Study On Variable Frequency Variable Speed Technology Of Hoisting Mechanism Of A Crane

With the demand of the engineering construction development, tower cranes become necessary machines in modern architecture buildings. In the gearing of cranes, the most important and most typical gearing is hoisting mechanism. Capability of the hoisting mechanism has great influence on working efficiency and security of crane. Frequent startup and brake is main characteristic in course of crane work. So well behaved speed regulation system is an important guarantee of stable and reliable work.According to poor capability of speed regulation, low efficiency and great energy consumption in speed regulation method of hoisting mechanism, the paper researches control algorithm by electric machine vector controlling variable frequency control and compares simulation and experiment based on analyzing characteristic and principle of speed regulation.To improve the stability, safety and high efficiency of hoisting mechanism in running, the mechanical character of hoisting mechanism and the relation of working parameters are analyzed.By analyzing the structure character and speed adjusting property of the method currently used in tower crane, an asynchronous motor module was built based on vector control theory; comparative analysis of the character of PID controller and fuzzy controller, the control property of hoisting mechanism of tower crane was analyzed by the control system simulation. It was shown in simulation result that fuzzy—PID control method has the advantage of high property in dynamic response, less error in stability and less over-swing, and the dynamic and stabilityproperty is better than any single PID controller or fuzzy controller, so fuzzy—PID is an effective method to improve the property of hoisting mechanism, and it is suitable to apply it in a large starting torque working situation.Finally, experimental research of the variable frequency control system was made based on a crane model. Designs and calculating selected types of system components are finished. Controlling capability of variable frequent speed by electric machine vector is analyzed by testing capability parameters of motor current, torque and hoisting speed.