Hey Swede, it seems our thoughts tends to cross.
I have Ebought a BLDC servo that I want to use on my lathe project. BTW: Do you know that the new KaVo HF spindles are actually BLDC synchronous motor technology?
Some servo drives come as speed controllers rather than position controllers. These are the ones you would look for. Often that is what you can Ebuy, as they often come from conveyor applications that are speed controlled. The difference can often be found by just one digit or letter in the order number of the drive. The real difference lies in the firmware inside the drive. I guess a huge number of buyers that did not bother to check first gets quite disappointed if they want to use it as a position drive.
What you look for in a motor is high RPM capability and low Kv. Power is the product of torque and speed. Usually torque is fairly constant up to max RPM. So you want to exploit this by driving it to max speed. The voltage needed is largely proportional to speed. So as to not get limited by the max voltage you have available, look for a low Kv.
For a high energy density a BLDC motor is to be preferred over a DC. The DC motor have it's windings deeply embedded on the rotor, so cannot easily get rid of heat. The BLDC have only magnets on the rotor, so the only heat generated there are a very low eddy current heating. This is where the BLDC beats the Asynchronous motor that have more current generated in the rotor cage, it's a necessity, as this kind of motor is actually a transformer with one rotating winding set. In the BLDC the windings are in the stator, so it can much more easily be dissipated to the surrounding air. If you add forced cooling you can increase the continous rating by as much as 2, while the max rating will stay the same, usually 4 times the uncooled continous rating. With DC or asynchronous motors the heating in the rotor cannot easily get out to be dissipated.  |