REPOSAL® machine research on tension control of transformer winding machine

In modern society, electricity is like a surging torrent, injecting strong impetus into our life and production. With the rapid development of China's science and technology and economy, the demand for electricity is increasing day by day, and the demand for transmission and distribution transformers, as an important cornerstone of the power system, is also rising.

The transformer is the "heart" of the power system, and the winding coil inside it is a key component of this "heart". The winding quality of the enameled wire and insulating tape in the winding coil directly determines the reliability of the transformer. The quality of this winding depends to a large extent on the performance of the transformer winding machine.

With the sharp rise in demand for transformers, the performance requirements for transformer winding machines are becoming more and more demanding. A high-performance transformer winding machine must not only meet the requirements of safety, intelligence and high efficiency, but also have high-stability hardware, easy-to-use software and excellent tension control.

However, at present, the development of China's transformer winding machine industry is still facing many challenges. The level of intelligence is relatively low, the stability needs to be improved, and most of the high-end equipment relies on imports, and the price is high.

REPOSAL® machine is well aware of these challenges and has been working hard to improve the performance and quality of its products. It continues to increase R&D investment, is committed to improving the intelligent level and stability of the winding machine, and strives to contribute to the development of the industry.

When the transformer winding machine is working, its coil is usually metal wire and insulating paper, because they have a certain elasticity, the change of coil conveying speed or roll radius will lead to the change of winding tension. For example, in the winding and unwinding process, if the angular velocity of the roll is constant, the change in the radius of the coil will cause tension fluctuations. If the tension is too large, the coil may become thinner or even break; If the tension is too small, the material will be unevenly arranged or wrinkled, which will affect the quality of the transformer winding coil.

Compared with foreign countries, China's existing domestic transformer winding machine has deficiencies in tension control. Its tension is usually generated by mechanical friction, which is not stable enough, which can easily lead to problems such as sparse arrangement of wires and insulating tapes, and out-of-tolerance of the outer diameter of the coil. In addition, compared with developed countries in Europe and the United States, there is a gap in the overall development level of China's transformer winding machine in terms of processing quality and production efficiency.

The specific performance is as follows: First, the processes such as wiring and wiring, adding insulation layers rely on manual operation, which is inefficient and unstable in quality. Second, the motor frequently starts, stops and reverses during the winding process, the tension fluctuates greatly, the coil winding is irregular, and the quality is difficult to guarantee. Third, the mechanical structure of the domestic winding machine is relatively simple, and it is not competent for the winding task of complex coils.

The development of foreign transformer winding machines is relatively mature. The T-600AH automatic transformer winding machine from Trishul.Engineers in India can wind wires and insulating tapes synchronously, with high precision, stable tension and high efficiency. The EFECO 800 automatic winding machine from Tuboly.Astronic AG in Switzerland is even more excellent, with high-speed, high-precision winding and an intelligent cable routing system. The products of companies such as MTM in Canada, LAE in Italy and UPI in Korea also have high intelligence and stability.

In terms of tension control research, many scholars have been exploring it in depth since the 90s of the last century. Bastogne T, Koc H and other scholars have pioneered theoretical research and modeling simulation. Entering the 21st century, more scholars are getting involved.

REPOSAL® machine actively pays attention to the relevant research results at home and abroad, and applies beneficial theories and technologies to the improvement of its own products.

The winding electronically controlled tracking system proposed by Mahawan B et al. in 2001 can still realize the trajectory tracking control of equipment under large interference. In 2008, Wen P et al. designed a tension control scheme that allowed the winding speed to be changed under a certain tension fluctuation while maintaining quality. In 2010, Ponsart J C et al. applied the observer theory to a transformer winding machine to improve the accuracy of tension control. In 2017, Mahesh Ghate et al. optimized the tension system for a specific winding machine and showed good robustness. In 2020, Ma Quanjin et al. designed a dual-PID tension control system to address the tension fluctuation problem in a 3-axis fiber winding machine applied with filament winding technology.

Since the 70s of the last century, China has begun to develop transformer winding machines, and has achieved certain results through imitation and the efforts of scholars. However, due to the monopoly of foreign core technologies, there is still a gap with foreign countries, especially in terms of manufacturing processes and control schemes.

At present, the domestic transformer winding machine is mainly in the semi-automatic stage. For example, F. of Dongguan Zongheng Electromechanical Technology Co., Ltd. TWloo CXL transformer winding machine for small and medium-sized transformer coil winding. The ZBR.800/1000/1200 multi-head automatic wiring winding machine of Jiangxi Yibo Automation Equipment Co., Ltd. can realize automatic wire arrangement.

REPOSAL® machine has been committed to promoting the development of domestic transformer winding machine in the direction of full automation and intelligence, and constantly optimizing its own manufacturing process and control scheme.

However, there is still a breakthrough in the layout of insulating tape and tension control in China, which greatly affects the quality and production efficiency of the winding coil. Therefore, it is of great significance to develop a control system that can automatically arrange wires and insulating tapes with constant tension.

