• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 1212 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UCC28180: 400Hz For Aerospace?

Joshua Gerdes
Prodigy 100 points
Part Number: UCC28180
Other Parts Discussed in Thread: UC3854A, UCC28064A, UCC38050

I am in need of a PFC for a low power system ~40W maximum. While I do not require high power factor I do require low THD, >10%. My plan has been to use a CCM boost PFC which - the boost stage also doubles as energy storage for power interruption. Trouble is I don't see a lot of controllers advertised to work at 400Hz line frequency. The UC3854A/B products are supposedly 400Hz capable as its discussed in the datasheet, "The bandwidth of the current amplifier has been improved as well to 5 MHz typical. While this is not generally an issue at 50 Hz or 60 Hz inputs, it is essential for 400 Hz input avionics applications." I imagine I can use this part, but I like the light-weight simplicity of the UCC28180. Can it operate at a 400Hz line frequency? I know the part doesn't sense the line voltage, so I'm not really sure what to think here. 

Do you have other recommendations? I imagine you'll probably recommend transition mode but I worry for the impact to emissions and my differential filter.

Thanks!

  • 0
    TI__Mastermind 27095 points

    Hi Joshua,

    Yes, UCC28180 can support 400Hz AC line frequency. This E2E post has some data from our EVM with 400Hz line frequency:https://e2e.ti.com/support/power-management/f/196/t/826755?UCC28180-ucc28180

    While 40W fits much closer with transition mode, there is nothing preventing you from doing CCM PFC here with UCC28180.

    Best Regards,

    Ben Lough

  • 0 in reply to Benjamin Lough
    Prodigy 100 points

    Okay, that's a start! I see a screen shot of the input current at 400Hz and that is helpful, although I don't know whether or not I'll be able to hit 10% THD at 400Hz. I'm planning on doing some prototyping of the design but I want to give my self the best chance at success with the first prototype. So a few follow-up questions:

    1) The 28180 does not sense the line voltage, and I have read the description of how sinusoidal current is generated: "The ramp-ICOMP intersection determines tOFF, and hence DOFF. Since DOFF = VIN/VOUT by the boost-topology equation... the average input current is also sinusoidal in wave-shape." I can't say I fully understand this, but I have read that a typical PFC requires the bandwidth of the current mode error amplifier to be high to operate at 400Hz line freq. This is mentioned in the UC3854A/B datasheet. So my question is does this architecture still necessitate a high bandwidth current error amplifier and if so, what is the bandwidth of the one in the 28180?

    2) I see a PSpice model is available for the 28180. Does it accurately model the architecture of the control loop? I'd like to use the Spice model to evaluate the performance before making a prototype.

    3) As for transition mode controllers, what would you recommend for 400Hz 40W design?

  • 0 in reply to Joshua Gerdes
    TI__Mastermind 27095 points

    Hi Joshua,

    The current control loop is externally compensated with a capacitor so there is some ability to adjust the bandwidth externally. I would suggest taking a look at the UCC28180 calculator which can calculate the current loop bandwidth for you. 

    The Pspice transient model should be representative of the control behavior of UCC28180 but I am not sure how accurate a simulated PF/THD result would be to real life.

    For avionics, we recently released a reference design with UCC28064A that meets DO-160:https://www.ti.com/tool/PMP30763. This might be overkill for 40W however. The multiplier in UCC38050 can handle 400Hz just fine if single phase TM PFC is preferred but we don't have a reference design showing this unfortunately. I think if THD is most important here, CCM is better than TM in this regard.

    Best Regards,

    Ben Lough