| 摘要 |
<p>A three-phase attenuator output is rectified by three diodes (21, 22, 23) on the positive side and three thyristors (25, 26, 27) on the negative. A blocking diode (24) is connected across the output together with a buffer resistance (29) and a shunt (28) in series with the load. Saw-tooth generators (41, 42, 43) are supplied from a synchronisation generator (44) which produces a control voltage (44a) proportional to the frequency of the synchronisation pulses, and three pulse outputs (at 44b, 44c, 44d) derived from photocouplers (46, 47, 48) comprising electroluminescent diodes and phototransistors. The sawtooth generators outputs are connected to comparator circuits (37, 38, 39) fed with signals from summator (51) and amplifier (55), and controlling the firing of the thyristors through pulse generators (34, 35, 36) and transformers (31, 32, 33).</p> |
