Single-stage APFC technology is combined with a
DC/DC circuit power factor correction circuits together,
sharing power switch tube, and only with a control circuit.
Control circuit's role is to achieve control of the output
voltage, stabilized DC output voltage, power factor
correction circuit is not controlled. Thus, PFC level must
have an intrinsic PFC function, that is, in the case of control of the active power factor correction, input currents could
be fully or substantially follows the sine of the input voltage
changes. It is well known that at the time of a fixed duty
cycle, Boost transform has inherent in DCM mode PFC
function. Figure 1 for single level PFC transform Manager
of topology structure figure, it usually by Boost transform
Manager and DC-DC transform Manager constitute,
transformers front-end can as a Boost transform Manager,
and Boost circuit itself has regulation PFC of features, can
obtained higher of power factor, General in 95% above, so
this circuit of power factor higher, through control switch
tube of opened and closed broken, thus achieved on entered
current of plastic and output voltage of regulation