Introduction to soft switching

Soft switching consists in using a switching aid circuit reduced to a single reactive element (series inductor for ignition or parallel capacitor for blocking) and accepting that the other switching becomes spontaneous switching.

The extreme simplicity of the switching aid circuit means that it can be placed as close as possible to the semiconductor, reducing parasitic elements and minimizing losses during controlled switching. What's more, by making the other switching spontaneous, we obtain a complete switching cycle that is theoretically lossless. Making one switch spontaneous has several important consequences:

• from a control point of view, a degree of freedom is lost (we no longer control the instant at which spontaneous switching takes place), which requires us to reconsider our energy transfer control methods;...