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SUMMARYSeveral attempts have been made to design suitable controllers for DC-DC converters. However, these designs suffer from model inaccuracy or their inability to desirably function in both continuous and discontinuous current modes. This paper presents a novel switching scheme based on hybrid modeling to control a buck converter using mixed logical dynamical (MLD) methodologies. The proposed method is capable of globally controlling the converter in both continuous and discontinuous current modes of operation by considering all constraints in the physical plant such as maximum inductor current and capacitor voltage limits. Different loads and input voltage disturbances are simulated in MATLAB and results are presented to demonstrate the suitability of the controller. The transient and steady-state performance of the closed-loop control over a wide range of operating points show satisfactory operation of the proposed controller.

Developing efficient and appropriate modeling and control techniques for DC-DC converters is of major importance in power electronics area and has attracted much attention from automatic control theory. Since DC-DC converters have a complex hybrid nature, recently several techniques based on hybrid modeling and control have been introduced. These techniques have shown better results as compared with conventional averaging-based schemes with limited modeling and control abilities. But the current works in this field have not considered all possible dynamics of the converters in both continuous and discontinuous current modes (CCM, DCM) of operations. These dynamics are results of controlled and uncontrolled switching phenomena in DC-DC converters. This paper proposes a new switching scheme for modeling and controlling a DC-DC boost converter. The converter is represented as a hybrid automaton by considering the all three possible modes. The hybrid automaton is translated into the mixed logical dynamical (MLD) mathematical framework. The switching among these modes is generated by hybrid predictive control method which is calculated by Mixed Integer Quadratic Programming (MIQP). Using the exact model of the converter, the proposed switching algorithm can globally control the converter in all operation regimes, including CCM and DCM operations, considering all constraints in the physical plant, such as maximum inductor current and capacitor voltage limits. The switching algorithm is applied to a real converter circuit, modeled with various parasitic components. Simulation results are provided to show the advantages of the proposed control scheme. 271Several approaches have been reported in literature for modeling and control of DC-DC converters . In [24], the principles of operation of these methods are reviewed, and the shortcomings of such methods are mentioned. The main drawback of all the existing methods is that their design is based on one operating mode of operation, i.e. either CCM or DCM. Therefore, the performance and stability of the closed-loop system are guaranteed only for one operation mode.There are applications like battery powered systems [25] in which operating the converter in CCM under full load conditions and in DCM under light load conditions to improve the overall efficiency is desirable. In such cases, the operation of the converter may move from CCM to DCM or vice versa during load and line disturbances.Recently, in [26,27], several hybrid control techniques from different research groups are introduced for DC-DC buck and boost converters. However, all of these works deal with only the CCM of operation. Hybrid modeling and control of a buck converter in the MLD framework, considering all possible dynamics in CCM and DCM operation was already introduced in [24]. In this work, the same idea of modeling and control in all operation modes is extended to a boost converter. Control of a DC-DC boost converter is more difficult than buck converter. This difficulty is due to non-minimum phase dynami...