Nonlinear suppression method and system for multiple power approaching law sliding mode control voltage doubling quasi-z-source inverter

Abstract

The application discloses a nonlinear suppression method and system of a multiple power approaching law sliding mode control voltage-doubler quasi-Z-source inverter, and belongs to the technical field of power electronic converter control, which comprises the following steps: establishing a discrete iterative model of a voltage-doubler quasi-Z-source inverter; designing a sliding mode controller based on a multiple power approaching law, wherein the multiple power approaching law adaptively adjusts multiple power terms according to the distance between the system state and the sliding mode surface, realizes the balance between fast approaching and gentle approaching, and suppresses chattering; verifying the stability of the sliding mode controller by using Lyapunov stability theory, introducing a fast variable stability theorem, determining the two-dimensional stable domain of the sliding mode control parameters by judging the sum of the sign functions of the duty cycle difference of the continuous switching period, and the sliding mode control strategy has excellent robustness when the input voltage fluctuates widely, can effectively suppress bifurcation and chaos, and improves the output power quality. The application is suitable for photovoltaic grid-connected applications with large input voltage fluctuations.

Description

Technical Field

[0001] This invention relates to a nonlinearity suppression method for a multi-power-law approaching sliding mode control voltage multiplier quasi-Z source inverter, belonging to the field of power electronic converter control technology. Background Technology

[0002] In grid-connected photovoltaic power generation systems, quasi-Z-source inverters (q-ZSIs) with high step-up ratios are often used to match the bus voltage. However, the numerous switching operations within a q-ZSI make it a highly nonlinear system, prone to inducing complex dynamic behaviors such as bifurcation and chaos under actual operating conditions, thereby degrading the output power quality and even jeopardizing the stable operation of the system. Currently, research on q-ZSIs mainly focuses on topology improvement, performance optimization, and engineering applications, while the exploration of the nonlinear behavior mechanisms during its operation remains insufficient.

[0003] Sliding mode control, as a typical nonlinear control strategy, has attracted widespread attention in power converters such as H-bridge inverters due to its fast dynamic response and insensitivity to parameter perturbations and external disturbances. Previous studies have introduced power-law and improved exponential-law approaching techniques into the design of sliding mode controllers for H-bridge inverters, exploring various nonlinear phenomena induced by changes in control parameters. However, the inherent chattering problem in sliding mode control can affect equipment performance. Research shows that multi-power-law approaching techniques can effectively improve the dynamic quality of sliding mode motion, suppress chattering, and ensure that the system state converges quickly to the equilibrium neighborhood.

[0004] Currently, research on the nonlinear dynamic behavior of voltage multiplier unit quasi-Z source inverter (VMC-qZSI) systems is insufficient, particularly regarding the suppression mechanism of bifurcation and chaos phenomena and the analysis of parameter stability domains using sliding mode control based on reaching laws. Therefore, it is necessary to propose a control method that can effectively suppress bifurcation and chaos phenomena during VMC-qZSI operation and provide the stability domains of the control parameters to improve the system's robustness and output power quality. Summary of the Invention

[0005] Based on the problems described in the background, the problem to be solved by the present invention is to provide a nonlinear suppression method and system for a multi-power-approaching law sliding mode control voltage multiplier quasi-Z source inverter. By establishing an accurate discrete iterative model of the system, designing a sliding mode controller based on a multi-power-approaching law, and using the fast-variable stability theorem to determine the two-dimensional stability domain of the control parameters, the bifurcation and chaos phenomena are effectively suppressed, and the robustness of the system to input voltage fluctuations is enhanced.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for nonlinear suppression of a multi-power-law approaching law sliding mode control voltage multiplier quasi-Z source inverter, comprising the following steps:

[0007] S1. Establish a discrete iterative model for the voltage multiplier unit quasi-Z source inverter. The discrete iterative model is obtained by integrating the state transition matrix based on the state equations of the inverter in non-shot-through operating mode I, non-shot-through operating mode II, and shot-through operating mode III in one switching cycle.

[0008] S2. Design a sliding mode controller based on a multi-power approach law, wherein the sliding surface function is defined as the deviation between the sampled value of the output inductor current and the reference current. The multi-power approach law includes multiple power terms that are adaptively adjusted according to the distance of the system state from the sliding surface, so as to achieve rapid approach when far from the sliding surface and smooth approach when close to the sliding surface, thereby suppressing chattering.

