I found many SimpleFOC controller does not have current sensor, so is it a real FOC without current sensor to detect the Id and Iq? Especially the simpleFOC stepper controller.
IMO, no. It is just a stepper motor at that point.
no matter stepper or BLDC controller, is it a real FOC controller without current sensor?
No, the theory of FOC algorithm involves current sensing for current feedback to the controller. Without current sensing, it would be inaccurate to say that the control loop is “real FOC”. It would better be refered to as “Sinusoidal commutation”, where you would take the electrical angualr position sensed by the position sensor as feedback and send PWM signals in a sinusoidal waveform to the BLDC.
So without current sensing, it is NOT FOC, because there is nothing “field-oriented”. In that case, what you are doing is basically applying a smarter way of sending PWM signals compared to say Trapezoidal commutation or 6-step commutation. You still benefit from smoother motion and infinite stator vectors using this method, but you would miss out on torque control.
Thanks for your detail explaination.