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Comment by esmi | Hacker News Reader

I was shocked to see the title because I thought forward converters were invented in the 70s but it turns out they were invented in the 50s with some early examples in the 20s, if one gets loose enough with the definition of “converter”.

https://pdfs.semanticscholar.org/0911/34a5dc72c5a363ec937e40...

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Yes, these converters go way back, although the AGC used a buck converter not a forward converter. They became more practical in the 1970s as transistor technology improved. I wrote a history of power supplies in the IEEE Spectrum recently: https://spectrum.ieee.org/computing/hardware/a-half-century-...

Nice article thanks for sharing it. What definition are you using for forward converter? The definition I always use, which I thought I got from Erickson’s Fundamentals of Power Electrons, is any topology where the inductance is charged in series (as opposed to parallel like a boost or fly back) with the load. I’ve always liked this definition because it still conveys critical meaning even when engineers do trivial topology changes from the “standard” forward converter topology.

I've seen a forward converter described as buck-derived, or buck with a transformer, but buck converters and forward converters are generally viewed as two separate things. I'm not too attached to definitions but I consider a forward converter as using a transformer and transferring energy while the switch is on. This is the definition used by the article you linked to, and by Wikipedia for Forward Converter. I also like the TI poster of power topologies: https://www.ti.com/lit/sg/sluw001f/sluw001f.pdf

I think the article I linked to didn’t require the transformer. Only that there be transfer with the switch on which implies the series connection. :) Wikipedia certainly does though and honestly, especially in power conversions, there’s not a lot of standardization in terms which is why I asked. I’m not too hung up on the definition either. I’m probably just over sensitive because all the marketing material I’m asked to review...

I have a 1926 book "Alternating Current Rectification" which describes a large (room-sized) DC-DC converter for an industrial application. It used rotating commutators to switch the current synchronously on both sides of a transformer. That's essentially a forward converter.

The book was written from the point of view that rectification was pretty much all figured out and it was just a question of some more tweaking and miniaturizing.

Also, 1930s-1950s car radios typically had a step-up converter from the battery voltage to the plate voltage which was a vibrating relay connected to a transformer with diodes to rectify the output.

[0] https://www.amazon.com/Alternating-current-rectification-all...

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