Abstract: Analysis of the application of Mingdian frequency converters in the electrical control system of roving frames in the textile industry. [align=left] Keywords: Frequency converter 1 Introduction The roving frame is an indispensable process in the spinning system. Significant progress has been made both domestically and internationally in the technological advancements of roving frame spinning performance, especially in the late 20th century. Due to the application of electronic computer technology, sensor technology, and particularly frequency conversion speed control technology in roving frames, as well as continuous improvements in spinning technologies such as drafting, pressurization, and winding, modern roving frames have developed into high-speed, high-quality, high-yield, and high-efficiency modern roving frames. With the continuous innovation of new frequency converters and the rapid development of frequency conversion speed control technology, excellent conditions have been provided to meet the load characteristics and process requirements of roving frames. The ideal control function of frequency converters, combined with the cooperation of computers, has simplified the mechanical structure of roving frames, providing conditions for multi-motor control and paving the way for high-speed and mechatronic roving frames. 2. Introduction to Roving Frames and Related Functional Requirements Runfa Group's textile branch has imported 30 TJFA458A roving frames manufactured by Tianjin Textile Machinery Factory. This model is widely recognized for its superior performance both domestically and internationally. It boasts unique advantages in operational functionality, integrating advanced technologies such as programmable control, AC frequency conversion speed regulation, and servo tracking control. Since its introduction, the electrical control system has operated smoothly with a low failure rate and is easy to maintain. The electrical control system consists of a PLC programmable controller, frequency converter, commutation control, electromagnetic clutch, and infrared photoelectric detector. This control system is connected via cables for communication, controlling the commutation, operation, and doffing of the equipment to complete the machine's normal operating procedures. The main unit uses a Japanese Meiden frequency converter, featuring operation display, frequency modification, function code viewing, function code reset, function code setting, and fault display functions. Based on this high performance, the new TJFA458A roving frame has been continuously improved, establishing a solid leading position in the domestic market. In particular, the application of high-quality Meiden frequency converters on this model has achieved the goal of improving roving quality and reducing the cost per spindle. This model adopts a new type of enclosed high-speed spindle, an electromechanical integrated forming structure, and is controlled by a programmable logic controller (PLC) and frequency converter. It features slow start, automatic full-yarn control, and achieves fixed-length, fixed-position, and directional stopping. It has a PV4 LCD display, strong adaptability to various yarn types, and is suitable for spinning pure cotton, pure polyester, pure viscose, and their blends. Fiber length is 22-65 mm. It has low rated power, with the main motor at 8.6 kW and the entire machine at 14.2 kW (including the circulating cleaner). This is the lowest among similar products. The transmission is smooth, and the machine vibration is low. The specific process parameters for this model are shown in Table 1. [/align][align=center] Table 1 TJFA458A Roving Frame Process Parameters Table [/align][align=left][b]3 Effects of Using Meiden Frequency Conversion Speed ​​Control System on the Roving Frame[/b] After the Meiden frequency converter was used on this model of roving frame, it became an ideal slow-start device. In many traditional slow-start devices, whether hydraulic, clutch friction plate type, single-phase reactor type, or bidirectional thyristor type, the motor starts under the condition of rated voltage 380V and standard frequency 50 Hz. The powerful starting torque relies on these devices to soften, absorb, and cancel it out. Each of these methods comes at a cost: not only is it adding a device and increasing costs, but more importantly, it brings negative effects such as overheating and related hazards. The principle of a frequency converter is not softening, absorbing, or canceling out torque, but rather it achieves this through its own settings. For example, if we set the starting frequency of the frequency converter to 1Hz, according to the U/F curve of the frequency converter, the starting voltage is only 7.6V. If we then set the starting time, such as 15 seconds, the roving frame will start from 1Hz, with the voltage starting at 7.6V. Within 15 seconds, the frequency increases from 1Hz to 50Hz, and the voltage increases from 7.6V to 380V. It's easy to imagine that the start-up is smooth; the initial shock of starting is practically nonexistent. Undoubtedly, the minor damage and breakage caused by starting up will be minimized. Mingdian frequency converters, when used on roving frames, can also achieve positioning and stopping. There are three types of stopping during the spinning process: photoelectric yarn breakage stopping, full yarn stopping, and