Commutation similarity

Electric Motors and Controllers
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Ianhill   10 MW

10 MW
Posts: 2240
Joined: Sep 25 2015 5:55pm

Commutation similarity

Post by Ianhill » Apr 06 2021 4:55pm

Ive been studying motor commution in my spare time and ive noticed that a true sinewave run bldc motor is very simular output to a brushed motor in how the field coils energize even though the signals they see are different.

Bldc frequency based sineasolodal wave.
Field energises with a typical rounded curve.

Brushed motor pwm based signal.
But heres where the magic happens as the rotor turns the brushes swipe the commutators so even though its signal is digital on off pwm the rotor smoothes that out depending on the commutator and brush assembly arrangment this can be manipulated.

Timing retard and advancment on the brush assembly can change the motor characteristics and bldc achieves this virtually on the fly in some cases phase advance or retard and the output speed and torque are manipulated in this way brushed motors needed to be manually tuned by hand for this feature.

Now there's FOC becoming matured enough to make it into mainstrem controllers and motor design is far from brushed motors i think we are getting close to small compact drivetrains with a massive bite.

Batterys are the next step on the chain oncr thats cracked the world of DIY personal ev is going to be full of high power mental rides.

Please feel free to comment correct or add to the topic.

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