Hi,
I want to make a speed controller for 48v 250w bl-dc motor , ı searched on the internet for information but there isn't much thing to go on. Can anyone tell me at least where i should start from?

 

There are several versions of BLDC motors, some with external commutation, some not, you need to specify the type.
Max.

 

There are several versions of BLDC motors, some with external commutation, some not, you need to specify the type.
Max.

ı didn't understand completely but shortly the motor has got 3 hall sensors and 3 phases

 

There is a development Board and software put out by Picmicro on BLDC motor controller, you can download the S/W and the schematic of the board as an example.
It is the PICDEM MC LV board DM183021.
Max.