[0009] Preferably, the expression for the power-law approach is: In the formula, λ1, λ2, λ3, λ4>0, α>1, 0<β<1, and γ is a parameter for adjusting the reaching law characteristics and is adaptively adjusted according to the system state.

[0010] Preferably, the sliding surface function is defined as: In the formula: i Lf (n) represents the sampled value of the inductor current in the nth cycle; i ref (n) is the reference current in the nth cycle, i ref (n)=I m sin(ωt), ω=2πf, f=50Hz; g1, g2≠0.

[0011] Preferred options also include:

[0012] S3. Verify the stability of the sliding mode controller using Lyapunov stability theory, and determine the two-dimensional stability domain of the sliding mode control parameters using the fast-variable stability theorem; the fast-variable stability theorem determines the system stability by calculating the sum of the sign functions of the duty cycle differences of continuous switching cycles.

[0013] The specific formula is as follows: If |P|=H is satisfied, the system is considered stable; otherwise, it is unstable.

[0014] Preferably, in the discrete iterative model, the integral formula for the state transition matrix within one switching period T is:

[0015]

[0016] In the formula, t1=d n T - DT / 2, t2 = (1 - d) n )T-DT / 2, t3=DT, I is the second-order identity matrix, D is the through duty cycle, d nLet A1, A2, and A3 be the duty cycle of the nth cycle, and let B1, B2, and B3 be the system matrices for the three operating modes, respectively. Let B1, B2, and B3 be the corresponding input matrices.

[0017] This invention also provides a nonlinear suppression system for a multi-power-law approaching law sliding mode controlled voltage multiplier quasi-Z source inverter, comprising:

[0018] The model building module is used to build a discrete iterative model of the voltage multiplier unit quasi-Z source inverter.

[0019] The sliding mode controller design module is used to design a sliding mode controller based on a multi-power-law approach and solve the duty cycle calculation formula.

[0020] The stability analysis module is used to verify the stability of the sliding mode controller using Lyapunov stability theory and to determine the two-dimensional stability domain of the sliding mode control parameters using the fast change stability theorem.

[0021] The control execution module is used to apply the designed sliding mode controller to the voltage multiplier unit quasi-Z source inverter. It generates drive signals according to the duty cycle calculation formula, controls the switching of the inverter switching transistors, and suppresses bifurcation and chaos phenomena.

[0022] Preferably, in the sliding mode controller design module, the expression for the multi-power reaching law, the definition of the sliding surface function, and the formula for calculating the duty cycle are shown below:

[0023] The expression for the power-law of convergence is: In the formula, λ1, λ2, λ3, λ4>0, α>1, 0<β<1, and γ is a parameter for adjusting the reaching law characteristics and is adaptively adjusted according to the system state;

[0024] The sliding surface function is defined as: In the formula: i Lf (n) represents the sampled value of the inductor current in the nth cycle; i ref (n) is the reference current in the nth cycle, i ref (n)=I m sin(ωt), ω=2πf, f=50Hz; g1, g2≠0;

[0025] The formula for calculating duty cycle: , .

[0026] The present invention also proposes an electronic device, including a memory and a processor, and computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the steps described in a nonlinear suppression method for a multi-power-law sliding mode control voltage doubler quasi-Z source inverter.

[0027] The present invention also proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, complete the steps described in a method for nonlinear suppression of a multi-power-law sliding mode control voltage doubler quasi-Z-source inverter.

[0028] The beneficial effects of this invention are:

[0029] 1. This invention establishes an accurate discrete iterative model of the voltage multiplier unit quasi-Z source inverter, and combines bifurcation diagrams, phase trajectory diagrams and spectrum diagrams to reveal the complex nonlinear evolution path (stable-chaotic-periodic-chaotic) of the system under the disturbance of control parameters and circuit parameters, providing a theoretical basis for the selection of control parameters.

[0030] 2. This invention designs a sliding mode controller based on a multi-power approach law. This approach law can adaptively adjust the dominant term according to the distance of the system state from the sliding surface, achieving rapid approach when far from the sliding surface and smooth approach when close to the sliding surface, effectively suppressing the chattering problem of traditional sliding mode control.

[0031] 3. This invention introduces the fast-variable stability theorem, and quantitatively determines the two-dimensional stability domain of the sliding mode control parameters by calculating the sum of the sign functions of the duty cycle differences of continuous switching cycles. This overcomes the difficulty of directly applying the Jacobian matrix method for stability analysis because the sliding mode control law contains sign functions.

