NLADRC voltage control method of efficient power converter for electric vehicle

Abstract

The invention discloses an NLADRC voltage control method of a high-efficiency power converter for an electric vehicle, and relates to the technical field of NLADRC voltage control of the high-efficiency power converter for the electric vehicle, and the method comprises the steps: building a CLLLC resonant converter equivalent model based on a fundamental wave analysis method; solving a voltage gain by adopting a linear circuit solving method through an FHA equivalent model of the CLLLC resonant converter; and an improved anti-integral saturation NLADRC voltage control strategy is established. According to the method disclosed by the invention, the anti-interference capability and the stability are remarkably improved by applying an improved anti-integral saturation nonlinear active-disturbance-rejection control strategy. By using a nonlinear filtering function, the strategy effectively suppresses fluctuation in response, accelerates the stabilization speed, and improves the stability and robustness of overall control.

Description

Technical Field

[0001] The invention relates to the technical field of electric vehicles, and in particular to a NLADRC voltage control method of a high-efficiency power converter for electric vehicles. Background Art

[0002] With the booming development of the electric vehicle industry, on-board chargers, as core components of electric vehicles, are mainly focused on high-frequency, high-efficiency, high-power density and high-performance control technologies. Gallium nitride high electron mobility transistors (GaN High Electron Mobility Transistor, GaN HEMT) have the characteristics of fast switching speed and low loss, which is conducive to improving the switching frequency and overall efficiency of on-board chargers, but it also brings challenges in circuit topology and control technology. Therefore, this paper conducts an in-depth study on the control method of a two-stage bidirectional on-board charger based on GaN HEMT.

[0003] First of all, the on-board charger must meet the requirements of power quality, that is, it must have functions such as improving power factor and reducing current THD to reduce harmonic pollution to the power grid; secondly, it needs to have a larger output voltage range to meet the charging needs of the battery. Since GaN HEMT can effectively suppress reverse recovery, the totem pole bridgeless PFC has been widely used and has become a hot spot in high-frequency PFC topology research. The back stage of the on-board charger mainly provides safe and reliable wide-range voltage output. At present, CLLLC resonant converters are mainly used. The existing technology studies the synchronous rectification of the CLLLC resonant converter to further reduce the conduction loss caused by the body diode.

[0004] Aiming at the problem of poor anti-interference ability of CLLLC resonant converter, a nonlinear self-interference rejection voltage control strategy based on improved anti-integral saturation is proposed. The system stability and robustness are effectively improved by improving the anti-integral saturation design and nonlinear filter function. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above problems or problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the technical problem solved by the present invention is that the CLLLC resonant converter has poor anti-interference capability.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a NLADRC voltage control method for a high-efficiency power converter for electric vehicles, which includes establishing a CLLLC resonant converter equivalent model based on a fundamental wave analysis method;

[0009] The voltage gain is solved by using the FHA equivalent model of the CLLLC resonant converter and the linear circuit solution method.

[0010] An improved anti-integral saturation NLADRC voltage control strategy is established.

[0011] As a preferred solution of the NLADRC voltage control method of the high-efficiency power converter for electric vehicles of the present invention, wherein: the CLLLC resonant converter equivalent model established based on the fundamental wave analysis method includes:

[0012] The full-bridge equivalent replacement of the CLLLC resonant converter is performed, and the secondary side of the transformer is converted to the primary side to obtain the FHA model of the CLLLC resonant converter; where V AB_FHA It is the sine wave voltage equivalent to the voltage between the midpoints of the inverter bridge arm through FHA; L r1 and C r1 are the resonant inductance and capacitance of the primary and primary sides respectively; let n p is the transformer ratio, the resonant inductance of the secondary side converted to the primary side Resonant capacitor Req is the load obtained by using FHA to equalize the resistive load on the output side;

[0013] Due to the switching of the switching devices in the inverter unit, the voltage between the midpoints of the bridge arms is actually V in and -V in The square wave voltage that jumps between is shown as follows:

[0014]

[0015] Among them, T s is the switching period, i.e. T s =1 / f s , where f s is the switching cycle;

