Part Number:DRV8301-HC-C2-KIT
I'm interested in understanding what's happening in each of the InstaSpin BLDC blocks.
The compiled library is located here in control suite
"\ti\controlSUITE\libs\app_libs\motor_control\libs\InstaSPIN-BLDC\v100\lib\C28x_InstaSPIN_BLDC_Lib.lib"
Is the source code available to look at? Do I need to sign an NDA or something?
The reason I need to look is because we need to decouple the PWM and ISR frequency. We're violating a DRV chip parameter by over using the charge pump regulator GVDD to drive the MOSFET gate capacitors at 35kHz. Equation is I = freq x 6 x GateCap and only 30mA is available. We're using around 45mA and already damaged some chips.
20khz is the max to run PWM without damaging the DRV chip. The problem is that limits your RPM to ~10k RPM and we need around 12k RPM.
Now the next issue is we've decoupled the ISR and PWM but now you have a ISR running at 40khz and a PWM at 20khz. You need to only sample BEMF at the PWM OFF times within each of the 6 steps. At twice the frequency you get 1 sample at the OFF time and 1 sample at the ON time. This messes up the BEMF integration waveform and thus the commutation timing.
Is there a way to convert the ON time reading to an equivalent OFF time reading?
On time is essentially 1/2 PVDD at the neutral point.
OFF time is essentially 1/2 Motor voltage at the neutral point. So if you're 50% duty cycle it's 1/4 PVDD.
Any help on the libraries or solving this issue would be greatly appreciated.
My setup is
Setup:
DRV8301-HC-C2 kit Rev D
CC2803x ISO DIMM Rev 1.3 control card
CCS 6.2 and latest control suite install.
PWM: 35kHz
ISR: 35kHz
Motor:
KDE600XF-530-G3
Poles = 10, verified by counting magnets
Voltage = 22V - 52V
Current = 88A continuous, 170A peak
Kv = 530 RPM/V
L = 15uH - measured by LCR
R = 17mOhm
14 x 7 prop on static thrust stand