[0032] 4. Compared with traditional proportional control, the sliding mode control strategy proposed in this invention exhibits excellent robustness when the input voltage fluctuates widely (e.g., in photovoltaic power generation scenarios). The inductor current sampling points are always closely distributed near the peak value of the reference current, without any bifurcation or chaotic signs, which significantly improves the output power quality and operational reliability of the system. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the current control type of the voltage multiplier unit quasi-Z source inverter in an embodiment of the present invention;

[0034] Figure 2 The diagram shows three operating modes of the voltage multiplier unit quasi-Z source inverter in this embodiment of the invention; where (a) is non-direct-through operation mode I, (b) is non-direct-through operation mode II, and (c) is direct-through operation mode III.

[0035] Figure 3 This is a schematic diagram of the sawtooth carrier modulation strategy in an embodiment of the present invention;

[0036] Figure 4 This is the equivalent circuit diagram of the AC side of the voltage multiplier unit quasi-Z source inverter in an embodiment of the present invention;

[0037] Figure 5This is a block diagram of a sliding mode controller system based on a multi-power-order reaching law in an embodiment of the present invention;

[0038] Figure 6 The diagram shows the inductor current bifurcation diagram of parameter g1 under sliding mode control in this embodiment of the invention; where (a) is the bifurcation diagram at the peak value and (b) is the bifurcation diagram at the valley value.

[0039] Figure 7 The phase path diagrams and spectrum diagrams under different bifurcation parameters g1 in the embodiments of the present invention are shown; where (a) corresponds to g1=2000, (b) corresponds to g1=3000, and (c) corresponds to g1=6000.

[0040] Figure 8 The diagram shows the inductor current bifurcation diagram of parameter g2 under sliding mode control in this embodiment of the invention; where (a) is the bifurcation diagram at the peak value and (b) is the bifurcation diagram at the valley value.

[0041] Figure 9 The diagrams shown are the phase path diagrams and spectrum diagrams under different bifurcation parameters g2 in the embodiments of the present invention; where (a) corresponds to g2=5, (b) corresponds to g2=18, and (c) corresponds to g2=22.

[0042] Figure 10 This is a bifurcation diagram showing the change of inductor current with input voltage in an embodiment of the present invention; where (a) is under proportional control and (b) is under sliding mode control.

[0043] Figure 11 This is a bifurcation diagram showing the variation of inductor current with circuit parameters in an embodiment of the present invention; where (a) is the filter inductor L. f (b) is the parameter bifurcation diagram of the load resistance R parameter;

[0044] Figure 12 This is a two-dimensional stability domain diagram of control parameters g1-g2 in an embodiment of the present invention;

[0045] Figure 13 These are the time-domain plot and enlarged view of the time-domain plot when the sliding mode parameter g2=5 in this embodiment of the invention;

[0046] Figure 14 The images show the time-domain plot and an enlarged view of the time-domain plot when the sliding mode parameter g2 = 11.5 in this embodiment of the invention.

[0047] Figure 15 The images show the time-domain plot and an enlarged view of the time-domain plot when the sliding mode parameter g2=22 in an embodiment of the present invention. Detailed Implementation

[0048] The embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0049] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0050] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0051] Example 1

[0052] In this embodiment, a method for establishing a discrete iterative model of a voltage multiplier unit quasi-Z source inverter (VMC-qZSI) is disclosed, including:

[0053] A discrete iterative model of a voltage multiplier unit quasi-Z source inverter (VMC-qZSI) is established. The discrete iterative model is obtained by integrating the state transition matrix based on the state equations of the inverter in non-shoo-through operating mode I, non-shoo-through operating mode II, and shoot-through operating mode III in one switching cycle.

[0054] like Figure 1 As shown, the VMC-qZSI main circuit topology used in this embodiment consists of an improved quasi-Z-source network with integrated voltage multiplier units cascaded with an H-bridge inverter with LC filtering. The output voltage of the front-end photovoltaic array is fed into the VMC-qZSI system after passing through a voltage stabilizing capacitor. The core of the boost stage lies in two symmetrical voltage multiplier units, which share the secondary side of the coupling winding. Each unit consists of a capacitor, a diode, and the secondary winding of the coupling winding. The back-end H-bridge inverter consists of four power switches, responsible for converting DC to AC. The system adopts a dual-loop control strategy: the front stage generates a PWM drive signal through the maximum power point tracking (MPPT) algorithm; the back stage samples the filtered inductor current, compares it with a given reference current, sends the error signal to the sliding mode controller, calculates the required duty cycle in real time, and generates an SPWM wave to drive the back-end switches.

