变频调速在彩涂机组固化区的应用

彩涂线工艺段的变频张力控制主要是固化炉区钢带的传动控制，钢带传动控制除了要满足生产线的速度匹配限制之外，还需要实现张力控制功能。张力控制主要是防止钢带在经过固化炉的时候由于张力过大而在热效应下产生拉伸变形，从而影响成品的质量。

固化炉区钢带的张力控制可以通过闭环转速控制模式来实现，彩涂线工艺段即通过调节固化炉的人口速度和出口速度之间的差值来控制钢带悬空时所受的张力。由于彩涂线工艺段钢带自身具有重力效应，并且在固化炉人口驱动辊和出口驱动辊之间由于没有支撑，因而若要使钢带在运动过程中不会受到过多的拉伸力以致变形，必须使其产生一定程度的悬垂，并且在整个设备运行过程中必须保证悬垂度处于适当的波动范围中。速差调节的实质是一种张力的PID 控制方式，它需要依靠额外的张力传感器反馈作为速度调节的依据。虽然这种控制方式相对简单，然而在系统启动/停止或者加速/减速过程中要达到稳定的张力控制效果还是不太理想，较容易影响到涂层烘干的质量。

除了通过以上模式来控制达到防止张力波动的方法外，固化炉区钢带的张力控制也可以采用一种以定子磁通和转矩为主要控制变量的新型控制技术--DTC 控制技术，其原理是交流电机传动系统中的直接转矩控制是基于定子两相静止参考坐标系，一方面维持转矩在给定值附近，另一方面维持定子融能沿着给定轨迹(预先设定的迹，如六边形或圆形等)运动，对交流电机的电磁转矩与定子磁链直接进行闭环控制。

The frequency conversion tension control of the process section of the color coating line is mainly the drive control of the steel belt in the curing furnace area. The steel belt drive control not only needs to meet the speed matching limit of the production line, but also needs to realize the tension control function. Tension control is mainly to prevent the steel strip from stretching deformation under thermal effect due to excessive tension when passing through the curing furnace, thus affecting the quality of finished products.

The tension control of steel strip in curing furnace area can be realized by closed-loop speed control mode. In the process section of color coating line, the tension of steel strip in suspension can be controlled by adjusting the difference between the population speed and outlet speed of curing furnace. Because of the gravity effect of the steel strip in the process section of the color coating line, and because there is no support between the driving roller and the outlet driving roller of the curing furnace, if the steel strip will not be deformed due to excessive tensile force in the process of movement, it must have a certain degree of suspension, And in the whole process of equipment operation, it must be ensured that the sag is in an appropriate fluctuation range. The essence of speed difference regulation is a kind of tension PID control mode, which needs to rely on additional tension sensor feedback as the basis of speed regulation. Although this control method is relatively simple, it is not ideal to achieve stable tension control effect in the process of system start / stop or acceleration / deceleration, which is easy to affect the quality of coating drying.

In addition to the above control mode to prevent tension fluctuation, a new control technology DTC control technology with stator flux and torque as the main control variables can also be used for the tension control of steel strip in curing furnace area. Its principle is that the direct torque control in AC motor drive system is based on stator two-phase static reference frame, On the one hand, it keeps the torque near the given value, on the other hand, it keeps the stator melt energy moving along the given track (such as hexagon or circle, etc.) to directly control the electromagnetic torque and stator flux linkage of AC motor.