Active-disturbance-rejection equivalent sliding mode direct voltage control method of LCL type motor simulator

Abstract

The invention discloses an active-disturbance-rejection equivalent sliding mode direct voltage control method for an LCL type motor simulator, and belongs to the technical field of motor driving control. Voltage and current on an LCL filter are sampled, an improved VBR motor model is used for real-time calculation, and a reference value of capacitor voltage after disturbance compensation is obtained; according to the system model equation, the control rate of the equivalent sliding mode voltage control method is deduced, an extended state observer is established to carry out disturbance compensation and delay compensation on the control rate, control over the capacitor voltage is achieved, and then simulation of the voltage and current characteristics of the motor port is achieved. The improved VBR model is combined with equivalent sliding mode voltage control, the robustness and dynamic performance of LCL type motor simulator control are effectively improved, and the LCL type motor simulator can still operate stably under parameter mismatch.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor drive control, and particularly relates to an active disturbance rejection equivalent sliding mode direct voltage control method for an LCL type motor simulator. Background Technique

[0002] Motor drive and control systems play an extremely important role in industrial development. To meet the requirements of the R & D speed and quality of motor drive control systems, motor simulators, with their advantages of high efficiency, short cycle, small volume, high safety, and strong applicability, have become the most commonly used in-loop test platforms for motor drive control at present.

[0003] A motor simulator can directly replace a traditional motor mechanical bench and be connected to the motor driver under test to achieve the same port characteristics as a real motor, thus facilitating the power stage development and testing of motor drive control systems. A motor simulator mainly consists of two parts: power devices and digital control. The power devices mainly include a port filter, a power converter, and a sensor, and the digital control mainly includes a motor model, a control algorithm, and a PWM modulation algorithm. Among them, the dynamic performance and control accuracy of a motor simulator seriously depend on its port filter type and the corresponding control algorithm.

[0004] Most existing motor simulators use an L-type filter, whose main advantages are simple structure and being a first-order system, and traditional current closed-loop control algorithms can be used to control the port current. However, since the simulator and the motor driver control the same current, the current loop bandwidth of the simulator needs to be much larger than that of the driver. Otherwise, current control conflicts will occur, leading to system instability, which seriously reduces the applicability of the simulator. Therefore, an open-loop current control strategy for motor simulators was proposed, effectively solving the bandwidth problem of current control algorithms. However, the accuracy of open-loop control seriously depends on accurate modeling and hardware implementation, so control errors will inevitably occur, reducing the simulation accuracy of the simulator.

[0005] Compared with the L filter, the LCL filter is more suitable for the EME (electric motor emulator) because the introduction of the capacitive branch eliminates current control conflicts. In addition, the LCL filter has better filtering performance and simulation accuracy. However, the LCL filter has a complex structure, cumbersome control, and is prone to control oscillation. The voltage-behind-reactance (VBR) model is an effective method to reduce the control complexity of the LCL type EME because its output is the reference value of the capacitor voltage, thus converting current control into voltage control, as Figure 1As shown. However, the traditional VBR model is highly sensitive to parameters and will generate large errors in the case of parameter mismatch. After the VBR model, the next step is to ensure the accurate tracking of the capacitor voltage. The voltage-current double-loop PI control is a commonly used voltage control method, but its dynamic performance is poor. In addition, the active damping model predictive control can effectively improve the control bandwidth. However, as a model-based control, its robustness is poor under parameter mismatch and the computational load is large.

[0006] In summary, there is relatively little research on the control of existing LCL-type motor simulator systems, and most of them have problems such as complex control structures, slow dynamic responses, poor robustness, or dependence on passive damping. Summary of the Invention

[0007] The object of the present invention is to overcome the problem that oscillation and instability are likely to occur when there is a parameter mismatch in the existing LCL-type motor simulator control technology, and a self-disturbance rejection equivalent sliding mode direct voltage control method for an LCL-type motor simulator is proposed.

