Bidirectional DC-DC Converter

Discussion in 'The Projects Forum' started by BramLabs, Oct 7, 2016.

  1. BramLabs

    Thread Starter Member

    Nov 21, 2013
    Hello sir,

    I want to ask about the operation of this bidirectional DC-DC Converter that i found in the internet ( ).


    First in buck mode, the current goes through like this (Switch 1 ON ; Switch 2 OFF) :

    And then, when Switch 1 OFF and Switch 2 OFF, the current goes through like this :

    What i want to ask sir is that does the current flow to Diode D2 EVEN the Switch 2 is in OFF state like i did in my picture above ?

    Because i was wondering at the Boost Mode, i was confused because of in the boost mode, when the Switch 2 is in ON state, the current also goes through the diode 1 even if S1 is in OFF state :

    Am i right sir ?

    And then i want to ask about the calculation for getting L1 and C1. I'm looking everywhere but couldn't find it T__T

    Oh yeah, if there any conventional Bi-directional buck-boost converter circuit, please mention in the comment below, it really helps me to get the information about the converter.

    Thank you before.
    Last edited: Oct 7, 2016
  2. DickCappels


    Aug 21, 2008
    BramLabs likes this.
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    MOSFETs have intrinsic body diodes (which you have to allow for), as represented by D1 and D2. Current will flow in these even when the MOSFETs are switched off.
  4. BramLabs

    Thread Starter Member

    Nov 21, 2013
    Thank you sir for your information, even there's slightly different with the circuit, i think the calculation can be used.

    Yeah, so basically, the circuit is not right ?
    Thank you btw for your reply.