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This paper presents new analytical equations, parametrized with respect to the number of converter phases, for multiphase isolated dc–dc topologies. This paper describes five multiphase isolated converter models, as well as their level of accuracy. Based on these new parametric models, a thorough comparative among various common high-power converter topologies is carried out, highlighting the best topology regarding efficiency, cost, and power density. The analytical results are firstly compared and verified using PLECS simulation software, and validated finally by experimental measurements with a 10-kW/20-kHz/500-V configurable laboratory prototype. Due to the low computation cost and accuracy, the developed analytical models provide important insights for optimization-based design methodologies. Furthermore, this paper highlights, depending on the targeted application and objectives, the benefits of each analyzed converter configuration. [ABSTRACT FROM AUTHOR]

A new feed-forward control technique for a dc–dc step-up converter based on the asymmetric multistage stacked boost architecture (MSBA) is proposed. The developed feed-forward controller directly handles the load current and the perturbations that may be caused by the dynamic operation of the converter. Thus, there is no time delay for estimating the error in a control process, and therefore, both robust steady-state operation and high dynamic performance can be achieved. The asymmetric MSBA dc–dc converter is a single-output high-voltage topology that embodies several in-series active voltage-balancing circuits. Thus, there is a need for an improved balancing control method. This can be accomplished by replacing the conventional proportional-integral controllers with feed-forward type and therefore improved balancing between the stages can be attained, because the steady-state errors are suppressed and the dynamic response can be enhanced. A thorough theoretical analysis is conducted for verifying the stability of the suggested feed-forward control technique in an asymmetric MSBA converter, and selective simulation and experimental results are demonstrated in order to validate the effectiveness and feasibility of the proposed control scheme. [ABSTRACT FROM PUBLISHER]

In the future, new aspects from decentralized generation using different dc voltage levels are expected to influence the general concept of power exchange. Converter are needed to adapt the voltage between low voltage (LV), medium voltage (MV), and high voltage (HV). In this paper, a galvanic isolated bidirectional dc/dc converter based on the modular multilevel converter is studied, with a large potential for secure and flexible dc power flow control. The use of medium frequency transformation allows savings in copper and iron. A fundamental frequency modulation method is introduced for the presented converter, that enables variable stepup or step-down between primary and secondary dc voltage in discrete steps. The balancing mechanism of the internal power storage components is explained and verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

Cross regulation is the main technical challenge of a single-inductor multiple-output (SIMO) dc-dc converter. This paper proposes a multivariable digital controller to suppress the cross regulation of a single-inductor dual-output (SIDO) buck converter in continuous conduction mode (CCM) operation. The controller design methodology originates from the open-loop shaping of the multi-input multi-output (MIMO) systems. The control design procedure includes: 1) determination of a family of nonparametric models of the SIDO converter at operating points of interest, 2) determination of the class of the controller, and 3) system open-loop shaping by the convex minimization of the summation of the square second norm of the errors between the system open-loop transfer function matrices and a desired open-loop transfer function matrix. The proposed controller minimizes the coupling between the outputs of the SIDO converter and provides satisfactory dynamic performance in CCM operation. This paper describes the theoretical aspects involved in the design procedure of the controller and evaluates the performance of the controller based on simulation studies and experiments. [ABSTRACT FROM AUTHOR]

This paper compares different cascaded and multilevel topologies to interface supercapacitors to a dc bus in regenerative braking applications. It is shown that the modular multilevel dc/dc converter (MMC) can benefit from both reduced voltage and increased frequency across the inductor to reduce its weight and volume when using phase shifting modulation. The proposed control method is able to balance supercapacitor voltage while providing precise output current control. The converter topology and control method are validated with simulations and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents an alternative way for the current regulation of single-phase voltage-source dc–ac converters in direct–quadrature (dq) synchronous reference frames. In a dq reference frame, ac (time varying) quantities appear as dc (time invariant) ones, allowing the controller to be designed the same as dc–dc converters, presenting infinite control gain at the steady-state operating point to achieve zero steady-state error. The common approach is to create a set of imaginary quantities orthogonal to those of the real single-phase system so as to obtain dc quantities by means of a stationary-frame to rotating-frame transformation. The orthogonal imaginary quantities in common approaches are obtained by phase shifting the real components by a quarter of the fundamental period. The introduction of such delay in the system deteriorates the dynamic response, which becomes slower and oscillatory. In the proposed approach of this paper, the orthogonal quantities are generated by an imaginary system called fictive axis, which runs concurrently with the real one. The proposed approach, which is referred to as fictive-axis emulation, effectively improves the poor dynamics of the conventional approaches while not adding excessive complexity to the controller structure. [ABSTRACT FROM PUBLISHER]

Medium-voltage conversion systems, such as traction and grid-connected converters, are continuously evolving toward higher power densities. Consequently, volume, weight, and material reductions are becoming major design issues, which lead the research focus toward high-/medium-frequency isolated power conversion systems. An optimized design of these conversion systems requires a detailed transformer-loss evaluation considering both copper and core losses. This paper presents a simple and flexible methodology to analyze global medium-frequency transformer losses in an isolated dc-dc converter fed by general nonsinusoidal waveforms. Various loss evaluation approaches are considered, pointing out their validity and limitations by means of finite-element simulations and experimental tests. [ABSTRACT FROM AUTHOR]

Focuses on a study that presented a configurable topology as front-end converter for a locomotive that can be operated as well on a high voltage alternating current (ac)-system as on a medium voltage direct current (dc) system. Multilevel chain with energy-exchange with a common dc-link via medium-frequency dc-dc converters; Configurable converter topology for multiple current systems; Experimental verification of the double-stage converter module.