Fast Algorithm of Virtual Value for the Novel Soft Starter of Induction Motors

A fast algorithm of the virtual value for a three-phase system is presented in this paper. The virtual value of a three-phase system is simply calculated according to the instantaneous value of three-phase components. Compared with the conventional calculating method using lots of sampling data in one or several cycles, the proposed method not only simplifies the operating process but also shorten the response time. The updating period of the virtual value is only half system cycle. So it is suitable for the system where the close-loop control and protection are carried out on basis of the virtual value. The experimental results prove that this fast method is valid.