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  1. #21
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    Re: Half Bridge LLC Transformer

    LLC Simulation.txt


    I have attached the simulation file.

    I have included Mosfet FCH067N65S3 into the simulation Model. I followed all the steps given in ONsemi document for including the symbol into the library by creating two different folders named ON inside sub & sym folder of lib of Ltspice.

    But it is still showing can't open the library file for the Mosfet while trying to simulate the circuit



  2. #22
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    Re: Half Bridge LLC Transformer

    read the LT Spice help menu, the model has to go into the local LIB folder ....



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  3. #23
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    Re: Half Bridge LLC Transformer

    The symbol file (maybe called xxx.asy) gets dropped into the "sym" folder of ltspice.
    The "sub" file , which has the software for the model, you can paste this into the schematic...and click it and make it a "control" text instead of text.
    There's instructions in the course i sent you...in the "LTspice models" file



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  4. #24
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    Re: Half Bridge LLC Transformer

    I made the simulation work with imported Mosfet & Diode Models. It is working fine now in open loop.

    I am currently designing the feedback loop for closed loop control of LLC resonant converter. Generally EDF(Extended Describing Function) method is widely followed apart from simulation to design feedback loop.

    It is very complex & theoretical to arrive at a closed loop form of relevant transfer functions for LLC using EDF method

    Does anyone have practical experience in designing compensator by any other method???

    Using network analyser on benchlevel testing may be one..



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  5. #25
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    Re: Half Bridge LLC Transformer

    One needs to know all the parameters of the power ckt to design the closed Vout & I limit loops - it is far from a trivial exercise ... even the choice of opto coupler makes a difference ...



  6. #26
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    Re: Half Bridge LLC Transformer

    Quote Originally Posted by Easy peasy View Post
    One needs to know all the parameters of the power ckt to design the closed Vout & I limit loops - it is far from a trivial exercise ... even the choice of opto coupler makes a difference ...
    What do you suggest?? Is it better if try on bench with a network analyser??



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    Re: Half Bridge LLC Transformer

    Sounds good, the AP300 by ridley engineering is good.
    Also, you can supplement with transient response testing...but hold on...this is a battery charger...so there wont really be any transients...so you can go for a nice slow feedback loop. with plenty of phase margin.


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  8. #28
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    Re: Half Bridge LLC Transformer

    Quote Originally Posted by treez View Post
    Sounds good, the AP300 by ridley engineering is good.
    Also, you can supplement with transient response testing...but hold on...this is a battery charger...so there wont really be any transients...so you can go for a nice slow feedback loop. with plenty of phase margin.
    oK..Yes i can go with a very high phase margin.... I guess if the operating frequency is less than resonant frequency(In my case), there are 3 poles & 2 Zeros... The position of whose varies with frequency. How shuld i know the position of individual poles & zeros???

    As i have to design the feedback loop (Both CC & CV)purely based on intuition.

    Type-2 compensator should be ok or Should i go for Type-3(usually for voltage mode control).
    Last edited by biswaIITH; 18th April 2020 at 19:23.



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    Re: Half Bridge LLC Transformer

    There is a feedback loop app note for LLC converters by ti.com....i will try and find it for you....i remember seeing it back in 2011 or so.



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