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PFC Design

Sam Ref
Expert 1610 points

Hello,

We are implementing TIDM-2008 (Bidirectional Interleaved CCM Totem Pole Bridgeless PFC Reference Design Using C2000Tm MCU). Questions are;

  • In PFC mode DC Bus Control; the reference .pdf of that design shows (Labs 3 & 4 and Figure 2.9) that we can control current to cope with load changes. That document also shows (Figure 2.11) that the output DC voltage can be controlled/regulated while maintaining low-bandwidth response (~10 Hz). What is the permissible range of that DC voltage change? Can we take that DC voltage to say 5% of the input AC voltage? If not, what is the barrier?
  • Number of switches. We can use only 4 power switches (GaN , MOSFET or SicMOSFET) to realize DC volt control and PFC of single-phase AC input. Correct? In your reference design you use 8 power switches (6 GaN switches and 2 MOSFETs) all to realize interleaving and reduce the ripple. Correct?
  • Three-Phase PFC. Does Texas Instruments have an explicit three-phase PFC reference design that uses 6 power switches? Vienna configuration is not justified in our case.

Regards

Sam Refaat

  • 0
    TI__Genius 11855 points
    • In PFC mode DC Bus Control; the reference .pdf of that design shows (Labs 3 & 4 and Figure 2.9) that we can control current to cope with load changes. That document also shows (Figure 2.11) that the output DC voltage can be controlled/regulated while maintaining low-bandwidth response (~10 Hz). What is the permissible range of that DC voltage change? Can we take that DC voltage to say 5% of the input AC voltage? If not, what is the barrier?

    Figure 3-61 shows this DC voltage change under transient. Voltage Transient With Non-Linear Voltage Loop, Vin 120 Vrms, 880 W to 0 W Transient, Overshoot 16.8 V.

    So this is about 4% of the rated DC bus voltage (400V)

    • Number of switches. We can use only 4 power switches (GaN , MOSFET or SicMOSFET) to realize DC volt control and PFC of single-phase AC input. Correct? 

    The one we implemented is a Totem-Pole PFC with 3 interleaved phases. With 4 switches you can also implement a TP PFC with no interleaving. That will be a single inductor TP PFC design.

    • In your reference design you use 8 power switches (6 GaN switches and 2 MOSFETs) all to realize interleaving and reduce the ripple. Correct? 

    Yes, 6 GaN switches are for 3 interleaved phases. 2 Si MOSFETs switch only at the line frequency (50 or 60Hz)

    We dont have a 6 switch 3phase PFC design at this time. We have TIDA-1606 which implements a 3Ph T-Type multi-level PFC.

    Shamim