A method for constructing a direct torque control system of an asynchronous motor based on Modelica

Abstract

The present invention provides a method for constructing an asynchronous motor direct torque control system based on Modelica. The method comprises the following steps: decomposing the asynchronous motor direct torque control system into a plurality of universal basic models, a single-machine device model and a system model according to the physical characteristics and functions of the asynchronous motor direct torque control system structure; constructing the universal basic model using Modelica, wherein the universal basic model is a universal minimum structural unit in the asynchronous motor direct torque control system; constructing a connector using Modelica, wherein the connector is used to realize information transmission between the universal basic models and between the universal basic model and external devices; constructing the single-machine device model based on the universal basic model and the connector, wherein the single-machine device model is formed by combining and connecting the universal basic models; and constructing the system model based on the single-machine device model and according to the topological structure of the asynchronous motor direct torque control system using Modelica, wherein the system model is formed by combining and connecting the single-machine device models.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a method for constructing a Modelica-based asynchronous motor direct torque control system. Background Art

[0002] Asynchronous motors have nonlinear, strongly coupled, and multivariable properties. To achieve high dynamic speed regulation performance, it is necessary to start with their dynamic model, analyze the control laws of the asynchronous motor's torque and flux, and research high-performance speed regulation schemes for these motors. The asynchronous motor direct torque control system, a mature and applied high-performance AC motor speed regulation system based on dynamic models, relies on the basic control principle of utilizing the stator flux amplitude and torque deviations. Based on the position of the stator flux vector, the appropriate voltage space vector is directly selected to reduce the deviations in flux amplitude and torque, thereby achieving control of the motor's stator flux and electromagnetic torque.

[0003] At present, the direct torque control method of asynchronous motors follows the idea of procedural modeling (also known as causal modeling) in engineering simulation applications, and uses process-oriented programming languages such as M language and C language to solve the model. Its characteristics are that users are required to manually derive and decompose the model, clarify the order of solving equations, and master the decoupling, compilation and solution techniques of complex asynchronous motor control systems. Finally, a corresponding model is established after decomposition and deformation. As a result, the model topology structure is far from the topology structure of the actual physical system. In addition, the reusability and scalability of the developed model are poor, the overall modeling workload is large, and work efficiency is reduced, making it unsuitable for physical modeling.

[0004] Since the 21st century, physical modeling systems characterized by multi-domain unified modeling, declarative non-causal modeling, and object-oriented modeling have become a key development direction in the field of modeling and simulation. Therefore, using declarative modeling systems to provide a complete, practical, easy-to-understand, reusable, and efficient method for direct torque control of asynchronous motors that reflects the actual physical system is an urgent challenge. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problems caused by the use of procedural modeling ideas in the prior art to construct an asynchronous motor direct torque control system, such as high development difficulty, poor model reusability, low engineering efficiency, and a model topology structure that is far different from the topology structure of the actual physical system.

[0006] In order to solve the above technical problems, the present invention provides a method for constructing an asynchronous motor direct torque control system based on Modelica, comprising the following steps: decomposing the asynchronous motor direct torque control system into a plurality of universal basic models, single-machine device models, and a system model according to the physical characteristics and functions of the asynchronous motor direct torque control system structure; constructing the universal basic model using Modelica, wherein the universal basic model is the universal minimum structural unit in the asynchronous motor direct torque control system; constructing a connector using Modelica, wherein the connector is used to realize information transmission between the universal basic models and between the universal basic model and external devices; constructing the single-machine device model based on the universal basic model and the connector using Modelica, wherein the single-machine device model is composed of the universal basic models combined and connected; and constructing the system model based on the single-machine device model and according to the topological structure of the asynchronous motor direct torque control system using Modelica, wherein the system model is composed of the single-machine device models combined and connected.

[0007] Optionally, the method for constructing the asynchronous motor direct torque control system based on Modelica is implemented through the MWorks platform.

[0008] Optionally, the method for constructing a stand-alone device model includes: using Kirchhoff's law, motor equivalent circuit and / or control strategy theory to convert the physical model corresponding to the stand-alone device model into a mathematical model expressed by equations; using a modeling software platform and Modelica to convert the mathematical model into a Modelica model corresponding to the stand-alone device.

