Sinusoidal AC=DC voltage converter with primary-switched transformers

摘要

The primary windings (UW11,UW12) of both transformers (T1,T2) are connected alternately in parallel with the power switch (LS) by respective switches (US1,US2) operated by a flip-flop (FF). The secondary currents are rectified by diodes (D1,D2) producing DC which is smoothed by a common capacitor (GC). Each transformer has a demagnetising auxiliary winding (HW1,HW2) in opposition to its primary and in series with another diode (HD1,HD2) drawing only about 10% of the primary current. The single control unit (PFC) provides a pulse of adjustable width for the power switch. The DC voltage (U2) across the smoothing capacitor is measured by a monitor (LSU) and fed back through an opto-coupler (OK) to the control unit.