[0055] VMC-qZSI contains three operating modes within one switching cycle, such as Figure 2 As shown. The non-straight-through state can be further subdivided into Mode I and Mode II, as follows: Figure 2 As shown in (a) and 2(b); the through state corresponds to mode III, as follows Figure 2 As shown in (c).

[0056] This embodiment uses a sawtooth wave as the modulation carrier, and its control logic for the switching transistor is as follows: Figure 3 As shown. During one switching cycle, when the instantaneous value of the sawtooth wave is greater than the duty cycle signal, the system enters the shoot-through mode, at which time all four switches are turned on simultaneously; the rest of the time the system operates in the non-shoot-through mode.

[0057] Based on the three operating modes, write the state equations describing the system dynamics in both the non-shot-through and shot-through modes within one switching cycle T:

[0058] Non-pass-through working mode I:

[0059] (1)

[0060] Non-straight-through working mode II:

[0061] (2)

[0062] Straight-through working mode III:

[0063] (3)

[0064] In the formula, i Lf For the output inductor current, v Cf For the output capacitor voltage, L f For the filter inductor, C f Here, R is the filter capacitor, and V is the load resistance. PN Let i be the DC-side equivalent voltage. Assume the output inductor current is i. Lf and output capacitor voltage v Cf As state variables, the system state equations can be simplified to the form of a linear time-invariant system:

[0065] (4)

[0066] In the formula, , , , , , .

[0067] When A i When (i=1,2,3) is invertible, the state changes of the system in different time periods can be calculated by integrating the state transition matrix. The solution to this state equation is:

[0068] (5)

[0069] In the formula, t1=d n T - DT / 2, t2 = (1 - d) n)T-DT / 2, t3=DT, I is a second-order identity matrix.

[0070] Example 2

[0071] In this embodiment, a design method for a sliding mode controller based on a multi-power-law approach is disclosed. The sliding surface function is defined as the deviation between the sampled output inductor current and the reference current. The multi-power-law approach includes multiple power terms adaptively adjusted according to the system state's distance from the sliding surface, to achieve rapid approach when far from the sliding surface and gradual approach when close to the sliding surface, thereby suppressing chattering. The method includes:

[0072] For ease of controller design, the boost side is equivalent to a DC voltage source v. PN The equivalent circuit of the VMC-QZSI AC side is obtained, such as... Figure 4 As shown, a discrete iterative model of the system is established based on this.

[0073] (6)

[0074] In the formula, the sign of u represents the switching state of the inverter. When u = -1, the system is in non-shoot-through mode I, corresponding to the conduction of switches S1 and S3; when u = 1, the system is in non-shoot-through mode II, corresponding to the conduction of switches S2 and S4. The signal for the shoot-through state is achieved by performing a logical OR operation between the shoot-through duty cycle signal and the switching state signal.

[0075] Define the sliding surface function as follows:

[0076] (7)

[0077] In the formula: i Lf (n) represents the sampled value of the inductor current in the nth cycle; i ref (n) is the reference current in the nth cycle, i ref (n)=I m sin(ωt), ω=2πf, f=50Hz; g1, g2≠0.

[0078] make (8)

[0079] Differentiating with respect to the sliding surface yields

[0080] (9)

[0081] Substituting equation (6) into equation (9), we get

[0082] (10)

[0083] To improve the dynamic quality of sliding mode motion and suppress chattering, this paper introduces a multi-power reaching law, the expression of which is as follows:

[0084] (11)

[0085] In the formula, λ1, λ2, λ3, λ4 > 0, α > 1, 0 < β < 1, and γ is a parameter for adjusting the reaching law characteristic. The parameters are adaptively adjusted according to the system state.

[0086] (12)

[0087] The advantage of the power-law approach is that:

[0088] (1) When the system state is far from the sliding surface and |s|≥1, -λ1|s| α sgn(s)-λ3|s| γ The term sgn(s) dominates the convergence process, achieving rapid convergence through dynamic adjustment;

[0089] (2) When the system state is close to the sliding surface |s|<1, -λ1|s| β sgn(s)-λ3|s| γ The sgn(s) term plays a major role, ensuring a smooth approach through dynamic adjustment, thereby effectively reducing chattering.

