Nancal provides a complete set of variable frequency drive solution for single stand and multi-stand stainless steel reversible rolling mill. The motor drive device adopt Nancal NC EVFD series industry AC VFD which has multi-drives with common DC bus, the rated voltage can choose 380V,480V or 690V. The rectification part can be equipped with high-performance IGBT PWM rectification ISU1 module or economical IGBT 6-pulse rectification ISU2 module. These two kinds of modules all can support four-quadrant operation and up to 16 same specification modules operated in parallel to meet the driving requirements of large-capacity rolling mill.
Main rolling machine, reeling/unreeling machine and small winding/unwinding machine are hung on the public DC bus, making full use of the feedback energy of reeling/unreeling machine. Therefore, reducing the overall capacity of the rectifier unit and expense. The choice of common DC bus can also remove chopper brake and brake resistor to save space.
The overall control scheme of the reversible cold rolling mills is based on high-performance industrial microcomputers, programmable logic controllers (PLCs) and AC drive control systems. The latest all-digital system is used to form a fully distributed networked modern control system. An industrial fieldbus is used for data communication between the drive control system and the automation control system. The operation console is designed according to the principle of advanced, centralized and convenient.
The PLC is mainly responsible for converting the line speed and tension into the speed and torque limit acceptable by the VFD, and then transmitting it to the EVFD control system through the DP bus communication. The EVFD drive the motor according to the system setting mode, basing on the received speed reference and torque limit. The industrial microcomputers is responsible for the speed control and the load balance calculation of the upper and lower rollers.
NC EVFD series low voltage industry drive completely satisfy the requirements of stainless steel cold rolling mill, with a series of technical features such as modular design, multi-drives with common DC bus, high accuracy control of speed and tension, high power density and high reliability.