TRANSIENT ANALYSIS OF STATIC SLIP ENERGY RECOVERY DRIVE

Abstract

In recent years, efforts have been made to introduce methods through which variable speed feature could be attained in a.c. drives. Due to this process, various methods have cropped up for both cage and wound rotor type of induction motors. The cage type of induction motors require a variable frequency voltage or current source whereas the wound rotor type induction motors are run from fixed frequency source and speed control is exercised from rotor side. In static slip-energy recovery system, slip-frequency rotor voltages are rectified . by a diode bridge and applied to the line commutated controlled thyristor bridge, which operating as an inverter returns energy back to the supply. The energy fed back depends upon the :supply voltage, the direct input voltage and the inverter firing angle. The direct feed back of slip-energy into the supply results in a fairly good variable speed drive with firing angle as the speed control parameter. The aim of the present study is to develop a mathematical model for analysing the transient behaviour of static slip-energy recovery drive system. Accordingly an idealised model for the system has been developed with the system analysed in synchronously rotating reference frame. The generalised two-axes non-linear differential equations of the system