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DC / AC Inverter Design Assistance

Discussion in 'Electronics Homework Help' started by Iskandar, Sep 2, 2016.

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  1. Iskandar

    Iskandar

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    Sep 2, 2016
    Hey guys, I am kinda new in power electronics and I have a task at hand that requires assistance.

    I have an assignment to build a SMPS. My prof gave me a breakdown that once I rectify the Input from AC (230V rms), 50Hz to a DC (300V), I need to channel the output through a DC / AC Inverter. I have been searching the net for a pretty beginner level decent explanation on the principle of operation but I got confused along the way. I have come across the fundamentals of the SMPS Flyback Converter. Is that a better option to use instead?

    Here is the block diagram from my prof

    Rectify from Mains -> DC/AC Inverter -> Transformer -> Rectify -> 2 outputs , (12V, 5A),
    Thanks in advance
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Consider whether you need isolation.

    Which topologies will give you that?
     
  3. Iskandar

    Iskandar

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    Sep 2, 2016

    Hi Steve, my application would be ideally, to power up the television that requires about 100 to 120 watts. So Im guessing it should be isolated switch mode power supply.
    I have seen quite a variant of SMPS, Im' guessing the Flyback Converter as it introduces a transformer and it allows multiple output in the secondary side by just introducing extra windings.
    Im confused why did my prof clearly defined a DC/AC inverter. Hope my doubts can be clarified. Thank you
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Look at a basic description of why smps power supplies are used, and how they operate.

    The transformer you mentioned is a big clue.
     
  5. Iskandar

    Iskandar

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    Sep 2, 2016
    The reason smps are much favoured instead of linear regulators is because to improve efficiency and to improve cost and design. Am I safe to say I have been fooled into thinking that I needed to build a DC/AC inverter when I can just build a simpler circuit based on the Flyback Converter that can essentially solve the problem? I apologise for my lack of knowledge, kinda new into this power electronics stuffs.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    You've noted that the fly back design requires a transformer. Can these operate from DC?

    What are the differences between transformers used in linear power supplies vs those in switch mode power supplies?
     
  7. Iskandar

    Iskandar

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    Sep 2, 2016
    My apologies, a transformer cannot be used to step up/ step down a DC voltage. It can only be done with an AC voltage. The transformer that was mentioned in a flyback converter actually uses a inductor that was split to act a transformer, saving space.
    Moving forward, can I clarify,

    1. The rectified DC output (300V DC) I have to inevitably convert to AC using the inverter. But is it possible to receive a 300V DC and convert to an AC, thus I can't seem to grasp the concept of DC/AC inverter, find any cause I only managed to find low voltages (12V for example) to (240V for example)
    2. I do not need a Flyback Converter at all then ?

    Sorry for the long post. I hope you are patient with me. Thank you.
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Perhaps if you google "how does a switch mode power supply work"...?
     
  9. Iskandar

    Iskandar

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    Sep 2, 2016
    I guess my fundamentals is screwed up. I shall look into it again. Thank you
     
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