TIDA-00173: customized the transformer of TIDA-00173

hello,

good day!

 I customized  the transformer of TIDA-00173 for my application to have :

    4 separate output for IGBT driver power 

1.GND_U VCC_U

2.GND_V VCC_V

3.GND_W VCC_W

4.GND_E VCC_E

one output for fan

5.GND_24 VCC_24

one  output for  function board 

6.GND_FNC VCC_FNC

one  out put for AUX ...

7.GND_AUX VCC_AUX

in put  voltage is 620VDC.

but sadly, It had very Spike in all of out puts.

so I came up with an idea to put capacitor (10nf 1000v) from HV+ coil pin to all of Ground pin in outputs (6 capacitor in total) .

in other word

C1(10nf 1000v) between  +HV ,GND_U

C2(10nf 1000v) between +HV ,GND_V

C3(10nf 1000v) between +HV ,GND_W

C4(10nf 1000v) between +HV ,GND_E

C5(10nf 1000v) between +HV ,GND_FNC

C6(10nf 1000v) between +HV ,GND_24

it works good ,and now my outputs have a small spike,

so,my question is that :

1. if is that wrong to put capacitor between primary coil and  all of secondary coils or not?

2.(as you know the IGBT driver powers must be separated from each other ),so those capacitor does have bad effect?

3.since it is customized transformer what else we can do to reduce the noise sound and spike of it.

thanks for attention .

Dave.