| 摘要 |
PURPOSE:To eliminate insufficient torque by judging whether it is power drive or a generative drive by a mode discriminator and automatically correcting the impedance drop in response to the operation mode when a current increases, thereby always maintaining an exciting magnetic flux constant. CONSTITUTION:A polarity adding circuit 15 produces the output of an absolute circuit 14 as positive polarity by the output of a mode discriminator 13 at power drive time and the absolute value output as negative polarity at regenerative drive time. A correcting voltage outputting circuit 12 outputs a voltage to be corrected. Thus, even if a current increases due to a load, since the output voltage is corrected to be added in the power drive mode and to be subtracted in the regenerative mode, insufficient torque due to the reduction in the exciting magnetic flux at power drive heavy load time can be eliminated, and an overexcitation phenomenon can be avoided at the regenerative heavy load time. |
