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TMS320F2800157: Not able to achieve maximum speed under minimum load condition (FWC)

Kirana H P
Prodigy 235 points

Part Number: TMS320F2800157

Tool/software:

Hi team,

We are working on custom board, and we can be able to run motor in both speed and current mode (torque control mode). For this application we are using mid-drive IPSM motor and even we can be able to achieve peak torque.

I enabled field weakening method and we can be able to achieve maximum speed of 6000 RPM but when I am testing in dyno where we coupled two motors back-to-back, it is running only up to 3300 RPM. Above that even if we inject more negative Id current also not working.

Because of this issue if I run opposite motor with 3500 RPM (speed mode) and if I apply load from my side (torque mode) phase currents are oscillating but speed is not oscillating.

Why motor is not running above 3300 RPM under load condition, when it is running in 6000 RPM in bench (no-load).

I am expecting response from TI experts, please suggest the way to resolve this issue.

Thank you.

Regards,

Kirana H P

  • 0
    TI__Expert 7835 points

    The FWC will apply negative Id, which will reduce the magnetic field density of the rotor. This will reduce BackEMF constant, which allows the motor to run at higher speed, with the cost of reduced torque output. As a result, you can run to full speed with no load and will limit the speed when you apply load with dyno. Thanks.

    Han