Cpld-based Three-phase Induction Motor Soft Starter Control System

In this paper, we mainly discussed the application of the complex programmable logic devices (CPLD) on soft-starting of the three-phase Asynchronous motor. The controller of soft-starting of new type three-phase asynchronous motor mostly adopts circuits which change the stator voltage of asynchronous motor, which has simple structure, reliable performance, low cost and facile with transducer. Accordingly, the maintenance in application on comparison high-power asynchronous motor of the controller becomes wider and wider. But existing systems mostly have some shortages, for example, too big, imprecise control, simple man-machine interface and low intelligence.On discussing the CPLD controller,the MCU controller,the CPLD+MCU controller ,we adopt the CPLD+MCU controller. The CPLD is used to produce the thyristor trigger signal and complete the MCU interface function. This method makes the system has a wide triggering angle, high controlling, precision and better symmetry output pulses. The motor soft starter is a new technique of the fastest development, which can not only adjust the motor current of start and stop, but also rectify starting torque and perform soft-stop. It has outstanding performance in the face of protection of driving gear and maintenance the quality of electric network.The in fluencies of the programmable logic devices on electronic system design and the design methods and flow of EDA are firstly discussed.Next, we introduced the starting properties of the three-phases Asynchronous motor ,and discussed the starting current, the starting torque,and builed the simulating model of the three-phases asynchronous .Thirdly, according to the plan of "CPLD+MCU", we designed the hardwaresand software .By the methods of "TOP-DOWN", we divide the soft-starting control system into modules: MCU interface module, ADPLL module, and PULSE module, and detailed explained the realization of the modules.Max+ plusll is used as the develop plat, and all of design is complied and simulated successfully, and the simulation waves are also provided.