[0008] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a self-disturbance rejection equivalent sliding mode direct voltage control method for an LCL-type motor simulator, including the following steps: Sample the voltage and current on the LCL filter, and use the improved VBR motor model for real-time calculation to obtain the reference value of the capacitor voltage after disturbance compensation; According to the system model equation, deduce the control law of the equivalent sliding mode voltage control method, and establish an extended state observer to perform disturbance compensation and time delay compensation on the control law for realizing the control of the capacitor voltage and completing the simulation of the motor port voltage and current characteristics.

[0009] Further, the construction method of the VBR model specifically includes: establishing the voltage equation of the motor to be simulated by using the voltage of the motor port to be simulated, the reference of the current of the motor port to be simulated, the stator resistance of the motor to be simulated, the d-axis inductance, the q-axis inductance, the permanent magnet flux linkage, and the electrical angular velocity; establishing the voltage drop equation of the port-side filter inductor by using the actual port current of the simulator, the actual capacitor voltage on the filter capacitor, the inductance value and internal resistance of the port-side inductor; substituting the voltage equation of the motor to be simulated into the voltage drop equation of the port-side filter inductor to obtain the VBR model equation for real-time calculation of the reference value of the capacitor voltage.

[0010] Further, the construction method of the improved VBR model includes constructing an extended state observer according to the voltage drop equation of the port-side inductor, observing the disturbance error by using the extended state observer, and substituting the observed signal and the disturbance error into the VBR model to obtain the improved VBR model.

[0011] Furthermore, the extended state observer for observing the disturbance error is shown as follows:

[0012] where k + 1 represents the predicted value of the variable at the (k + 1)-th moment, and k represents the value of the variable at the k-th moment; is the observation error, that is, the current at the observation port of the simulator and the actual port current the error between; is the port voltage of the simulator; is the capacitor voltage of the filter; is the observed disturbance error; is the rotation factor; and are the bandwidth parameters of the extended state observer, and , is the bandwidth of this observer; is the discrete period time; Substitute the observed disturbance at the (k + 1)-th moment and the port current at the (k + 1)-th moment into the VBR model to obtain the improved VBR model: .

[0014] Furthermore, the equivalent sliding mode direct voltage control method includes establishing a second-order sliding mode surface, establishing a high-order extended state observer to observe and compensate for the disturbance in the second-order sliding mode surface, and finally obtaining the control rate of the capacitor voltage.

[0015] Furthermore, the equivalent sliding mode direct voltage control method specifically includes: Establish the filter capacitor voltage equation and the simulated-side inductor voltage drop equation, establish the equality equation of the second-order sliding mode surface according to the filter capacitor voltage equation and the simulated-side inductor voltage drop equation, control the second-order sliding mode surface to 0, obtain the control rate of the direct voltage control output of the equivalent sliding mode, and establish a third-order extended state observer for the equality equation of the second-order sliding mode surface to observe the disturbance quantity; Combine the filter capacitor voltage equation, the simulated-side inductor voltage drop equation, and the equality equation of the second-order sliding mode surface, convert the second-order sliding mode surface equation into a first-order differential equation about the output current of the simulator, and discretize the differential term using the forward Euler method to obtain the predicted value of the output current of the simulator; Substitute the predicted values of the variables and the disturbance quantity into the formula of the direct voltage control rate equation of the equivalent sliding mode to obtain the compensated control rate equation.

[0016] Furthermore, the equality equation of the second-order sliding mode surface is shown as follows:

[0017] wherein, is the difference between the actual capacitor voltage and the reference capacitor voltage of the filter; is the capacitor voltage of the filter; is the reference capacitor voltage of the filter; is the current on the analog side; is the established sliding mode surface; and are respectively the first derivative and the second derivative of ; a, b, and c are the gain coefficients of the state variables and the output variables; is the total disturbance of the system; and are the sliding mode surface coefficients; the sliding mode surface coefficients and are designed by pole placement or damping ratio frequency method, and satisfy the Hurwitz criterion.

