adnan012
Advanced Member level 1
hi,
I am using UCC28950 in a full bridge converter (without ZVS). Here are the specs
Input 385 VDC (from PFC)
Out Put Voltage 28VDC
Output current 29A
Converter primary switching frequency is 100Kz
I am using RM14 C95 core. and following the schematic given in the datasheet and using the excel sheet calculator.
I can test the DC/Dc converter for 30 min. At the start transformer generates some sharp noise. Transformer temperature rise to 80C an i need to place a fan near it.
After 30 min secondary side synchronous FET get damaged.
I want to discus the transformer design. If the calculated primary magnetizing inductance (using UCC28950 Excel Design Tool_SLUC222C.xls) is 2mH, is it possible to make primary 7mH or even large? I am also using ansys PExprt tool to design transformer and it always give high primary inductance then " UCC28950 Excel Design Tool_SLUC222C.xls".
Pexprt gives 39 primary turns with 13mH magnetizing inductance (turn ratio is 9)). " UCC28950 Excel Design Tool_SLUC222C.xls" gives 1.94mH magnetizing inductance. Which design should i follow?
Second i have to place 20 ohm resistor (connected to the CT transformer) to run the converter. The design sheet gives 36 ohm.
Regards
I am using UCC28950 in a full bridge converter (without ZVS). Here are the specs
Input 385 VDC (from PFC)
Out Put Voltage 28VDC
Output current 29A
Converter primary switching frequency is 100Kz
I am using RM14 C95 core. and following the schematic given in the datasheet and using the excel sheet calculator.
I can test the DC/Dc converter for 30 min. At the start transformer generates some sharp noise. Transformer temperature rise to 80C an i need to place a fan near it.
After 30 min secondary side synchronous FET get damaged.
I want to discus the transformer design. If the calculated primary magnetizing inductance (using UCC28950 Excel Design Tool_SLUC222C.xls) is 2mH, is it possible to make primary 7mH or even large? I am also using ansys PExprt tool to design transformer and it always give high primary inductance then " UCC28950 Excel Design Tool_SLUC222C.xls".
Pexprt gives 39 primary turns with 13mH magnetizing inductance (turn ratio is 9)). " UCC28950 Excel Design Tool_SLUC222C.xls" gives 1.94mH magnetizing inductance. Which design should i follow?
Second i have to place 20 ohm resistor (connected to the CT transformer) to run the converter. The design sheet gives 36 ohm.
Regards