manual stopping. Regardless of the type of stopping, the following procedure will be followed: within the set stopping time (e.g., 12 seconds), the frequency will decrease from 50Hz to 3Hz-3Hz, reducing the roving frame speed to a crawling speed. The frame will only stop after the set position is reached and a signal from the positioning sensor is emitted. This fully utilizes the frequency converter's capabilities: firstly, low-speed positioning is easy and accurate, facilitating rejoining operations for the operator; secondly, low-speed stopping prevents and reduces the occurrence of problems caused by high-speed stopping. Changing the frame speed is easy and quick, requiring only button settings on the frequency converter's operation panel, facilitating the monitoring of process parameters and other parameters (such as operating frequency, spindle speed, and motor current), thus simplifying management. The energy-saving effect of using Mingdian frequency converters on roving frames is also very obvious, most notably in the significant reduction of motor temperature rise. Under long-term operation, its surface temperature is only comparable to human body temperature. Generally, the starting current of the motor controlled by the frequency converter does not exceed 1.5 times the rated current. It is generally said that frequency converters can save 10%-30% of electricity in production. Further confirmation is required after installation and use on the roving frame. After using Mingdian frequency converters on the roving frame, mechanical and electrical failures are significantly reduced. This has been proven both theoretically and practically. The former is due to the smooth starting and braking, with almost no impact, less gear wear and loosening of the set wire. In addition, due to the spindle positioning stop, the inching operation by the operator is also reduced. Even when inching is used, there is no impact. The reduction in electrical failures is even more significant because the contactors and relays with contacts that were prone to failure in the past have been replaced by frequency converters, and the failure rate of the frequency converter itself is extremely low. Figure 1 is a block diagram of the entire control system. Figure 1 System Control Block Diagram 4. Specific Applications and Parameter Settings of Meidensha Inverters In 2000, Meidensha Corporation of Japan launched the VT230S series inverters (0.4-660kW) with vector control technology. Perfect vector control technology, current tracking control technology, and flux compensation function ensure the inverter's output torque. Slip compensation reduces speed fluctuations caused by load changes. Motor adaptive function and automatic motor parameter tuning integrate the inverter with the motor. It has a wide power range: 0.4～660kW/400V series, a wide speed range: 0.1～440Hz, and an extended acceleration/deceleration time: 0.01～60,000 seconds. It features parameter copy/comparison function, a built-in PID controller, a built-in multi-pump controller, and a built-in programmable controller. It also features a patented PWM soft-sound tuning, making it a completely environmentally friendly product. Moreover, it is multi-functional: sensorless vector control, high-performance vector control with sensors, PM motor energy-saving drive, V/F constant torque control (maximum torque boost), and V/F variable torque control; the dynamic start function can automatically track the motor speed and start operation, and switching control is simple and easy. It is compatible with JIS, JEC, JEM, CE, UL and other standards and specifications, and is widely used in imported complete sets of equipment in China. A PROFIBUS interface has been added for easy network connection. It features a detachable operator, a remote control panel with digital knob function, and a quick-rotation menu. The operator uses a large shuttle knob for easier operation. The operator can be easily removed and placed outside the inverter with an extension cable. Another important point is its excellent energy-saving effect. Below is the wiring diagram and detailed parameter settings for this model of inverter applied to the roving frame control system. Figure 2. Circuit control diagram of frequency converter for roving frame [align=center] Table 2. Main parameter setting table of Mingdianshe frequency converter for roving frame[/align][b][align=left]5 Conclusion[/b] The use of high-performance frequency conversion speed regulation technology in roving frames has been widely recognized by textile mills in recent years. Especially for this series of suspended spindle roving frames, which features high speed, large package size, and stable operation, the performance advantages of the equipment will be better realized when combined with frequency converter control. This reduces failure rates and maintenance costs. Most modern roving frames have implemented frequency conversion speed regulation technology with computer control systems, thus simplifying the roving forming mechanism and simplifying the machine structure. The frequency converter motor operates under PLC control commands, fundamentally eliminating roving defects during start-up and shutdown, realizing roving winding tension adjustment, improving yarn quality, and significantly reducing defects. This also marks a significant step towards high-tech roving winding technology.[/align]