spiral sliding mode control. While ensuring that the tracking error converges in a finite time, it fundamentally suppresses the chattering phenomenon inherent in the traditional sliding mode control and reduces the output voltage ripple and switching stress. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the system composition of the present invention;

[0058] Figure 2 This is a topology diagram of the bidirectional half-bridge converter of the present invention;

[0059] Figure 3 This is a schematic diagram of the control structure of the present invention;

[0060] Figure 4 This is a schematic diagram of the nonlinear extended observer of the present invention;

[0061] Figure 5 This is a schematic diagram of the non-smooth superspiral sliding mode controller structure of the present invention;

[0062] Figure 6 This is a flowchart illustrating the implementation of the method of the present invention;

[0063] Figure 7(a) shows the response waveform during the startup phase of the Boost mode of the present invention;

[0064] Figure 7(b) shows the response waveform of the variable input voltage stage in the Boost mode of the present invention;

[0065] Figure 7(c) shows the response waveform of the variable load stage in the Boost mode of the present invention;

[0066] Figure 8(a) is a waveform diagram of the startup phase of the Buck mode of the present invention;

[0067] Figure 8(b) shows the response waveform of the Buck mode of the present invention in the variable input voltage stage;

[0068] Figure 8(c) is a waveform diagram of the variable load stage response of the Buck mode of the present invention;

[0069] Figure 9(a) is a duty cycle jitter diagram of the method of the present invention;

[0070] Figure 9(b) shows the duty cycle dithering diagram of the traditional method. Detailed Implementation

[0071] The following specific examples illustrate the implementation of the present invention, and those skilled in the art can easily implement it based on the content disclosed in this specification. To make the objectives, technical solutions, and effects of the present invention clearer, the technical solutions in the examples of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. It should be noted that the described embodiments are only some embodiments of the present invention, and not all embodiments. They are only used to explain the present invention and are not intended to limit the present invention.

[0072] An embodiment of a bidirectional half-bridge converter switching composite control system based on non-smooth superspiral sliding mode, its composition is as follows: Figure 1 As shown, it includes the following parts:

[0073] The host computer is used to write and debug the control method of this invention, and communicates with the control unit in real time through the local area network to monitor the operating status of the converter and adjust the control parameters online.

[0074] The control unit stores and executes the control method of the present invention through the DSP TMS320F28335, receives the high-voltage side voltage, low-voltage side voltage and inductor current signals of the bidirectional half-bridge converter, calculates the target duty cycle through the internal algorithm, and outputs the corresponding PWM pulse signal.

[0075] A DC power supply is connected to the input port (low-voltage side or high-voltage side) of the bidirectional half-bridge converter to provide a stable 0V~50V DC input voltage for the system, and is equipped with 10A overcurrent protection.

[0076] A bidirectional half-bridge converter includes an energy storage inductor, a filter capacitor, and a power switching transistor. The power switching transistor is controlled to turn on and off according to the PWM command output by the control unit, thereby realizing bidirectional flow of electrical energy and voltage conversion between the high-voltage side and the low-voltage side.

[0077] The signal acquisition circuit is equipped with voltage and current sensors to acquire the high-voltage side voltage, low-voltage side voltage and inductor current of the converter in real time, and feeds back the conditioned analog signal to the control unit.

[0078] The output load is connected to the output port of the bidirectional half-bridge converter to consume electrical energy, thereby simulating the load impedance characteristics under actual operating conditions or verifying the voltage regulation and control performance of the system.

[0079] The bidirectional half-bridge DC-DC converter topology of the present invention is as follows: Figure 2 As shown. The topology includes: a high-voltage side DC power supply (whose voltage is...) ), low-voltage side DC power supply (its voltage is ), controllable switching devices and (Typically MOSFET), Inductor High-voltage side capacitor Low-voltage side capacitor and high-voltage side load and low-voltage side load .in, and Parallel connection, then with Series connection, top tube and lower pipe After parallel connection with Series, and After parallel connection with the upper pipe Series connection. Specific circuit parameters are selected as follows: switching frequency... ,inductance High-voltage side capacitor Low-voltage side capacitor Set the nominal voltage on the low-voltage side. High voltage side nominal voltage nominal load resistance , .

[0080] like Figure 3 As shown in the schematic diagram, the control structure of the present invention includes:

[0081] The bidirectional switching module is used to determine the system's operating mode and select and switch between Boost mode and Buck mode.