[0016] Performing Fourier transform on the above equation gives the following equation:

[0017]

[0018] Where n is the integer parameter of the Fourier series expansion;

[0019] In the fundamental wave analysis method, it is believed that the energy of the input signal mainly comes from the fundamental wave component, and the remaining high-order harmonics are negligible; the fundamental wave component and its effective value are extracted as follows:

[0020]

[0021] Since the input of CLLLC needs to pass through the inverter unit, the current flowing through the resonant cavity is actually an alternating current. According to the idea of ​​fundamental wave analysis, it is equivalent to a sine wave as follows:

[0022]

[0023] I r1 is the transformer primary resonant current i r1 (t) effective value, Yes V AB_FHA (t) and i r1 (t) The phase difference between them, similarly, the fundamental component and effective value of the voltage between the midpoints CD of the two bridge arms of the rectifier unit are obtained:

[0024]

[0025] Where θ is the phase difference between the output side and the input side;

[0026] The current in the secondary resonant cavity is expressed as:

[0027]

[0028] Among them, I r2 is the effective value of the transformer secondary resonant current ir2(t);

[0029] The resonant cavity obtains the output current through the rectifier unit, so the output average current is:

[0030]

[0031] Among them, I o is the output current, P o is the output power, V o is the output voltage, R o is the output resistive load;

[0032] From the above formula, we can see that V CD_FHA (t) and i r2 (t) are in phase, so Ro is equivalent to the equivalent output resistance Req of the FHA model:

[0033]

[0034] As a preferred solution of the NLADRC voltage control method of the high-efficiency power converter for electric vehicles of the present invention, wherein: the FHA equivalent model based on the CLLLC resonant converter, through the linear circuit solving method, solves the voltage gain including:

[0035] The voltage gain of the CLLLC resonant converter is expressed as:

[0036]

[0037] in,

[0038]

[0039] where ω s is the switching angular frequency;

[0040] The CLLLC resonant converter is defined as follows:

[0041]

[0042] If x=y=1, the converter structure can achieve bidirectional symmetry, achieve bidirectional voltage gain and control consistency, and simplify parameter design and control;

[0043] To further obtain the gain expression of the converter, it is necessary to take the normalized frequency f n =f s / f r =ω s / ω r , f s and ω s is the actual switching frequency and the corresponding angular frequency; characteristic impedance Quality factor Q = Z r / R eq , substituting the above definition into the formula, the gain expression of the converter can be obtained as:

[0044]

[0045] As a preferred solution of the NLADRC voltage control method of the high-efficiency power converter for electric vehicles of the present invention, the improved anti-integral saturation NLADRC voltage control strategy is established,

[0046] Design the voltage controller based on LADRC;

[0047] The voltage controller is designed based on the improved anti-integral windup NLADRC.

[0048] As a preferred solution of the NLADRC voltage control method of the high-efficiency power converter for electric vehicles of the present invention, wherein: the design of the voltage controller based on LADRC includes:

[0049] The CLLLC resonant converter is reduced to a second-order model, and its transfer function structure is shown in the following equation:

[0050]

[0051] According to the above formula, let y be the output quantity, that is, the secondary side output, and u be the input quantity, that is, the primary side DC voltage input, we have:

[0052]

[0053] Among them, a0, a1, c0, c1, and b0 are the undetermined coefficients in LADRC, and a0, a1, c0, and c1 are related to the mathematical model of the converter being reduced to the second order;

[0054] Choose the state variable x as Then the state variable contains the total disturbance, and the corresponding state equation is written as:

[0055]

[0056] Therefore, the third-order LESO is established as:

[0057]

[0058] Among them, β1, β2, β3 are observer parameters; z1, z2 are the observed values ​​of the system state variables, and z3 is the total disturbance observation of the controlled object; if the parameters are set appropriately, the correct state variable x can be estimated;

[0059] To achieve the desired control, the LSEF is set to:

[0060]

[0061] Among them, k p , k d is the controller parameter; r is the given target value.

