Boundary Control of Boost Converters Using State-Energy Plane

A major consideration in designing controllers for boost converters is the existence of a right-half-plane zero in the control-to-output transfer function. This property makes the controller impossible to be designed in classical frequency-domain approach to achieve fast dynamic response over wide bandwidth of supply and load variations. In this paper, a time-domain boundary control concept for large-signal control of boost converters is proposed. By transforming the conventionally used state plane into the newly proposed state-energy plane to dictate the switching instants, a well-defined switching surface is derived. The converter can ideally revert to the steady state in two switching actions when it is subject to external disturbances. Of particular importance, experiments show that the same controller is applicable for controlling converters operating in continuous conduction mode, critical conduction mode, or discontinuous conduction mode. Sensitivities of the switching surface to parametric variations will be studied. Theoretical predictions will be verified with the experimental results of a 55 W, 48 V/110 V prototype.