VECTOR OPERATOR

摘要

PROBLEM TO BE SOLVED: To observe a vector amplitude value of a three-phase line current which is inputted to a three-phase induction motor by a DC current value in real time. SOLUTION: Current values of selected two lines (e.g. phase U or phase V) through which a current is supplied to a three-phase induction motor 16 are detected. The product of both of the current values is obtained by means of a multiplier 6 and square values of each of the current values are obtained by means of square multipliers 5, 7. The product and sum of the square values are obtained by means of an adder 8 and a constant is multiplied thereto by means of a constant multiplier 9 and a square root is obtained by means of a root operator 10. As a result, a synthetic vector current value of the two-phase condition converted from the three-phase condition is obtained as a DC current value in real time.