Analysis and design of an isolated high step‐up converter based on the secondary side quasi‐resonant loops

Abstract

In a high step-up converter, the primary side input current contributes a significant share of total power loss. Meanwhile, high-voltage stresses of secondary side components are also big issues. This study proposes an isolated converter with secondary side quasi-resonant loops. The push-pull structure is adopted to reduce active switch numbers so the primary side power loss can be controlled in a very minor range. The newly added resonant loops on the secondary side significantly decrease the current stresses of the resonant capacitors, so the power loss caused by capacitor equivalent-series-resistance is reduced. The voltage stresses of diodes and capacitors on the secondary side are also decreased by an improved symmetricalvoltage-quadrupler-rectifier structure. The proposed converter is with the maximum voltage gain equal to 4 without consideration of the transformer. Therefore, it is helpful to decrease the transformer turns ratio. The operation process is analysed in detail and the design considerations are also summarised. Theoretical analysis is verified by the experimental results of a 400 W prototype with 34-40 V input and 380 V output.

Design and analysis of an input‐series quasi‐resonant flyback high‐voltage SMPS based on an integrated transformer

“…The quasi-resonant (QR) control of valley switching is an attractive method to improve efficiency. The QR technique controls the switching device to turn on when the drain-source voltage reaches a minimum value by utilizing the resonance generated between the inductance of the transformer and the parasitic capacitance of the switching device [26][27][28][29]. Thus it is possible to decrease the switching losses without increasing the number of other components and to achieve soft switching to a certain extent.…”

“…Bringing the above equation into (25) and eliminating the DC components and the high‐order AC components, the small signal model of an ideal flyback converter can be obtained as shown in (28) at the bottom of this page. For ease of representation, it is assumed as in (29).…”

“…Then, (28) may be presented as shown in (30). $$\begin{equation}\left\{ \def\eqcellsep{&}\begin{array}{l} {{\hat i}_{\rm{p}}}\left( t \right) = {J_1}{{\hat d}_{{\rm{on}}}}\left( t \right) + \dfrac{1}{{{R_{\rm{1}}}}}{{\hat v}_{{\rm{ds}}}}\left( t \right)\\[12pt] {{\hat i}_{\rm{s}}}\left( t \right) = {J_2}{{\hat d}_{{\rm{on}}}}\left( t \right) - \dfrac{1}{{{R_2}}}{{\hat v}_{\rm{D}}}\left( t \right) + {g_2}{{\hat v}_{{\rm{ds}}}}\left( t \right) \end{array} \right.\end{equation}$$…”

Evaluation of DC-DC converter using renewable energy sources

“…This is the technical term which refers to a class of electrical machine which is used in accomplishing the conversion from one frequency component of alternating current in to another frequency component [18]. DC supply is converted in to AC by means of rectification and then it is fed to the converter [19].Owing to the voltage step-up/step-down capability a SEPIC Converter is used for the wind energy system as well as its un-inverted output(as distinguished by conventional buck-boost converter) [20].Output Voltage has been obtained and its THD value also been determined.Figure 2 displays the simulated DC-AC Converted input [21].…”

Comparative evaluation of a family of isolated Ćuk DC/DC converter with step‐up techniques

“…Standard PWM isolated converters, such as flyback, forward, push–pull and current‐fed isolated boost, can achieve high voltage gain by increasing the turns ratio ( N ) of the transformer or increasing the duty cycle ( D ). Increasing these factors, there is an increase in the dispersion inductance, circuit wire inductance, voltage spike in the switch and diodes, high levels of current stress on the components, among others [9, 7, 15–17]. Consequently, the efficiency of these converters deteriorates.…”