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Thread: 1kW smps project (based on MicrosiM design)

  1. #1301
    diysmps Senior Member Silvio's Avatar
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    Hi Bad Boy nice job you did there. A bit big just as you said

  2. #1302
    Quote Originally Posted by Silvio View Post
    Hi Bad Boy nice job you did there. A bit big just as you said
    thank you
    I couldn't do it without your help

  3. #1303
    Quote Originally Posted by badboy_6120 View Post
    Hello guys
    Is this ringing on my IGBTs?

    Transformer input:
    Attachment 6476
    I wouldn't exactly call that ringing(although it technically kinda is). That looks more like the primary inductance oscillating in combination with the DC blocking capacitance. I've noticed this waveform across the primary of many regulated/current-protected SMPSs, mostly under zero, or fairly light loads. Although, in a SMPS with over-current protection, this waveform can happen when the limiter kicks in(at heavy load) for a short period of time(just a couple switching cycles).

    We'll start at the horizontal center of your scope screen and move towards the right; here is my best explanation of this behavior. At the center of the screen the primary switches fully negative, passing current for a specified amount of time. After this, it is switched fully positive. Take notice that this positive section is shorter in time than the negative(either imbalance or more likely regulation/ current limiting kicking in). At about 70% of the way through the positive cycle, it appears that switching stops (0% duty-cycle) and both switches are turned off. Since the transformer was passing current at the time when both switches were turned off, the primary's inductance is holding a current charge that needs to go somewhere. This current will cause oscillations across the primary as it dissipates through the switch's freewheeling diodes and the capacitors at the other end of the primary while it finds it's way back to the DC bus. In furthest right column of your scope screen, it appears that the positive switch tried to turn back on to resume switching, but the limit was hit immediately and it turned back off very quickly. In my experience, a snubber across the primary of the transformer will usually stop this type of oscillation from occurring.

  4. #1304
    diysmps Senior Member Silvio's Avatar
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    @ Blasphemy000

    A good explanation and most of it might have occurred. I am not against in all you said but this kind of wave shape was experienced while he was using a snubber across the primary or across the collector and emitter of his IGBTs, I do not know exactly where. He also said that when removing the snubber/s this oscillation was gone.

    It could also be the fact that he has some long lines going from the trafo secondary to the bridge and output caps. This guy split the pcb in two parts as it came rather cumbersome and big and did not fit in one piece. This all might have occurred due to stray inductance disturbing the gate drive.

  5. #1305
    I am not sure if the SMPS was loaded or not when that picture was taken, either I know the running frequency of the converter.
    www.diysmps.com & www.Micro-Audio.com

  6. #1306
    20171217_001453.jpg20171217_001453.jpg i am from indonesia . So iam sorry if my speak is not better . This is my irs2153d half bridge smps and i have a problem . How to regulated output voltage ?? Thank for answer

  7. #1307
    diysmps Senior Member Silvio's Avatar
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    Quote Originally Posted by Nuhrohim View Post
    20171217_001453.jpg20171217_001453.jpg i am from indonesia . So iam sorry if my speak is not better . This is my irs2153d half bridge smps and i have a problem . How to regulated output voltage ?? Thank for answer
    The IR2153 chip is not meant to be regulated.

    I hope that helps

  8. #1308
    Hello
    as our dear friend MicrosiM mentioned the smps was not properly loaded when I took the picture
    so I install the secondary caps and then remove the snubbers and now everything is completely normal
    Thanks anyway

  9. #1309
    Quote Originally Posted by badboy_6120 View Post
    Hello
    as our dear friend MicrosiM mentioned the smps was not properly loaded when I took the picture
    so I install the secondary caps and then remove the snubbers and now everything is completely normal
    Thanks anyway
    That explains everything
    www.diysmps.com & www.Micro-Audio.com

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