1. Servo Technology Servo systems are a crucial component of electromechanical products, and their control performance reflects the control quality of the equipment. The development of servo systems has evolved from hydraulic to electric, and electric servos have further progressed from analog to hybrid analog-digital and finally to fully digital servos. Based on the type of motor they drive, servo systems are divided into DC (DC) servo systems and AC (AC) servo systems. By the early 1990s, with the development of microprocessor technology, high-performance power semiconductor devices, and other manufacturing processes, as well as the increasing cost-effectiveness, AC servo technology gradually became the dominant product. AC servo systems are mainly classified into two categories based on the type of drive motor used: permanent magnet synchronous (SM type) motor AC servo systems and induction asynchronous (IM type) motor AC servo systems. Induction asynchronous motor AC servo systems, due to the robust structure, ease of manufacturing, and low cost of induction asynchronous motors, have a promising future and are one of the future directions of servo technology development. With increasingly fierce market competition, users are demanding higher technical standards and a more reasonable performance-price ratio for their products. Servo systems, with their outstanding performance, have transformed the processing procedures, manufacturing processes, and overall performance of products, and are now widely used in the industrial field. [IMG=Structure before modification (inverter)]/uploadpic/THESIS/2007/11/2007111615320636845U.jpg[/IMG] Figure 1: Structure before modification (inverter) [IMG=Structure after modification (Time Servo Controller)]/uploadpic/THESIS/2007/11/2007111615330221942M.jpg[/IMG] Figure 2: Structure after modification (Time Servo Controller) 2. Technological advancements lead to efficiency and savings Since 2003, Time Technology Co., Ltd. has launched its all-digital series of AC asynchronous servo controllers, which have been successfully applied to machine tools, oilfield machinery, elevators, and plastic machinery industries, bringing significant economic benefits to customers. During the product promotion process, we deeply realized that the fundamental source of enterprise efficiency improvement lies in the enhancement of the technological content of its own products. Shiguang Company's products possess the technological connotations of communication, digitalization, integration, and intelligence, improving the technological content of user products and significantly boosting customer product production efficiency, system transmission efficiency, and raw material utilization efficiency. This results in savings in product installation, debugging, and maintenance, as well as energy cost savings for end users. 3. Application in the Plastics Machinery Industry Screw extrusion machinery requires low-speed, high-torque output motor systems. However, the motor systems commonly used in screw extrusion machinery currently consist of a motor, frequency converter, and reduction gear, which suffer from low efficiency, small speed range, and high power consumption. Shiguang Technology Co., Ltd. has adopted servo control technology for AC asynchronous motors to modify the screw extrusion motor system of plastic blown film machines, compensating for the shortcomings of frequency converters in low-speed performance, and providing an innovative approach and solution for the upgrading of such machinery. 3.1 Structure of the screw extrusion motor system The time servo motor system replaces the original motor and frequency converter with a low-speed, high-torque motor and time servo controller, eliminating the reducer in the original transmission mechanism and simplifying the mechanical structure of the system. 3.1.1 Structure before modification (frequency converter), as shown in Figure 1 3.1.2 Structure after modification (time servo controller), as shown in Figure 2 3.1.3 Application examples ① Modification case 1 (as shown in Table 1) ② Modification case 2 (as shown in Table 2) [IMG=Modification case 1]/uploadpic/THESIS/2007/11/2007111615360429519R.jpg[/IMG] Table 1 [IMG=Modification case 2]/uploadpic/THESIS/2007/11/2007111615362294041Q.jpg[/IMG] Table 2 3.2 Technical innovation points (1) The spindle speed of the plastic screw extrusion machine is relatively low, generally around 0 to 160 rpm. Using a regular motor requires a reduction gear mechanism of 1:10 or higher. The low-speed, high-torque motor specially developed by Shiguang Company adopts the method of increasing the number of motor poles and reducing the motor base frequency to reduce the rated speed of the motor to below 200 rpm, while the output torque of the motor is greatly increased, so the speed reducer can be reduced or eliminated. To prevent motor damage due to failure and stall, a first-stage belt or chain drive is retained. (2) The speed regulation of the frequency converter is at the highest point of efficiency and output torque at the motor base frequency. According to its characteristic curve, the output torque and efficiency decrease below the base frequency. Therefore, in order to ensure sufficient output torque at low speed, the motor power must be increased. However, the Shiguang servo controller maintains constant torque output below the motor base frequency and has an overload capacity of more than three times the rated torque. Therefore, Shiguang's servo control system can ensure that the output torque is not less than the rated torque from the lower rated speed to zero speed. According to the torque reduction curve of the motor when the frequency converter controls the low speed, the servo controller can reduce the motor power to 1/2 to 2/5 of the frequency converter control. (3) If the frequency converter is used to drive the low-speed, high-torque motor, due to its small speed range and insufficient low-speed torque, the working state is poor at low frequency. At frequencies below 8Hz, the torque is significantly insufficient. The time servo controller has a speed range of 0-400Hz and good low-frequency torque characteristics, which can control the motor smoothly and accurately at low speeds. For equipment such as blown film machines that have strict requirements on film thickness, it can accurately control the motor, which has a great technical advantage compared with frequency converters. 3.3 Economic and social benefit analysis (1) Through extensive comparison, the cost of the time servo control system is basically the same as or slightly higher than the cost of the system it replaces. (2) Due to the elimination of the reducer, steel materials are saved, casting and machining processes are reduced, installation and commissioning processes are simplified, and maintenance costs of machinery are reduced. (3) Energy is saved, with a power saving rate of 30-40%, and the cost of electricity saved is very attractive to the end users of the product. According to the above transformation case, the motor power is reduced by 7.5kw, and the power consumption is reduced by 5kw. The electricity consumption is 5 kWh per hour, and the electricity saving is 120 kWh per day (this type of machinery requires a preheating process, so continuous production is the most economical). Based on an industrial electricity price of 0.75 yuan/kWh, the daily electricity saving is 90 yuan; based on 25 days per month, the monthly electricity saving is 2250 yuan. The monthly electricity saving is enough to fully recover the increased cost of the servo-controlled motor system, and the subsequent electricity saving can greatly reduce the user's production cost. 3.4 Conclusion (1) The motor power is reduced, the energy saving effect is obvious, and the user's operating cost is reduced. (2) The mechanical structure is simplified, saving metal materials; the operation is simplified, reducing maintenance costs. (3) The control range is increased, the control accuracy is improved, and the control motor efficiency is improved. (4) It improves the user's product quality and enhances the product grade of plastic extrusion machinery. Proceedings of the Second Servo and Motion Control Forum Proceedings of the Third Servo and Motion Control Forum