CONSTANT MARGINAL ANGLE CONTROL SYSTEM FOR MULTISTAGE CASCADE THYRISTOR CONVERTER

摘要

PURPOSE:To eliminate the commutation failure even when a commutation superposing angle abrupt varies by temporarily increasing the set value of the marginal angle immediately before switching when a unit converter is switched between a through operation and an inverter operation. CONSTITUTION:Semiconductor unit converters 40-44 are respectively connected to the secondary windings 31-35 which are divided in multiple number to delete the harmonic current at the current side of a main transformer 3 which inputs from an AC power source 1, are connected in cascade to each other to a main converter. The armature 5 of a DC motor is connected to the main converter through a smoothing reactor 2. The set value of the marginal angle is temporarily increased immediately before switching when the converters 40-44 are switched from the through operation to the inverter operation or vice versa.