JPS6233802B

An efficiency factor increasing circuit for cascade rectifier circuitry supplying d.c. motors, applies to electrical vehicles and matching speed to current etc. The unit comprises a transformer with one primary and several secondaries. Bridge rectifiers are connected to each secondary and then connected in cascade. A circuit is connected to the bridge rectifiers and is controlled by phase regulating and primary current/voltage monitoring circuitry. The efficiency factor improvement circuitry is immune to spurious oscillations and instantaneous high voltages on the transformer. A switching circuit (LD1,OS) with input from a current transformer (CT) on the transformer primary (Tr N1) controls the efficiency factor improvement circuit (CLCA) to connect it with the secondary (N22) and bridge rectifier (Rf2) when the primary current has reached a predetermined value. The phase monitoring units (F1,C1,F2,C2,GA) disconnect the improvement circuit (CLCA) using a flip-flop (FF) at certain phase relationships of primary voltage and current. The bridge rectifiers (Rf1, Rf2) are not phase regulated at the same time so that one is regulated whilst the other is at its highest output level.