Abstract: A buck-boost power conversion circuit comprises a first active switch, a second active switch, an inductor, a center-tapped current transformation element, and a signal rectification unit. The first active switch is cascaded to the second active switch, which is connected in parallel with a power source. The inductor is connected with a capacitor. The center-tapped current transformation element includes a primary winding and a secondary winding. The primary winding are connected with the first and second active switches. The primary winding includes a tapped terminal connected with the inductor. While the first or second active switch is turned on, the primary winding supplies power to the inductor through the tapped terminal, and the secondary winding is induced magnetically to generate a magnetic induction signal. The signal rectification unit is connected with the secondary winding, receiving and rectifying the magnetic induction signal to generate a current sensation signal.

Abstract: A boost converter circuit able to sense current comprises an inductor connected with a power source; an active switch; a passive switch; a capacitor connected with one end of the passive switch, which is not connected with the active switch; a center-tapped current transformation element; and a signal rectification unit. The center-tapped current transformation element includes a primary winding and a secondary winding. Two ends of the primary winding are respectively connected with the active switch and the passive switch. The primary winding is connected with the inductor through a tapped terminal. The secondary winding is magnetically induced by the primary winding to generate a magnetic induction signal while the primary winding receives an inductor current. The signal rectification unit is connected with the secondary winding, receiving the magnetic induction signal and rectifying the magnetic induction signal to generate a sensed current signal corresponding to the inductor current.

Abstract: A totem-pole power factor correction circuit (totem-pole PFC) is connected behind an input inductor receiving electric power from an alternating current (AC) power source. The totem-pole PFC is provided, in a high-frequency working area thereof, with at least two current transformer elements or a center-tapped current transformer element. The waveform of current flowing through the totem-pole PFC during positive and negative half cycles of AC power is sensed via the current transformer elements or the center-tapped current transformer element. Thereby, current waveform for the input inductor during positive and negative half cycles may be realized via the obtained current waveform completely, such that the practical problems originating from the conventional necessity for the establishment of bulky Hall device or another current-sensing unit are solved specifically.