[0090] To ensure that the system state reaches the sliding surface under any initial conditions, the stability of the control law needs to be verified. The Lyapunov function is selected as shown in equation (13):

[0091] (13)

[0092] Differentiating the above equation, we get:

[0093] (14)

[0094] According to Lyapunov stability theory, a system must satisfy the following conditions to be stable: The condition holds true for all cases. From equations (9) and (12), we can obtain:

[0095] (15)

[0096] From the above equation, we can see that when λ1, λ2, λ3, λ4 > 0, The conditions are always met, thus ensuring the accessibility and stability of the sliding motion.

[0097] Solving equations (6), (9), and (11) simultaneously yields the equivalent control quantity, i.e., the duty cycle. The calculation formula is:

[0098] (16)

[0099] The final duty cycle formula is as follows:

[0100] (17)

[0101] The VMC-qZSI discrete iterative model established in this embodiment is composed of the aforementioned state transition matrix integral equation and duty cycle calculation formula. The system block diagram of the sliding mode controller based on the multi-power-law reaching law is shown below. Figure 5 As shown.

[0102] Example 3

[0103] In this embodiment, a method for determining the two-dimensional stability domain of sliding mode control parameters using the rapid change stability theorem is disclosed, including:

[0104] Since the sliding mode control law contains a sign function sgn, it is difficult to directly apply the Jacobian matrix method for stability analysis. Therefore, this embodiment introduces the fast-variable stability theorem to solve for the stability region of the control parameters. The basic idea of ​​this theorem is: select H consecutive switching cycles within the rising or falling segment of the output current, calculate the sum of the sign functions of the difference between the duty cycle of each cycle and the duty cycle of the next cycle, and define this sum as P. If |P|=H, the system is considered stable; otherwise, it is unstable.

[0105] (18)

[0106] In this embodiment, sampling points H0=464 and H=36 are selected for the rising segment. Based on this theorem, g1∈[600,2200] and g2∈[10,25] are chosen, and the two-dimensional stability region of g1-g2 is plotted as follows: Figure 12 As shown. By Figure 12 It can be seen that the two-dimensional stability region is large, indicating that the designed sliding mode control is robust and the system stability is not easily affected by the control parameters. Furthermore, the smaller the control parameters g1 and g2 are, the better the system stability.

[0107] Example 4

[0108] In this embodiment, a method for analyzing and verifying the nonlinear dynamic behavior of the designed sliding mode control system is disclosed, including:

[0109] Table 1

[0110] <![CDATA[V g / V]]> T / μs <![CDATA[I m / A]]> <![CDATA[C(C1=C2=C) / μF]]> <![CDATA[L N1 / μH]]> <![CDATA[L N2 / μH]]> <![CDATA[L f / mH]]> <![CDATA[C f / μF]]> R / Ω D 30 50 2 330 927 42 5 47 10 0.1

[0111] This embodiment uses the system simulation parameters shown in Table 1. The parameters of the multi-power reaching law are set as λ1=1.3, λ2=0.5, λ3=1.5, λ4=0.1, α=2.4, and β=0.6. By drawing bifurcation diagrams, phase path diagrams, and spectrum diagrams, the dynamic evolution path of the system under different control parameters is intuitively displayed.

[0112] Using the parameters of the sliding mode controller g1 as variables, plot the bifurcation diagram of the inductor current at the peak and valley sampling points, as shown below. Figure 6 As shown in the diagram, the dynamic behavior of the system exhibits a complex evolutionary path as g1 increases: when 0 ≤ g1 < 2200, the system operates in a stable period 1 state; when 2200 ≤ g1 < 2780, the system is in a chaotic state; when 2780 ≤ g1 < 3400, a period 6 window appears; when 3400 ≤ g1 < 4800, a period 7 window appears; and when 4800 ≤ g1 < 6000, the system re-enters a chaotic state. From the bifurcation diagram, as the g1 parameter increases, an alternating evolutionary path of "stable-chaotic-periodic-chaotic" emerges.