[0009] Optionally, after constructing the stand-alone device model, it also includes: simulating and verifying the stand-alone device model, and judging whether the simulation results are consistent with the expected theoretical results by comparison; if the simulation results are inconsistent with the expected theoretical results, modifying the model topology, parameter configuration and / or model granularity of the stand-alone device model until the simulation results are consistent with the expected theoretical results.

[0010] Optionally, after constructing the system model, it also includes: simulating and verifying the system model, and judging whether the simulation results are consistent with the expected theoretical results by comparison; if the simulation results are inconsistent with the expected theoretical results, adjusting the system model until the simulation results are consistent with the expected theoretical results.

[0011] Optionally, after constructing the system model, the method further includes: performing simulation analysis on the asynchronous motor direct torque system model to obtain required information and knowledge.

[0012] Optionally, the general basic model includes an interface model, a common component model and / or a stand-alone device component model, the connector includes an electrical connector, a mechanical connector, a thermal connector and / or a physical quantity interface connector, the stand-alone device model includes a motor controller, a speed regulator and / or a hysteresis controller, and the system model includes a motor controller test model, a hysteresis controller test model and / or an asynchronous motor direct torque system model.

[0013] Optionally, the interface model includes a single-phase electrical interface, a three-phase electrical interface, a rotating mechanical interface and / or a physical quantity interface, the common component model includes an integration module, a diode, a grounding and / or a lookup table module, and the stand-alone device component model includes a flux calculation module, a torque calculation module, a PWM generator, a regulator model, a hysteresis controller and / or a motor controller.

[0014] The technical solution of the present invention has the following advantages:

[0015] The present invention provides a method for constructing an asynchronous motor direct torque control system based on Modelica, comprising the following steps: decomposing the asynchronous motor direct torque control system into a plurality of universal basic models, single-machine device models, and a system model according to the physical characteristics and functions of the asynchronous motor direct torque control system structure; constructing the universal basic model using Modelica, wherein the universal basic model is a universal minimum structural unit in the asynchronous motor direct torque control system; constructing a connector using Modelica, wherein the connector is used to realize information transmission between the universal basic models and between the universal basic model and external devices; constructing the single-machine device model based on the universal basic model and the connector using Modelica, wherein the single-machine device model is formed by combining and connecting the universal basic models; and constructing the system model based on the single-machine device model and according to the topological structure of the asynchronous motor direct torque control system using Modelica, wherein the system model is formed by combining and connecting the single-machine device models.

[0016] The above method implements declarative modeling by constructing an asynchronous motor direct torque control system using the Modelica language. As a unified, multi-domain modeling language based on equations, object-oriented programming, and featuring powerful component-based modeling capabilities, Modelica meets the needs of the development of modeling and simulation. It is suitable for modeling and simulating various subsystem models, including mechanical, electrical, hydraulic, thermal, and control systems, as well as large-scale, complex physical systems. Furthermore, Modelica models utilize mathematical descriptions based on differentials, algebra, and discrete equations, offering universality, openness, and standardization. Furthermore, by combining declarative and object-oriented modeling, they offer excellent reusability, reconfigurability, and scalability. This reduces development difficulty, increases reusability, improves efficiency, and enables the system to reflect actual physical systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A flowchart of a method for constructing a direct torque control system of an asynchronous motor based on Modelica provided in one embodiment of the present invention;

[0019] Figure 2 This is a general structural diagram of a model library of a direct torque control system of an asynchronous motor provided in one embodiment of the present invention;

[0020] Figure 3 A tree diagram of a model library of a direct torque control system of an asynchronous motor provided in one embodiment of the present invention;

[0021] Figure 4 A model diagram of a direct torque control system for an asynchronous motor provided in one embodiment of the present invention;

[0022] Figure 5 A diagram of a compilation and solution process of a direct torque control system of an asynchronous motor provided in one embodiment of the present invention;

[0023] Figure 6 This is a diagram showing the effect of an asynchronous motor direct torque control system provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] An embodiment of the present invention provides a method for constructing a direct torque control system of an asynchronous motor based on Modelica, referring to Figure 1 , Figure 1 This is a flowchart of a method for constructing a Modelica-based asynchronous motor direct torque control system according to one embodiment of the present invention. It should be understood that the method may include additional blocks not shown and / or may omit the blocks shown, and the scope of the present invention is not limited in this respect. The method includes the following steps:

[0027] In step 101 , the asynchronous motor direct torque control system is decomposed into a number of general basic models, single-machine equipment models and system models according to the physical characteristics and functions of the asynchronous motor direct torque control system structure.

