THE USE OF ISOLATED PHASE CONTROL SYSTEM FOR CORRECTION THE ASYMMETRICAL OPERATIONAL MODES OF VECTOR-CONTROLLED INDUCTION ELECTRIC DRIVE

Nowadays it is known a number of methods for field-oriented control of induction motors. However, developed methods do not allow one to use in full advantages of vector-controlled systems for electric drives working under electrical or magnet asymmetry of the motor's stator winding. Along with this, as a result of operation the electric drive with damaged motors, it observes significant deterioration of the control quality, the losses significantly increases and it appears variable components of electromagnetic torque and active power. In this work, basing on the analysis of orthogonal components of electromagnetic torque it is shown, that compensation of the influence of stator windings asymmetry on induction motor's characteristics is achieved by reducing the flux linkage of the motor's asymmetrical phase. As the use of classical approaches for creation the vector-controlled systems, which based upon the use of orthogonal models of the motors, do not allow one to influence on each phase separately, so in order to make in possible to correct asymmetrical operational modes of electrical motors it is necessary to use the system with separate regulation for each motor phase. The possibility to provide high dynamic characteristics of electric drive and independent control of the flux linkage and electromagnetic torque of the motor in the systems with isolated phase control could be achieved using presented in this work method for compensation the cross-connections by stator current projections in three-phase coordinate system. The conducted researches of the current and flux linkage regulation errors in a fixed coordinate system confirms the possibility of usage the classic approaches for the synthesis of regulators for vector-control system in case of regulation the periodical signals.