Inverter firing angle control system - uses multipliers for three phases of AC supply and multiplier for DC line connected to output multiplier pair

摘要

The firing angle control system for an inverter has three multipliers (11,12,13) for the three phases of an a.c. supply. They are connected by ohmic resistances (7,8,9) to an amplifier (22) in parallel with another multiplier (16). A line for a d.c. supply for a nominal value current flow, is connected by a further multiplier (14) and an ohmic resistance (3) to another amplifier (21) and a further multiplier (15) in parallel with it. The two amplifiers are interconnected by the respective final multipliers (15,16), and a further ohmic resistance (5) to a differential amplifier (23). The negative input of this amplifier is connected to the junction point between two multipliers (17,18). One multiplier (17) is connected to the amplifier output and the output connection, and the other multiplier (18) is connected to the negative input of the amplifier and its input resistance (5). The a.c. voltage is attenuated without a delay, or is amplified with a heavy delay.