I'm trying to get the torque constant of a bldc. Based on this: how to read datasheet I just divide the torque at any given point with the current. I tried out that method with different values and I get different constants. What do I do wrong? How can I calculate the constant if this method is wrong? datasheet
It looks like that data sheet is for the current drawn from the 48V supply. The torque constant of a motor applies to the ratio between the shaft torque and the current applied to the motor itself. It's fairly close to the motor torque over a wide range of shaft speeds (in both directions -- torque vs. current is close to the same when the motor's acting like a generator as when it's acting like a motor).
The current drawn by the motor driver of a BLDC is different, because the driver (if it's decent) is a switched amplifier, so the current drawn is just the total power (motor shaft power plus any losses) divided by the supply voltage.