I'm trying to control 12V 12,000 rpm BLDC motor with 3x120° Hall sensors using ST evaluation board based on L6229 IC.
I tried to control motor's speed by feeding PWM to FWD/REV pin as suggested in the design note.
When PWM = 0 motor spins in one direction at full speed, 255 - opposite direction full speed. Coming closer to PWM 128 - speed proportionally reduces till zero as expected, but TORQUE ALSO DROPS DRASTICALLY...
Also tried to feed different control voltages to Vref pin, but can't notice any differences in motor behavior.
I need constantly slow-down/speed-up motor's speed and keep acceptable torque on slow speeds (motor most of the time will work on 1/3 of top speed).
And BLDC motor in theory have bigger torque on slower rpms. But I can't achieve it. Maybe someone can help me wit this or recommend easy/cheap driver better suitable for this task?
And there is eval board schematics: :
And also attaching motor curves: