| 摘要 |
PURPOSE:To avoid abnormal heat generation due to overexcitation, and to conduct smooth operation by correcting frequency so as to reduce a resistance value for arithmetically operating a primary winding together with the lowering of frequency in the torque boost control of an inverter type AC motor in which the ratio of output voltage to output frequency is increased in a low speed region. CONSTITUTION:Torque boost adjustment increasing the ratio V1/f of the output voltage of an inverter to frequency is performed for preventing the lowering of torque in an AC-motor low speed region, but overexcitation is brought at the improper ratio. A resistance value r1 for arithmetically operating a primary winding is corrected and lowered together with the reduction of frequency according to formula I in order to avoid overexcitation, thus diminishing a resistance-section voltage-drop arithmetic value, then also decreasing an inverter output V1 with the diminishing of said arithmetic value and evading overexcitation. fo represents upper limit frequency and r10 a primary-winding resistance value in 10Hz. The starting value ris of r1 and fo are determined in response to the degree of compensation. |