[0113] Select the g1 parameter points corresponding to the stable region, bifurcation region, and chaotic region respectively, and draw their corresponding phase trajectory diagrams and spectrum diagrams, as follows: Figure 7 As shown. When g1=2000, the system is stable, the phase trajectory is a smooth closed curve, and the spectrum contains only the fundamental frequency and the switching frequency and its sidebands; when g1=3000, the system is in a bifurcation state, the phase trajectory shows multiple stripes, and the spectrum shows obvious fractional frequency components; when g1=6000, the system enters a chaotic state, the phase trajectory becomes a "chaotic band" that fills the phase space, and the background noise in the spectrum is significantly increased.

[0114] Similarly, using the controller parameter g2 as the bifurcation parameter for analysis, the resulting bifurcation diagram is as follows: Figure 8 As shown, the phase trajectory diagrams and spectrum diagrams under different g2 values ​​are as follows: Figure 9 As shown in the figure. The experimental results are consistent with the theoretical analysis.

[0115] Considering the wide fluctuation characteristics of input voltage in photovoltaic power generation, this embodiment compares and analyzes the dynamic behavior of the system with input voltage as the bifurcation parameter under traditional proportional control and the proposed sliding mode control. The results are as follows: Figure 10 As shown, under proportional control, when the input voltage exceeds 104V, the system experiences period-doubling bifurcation, resulting in distortion of the current waveform. However, under the sliding mode control designed in this embodiment, even when the input voltage rises from 40V to 350V, the sampling points of the inductor current remain closely distributed near the peak value of the reference current, without any signs of bifurcation or chaos. This demonstrates that the proposed sliding mode control strategy has strong robustness to input voltage disturbances.

[0116] Furthermore, the system behavior when the filter inductance and load resistance are used as bifurcation parameters is as follows: Figure 11 As shown in the figure. Analysis indicates that, to ensure stable system operation, the value of the filter inductor should not be too small, and the value of the load resistance should not be too large.

[0117] Example 5

[0118] In this embodiment, the experimental results of a voltage multiplier quasi-Z-source inverter based on multi-power-law sliding mode control are disclosed. The correctness of the conclusions of Embodiment 4 is verified through hardware-in-the-loop simulation, including:

[0119] Based on theoretical analysis and simulation calculations, this embodiment constructs a hardware-in-the-loop simulation platform based on dSPACE for experimental verification. The experimental prototype and simulation platform are as follows: Figure 13 As shown in Table 1, the operating parameters are configured with a fixed control parameter g1=2000, and g2=5, 11.5, and 22 respectively. The experimental waveforms are shown in the figure. Figures 13-15 As shown.

[0120] When g2=5 ( Figure 13 The output inductor current waveform is stable and smooth, and the system is in a stable period 1 state; when g2=11.5 ( Figure 14 The output inductor current waveform is significantly distorted, fluctuates irregularly, and the system is in a chaotic state; when g2=22 ( Figure 15 The amplitude of the output inductor current waveform change intensifies, the harmonic distortion rate continues to increase, and the system is in a chaotic state. Experimental results and... Figure 8 , Figure 9 The results are consistent with the theoretical analysis, verifying the effectiveness of the established model and theoretical analysis.

[0121] This invention also provides a nonlinear suppression system for a multi-power-law approaching law sliding mode control voltage multiplier quasi-Z source inverter, comprising:

[0122] The model building module is used to build a discrete iterative model of the voltage multiplier unit quasi-Z source inverter.

[0123] The sliding mode controller design module is used to design a sliding mode controller based on a multi-power-law approach and solve the duty cycle calculation formula.

[0124] The stability analysis module is used to verify the stability of the sliding mode controller using Lyapunov stability theory and to determine the two-dimensional stability domain of the sliding mode control parameters using the fast change stability theorem.

[0125] The control execution module is used to apply the designed sliding mode controller to the voltage multiplier unit quasi-Z source inverter. It generates drive signals according to the duty cycle calculation formula, controls the switching of the inverter switching transistors, and suppresses bifurcation and chaos phenomena.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A nonlinearity suppression method for a multi-power-law approaching sliding mode control voltage multiplier quasi-Z-source inverter, characterized in that, Includes the following steps: S1. Establish a discrete iterative model for the voltage multiplier unit quasi-Z source inverter. The discrete iterative model is obtained by integrating the state transition matrix based on the state equations of the inverter in non-shot-through operating mode I, non-shot-through operating mode II, and shot-through operating mode III in one switching cycle. S2. Design a sliding mode controller based on a multi-power approach law, wherein the sliding surface function is defined as the deviation between the sampled value of the output inductor current and the reference current. The multi-power approach law includes multiple power terms that are adaptively adjusted according to the distance of the system state from the sliding surface, so as to achieve rapid approach when far from the sliding surface and smooth approach when close to the sliding surface, thereby suppressing chattering.

