The operating process of the battery adapter

(battery adapter)During the saturation conduction of switch tube VT, the DC voltage UI of C1 positive electrode is charged through L → vt → C2 positive electrode → C2 negative electrode. On the one hand, the DC voltage is established at both ends of C2, on the other hand, the magnetic energy in the energy storage inductor L is continuously increased. When the switch VT is cut off, l induces left negative and right positive voltages, and the magnetic energy in L is released to C2 and load through freewheeling diode VD. The output voltage uo of the power adapter is determined by the saturated conduction time of the VT, that is, by the base excitation pulse width. The width of the base excitation pulse is determined by the error sampling and amplification circuit.

In the series battery adapter, if there is no freewheeling diode VD, when the switch suddenly turns from saturated on to off, because the magnetic energy in l cannot be released, a very high voltage will be induced. This voltage can easily lead to the breakdown of switching tube vt. After the freewheeling diode VD is connected, when the switch turns from saturated on to off, the magnetic energy in L is released to C2 and load circuit through VD. On the one hand, the voltage at both ends of L is reduced, so that the collector emitter voltage drop of the switch is the input UI value, and there is sufficient margin; On the other hand, during the VT cut-off period, l will release energy through the freewheeling diode VD, so that the load circuit can be supplemented with energy during the switch off period, which will make the output voltage smoother and the efficiency of the power adapter higher.（battery adapter)