| 摘要 |
PURPOSE:To suppress fluctuation of speed by switching to driving through other sound phase, upon failure of one phase converter driving an AC motor, thereby quickly generating same torque as that prevailing before failure. CONSTITUTION:When a faulty phase converter 1U is stopped, neutral points of a motor 2 and a converter 1 are connected each other, current phases of other sound phase converters 1V, 1W are modified in predetermined relation and then the firing angle is controlled according to thus modified AC current command and AC voltage command to sustain operation of the motor 2, a command for compensating the zero-phase current component flowing through the motor 2 during faulty operation is added to the AC voltage command (23) in order to compensate for the influence onto the vector control. Furthermore, terminal voltage of the motor 2 is detected until the firing angle control resumes and thus detected terminal voltage is employed, as the AC voltage command, in the control of firing angle(21, 22) thus matching the voltage phases of the converter 1 and the motor 2 and suppressing the surge current. At the same time, a predetermined current is fed quickly to the motor thus suppressing fluctuation of speed. |
