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Why Flyback and Forward Converts aren't used in high power applications

Discussion in 'General Electronics Discussion' started by plainwhite456, Jan 25, 2019.

  1. plainwhite456


    Jan 25, 2019
    Hello all,

    I am currently researching different converter topologies, and frequently come across the statement that forward and flyback isolated converters can achieve intermediate power output levels of approximately 100-200W. However, much less frequently, do I see any explanation as to why this is the case. I am looking to design a converter with a total power output of 500W+, and thus would like to definitively rule out the use of these converters. Again, many say that they can be used in such applications but the efficiency at these powers causes this design choice to be poor, while offering not much explanation as to why. I would be very grateful if someone could clear this up for me.

  2. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    Efficiency at various power levels for various circuit topologies is extremely variable. There is no general answer to your inquiry. A given transformer, for example, may exhibit 98% efficiency meaning only 2% of the input power is converted to waste heat while 98% is converted to an appropriate voltage and current capability. However, the actual power lost to conversion inefficiency depends on how much load the transformer is driving. Clearly, if only very small loads are driven, and losses remain constant, the losses will be much greater than the power expended in the load leading to very low efficiency even though the transformer is capable of much higher efficiency.

    The observations in the previous paragraph are applicable to any converter topology. An engineer will choose the topology that best suits the problem, and it may turn out that this topology is unavailable or is very expensive to implement at the required power levels. Unavailable is not the same as expensive, so if cost is no object (certain government projects) an inappropriate topology may be selected for reasons other than efficiency. Most projects need to balance SWAP (size, weight, and power) requirements against cost, but unrealistic requirements can make any solution a non-starter at any cost.
    Arouse1973 likes this.
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