Robust multivariable controller design using H-infinity Loop shaping for TIFOI DC-DC converter

Abstract

A two-input fourth-order integrated (TIFOI) dc-dc converter regulates dc-bus voltage and low voltage source current with two switching devices and four energy storage elements. Each switch duty control signal in TIFOI converter system will affect the two output variables causing interactions. These interactions must be measured for proper controller structure selection. Interactions measurements may not be accurate for a converter system as some methods suggest centralized and some other suggest decentralized control schemes. So there is an ambiguity in selection of suitable controller architectures. To overcome such an ambiguity centralized interaction independent controller was designed for a TIFOI dc-dc converter using H-infinity Loop-shaping design procedure. This centralized controller is designed by combining the H-infinity robust stabilization with the classical loop shaping. This controller robustifies loop characteristics of the converter system by minimizing infinity norm associated with the set of four cost functions. The higher order controllers that resulted from the H-infinity Loop-shaping design procedure are reduced to lower order using balanced truncation model reduction. To ensure load division and bus-voltage regulation features of the TIFOI dc-dc converter are demonstrated, in simulation, on a prototype, 36 V /12 V to 24 V, 100 Watt, dc power distribution system.