[0018] Furthermore, the control law of the direct voltage control output of the equivalent sliding mode is:

[0019] wherein, is the output voltage of the analog converter; The third-order extended state observer is shown as follows:

[0020] wherein, is the observation error, that is, the difference between the observed quantity and the actual variable ; is the observed value of the disturbance quantity; is the observed quantity of the first derivative of ; , and are the bandwidth parameters of the extended state observer, generally configured as , and [[ID=7II]] .

[0021] Furthermore, the predicted value of the output current of the simulator is:

[0022] The control law equation is shown as follows: .

[0024] In a second aspect, the present invention provides an LCL-type motor simulator based on active disturbance rejection equivalent sliding mode direct voltage control, which uses the active disturbance rejection equivalent sliding mode direct voltage control method for the LCL-type motor simulator described above.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects: The active disturbance rejection equivalent sliding mode direct voltage control method for the LCL-type motor simulator proposed by the present invention improves the ability of the VBR model to generate an accurate capacitor voltage reference even under inductor parameter mismatch. By using equivalent sliding mode direct voltage control, the capacitor voltage can quickly and accurately track the voltage reference signal, and finally a control law with delay compensation and disturbance compensation is obtained, that is, the given voltage signal of the simulator converter, which solves the problems of easy oscillation and instability in the existing LCL-type motor simulator control technology under parameter mismatch, the complexity of the multi-closed-loop control structure and the difficulty of parameter tuning, as well as the low control bandwidth and dynamic response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure of the present invention in any way. Additionally, the shapes and proportional dimensions of the components in the figures are only schematic and are used to assist in understanding the present invention, rather than specifically defining the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 is the control structure block diagram of the LCL-type motor simulator based on the traditional VBR model; Figure 2 is the control structure block diagram of the motor simulator control system of the present invention.

[0027] Figure 3 is the control flow chart of the motor simulator of the present invention.

[0028] Figure 4 is the comparison result diagram of the dynamic performance of voltage control without parameter mismatch.

[0029] Figure 5 is the comparison result diagram of the robustness of voltage control under parameter mismatch.

[0030] Figure 6 is the comparison experimental result diagram of the robustness of the improved VBR motor model under parameter mismatch. DETAILED DESCRIPTION OF THE INVENTION

[0031] To enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solution in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0032] It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there may also be a middle element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a middle element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0034] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned accompanying drawings are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0035] Embodiment 1 An active disturbance rejection equivalent sliding mode direct voltage control method for an LCL type motor simulator. The system structure diagram of the motor simulator using the active disturbance rejection equivalent sliding mode direct voltage control method proposed by the present invention is as Figure 2As shown in the figure. Inside the left border line in the figure is the motor drive unit to be measured, and inside the right border line is the motor simulator system using the active disturbance rejection equivalent sliding mode direct voltage control method of the LCL type motor simulator of the present invention. The hardware part of the simulator mainly includes an LCL filter, a power converter, and voltage and current sensors. The software part mainly includes an improved VBR motor model, a direct voltage control algorithm based on equivalent sliding mode, and a modulation strategy.

[0036] Among them, the LCL filter is responsible for isolating the motor simulator from the motor drive unit. The motor simulator simulates the current and voltage characteristics of the motor port by controlling the output current and capacitor voltage in the LCL filter. It should be known that the principles and methods such as the topological structure of the LCL filter, the topological structure of the power converter, and its modulation strategy are well known to those skilled in the art and will not be elaborated here.

[0037] The proposed control scheme mainly includes two steps. First, sample the port voltage and current and the capacitor voltage, and perform real-time calculation through the improved VBR motor model to obtain the reference value of the capacitor voltage. Then, according to this voltage reference value, use the equivalent sliding mode voltage control to control the capacitor voltage, so as to simulate the port voltage and current by controlling the capacitor voltage.

