The Research And Manufacture Of AC Asynchronous Motor Soft Starter On Double AT89S52

Three-phase asynchronous motor has a wide range of application in industry, agriculture, transportation business, defense industry and other walks of life. This kind of motor has some advantages such as simple structure, convenient manufacture, reliable operation and low price. But the small starting torque and the high starting current which is 4 to 8 times higher than the rated current are the obvious disadvantages. In order to reduce the strike to the electric net work as asynchronous motor starts up directly and eliminate the negative influence that brought about by switching of contact when it starts up with reduced-voltage means, a kind of thyristor-regulator soft starter on SCM is researched in this paper.Now the domestic power is in short supply and the policy of energy-saving emission reduction is strongly advocated. The soft starter has outstanding representation in saving energy. The application of the soft starter is quite amplitude for the advantages it owns. The foreign products own the most percent in domestic market. Though the foreign products have high quality, the quality-value ratio is quite low. It is very hard to realize popularization in domestic market. So a soft starter with low price and high performance based on the AT89S52 is presented in this paper.A voltage adjusting model with SCR is used in this soft starter. By regulating the amplitude of asynchronous motor's voltage, it realizes the functions of the voltage-slope start, the current-limit start, the soft-stop and so on.This article introduces the working principle of the SCR adjusting voltage circuit and the starter's main circuit, the hardware structure and functions of the soft starter and the software program design. The three-phase regulating circuit of asynchronous motor system is analyzed and simulated by MATLAB. The results of the simulation show that the system based on the three-phase regulating circuit can reduce the high starting current as asynchronous motors start up directly.The operation of this soft starter is simple and easy. It also could be able to follow the change of the load to make sure that the asynchronous motor starts up smoothly. The soft starter reaches the requests of improving the performance of the asynchronous motor starts up through testing, it could start up smoothly and reliably under the condition that fill the requirement of starting torque and the starting current of the asynchronous motor is controlled.