PURPOSE: To expand the range of operating speed by adopting one of the control, which makes the magnetic flux of a magnetic field system beneath the base number of rotation constant and makes the magnetic flux reverse-proportional with respect to the number of rotation when it is higher than the base number of rotation, and the control, which adjusts the armature current and voltage so that the current ratio of the components of the voltage induced in an armature winding becomes constant.
CONSTITUTION: The detected value of a rotation detector 36 is added to a speed command as the present speed in a speed detecting part 38, and the value is converted into the magnetic flux of a magnetic flux field system with an operator 39. The magnetic flux of the magnetic field system is made constant beneath the base number of rotation of a motor and made to change in reversely proportion to the number of rotation higher than the base number of rotation. The current flowing through this armature winding is obtained with an exciting current operator 40 and divided into the component in the same phase corresponding to the induced voltage of the armature winding and the component, which is perpendicular to the component in the same phase. The components are controlled with a DC-current control circuit 41 so that the ratio of the current components becomes constant. Thus, the range of the operating speed can be expanded.
MIZUNO TAKAYUKI
ASHIKAGA TADASHI
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