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TMS320F2800156-Q1: Inquiry about TI InstaSPIN-FOC Algorithm

Renan Santos Adriano
Mastermind 26275 points

Part Number: TMS320F2800156-Q1

Hello Experts,

We are currently trying to drive an SPMSM motor in sensorless mode using the InstaSPIN-FOC algorithm.

Our system uses a two-shunt current sensing configuration (Phase Current A and C), and the maximum phase current is 50 A.

When we input a Speed Reference value to drive the motor at −40 °C (this condition applies the highest load to the motor, so we perform testing under this condition), the ActRPM reported via CAN communication remains at 0.
However, the motor appears to rotate very slowly.

The ActRPM remains at 0 for about 20 seconds, and then it suddenly jumps to 60 RPM or 80 RPM.
Instead of increasing gradually (e.g., 20 → 40 → 60 RPM), the speed appears abruptly, which seems unusual.

  1. In this situation, which parts of the InstaSPIN-FOC algorithm should we check to resolve this issue?
    (For example, whether parameters such as motor phase resistance should be adjusted.)

  2. What kind of tuning or parameter adjustments are recommended to improve the robustness of InstaSPIN sensorless control under low-temperature and high-load conditions?

  3. Additionally, in our two-shunt configuration, the phase current ADC SOC flag is set when Phase A, B, and C low-side switches turn on (PWM counter = 0).
    Could this method cause the issue described above?
    If so, does TI provide a recommended two-shunt sampling logic for this case?

Regards,

Yunseong Lee

  • 0
    TI__Expert 7835 points

    Hi Yunseong,

    1. Not sure how you are transmitting speed info via CAN interface. Normally the start up process is to run open loop start up first, and then switch to closed loop with FAST observer when motor reach some speed.

    2. For low temp, the biggest risk is change of motor parameter. If you want to improve performance, you may want to calibrate the motor parameter at different temp range and change accordingly for FAST observer, if your motor parameter change largely.

    3. since you only have 2 shunts, then if one of the two phase have very short low side on time, you may face challenge getting phase current feedback. You may need to limit modulation index to make sure the two phases always have sufficient low side switch on time.

    Han