ZVS Mazzilli circ with active gate driver - what causes ringing?
erkone, Sun May 19 2019, 07:26PMHi all,
Trying to make ZVS mazzilli circuit with active gate driver and getting bad ringing at switch over. While trying to debug it, found most noisy point to be on collector of Q401(Q402).
Here is my circuit attached with scope traces of that point and of ouputs. Could somebody experienced give a hint what causes this ringing and how to fight it?
Re: ZVS Mazzilli circ with active gate driver - what causes ringing?
erkone, Sun May 19 2019, 07:34PM
For some reason circuit pictures was removed from this post. Cicruit, scope screens and pcb layout can be found on highvoltageforum(dot)net forum under the topic with same name as this
erkone, Sun May 19 2019, 07:34PM
For some reason circuit pictures was removed from this post. Cicruit, scope screens and pcb layout can be found on highvoltageforum(dot)net forum under the topic with same name as this
Re: ZVS Mazzilli circ with active gate driver - what causes ringing?
flyrod, Sun May 19 2019, 08:28PM
I saw your thread over there, but I'm blocked for they day...
So, what does the signal on the other end of R408 look like?
The reason I ask is because I don't see any bypass caps in your diagram. If you see noise there, then try adding some. The Q403/Q409 totem pole controls the gate, so it should have a low inductance bypass cap directly across it to supply the charge that gets transferred to the gate.
Are you using the circuit board from that article? They have a bunch of caps very close to the gate control, although their proximity is not obvious in their schematic.
Also, you could check R410/R411. Make sure it is small, and you could try making it smaller. What do you see if you just short it?
flyrod, Sun May 19 2019, 08:28PM
I saw your thread over there, but I'm blocked for they day...
So, what does the signal on the other end of R408 look like?
The reason I ask is because I don't see any bypass caps in your diagram. If you see noise there, then try adding some. The Q403/Q409 totem pole controls the gate, so it should have a low inductance bypass cap directly across it to supply the charge that gets transferred to the gate.
Are you using the circuit board from that article? They have a bunch of caps very close to the gate control, although their proximity is not obvious in their schematic.
Also, you could check R410/R411. Make sure it is small, and you could try making it smaller. What do you see if you just short it?
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