1. Hysteretic and sliding modes

Linear voltage or current control of a switching converter requires an output filter of sufficient size to limit output voltage ripple, i.e. a large-value capacitor. The current trend is to reduce the size of this capacitor without sacrificing static performance (output voltage ripple, energy efficiency) or dynamic performance. Control strategy plays an important role here, as does converter topology, such as phase multiplication and phase interleaving. With fixed-frequency modulation, the lower the frequency, the more imposing the filter. This is because the corrector needs several switching periods to react to a disturbance. In addition to a long reaction time, the output voltage will undergo a more pronounced variation, as the corrector takes time to correct the energy level in the inductance. To limit this amplitude of variation, there's no other way than to increase the size of the...