| 摘要 |
<p>A power supply including a transformer (5) having a primary winding (N1) connected to a pair of a.c. input terminals (1, 2) via a rectifier circuit (4, 4a, 4b) and a secondary winding (N2) connected to a pair of d.c. output terminals (11, 12) via a rectifying and smoothing circuit (6). Connected between a pair of outputs (43, 45) of the rectifier circuit via the transformer primary (N1), a primary switch (Q1) is turned on and off to keep the d.c. output voltage constant. Electromagnetically coupled together, two inductance coils (L1, L2) are connected to the rectifier circuit for improvements in power factor and input waveform. <??>For zero-voltage switching of the primary switch (Q1), an ancillary switch (Q2) is connected in parallel with the serial connection of the transformer primary (N1) and the primary switch (Q1) in order to provide a discharge circuit for a soft-switching capacitor (Cq1) connected in parallel with the primary switch. Switching loss is reduced by causing the soft-switching capacitor to discharge before the primary switch is turned on. <IMAGE></p> |
