Inductor polarity switching question

[Njguy]

Many electric motors use polarity switching as a means of generating torque. I was wondering if inductors resist polarity switching. I read somewhere that inductors resist changes in current. Does this also apply to switching the direction of flow of the current? Thanks guys.

 

[Jaguarjoe]

Changing the 'flow' of the current IS changing the current.

 

[Diver300]

The windings in electric motors have inductance, so they do resist the changes in current. Winding inductance will usually reduce the torque that a motor can produce at higher speeds.

 

[Njguy]

Don't all DC motors with the exception of say stepper motors use polarity switching? All AC motors use it as well?

 

[crutschow]

All motors require a rotating magnetic field to operate. This is generated by the alternating voltage in AC motors, and the commutator or electronic switches in DC motors.

The inductance of the motor is not the primary impedance that determines the motor current, it is the back EMF generated by the rotor rotation. Thus, at startup the motor draws a large current, since its impedance is low due to no rotation, which then drops as the motor picks up speed.

 

[szhighstar]

normally inductor which is only a winding, not polarity requirement, when we are making mass products, we do not take care of polarity, if customer has special requirement, ask to keep same direction, we will add marker toward starting wire.