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TPSF12C1QEVM: TPSF12C1QEVM and TPSF12C3QEVM active filters

Mohammad Ali
Prodigy 10 points
Part Number: TPSF12C1QEVM
Other Parts Discussed in Thread: TPSF12C3QEVM,

Dear All,

I hope this message finds you well. I am writing to update you on our recent efforts involving the TPSF12C1QEVM and TPSF12C3QEVM active filters that we purchased to integrate with our single and three-phase passive filters. We have built various configuartions of the passive filter with a active filter such as 1-satge and 2-stage EMI filter with LC topology.

We successfully measured the attenuation of the combined filter (Active + Passive filter) using a vector network analyzer. In the common mode (CM) configuration, the active filter demonstrated excellent performance, providing an attenuation of about 20-28 dB in the frequency range from 100 kHz to 2 MHz.

However, when we conducted EMI measurements using the following setups:

    LISN + Input filter (Active + Passive) + Inverter + 25m motor cable + Motor
    LISN + Input filter (Active + Passive) + Switched mode power supply + Resistive load

We encountered challenges. Despite our best efforts, the active filter did not function as expected. We performed measurements both with and without the active filter, and the results were almost identical.

Considering this situation, I would greatly appreciate any suggestions or guidance you might have regarding our EMI measurement setup. Your expertise would be invaluable in helping us address these issues effectively.

Thank you for your time and assistance. I look forward to your valuable insights.

Best regards

Mohammad Ali

  • 0
    TI__Guru 67712 points

    Hi Mohammad,

    Please send completed quickstart calculator for this design. You will need to have the impedance of the CM chokes. Note that two chokes are required, and the AEF senses and injects in between the chokes. Also, note the design flow provided in the EVM user's guide.

    One common issue due to high incident CM noise is that the INJ pin voltage saturates, so you should monitor this voltage with a scope. If this is actually an issue, then we can recommend an alternative damping network with lower impedance (higher caps, lower resistances).

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    Prodigy 10 points

    Hi Tim,

    Thank you very much for your reply!

    I wanted to update you on my recent investigations regarding the EMI filter configurations, specifically focusing on the 1-stage LC-topology and the 2-stage LC-topology (LCL).

    Upon conducting tests, the 1-stage LC-topology demonstrated effective performance within the system. However, the 2-stage LC-topology did not yield the expected results, failing to function properly. Here are the details for both configurations:

    1-stage LC-topology:

        2Cx = 3.3 uF
        CM choke L = 2.8 mH (ferrite core with 15 turns)
        2Cy = 4.7 nF
        Active filter components: 2Csense = 680 pF, 1Cinj = 4.7 nF
        EMI reduction: 10-22 dB in the frequency range from 300 kHz to 3 MHz

    2-stage LC-topology (LCL):

        2Cx = 3.3 uF
        CM choke L1 = 2.8 mH (ferrite core with 15 turns)
        CM choke L2 = 322 uH (ferrite core with 5 turns)
        2Cy = 4.7 nF
        Active filter components: 2Csense = 680 pF, 1Cinj = 4.7 nF
        EMI reduction: 3-4 dB in the frequency range from 300 kHz to 650 kHz

    The EMC measurement setup involved LISN, input filter (active + passive), switched-mode power supply (switching frequency of 100 kHz), and a resistive load.

    Given the unsatisfactory performance of the LCL filter, I am seeking your expertise for suggestions on an alternative damping network with lower impedance. Your insights are invaluable, and any guidance you can provide would be greatly appreciated.

    Thank you for your time and assistance. I look forward to your feedback.

    Best regards,

    Mohammad

  • 0 in reply to Mohammad Ali
    TI__Guru 67712 points

    Hi Mohammad,

    This AEF is only setup to function with two chokes. It's really a CLCL filter (going from CM noise source to power input), where C designates Y caps and L represents the CM chokes.

    3808.TPSF12C3 quickstart calculator A5.xlsm

    Send on the completed quickstart file if possible (latest version attached here), as this allows us to check stability. Also check the INJ pin voltage swing as mentioned previously to ensure linear operation of the amplifier.

    Is the AEF applied on an AC or DC input here?

    You can also refer to the FAE and collateral here: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1257197/faq-tpsf12c1-and-tpsf12c3-power-supply-filter-ic-faqs

    Regards,

    Tim