Trade-offs in Sampled-data Control: a DC-DC Buck Converter Example

DC-DC power converters are often used with closed-loop control in order to be robust to signal and parametric uncertainty. Most modern control systems implement the controller digitally because of implementation and redesign flexibility. Provided the switching frequency is sufficiently high, traditional digital control methods yield acceptable designs; however, a high switching frequency is associated with higher power loss. With a view to developing more efficient power converters in the future, this paper quantifies how much we can reduce the switching frequency and still obtain acceptable performance from traditional digital control design methods and provides an alternative (based on modern "lifting" techniques) when the switching frequency is so small that the traditional methods do not yield an acceptable controller.