Analysis and design of two‐switch flyback converter with double passive lossless snubber

Abstract

A double passive lossless snubber (DPLS) is applied to a pulse width modulation two-switch flyback converter (TSFC). The DPLS, which has two capacitors, two inductors, and four diodes, has achieved zero voltage turn off and zero current (ZC) turn on for power switches without high voltage and current stresses; ZC turn on and ZC turn off for a rectifier diode without a reverse recovery problem. In this study, the steady-state operating modes of TSFC-DPLS are analysed and the proposed converter design procedure to operate in the continuous conduction mode is taken. To validate the theoretical analysis, a 240 W prototype TSFC-DPLS under an 85-135 V rms input, 24 V DC output, and 300 kHz is implemented. Finally, by utilising the experimental results, the soft switching conditions under wide input voltage and output load ranges are discussed.

High Step-Up Flyback with Low-Overshoot Voltage Stress on Secondary GaN Rectifier

“…The rectifier problem is not immensely problematic in flyback step down (for example, 240 V rms to 5 V) because the diode does not experience large voltage stress in step-down operation. Therefore, simply allowing the diode current to slowly drop to zero as in [30][31][32] is sufficient to minimize the reverse voltage problem. However, this is not the case in the high step-up flyback.…”

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…It may be easily proved, that the expression (12), with x given by ( 13) is a very good approximation for Eqn. (9) and real values of converter parameters assumed.…”

“…(9) and real values of converter parameters assumed. Taking exemplary values: R1 = 0.55 Ω, L = 170 µH, DA = 0.4, TS = 10 µs (corresponding to laboratory model of flyback used in experiments described below), one obtains: x = 0.0129 therefore the first omitted term in expansion (12) is nearly seven orders of magnitude smaller than the exact value of e -x .…”

“…Flyback DC-DC switch-mode converter is a very popular power with many applications because of its unique features such as the galvanic isolation between input and output, the wide range of possible voltage transfer function and the possibility to supply many isolated loads. The elementary descriptions of flyback converters can be found in textbooks, as for example [1][2][3], and many aspects of their properties, applications and control methods are presented in many sources, for example in [4][5][6][7][8][9][10][11][12][13].…”

A soft‐switching inverting high step‐down converter with a pair of coupled inductors and self‐driven synchronous rectifier

“…A simple approach to extend the duty cycle while maintaining a simple structure is to employ single switch isolated topologies such as Flyback and Forward converters [11,12]. In these converters, the low voltage gain of the converter can be achieved by increasing the turn ratio of the transformer.…”