| 摘要 |
PURPOSE:To prevent the secondary overvoltage at the recovery time by switching the current reference of a converter provided at the secondary side from the reference at the operating time to the current reference, to which delay current is flowed substantially equally to the primary exciting current at the instantaneous power interruption time. CONSTITUTION:The secondary side of a wound-rotor induction motor 1 is connected through converters 2-4 to an AC power source, the returning amount of the secondary power to a power source is controlled, thereby driving the motor 1 at variable speed. It is compared with the converter current I with the operating current reference I 0 as a reference through a current reference switching circuit 36 at the normal time, thereby controllig the power inverter 4 at the normal time, it is detected by a detetor 21 at the instantaneous power interruption time to switch the circuit 36, thereby controlling by the current reference I P set by a setter 38. Accordingly, the value of I P is set to cancel the exciting current flowed to the primary side of the motor from a phase advancing condenser 7, thereby suppressing the overvoltage of the secondary voltage produced when recovered. |
