METHOD FOR MAINTAINING DURABILITY OF THREE-PHASE VALVE MOTOR

FIELD: electrical engineering; valve motors distinguished by wide control range. ^ SUBSTANCE: proposed method for maintaining durability of three-phase valve motor incorporating microcontroller control system upon occurrence of phase failure by maintaining circular revolving field involves evaluation of working condition of each of three phases in frequency changer and motor. Upon occurrence of phase failure phase current setting is changed by means of valve motor control system so that phase shift in two remaining phases equals pi/3 radians under phase-failure condition while magnetomotive forces in remaining phases of motor are maintained equal and load angle theta between phase voltage vector and emf reversed vector changes at theta = pi/2 under three-phase condition by load angle Psi found between phase current vector and phase emf reversed vector at Psi = pi/6 under two-phase condition. Phase failure bits for phases a, b, c and bit d = d=a∪b∪c, where ∪ is OR gate operation. Phase current setting is formed in case phase failure is detected in one of phases for leading or lagging phase of current vector using expressions given in invention specification. ^ EFFECT: provision for maintaining motor durability in case of phase failure by way of circular field rotation at extended speed control range. ^ 1 cl, 4 dwg