The Research Of Chopped-Soft-Starter

Along with the development of power electronic technology and microcomputer control technology,to reduce the big electric current produces the electrical network voltage impact and so on negative influence when the three-phase asynchronous motor starts,the article in view of the present situation of domestic electric motor soft start at present and future trend of development,it expands the realizing method of three-phase exchange asynchronous electric motor chopped wave style.It proceeds many studies including main circuit,controlling circuit,driving circuit and the design of system's software,whose main thought is that pulse controls electronic power switch component IGBT to be on and be off by the fact that DSP produces PWM,it adjusts the empty space ratio and makes the voltage that the stator holds when the electric motor start electric current according to in advance setting up good curve change,so it reduces the starting electric current and realizes the asynchronous electric motor starts.The main body of the text carries out analysis about characteristic property of three-phase asynchronous electric motor starting firstly,and compares with three-phase exchange pressure regulating circuit as well as method is in progress owing to that three-phase exchange pressure regulating three-phase asynchronous electric motor soft starts. And then,it introduces the composition structure of the chopped soft wave style and analyses the design of main circuit, controlling circuit, protecting circuit,detecting circuit and system's controlling software. The host circuit adopts the diode being able to bears bigger IGBT of pressure and restoring power quickly to be composed of three-phase chopped wave circuit,the streaming circuit is composed of three-phase commutation bridge and IGBT adding,The pulse broad modulation signal comes into being from the control circuit,it carries out power amplification by KA959 drives circuit to make IGBT be on and be off. Be that the starter output quantity has carried out adjustment, system has designed voltage and the electric current sampling circuit ensure that the control circuit real time field is face to face soft. Specifically for being unlike the need that capacities electric motors control,system hardware adopt the modularization design plan. The article introduces the function and structure of the system hardware that modularization design procedures designs in detail. Finally the article introduces the designing method of software based DSP and explains the basic method and concrete step that DSP produces PWM.