Locomotive motors

[Anonymous]

I was wondering whether the motors in HO locomotives are the brushed type with brushes and a commutor or the brushless type.

[jwr_1986]

It depends on the manufacturer . Usually lower priced units will have open frame motors with brushes and commutator. Higher priced units have the more effeicient can motors which to my understanding are brushless. Hope this helped and please forgive my spelling.

Jesse

[Virginian]

I have not, and do not expect to see a brushless DC motor in an HO model. This goes for can motors as well as open. If anyone knows of a source for brushless DC motors please share it (TIC). I'd be real interested to see how they work.

[Anonymous]

A quick motor primer:

Normal motors work by moving wire (coiled around a ferrous metal former) inside a magnetic field, generated by either a single magnet with field pieces (open frame motor) or opposing magnets (can motor). Power to the coils is delivered via brushes and commutated to maintain motor motion. Torque is easy to make with these motors, and they've found a place in our hobby that's well suited for them.

Coreless motors dispense with the ferrous bobbin, and use only the windings themselves for structure, and put the magnet in the middle instead of outside the windings as in a can motor. These are great for high RPM use, but are pitifuly weak when it comes to torque, compared to normal motors. We don't see many of these outside pagers and cellphones with a vibrate feature.

"brushless" motors are actually AC induction motors, just like those used in the latest generation of diesels. They require a 3-phase (or more) controller and many require sensors for positional feedback. The system is complex, and would require a total overhaul of every motor control system as modellers know it to implement on a wide scale. I doubt we'll see it in any model any time soon.

Please excuse typos and grammar. It's 1am.

-dave

[nfmisso]

QUOTE: Originally posted by Virginian

I have not, and do not expect to see a brushless DC motor in an HO model. This goes for can motors as well as open. If anyone knows of a source for brushless DC motors please share it (TIC). I'd be real interested to see how they work.

VGN:

Here is a source for small brushless motors:
http://www.micromo.com/Products/productdisplay.asp?CPTID=29

The physics behind a brushless DC motor is the same as a bru***ype. Just the details are different. Brushless DC motors are typically three phase, and the pernament magnet rotates (rotor). It is divided into an even number of poles (2,4,6,8,....), alternating north and south. The stator is typically stamped laminations with alternating slots and teeth. Typically, the number of slots is divisible by three (3,6,9,12,15,....). There is motor driver chip that either gets rotor to stator position information from sensors or measuring the bemf while the motor is spinning or the inductance of each winding when the rotor is stationary. And power drivers (usually six transistors) which connect the three leads from the motor to + or - and regulate the current or voltage going to the motor.

Every 5¼" and smaller hard drives' spindle is powered by a brushless DC motor.

[Virginian]

Thanks Nigel, live and learn. Next question, what's three phase DC? Pulsed, or what?