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Old 5th February 2011, 11:46 PM   #1
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Default Ringing on class d output inductor.

I am getting around 35 volts overshoot then ringing on my class d output inductor.
Is there any way to reduce this ?

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Old 6th February 2011, 06:50 AM   #2
luka is offline luka  Slovenia
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is this after inductor?
could be that core is saturated.
was this with any input signal?
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Old 6th February 2011, 01:25 PM   #3
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is this after inductor?
could be that core is saturated.
was this with any input signal?
This is before the inductor.
I am using a 16 amp indcutor so it shouldnt be saturating.
The power supply is only a 2 amp supply.
This was without an input signal.
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Old 6th February 2011, 02:28 PM   #4
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peak current comes from caps, 2a is a lot from that point of view. can you post after inductor, am thinking cross-conduction could be going on, or bad layout/inductive elements, if you have any resistors before fets(i don't think so)
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Old 6th February 2011, 02:50 PM   #5
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Originally Posted by luka View Post
peak current comes from caps, 2a is a lot from that point of view. can you post after inductor, am thinking cross-conduction could be going on, or bad layout/inductive elements, if you have any resistors before fets(i don't think so)
There is a 470nf capacitor after the inductor.

Deadtime is 125nS, I tried 25ns but it made no difference to the problem.

The mosfet gates have a 10R before them.

I put two inductors in series just to try it and there is a slight improvement.
I have ordered a 28 amp inductor to see if that helps.
The inductor gets very hot around 120 degree C.
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Old 6th February 2011, 03:44 PM   #6
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really, that hot?
i cant say that inductor is saturating, but it is a possibility
could be that it is wrong material
what is the inductance? and switching freq?
load connected?
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Old 6th February 2011, 03:54 PM   #7
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Hi,
Please...change material of toroid.
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Old 6th February 2011, 03:54 PM   #8
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really, that hot?
i cant say that inductor is saturating, but it is a possibility
could be that it is wrong material
what is the inductance? and switching freq?
load connected?
It is a toroid 22uh and 16amps.
Odd thing is my supply is just a bench supply that gives out 2 amps so I cant see why any overcurrent is being triggered unless it is drawing very narrow pulses from the smoothing capacitors.
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Old 6th February 2011, 03:57 PM   #9
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Hi,
Please...change material of toroid.
I am currently using this toroid.
BOURNS JW MILLER|2305-V-RC|TOROIDAL INDUCTOR | Farnell United Kingdom
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Old 6th February 2011, 04:01 PM   #10
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Quote:
Originally Posted by nigelwright7557 View Post
It is a toroid 22uh and 16amps.
Odd thing is my supply is just a bench supply that gives out 2 amps so I cant see why any overcurrent is being triggered unless it is drawing very narrow pulses from the smoothing capacitors.
correct, i drive 350w on output, yet i have 130w max supply, most of the power comes from caps

what material did you use
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