A. Nemati, M. Pakdel,
Volume 6, Issue 3 (9-2010)
Abstract
A novel ZVZCS isolated dual series-resonant active-clamp dc–dc converter is
proposed to obtain high efficiency. The proposed converter employs an active-clamp
technique, while a series-resonant scheme controls the output voltage with the complementary
pulse width modulation controller. The active-clamp circuit serves to recycle the energy
stored in the leakage inductance or the magnetizing inductance and provides zero-voltage and
zero-current turn-on and turn off switching. The voltage stresses of the main switch are
clamped. The voltage transient spikes across the dual series active clamp circuit and the
current stress of the current-fed side switches are limited by auxiliary active clamping circuits
on both sides, and ZVZCS is achieved. The operating principles and design considerations are
discussed and verified by simulations using PSIM software. Also, the EMI reduction
techniques from EMC point of view in the circuits related to converters has been pointed out.
A. Vahedi, A. Baktash,
Volume 11, Issue 1 (3-2015)
Abstract
Recently, tape wound cores due to their excellent magnetic properties, are widely used in different types of transformers. Performance prediction of these transformers needs an accurate model with ability to determine flux distribution within the core and magnetic loss. Spiral structure of tape wound cores affects the flux distribution and always cause complication of analysis. In this paper, a model based on reluctance networks method is presented for analysis of magnetic flux in wound cores. Using this model, distribution of longitudinal and transverse fluxes within the core can be determined. To consider the nonlinearity of the core, a dynamic hysteresis model is included in the presented model. Having flux density in different points of the core, magnetic losses can be calculated. To evaluate the validity of the model, results are compared with 2-D FEM simulations. In addition, a transformer designed for series-resonant converter and simulation results are compared with experimental measurements. Comparisons show accuracy of the model besides simplicity and fast convergence