in DC machines, how do commutators convert induced AC voltage into DC ?
in DC machines, how do commutators convert induced AC voltage into DC ?
(OP)
Hello guys
I have been reading about DC machines and I read that commutators are responsible for converting AC to DC voltage
my question is:
how do commutators convert induced AC voltage into DC exactly ?
I have been reading about DC machines and I read that commutators are responsible for converting AC to DC voltage
my question is:
how do commutators convert induced AC voltage into DC exactly ?





RE: in DC machines, how do commutators convert induced AC voltage into DC ?
bad book.. Commutator just use DC voltage for making rotating field and operation of DC motors.
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
The commutator is simply a fancy multi-pole switch. When the AC is in let's call it the "positive" phase, that fancy switch connects that phase on the rotor to the "positive" DC brush and the opposite phase somewhere else on the rotor to the "negative" brush. When the AC is in the "negative" phase, that fancy switch connects the winding to the terminals the other way around.
http://electronics.howstuffworks.com/motor1.htm
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
https://en.wikipedia.org/wiki/Universal_motor
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
The commutator is indeed a "fancy switch". Another way of saying the same thing is that the commutator and its bars work as a mechanical rectifier that connects the part of the winding that has the highest induced EMF to the brushes. Since there is a set of positive brushes and a set of negative ones, the resulting voltage across the brushes is a rater smooth DC voltage. There is a slight "commutator tone", but the more bars there are the smoother the voltage.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
What!!, How does it know when it's in the positive cycle or negative cycle and than deliver the current to the correct brushes? Are the rotor bars and or commutator
just set up so they are lined up no matter what position it's started in? Would a 50Hz motor need to be made different than 60Hz. Scratching my head.
Chuck
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
Thank you for the perspective David and Gunnar, enlightened and embarrassed.
Chuck
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
Look at one coil rotating clockwise in a horizontal magnetic field.
As the one coil moves down across the field to the right, from 0 degrees to 180 degrees, a voltage will be induced in the coil.
As the other coil moves up across the field to the left, a similar voltage will be induced in the coil.
These voltages appear in parallel at the brushes.
As the coils continue fro 180 degrees to 360 degrees, a similar voltage but of opposite polarity is induced.
However as the coils pass the zero degree and 180 degree position the brushes transfer to the opposite commutator segments and reverse the coil connections.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
Yep that is a visualization I can rap my head around with additional coils and segments performing the timing and all
part of the "Fancy switch" as described, Two coils would of coarse be very choppy but as Gunnar described with more coils
and segments added the voltage will smooth out.
Thank's Sir!
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: in DC machines, how do commutators convert induced AC voltage into DC ?
It is considered bad form to post once and then never respond or request clarification, or express thanks and appreciation for the assistance of complete strangers who owe you nothing.
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: in DC machines, how do commutators convert induced AC voltage into DC ?