0 Introduction Winding machines are specialized equipment in the textile industry, categorized into inverted-bottle and rack-type inverted-bottle machines. Different types of yarn require different winding tensions during winding, resulting in tight or loose bobbins. If a fixed-frequency motor is used to drive the bobbin winding, the motor speed remains constant. As the bobbin diameter increases and the linear speed rises, the wound bobbin will be loose inside and tight outside, failing to produce an ideal bobbin. Using a general frequency converter makes it difficult to control the output frequency according to the spinning linear speed requirements, and it's also difficult to provide adequate protection against yarn breakage and power failure. Specialized winding machines overcome these shortcomings, allowing for customized control based on the user's control method, making them convenient and efficient for users. 1 Product Introduction The LT2000 is a specialized frequency converter developed by our company for the rack-type winding industry. This product uses a dedicated motor control chip, features a modular design, complies with electromagnetic compatibility standards, and is developed using advanced production processes and a human-centered management philosophy. This product is suitable for industries such as knitting, silk weaving, yarn making, dyeing, and chemical fiber manufacturing. 2. Product Functions : The LT2000 provides users with the following functions: constant linear speed control, decreasing speed control, frequency oscillation speed control, and frequency increasing speed control. Three tension adjustment controls are available for users to choose from: automatic stop upon yarn breakage, and free stop due to poor contact between the pressure roller and the yarn bobbin during PI adjustment. During operation, the current spinning length, set spinning length, and current operating frequency can be displayed cyclically. Spindles produced using this product have an attractive appearance and large winding capacity, suitable for both loose and tight bobbin production. 3. Application Analysis under Constant Linear Speed : To better control spinning speed and ensure a beautiful spindle and accurate yarn length, the quality of contact between the yarn bobbin and the pressure roller reflects the accuracy of the linear speed. Under constant linear speed control, if a yarn breakage or power failure occurs, the current yarn length and current operating frequency will be automatically recorded. The next run will operate according to these parameters, but a delay before starting PI adjustment is necessary. When using a straight yarn bobbin, the contact between the bobbin and the pressure roller is generally good, resulting in even stress on the spun yarn and a more aesthetically pleasing bobbin. However, when using a tapered yarn bobbin, the following situation may occur, which we will focus on below. 3.1 Good Contact Between the Yarn Bobbin and the Pressure Roller As shown in Figure A, when the contact between the yarn bobbin and the pressure roller is good, the linear speed of the pressure roller can better reflect the average linear speed of the yarn bobbin. At this time, when the motor starts running, the linear speed of the yarn bobbin is basically the linear speed we set at the beginning of operation. When adjusting Pl, it will oscillate back and forth around this target linear speed. The yarn spun in this way will be of good quality, and the machine will run normally. 3.2 Contact between the smaller diameter end of the yarn bobbin and the pressure roller As shown in Figure B, when the yarn bobbin contacts the smaller diameter end of the pressure roller, the actual linear speed displayed before PI adjustment may sometimes be lower than the target linear speed we set. When this speed is too low, the contact between the pressure roller and the yarn bobbin will be poor, and the linear speed reflected by the pressure roller will not truly reflect the actual linear speed. Therefore, we require the machine to stop and display Err2. At this time, the user needs to adjust the contact between the pressure roller and the yarn bobbin so that the linear speed of the pressure roller can reflect the actual linear speed. If the user adjusts it improperly, the frequency converter will increase the frequency to increase the linear speed. This may result in the frequency converter rising to a very high level, causing the machine to run very fast, which may damage the mechanical components. 3.3 Contact between the larger diameter end of the yarn bobbin and the pressure roller As shown in Figure C, when the larger diameter end of the yarn bobbin and the pressure roller contacts, the actual linear speed displayed before PI adjustment may be higher than the target linear speed set. In this case, this higher linear speed does not reflect the true linear speed, and the frequency converter will automatically reduce its frequency to lower the current speed. However, as the yarn bobbin increases in size, the contact between the pressure roller and the yarn bobbin will gradually improve, and the displayed speed will reflect the true linear speed. At this point, if the frequency converter drops too low, the actual speed will be significantly lower than the set speed, causing the frequency converter to automatically stop and display Err2. Therefore, users should adjust the contact between the yarn bobbin and the pressure roller in this situation. 