[0038] Step 1: Based on the voltage equation of the permanent magnet synchronous motor and the voltage equation of the filter on the port side, establish a VBR model. The input of the VBR model is the port voltage and current of the simulator, and the output is the reference of the capacitor voltage, which is used as the command signal for subsequent voltage control. Since there are parameter mismatches and other unmodeled errors in the VBR model, an extended state observer is designed to observe the errors, and the observed signals and errors are substituted into the traditional VBR model, so as to obtain an improved VBR model, which can also output an accurate reference of the capacitor voltage under parameter mismatches.

[0039] Step 2: In order to control the capacitor voltage to quickly and accurately track the reference of the capacitor voltage, the present invention proposes a direct voltage control based on equivalent sliding mode. Establish a second-order sliding mode surface and design a control law to directly control the capacitor voltage. Since there are also parameter mismatches and other unmodeled errors in the voltage control, the control accuracy and dynamic performance seriously depend on the error observer. Therefore, a high-order extended state observer is designed to observe and compensate the disturbance error in the sliding mode surface, and finally realize the active disturbance rejection equivalent sliding mode direct voltage control.

[0040] The establishment of the improved VBR model described in Step 1 mainly includes the following steps: 1.1. The Permanent Magnet Synchronous Motor (PMSM) has the advantages of high power density, high efficiency, large torque, etc., and has been widely used in many fields. Therefore, without loss of generality, the PMSM is taken as an example to demonstrate the superiority of the proposed control method. The mathematical model of the permanent magnet synchronous motor in the simulator is as follows: (1.1) Where, and are the motor terminal voltages; and are the motor terminal current references. , , , and are the stator resistance, d-axis inductance, q-axis inductance, permanent magnet flux linkage, and electrical angular velocity of the simulated motor, respectively.

[0041] 1.2. The equation of the voltage drop across the port-side filter inductor is: (1.2) Where, and are the actual port currents of the simulator, and are the actual capacitor voltages across the filter capacitors, and are the inductance value and internal resistance of the port-side inductor, respectively.

[0042] 1.3. Thus, it can be seen that if we want to control the actual port currents and of the simulator to be equal to the port current references and , we only need to control the actual capacitor voltages and to be equal to the reference capacitor voltages and . Let and be equal to and , and substitute Equation (1.1) into Equation (1.2), then the reference capacitor voltages and at this time can be obtained. This equation is also called the VBR model equation, as follows: (1.3) 1.4. Taking the d-axis as an example, analyze the error of the voltage reference under parameter mismatch. Rewrite Equation (1.2) as Equation (1.4). It can be seen that when the parameters are accurate, the voltage reference is . When the parameters are mismatched, that is, the actual inductance and resistance change due to the operating conditions to and , so the original inductance and resistance and The calculated voltage reference is no longer accurate.

[0043] (1.4) where is the voltage reference after disturbance compensation, and are the change amounts of the inductance and resistance under parameter mismatch; is the equivalent disturbance error under parameter mismatch.

[0044] Considering the voltage reference under parameter mismatch has been given in Equation (1.4). It can be seen that on the original basis, an error caused by the change amounts of the inductance and resistance and is added. And this error is equivalent to , and the calculation formula of the voltage reference considering parameter mismatch can be obtained, that is .

[0045] 1.5. Next, an extended state observer will be designed to observe this disturbance error. Since the dq axes are symmetric, that is, the following equations can be used for both the d-axis and the q-axis. Therefore, the formulas in the following text are all expressed in vectors, that is , and the same applies to other vector symbols. According to Equation (1.2), establish the following discrete extended state observer: (1.5) where, "(k + 1)" represents the predicted value of the variable at the (k + 1)th moment, and "(k)" represents the value of the variable at the kth moment; is the observation error, that is, the error between the observed port current of the simulator and the actual port current ; is the port voltage of the simulator; is the capacitor voltage of the filter; is the observed disturbance error; is the rotation factor; and are the bandwidth parameters of the extended state observer, usually configured as and , is the bandwidth of this observer; is the discrete periodic time.