[0028] Specifically, the asynchronous motor direct torque control system includes an asynchronous motor, a motor controller, a load, an inverter, a DC power supply, a torque calculation module, a flux calculation module, a position sensor, etc. On the basis of fully considering the reusability of the model, the asynchronous motor direct torque control system is decomposed based on the idea of data abstraction, interface separation, and modular design decomposition, and according to the actual topology of the system. The data abstraction, that is, extracting the common features in the model and expressing them with an abstract model, is an important means to improve the reusability of the model. The interface separation, that is, modeling different components and device models separately, and declaring component properties during the model instantiation process. The modular design decomposition includes the interface model of the asynchronous motor direct torque control system, various component models, single-machine device model, system model, etc.

[0029] In some embodiments, before performing system decomposition, it is also necessary to: (1) determine the model target. According to the task of the asynchronous motor control system, determine the target and extended use of the system model, and clarify the information that must be obtained through the model and the information that the model does not need to consider. The control task can be the speed regulation, position regulation, etc. of the motor. The system target can be the speed following or position following error is less than 5%. The extended use is mainly the simulation application of asynchronous motor engineering, which can be used for generator simulation of wind power system, simulation of new energy vehicle drive motor system, etc.; (2) construct a conceptual model. The conceptual model is the principle block diagram of the asynchronous motor control system. It is to assist in analyzing the principles and mechanisms of the main phenomena of the system, helping engineers to fully understand the physical system and reflect the modeling ideas.

[0030] Based on the above decomposition ideas, refer to Figure 2 Based on the physical characteristics and functions of the asynchronous motor direct torque control system structure, the asynchronous motor direct torque control system is decomposed into a general basic model, a single-machine device model, and a system model. Based on this decomposition, for modeling purposes, the first-layer objects are further decomposed, and the single-machine component model, interface model, controller model, and system model are sequentially categorized. In some embodiments, the general basic model includes an interface model, a common component model, and / or a single-machine device component model. The single-machine device model includes a motor controller, a speed regulator, and / or a hysteresis controller. The system model includes a motor controller test model, a hysteresis controller test model, and / or an asynchronous motor direct torque system model.

[0031] At step 102 , the universal basic model is constructed using Modelica. The universal basic model is a universal minimum construction unit in the asynchronous motor direct torque control system.

[0032] Specifically, the basic model is the smallest building block in the asynchronous motor direct torque control system model library. Basic models can be connected to construct the upper-level model, while component models are usually composed of more general basic models. The principle of dividing the two is to start with a simple model and gradually increase the model complexity as needed. In some embodiments, the general basic models of the asynchronous motor direct torque control system model library are interface models, common component models, stand-alone device component models, etc. The interface model represents the input and output characteristics of each component and the transmission relationship between components, including single-phase electrical interfaces, three-phase electrical interfaces, rotating machinery interfaces and / or physical quantity interfaces. The common component model represents the inherent characteristics of the elements or devices shared by each stand-alone device, including integration modules, diodes, grounding and / or lookup modules. The stand-alone device component model represents the electrical properties of the actual physical stand-alone device in the asynchronous motor direct torque control system, including flux calculation modules, torque calculation modules, PWM generators, regulator models, hysteresis controllers and / or motor controllers.

[0033] In step 103 , Modelica is used to construct a connector, which is used to implement information transmission between the universal basic models and between the universal basic model and external devices.

[0034] Specifically, the various components within the general base model communicate with other components or the external world through connectors. This connection automatically establishes voltage and current balance equations within the system. Connectors contain the various physical quantities that need to be described, such as voltage and current in electronic components, angle and torque in drive components, and pressure and flow in hydraulic fluid components. This phase requires designing all connectors for the asynchronous motor direct torque control system model and determining a reasonable set of connector variables. Connectors should simplify and naturally connect the general base models. Connectors for physical component models must ensure that component connections are physically possible. There are four types of connectors for the asynchronous motor direct torque control system model, as shown in Table 1. These primarily include electrical connectors, mechanical connectors, thermal connectors, and / or physical quantity interface connectors. The first three types of connectors are specialized interfaces containing flow and potential variables and satisfying generalized Kirchhoff's laws. Physical quantity interfaces primarily include real and Boolean interfaces. Connectors of the same type can be freely connected as needed, generating non-causal connection equations without requiring a specific solution order.

