| 摘要 |
The drive for thyristors (V1, V2), which are connected in reverse parallel, of an AC controller supplying a transformer load (T) is intended to be ensured by means of continuous control pulses (iSV1, iSV2) which can be displaced by phase gating of the applied AC voltage (U AC), for all operating modes with trigger-pulse transformers which are as small as possible and losses in the control circuit which are correspondingly small. For this purpose, the length of each control pulse (iSV1, iSV2) is kept constant up to a phase gating angle having a control angle of 90 DEG (calculated from the zero crossing of the AC voltage (U AC) on the respective thyristor (V1, V2)), and each control pulse (iSV1, iSV2) is terminated, in the case of control angles of more than 90 DEG , at 270 DEG of the AC voltage period. <IMAGE>
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