[0062] As a preferred solution of the NLADRC voltage control method of the high-efficiency power converter for electric vehicles of the present invention, the design of the voltage controller based on the improved anti-integral saturation NLADRC includes:

[0063] NLADRC is implemented on the basis of LADRC by adding a nonlinear filter function as shown below:

[0064]

[0065] Among them, e is the error; α is the nonlinear factor, which represents the nonlinearity of the filter function, 0≤α≤1; δ is the filter factor, which represents the width of the linear interval;

[0066] The following function is used as the integral anti-saturation nonlinear filter function:

[0067]

[0068] Among them, e is the error, ke is the proportional coefficient with ke>0, Klim is the upper and lower limits of integration, and ε is the maximum error.

[0069] Beneficial effects of the present invention: The present invention significantly improves the anti-disturbance capability and stability by applying an improved nonlinear self-disturbance control strategy with anti-integral saturation. By using a nonlinear filter function, the strategy effectively suppresses fluctuations in the response, speeds up the stabilization speed, and improves the stability and robustness of the overall control. At the same time, the improved anti-integral saturation algorithm prevents the saturation problem of the integral term, making the voltage control more precise and enhancing the rapid response capability. These improvements can maintain stable voltage output and excellent control accuracy in the face of different load disturbances. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0071] Figure 1 This is the topology diagram of the resonant converter.

[0072] Figure 2 This is the FHA model diagram of the CLLLC resonant converter.

[0073] Figure 3 This is the converter gain curve for different k values ​​under the same Q value.

[0074] Figure 4 This is the converter gain curve for different Q values ​​under the same k value.

[0075] Figure 5 This is the LADRC control block diagram of the CLLLC resonant converter.

[0076] Figure 6 This is the Anti-reset Windup structure diagram.

[0077] Figure 7 This is the improved Anti-reset Windup structure diagram.

[0078] Figure 8 It is the image of nonlinear filtering function.

[0079] Fig. 9 The waveform diagram shows the comparison of the converter's anti-interference performance before and after using ADRC.

[0080] Fig.10 This is the output voltage waveform of the converter using improved NLADRC voltage control.

[0081] Fig.11 This is the waveform diagram of the load disturbance resistance comparison experiment. DETAILED DESCRIPTION

[0082] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0083] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0084] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0085] Example 1

[0086] Reference Figures 1 to 8 , is an embodiment of the present invention, and provides a NLADRC voltage control method for a high-efficiency power converter for an electric vehicle, comprising:

[0087] S1: Establish the equivalent model of CLLLC resonant converter based on fundamental wave analysis method.

[0088] Depend on Figure 1 It can be seen that the topological structure of CLLLC is mainly composed of three parts: inverter unit, resonant unit and rectifier unit.

[0089] Furthermore, the establishment of the CLLLC resonant converter equivalent model based on the fundamental wave analysis method includes:

[0090] The full-bridge equivalent replacement of the CLLLC resonant converter is performed, and the secondary side of the transformer is converted to the primary side to obtain the FHA model of the CLLLC resonant converter;

[0091] Where V AB_FHA It is the sine wave voltage equivalent to the voltage between the midpoints of the inverter bridge arm through FHA; L r1 and C r1 are the resonant inductance and capacitance of the primary and primary sides respectively; let n p is the transformer ratio, the resonant inductance of the secondary side converted to the primary side Resonant capacitor Req is the load obtained by equivalent the output side resistive load using FHA. The specific calculation process is given below.

[0092] Due to the switching of the switching devices in the inverter unit, the voltage between the midpoints of the bridge arms is actually V in and -V in The square wave voltage that jumps between is shown as follows:

[0093]

[0094] Among them, T s is the switching period, i.e. T s =1 / f s , where f s is the switching cycle;

[0095] Performing Fourier transform on the above equation gives the following equation:

[0096]

[0097] Where n is the integer parameter of the Fourier series expansion;

[0098] In the fundamental wave analysis method, it is believed that the energy of the input signal mainly comes from the fundamental wave component, and the remaining high-order harmonics are negligible; the fundamental wave component and its effective value can be extracted from the above formula as follows:

[0099]