[0035] Table 1

[0036]

[0037]

[0038] At step 104 , the stand-alone device model is constructed using Modelica based on the universal basic model and the connector. The stand-alone device model is formed by combining and connecting the universal basic models.

[0039] Specifically, each single-machine device model of the asynchronous motor direct torque control system is independently established using an object-oriented declarative modeling method and is independent of the external environment.

[0040] In some embodiments, the method for constructing the stand-alone device model includes: first, converting the physical model corresponding to the stand-alone device model into a mathematical model expressed in equations using Kirchhoff's laws, motor equivalent circuits and / or control strategy theoretical knowledge, and converting the mathematical model into a Modelica model of the corresponding stand-alone device using a modeling software platform and Modelica. Each mathematical equation of the stand-alone model is independently written in the most natural form, without specifying the input and output variables and the order in which the equations are solved, and has non-causal characteristics. The equations are as consistent as possible with the form in books and literature to ensure readability and knowledge accumulation. Subsequently, all stand-alone device models are established one by one, and the models are classified and managed in the form of a model library to obtain the following: Figure 3 The tree diagram of the model library of the asynchronous motor direct torque control system is shown.

[0041] In some embodiments, after constructing the stand-alone device model, it also includes: simulating and verifying the stand-alone device model, and judging whether the simulation results are consistent with the expected theoretical results by comparison; if the simulation results are inconsistent with the expected theoretical results, modifying the model topology, parameter configuration and / or model granularity of the stand-alone device model until the simulation results are consistent with the expected theoretical results.

[0042] Specifically, the designed and constructed stand-alone device model needs to be connected to the test model for simulation verification, and the simulation results are compared with the expected theoretical results. If the two are consistent, it means that the stand-alone device model is verified; if the two are inconsistent, the reasons for the inconsistency include high granularity of stand-alone device modeling, unreasonable model parameter configuration, and inconsistency between the internal topology of the model and the actual situation. In this case, the stand-alone device model needs to be modified and improved mainly around the model topology, parameter configuration, and model granularity until the stand-alone device model meets the requirements.

[0043] At step 105 , based on the stand-alone device model and according to the topology of the asynchronous motor direct torque control system, the system model is constructed using Modelica. The system model is formed by combining and connecting the stand-alone device models.

[0044] Specifically, refer to Figure 4 ,According to the topological structure of the asynchronous motor control system and the ,motor body parameters, the single-machine equipment models can be quickly ,combined and connected to establish a practical asynchronous motor direct torque ,control system model.

[0045] In some embodiments, after constructing the system model, it also includes: simulating and verifying the system model, and judging whether the simulation results are consistent with the expected theoretical results by comparison; if the simulation results are inconsistent with the expected theoretical results, adjusting the system model until the simulation results are consistent with the expected theoretical results.

[0046] In some embodiments, after constructing the system model, the method further includes: performing simulation analysis on the asynchronous motor direct torque system model according to task requirements, so as to obtain required information and knowledge.

[0047] Specifically, after the system model verification is completed, relevant simulation analysis can be carried out according to the task requirements of the asynchronous motor direct torque control system to obtain the required information and knowledge through the model.

[0048] In an embodiment of the present invention, the asynchronous motor direct torque control system modeling and simulation system is implemented based on the Modelica language and the MWorks platform, providing a series of functions including model development, management, compilation, solution and post-processing. MWorks is a system intelligent design and verification platform built by Suzhou Tongyuan Soft Control Information Technology Co., Ltd. based on the international knowledge unified expression and interconnection standards, and adopts a model-based approach to fully support system design. When solving, the order of solving the equations is determined according to the data flow environment of the equation system. The system compilation and solution process is as follows: Figure 5 As shown, it is roughly divided into three stages: compilation, analysis and optimization, and simulation solution. Among them, the solution order of the equation system is determined in the analysis and optimization and simulation solution stages. The compilation process includes grammatical semantic analysis and mathematical equation mapping. The former performs grammatical semantic analysis on the model code according to the Modelica language specification, and the latter completes the generation of the flattened hybrid equation system. After the compilation is completed, it enters the analysis and optimization stage, analyzes and optimizes the model equations, obtains a sequence of solvable equation subsets, and generates the corresponding model C code. Finally, with the help of the solver of the MWorks platform, a model simulation source code that can be compiled independently is constructed, and then a simulation program that can run the model is generated through the C compiler to determine the input and output variables and the order of solving the equations. The control effect of the system model is as follows. Figure 6 shown.

