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When will the three-phase four-wire system be used in the charging pile circuit?

Part Number: UCC27524

I was recently following up with a customer of a charging pile and learned that their system block diagram uses a three-phase three-wire system. I found in some material from ti that the system block diagram uses a three-phase four-wire system.


I have the following questions.


1、How do these two methods affect the charging pile system?
2、 is there any difference in application between the two wiring methods?
3、What is the difference between the control method of the fourth group of bridge arms and the control method of the other three groups of bridge arms?


I hope you can help me with the above questions. Thank you!

  • Hi, Hailan,

    I have asked our SEM team to comment on this since you are asking about architectural trade-offs at the system level.

    Best regards,

    Don

  • Hi Hailan,

    below you find my answers in bold:

    1、How do these two methods affect the charging pile system?

    • By having a neutral connection in your system, you can control unbalanced current. This can be useful during V2G and V2H applications, where your would like to provide power from the battery only to single-phase and dual-phase equipments in your network.
    • Another important feature to mention when you have the neutral connection is that you can apply a de-rating charging strategy in your grid. For example, in your household you are capable to provide 16 A per each phase (three-phase grid,11 kW). If one phase is loaded by other equipment, you can continue to charge your car by only limiting the current in one phase.


    2、 is there any difference in application between the two wiring methods?

    Without neutral connection:

    • space vector can be applied, thus allowing an higher exploitation of the converter
    • caps size can be reduced because there is not power ripple in three-phase system

    With neutral connection:

    • if neutral connected to middle point of caps, space vector cannot be applied.
    • If neutral connected to half-bridge, space vector can be applied.
    • DC caps must handle power ripple
    • neutral connection is not always present.

    Bigger caps for the power ripple
    3、What is the difference between the control method of the fourth group of bridge arms and the control method of the other three groups of bridge arms?

    I suggest you to give a look to the following papers, here you find info about control method difference between the two topologies:

    Thanks and Best Regards

    Riccardo