Robust feedback stabilization of limit cycles in PWM DC-DC converters

Local feedback stabilization of limit cycles in PWM DC-DC converters is considered, using recently developed general sampled-data models. The paper focuses on converters for which the nominal operating condition has lost stability due to off-design operation. The results apply to stabilization of the nominal periodic operating condition. In addition, the same approach can be used to stabilize other limit cycles such as those embedded in a possible chaotic trajectory. Two feedback stabilization schemes are proposed and studied in detail. The first stabilization technique uses voltage reference compensation and the second uses dynamic ramp compensation. Both employ discrete-time washout filters to ensure preservation of the size and shape of the limit cycle. Washout filters ensure that the nominal operating branch is unaffected by the control, without the need for accurate knowledge of the limit cycle.