High Performance Servo Control System For Large Medical Equipment

In recent years,with the increasing aging of the population and the increasing government support,the medical equipment market will be further expanded.The medical equipment of the motor is equipped with the corresponding servo controller,and the performance requirements of the servo controller are relatively high.Because each large medical equipment is not the same to the servo control system,but it is a variable frequency speed regulation device.A servo control system for rotary motor based on CT scanning frame of motion parameter design,and through the analysis of the direct torque performance requirements this paper decides to adopt the servo control of the classical control system of three level inverter(DTC)control.First of all,this thesis,from the research of diode clamped three level(NPC)inverter working principle,to apply to the three level(NPC)inverter of the traditional space vector modulation(SVPWM)for a detailed analysis.According to the working principle of the three level inverter,the distribution of the three level space voltage vectors is obtained,and the division of the sector,the selection of voltage vectors and the calculation of the action time are explained in detail.The space voltage vector modulation(SVPWM)of three level inverter is simulated in MATLAB/Simulink environment.Secondly,the mathematical model of the two-phase stationary(Clark)coordinate system is obtained by the mathematical model of the three-phase static coordinate system of the asynchronous motor.And the direct torque control is studied in this model.The direct torque control of direct torque and flux control,so the flux observation method,the need for direct control of the torque estimation,the stator flux linkage hysteresis regulator and torque hysteresis regulator in detail.Finally,direct torque control based on direct torque control has a lot of disadvantages.Scholars have put forward a fixed synthesizing vector modulation method,this method has a certain effect,but there is no effective solution to the midpoint voltage of three level inverter,unbalanced voltage jump and power device switching loss problem.In this paper,a new method for the synthesis of fixed direction is improved,and a new method of direct torque control is proposed.Due to the limited experimental conditions,the control system does not do the experiment in CT,simply built in the laboratory of asynchronous motor control system of three level inverter,and the experimental test.