The Application Research Of Vector Inverter In Direct Twisting Machine Control System

With the continuous improvement of electrical control technology, themulti-motors coordinated control becomes a hot spot. Direct twisting machinecontrol system is composed of multiple motors, uses in the production of automobiletire cord, which production process requires keeping yarn tension constant and goodshape after twisting. This article mainly introduces a kind of multi-motorsparallel-connected driving which adopts vector frequency conversion controlscheme based on direct torque control, and also does some relatively design aboutthe energy-efficient system of common DC bus.The topology and principle of inverter is firstly analyzed in this paper, and theclassical DTC scheme based on switch table (ST-DTC) and the modified DTCscheme based on space vector modulation (DTC-SVM) are investigated. In ST-DTCscheme, the electromagnetic torque and stator flux is controlled by hysteresiscontroller. In DTC-SVM scheme, the hysteresis controller can be replaced by PIregulator. Compared with ST-DTC scheme, the simulation results show that theDTC-SVM scheme has swift motor response, low torque ripples and constantswitching frequency.Secondly, a kind of parallel-connected multi-motors driving scheme based onDTC-SVM is presented by combining DTC-SVM scheme with the average theorywhich implemented in parallel-connected multi-motors system. The methodaverages the parameters of multi-motors and gets the average motor model, thenapplies the DTC-SVM scheme to this model. The simulation results show that theparallel-connected multi-motors driving system can be rapid and coordinatedoperation in the range of allowable torque error. This theory is successfully appliedto the spindle motor control issues. The parallel-connected motors which are drivenby inverter MFC710whose parameters are given can achieve high rotational speedand steady-state operation.Finally, the technology of common DC bus based on PWM rectifier and theenergy-efficient techniques are proposed. It is proved that the PWM rectifier whichuses voltage and current double-loop control scheme possesses fast dynamicresponse and sound steady-state performance through simulation. The common DCbus system consists of the PWM rectifier and multiple inverters which use theDTC-SVM scheme. The simulation results show that the regenerate energy can beefficiently utilized, so that the energy saving effects increase remarkably.