Viewing profile — stevendhansen

Yes, induction machines do draw power in order to establish a magnetic field where as PM machines get it for "free" by virtue of the magnets. Also the torque production at zero spe…

You are incorrect. Induction machines are often used as generators. My employer uses them almost exclusively in the generator configuration. The Lorentz force is symmetric; in the …

Fair point about the quality of the current measurement. I probably take that for granted because I usually don't have to hit low cost targets! But that being said, a flux observer…

The high freq signal has to be lower than the switching frequency - otherwise you end up with harmonic interference from the PWM like you mentioned. For high performance servo cont…

It is not easy per-se, and yes it is used in many dissertations, but most of the limitations up to now have been more related to the performance required to implement a demodulator…

The power electronics are built using MOSFET half-bridges, which naturally support the ability to flow current in either direction. This allows current to flow from battery to moto…

Very impressive! I love to see this kind of thing on HN. I scanned through your code a bit on mobile, and here are a few quick suggestions: 1) It looks like you are using field ori…

[spoilers] The first time I read Permutation City I really enjoyed the reveal that Paul was originally a simulation (many times over) that only existed in the "real" world because …

Seconded, Blindsight is one the best SF books I've ever read. "Imagine you are Siri Keeton..." Can't wait for the 3rd book (Omniscience I think?) to come out.

Expansiveness in that Three Body Triology takes place over a large period of time (billions of years), and the fact that it takes place over such a large space (Earth, Trisolaris, …

Robert Zubrin has discussed the "moon first" strategy, and has made the interesting observation that many of the pro arguments come from entrenched space industries looking to make…

Different strokes I guess. I really enjoyed the Three Body Problem trilogy due its expansiveness both in time and in space, and its focus on ideas rather than (solely on) character…

There has been some good discussion on Reddit about how the thrust results shown in the paper are still most likely measurement errors due to thermal effects. It is a shame that th…

Well said.

With respect, the idea that most parents could fix the system if they just tried is incredibly naive. I think most parents do the best that they can. If they feel that homeschoolin…

The big problem in my mind is that Python is the wrong tool for the job. It is 2016, there are more hard-RTOS prototyping platforms than ever before. My favorite is National Instru…

I have a guess: the limit in these designs isn't typically the motor, but instead the power semiconductors in the inverter (the motor has a much longer thermal time constant than t…

As pointed out in other comments Tesla actually uses AC induction machines (asynchronous AC) instead of brushless machines (synchronous AC). To a first approximation an AC inductio…

Except it isn't just the spread of misinformation. Even more important (IMHO) is the insulating effect of showing people only like-minded opinions, effectively trapping everyone in…

"...until you can come to a consensus that's acceptable to everyone." In my (admittedly anecdotal) experience, democracy rarely seeems to come to any consensus that is acceptable t…

Reminds me of a book I recently finished (Death's End by Cixin Liu). A major plot element is sending a human brain to intercept an alien civilization that is en-route to Earth with…

"our radically capitalist regime" Citation required. I'd venture the US is more accurately described as a hybrid socialist / mercantilist regime than a capitalist regime.

It can be both.

The only alternatives to privatization I can see are: 1) force the population to collectively pay for these services or 2) force specific individuals to provide these services for …