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Inverting power supply issue

Cherry Zhou
Mastermind 22235 points

Other Parts Discussed in Thread: POWERSUITE, TIDM-HV-1PH-DCAC, SFRA

Hi team,

Here's an issue from the customer may need your help:

Referenced to the DC-AC unit section under POWERSUITE Single Phase Inverter: Voltage Source TIDM-HV-1PH-DCAC project for an inverting power supply, and the customer has the following 4 questions:

1) The file voltagesourceinvlcfltr_settings.h in source code voltageSourceInverterLCFltr_F28004x has the following statements:

// BUILD 1 Open Loop Check the Inverter
// BUILD 2 Closed Current Loop Inverter forced sine angle
// BUILD 3 Voltage loop with inner current loop

Is it possible to provide the corresponding load voltage and current waveforms for three cases with non-linear loads (frequency converters, switching power supplies, etc.)?

2) When BUILD is 2 or 3, is there any reference documents? 

3) Is the Voltage loop controlled by a transient or average value? Or other way of controlling it?

4) Inner current is related to what? Is the current of the current inner loop taken from the inductor current, the capacitor current, or the load current?

Could you help check this case? Thanks.

Best Regards,

Cherry

  • 0
    TI__Expert 4200 points

    Hi Cherry,

    1) Figure 34 is the only waveform that we have. The design was released a long time ago and we currently don't have a working test setup.

    2) The details are provided in the user's guide. What do you specifically looking for?

    3) The voltage loop regulates the sampled value of Vbus (average)

    4) The inner current loop regulated the sampled value of the inductor current (average)

    Best,

    John

  • 0 in reply to John_K
    TI__Mastermind 22235 points

    Hi John,

    Thanks for your help.

    John_K said:
    2) The details are provided in the user's guide. What do you specifically looking for?

    / BUILD 2 Closed Current Loop Inverter forced sine angle
    // BUILD 3 Voltage loop with inner current loop

    The customer is looking for the reference documentations of  above 2 cases, and there are many sections in the manual that do not use SFRA. How do the inverting waveforms control when SFRA and DCL are not used?

    John_K said:
    3) The voltage loop regulates the sampled value of Vbus (average)

    Voltage loop should be a voltage waveform of the inverting output combined with Vbus, not just Vbus, is that right?

    John_K said:
    4) The inner current loop regulated the sampled value of the inductor current (average)

    Is inner current inductor current, capacitor current, or load current? Is the harmonic current taken into account when averaging?

    Thanks and regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Expert 4200 points

    2) The compensator designs are shown in p.32 (Build2) and p.35 (Build3) which are based on SFRA. p.27 and p33 show the block diagram of the control loop which includes DCL

    3) Sorry, it was my mistake. The voltage loop tries to regulate the average value of Vac.

    4) Check p.27. The inner current loop senses the inductor current. The key for harmonic suppression is PR compensator shown in p.35. It boosts gain at 5th, 7th, and higher-order harmonics to suppress them.

    Best,

    John

  • 0 in reply to John_K
    TI__Mastermind 22235 points

    Hi John,

    1) What does the inner current current loop do? Is the current reference value of the current loop sinusoidal or fixed when BUILD is 3? Is the current data captured by the current loop sinusoidal waveform current data or is the current data of other harmonics superimposed on the sinusoidal?

    2) Is the inductor current consistent with the bottom waveform below? If so, is that the reference value of the current inner loop sinusoidal or other waveform data?

    3) Could you help double check if the voltage loop is the average value of Vac, since the customer think it's the transient value as the codes show.

    4) And the customer is wondering if it's possible to provide below info:

    • The current waveform of the H-bridge output
    • The voltage waveform across the inductor
    • The current waveform of the inductor
    • Current waveform diagram of capacitor inductance with rectifier load

    Thanks and regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Expert 4200 points

    HI Cherry,

    1) Inner current loop regulates the inductor current to follow the sinusoidal reference. The current reference is generated by the outer voltage loop. This is described in P.12. What does current data mean?

    2) Can you elaborate on which bottom waveform you are referring to?

    3)The average means the average value of 1 switching cycle. It does not mean the average of the entire line cycle.

    4) Sorry, we currently don't have any working hardware.

    Best,

    John

  • 0 in reply to John_K
    TI__Mastermind 22235 points

    Hi John,

    John_K said:
    2) Can you elaborate on which bottom waveform you are referring to?

    Sorry I forget to post the waveform, what I'm referring to is the below waveform:

    Thanks and regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Expert 4200 points

    The bottom waveform seems like the voltage across the inductor. The inner current loop regulates IL1 to be sinusoidal.

  • 0 in reply to John_K
    TI__Mastermind 22235 points

    Hi John,

    Does the load peak of our inverter with switching power supply (or with similar switching power supply) clip?

    Thanks and regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Expert 4200 points

    Hi Cherry,

    Can you elaborate on your question? are you asking if the inverter has protection when it hits maximum power?

  • 0 in reply to John_K
    TI__Mastermind 22235 points

    Hi John,

    Flat top occurs with a nonlinear load on customer side, so they're wondering how about our device? 

    Thanks and regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Expert 4200 points

    Cherry,

    Please create another thread for a different topic and please provide what flat top you are referring to.

    Best,

    John