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by WorldMaker 1537 days ago
Just about every electric vehicle at this point uses DC induction motors. Many support AC fast charging with various sorts of battery hacks, but Lithium Ion batteries are kind of inherently DC when it comes to applying power to the motors. At this point DC motors generally seem to out-class their AC counterparts other than the efficiency of using the same current as walled outlets in homes.

The article puts it this way in a bullet point toward the top:

> DC motors and appliances have higher efficiency and power to size characteristics.

3 comments

Actually, induction motors seem to be losing popularity in EVs, being replaced by permanent magnet motors which are more efficient (which also makes them easier to cool). And they're usually regarded as AC motors because they're fed 3-phase AC power from a motor controller (also called an inverter). The entire motor controller / motor system runs on DC power, so sometimes it's referred to as a brushless DC motor.

Fast charging is done with DC. Level 1 and level 2 charging uses 110 or 220 volt AC and is quite slow by modern standards.

All charging is done with DC internally. Level 1 and 2 charging uses a rectifier inside the car to convert AC to DC. Fast charging simply bypasses the rectifier.

The reason Level 2 charging is current-limited by your car -- even if you had a very high-current AC source available -- is that to take advantage of a high-current AC source your car would have to carry around a bigger, heavier rectifier. Which would decrease your EV's efficiency just by virtue of being big and heavy.

Yep, that's all true. I meant that L1 and L2 use an external AC power source.
"Brushless DC" motors are actually 3 phase AC synchronous motors with an integrated DC-> AC converter. In industrial settings with 3 phase grid power they are very efficient
Not necessarily. Brushless DC motors are not required to be 3-phase or even to use sinusoidal waveforms. Most small BDC hobby motors (such as those on drones) are not even remotely sinusoidal.
> AC fast charging

I believe you meant DC fast charging, unless you were referring to level 2 charging.

Yes, I was referring to Level 2+ charging. Some EVs can charge surprisingly efficiently that way through some interesting engineering hacks, but yes overall the industry has moved on to DC fast charging standards with "AC fast charging" a fallback.