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Comment Re:A University Student's perspective on VHDL... (Score 1) 301

I back VHDL for similar, but more cynical reasons.

As a TA for my school's digital design class, we used VHDL exclusively, but I also learned a little bit of Verilog for another class. Most (all?) of the students in an intro digital design class will have used C before, and when they see Verilog they will think "oh it's just like C." But it's not, and no matter how hard you beat them over the head, half of them will never quite learn. Teach them VHDL. Half of them will hate it and curse you for years to come, but at least they have a chance of learning some hardware from it.

Comment Re:Cannot explode but can be used in cars? (Score 1) 603

Not sure what you consider to be "high" internal resistance, but one supercap example has a rated internal resistance of 0.29 mOhm. On the model I worked with (since discontinued) the rated current was about 4000 A. Not sure if that was just the rated voltage divided by the internal resistance, or if it was something lower to take heating into account.

Comment Power electronics cost money too (Score 1) 315

I wasn't expecting much, but read the article anyway and I was pleasantly surprised by the stuff they got right. And even more pissed off by the stuff they got wrong.

Yes, switching out windings at low generator speeds will tend to make it more efficient. This applies to PM machines, and could probably apply to induction machines too (though with some other issues).

However, there are many, many other things limiting the power captured from the wind besides the generator efficiency. Blade efficiency tends to drop at low wind speeds, as does the total power available from the wind (it goes with the wind speed CUBED). I'm skeptical that improving the generator efficiency will result in much change in the overall efficiency.

Also, they fail to discuss cost. Very, very few wind turbines today use permanent magnet generators. Why? They're expensive, and you need power electronics rated to the full power of the generator (say, 2 MW) to rectify the output and invert it back to AC. Power electronics of that scale are expensive too. Instead, most wind turbines use induction generators (cheaper) with power electronics controlling only the rotor currents (rated to about 30% of the total turbine nameplate rating). Until they deal with the cost issue, it's really just another trick to get a little more energy out of a PM generator.

And, speaking of energy, the author of that article needs to be locked in a room and made to write "power != energy" on the blackboard a thousand times.

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