The Research Of The Soft Starter For Asynchronous Motor

In order to reduce the strike to the electric network 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 new method based on power electronics technology for improving the starting characteristics of 3-phase asynchronous motor is presented.The application of the soft starter is quite amplitude for the advantages it owns. The soft starter has outstanding representation in saving energy, so the soft starter has broad market all over the world. 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 DSP-TMS320LF2407A 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.The 3-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 3-phase regulating circuit can reduce the high starting current as asynchronous motors start up directly. This article also introduces the working principle of the SCR adjusting voltage circuit and the starter's main circuits the hardware structure and functions of the soft starter and the software program design.The operation of this soft starter is simple and easy, it has very high degree in intelligence, 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 the start-current of the asynchronous motor is controlled.