| 摘要 |
PURPOSE:To raise the upper limited frequency of frequency converter by rising the gain of current control system. CONSTITUTION:Figure shows the current control circuit and phase control circuit of one phase current control system of a cross connnection mode. In the control system, the counter electromotive force compensating circuit 13 by which to make the multiplication of the magnetic flux instantaneous value signal and revolving speed signal of induction motor for calculating a signal proportional to counter electromotive force including the magnitude and phase in comply with the operating condition of motor and the impedance drop compensating circuit 14 by which to calculate a signal proportional to the impedance drop of primary winding are provided. And, the ignition phase of the frequency converter is controlled by a signal consisting of the output signal of the current control circuit 9 controlling primary winding current and the counter electromotive force and impedance drop signal. Thus, because the output of the phase control circuit becomes almost zero steadily, the apparent gain of the current control system is very higher and thus the responsibility of the primary winding current is greatly raised and the upper limited frequency of the frequency converter can be raised. |
