A control circuit is configured to sense an AC input voltage of a power factor correction (PFC) power circuit in a switching power converter, provide a control signal having an on-time and an off-time to at least one power switch of the PFC power circuit, and in response to detecting a peak voltage of the AC input voltage, increase the on-time of the control signal based on the sensed AC input voltage during an interval that begins with the peak voltage of the AC input voltage and ends with the next zero crossing following the peak voltage of the AC input voltage to improve a power factor of the switching power converter. Other example switching power converters, PFC power circuits and control circuits for controlling one or more power switches are also disclosed.

A control circuit is configured to sense an AC input voltage of a power factor correction (PFC) power circuit in a switching power converter, provide a control signal having an on-time and an off-time to at least one power switch of the PFC power circuit, and in response to detecting a peak voltage of the AC input voltage, increase the on-time of the control signal based on the sensed AC input voltage during an interval that begins with the peak voltage of the AC input voltage and ends with the next zero crossing following the peak voltage of the AC input voltage to improve a power factor of the switching power converter. Other example switching power converters, PFC power circuits and control circuits for controlling one or more power switches are also disclosed.

A method for power conversion includes coupling a first string to a second string via a first connecting node and a second connecting node to form at least one leg of a power converter. The first string is operatively coupled across a first bus and a second bus and comprises a first branch and a second branch coupled via a third connecting node. The first branch and the second branch include a plurality of controllable semiconductor switches. Furthermore, the second string comprises a first chain link and a second chain link coupled via an alternating current phase bus and includes a plurality of switching units. The first chain link and/or the second chain link are controlled to generate a negative voltage across at least one of the plurality of controllable semiconductor switches during a switch turn off process.

A method for power conversion includes coupling a first string to a second string via a first connecting node and a second connecting node to form at least one leg of a power converter. The first string is operatively coupled across a first bus and a second bus and comprises a first branch and a second branch coupled via a third connecting node. The first branch and the second branch include a plurality of controllable semiconductor switches. Furthermore, the second string comprises a first chain link and a second chain link coupled via an alternating current phase bus and includes a plurality of switching units. The first chain link and/or the second chain link are controlled to generate a negative voltage across at least one of the plurality of controllable semiconductor switches during a switch turn off process.