The Research Of Soft Start Based On Weightiness Load On The Double-variable Ac-ac Converter

This paper describes the method of soft start on the motor and of the development of VVVF and points out the inadequacies of the traditional soft and the advantages of VVVF variable-frequency speed regulation and the lower cost. The double- variable AC-AC Converter control of a reliable, simple structure, lower cost, and it can overcome the shortage on common converter. Based on analyzing the shortcoming of one-variable control theory, two-variable control theory and natural non-circulating current work mode of AC-AC transducer rare brought forward. The paper deduces all compensation formula at lower frequency when the Control Strategy uses constant pressure frequency ratio bases on induction motor steady mathematical model. Second, the simulation model of double-variable AC-AC Converter is established. Motor torque characteristic on constant pressure frequency ratio and all Voltage compensation is certificated. The contrast of motor starting current and torque shows that the staring of the AC-AC converter at Heavy load can get the effect of Soft Start. Last, The experimental device at Heavy load and all voltage compensation is designed. The paper analysis the reasons of the bias Between the experimental and theoretical.