[0082] Sensor module used to collect inductor current and output voltage ( or ), which serves as the system's feedback signal.

[0083] The precise feedback linearization module is used to process the acquired data. Perform a nonlinear transformation to convert the nonlinear system into a linear system, and output the linearized state variables. .

[0084] Extended state observer module, used to analyze the acquired voltage and current Real-time estimation of system input voltage and load resistance And aggregated disturbances.

[0085] The non-smooth superhelical sliding mode controller module is used to receive the estimates from the observer. , and sliding surface (From the linearized state variable error) (Calculated), and output control quantity according to sliding mode control law. .

[0086] The PWM generator module is used to receive control signals output by the controller. This generates a corresponding pulse width modulation signal to drive the power switching device.

[0087] Corresponding to the embodiments of the above system, an embodiment of a bidirectional half-bridge converter switching composite control method based on non-smooth superspiral sliding mode is as follows: Figure 6 As shown, it includes the following steps:

[0088] Step 1: The converter operates in continuous conduction mode. Based on Kirchhoff's voltage and current laws, a state-space averaging method is used for modeling. Considering the parameter perturbations (such as deviations in inductance and capacitance values) and external disturbances (such as input voltage fluctuations and load abrupt changes) that inevitably exist in the actual system, all uncertainties are uniformly summarized into a lumped disturbance term, establishing a nonlinear dynamic converter model that includes parameter uncertainties and external disturbances.

[0089] First, regarding the Boost operating mode, when energy flows from the low-pressure side to the high-pressure side ( Selecting the inductor current and high voltage side voltage For state variables, the actual dynamic equations (i.e., the converter model) are established as follows:

[0090]

[0091] in, This is the output voltage on the high-voltage side. This refers to the inductor current in Boost mode. This is the duty cycle control input for Boost mode; For high-voltage side capacitors, It is an inductor; and These are the nominal values ​​of the low-voltage side load resistance and the low-voltage side input voltage, respectively. and The lumped disturbance caused by input voltage fluctuations and output load changes in Boost mode is defined as:

[0092] ,

[0093] in, and These are the actual low-voltage side load resistance and the actual low-voltage side input voltage, respectively.

[0094] Regarding Buck operating mode, when energy flows from the high-voltage side to the low-voltage side ( Select low-voltage side voltage and inductor current For state variables, the actual dynamic equations (i.e., the converter model) are established as follows:

[0095]

[0096] in, This is the low-voltage side output voltage. This is the inductor current in Buck mode (opposite to the current direction in Boost mode). This is the duty cycle control input for Buck mode; For low-voltage side capacitors, It is an inductor; and These are the nominal values ​​of the high-voltage side load resistance and the high-voltage side input voltage, respectively. and The lumped disturbance caused by changes in input voltage and output load in Buck operating mode is defined as:

[0097] ,

[0098] in, and These represent the actual high-voltage side load resistance and the actual high-voltage side input voltage, respectively.

[0099] Step 2, in Boost mode, control the input. The presence of a negative sign in the output voltage dynamic equation results in a non-minimum phase characteristic (right-half-plane zero). To simplify controller design and ensure closed-loop stability, this step employs precise feedback linearization.

[0100] First, the system output function in Boost mode is redefined as the total energy of the system using the exact feedback linearization technique:

[0101]

[0102] Next, define the state variables. , ,in for Time derivative:

[0103]

[0104] Then, after precise feedback linearization change (i.e.) In the coordinate system, the system model of the Boost operating mode will be transformed into the following linear system to facilitate subsequent controller design:

[0105]

[0106] Among them, system function and They are defined as follows: , ; Transformed lumped disturbance and They are defined as follows: , .

[0107] Step 3, in order to achieve the above lumped disturbance To achieve real-time and accurate estimation, this invention designs nonlinear extended state observers for Boost and Buck modes respectively. Figure 4 The observer not only uses the system output error to correct the state estimate, but also expands the lumped disturbance into a new state variable for observation.

[0108] For Boost mode, an observer is designed by constructing two parallel extended state observers to estimate the perturbation. The observer is:

[0109]

[0110] Used to estimate disturbances The observer is:

[0111]

[0112] in, and They are respectively and Observed values; and They are respectively and The estimated value; , , , , , , , To enable adjustable gain of the observer, the observer bandwidth is configured. , Sure: , , , , The selection is related to practical experience. In the observer, the linear term ensures a fast response under large errors, while the nonlinear term ensures a fast convergence speed under small errors.

