| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for constant measurement wherein it is unnecessary to correct an on-voltage drop every control period and set on-voltage drop characteristics of a power element with accuracy. <P>SOLUTION: The revolution of an alternating-current motor 2 is stopped by an inverter controller 8 for the alternating-current motor. In this stage, a voltage phase is fixed at a preset arbitrary value by a sine wave generator so that alternating magnetic flux is produced. A voltage command for a sine wave with a frequency of fh is given, and the voltage command value is adjusted so that the magnitude of an output current becomes a predetermined value. When a predetermined time has passed thereafter, the average value Vave of the absolute value of the voltage command and the average value Iave of the absolute value of the output current are computed and the phase difference θdif between the voltage command and the output current is measured by an average value-phase difference computing portion 27. Combined resistance (R1+R2) is computed from the cosine component of the ratio of Vave to Iave and measured. Then leakage inductance l=l1+l2 is computed from the sin component of the ratio of Vave to Iave and measured. <P>COPYRIGHT: (C)2004,JPO |
