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Thread: SMPS with PFC

  1. #41
    diysmps Senior Member res_smps's Avatar
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    I think I have to correct this statement
    Quote Originally Posted by res_smps View Post
    Sorry Silvio,
    With the presence of PFC, capacitor requirements can be smaller, I attach an excel file for PFC calculations (I downloaded from onsemi website) in post # 5
    I thought the PFC frequency determined the size of the capacitor, I was wrong
    from the worksheet, capacitor requirements are not determined by the PFC frequency, please check this formula (pic) below
    cbulk.jpg

    *for the same power, the higher the output voltage the smaller the capacitor needs
    Last edited by res_smps; 10-11-2019 at 02:13 PM.

  2. #42
    *for the same power, the higher the output voltage the smaller the capacitor needs

    In the pfc circuit to my believe the value of the capacitor determines the hold time at load.

    Check this ( I sent you mail)

    NCP1653 Spread sheet Res.pdf
    Last edited by Silvio; 10-11-2019 at 09:56 PM.

  3. #43
    diysmps Senior Member res_smps's Avatar
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    Quote Originally Posted by Silvio View Post
    *for the same power, the higher the output voltage the smaller the capacitor needs

    In the pfc circuit to my believe the value of the capacitor determines the hold time at load.

    Check this ( I sent you mail)

    NCP1653 Spread sheet Res.pdf
    Dear Silvio,

    yes, that also true. Thank you for the file, I also previously shared it here (zip files) in post #2

    please ignore the picture in post #41, there was an error
    cbulk.jpg
    cbulk value is determined from the highest results from the following 2 formulas :
    1) 10000*Pout/(0.01*Vripple*2*pi*Fac*Vout^2
    or
    2) 2000*Pout*Thold/(Vout^2-Voutmin^2)
    from the formula this parameter determines the cbulk
    1. Line frequency (Fac) 50/60Hz
    2. Pout
    3. Tholdup
    4. Vout
    5. Vripple
    Pout and Vout appear in both formula
    Last edited by res_smps; 10-11-2019 at 10:39 PM.

  4. #44
    switchmode-uc3844-2x100v-smps-circuit-schematic.jpg Hello, i think everything is ok about power supply , there is no errors, you can see on this one ..

  5. #45
    Quote Originally Posted by Marshall View Post
    switchmode-uc3844-2x100v-smps-circuit-schematic.jpg Hello, i think everything is ok about power supply , there is no errors, you can see on this one ..
    I guess you want to check the schematic for any errors correct? If that is so please post a larger image of the schematic as it is too small to see it

  6. #46
    About this project , i checked separately every stage , NCP1653 in Data Sheet has same conections as on this schematic only inductor everywhere is 600uH, UC3845 is simple power supply, i share schematic here, connections are good , power stage with SG3525 is also ok , but, things that i dont understand, as i know , this configuration in half bridge main transformer has 13+13 turns in primary , same number of turns also here, i know that full bridge have less windings than half brigde , maybe 2 X 7.. that its not clear, also inductor 380uH vs. 600uH !? , number of turns on transformer on aux supply !? and windings on GDT !?.. PHOTO.jpg
    Attached Images Attached Images
    Last edited by Marshall; 12-05-2019 at 11:29 AM.

  7. #47
    diysmps Senior Member
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    hi andrew . did you manage to make your smps work succesful with the pfc? please post photos and your experience on its power.

  8. #48
    Quote Originally Posted by Silvio View Post
    Hi Michelle, Do not be mislead the video in the first post shows a full bridge smps while you are building a half bridge smps. As I can see the pcb takes two kinds of transformer. It either takes an EE55 or an ETD49. The EE55 gives a little more power in fact I got 2KW in my prototype with EE55. ETD49 will give you around 1.5Kw. You must also consider the input voltage with the PFC will be always higher than the maximum AC input voltage.

    Let us say that the maximum input voltage of the smps is 254vac then rectifying and smoothing will bring a voltage of around 360vdc. Usually we settle for a voltage of 380-400v. Please also consider your nominal input AC voltage at home and if it is on the lower side like 210vac or lower then it will be better to settle for around 370v or so. I am saying this because the PFC will have enough headroom to boost up the voltage when high load is present.

    With all this in mind please let me know what transformer you are going to use and also the core material so that I can work out the number of turns for you. Please also let me know the output voltage wanted. I will also want to know the bobbin length and the window space so that I can calculate how the winding will fit in the transformer. The switching frequency will be adapted according to how things will fit and copper wire used. Please also tell me what switching transistors are you going to use as I have to put the saturation voltage or the RDS on in the software. I also want to know what output diodes for the output you are going to use. I am assuming that this smps is going to be used for audio amplifier.

    Regarding the PCB I think all is well and as you start assembling things I will guide you step by step so that you will not blow anything up.
    Yes I am on facebook and also watsup. send my an email on silviodeleo@gmail.com and I
    give you details.

    Here is the link for the HB smps you are building https://www.youtube.com/watch?v=_MHwd7Ro27g&t=1s

    Regards Silvio
    Dear Silvio , I hope that you are doing well and everything is ok with you.

    I have ordered the same pcb and components and would like to make this HB PFC of 2 kW with EE55 like your prototype. I will really appreciate if you can share me with the windings of the EE55 transformer please with AUX and possibly FAN output and B2 Sanken pwm supply transformer.
    My e mail adress is ferhanka@gmail.com. I thank you alot in advance.
    Regards,

  9. #49
    Quote Originally Posted by vision4u View Post
    Dear Silvio , I hope that you are doing well and everything is ok with you.

    I have ordered the same pcb and components and would like to make this HB PFC of 2 kW with EE55 like your prototype. I will really appreciate if you can share me with the windings of the EE55 transformer please with AUX and possibly FAN output and B2 Sanken pwm supply transformer.
    My e mail adress is ferhanka@gmail.com. I thank you alot in advance.
    Regards,
    Regarding the primary windings they are clearly listed in the video so for EE55 it has 12 turns for operation at 65Khz. You will have to tell me what is the output voltage needed in your power supply.

    For an output of the pfc we can settle out for a voltage of 380v so half of this will be the input to the half bridge ( what the transformer sees in its primary) we will calculate the volts per turn

    380v / 2 = 190v So to find the volts per turn we divide 190v/ 12 turns = 15.8v

    So to calculate your secondary turns you will use 15.8v per turn.

    Regarding the sanken auxiliary PWM transformer I guess this is bought ready made and I do not know its number of turns.

    Regards Silvio

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