[0113] Similarly, design two extended state observers for the Buck pattern:

[0114]

[0115]

[0116] in, and They are respectively and Observed values; and They are respectively and The estimated value; , , , , , , , To enable adjustable gain of the observer, the observer bandwidth is configured. , Sure: , , , , The selection is related to practical experience.

[0117] Step 4: After obtaining the accurate linearized form of the model and the perturbation estimate, design controllers for both modes. This invention employs a non-smooth superspiral algorithm, which introduces non-smooth terms. Compared to traditional superspiral algorithms, it has higher convergence speed and control accuracy near the origin, and can significantly reduce chattering.

[0118] Boost Mode Controller Design: First, define the energy tracking error. , ,in and Based on reference voltage The reference energy and its derivative are calculated; then, the sliding surface of the Boost mode is defined. ,in The sliding mode coefficient; finally, the Boost mode controller Designed as follows:

[0119]

[0120] in, , , , All values ​​are estimates obtained by expanding the state observer using Boost mode. , , The controller gain is selected based on practical experience; parameters , satisfy , ; and The non-smooth term is replaced by the traditional superspiral sign function term to eliminate chattering during switching.

[0121] Buck mode controller design: First, define the voltage tracking error. , ,in The low-voltage side reference voltage is defined; next, the sliding surface of the Buck mode is defined. ,in The sliding mode coefficient; finally, the Buck mode controller Designed as follows:

[0122]

[0123] in, , , All values ​​are estimates obtained by expanding the state observer using the Buck pattern. , , The controller gain is selected based on practical experience; parameters , satisfy , ; and The non-smooth term is replaced by the traditional superspiral sign function term to eliminate chattering during switching. Figure 5 The non-smooth superspiral sliding mode controller structure designed for this invention.

[0124] Step 5, Construct a smooth switching controller for bidirectional operation mode: Select the high-voltage side voltage tracking error. As a criterion, the hysteresis width is set. (Empirical value, taken as 0.5V in this embodiment); when When the system is in Boost mode, it is activated. The lower transistor drive; when When the time is right, it is determined to be in Buck mode and activated. The upper transistor drive; when At the same time, maintain the operating mode from the previous moment; at the instant of mode switching... and the subsequent transition time Internal, actual output duty cycle Calculated using a weighted transition function:

[0125]

[0126] in, The calculated value for the target mode (Boost mode or Buck mode) controller. To switch the duty cycle from the previous moment, , The weighting factor increases linearly from 0 to 1.

[0127] An embodiment of a bidirectional half-bridge converter switching composite control method and system based on non-smooth superspiral sliding mode has been specifically explained and illustrated, making the technical solution of the present invention clearer and easier for engineers to implement. Based on this example, experiments are conducted below to further demonstrate the effectiveness of the present invention.

[0128] Based on this example, the effectiveness of the present invention will be further demonstrated through experiments.

[0129] The experimental results of this invention under three operating conditions in two different modes are presented below. First, the response of the bidirectional converter during the startup phase, i.e., the voltage response from the system's initial response to its steady-state voltage response, is tested to verify the accuracy of the control method of this invention. Second, the voltage waveform of the converter under a sudden change in input voltage is tested to verify the robustness of the control method of this invention. Third, the voltage waveform of the converter under a sudden change in load resistance is tested to verify the robustness of the control method of this invention. Fourth, a comparison of duty cycle chattering between this invention and the conventional method is presented to verify the advantages of this invention in reducing chattering.

[0130] Specifically, in the first test experiment, the converter started at 0s, performing either boost or buck voltage conversion; during the input voltage surge test, in Boost mode, At time s, the input voltage changes from 15V to 20V. At time s, the input voltage drops from 20V to 15V in Buck mode. At time s, the input voltage changes from 30V to 40V. At time s, the input voltage drops from 40V to 30V; during the load change test, in Boost mode, At time s, the output load changes from 50 Become 100 , At time s, the output load changes from 100 Reduced to 50 In Buck mode, At time s, the output load changes from 20 Become 40 , At time s, the input voltage changes from 40 Reduced to 20 .

