Steady-state analysis of a doubly fed asynchronous machine supplied by a current-controlled cycloconvertor in the rotor

Abstract

This paper deals with a doubly fed asynchronous machine (DFAM) supplied by a current-controlled cycloconvertor (CCC) at the rotor, and AC mains at the stator. A microprocessor is used to achieve control of the system by magnitude, frequency or phase shift of the output currents of the cycloconvertor. It also ensures the bank selection process. The mathematical model of the DFAM presented is based on a vectorial representation. Steady-state analysis of the CCC-fed DFAM has been carried out in the synchronous reference frame, and expressions of various output variables are developed. Performances of the drive are determined analytically. After theoretical analysis, the effect of the control parameters is investigated. Experimental results obtained show a good correlation with analytical predictions. Moreover, the range of variations of load angle must be limited to be within a certain value to verify stability conditions, and currents must not exceed the upper limits that the machine can carry.