[0046] 1.6. Substitute the disturbance observed at time k + 1 and the port current into Equation (1.3). Since the change in the port voltage is relatively slow, it is assumed that , and finally the improved VBR model is obtained: (1.6) Furthermore, the direct voltage control with auto-disturbance rejection equivalent sliding mode described in Step 2 mainly includes the following steps: 2.1. Since the dq axes are symmetric, the filtering capacitor voltage equation and the simulated-side inductor voltage drop equation can be expressed as: (1.7) where is the controlled capacitor voltage; is the output voltage of the analog converter; is the output current of the analog converter; is the rotation factor; , , are the gains of the variables, set for the simplicity of subsequent calculations; is the disturbance quantity in the filtering capacitor voltage equation; is the disturbance quantity in the simulated-side inductor voltage drop equation.

[0047] 2.2. The values of the variable gains and disturbance quantities in Equation (1.7) are given as follows: (1.8) where and are the change amounts of the inductance value and resistance of the inductor measured by the analog converter; is the change amount of the filtering capacitor.

[0048] 2.3. Using the idea of equivalent sliding mode control, establish a second-order sliding surface according to Equation (1.7): (1.9) where , that is, the difference between the actual capacitor voltage and the reference capacitor voltage; , that is, the simulated-side current; is the established sliding surface; and are the sliding surface coefficients; and are respectively The first derivative and the second derivative of

[0049] The sliding mode surface coefficient in equivalent sliding mode direct voltage control and are designed by pole placement or damping ratio frequency method, and it is necessary to ensure that and , satisfying the Hurwitz criterion. Finally, it is also necessary to combine the mathematical model of the controlled object and make a trade-off between the response speed and robustness of the control to obtain the best control effect.

[0050] 2.4. Next, the sliding mode surface equation of voltage control is derived. From Equation (1.7), we can obtain: (1.10) Combining Equation (1.9) and Equation (1.10), and assuming that the first derivative and the second derivative of the voltage reference value are both 0, that is and the value of is 0, we can obtain the equation: (1.11) where a, b, and c are the gain coefficients of the state variables and the output quantity; is the total disturbance of the system.

[0051] From this, the equation of the sliding mode surface can be obtained as: (1.12) 2.5. Therefore, when the sliding mode surface is controlled to 0, at this time is also equal to 0, that is, the actual capacitor voltage is equal to the reference capacitor voltage, realizing accurate tracking of the capacitor voltage. Thus, the control law of the output of the equivalent sliding mode direct voltage control can be obtained as: (1.13) 2.6. To observe the disturbance quantity quickly and accurately, a discretized third-order extended state observer for the sliding mode surface equation of Equation (1.12) is established as follows: (1.14) where is the observation error, that is, the difference between the observed quantity and the actual variable ; is the observed value of the disturbance quantity; is the observed quantity of the first derivative of ; , and are the bandwidth parameters of the extended state observer, generally configured as , and .

[0052] 2.7. Due to the one - beat delay in the digital controller, to compensate for the error caused by this delay, the discretized control rate equation should be the output at the (k + 1) moment. Combining Equation (1.7) and Equation (1.12), the sliding - mode surface equation can be converted into a first - order differential equation about the output current of the simulator: (1.15) Discretize the differential term using forward Euler, that is , and the predicted value of the output current of the simulator can be obtained: (1.16) 2.8. Since the change of the capacitor voltage is relatively slow, so assume , and substitute the predicted values of the variables and the disturbance quantity into the control rate equation in Step 3, the discretized control rate equation can be obtained as: (1.17) The output of this control rate is the given voltage of the converter in the simulator.

[0053] Furthermore, the superiority of the method proposed in the present invention is verified by simulation.

