Xiao Yinghui, School of Mechanical and Electrical Engineering, Shandong University of Science and Technology; Ren Huiying, Machinery Manufacturing Plant, Shandong Yankuang Group; Sun Dong, Fourth Engineering Department, Zhongxing Construction and Installation Company, Shandong Zaozhuang Mining Group. This paper uses the simulation tool under Matlab to conduct simulation research on vector control of asynchronous motors. A simulation model of the motor is constructed by transforming the vector control equation of the asynchronous motor, and a voltage converter is constructed by transforming the voltage equation of the asynchronous motor. Furthermore, a model of a voltage-type asynchronous motor speed control system is constructed and simulated. Simulation results and explanations are given. 1 Introduction With the development of variable frequency speed control technology, vector control technology, and direct torque control technology, research on AC drives has become increasingly in-depth. Currently, there are two types of variable frequency power supplies: AC-DC-AC and AC-AC. The former has relatively good output characteristics, but due to large harmonic components, it is prone to current pollution and it is difficult to achieve bidirectional power flow. AC-AC converters use thyristor-shift trigger control, resulting in severe distortion of input voltage and current, low power factor, and high harmonic suppression costs, making large-scale application difficult. This paper utilizes computer-aided design tools and employs simulation to conduct preliminary experiments. Simulation is a crucial tool in system design, providing guidance for the overall design process. Popular software such as PSPICE, ICAPS, and MATLAB/SIMULINK each have their strengths, with MATLAB/SIMULINK being particularly favored by researchers due to its wide application and flexibility. Servo control technology for AC motors is a current research focus, using asynchronous motors as the controlled object, making simulation studies of its control systems extremely important. This paper uses MATLAB's SIMULINK tool to simulate a voltage-type servo control system for an AC motor and analyzes the simulation results. 2. Introduction to MATLAB/SIMULINK Software MATLAB/SIMULINK from Matworks is a visualization software package used for modeling, simulating, and analyzing dynamic systems. Users can quickly build various continuous, discrete, or hybrid linear and nonlinear systems, performing functions such as engineering calculations, algorithm research, modeling and simulation, data analysis and visualization, and engineering drawing. During simulation, users can intuitively observe dynamic changes at various points in the system and conveniently perform time-domain and frequency-domain analysis of the simulation results. The MATLAB 6.5 system used by the author includes various power device models, such as voltage/current sources, transformers, power electronics modules, various AC motor models, and connector measurement modules. Therefore, it is very convenient to build a power system model. PSB (Electrical System Module Library) is a dedicated visual modeling and simulation tool for electrical systems, using the SIMULINK environment. The electrical components used in the simulation interact with this model library, allowing power system modeling and analysis to utilize software toolboxes from mechanical, thermal, control, and other disciplines. The latest version of MATLAB 7.0 provides the Embedded Target TI C2000 DSP Toolbox, which can directly integrate algorithms developed in SIMULINK and MATLAB with the TI eXpresDSP tools and C2000 DSP processor, enabling automatic code generation, rapid prototyping, and embedded system development. 3. Establishment of the Vector Transformation Model of the AC Motor The mathematical model of an AC asynchronous motor is a high-order, nonlinear, strongly coupled, multivariable system. Therefore, the following assumptions are usually made in the study: (1) Spatial harmonics are ignored, the three-phase windings are assumed to be symmetrical, and the generated magnetomotive force is distributed along the air gap circumference according to the sinusoidal law; (2) Core loss is ignored; (3) Magnetic circuit saturation is ignored, that is, the self-inductance and mutual inductance of each winding are constant; (4) The influence of frequency and temperature changes on winding resistance is not considered. Under the above assumptions, the vector control model of the AC motor is established as an equation on the synchronous