Boost Topologies |
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Boost Topologies |
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 Watkins-Johnson Converter
This topology is really a tapped-inductor Boost Converter with a negative tap fraction. The result is a Down Converter, with two poles and a single left half-plane zero. It is thus stable without compensation, and has been used successfully to power a travelling wave tube, with its negative input impedance characteristic. The Achilles Heel of the W-J Converter is that it actually returns current to the source during D'--an extreme case of pulsating input current. The resulting noise is considerable.   Boost Converter
The Boost, or Up converter, is another unisolated topology useful on-board when a higher, rather than a lower, voltage is required. Pulsating output currents lead to noise problems, however, and feedback is difficult due to a single right half-plane zero in the control response. The converter is also widely used as an off-line preregulator in AC applications. It is then succeeded by an isolated Buck power supply. A better solution is a single isolated Cuk Converter, which does not suffer from problems of extreme complexity and high parts count. This is essentially a reliability issue.  Reverse Converter
The Boost is nearly impossible to isolate. Flyback windings can be added to the inductor to achieve multiple outputs. An isolated version was eventually contrived, but is so bizarre as to discourage employment in the field. So far as I know, it has never seen production. | Buck Converters | Boost Converters | Buckboost Converters | Further Converters | | The Four Topologies | Other Topologies | Philosophy of Design | Do the Math | | Return Home | Old Home | |
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