• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Answers 3 answers
  • Subscribers 63 subscribers
  • Views 629 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

UCC256301: LLC Resonant converter for variable power supply design

Anup_Shetty
Prodigy 50 points
Part Number: UCC256301
Other Parts Discussed in Thread: UCC256403, UCC256404, UCC28951, UCC28C44, UCC256402, UCC28C40

Can we design a variable power supply with the help of LLC Resonant converter IC UCC256301??

  • 0
    TI__Expert 8210 points

    Anup

    First off for new designs we recommend that you use our latest resonant LLC controller UCC256403.  This device is pin-to-pin compatible with UCC25630x family of devices and has performance improvements.  Details are in the following app note http://www.ti.com/lit/pdf/slua966

    As far as variable power supply, this device can be used in applications where both the input or output voltage varies

    For example with output voltage variation, TIDA-010038 shows this device able to support a constant voltage and constant current regulation, which is typically used for battery charging applications.

    For example with input voltage variation, UCC256404 is specifically designed to support wide input voltage range for startup and operation when PFC stage is disabled in standby mode.  PMP22087 is an example of it configured as such.

    Best Regards,

    Eric

  • 0 in reply to Eric Faraci
    Prodigy 50 points

    Thank you Mr. Eric  for the suggetion

    I referred few high power(500W-800W) LLC converter ref. designs and evaluation module documents available in TI website.One thing i observed is all of them are focused on fixed output voltage/battery charging applications.But i want to design a custamised power supply which has to deliver peak power of 600W with variable output voltage (0V -100V)

    I have few quetions on this project,

    1. Is LLC resonant converter topology best suited  for this application?

    2. If such wide range of output voltage variation setting is not possible should i go for additional buck stage at the output?

    Thank you

    Regards,

    Anup

  • 0 in reply to Anup_Shetty
    TI__Expert 8210 points

    Anup

    Resonant LLC topology is best used for applications that have narrow voltage range.  If the voltage of either the input or output voltage varies, the operating frequency moves away from the optimal operating point.  This PSDS paper has more details on this https://www.ti.com/seclit/ml/slup263/slup263.pdf.  When the voltage range is limited, this performance loss is typically acceptable, but for wide voltage range (such as output voltage from 0V - 100V) the performance of a resonant LLC will generally be unacceptable for most designs.

    One way to resolve this challenge is to add a buck converter on the output, which allows the output voltage of the resonant LLC stage to be fixed at a single voltage.  This will allow the resonant LLC stage to always operate at high efficiency.

    Another way to resolve this challenge is to use a separate topology that can support wide output voltage range better.  For example a phase shift full bridge (PSFB) UCC28951 may be a better alternative than LLC.  PSFB also achieves zero voltage switching so it is a high efficiency topology.

    Best Regards,

    Eric

  • 0 in reply to Eric Faraci
    Prodigy 50 points

    Hello Mr.Eric

    As per cost and complexity of the project is concerned PSFB topology requires additional drivers and 4 HV switches for its operation(cost of IC itslef 10 times more than LLC resonating IC UCC256404!! also requires gate driver ICs).

    I have been part of projects which used Flyback topology(We were able to design a 300W flyback converter using UCC28C44 IC). In the current project im trying to avoid project design errors. Budget is also a main concern !!!!

    LLC topology with buck converter might be a better solution as efficiency is not my primary concern(Around 90% at full load we can achieve i guess).

    Is it possible to digitally implement LLC topology with buck?

    What i think is digital implementation will give more flexibility to design the system as end user preffers because anyways we have to use one controller for the display and meassurement purpose

    Please correct me if im wrong...

    Thank you

    Regards,

    Anup

  • 0 in reply to Anup_Shetty
    TI__Expert 8210 points

    Anup

    You are correct.  A resonant LLC, followed by a DC/DC buck would work in this application.  If you determine that this is the best solution based on design requirements you have, then we encourage you to start your design with this architecture. 

    It is possible to control both power stages with digital controller, but this may be a more expensive solution than an analog LLC with UCC256402 followed by a buck controlled by a device like UCC28C40.  One suggestion that we have is that you can use these analog controllers for the PWM operation of the power stage, and use a lower cost MCU like MSP430 set low speed parameters (such as the reference voltage to determine the output voltage) along with the display and measurement.

    Best Regards,

    Eric

  • 0 in reply to Eric Faraci
    Prodigy 50 points

    Thank you Mr. Eric

    I will start design part of the project.

    I may need assistance in MCU register setting and configuration lerning process.

    Thank you

    Regards,

    Anup

  • 0 in reply to Anup_Shetty
    TI__Expert 8210 points

    Anup

    If you have any questions on the MCU portion please start a new E2E thread.  This will allow the right expert at TI to respond to you faster.

    Best Regards,
    Eric

  • 0 in reply to Eric Faraci
    Prodigy 50 points

    Okay got it,

    Thank you Mr. Eric