+ Post New Thread
Results 1 to 5 of 5
  1. #1
    Advanced Member level 5
    Points: 32,326, Level: 43
    Achievements:
    7 years registered

    Join Date
    Sep 2008
    Location
    cambridge
    Posts
    6,734
    Helped
    488 / 488
    Points
    32,326
    Level
    43

    High voltage input linear regualtor using IGBTs?

    Hi
    We are doing a high voltage linear regulator to run off rectified 240VAC.
    The following two schematics are our possible choices.
    They would more cheaply be done with the FET replaced with a IGBT. What do you think of low current linear regulators using IGBTs?

    (Output is 3V, 6mA max in each case)

    LTspice sim also attached

    •   AltAdvertisement

        
       

  2. #2
    Super Moderator
    Points: 76,224, Level: 67
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    15,460
    Helped
    3515 / 3515
    Points
    76,224
    Level
    67

    Re: High voltage input linear regualtor using IGBTs?

    Hi,

    3V, 6mA calls for a capacitive AC supply.
    Otherwise a linear supply may dissipate about 2W.

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  3. #3
    Advanced Member level 5
    Points: 32,326, Level: 43
    Achievements:
    7 years registered

    Join Date
    Sep 2008
    Location
    cambridge
    Posts
    6,734
    Helped
    488 / 488
    Points
    32,326
    Level
    43

    Re: High voltage input linear regualtor using IGBTs?

    Thanks yes you are right, i should have said the 6mA is only when DALI is transmitting...which isnt often, most often the current draw is around 1.4mA.



    •   AltAdvertisement

        
       

  4. #4
    Super Moderator
    Points: 258,478, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    45,127
    Helped
    13718 / 13718
    Points
    258,478
    Level
    100

    Re: High voltage input linear regualtor using IGBTs?

    They would more cheaply be done with the FET replaced with a IGBT.
    Why do you think so?


    1 members found this post helpful.

  5. #5
    Super Moderator
    Points: 52,307, Level: 55

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    12,829
    Helped
    2554 / 2554
    Points
    52,307
    Level
    55

    Re: High voltage input linear regualtor using IGBTs?

    It sounds as though you need only 1.4 mA most of the time? Then it may be possible to store some juice for your infrequent 6mA load in a large capacitor. Install a resistor to provide some isolation. Then it charges over a period of time by stealing just a tiny amount of current.

    My simulation has no IC's nor transistors nor mosfets.

    Mains 230VAC is dropped through 40k resistor and 160V zener diode (in series it drops 160V). You might get by with 1/2W rating since they dissipate 0.7W at less than 50 percent duty cycle.

    The 160v zener diode may need to be assembled from lesser values.

    I detached the 3.3V zener to demonstrate that usable volt and Ampere levels can be obtained, by adjusting values and watching results.

    Click image for larger version. 

Name:	230VAC dio bri dropped via 160v zener 40k resis to 3VDC load 2k switched load 500.png 
Views:	9 
Size:	52.3 KB 
ID:	151073

    The 6mA load has its own large reservoir capacitor. They are isolated via 10k resistor. It takes a few minutes to charge to 3V. When you press the switch it discharges in about 1/10 second. (If you need longer On time then you can increase the reservoir capacitor to whatever size is necessary.)

    Since the 6mA section draws a tiny amount of juice from the normal load, the normal load does not drop below 2.9v.


    1 members found this post helpful.

--[[ ]]--