The Research Of Comprehensive Control System For Induction Motor Based On Field Bus

With the development of economy, the production-scale of many industries is bigger and bigger. The quantity and range of high voltage induction motor is more widespread used. It is well known that induction motor which is direct-on starting has many malpractices. When the induction motor light-loading is running, the power loses increase, the efficiency and power factors both greatly reduce. When many induction motors are operating, the communication between computer and controllers is very difficult. Therefore it has extremely vital significance to implement effective control on induction motor, avoiding the electrical network impact, guarantying the security of the induction motor, enabling the computer control group induction motors.Firstly, the development of the soft starting and saving control for High Voltage Induction Motor and the field bus technology are introduced at home and abroad in this paper. It is analyzed the variation of current and torque during induction motor starting process. The principle of the SCR adjusting voltage circuit and the starting model of soft starter are introduced. The voltage adjusting model SCR is used in this paper. The simulation model of high voltage induction motors soft starting control is created by MATLAB. The soft starting control model of the current-limit start and the voltage-slope start are simulated. The results of the simulation proved that the soft starting control can effective reduce start current as high voltage induction motor start up directly and the motor could start up smoothly. Secondly, the power and the dissipation of induction motor are analyzed. The change rule of the induction motor power factor angle, the effect of the stator terminal voltage and the detection method of power factor angle have been studied. When the induction motor is running in on-load or light-load, the power factor angle closed power-saving control is proposed. The simulation model of Induction motor power-saving control is established by MATLAB and the power factor angle closed power-saving control is simulated. The results of the simulation proved that power factor angle closed control saves power obviously. Thirdly, the problem of the series connection of SCR to soft-starting of Induction motor the static and active voltage balancing are studied. The simulation model of SCR series is created by PSPICE. The voltage balancing circuit and no voltage balancing circuit are simulated and the parameter is defined. The results of the simulation proved that voltage unbalancing of series SCRs is solved and some series SCRs voltage balancing is well completed. Finally, the software and hardware of the 6kV high voltage induction motor controller is designed. As for the part of software, Current and voltage zero cross detection circuit, synchronism signal detection circuit, Current and voltage detection circuit and CAN bus interface circuit and so on are designed. As for the part of hardware, the overall design and the main flow chart are given. Then the program thought and implement method such as adjusting voltage module, power-saving module, CAN communication module are given. The computer monitor interface is designed.