| 摘要 |
PURPOSE:To reduce the variation of torque in case of the changeover of the number of pulses by varying the degree of modulation lest the magnitude of the fundamental harmonic component of the output voltage of the inverter should be changed when the number of pulses is changed over. CONSTITUTION:The output of a modulation-degree control circuit 9 is controlled by the output of a pulse-number changeover circuit 12. That is, the output of the modulation-degree control circuit 9, the degree of modulation, is controlled by the pulse-number changeover command from the pulse-number changeover circuit 12, and the change of the magnitude of the fundamental harmonic component of the output voltage of an inverter 2 is prevented. Accordingly, the currents of an induction motor 3 do not alter, and torque does not vary, also. |
