New Motor Technology

There's nothing to prevent a brushless DC motor from running in all four operating quadrants (motoring or generating/braking, in forward or reverse). Any limitation is imposed by the controller hardware and/or software that you're using. Here's a listing of brushless dc motor suppliers from GlobalSpec. Many supply 2 and 4 quadrant drives (2 quadrant is forward/reverse, 4 quadrant refers to fwd/rev and motoring/generating).

Good luck.

"I am interested in a brushless dc motor which is reversible, and I was told by my supplier that the technology does not exist. Is he correct or is he trying not to lose my buisiness?"

Try InMotion Technologies (IMT) for special highly efficient axial flux motors, used in Solar Cars and electrically assisted pushbikes. http://www.imtmotors.com Cheers, Ganter

For simple tasks, I have great success with www.allmotion.com

Service is geat too.

I worked on these motors for many years and never seen a reversible one. may be there is something in market.

but even if it is not available I believe that this can be made with some tradeoff with cost and performance.

I mean cost will increase and performance may degrade little bit.

Brushless servo drives and motors are basically DC by the time that the PWM voltage hits the windings. They are fully reversable, controllable and you can control accel ramp, decel ramp and speed as well as a lot of different programmable variables. Try Danahermotion.com

They exist, you just have to choose the prefered method of switching

Magnetic Reed switch

Light and photodiode switches

Hall effect devices (this is the prefered method)

If anyone knows of any other method, I would love to hear about it.

Some control electronics use a sensorless approach.

I beleive they rely on back emf.

Some other feedback methods/ devices include resolvers and encoders, in addition to those that you mentioned, and they are very position-accurate.

I think the question is about feedback for phase switching, i.e. determining the rotor's magnetic pole position.

I would not use an encoder/resolver for that purpose.

Hall effect sensors at the switching points are probably the most common commutation sensors used for brushless dc motors. Encoders/resolvers can also be used although they're more expensive.

ALL Brushless motors ARE reversible. To use brushless motors, you need an Electonic Speed Controllers ( ESC) these have 2 wires comming in ( DC input + and - ) and 3 leads out to the brushless motor. reversing any 2 of these 3 leads changes direction of rotation of the motor. You can hook 2 of the wires up to a DPDT switch to do remote reversing using a servo. HLG