3 ms·
Electric motors tend to have wide useable rpm ranges, but their efficiency varies across the range, so a transmission is still useful. Scroll 2/3 of the way do
by Gracana 12y ago
Electric motors tend to have wide useable rpm ranges, but their efficiency varies across the range, so a transmission is still useful.
Scroll 2/3 of the way down this page to see a representative brushless DC motor performance curve, for example: http://www.johnsonelectric.com/en/resources-for-engineers/automotive-applications/motion-technology/ec-motor-brushless.html http://www.johnsonelectric.com/en/resources-for-engineers/au...
- mikeash 12y agoAC induction motors (typically what's used in electric cars) have a pretty flat efficiency curve. For example: http://powerelectronics.com/motion-systems/motors-efficiency-and-adjustable-speed-drives http://powerelectronics.com/motion-systems/motors-efficiency... There would be some minor efficiency gains from having multiple gears, but it's probably small enough that it would be hard to overcome the extra losses from having a more complex transmission. Note that technically electric cars do have a transmission. The motor wants to spin much faster than the tires, so you want a reduction gear to let them both live in the ranges where they're happy. It's a single-gear transmission, though, on every electric car I'm aware of.