in order to understand bldc motors and their working principle, I read a lot on the web, and I see them like a tripolar steppers, am I right?
Steppers are intended to work in a open loop without feedback. The current trough windings is preset to a constant value at the driver (chopper) and the rotor is hold at certain position...all the theory you have already seen on the web.
If we closer look at the holding position of stepper motor, we can notice that torque is zero, because the rotor field and stator field are alligned.  A max torque is produced when you want to move the rotor from its holding position, looking electricaly this is 90 degress difference between rotor field and startor field - you can use two magnets to proove that, the force is maximal when magnets are placed 90 degress from each to other.
With BLDC and PMSM you have a feedback, as you depicted a hall sensor for proper commutation. If you look carefuly the stator is always commutated in such way that stator field is 90 deg with respect to the rotor field. In this case the rotor would give max torque always, therefore you also need a current regulator.

In few words: The current trough BLDC is always proportional to the output torque of the motor, at standstill with no static load, the current is zero. The stator field in the BLDC is always oriented to be 90 deg shifted with respect to rotor filed.