4. Improved Constant Linear Speed ​​PI Adjustment When using constant linear speed PI adjustment, it is recommended that users do not set the linear speed too high to avoid damaging the machinery due to excessive motor speed, resulting in losses. Pay close attention to the parameter settings in the constant linear speed function area. The pressure roller must be set to the actual value, and the yarn bobbin diameter (when the spindle is empty) must also be set to the actual value. However, when the motor's rated speed is not 1500 rpm, the yarn bobbin diameter setting must be adjusted according to the actual linear speed. This ensures that the actual displayed linear speed at the start of PI adjustment is close to the set linear speed value. If the actual linear speed at the start of PI adjustment is too high or too low relative to the set linear speed, it will affect the spinning effect and may even trigger the Err2 protection. To better facilitate user experience with PI adjustment, two function codes, 4-10 and 4-11, have been added to the existing functionality. These represent the delay time before PI adjustment begins and the set value when the displayed speed is lower than the target linear speed, respectively. If the user finds that the displayed current speed does not accurately reflect the actual linear speed, they can appropriately increase the delay time before PI adjustment or increase the setting value of 4-11 to allow the machine to adjust gradually without stopping. The maximum frequency of PI adjustment increases is limited at a constant linear speed. The frequency algorithm corresponding to the target linear speed is also specified. Based on the correspondence between asynchronous motor speed and frequency: generally calculated at a motor speed of 1500 rpm under industrial frequency, 1 Hz corresponds to a motor speed of 30 rpm. The starting frequency = target linear speed x 1000 / yarn bobbin diameter / 30 / 314. When the yarn bobbin and pressure roller have good contact, the displayed linear speed can accurately reflect the actual linear speed. At this time, the spinning effect is better and more stable, which will not be discussed in detail here. When the pressure roller and the end of the yarn bobbin with a diameter smaller than 1000 Hz are in contact, as mentioned earlier, the displayed linear speed is lower than the actual linear speed. When PI adjustment starts, it will assume this speed is the actual speed and increase the frequency of the inverter to raise the linear speed to the target value. At this time, the machine will have a high speed, which can sometimes be unbearable. Now, users can increase the delay time for starting PI adjustment by 4 to 10 seconds to allow the yarn bobbin to wind fully, so that the pressure roller can truly reflect the actual linear speed. Of course, by limiting the maximum frequency of PI adjustment, the machine speed will not reach a very high state. If the displayed linear speed is too low and you don't want the machine to stop, you can appropriately increase the setting value by 4-11 to allow the PI adjustment to gradually reach the desired target linear speed. Of course, during machine operation, users should pay attention to the contact between the pressure roller and the yarn bobbin, ensuring a uniform contact surface. When the pressure roller contacts the larger diameter end of the yarn bobbin, the displayed linear speed will be significantly higher than the target linear speed. Users don't need to worry about such a high linear speed causing mechanical damage, as this linear speed is inaccurate and doesn't accurately reflect the actual linear speed. If the machine stops due to the low speed when it's time for PI adjustment, users can increase the value by 4-10 to allow the yarn bobbin to wind fully. Once the contact between the pressure roller and the yarn bobbin is uniform, PI adjustment will begin, preventing machine stoppage. For specific use, users should provide detailed training to operators, strictly adhering to the normal operating procedures. Incorrect operation will not only affect the machine's lifespan but also negatively impact the frequency converter. For example, if you change the yarn bobbin before it's fully spun, the length should be reset to zero. This is because the inverter records the parameters from when the bobbin last stopped, and these cannot be used now. Otherwise, the machine will frequently stop or the machine speed will suddenly increase. Please pay attention to the operating procedures. [align=center][b]For more details, please click: Application of Huifeng Winding Machine Dedicated Inverter in Constant Linear Speed ​​Mode[/b][/align]