ground plane noise in v/f drive circuit

[samic45mit1]

I am working on three phase v/f sclar drive and using semikron skyper32r IGBT driver. The drive work fine and motor speed is controlling as desire. But I also measuring input voltage and current form rectifier (dc output), before feeding it to IGBT. And here the problem come, there is high frequency noise in ground plan. the opamp circuit I use effected by this noise and result is not proper.For current measurement I use ferrite core current transformer and for voltage i use voltage divider .I average the voltage and current value in microcontroller but only small improvement. I use dspic33fj64mc706 microcontroller. The noise pp voltage is 3V. And there is no dout that the noise is coming for skyper 32r. My dead time is 2us given form microcontroller register's and PWM is 20KHz. I try everthing like capacitor and LC filter but they not work because noise is in ground plan. I use adapter Board 1 SKYPER 32 R and connect all component as given in data sheet.I also contact semikron person but there answer is that they never test there board's on any dynamic load. So please help me to solve this problem.

 

[KlausST]

Hi,

Show schematic, layout and scope pictures. Please add voltage and timing values.

Klaus

 

[samic45mit1]

Please see the image of noise. Here ground noise is probeum.

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Please see the image of noise. Here ground noise is probeum.View attachment ckt1.bmpView attachment ckt1.bmp

 

[D.A.(Tony)Stewart]

It certainly looks noisy. Check using a probe with gnd and clip removed using only tip & ring between 2 pins a few mm apart.
verify all Vref DC and feedback voltages are clean. Use twisted pairs , if you dont have a ground plane and keep interconnects very short. Use low ESR caps to suppress current pulse noise where needed and small ferrite beads on Gate drive if necessary.

Observe stray capacitance resonance during dead band switching.

Keep all wiring neat and short paths ( ~1cm ) for the closed loops.

 

[samic45mit1]

I already try ferrite beads to remove noise,But result are not good. As I already told the noise source is skyper32r. The Noise come form ground track,so using capacitor filter is useless (I already try). And ground noise effect the operation of op amp. Ans I try with twisted pair and d as you told cable length between sky per and main board is about 6 cm. One more thing, I disconnect high voltage supply with rectifier and only start the PWM, even then noise is coming.

 

[KlausST]

Hi,

Schematic and PCB still missing.

Klaus

 

[samic45mit1]

Schematic is attached but I can't provide PCBView attachment ckt1.bmp