[0054] 3.1. A simulation model for the co - driving experiment of the motor drive unit and the real motor is built to compare with the motor simulator to verify the simulation accuracy of the port voltage and current of the motor simulator. The operating conditions are defined as follows: The motor runs at an initial speed of 1900 rpm. Then at 0.05 s, the speed command suddenly changes to 2000 rpm. The motor stabilizes after a short period of full - power acceleration.

[0055] 3.2. The experimental results of the dynamic performance comparison of voltage control without parameter mismatch are as Figure 4 shown. To verify the effectiveness of (c) in the present invention Figure 4 , the traditional voltage - current double - loop PI control Figure 4 in (a) and the active - damping model predictive control Figure 4In (b), it is a comparative experiment. The dashed line represents the simulated voltage and current waveforms of the actual motor. After the speed command suddenly changes at 0.05 s, obvious dynamic tracking errors occur in the terminal voltage and current under the double-loop PI control. The maximum current error is 1 A, and the maximum voltage error is 30 V. In contrast, the dynamic errors of the active damping model predictive control and the method of the present invention are smaller, the response speed is faster, the maximum current error is 0.5 A, and the maximum voltage error is 10 V. Moreover, the dynamic response speed of the method of the present invention is slightly higher than that of the active damping model predictive control, which proves its superior dynamic performance.

[0056] 3.3. The comparative experimental results of the voltage control robustness under parameter mismatch are as Figure 5 shown. The traditional voltage-current double-loop PI control Figure 5 in (a) and the active damping model predictive control Figure 5 in (b) are used as comparative experiments. Among them, the parameter mismatch situation is set to , and , , and are the modeling parameters in the control algorithm, , and are the actual parameters of the LCL filter.

[0057] It can be seen from Figure 5 that the parameter mismatch has little effect on the dynamic accuracy and steady-state performance of the double-loop PI control, but it will reduce its stability margin and cause voltage oscillation. Compared with the double-loop PI, the active damping model predictive control, which is a model-based control, is more affected by parameter mismatch. The interface voltage error is 20 V at steady state and up to 80 V at maximum during the dynamic process, seriously reducing its control performance. However, in the case of parameter mismatch, the equivalent sliding mode direct voltage control Figure 5 in (c) of the present invention is hardly affected, remains unchanged, and still maintains high dynamic performance and steady-state accuracy.

[0058] 3.4. To more clearly verify the effectiveness of the improved VBR model, the voltage control adopts the equivalent sliding mode direct voltage control proposed in this paper with the same control parameters. Then, comparative experiments under parameter mismatch are carried out using the traditional VBR model and the improved VBR model The comparative experimental results of the robustness of the improved VBR motor model under parameter mismatch are as Figure 6 shown. It can be seen that in the traditional VBR model Figure 6In (a) thereof, the inductor error on the port side results in a large output voltage reference error, seriously reducing the analog accuracy and dynamic performance, and may cause system instability. In contrast, the improved VBR model Figure 6 in (b) can maintain high analog accuracy and robustness even under parameter mismatches.

[0059] The present invention first establishes an improved VBR model according to the voltage equation of the motor to be simulated and the voltage drop equation of the inductor on the port side, which is used to generate a capacitor voltage reference signal. Then, in order to compensate for the error caused by the parameter mismatch of the inductor on the port side, an extended state observer is established to observe and compensate for the disturbance error of the traditional VBR model, so as to obtain an improved VBR model, enabling the VBR model to generate an accurate capacitor voltage reference even under inductor parameter mismatches. Then, a second-order sliding mode surface is established, and a high-order extended state observer is established to observe and compensate for the disturbance in the sliding mode surface. Finally, the proposed direct voltage control based on equivalent sliding mode is adopted to enable the capacitor voltage to quickly and accurately track the voltage reference signal, and finally obtain a control law with delay compensation and disturbance compensation, that is, the given voltage signal of the simulator converter. Furthermore, according to the voltage equation of the motor to be simulated and the inductor voltage drop equation on the driver side, a VBR model is established to generate a capacitor voltage reference signal. This process effectively reduces the control of the third-order system of the LCL filter to the voltage control of the second-order system, reducing the difficulty and complexity of the control algorithm design. At the same time, as the control order of the system decreases, the stability and dynamic performance of the system are also improved.