[0131] Case 1: Voltage response waveform during the startup phase of the bidirectional converter

[0132] Boost mode: As shown in Figure 7(a), the overshoot and settling time of the method of the present invention are smaller than those of the traditional method during the startup phase.

[0133] Buck mode: As shown in Figure 8(a), the method of the present invention responds quickly during the startup phase, demonstrating the advantages of the present invention.

[0134] Case 2: Voltage response waveform of bidirectional converter when input voltage changes abruptly

[0135] Boost mode: as shown in Figure 7(b); Buck mode: as shown in Figure 8(b). When the input voltage changes abruptly, the voltage overshoot and overdrop of the method of this invention are smaller than those of the traditional method, and the voltage recovery time is shorter, demonstrating the robustness of this invention.

[0136] Case 3: Boost converter voltage response waveform when load resistance changes abruptly

[0137] Boost mode: as shown in Figure 7(c); Buck mode: as shown in Figure 8(c). When the output load changes abruptly, the voltage overshoot and overdrop of the method of this invention are smaller than those of the traditional method, and the voltage recovery time is shorter. This shows that the controller designed in this invention has a stronger ability to resist load changes.

[0138] Case 4: Duty Cycle Comparison Experiment Waveforms

[0139] Figures 9(a) and (b) show the duty cycle comparison between the present invention and the traditional method. It can be seen that the duty cycle of the present invention does not overshoot and responds quickly. Furthermore, the present invention can reduce duty cycle jitter to a certain extent, weaken the influence of traditional sliding mode sign function switching, reduce the voltage stress of the switching transistor, and improve the output voltage accuracy.

[0140] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0141] Although the present invention has been described according to various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the claims. Therefore, any obvious improvements, substitutions, or modifications that can be made by those skilled in the art without departing from the essence of the invention are within the scope of protection of the present invention.

Claims

1. A bidirectional half-bridge converter switching complex control method based on non-smooth super-spiral sliding mode, characterized in that, include: For the Boost mode and Buck mode of the bidirectional half-bridge converter, nonlinear dynamic models including parameter uncertainties and external disturbances are established respectively. By redefining the system state variables through nonlinear coordinate transformation, the converter in Boost mode is transformed into a minimum phase system, and then the nonlinear dynamic converter model in Boost mode is transformed into a linearized model. For Boost mode and Buck mode, nonlinear extended state observers are designed respectively to estimate the matched and unmatched lumped disturbances caused by input voltage fluctuations and output load changes in real time. A composite nonsmooth super-twisting sliding mode controller is designed for the boost mode based on the linearized model and the lumped disturbance estimation, and the controller for the boost mode is generated ; Based on the nonlinear dynamic model of buck mode and the lumped disturbance estimation, a composite nonsmooth hyper-spiral sliding mode controller is designed for buck mode to generate the controller of buck mode ; A smooth switching controller for bidirectional operation mode is constructed. The hysteresis width is used to determine the energy flow direction and the working mode of the converter. The final duty cycle control signal is generated through a smooth transition mechanism and applied to the bidirectional half-bridge converter to achieve seamless switching between Boost mode and Buck mode.

2. The non-smooth super-slippery sliding mode based bidirectional half-bridge converter switching complex control method according to claim 1, characterized in that, The nonlinear dynamic model of Boost mode is as follows: in, This is the output voltage on the high-voltage side. This refers to the inductor current in Boost mode. This is the duty cycle control input for Boost mode. For high-voltage side capacitors, For inductance, This is the nominal value of the low-voltage side load resistance. This is the nominal value of the low-voltage side input voltage. This refers to the lumped disturbance caused by input voltage fluctuations in Boost mode. The lumped disturbance caused by changes in output load in Boost mode is defined as follows: ， in, This represents the actual load resistance on the low-voltage side. This is the actual input voltage on the low-voltage side.

3. The bidirectional half-bridge converter switching composite control method based on non-smooth superspiral sliding mode according to claim 2, characterized in that, The system state variables are redefined as follows: The minimum phase system is: System functions and for: Transformed lumped disturbance and for: , .

4. The bidirectional half-bridge converter switching composite control method based on non-smooth superspiral sliding mode according to claim 3, characterized in that, The nonlinear extended state observer for Boost mode includes: Used to estimate disturbances Observer: Used to estimate disturbances Observer: in, for The observed values, for The observed values, for The estimated value, for The estimated value, , , , , , , , All are Boost-mode nonlinear extended state observers with adjustable gain.

