Search

A reconfigurable gain circuit is proposed for an LCLC resonant converter with bidirectional capability considering wide varying redox flow battery source. A suitable hybrid control scheme for LCLC resonant converter with secondary synchronous rectifier is proposed in this work. The proposed reconfigurable circuit enables to configure secondary bridge as an active voltage doubler, full-bridge circuit during forward power transfer mode and reverse power transfer mode, respectively. The reconfigurability helps significantly to design a transformer with lower secondary turns and achieve desired high gain. The reduced transformer secondary turns result in reduced transformer parasitics. The presence of LCLC resonant tank helps to provide the additional gain; the hybrid control scheme ensures zero-voltage switching turn-on for the primary, and secondary synchronous mosfets throughout the operating range. The proposed converter is analysed using fundamental harmonic approximation. The proposed reconfigurable gain circuit and hybrid control scheme is verified experimentally for an 800 V/1 kW hardware prototype fed from 24 to 54 V input. [ABSTRACT FROM AUTHOR]

A novel auxiliary switch dc-dc converter with coupled inductor is presented in this paper. The proposed circuit achieves loss-less switching for both the main and auxiliary switches without increasing the main device current/voltage rating. A tapping in the pole inductor is added for the purpose of commutation. The proposed circuit is capable of operation at elevated switching frequencies of several hundreds of kHz, in a range of line and load variations. The proposed circuit is applicable to all isolated and non-isolated dc-dc converters. The performance and the design equations of the ZVS are identical for all types of dc-dc converters when the throw voltage and the pole current are properly defined. In the sections that follow, operating principle and theoretical analysis of the proposed circuit is outlined through the example of buck converter. Simulation and experimental results of 33 W,400 kHz boost converter are presented. Index Terms--Auxiliary switch converters, coupled inductor, resonant converters, zero current switching (ZCS), zero voltage switching (ZVS).

In this article, we focus on the analytical modeling of nonisolated single-input multiple-output (SIMO) dc–dc converters governed by linear differential algebraic equations (DAEs). The modeling challenge in nonisolated SIMO converters arises due to the switching among multiple DAEs governing the circuit. Averaged models of such converters, described by an ordinary differential equation, are derived using the notion of quasi-Weierstrass transformation. Using this technique, we derive the averaged model for a nonisolated Zeta–Buck–Boost (ZBB) converter. It is observed that the dynamics of the state variable corresponding to the algebraic constraint is uncontrollable and eliminating this state leads to a fourth-order completely controllable averaged model. This model is used to design a linear state-feedback controller for line regulation. In the case of bipolar SIMO converters, ZBB being an example, regulation of the two outputs can be achieved using any one of the two output integral states. Although the state-feedback controller successfully rejects the disturbance asymptotically, it is found that the deviations from the set point in the transient phase can be large. To see if smaller deviations can be achieved by appending the linear controller with a nonlinear term, we explore a nonlinear controller based on the Lyapunov redesign technique. Smaller deviations with complete disturbance rejection are possible if the disturbance is matched. When it is unmatched, small deviations are achieved at the expense of steady-state errors, whose estimate is explicitly found. The proposed model and control scheme are verified through a laboratory built hardware prototype. [ABSTRACT FROM AUTHOR]