I have just built an electric skateboard based on a Hobbyking 50A ESC, controlling a 400Kv outrunner-type brushless motor. The skateboard requires a little nudge at the beginning to run regardless of the speed setpoint, otherwise it struggles and vibrates. This is not an issue of torque capability, as it can carry me up a slope without issue once it has non-zero speed.
I'm starting to think, in spite of discussions I find on the web saying these sorts of controllers use sensorless position feedback algorithms, that the stator rotating field is set to rotate at a given speed (i.e. fixed frequency) regardless of the rotor position - resulting in very little torque when driving very high load inertia at zero speed. I was expecting some kind of closed loop control of the stator field with respect to the rotor field (90°), wouldn't you?