[0049] The present invention implements declarative modeling by constructing an asynchronous motor direct torque control system using the Modelica language. As a unified, multi-domain modeling language based on equations, object-oriented programming, and powerful component-based modeling capabilities, Modelica meets the needs of the development of modeling and simulation and is suitable for modeling and simulating various subsystem models, including mechanical, electrical, hydraulic, thermal, and control systems, as well as large-scale, complex physical systems. Furthermore, the Modelica model utilizes mathematical descriptions based on differentials, algebra, and discrete equations, offering universality, openness, and standardization. Furthermore, by combining declarative and object-oriented modeling, it offers excellent reusability, reconfigurability, and scalability. This reduces development difficulty, increases reusability, improves efficiency, and enables the system to reflect actual physical systems in the modeling of asynchronous motor direct torque control systems.

[0050] Those skilled in the art will appreciate that the embodiments of the present invention described above and shown in the accompanying drawings are intended to be illustrative only and are not intended to limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and illustrated in the embodiments. Any variations or modifications may be made to the embodiments of the present invention without departing from the principles described.

Claims

1. A method for constructing a direct torque control system of an asynchronous motor based on Modelica, characterized in that: The steps include: According to the physical characteristics and functions of the asynchronous motor direct torque control system structure, the asynchronous motor direct torque control system is decomposed into several general basic models, single machine equipment models and system models; Using Modelica to construct the universal basic model, the universal basic model is the universal minimum construction unit in the asynchronous motor direct torque control system; Using Modelica to build connectors, the connectors are used to realize information transmission between the universal basic models and between the universal basic model and external devices; Based on the universal basic model and the connector, the stand-alone device model is constructed using Modelica, wherein the stand-alone device model is formed by combining and connecting the universal basic models. The method for constructing the stand-alone device model includes: converting a physical model corresponding to the stand-alone device model into a mathematical model expressed in equations using Kirchhoff's laws, motor equivalent circuits, and / or control strategy theory; and converting the mathematical model into a Modelica model corresponding to the stand-alone device using a modeling software platform and Modelica; Performing simulation verification on the stand-alone device model, and determining whether the simulation results are consistent with the expected theoretical results by comparison; if the simulation results are inconsistent with the expected theoretical results, modifying the model topology, parameter configuration, and / or model granularity of the stand-alone device model until the simulation results are consistent with the expected theoretical results; Based on the stand-alone device model and according to the topological structure of the asynchronous motor direct torque control system, the system model is constructed using Modelica, wherein the system model is formed by combining and connecting the stand-alone device models; The system model is simulated and verified, and whether the simulation results are consistent with the expected theoretical results is determined by comparison; if the simulation results are inconsistent with the expected theoretical results, the system model is adjusted until the simulation results are consistent with the expected theoretical results.

2. The method for constructing a direct torque control system of an asynchronous motor based on Modelica according to claim 1, characterized in that: The method for constructing the asynchronous motor direct torque control system based on Modelica is implemented through the MWorks platform.

3. The method for constructing a direct torque control system of an asynchronous motor based on Modelica according to claim 1, characterized in that: After building the system model, it also includes: According to the task requirements, the asynchronous motor direct torque system model is simulated and analyzed to obtain the required information and knowledge.

4. The method for constructing a direct torque control system of an asynchronous motor based on Modelica according to claim 1, characterized in that: The universal basic model includes an interface model, a common component model and / or a stand-alone device component model; the connector includes an electrical connector, a mechanical connector, a thermal connector and / or a physical quantity interface connector; the stand-alone device model includes a motor controller, a speed regulator and / or a hysteresis controller; the system model includes a motor controller test model, a hysteresis controller test model and / or an asynchronous motor direct torque system model.

5. The method for constructing a direct torque control system of an asynchronous motor based on Modelica according to claim 4, characterized in that: The interface model includes a single-phase electrical interface, a three-phase electrical interface, a rotating mechanical interface and / or a physical quantity interface; the common component model includes an integration module, a diode, a grounding and / or a table lookup module; the stand-alone device component model includes a flux calculation module, a torque calculation module, a PWM generator, a regulator model, a hysteresis controller and / or a motor controller.

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