5. The bidirectional half-bridge converter switching composite control method based on non-smooth superspiral sliding mode according to claim 4, characterized in that, Boost mode controller for: in, , , All values ​​are estimates obtained by expanding the state observer using the Boost mode. , , All are controller gains, parameters ,parameter , and Non-smooth terms designed for Boost mode replace the traditional superspiral sign function terms, sliding surface Energy tracking error , ,in Based on reference voltage The calculated reference energy, for The derivative, sliding mode coefficient .

6. The bidirectional half-bridge converter switching composite control method based on non-smooth superspiral sliding mode according to claim 1, characterized in that, The nonlinear dynamic model of the Buck mode is as follows: in, This is the low-voltage side output voltage. This refers to the inductor current in Buck mode. This is the duty cycle control input for Buck mode. For low-voltage side capacitors, For inductance, This is the nominal value of the high-voltage side load resistance. This is the nominal value of the high-voltage side input voltage. This refers to the lumped disturbance caused by input voltage changes in Buck mode. The lumped disturbance caused by changes in output load in Buck mode is defined as follows: ， in, This represents the actual load resistance on the high-voltage side. This is the actual input voltage on the high-voltage side.

7. The bidirectional half-bridge converter switching composite control method based on non-smooth superspiral sliding mode according to claim 6, characterized in that, The nonlinear extended state observers for Buck modes include: Used to estimate disturbances Observer: Used to estimate disturbances Observer: in, for The observed values, for The observed values, for The estimated value, for The estimated value, , , , , , , , All are adjustable gains of nonlinear extended state observers in Buck mode.

8. The bidirectional half-bridge converter switching composite control method based on non-smooth superspiral sliding mode according to claim 7, characterized in that, Buck mode controller for: Among them, intermediate quantity , , , All values ​​are estimates obtained by expanding the state observer using the Buck pattern, and the parameters are... ,parameter , and Non-smooth terms designed for Buck mode replace the traditional superspiral sign function terms, sliding surface Voltage tracking error , ,in, The low-voltage side reference voltage, sliding mode coefficient .

9. The bidirectional half-bridge converter switching composite control method based on non-smooth superspiral sliding mode according to claim 1, characterized in that, The construction process of the smooth switching controller for the bidirectional operation mode is as follows: Selecting the high-voltage side voltage tracking error As a criterion, the hysteresis width is set. ;when When the system is in Boost mode, the controllable switching device is activated. The lower transistor drive; when When the condition is determined to be Buck mode, the controllable switching device is activated. The upper transistor drive; when At that time, the operating mode of the previous moment remains unchanged; At the moment of mode switching and the subsequent transition time Internal, actual output duty cycle Calculated using a weighted transition function: ,in, The calculated value for the target mode controller. To switch the duty cycle from the previous moment, It is a weighting factor that increases linearly from 0 to 1.

10. A system for implementing the bidirectional half-bridge converter switching composite control method based on non-smooth superspiral sliding mode as described in any one of claims 1-9, characterized in that, include: The host computer is used to write and debug the control method of this invention, and communicates with the control unit in real time through the local area network to monitor the operating status of the converter and adjust the control parameters online. The control unit stores and executes the control method of the present invention, receives the high-voltage side voltage, low-voltage side voltage and inductor current signal of the bidirectional half-bridge converter, calculates the target duty cycle, and outputs the corresponding PWM pulse signal. A DC power supply is connected to the input port of the bidirectional half-bridge converter to provide a stable DC input voltage for the system and is equipped with overcurrent protection. A bidirectional half-bridge converter includes an energy storage inductor, a filter capacitor, and a power switch. It controls the power switch to turn on and off according to the PWM command output by the control unit, so as to realize the bidirectional flow of electrical energy and voltage conversion between the high-voltage side and the low-voltage side. The signal acquisition circuit is equipped with voltage and current sensors to acquire the high-voltage side voltage, low-voltage side voltage and inductor current of the converter in real time, and feeds back the conditioned analog signal to the control unit. The output load is connected to the output port of the bidirectional half-bridge converter to consume electrical energy, thereby simulating the load impedance characteristics under actual operating conditions or verifying the voltage regulation and control performance of the system.

Images