This solution is suitable for the products which use high-voltage rectifying method to supply the power. See the circuit as figure 7.
This circuit only consists of one choke L1, one fast switching diode D1 and one impact resistance capacitance C. The three components are used to consist of current pump circuit to replace the buffer circuit which is composed of the diode and RC network in the switching power supply.
Inductance L1 of the choking coil is four times of the lord inductance L of the switch transformer. Coupling capacitance C should be able to bear high voltage and impact, its capacity is 10 to 30nF.
The power range of the corresponding switching power supply is from 75W to 300W.
C1 capacity should be large enough to satisfy the maximum harmonic current limits, diode should be the fast recovery characteristics power diode.
This circuit should combine the principle of the active power factor correction, and use the inductive energy storage to extend the rectifier conduction time to reduce the input harmonic current range. When using this circuit, you should adjust the parameters of the switch transformer and switch transistor in order to avoid the damage of the switch transistor.
This circuit should be used in the power circuit with high-frequency power switch, large-current switch transistor, and small internal resistance.
Figure 7: Current pump type passive power factor correcting circuit