Patent ID: 7408322

Claim:
A device for determining a constant of a rotating machine, comprising: test number selecting means for outputting a test number n, selected from 1 to N (N≧2), and outputting a phase signal q determined by a predetermined condition that is previously set based on the test number n; test means for supplying an alternating voltage to the rotating machine based on the test number n and the phase signal q to obtain and output a reference phase gain (a( 1 ), a( 2 ), . . . , a(N)) and a 90-degree-delay phase gain (b( 1 ), b( 2 ), . . . , b(N)) based on values of the phase signal q corresponding to 1 to N of the test number n; and rotating machine constant calculating means receiving the reference phase gain (a( 1 ), a( 2 ), . . . , a(N)) and the 90-degree-delay phase gain (b( 1 ), b( 2 ), . . . , b(N)) and then calculating a constant of the rotating machine using the reference phase gain and the 90-degree-delay phase gain.