1 Introduction High dynamic response speed control system is based on ensuring stable output speed and fast response speed given value. The system can stably and quickly follow load changes and recover quickly from the transient speed caused by sudden external disturbances such as load changes. In the past, DC speed control system was mainly used to achieve this. Considering the power and maintenance of DC speed control system, vector frequency conversion control technology was used to control asynchronous motor to achieve high dynamic response speed control system. The dynamic mathematical model of asynchronous motor is a high-order, nonlinear, strongly coupled multivariable system. The control torque law of DC motor can be simulated on three-phase AC motor through coordinate transformation [1]. Vector control is based on rotating magnetic field and establishes equivalent relationship between three-phase AC winding current, two sets of AC winding current and orthogonal winding DC current on rotating coordinate to achieve decoupling of stator current and reduction and linearization of system order. 2. Control Strategy The open-loop slip vector control system employs open-loop flux linkage control to avoid the impact of inaccurate rotor flux linkage feedback signals on control accuracy. Magnetic field orientation is determined by the flux linkage and torque command signals, without actually calculating the rotor flux linkage and phase. Instead, it indirectly orients the magnetic field through parameter identification and adaptive control, while speed control remains closed-loop. This approach inherits the advantages of slip frequency control systems based on the steady-state model of asynchronous motors and utilizes the vector control laws based on the dynamic model of asynchronous motors. It significantly improves dynamic performance while maintaining good stability. Many frequency converters now perform well in parameter identification and adaptive control. By selecting the appropriate type and controlling a high-performance asynchronous motor, a high-dynamic speed regulation system can be achieved through parameter settings. The control system block diagram is shown in Figure 1. [align=center]Figure 1. Magnetic flux open-loop slip vector control system[/align] Based on this concept, a vector control speed regulation system was designed using a Siemens 6SE70 frequency converter to control a 60kW 1PH7 series asynchronous motor. Under no-load conditions, it achieves a dynamic response requirement of no more than 200ms for a 10% speed step response time, and during the transition process, the system exhibits no oscillation and an overshoot of no more than 2%. 3. System Composition The entire speed regulation system consists of a 75kW 6SE7031-5EF60 frequency converter, plus necessary peripheral hardware, enabling local and remote start, stop, setpoint, and monitoring functions. The system uses appropriate braking units and braking resistors to dissipate the energy fed back by the motor during deceleration braking, improving the dynamic performance of the deceleration process. The asynchronous motor model is 1ph7184-2hf300bc0, 60kW. Its main parameters are: rated speed 1750r/min, maximum speed 5000r/min, base frequency 59.0Hz, rated current 120.0A, rated voltage 388V, torque 327N.m, and power coefficient cosφ=0.78. The motor comes with a built-in cooling fan, speed encoder (1024), and temperature sensor. The system principle block diagram is shown in Figure 2. [align=center] Figure 2 System Principle Block Diagram[/align] 4 System Debugging Before debugging, an electrical check was performed on the entire system to ensure that all electrical wiring connections were correct and reliable, and that all thermal overload protections were properly set. Then, power was applied to confirm that the main circuit and auxiliary control circuit were in normal condition, and that the cooling fan rotated in the correct direction. First, simple parameter settings are performed to initially check that the entire system can work normally. Then, expert application parameter settings are performed. This process involves setting up basic functions and inputting motor parameters into the frequency converter, which then performs self-tuning to obtain the motor parameters. Parameter settings are performed according to the 6SE7031-5EF60 manual, combining the frequency converter's internal free function modules to achieve functions such as computer/manual analog input and selection, step input, and analog output of input and feedback quantities. Dynamic response parameter adjustment follows the principle of ensuring the system's mechanical characteristics and obtaining the minimum dynamic response time. For flux regulators, self-tuning values ​​are generally adopted to prevent inappropriate modifications from affecting the flux input. The main adjustments are to the proportional gain kp and integral time of the speed regulator; the speed regulator's parameters are automatically written during the self-tuning process. For this system, after self-tuning, the system is self-protected. A 0.5s ramp function is added to the rise and fall signals, and the initial and final arc times are both 10s. At this time, kp=7.2, and the integral time is 400ms. Under these conditions, the system's dynamic response time is about 450ms, with no overshoot and stable operation. However, this is far from meeting the requirements for high dynamic response performance. To pursue faster speed, the ramp function is removed, and the ramp function time is set to 0. The initial and final arc times are set to 10ms for protection. Then, the proportional gain kp and integral time of the speed regulator are adjusted. The speed regulator is a PI regulator. When the integral time is constant, increasing the proportional gain kp speeds up the dynamic response time, but also increases the overshoot. When the proportional gain kp is constant, increasing the integral time lengthens the dynamic response time, suppresses the overshoot to some extent, and improves the stability of the transient process. Decreasing the integral time shortens the dynamic response time, worsens the stability of the transient process, and does not suppress the overshoot. Therefore, the proportional gain kp and integral time need to be continuously compared and adjusted to obtain the optimal parameters that match the system. The parameters are adjusted as follows: p462=0; // Cancel the ramp function // p463=0; // Acceleration time unit: s // p464=0; // Cancel the ramp