[0060] Furthermore, when there is a parameter mismatch of the inductor on the port side, the capacitor voltage reference signal output by the traditional VBR model will also be inaccurate, resulting in a reduction in the control accuracy of the system and even oscillations. By establishing an extended state observer equation for disturbance observation and compensation, an improved VBR model is obtained, enabling it to generate an accurate capacitor voltage reference even under inductor parameter mismatches, improving the control accuracy and stability of the system.

[0061] Furthermore, the direct voltage control based on equivalent sliding mode is adopted to enable the capacitor voltage to quickly and accurately track the voltage reference signal. Compared with the cascade control structure of the voltage-current double closed-loop, the direct voltage control can effectively improve the dynamic performance and control bandwidth of the system, and reduce the parameter tuning difficulty in the multi-closed-loop control.

[0062] Even further, there is also a disturbance error caused by the mismatch between the capacitor and the inductor on the simulator side in the direct voltage control, and the observation bandwidth of the disturbance error directly affects the control accuracy and response speed of the direct voltage control under parameter mismatches. To improve the observer bandwidth, a high-order extended state observer is established for error observation and compensation, effectively improving the control accuracy and response speed of the direct voltage control.

[0063] Embodiment 2 An LCL-type motor simulator based on active disturbance rejection equivalent sliding mode direct voltage control uses the active disturbance rejection equivalent sliding mode direct voltage control method of an LCL-type motor simulator in Embodiment 1.

[0064] Upon reading the above description, many embodiments and many applications beyond the provided examples will be apparent to those skilled in the art. Therefore, the scope of this teaching should not be determined with reference to the above description, but rather should be determined with reference to the full scope of the foregoing claims and the equivalents thereof. For the sake of completeness, all articles and references, including patent applications and published announcements, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to abandon such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

[0065] The above content is a further detailed description of the present invention. It cannot be determined that the specific implementation of the present invention is limited thereto. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the scope of protection determined by the present application.

Claims

1. A self-disturbance rejection equivalent sliding mode direct voltage control method for an LCL type motor simulator, characterized in that, Including the following steps: Sampling the voltage and current on the LCL filter, and performing real-time calculation using an improved VBR motor model to obtain the reference value of the capacitor voltage after disturbance compensation; According to the system model equation, deriving the control law of the equivalent sliding mode voltage control method, and establishing an extended state observer to perform disturbance compensation and delay compensation on the control law for realizing the control of the capacitor voltage and completing the simulation of the motor terminal voltage and current characteristics.

2. The auto-disturbance rejection equivalent sliding mode direct voltage control method of an LCL type motor simulator according to claim 1, characterized in that The construction method of the VBR model specifically includes: establishing the voltage equation of the motor to be simulated by using the voltage of the motor terminal to be simulated, the reference of the current of the motor terminal to be simulated, the stator resistance of the motor to be simulated, the d-axis inductance, the q-axis inductance, the permanent magnet flux linkage, and the electrical angular velocity; establishing the voltage drop equation of the port-side filter inductor by using the actual port current of the simulator, the actual capacitor voltage on the filter capacitor, the inductance value and internal resistance of the port-side inductor; substituting the voltage equation of the motor to be simulated into the voltage drop equation of the port-side filter inductor to obtain the VBR model equation for real-time calculating the reference value of the capacitor voltage.

3. The auto-disturbance rejection equivalent sliding mode direct voltage control method for an LCL type motor simulator according to claim 1, wherein The construction method of the improved VBR model includes constructing an extended state observer according to the voltage drop equation of the port-side inductor, observing the disturbance error by using the extended state observer, and substituting the observed signal and the disturbance error into the VBR model to obtain the improved VBR model.

