Snubber Heating and transformer noise problem

Posted by: mohan.n2293@gm… on 12/25/2017

Hi PI,

We designed a power supply for 3phase ,but the issue here is we are facing huge noise in the transformer and snubber part is getting heat even with the input voltage 200V AC.

One issue i found is when i measure my transformer leakage inductance(using LCR meter by shorting all secondary at a common point)i got 56uH but as per the PI recommendation leakage inductance should be 30uH.

Please find the attachment for schematic ,drain to source voltage and transformer design details.

Files

Transformer_Details.pdf (310.44 KB)

WhatsApp_Image_2017-12-25_at_4.23.11_PM.jpeg (118.12 KB)

00_3-P_SMPS_Power_Supply.pdf (507.06 KB)

Comments

Please help me in this matter

Hi Mohan,

Which snubber resistor is heating up and the wattage of the resistor? Can you measure the Vrms voltage across the snubber? If the Mosfet has enough Vds voltage stress margin, you can relax the snubbing to make the resistor cooler by reducing the resistance and the capacitance.

For the transformer noise, the windings should be tight and you need to apply varnish to it.

Regards,
PI-Picard

Try PC94 core. Make sure to use epoxy to glue down winding to bobbin and core, not just winding.