instaspin-FOC questions

Perhaps I wasn't clear.  I understand how to debug in eclipse and have used it for many other projects.  My problem is that all these buttons (resume, step over, step into, etc) are all greyed out.  Do I need to dig into some menu or fiddle with the switches on the board?

For real-time variable update in the watch window, make sure that this button is pressed . 

The lower top end of the motor is due in part to FOC and space vector generator (SVGEN) but it has a solution.  Inherent with FOC is the control of a motor using sine-waves.  To create a true sine-wave, the full voltage of the DC buss cannot be utilized.  With a trapezoidal motor control, the DC buss is fully switched across the phases of the motor for a whole commutation cycle thus fully utilizing the DC buss voltage, by doing this it is also more noisy at all speeds.  There is a technique called over-modulation that can be used with FOC and the SVGEN which allows the output waveforms to become trapezoidal when more voltage is needed to attain those higher speeds.  Over-modulation can be difficult to implement depending on the type of current feedback that your inverter is using.  It is most difficult when utilizing shunt resistors and very easy when using inline current sensors like LEMs or Hall sensors.

I am assuming that you are using a BLDC motor controller designed to run model airplanes or cars.  One thing to look for is if the controller mentions that there is a phase advance programmed into the trapezoidal control.  The phase advance is similar to field weakening and will cause the motor to run faster than your DC buss would normally allow.  Field weakening with FOC will also allow the motor to spin at speeds higher than the DC buss allows and should allow you to attain speeds that you require.  Something to think about is that field weakening is controlled by increasing the magnitude of -Id current.  The spatial vector for Id current is in parallel with the field vector of the motor and creates no torque.  So by increasing -Id current, more power is lost in the motor and produces no more torque i.e. the motor will be less efficient.  I am kind of long winded here but what I am trying to say is that it is best to get the speed that you need with over-modulation first to keep high efficiency and then use field weakening if more speed is needed.

The most acceleration possible is acquired when Iq is at the max value for the motor.  The speed PI controller is a filter which slows down this step command of Iq.  One thing that you could do is use a feed-forward option in the speed PI control.  That way your reference speed command will directly affect the Iq reference command.  To see the motor's true performance, I would remove the speed PI control and directly command Iq.  You can command a step in Iq that goes from 0 to max Iq and see if you get the acceleration performance that you require.  You could even provide a much higher Iq value than the motor is specd at, as long as it is not greater than what the inverter will allow, to have even more acceleration performance.

-Eric

Thanks everyone for the great responses.  I have been on vacation for the past week, and will hopefully get back to this testing in the next day or two.