4. The auto-disturbance rejection equivalent sliding mode direct voltage control method for an LCL type motor simulator according to claim 3, characterized in that, The extended state observer for observing the disturbance error is shown as follows: Among them, k + 1 represents the predicted value of the variable at the (k + 1)-th moment, and k represents the value of the variable at the k-th moment; is the observation error, that is, the current of the observation port of the simulator and the actual port current between the errors; is the port voltage of the simulator; is the capacitor voltage of the filter; is the observed disturbance error; is the rotation factor; and are the bandwidth parameters of the extended state observer, and , is the bandwidth of this observer; is the discrete period time; The disturbance observed at time k+1 and the port current at time k+1 are substituted into the VBR model to obtain the improved VBR model: 。 5. The auto-disturbance rejection equivalent sliding mode direct voltage control method of an LCL type motor simulator according to claim 1, characterized in that, The equivalent sliding mode direct voltage control method includes establishing a second-order sliding mode surface, establishing a high-order extended state observer to observe and compensate the disturbance in the second-order sliding mode surface, and finally obtaining the control law of the capacitor voltage.

6. The auto-disturbance rejection equivalent sliding mode direct voltage control method for an LCL type motor simulator according to claim 5, characterized in that The equivalent sliding mode direct voltage control method specifically includes: Establishing the filter capacitor voltage equation and the simulation-side inductor voltage drop equation, establishing the equality equation of the second-order sliding mode surface according to the filter capacitor voltage equation and the simulation-side inductor voltage drop equation, controlling the second-order sliding mode surface to 0 to obtain the control law of the direct voltage control output of the equivalent sliding mode, and establishing a third-order extended state observer for observing the disturbance quantity for the equality equation of the second-order sliding mode surface; Combining the filter capacitor voltage equation, the simulation-side inductor voltage drop equation, and the equality equation of the second-order sliding mode surface, converting the second-order sliding mode surface equation into a first-order differential equation about the output current of the simulator, and discretizing the differential term by using the forward Euler method to obtain the predicted value of the output current of the simulator; Substituting the predicted values of the variables and the disturbance quantity into the formula of the direct voltage control law equation of the equivalent sliding mode to obtain the compensated control law equation.

7. The auto-disturbance rejection equivalent sliding mode direct voltage control method for an LCL type motor simulator according to claim 6, wherein The equality equation of the second-order sliding mode surface is shown as follows: Wherein, is the difference between the actual capacitor voltage and the reference capacitor voltage of the filter, is the capacitor voltage of the filter, is the reference capacitor voltage of the filter; is the analog side current; is the established sliding mode surface; and are respectively 's first derivative and second derivative; a, b, and c are gain coefficients of state variables and output quantities; is the total disturbance of the system; and are sliding mode surface coefficients; the sliding mode surface coefficients and are designed by pole placement or damping ratio frequency method, and , satisfying the Hurwitz criterion.

8. The auto-disturbance rejection equivalent sliding mode direct voltage control method of an LCL type motor simulator according to claim 7, characterized in that The control law of the direct voltage control output of the equivalent sliding mode is: Among them, is the output voltage of the analog converter; The third-order extended state observer is shown as follows: wherein, is the observation error, i.e., the difference between the observed quantity and the actual variable ; is the observed value of the disturbance quantity; is the observed quantity of the first derivative of; , and are the bandwidth parameters of the extended state observer, generally configured as , and .

9. The auto-disturbance rejection equivalent sliding mode direct voltage control method for an LCL type motor simulator according to claim 8, characterized in that, The predicted value of the output current of the simulator is: The control law equation is shown as follows: 。 10. An LCL-type motor simulator based on active disturbance rejection equivalent sliding mode direct voltage control, characterized in that, Using the active disturbance rejection equivalent sliding mode direct voltage control method of an LCL-type motor simulator according to any one of claims 1-9.

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