Flyback topology

Finally, after all their internal checks and balance (the company was indeed fastidious in matters of product liability), they agreed they had gotten to understand the Flyback topology far better now. So I quickly incorporated the new loss term into the Mathcad and Excel... 

July 2001 We need to convert 9-14V DC to a 12V regulated output. Normally, one would use a flyback topology to achieve this. However, we would rather try to use a Boost topology with parallel 12V zener clamp diodes (for simplicity). The switcher simulations... 

In many applications it is preferable to perform PFC and isolation within a single converter stage. This is presently common in low-power requirements up to about 40 W using SEPIC and discontinuous conduction mode flyback topologies. 

The above two observations make the buck-boost topology the only pure flyback topology around, in the sense that all the energy transferred from the input to the output, must have been previously stored in the inductor. No other topology shares this unique property. 

Off-line converters are derivatives of standard dc-dc converter topologies. For example, the flyback topology, popular for low-power applications (typically <100 W), is really a buck-boost, with its usual single-winding inductor replaced by an inductor with multiple windings. Similarly, the forward converter, popular for medium to high powers, is a buck-derived topology, with the usual inductor ( choke ) supplemented by a transformer. 

Answer We must recognize that a (transformer-based) flyback topology may or may not provide us with isolation. Isolation is certainly a natural advantage accruing from the use of a transformer. But to preserve isolation, we must ensure that all the circuitry connected to the switch side of the transformer ( primary side ) is kept completely independent from all the circuitry sitting on the output side ( secondary side ). See Figure 1-1 in Chapter 1. 

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