Inductor losses estimation in DC-DC converters by means of averaging technique

A suitable inductor modeling for power electronic DC-DC converters is presented in this paper. It is developed with the aim of improving inductor losses estimation achievable by averaged models, which inherently neglect inductor current ripple. In order to account for its contribution to the overall inductor losses, an appropriate parallel resistance is thus enclosed into the inductor model, whose value should be chosen in accordance with the DC-DC converter operating conditions. This allows the development of improved averaged models of DC-DC converters, especially in terms of power losses estimation. The effectiveness of the proposed modeling approach has been validated through a simulation study, which refers to the case of a boost DC-DC converter and is performed by means of a suitable circuit simulator designed for rapid modelling of switching power systems (SIMetrix/SIMPLIS)

A Novel Continuous-Time Equivalent Circuit for Boost DC-DC Converters

A novel continuous-time equivalent circuit suitable for boost DC-DC converters is presented in this paper. It has been developed on the basis of the averaging technique with the aim of achieving a good ripple-free representation of the state variables of the system, whatever the converter operating mode is, i.e. Continuous Conduction Mode (CCM) or Discontinuous Conduction Mode (DCM). This goal can be achieved on condition that an appropriate PWM pattern is introduced, which enables an almost perfect matching between state variables and their corresponding equivalent ones at the start of each sampling time interval. Apart from the inductor and the capacitor, the proposed circuit consists of some equivalent input voltage and output current sources, together with several constant and/or variable resistors, which depend on converter switching signals and circuital parameters. The proposed continuous-time equivalent circuit has been validated through a simulation study, which is performed by means of the software PLECS. Simulation results highlight the worth and the effectiveness of the proposed modelling approach, over both transient and steady state operations

Modellistica e progettazione di convertitori elettronici di potenza DC-DC

The present PhD dissertation deals with average modeling, design and experimental verification of power electronic converters. This takes the DC-DC Boost converter as a reference, together with some converter topologies derived from it, such as the interleaved PFC Boost converter. More specifically, in the first part of the dissertation DC-DC converters fundamentals are briefly introduced, i.e. their operating mode, their basic circuit topologies and their parallel and series connections, as well as the basic problems inherent to the design stage of DC-DC converters. Subsequently, this PhD dissertation focuses on the mathematical modeling of the Boost DC-DC converter by means of the averaging technique. In particular, appropriate equivalent switching signals are introduced in order to take into account each converter operating state properly, together with the switch commutation phenomena. In addition, a suitable inductor model is introduced in order to improve inductor losses estimation. As a result, the proposed averaged models are dependent on the switching frequency, still preserving a ripple-free representation of the state variables of the system. The proposed averaged modelling approach enables an enhanced power losses estimation by accounting for switching and current ripple phenomena, over both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). The worth and effectiveness of the proposed modelling approach has been validated through several simulation studies, which are performed in the Matlab-Simulink and SIMetrix/SIMPLIS environments. The last part of this thesis the Boost PFC converters and new silicon carbide power devices, already available in the market, is provided. In particular, with a constant increase of the switching frequencies and the converters power density, new and most efficient solutions are required, for both circuit topologies and power semiconductors. In this context is presented an extensive experimental analysis of a two-phase Interleaved PFC Boost converter. It aims to highlight the most important features of two-phase interleaved PFC converter operation, in terms of both performances and electromagnetic compatibility issues. This has revealed a low level of harmonic pollution and an excellent result in terms of efficiency at rated load, but also potential conducted EMI issues within low and medium frequency ranges. Efficiencies, switching frequencies and operating temperatures, even in these circuit topologies, are strongly dependent on the power electronics devices used. For this reason it has been dealt an experimental study on the silicon carbide semiconductors. Experimental results are finally reported and discussed; they shown that the reduced power dissipation and the low impact of the parasitic elements, that characterize such semiconductor devices, make these components an interesting solution in the realization of compact and highly efficient energy conversion systems

Modellistica e progettazione di convertitori elettronici di potenza DC-DC

The present PhD dissertation deals with average modeling, design and experimental verification of power electronic converters. This takes the DC-DC Boost converter as a reference, together with some converter topologies derived from it, such as the interleaved PFC Boost converter. More specifically, in the first part of the dissertation DC-DC converters fundamentals are briefly introduced, i.e. their operating mode, their basic circuit topologies and their parallel and series connections, as well as the basic problems inherent to the design stage of DC-DC converters. Subsequently, this PhD dissertation focuses on the mathematical modeling of the Boost DC-DC converter by means of the averaging technique. In particular, appropriate equivalent switching signals are introduced in order to take into account each converter operating state properly, together with the switch commutation phenomena. In addition, a suitable inductor model is introduced in order to improve inductor losses estimation. As a result, the proposed averaged models are dependent on the switching frequency, still preserving a ripple-free representation of the state variables of the system. The proposed averaged modelling approach enables an enhanced power losses estimation by accounting for switching and current ripple phenomena, over both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). The worth and effectiveness of the proposed modelling approach has been validated through several simulation studies, which are performed in the Matlab-Simulink and SIMetrix/SIMPLIS environments. The last part of this thesis the Boost PFC converters and new silicon carbide power devices, already available in the market, is provided. In particular, with a constant increase of the switching frequencies and the converters power density, new and most efficient solutions are required, for both circuit topologies and power semiconductors. In this context is presented an extensive experimental analysis of a two-phase Interleaved PFC Boost converter. It aims to highlight the most important features of two-phase interleaved PFC converter operation, in terms of both performances and electromagnetic compatibility issues. This has revealed a low level of harmonic pollution and an excellent result in terms of efficiency at rated load, but also potential conducted EMI issues within low and medium frequency ranges. Efficiencies, switching frequencies and operating temperatures, even in these circuit topologies, are strongly dependent on the power electronics devices used. For this reason it has been dealt an experimental study on the silicon carbide semiconductors. Experimental results are finally reported and discussed; they shown that the reduced power dissipation and the low impact of the parasitic elements, that characterize such semiconductor devices, make these components an interesting solution in the realization of compact and highly efficient energy conversion systems