Selecting Bidirectional DC/DC Converter

Discussion in 'The Projects Forum' started by boiledbeans, Sep 5, 2014.

  1. boiledbeans

    Thread Starter New Member

    Sep 5, 2014
    Hi, I'm relatively new to this field and I am trying to select a bidirectional DC/DC converter for a project.

    The general idea of my project involves an electric vehicle (EV) powered by a battery and ultracapacitor which are linked to the DC bus by one or two DC/DC converters (depending on the configuration). So I require bidirectional DC/DC converters, which are controllable by a microprocessor (PWM). It needs to be controllable because I want to control the power output for the battery and ultracap.

    So here are the specs required for a small scale project.

    - DC-link side voltage input/output: constant 24V, max 3.5A

    - Ultracap side voltage input/output: approx. 5V-17V varying

    (This would mean buck in one direction and boost in the other)

    - Non-isolated converter is sufficient.

    I have tried looking at the Texas Instruments and Linear Technology websites, but there are too many choices and I don't know how to select one. Maybe you can point me to the right category to select such a converter.

    I have another general question. For a battery or ultracap connected to a DC link via a DC/DC converter, why is the battery or ultracap voltage lower than the DC link voltage in general?

    My original plan for this project was for the ultracaps to be at 32V and DC link at 24V. But I couldn't find converters to do buck/boost in both directions. So I looked at some existing systems and found that the DC link voltage is usually higher than battery & ultracap. Why is this so?

    Thanks in advance for any help!
  2. boiledbeans

    Thread Starter New Member

    Sep 5, 2014
  3. DickCappels


    Aug 21, 2008