Design And Implementation Of Rotation Control Systemfor Multi-slice Spiral CT

Computed Tomography(Hereinafter referred to as CT)technology has rapidly developed with the improvement of medical treatment both home and abroad.Manufactures have paid great attention to the costs associated with CT,with increasingly fierce market competition globally.Therefore,reducing manufacturing cost of CT is of very important significance to medical equipment enterprises.CT is comprised of a fixed control system and a rotating control system.Through research and analysis of the system structure,a low cost compatible asynchronous motor rotating control system has been designed on the basis of existing main rotating servo control system to improve market competitiveness.The main works of this dissertation are as in the following:(1)System structure of NeuVizl6 CT is introduced,fixed control and rotating control systems have been analysed to realize the reducing of cost on the basis of meeting the system performance indicies.(2)From a cost reducing point of view,the existing structure,control mode,speed and position accuracy of the rotating control system were researched and analyzed according to system demand,which main purpose is to design a completely compatible low cost rotating control system using asynchronous motor and frequency converter as the executive component.(3)Simulation analysis has been conducted for the asynchronous frequency conversion control with the remaining rotating system structure,and it is concluded a structure design scheme and control method can be compatible with the original structure.(4)Equpment selection of asynchronous motor,frequency converter and resistor,and setting of parameters of frequency converter have been used for engineering implementation aiming at the cost reducing system structure and design scheme.(5)Functional verification and analysis have been done for the speed acceleration and deceleration control,rotating positioning,fault protection,electromagnetic radiation at the maximum speed,which proves that it can meet the system requirements of acceleration and deceleration,positioning accuracy,and statble of speed and can achieve the cost reducing design of fully compatibility.Through internal system verification,testing and clinical verification,the control system in this dissertation can meet design requirements.The experimental data showed that the new system was fully compatible with the original system,and the operating accuracy can reach 0.3%.Main indicies of acceleration time and position accuracy have been improved,which accelerates from 0 to Max.speed of 0.39s/r only taking 19.9s compared with previous 21s,and the position accuracy is improved from 0.3° to 0.24 °.