Other Parts Discussed in Thread: TINA-TI
Hi Clark,
Thank you very much for designing TIDA-00901. It is a great design.
I have a question on RC filter for sensing phase voltage and phase current. In your design, RC low-pass filter for phase current (ISES_A, ISES_B, ISES_C) is R=56 ohms and C=2200 pF. I believe it is a nice selection for the MCU. However, the filter for phase voltage and PVDD (VSEN_A, VSEN_B, VSEN_C, and VSEN_PVDD) uses C=0.1 uF. The voltage divide resistors 25.8K and 4.99K lead to the parallel resistance of 4.18K. The time constant of R=4.18K and C=0.1 uF is significant slower than that for phase current. I believe phase voltage is used to measure BEMF, which trace the position of the motor, which is required for FOC control. Do you think such slow RC time constant is enough for tracking the motor position in FOC control? Will it be better to use the same R and C in phase current and phase voltage?
Thanks and I look forward to hearing from you,
John