The Applications Of Three-Level Medium Voltage Inverter MV7000in Twenty-Roller Mill Of Cold Rolling Mill

In the field of steel rolling, cold rolling mill train is the key equipment in steel rolling process, which determines strip steel’s quality, thickness and property. And the development of variable frequency speed control technology in electrical engineering filed, realized high precision control of rolling mill drive device, and improved product’s quality, productivity, yield, and technology level, which make product reach manufacturing process requirements.The first-stage of An-steel high performance silicon-steel project had built two production lines of cold rolling mill, by single stand and twenty-rollers reversing mill of French Machinery Group DMS Company. This paper is based on twenty-roller main mill as research background, to analyze the rolling mill’s main drive system. We use three-level medium voltage inverter MV7000, researched and developed by CONVERTEAM Company, make high precision control of the mill’s asynchronous AC motor of main drive.Firstly, this paper combines the development of frequency conversion technology, introduces the working principle and vector control theory of AC asynchronous motor. In this paper, a detailed study of the theory of speed control on drive motor and three-level medium PWM control mode is expounded.Secondly, on the basis of the requirements of twenty-roller mill process, this paper works on design, type selection, configuration of hardware of main drive system, and so on. This paper introduces the specific situation of configuration for inner hardware in MV7000inverter. Including, the rectifier unit cabinet AFE, DC bus cabinet DCC, inverter unit cabinet INV, AC output cabinet, control unit cabinet, water cooling unit, and other configuration.Finally, this paper uses the process of asynchronous motor adjustment as reference to debugging the system of the main drive inverter MV7000for twenty-roller in cold rolling.Furthermore,it also makes detailed research on the experimental scheme of motor in various kinds of speed control mode. And at last, it verifies that both motor operating speed and torque performance reach the static and dynamic system requirements.All the debugging processes and experimental conclusions in this paper are valuable experiences for debugging and maintenance in the future work.