coordinate system MT coordinate system with the same speed as the motor magnetic field. The MT axis is oriented with the direction of rotor flux linkage and the stator current is orthogonally decomposed, thus providing conditions for controlling torque and magnetic flux respectively. The transformation matrix of the asynchronous motor from the stationary coordinate system (a,b,c) to the two-phase synchronous rotating coordinate system (d,q) is: ωs-synchronous rotational angular velocity; θ(0)-arbitrary initial angle. From the coordinate transformation, the voltage equation of the asynchronous motor in the two-phase synchronous rotating coordinate system (d, q) can be obtained as follows: Where: Uds, Uqs: d-axis and q-axis of stator voltage; ids, iqs: d-axis and q-axis of stator current; idr, iqr: d-axis and q-axis of rotor current; Rs: stator resistance; Rr: rotor resistance; Ls: self-inductance of stator winding; Lm: mutual inductance between stator and rotor; Δω: slip angular frequency of asynchronous motor; P: differential operator. (2) Basic structure There are three ways to select the magnetic field orientation axis of the vector control system: rotor magnetic field orientation, air gap magnetic field orientation and stator magnetic field orientation. The control equation of the vector control system with rotor magnetic field orientation is: Where Tr=Lr/Rr is the rotor excitation time constant; CIM=np＊Lm/Lf is the torque coefficient; np is the number of pole pairs of the motor. Through the above coordinate transformation and rotor magnetic field orientation, the equivalent DC motor model of the three-phase asynchronous motor in the synchronous rotating coordinate system can be obtained. According to the speed control principle of the DC speed regulation system, the basic structural block diagram of the three-phase asynchronous motor vector control system is shown in Figure 1. [IMG=Figure 1 Vector Control System Structural Block Diagram]/uploadpic/THESIS/2007/11/20071116140249450518.jpg[/IMG] Figure 1 Vector Control System Structural Block Diagram 4. Establishment of the Simulation System The position following system diagram of voltage vector control is shown in Figure 2. [IMG=Figure 2 Voltage Control Position Following Diagram]/uploadpic/THESIS/2007/11/20071116140321114984.jpg[/IMG] Figure 2 Voltage Control Position Following Diagram Converting the system diagram into a simulation model under SIMULINK, and using the motor model and voltage converter model introduced above, the complete control system model is established. 5. Results Analysis The main motor parameters in the simulation system given above are as follows: power 2.3kW, frequency 50Hz, rated voltage 380V, stator resistance 2.23Ω, rotor resistance 2.65Ω, stator and rotor self-inductance coefficients are both 0.0186H, mutual inductance coefficient is 0.3428, and number of pole pairs is 2. With speed as the given signal, the motor is subjected to a rated load of 8.9 Nm. The speed, torque and current are simulated. The simulation results are as follows: (1) Speed ​​simulation curve (Figure 3) [IMG=Figure 3]/uploadpic/THESIS/2007/11/2007111613562331778R.jpg[/IMG] Figure 3 (2) Torque simulation curve (Figure 4) [IMG=Figure 4]/uploadpic/THESIS/2007/11/2007111613482764146S.jpg[/IMG] Figure 4 (3) Current simulation curve (Figure 5) [IMG=Figure 5]/uploadpic/THESIS/2007/11/2007111613564534750S.jpg[/IMG] Figure 5 Our analysis shows that under rated load, the speed can reach a stable state within 1 second, with a maximum overshoot of less than 4%; the torque reaches a steady state within 200 ms, with the maximum electromagnetic torque being approximately 5 times the rated torque; and the steady-state value of the current is basically the same as the rated value. 6. Conclusion Based on a detailed introduction to the MATLAB/SIMULINK simulation tools, we implemented a speed regulation experiment of the vector control system for an asynchronous motor, analyzed the advantages and disadvantages of the model, and established a simulation model of the vector control system using the PBS module, realizing the analysis and calculation of the simulation results. The model established using this system is intuitive and easy to implement, requiring no programming, providing a good design environment for efficient and successful design and verification of design ideas. Engineering technicians can use it for simulation research to enhance their understanding of the system. (Proceedings of the 2nd Servo and Motion Control Forum, Proceedings of the 3rd Servo and Motion Control Forum)