| 摘要 |
<p>A switching power supply unit comprises a series circuit connected to both ends of a DC power supply (Vdc1) and composed of a reactor (L3), the primary winding (5a) of a transformer (T), and a switch (Q1), a series circuit connected to both ends of the primary winding and composed of a switch (Q2) and a clamp capacitor (C3), a saturable reactor (SL1) parallel connected to the primary winding, a rectifying/smoothing circuit (D1, D2, L1, C4) for rectifying and smoothing the voltage induced in a secondary winding (5b), and a control circuit (10) for alternately turning on/off the switches (Q1, Q2) and turning of the switch (Q2) by the saturation of the saturable reactor (SL1) when the current of the switch (Q2) increases. The reactor (L3) is composed of a leakage inductance between the primary and secondary windings. The primary winding of the transformer (T) is divided into two parts, and the two parts are connected in series. The secondary winding is provided between the two parts of the divided primary winding. The numbers of turns of the two parts are changed to adjust the leakage inductance. Thus, the saturable reactor (SL1) is saturated.</p> |
