| abstract |
(57) [Abstract] [Purpose] Regarding the speed control of an induction motor, the problem of accuracy deterioration of vector control without speed sensor at low speed operation, Also provided is a vector control device that solves the problem of accuracy deterioration of vector control with a speed sensor due to secondary resistance fluctuation and enables high-accuracy speed control including near zero speed. [Structure] A vector control device of an induction motor is provided with a function of measuring a leakage inductance which changes depending on a position of a magnetic flux of the electric motor, and a magnetic flux calculator for detecting the magnetic flux from the change of the inductance is provided, and the electric motor is based on the detected magnetic flux. To control. [Effect] Since the magnetic flux in the motor can be estimated without being affected by the primary resistance of the induction motor, vector control based on the magnetic flux of the motor becomes possible, and high-accuracy speed including near zero speed can be achieved. And torque control can be realized. |