Selecting a operating frequency for DC DC converter

Discussion in 'Power Electronics' started by Mahantesh Teli, Jul 19, 2017.

  1. Mahantesh Teli

    Thread Starter New Member

    Apr 2, 2016
    21
    0
    Hi,
    1, How to select the operating frequency for any DC DC converter.?
    2, What All parameters need to look at while selecting operating frequency ?
    3, What is the impact on selecting the wrong operating frequency ?

    Rgds,
    Mahantesh
     
  2. wayneh

    Expert

    Sep 9, 2010
    16,102
    6,217
    I can’t give you a complete answer but I can tell you that it’s a compromise. This is what engineering is about, finding a design that balances competing factors.

    A higher frequency allows using smaller components for storing energy, inductors in this case. But the design challenge becomes increasingly more difficult with frequency. 10kHz might be easy while 10MHz is very difficult.

    The design process is iterative. Pick a set of specifications you want to meet, select a topology, start simulating and choosing components, find out how high you can go with real components.

    While you’re doing all this, keep in mind that it’s all been done already by experts and can be purchased for next to nothing on EBay.
     
    Mahantesh Teli likes this.
  3. ian field

    AAC Fanatic!

    Oct 27, 2012
    6,543
    1,197
    Wayneh is right - there's usually a lot of compromises in SMPSU design. pushing up the frequency lets you get away with smaller cheaper reactive components. But you soon start hitting bottlenecks - BJT B/E storage time, MOSFET gate capacitance charge/discharge power, Trr in rectifiers and eddy losses in core ferrites to name a few.

    Run of the mill commercial units are often around 20 - 50kHz. Searching on various controller chips will turn up application notes for designs that run somewhere around 2MHz or so.
     
    Mahantesh Teli likes this.
  4. Mahantesh Teli

    Thread Starter New Member

    Apr 2, 2016
    21
    0
    Thank you Ian
     
  5. Mahantesh Teli

    Thread Starter New Member

    Apr 2, 2016
    21
    0
    Thank you Wayneh...
     
Loading...