Linear-nonlinear control applied to buck converters to get fast transient response

To feed the latest generation of microprocessors and DSP is one of the main challenges for power supply designers. Both high current slew rates together with low output voltage are required. Firstly, the designer tries to comply with previous requirements optimizing the power stage and the control loop bandwidth, but if it is not enough then new strategies are needed. In this paper, a novel control technique is presented. The proposed combined linear-nonlinear control (LnLC) increases significantly the capability of a conventional linear control to reduce the recovery time of the output voltage drop produced when a load current step occurs. Experimental results have been obtained for two cases: a synchronous rectifier buck converter, with a conventional voltage loop and the same converter with the novel LnLC. The comparison of these experimental results validates the proposed idea.