Jag hänvisar återigen till detta blogginlägg angående effekt, pris för induktionsmotorer/permanentmagnetmotor:
http://www.teslamotors.com/blog/inducti ... ess-motorsCitat:
In contrast, induction machines have no magnets and B fields are “adjustable,” since B is proportionate to V/f (voltage to frequency). This means that at light loads the inverter can reduce voltage such that magnetic losses are reduced and efficiency is maximized. Thus, the induction machine when operated with a smart inverter has an advantage over a DC brushless machine – magnetic and conduction losses can be traded such that efficiency is optimized. This advantage becomes increasingly important as performance is increased. With DC brushless, as machine size grows, the magnetic losses increase proportionately and part load efficiency drops. With induction, as machine size grows, losses do not necessarily grow. Thus, induction drives may be the favored approach where high-performance is desired; peak efficiency will be a little less than with DC brushless, but average efficiency may actually be better.
Permanent magnets are expensive – something like $50 per kilogram. Permanent magnet (PM) rotors are also difficult to handle due to very large forces that come into play when anything ferromagnetic gets close to them. This means that induction motors will likely retain a cost advantage over PM machines. Also, due to the field weakening capabilities of induction machines, inverter ratings and costs appear to be lower, especially for high performance drives. Since spinning induction machines produce little or no voltage when de-excited, they are easier to protect.
Så det kanske finns en anledning till att Toyota nu verkar satsa på induktionsmotorer. Enligt vissa rykten ett samarbete med Tesla:
http://www.torquenews.com/119/toyota-an ... ric-motorsOch Nissan Leaf ska tydligen ha en induktionsmotor:
http://nissanleafforum.com/leaf-wards.htmlBloggen avslutas med:
Citat:
Still No Winner
My conclusion is that DC brushless drives will likely continue to dominate in the hybrid and coming plug-in hybrid markets, and that induction drives will likely maintain dominance for the high-performance pure electrics. The question is what will happen as hybrids become more electrically intensive and as their performance levels increase? The fact that so much of the hardware is common for both drives could mean that we will see induction and DC brushless live and work side by side during the coming golden era of hybrid and electric vehicles.
Kontentan är väl att vid lägre effektuttag så är det fördel pm motorn, tvärtom vid högre. Fast det är kanske ingen absolut sanning. Däremot vill förstås inte Toyota vara beroende av Kinas tveksamma politik när det gäller export av de "sällsynta metaller" som PM motorerna i dagsläget kräver.