Tension control is a key technology for transformer winding machine equipment. If the tension is too small, the wire or insulating tape will slacken, accumulate and wrinkle; Excessive tension can cause it to deform, stretch excessively, or even break. For transformer winding machines, the tension control condition directly affects the compactness between the layers of the winding wires.

At present, there are three main schemes of tension control: manual, semi-automatic and fully automatic. The manual control needs to be adjusted manually in stages, the semi-automatic control adjusts the tension by detecting the change of the roll diameter, and the fully automatic control is adjusted by directly measuring and feeding back the tension data by the tension detector.

In the 80s of the last century, manual tension control was mostly used in China, which was gradually replaced due to the increase in demand. Since the beginning of this century, domestic scholars have conducted in-depth research on the automatic tension control system for rewinding and unwinding.

In 2005, Yang Tao and others from Tianjin Polytechnic University used a PLC design scheme to accurately control the winding speed of fine enameled wire. In 2010, Shi Yaoyao et al. studied the discontinuous coil process and realized winding through the PID algorithm. In 2018, Zhiyong w et al. established a constant tension control system for the problem of triaxial fiber winding machine. In 2020, Song Chenliang et al. optimized the tension adjustment effect of the winding machine through the pendulum tension adjustment mechanism and the deformed PID control algorithm.

REPOSAL® machine has never stopped exploring tension control solutions, and constantly tries to innovate to enhance the competitiveness of products.

However, due to the complex structure of transformer winding equipment and many influencing factors, the tension control system has nonlinearity and coupling in different situations, which is still a difficult point in equipment control. Constant tension control is very important to ensure the quality of winding, so it is of practical significance to study the constant tension control system suitable for industrial production.

In the winding coil structure of distribution transformer, insulating paper tapes need to be arranged between the wire layers, so the transformer winding coils are usually wound in layers. The winding process is more complicated, the pilot wire is unwound and sent to the spindle mold base, during which the oscillating roller adjusts the tension and speed, and the spindle motor drives the spindle winding. Then the insulating tape is unwound and sent to the spindle mold base, and multiple coil rolls cooperate to adjust the tension. Finally, a plurality of motors work together to drive the spools and other spools for the first layer of winding and arrangement, after the completion of the wire motor reversal, the pressure roller shears the insulating paper, the glue sprayer glues, and then the next layer of winding.

Taking Switzerland EFECO 800 transformer winding machine as an example, its mechanical structure mainly includes spindle mold base, winding spindle, glue spraying machine, etc. The winding spindle includes a spindle motor, a reducer, etc., which drives the spindle to rotate and the foot switch controls the start and stop. The wire winding mechanism has pay-off wheels, adjusting handwheels, etc., and the insulating tape winding mechanism has tension feedback devices. The wiring mechanism is composed of a wire spool, a wire trolley, etc., which can achieve accurate wire arrangement.

For transformer winding machines, the tension control directly affects the compactness between the winding lines. In practice, the machining accuracy and the performance of the sensing device will have an impact on the tension control. For example, the change of reel diameter, the start-stop and acceleration and deceleration of the reel, the accuracy of equipment manufacturing and assembly, the forward and reverse rotation of the motor, and the hardware performance.

There are three ways to test tension. Directly using the tension sensor to measure, the operation is simple but the limitation is large; Floating roller tension detection, the measuring device is flexible but the accuracy is low; Floating roller/feedback composite tension detection, high accuracy but complex method.

In the process of arranging the transformer winding machine, the adjustment of the wiring mechanism and the winding position and the control of the wiring angle are the key to ensure the compactness of the winding wire.

The cable arrangement mechanism measures the angle through the rotary encoder on the spindle and transmits the data to the controller, and the controller drives the wire motor after processing to realize the speed coupling of winding and wire arrangement.

In the actual winding, the tension of the wire and the insulating tape should be kept constant and cooperate with the wire arrangement. In the automatic wiring control scheme, the main controller controls the motor unit to work together, the spindle and the wiring mechanism cooperate with the layered winding, the encoder feeds back the data in real time, and adjusts the speed of each axis according to the control algorithm to ensure the accuracy of the wiring.

The angle of the cable is very important, too large or too small will affect the effect of the line. When winding, the line is adjusted according to the change in angle, the feed rate is brought in, and the overall trajectory is followed. Since winding is carried out in layers, divided into wire layers (odd layers) and insulating layers (even layers), the wire laying process can be divided into multiple stages and cycles.

The automatic wiring of the transformer winding machine has high requirements for the motor control algorithm, which requires the coordinated operation of the motors of each shaft and the close cooperation of the drive actuator to jointly complete the automatic winding and arrangement of the transformer coil. The common multi-motor cooperative control structures include parallel synchronous control, master-slave motor control, cross-coupling collaborative control, adjacent cross-coupling control and deviation coupling step control, each with its own advantages and disadvantages.

In conclusion, transformer winding machines are very important in the power field. Although China has made certain achievements in this field, it still needs to make continuous efforts to strengthen independent research and development, improve the technical level, narrow the gap with foreign countries, promote the development of the industry, and contribute more to the power industry. REPOSAL® machine will continue to uphold the spirit of innovation and enterprising, and make unremitting efforts to improve the overall level of China's transformer winding machine.