How does a Brushless Electric Motor work?

Hmm sounds pretty much like a stepper motor to me, what do you think?

No. A brushless motor is designed for low maintenance. No brushes ever need replacement. They are also sparkless so they can be used in combustible or explosive atmospheres (under certain conditions).

A brushless motor is designed to rotate freely when power is applied.

While a stepper motor is a type of brushless DC motor it is designed to rotate a specific number of steps and to hold it's postion when it is not stepping.

Bobmas you stated,

"A brushless motor is designed to rotate freely when power is applied.

While a stepper motor is a type of brushless DC motor it is designed to rotate a specific number of steps and to hold it's position when it is not stepping."

However if you do not keep sequentially energizing the stator coils or a brushless DC motor the rotor will lock in one position in exactly the same manner as a stepper motor. Also a brushless electric motor will stop in defined positions in a not to dissimilar way to a stepper motor when power is removed.

Technically they work on the same principal of having a rotor that is constructed of a multi poled permanent magnet that is rotated by sequentially by applying power to a set of fixed coils. If fact it is fair to say that a stepper motor is a specialized form of brushless DC motor. Then again, since the stepper motors were around first it would be fairer to say that a brushless DC motor is a type of less precise stepper motor.

Fair enough. I never really thought of it that way, since the applications are so dissimilar, but you are essentially correct. Radio Control scale vehicles often apply both types: BDCMs for drive motors, and steppers for steering and control.

I've always liked stepper motors, to me they seem to be an elegant solution to many problems. They have many advantages and can be used in both propulsive and servo or positioning scenarios. Personally I believe they are grossly underused and that's probably because people just don't understand them. Since we are seeing more and more brushless technology and driving circuitry could also drive a stepper maybe we will see more of them in the future.

I use to worked for a computer company and the big line printers we sold used stepper motors to drive the paper feed Whenever a printer was past its useful life I would remove the stepper motors from them before they were dumped. They have proved to be very useful over the years and even though they were second hand and had been thrashed prior to me getting them I have never had one fail. These motors were quiet small (50mm in diameter) but the torque they produced was astounding, if the were being driven there was no way you could either stall them when moving or move them when stationary.

Blah

Wouldst thou care to elaborate on "blah" or is that the extent of your vocabulary?

Goodmorning, Iam reading your stuff, can some one discribe in detail a stepper moder

JR

G'day JR,

The description in the link from post #9 is not the best description I have seen for stepper motors. If you are still confused after reading it post a further query on this thread and I will post a simpler and easier to follow description.