Nonminimum Phase Output Tracking Control Strategies for DC-to-DC Power Converters

Abstract

Switched mode DC-to-DC power converters [1] are used in a variety of electric power supply systems, including cars, ships, aircraft and computers. Application of Sliding Mode Control [2, 3] in tracking a real-time voltage profile is very promising because a switching control strategy is traditionally employed in power converters, and because of the inherent robustness properties of the sliding mode. Contributions to sliding mode control [2, 3] of power converters are available in many papers [l, 4, 5, 10]. Direct regulation/tracking control of the output voltage for boost and buck-boost power converters results in a nonminimum phase system and therefore an unstable controller. It has been shown in [6, 7, 9, 17, 18, 21] that controlling the current can indirectly control the output voltage in both converters. In particular, a variable unknown load was considered in [18, 21] using an optimal estimator.