[0100] Since the input of CLLLC needs to pass through the inverter unit, the current flowing through the resonant cavity is actually an alternating current. According to the idea of ​​fundamental wave analysis, it is equivalent to a sine wave as follows:

[0101]

[0102] I r1 is the transformer primary resonant current i r1 (t) effective value, Yes V AB_FHA (t) and i r1 (t) The phase difference between them, similarly, the fundamental component and effective value of the voltage between the midpoints CD of the two bridge arms of the rectifier unit are obtained:

[0103]

[0104] Where θ is the phase difference between the output side and the input side;

[0105] The current in the secondary resonant cavity is expressed as:

[0106]

[0107] Among them, I r2 is the effective value of the transformer secondary resonant current ir2(t);

[0108] The resonant cavity obtains the output current through the rectifier unit, so the output average current is:

[0109]

[0110] Among them, I o is the output current, P o is the output power, V o is the output voltage, R o is the output resistive load;

[0111] From the above formula, we can see that V CD_FHA (t) and i r2 (t) are in phase, so Ro is equivalent to the equivalent output resistance Req of the FHA model:

[0112]

[0113] S2: The voltage gain is solved by using the FHA equivalent model of the CLLLC resonant converter using the linear circuit solution method.

[0114] Furthermore, the FHA equivalent model based on the CLLLC resonant converter uses a linear circuit solution method to solve the voltage gain, including:

[0115] The voltage gain of the CLLLC resonant converter is expressed as:

[0116]

[0117] in,

[0118]

[0119] where ω s is the switching angular frequency;

[0120] The CLLLC resonant converter is defined as follows:

[0121]

[0122] The resonant network of the CLLLC resonant converter consists of five components. Theoretically, there are multiple resonance points, which increases the difficulty of parameter design and topology control. Figure 2 It can be seen that if x=y=1, the structure of the converter can achieve bidirectional symmetry, achieve bidirectional voltage gain and control consistency, and simplify parameter design and control;

[0123] To further obtain the gain expression of the converter, it is necessary to take the normalized frequency f n =f s / f r =ω s / ω r , f s and ω s is the actual switching frequency and the corresponding angular frequency; characteristic impedance Quality factor Q = Z r / R eq , substituting the above definition into the formula, the gain expression of the converter can be obtained as:

[0124]

[0125] Furthermore, according to the above formula, the frequency response gain curves of the converter with different k values ​​at the same Q value and the frequency response gain curves of the converter with different Q values ​​at the same k value are plotted as follows: Figure 3 , as shown in 4.

[0126] It should be noted that Figure 3 It can be obtained that when the quality factor Q remains unchanged, that is, when the load remains unchanged, on the one hand, as the k value increases, the maximum gain of the converter decreases, the switching frequency corresponding to the maximum gain decreases, and the under-resonance amplification region gradually becomes nonlinear. If the k value is too large, the converter will even lose its amplification ability; on the other hand, as the k value increases, the minimum gain will also increase, and the gain adjustment ability in the over-resonance region will gradually deteriorate. Therefore, from this perspective, the k value should be as small as possible to ensure that the converter has a wider gain range in the over-resonance state.

[0127] Depend on Figure 4 It can be seen that when the k value is fixed, the quality factor Q represents the severity of the load. The larger the quality factor Q, the heavier the load. At the same frequency, the voltage gain is also smaller. When the load is too heavy, in the sub-resonant region, the linear adjustment ability of the frequency to the gain will be lost, and the gain may even be less than 1. Therefore, when designing parameters, the maximum load capacity of the converter must also be considered to reasonably set the maximum quality factor.

[0128] S3: Establish an improved anti-integral saturation NLADRC voltage control strategy.

[0129] The charging process of OBC is relatively complex and requires dual closed-loop control of voltage and current loops. Similar to the speed limit loop of the motor, the voltage loop acts as a voltage limit loop to limit the charging voltage, and the current loop controls the charging current according to the power battery charging efficiency curve. For CLLLC converters, PI control is sufficient to achieve control, but the actual working conditions of OBC are complex, and there are various disturbances during operation. PI control has poor anti-interference ability and it is difficult to maintain stable operation.