2. The nonlinearity suppression method for a multi-power-law approaching law sliding mode control voltage multiplier quasi-Z-source inverter according to claim 1, characterized in that, The expression for the power-law approach is: In the formula, λ1, λ2, λ3, λ4>0, α>1, 0<β<1, and γ is a parameter for adjusting the reaching law characteristics and is adaptively adjusted according to the system state.

3. The nonlinearity suppression method for a multi-power-law approaching sliding mode control voltage multiplier quasi-Z-source inverter according to claim 1, characterized in that, The sliding surface function is defined as follows: In the formula: i Lf (n) represents the sampled value of the inductor current in the nth cycle; i ref (n) is the reference current in the nth cycle, i ref (n)=I m sin(ωt), ω=2πf, f=50Hz; g1, g2≠0.

4. The nonlinear suppression method for a multi-power-law approaching sliding mode control voltage multiplier quasi-Z-source inverter according to claim 1, characterized in that, Also includes: S3. Verify the stability of the sliding mode controller using Lyapunov stability theory, and determine the two-dimensional stability domain of the sliding mode control parameters using the fast-variable stability theorem; the fast-variable stability theorem determines the system stability by calculating the sum of the sign functions of the duty cycle differences of continuous switching cycles. The specific formula is as follows: If |P|=H is satisfied, the system is considered stable; otherwise, it is unstable.

5. The nonlinearity suppression method for a multi-power-law approaching sliding mode control voltage multiplier quasi-Z-source inverter according to claim 1, characterized in that, In the discrete iterative model, the integral formula for the state transition matrix within one switching period T is: In the formula, t1=d n T - DT / 2, t2 = (1 - d) n )T-DT / 2, t3=DT, I is the second-order identity matrix, D is the through duty cycle, d n Let A1, A2, and A3 be the duty cycle of the nth cycle, and let B1, B2, and B3 be the system matrices for the three operating modes, respectively. Let B1, B2, and B3 be the corresponding input matrices.

6. A nonlinear suppression system for a multi-power-law approaching sliding mode controlled voltage multiplier quasi-Z-source inverter, characterized in that, include: The model building module is used to build a discrete iterative model of the voltage multiplier unit quasi-Z source inverter. The sliding mode controller design module is used to design a sliding mode controller based on a multi-power-law approach and solve the duty cycle calculation formula. The stability analysis module is used to verify the stability of the sliding mode controller using Lyapunov stability theory and to determine the two-dimensional stability domain of the sliding mode control parameters using the fast change stability theorem. The control execution module is used to apply the designed sliding mode controller to the voltage multiplier unit quasi-Z source inverter. It generates drive signals according to the duty cycle calculation formula, controls the switching of the inverter switching transistors, and suppresses bifurcation and chaos phenomena.

7. The nonlinear suppression system for a multi-power-law approaching law sliding mode control voltage multiplier quasi-Z-source inverter according to claim 6, characterized in that, In the sliding mode controller design module, the expression for the multi-power reaching law, the definition of the sliding surface function, and the formula for calculating the duty cycle are shown below: The expression for the power-law of convergence is: In the formula, λ1, λ2, λ3, λ4>0, α>1, 0<β<1, and γ is a parameter for adjusting the reaching law characteristics and is adaptively adjusted according to the system state; The sliding surface function is defined as: In the formula: i Lf (n) represents the sampled value of the inductor current in the nth cycle; i ref (n) is the reference current in the nth cycle, i ref (n)=I m sin(ωt), ω=2πf, f=50Hz; g1, g2≠0; The formula for calculating duty cycle: , .

8. An electronic device comprising a memory and a processor, and computer instructions stored in the memory and running on the processor, characterized in that, When the computer instructions are executed by the processor, they complete the steps of the nonlinear suppression method for a multi-power approach law sliding mode control voltage multiplier quasi-Z source inverter as described in any one of claims 1 to 5.

9. A computer-readable storage medium for storing computer instructions, characterized in that, When the computer instructions are executed by the processor, they complete the steps of the nonlinear suppression method for a multi-power approach law sliding mode control voltage multiplier quasi-Z source inverter as described in any one of claims 1 to 5.

Images