METHOD AND APPARATUS FOR MEASURING UNBALANCE QUANTITY OF ROTOR

PROBLEM TO BE SOLVED: To provide a rotor unbalance quantity measuring apparatus which even when rotation of a rotor is changed, is capable of always highly accurately finding out a spectrum of a primary frequency component of the rotation as compared with a conventional apparatus.SOLUTION: A digital vibration signal is generated by A/D converting a vibration signal obtained by detecting rotation vibration of a rotor 30. A digital reference signal is generated by A/D converting a reference signal synchronized with a frequency f of a rotational frequency signal of the rotor 30. A multiplied rotational frequency signal is generated by multiplying the frequency f of the rotational frequency signal by a multiplication ratio m, a frequency division ratio d is suitably set so as to obtain a desired sampling frequency fs, and the multiplied rotation frequency signal is frequency-divided. The frequency f of the rotational frequency signal and a component adjacent to the rotational frequency signal of the digital vibration signal and the digital reference signal are selectively transmitted through a digital tracking filter by using the sampling frequency fs, and FFT operation for data of the component transmitted through the digital tracking filter is performed.