On Fri, 2012-04-13 at 14:01 -0500, Gabriel Willen wrote: > I understand the formula for power, and i realize its all that matters. > Watts are watts no matter what the volts or amps are. I also know that a > bldc motor and asynchronous motor are very similar. That's why I'm curious > how the cogging In a bldc motor don't affect it being a servo. If I could > buy a 660w bldc motor that runs at 48v dc to a driver and ac to dc supply, > or 310v version with an amplifier that excepts 110v ac. Is there a benefit > to higher voltage? > > Gabe
Yes, voltage limits speed. If you spin a BLDC motor shaft, it becomes a generator. If at say, 1000 RPM you get a voltage of 30 Volts out, in order to run the motor as a motor at 1000 RPM, you will need to supply 30 Volts into the motor. The faster you want to go, the higher the generator/motor voltage will be. If you put a load on the motor, the current will go up, but the voltage needed to keep the RPM the same will be close to the same as with no load. I think also for a given motor size, higher voltage is more efficient, because there is less current for the same power. Current creates heat, so I believe a higher voltage motor will run cooler, or be able to handle more power. As for cogging, this only comes into play when a motor is driven by a constant voltage or current supply. The shaft speed or torque will vary slightly as the poles pass each other. Some motors are designed to minimize this by twisting the rotor poles or by adjusting the pole geometry in others ways. For CNC, the motion control system compensates for the cogging, so this rarely becomes an issue. Although stepper motors need strong cogging in order to define step locations. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
