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TIDM-02008: Question of Totem Pole PFC Loop Control

Green Deng
Expert 4490 points
Part Number: TIDM-02008

Dear team:

My customer asks:

1, TIDM-02008 consists of totem pole PFC, current loop control, duty 3 parts, which part is more important?

2, The voltage loop output is limited to 0.7, why?

Best regards

Green

  • 0
    TI__Expert 4200 points

    Hi Green,

    Q1. I don't understand what you are asking. what do you mean by more important? 

    Q2. Voltage loop output is the current reference. The maximum current sensing value is at around 25 A and the rated current is at around 15 A. The per unit value of 0.7 corresponds to 17.5A. If you don't limit the voltage loop output, it will generate a high current reference during start-up or load transient.

    Best,

    John

  • 0 in reply to John_K
    TI__Expert 4490 points

    Hi John:

    "More important" means in the process of dynamic regulation, which of the above three plays a greater role?

    Do we have relevant theoretical documents about this control method?

    In addition, what is the reason why the current loop is limited to -1~1?

  • 0 in reply to Green Deng
    TI__Expert 4200 points

    Hi Green,

    I still don't understand the question. How can you define TIDM-02008 as 3 parts? and why do you want to figure out what is the most important part?

    All the control variables are in p.u value. if current reference is higher than the ADC sensing range (I_ref > |1|), it will lose controllability.

    Best,

    John

  • 0 in reply to John_K
    TI__Expert 4490 points

    Hi John:

    Regarding the role of duty, the customer wants to confirm whether the role of the current loop output gi_out is small, and the duty change caused by the input voltage/bulk voltage is large during the loop adjustment process?

    Best regards,

    Green

  • +1 in reply to Green Deng
    TI__Expert 4200 points

    Hi Green,

    Let me clarify your question. Does the customer want to see the impact of the feedback term (gi_out ) and the feed-forward term (Vin/Vout)?

    They are both important. The feedback term actually regulates the output and the feed-forward term helps reduce the control effort in feedback control. without feedforward term, feedback control struggles with dynamics such as start-up.

    The feed-forward term has a larger magnitude but what actually regulates output is the feedback term.

    Best,

    John