Method for operating switch-mode power supply with power factor correction, involves comparing current-measuring value with saw tooth signal for determining measuring time point, and determining current-middle value from measuring value

摘要

The method involves controlling switches (S1, S2) of a switch-mode power supply with operating frequency, and measuring input current (il) and output voltage per period of the operating frequency. The measurement of the current and the voltage is carried out in the middle of falling or raising flank of the input current. An input current-measuring value is compared with a saw tooth signal for determining a measuring time point, and a current-middle value is determined from the input current-measuring value, where the power supply is operated in a continuous operating condition.