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Don't DC-DC transformers use AC internally?
by na85 5y ago
Don't DC-DC transformers use AC internally?
- dreamcompiler 5y agoYes but it's kHz-range PWM square-wave AC; there's no 60Hz sinewave involved. Converting to/from a 60Hz sinewave requires extra circuitry that decreases efficiency. And in this application a 60Hz AC sinewave serves no useful purpose.
- jagger27 5y agoThe point is to remove the laptop power brick. Let's say the laptop charger is 90% efficient, which is fairly typical. The post claims their 12VDC to 240VAC inverter is 92% efficient. A 12VDC to 20VDC voltage booster would only have to be >83% efficient to beat that setup.
- colejohnson66 5y agoWhich isn’t that hard for a switch mode converter. Those are usually 85% or more IIRC.
- reportingsjr 5y agoIn power electronics terms, no. AC is defined as waveforms that have an average value of zero, which you won't find in a DC-DC converter. That wasn't the point of OP though. Their point was that you could remove some inefficient steps to improve the overall efficiency and energy capture of the system.
- 0xfaded 5y agoNot necessarily. See voltage doubler: https://en.m.wikipedia.org/wiki/Voltage_doubler https://en.m.wikipedia.org/wiki/Voltage_doubler
- jmrm 5y agoIf you want electrical isolation between the input and the output, they use AC in the middle to achieve that, but if you don't want isolation, you could use a boost DC converter: https://en.wikipedia.org/wiki/Boost_converter https://en.wikipedia.org/wiki/Boost_converter
- nomel 5y agoWhich use alternating voltage, across the inductor, but the current is always (with load) positive. Neat!