Switched-mode converters (one quadrant)

Switched-mode converters are DC/DC converters that supply DC loads with a regulated output voltage, and protection against overcurrents and short circuits. These converters are generally fed from an AC network via a transformer and a conventional diode rectifier. Switched-mode converters (one quadrant) are non-reversible converters that allow the feeding of a DC load with unipolar voltage and current. The switched-mode converters presented in this contribution are classified into two families. The first is dedicated to the basic topologies of DC/DC converters, generally used for low- to mid-power applications. As such structures enable only hard commutation processes, the main drawback of such topologies is high commutation losses. A typical multichannel evolution is presented that allows an interesting decrease in these losses. Deduced from this direct DC/DC converter, an evolution is also presented that allows the integration of a transformer into the buck and the buck–boost structure. This enables an interesting voltage adaptation, together with a galvanic isolation directly integrated into the converter. The second family is related to DC/DC converters with an intermediary AC stage. Such structures include middle-frequency transformers as described above, and offer reduced commutation losses thanks to natural soft commutation conditions, sometimes reinforced by the insertion of LC components or active devices. This allows high switching frequencies, and then a reduction of the size and weight of such applications.