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TMS320F2800156-Q1: foc single-shunt

youjun zhang
Intellectual 610 points

Part Number: TMS320F2800156-Q1

hi expert:

Can you send me the technical document for FOC single-shunt control?

  • 0
    TI__Genius 9020 points

    Hello,

    Here is the for Application Note: Sensorless-FOC for PMSM With Single DC-Link Shunt:

    https://www.ti.com/lit/an/spract7/spract7.pdf

    Best Regards,

    Masoud

  • 0 in reply to Masoud Farhadi
    Intellectual 610 points

    hello expert：

    When a MCU drives two motors with a PWM difference of 1/2PWM period, and both motors adopt a single DC-Link Shunt, may the sampling time of one motor coincide with that of the other motor? How can i resolve this issue?

  • 0 in reply to youjun zhang
    TI__Genius 9020 points

    Yes, this can happen. With single DC-link shunt sensing, current can only be sampled during valid active-vector intervals, so if two motors are driven with a 1/2-PWM-period offset, the sampling windows may overlap. In that case, the ADC triggers for the two motors should be separated by slightly shifting one PWM phase, assigning each motor to different ADC/SOC resources, or using PWM compensation to expand the sampling window. If overlap remains frequent at high modulation, a 2-shunt or 3-shunt method is more robust.

    If both motors need a sample at the same instant and you only have one ADC resource / one trigger path / one ISR slot serving them, then you should treat that as a conflict. In practice, you cannot take two different shunt measurements at the exact same time with one converter path. Even if the MCU has multiple ADCs, each motor’s sample still needs its own trigger and enough analog settling time. 

    Best Regards,

    Masoud