[0130] Therefore, this paper proposes an improved anti-integral saturation NLADRC voltage control strategy for the load disturbance and other anti-disturbance problems of CLLLC converter, thereby improving the anti-disturbance performance of the converter. This strategy adds a nonlinear filter function on the basis of Linear Active Disturbance Rejection Control (LADRC) and adds an improved Anti-reset Windup integral anti-saturation algorithm to the integral variable inside the control system to accelerate the convergence of internal variables and accelerate system stability.

[0131] Furthermore, the improved anti-integral saturation NLADRC voltage control strategy is established, including:

[0132] Design the voltage controller based on LADRC;

[0133] The voltage controller is designed based on the improved anti-integral windup NLADRC.

[0134] Furthermore, the design of the voltage controller based on LADRC includes:

[0135] The CLLLC resonant converter is reduced to a second-order model, and its transfer function structure is shown in the following equation:

[0136]

[0137] Linear active disturbance rejection control mainly includes two parts: Extended State Observer (ESO) and Linear State Error Feedback (LSEF). ESO is the core of LADRC, which is used to estimate the current state variable according to the total disturbance of the system. LSEF is a control law similar to negative feedback. However, compared with PI control, LSEF is no longer a simple subtraction of given and feedback, but adds the differential of each order state variable, thereby making up for the shortcomings of PI in terms of rapidity. The control block diagram of LADRC is shown in the figure below: Figure 5 Shown

[0138] According to the above formula, let y be the output quantity, that is, the secondary side output, and u be the input quantity, that is, the primary side DC voltage input, we have:

[0139]

[0140] Among them, a0, a1, c0, c1, and b0 are the undetermined coefficients in LADRC, and a0, a1, c0, and c1 are related to the mathematical model of the converter being reduced to the second order;

[0141] Choose the state variable x as Then the state variable contains the total disturbance, and the corresponding state equation is written as:

[0142]

[0143] Therefore, the third-order LESO is established as:

[0144]

[0145] Among them, β1, β2, β3 are observer parameters; z1, z2 are the observed values ​​of the system state variables, and z3 is the total disturbance observation of the controlled object; if the parameters are set appropriately, the correct state variable x can be estimated;

[0146] To achieve the desired control, the LSEF is set to:

[0147]

[0148] Among them, k p , k d is the controller parameter; r is the given target value.

[0149] Furthermore, the design of the voltage controller based on the improved anti-integral saturation NLADRC includes:

[0150] NLADRC is implemented on the basis of LADRC by adding a nonlinear filter function as shown below:

[0151]

[0152] Among them, e is the error; α is the nonlinear factor, which represents the nonlinearity of the filter function, 0≤α≤1; δ is the filter factor, which represents the width of the linear interval;

[0153] It should be noted that the nonlinear filter function fal(e, α, δ) has the characteristics of small error and large gain, and large error and small gain, which ensures that the estimated value can converge faster and track the given value, and the estimated value will be relatively more stable.

[0154] It can be seen from the third-order LESO that the system variable observations and disturbance observations z1, z2, and z3 all need to be integrated from the differential estimates obtained by ESO, and all belong to integral terms, which have an important impact on the convergence, stability, and rapidity of the system. Due to the saturation problem of the integral term, this paper adopts an improved integral anti-saturation algorithm based on Anti-resetWindup, and its structure is as follows: Figure 6As shown in Figure 1, this method is simple and effective, but lacks robustness, has large compensation arbitrariness and low accuracy. Based on this, this paper improves it and sets a nonlinear filter function for the integral term to achieve the effect of amplifying small errors and saturating large errors, accelerating the integral stability and anti-saturation. The improved Anti-reset Windup structure is shown in Figure 1. Figure 7 shown.

[0155] The role of nonlinear filter function is to amplify small errors and saturate large errors. The saturation effect can accelerate the desaturation of integral to prevent the integral from infinite accumulation and divergence, while the amplification effect is to make the integral converge quickly. Conventional linear functions with upper and lower limits do not have amplification effects within the limit range, and the function transition stage is not smooth. Therefore, this paper uses the following function as the nonlinear filter function for integral anti-saturation:

[0156]

[0157] Among them, e is the error, k e k is the proportionality coefficient e >0,0<χ<1,K lim are the upper and lower limits of integration, and ε is the maximum error. The function waveform is as follows: Figure 8 shown.

