Research On Control System For Non-sinusoidal Oscillation Of Continuous Casting Mold Driven By Servo Motor

Non-sinusoidal oscillation of continuous casting mold is one of the key technologiesin continuous casting industry. It can improve the casting quality and increase productionefficiency. In this paper, with the backgroud of national invention patent“Non-sinusoidaloscillation generator for continuous casting mold driven by servo motor”, permanentmagnet synchronous motor that is one of widely used AC servo motors is used as drivingdevice, and control system for non-sinusoidal oscillation of continuous casting molddriven by permanent magnet synchronous motor is researched.Firstly, basic mathematical model of permanent magnet synchronous motor is given.With coordinate transformation theory of vector control, mathematical model ofpermanent magnet synchronous motor in two-phase rotating dq coordinate system isdeduced. It provides theoretical foundation for later study.Secondly, according to the need for position control of mold, position control ofpermanent magnet synchronous motor is studied, and an adaptive terminal sliding modecontrol algorithm is given. The fast terminal sliding mode control method can result in therapid convergence of the control system errors. Meanwhile, in order to weaken thechattering phenomenon, an adaptive algorithm is used to estimate the upper bound of loaddisturbance uncertainty, and the sign function in the control law is replaced by the bipolarsigmoid function. The effectiveness of the method is demonstrated by the simulationresults.Thirdly, with the requirement for variable angular speed of permanent magnetsynchronous motor in the control system for non-sinusoidal oscillation of continuouscasting mold, the problem of motor speed tracking is studied, and a fast dynamic slidingmode control algorithm is given. The dynamic sliding mode control can effectivelydiminish chattering. Meanwhile, the reaching law is designed with the concept of fastterminal sliding mode, which can result in fast convergence of the system. The simulationresults show that the designed controllers can make the motor rapidly and accurately trackgiven speed signals, and the system is robust to the load disturbances. Finally, the experiment platform of control system for non-sinusoidal oscillation ofcontinuous casting mold driven by servo motor is designed and constructed with Siemens1FT6 servo motor, SINAMICS S120 servo drive, S7-400 PLC and other hardware.Hardware configuration and programming of control system are carried out by STEP 7software and STARTER software. For different frequencies and modification ratios, theexperiment that servo motor tracks given speed curves is carried out. The experimentalresults demonstrate the feasibility of the designed control system.