function // p465=0; // Deceleration time unit: s // p469=0.01; // Initial arc time of the given ramp function // p470=0.01; // End arc time of the given ramp function // p235=7.2; // Gain kp of the speed regulator // p240=250; // Integral time of the speed regulator // These parameter adjustments are closely related to the performance of the frequency converter and the motor. Continuous trial and error is necessary to measure the dynamic performance of the system under different parameters and ultimately select the optimal parameters. During actual debugging, when measuring the feedback signal at the analog output terminal with an oscilloscope, it was found that after using the divider function, the analog output became a discontinuous value that changed only once every 76ms. After inspection and verification, it was found that this was due to the sampling time setting of the Siemens inverter's internal free function module being too high. Lowering it made the output waveform continuous. However, to meet real-time dynamic measurement requirements, the use of free function modules in the output channel should be reduced. 5 System Braking When the speed control system is decelerating, the motor is in a generating state. The inverter rectifies the generated AC power into DC power and stores it in a capacitor. When the DC bus voltage exceeds the shutdown threshold, the inverter will automatically shut down. Therefore, it is necessary to reasonably select the braking unit and braking resistor to effectively dissipate the energy on the DC bus. For speed control systems with high dynamic response, during rapid braking, the braking unit must open the IGBT within a short time (a few ms to tens of ms) so that the braking resistor can dissipate the energy generated by the motor, while also meeting the requirements for repeated braking. Therefore, it is necessary to estimate the energy generated during braking and calculate the braking unit and braking resistor accordingly. Based on the calculation method given by Yaskawa inverter [6][7], after modification, a calculation formula that meets the requirements of high dynamic response speed regulation system is obtained. Maximum braking torque mbmax ​​mbmax=2mrmot (1) Where: mrmot——motor rated torque Maximum braking power pbmax pbmax =mbmax(n1-n2)/9.55 (2) Where: n1——speed before braking; n2——speed after braking Electrical braking power pe1 pe1 =ηgear pbmax-k prmot (3) Where: ηgear——mechanical efficiency; prmot——motor rated power; k——motor internal loss prediction coefficient (see attached table) It is generally believed that mechanical loss can be ignored, and ηgear equals 1, so that the electrical braking power has a margin. [img=195,148]http://www.ca800.com/uploadfile/maga/inv2008-3/zxb1.jpg[/img] Braking resistance value rb rb≤ub2/ pe1 （4） Where: ub——braking unit IGBT chopper voltage. The inverter's shutdown threshold for this system is 820V, and the IGBT chopper voltage of the braking unit is set to 730V. Following the calculation formula above, substituting the motor parameters, the calculation process is as follows: Maximum braking torque mbmax ​​= 2mrmot = 2 × 327 = 654 (N·m) Maximum braking power pbmax = mbmax(n1-n2)/9.55 = 654 × 5000/9.55 = 342400 (W) Electrical braking power pe1 = ηgear pbmax - kprmot = 34240 - 0.05 × 60000 = 312400 (W) Braking resistance value rb ≤ ub2/pe1 = 7302/312400 = 1.7058 (ω) Since the maximum values ​​are used throughout the calculation, based on the actual product conditions, the braking unit is set to 300kW and the braking resistor to 2Ω. Verification has shown that this meets the requirements for rapid braking, and the inverter will not experience overvoltage or overcurrent faults, nor will the system exhibit braking shock. [font=黑体][color=#008284]6 Dynamic Performance[/color][/font] Under no-load conditions, the speed command signal jumps from 4000r/min to 4500r/min in a step. The actual speed change transition time is 172ms, the overshoot during the transition is 2%, and there is no oscillation; the waveform is shown in Figure 3. [align=center][img=560,418]http://www.ca800.com/uploadfile/maga/inv2008-3/zx03.jpg[/img] Figure 3. Input and feedback curves during the step speed increase process[/align] Under no-load conditions, the input speed signal drops from 4500 r/min to 4000 r/min in a step. The actual speed change transition time is 144 ms. There is no overshoot or oscillation during the transition process; the waveform is shown in Figure 4. [align=center][img=550,409]http://www.ca800.com/uploadfile/maga/inv2008-3/zx04.jpg[/img] Figure 4. Feedback curves of the step speed decrease process[/align] From the system's rising and falling step speed processes, it can be seen that the system's dynamic response is very fast, and there is no oscillation or large overshoot. A slight overshoot occurs when the speed increases, which is suppressed by the load's damping effect when running under load. The speed decrease process is a braking process. At this time, the braking unit and braking resistor work, making the speed change transition smoothly. Multiple step speed reductions were attempted in a short period of time, and the system braking was normal, the operation was stable, and no faults such as overvoltage or overcurrent occurred. 7 Conclusion This paper mainly explores the application of a high dynamic response vector frequency conversion speed control system. Through the design and debugging of the actual system, a high dynamic response speed control system that operates stably under no-load conditions was obtained. The parameter settings of the speed regulator and the selection of the braking unit and braking resistor are the key to the system's realization. In the future, the optimization design of the system should focus on the following points: (1) Conduct simulation analysis on the speed regulator to obtain more accurate parameters for setting, reduce the debugging time of repeated trial and error, increase the research on the flux regulator, and explore the influence of flux on the dynamic performance of the system. (2) Increase the margin of the frequency converter, select a high-power frequency converter to drive the motor, and try to reach 2 to 2.5 times the rated power of the motor. Braking can also adopt the braking method of feedback to the grid. (3) The selection of the motor should also be evaluated. The fast response performance and mechanical characteristics of the asynchronous motor should be studied to ensure that the motor can meet the requirements of high dynamic response performance.