Patent ID: 6043617
Filing Date: 2000-03-28
Classification: H02P

Abstract:
A variable speed driving apparatus comprising:an inverter;a set of current detectors for outputting detected current values;a plurality of induction machines connected to said inverter;a plurality of speed detectors, each coupled to each of said induction machines;a reference angular frequency operating means for operating the rotating angular frequency of one of said induction machines bearing the heaviest load based on the output signals from said speed detectors;a first phase difference operating means for operating the first phase difference between the secondary side component of a reference current and a primary reference magnetic flux;a first reference slip angular frequency operating means, thereto said first phase difference is inputted;a first adder for adding the output of said first reference slip angular frequency operating means and the output of said reference angular frequency operating means and for outputting a primary reference angular frequency;an integrator for integrating said primary reference angular frequency;a detected current vector rotating means for converting said detected current values to a q-axis component perpendicular to said primary reference magnetic flux and a d-axis component parallel to said primary reference magnetic flux based on the output of said integrator;a d-axis current regulating means, thereto a d-axis component of said reference current value and said d-axis component of said detected current values are inputted;a q-axis current regulating means, thereto a q-axis component of said reference current value and said q-axis component of said detected current values are inputted; anda reference voltage vector rotating means for converting a d-axis reference voltage value and a q-axis reference voltage value to reference three-phase voltage values based on said output of said integrator.