[0158] In summary, the present invention accelerates the convergence of ADRC internal parameters by adding a nonlinear filtering function and an improved anti-integral saturation algorithm, inherits the excellent anti-disturbance capability of LADRC, improves the robustness and rapidity of the control system, and improves the output anti-disturbance performance to cope with complex working conditions.

[0159] Example 2

[0160] Reference Figures 9-11 , which is the second embodiment of the present invention, provides a NLADRC voltage control method for a high-efficiency power converter for electric vehicles and performs simulation verification.

[0161] Simulation and Experiment of CLLLC Resonant Converter

[0162] Simulation Analysis

[0163] like Fig. 9 The figure shows the load disturbance simulation comparison between PI control and LADRC control.

[0164] Among them, Figure (a) is the output voltage waveform of the converter based on PI control. When a load disturbance is applied at 0.1s, it can be seen that the voltage rises to 370V and then returns to stability after about 10ms; Figure (b) is the output voltage waveform of the converter based on LADRC. When the load is suddenly reduced at 0.25s, the voltage has no obvious change. It can be seen that the anti-disturbance performance of the converter is greatly improved after the use of ADRC; however, the rapidity of the converter is significantly reduced, and it takes about 0.22s to achieve stable output accompanied by about 4.1% overshoot, while the converter under PI control can complete stable control in 0.02s, and the converter under LADRC control has a voltage ripple of 4-5V after stabilization.

[0165] like Fig.10 The output voltage waveform of the NLADRC with improved anti-integration saturation is shown.

[0166] Among them, compared with LADRC, the improvement has slightly improved its speed due to the addition of filtering function and integral anti-saturation strategy. Stable voltage output can be achieved in about 0.18s, the overshoot is extremely small and can be ignored, and the output voltage ripple is relatively small at 2-3V.

[0167] Experimental verification

[0168] like Fig.11 The following are the anti-disturbance comparison waveforms of different control strategies under low voltage. Among them, Figure (a) is the anti-disturbance waveform under PI control. After the sudden load is added, the output voltage drops slightly by 2-3V, accompanied by a certain ripple; Figure (b) is based on the improved anti-integral saturation NLADRC voltage control strategy. After the disturbance occurs, the voltage fluctuation cannot be captured, and the output voltage does not change before and after the disturbance. Due to the low test voltage, the load change is not clear, but the comparison of the capture of the oscilloscope can verify the effectiveness of the proposed control strategy.

[0169] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0170] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0171] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0172] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc. It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limited. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

[0173] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A NLADRC voltage control method for a high-efficiency power converter for an electric vehicle, characterized in that: include, Establish the equivalent model of CLLLC resonant converter based on fundamental wave analysis method; The voltage gain is solved by using the FHA equivalent model of the CLLLC resonant converter and the linear circuit solution method. An improved anti-integral saturation NLADRC voltage control strategy is established.

