| 摘要 |
PURPOSE:To measure the offset of a current detector under the state in which an AC motor is supplied with currents from a power converter, and to compensate offset by making output currents flow only through the two phase of the AC motor, detecting the output currents of the other phase and controlling the power converter. CONSTITUTION:A current detector 4U detecting the currents of the U phase of an induction motor 2 is installed on the output side of a PWM inverter 1 and a current detector 4W to W phase respectively, and a coordinate converter 16 is supplied with currents through adders 17, 18. When the output voltage of the PWM inverter 1 is used as a voltage vector orthogonal to the U phase, excitation currents fed to the induction motor 2 are made to flow only through V phase and W phase. When the detecting signal of the current detector 4U of the U phase is not brought to zero, the magnitude of the detecting signal is employed as the offset of the U-phase current detector 4U, and offset is compensated through an offset regulator 6. Accordingly, the generation of the torque ripple of the induction motor 2 can be prevented. |
