Abstract: A high power factor AC to DC power supply having a high frequency pulse producing circuit comprising an inductor supplied with rectified raw AC power through a semiconductor switch which provides dynamic power factor correction by maintaining the width of the on-times of the switch substantially constant throughout each cycle of the input AC power. The peak energy stored in the inductor during the on-times are a function of the amplitude of the instantaneous voltage of said rectified AC power, so that each time the switch is turned off, the output pulse of current supplied to the load by the inductor has a time duration which is a direct function of the instantaneous voltage value of the rectified AC power. The output load has a filter whose time constant is greater than a cycle of said rectified AC power, and the average on-time of said switch is varied over a number of cycles of said AC power to regulate the output voltage of said supply.

Abstract: A preregulator power supply having drive and control circuits which are isolated or floating alternately from the input and output leads to permit direct coupling to the power switching regulator device without requiring isolation devices such as transformers or optical isolators. This is achieved by an added series winding on the output choke, the common junction of which is connected to the output of the switching regulator and also forms the return lead for the floating drive and control circuits, while the added winding provides a sample output voltage for comparison by the floating drive and control circuits to control the width of pulses fed to the switching regulator device. A free-wheeling diode is also connected from the output of the switching regulator to an output terminal to maintain current in the choke during the OFF cycle of the switching regulator and provide several isolated regulated voltages in windings magnetically coupled to the choke.