2. The NLADRC voltage control method for a high-efficiency power converter for an electric vehicle according to claim 1, wherein: The CLLLC resonant converter equivalent model established based on the fundamental wave analysis method includes: The full-bridge equivalent replacement of the CLLLC resonant converter is performed, and the secondary side of the transformer is converted to the primary side to obtain the FHA model of the CLLLC resonant converter; where V AB_FHA It is the sine wave voltage equivalent to the voltage between the midpoints of the inverter bridge arm through FHA; L r1 and C r1 are the resonant inductance and capacitance of the primary and primary sides respectively; let n p is the transformer ratio, the resonant inductance of the secondary side converted to the primary side Resonant capacitor Req is the load obtained by using FHA to equalize the resistive load on the output side; Due to the switching of the switching devices in the inverter unit, the voltage between the midpoints of the bridge arms is actually V in and -V in The square wave voltage that jumps between is shown as follows: Among them, T s is the switching period, i.e. T s =1 / f s , where f s is the switching cycle; Performing Fourier transform on the above equation gives the following equation: Where n is the integer parameter of the Fourier series expansion; In the fundamental wave analysis method, it is believed that the energy of the input signal mainly comes from the fundamental wave component, and the remaining high-order harmonics are negligible; the fundamental wave component and its effective value are extracted as follows: Since the input of CLLLC needs to pass through the inverter unit, the current flowing through the resonant cavity is actually an alternating current. According to the idea of ​​fundamental wave analysis, it is equivalent to a sine wave as follows: I r1 is the transformer primary resonant current i r1 (t) effective value, Yes V AB_FHA (t) and i r1 (t) The phase difference between them, similarly, the fundamental component and effective value of the voltage between the midpoints CD of the two bridge arms of the rectifier unit are obtained: Where θ is the phase difference between the output side and the input side; The current in the secondary resonant cavity is expressed as: Among them, I r2 is the effective value of the transformer secondary resonant current ir2(t); The resonant cavity obtains the output current through the rectifier unit, so the output average current is: Among them, I o is the output current, P o is the output power, V o is the output voltage, R o is the output resistive load; From the above formula, we can see that V CD_FHA (t) and i r2 (t) are in phase, so Ro is equivalent to the equivalent output resistance Req of the FHA model:

3. The NLADRC voltage control method for a high-efficiency power converter for an electric vehicle as claimed in claim 2, characterized in that: The FHA equivalent model based on the CLLLC resonant converter uses a linear circuit solution method to solve the voltage gain, including: The voltage gain of the CLLLC resonant converter is expressed as: in, where ω s is the switching angular frequency; The CLLLC resonant converter is defined as follows: If x=y=1, the converter structure can achieve bidirectional symmetry, achieve bidirectional voltage gain and control consistency, and simplify parameter design and control; To further obtain the gain expression of the converter, it is necessary to take the normalized frequency f n =f s / f r =ω s / ω r , f s and ω s is the actual switching frequency and the corresponding angular frequency; characteristic impedance Quality factor Q = Z r / R eq , substituting the above definition into the formula, the gain expression of the converter can be obtained as:

4. The NLADRC voltage control method for a high-efficiency power converter for an electric vehicle as claimed in claim 3, characterized in that: The improved anti-integral saturation NLADRC voltage control strategy includes: Design the voltage controller based on LADRC; The voltage controller is designed based on the improved anti-integral windup NLADRC.

5. The NLADRC voltage control method of the high-efficiency power converter for electric vehicles as claimed in claim 4, characterized in that: The design of the voltage controller based on LADRC includes: The CLLLC resonant converter is reduced to a second-order model, and its transfer function structure is shown in the following equation: According to the above formula, let y be the output quantity, that is, the secondary side output, and u be the input quantity, that is, the primary side DC voltage input, we have: Among them, a0, a1, c0, c1, and b0 are the undetermined coefficients in LADRC, and a0, a1, c0, and c1 are related to the mathematical model of the converter being reduced to the second order; Choose the state variable x as Then the state variable contains the total disturbance, and the corresponding state equation is written as: Therefore, the third-order LESO is established as: Among them, β1, β2, β3 are observer parameters; z1, z2 are the observed values ​​of the system state variables, and z3 is the total disturbance observation of the controlled object; if the parameters are set appropriately, the correct state variable x can be estimated; To achieve the desired control, the LSEF is set to: Among them, k p , k d is the controller parameter; r is the given target value.

6. The NLADRC voltage control method of the high-efficiency power converter for electric vehicles as claimed in claim 5, characterized in that: The design of the voltage controller based on the improved anti-integral saturation NLADRC includes: NLADRC is implemented on the basis of LADRC by adding a nonlinear filter function as shown below: Among them, e is the error; α is the nonlinear factor, which represents the nonlinearity of the filter function, 0≤α≤1; δ is the filter factor, which represents the width of the linear interval; The following function is used as the integral anti-saturation nonlinear filter function: Among them, e is the error, k e k is the proportionality coefficient e >0,0<χ<1,K lim are the upper and lower limits of integration, and ε is the maximum error.

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