Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

center tap transformer

Status
Not open for further replies.
R

ravit245

Junior Member level 2
Joined
Oct 27, 2011
Messages
22
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,425
hi,
here i am using a 28vdc voltge at center tap of primary,as far as i know the voltage at top switch wrt to center tap should be +28v-0v.but the voltage is +/-28v.
centertap.pngcentertap.png
plz explain me.
 

Attachments

  • centertap.pdf
    11.7 KB · Views: 55

as far as i know the voltage at top switch wrt to center tap should be +28v-0v.but the voltage is +/-28v.
Click to expand...
Your assumption does hardly comply with the know property of a transformer respectively inductor to have zero average DC voltage across it.

Ideal Vds of the MOSFETs will be in fact minimum 0 V, maximum 56 V in your circuit.

P.S.: I have some difficulties to imagine the operation of your (secondary) PWM circuit. Can you provide a scheme of intended waveforms?
 
Last edited:

There are at least 3 output pins from a center tap transformer. We have the + lead, the - lead and the center tap. Depending on what you want you can get. The + and center tap gives you +28 - 0v. the - and center tap gives you -28 and 0v, the + and - gives you +28 and -28V which is equivalent to +56 0v. your connection works on the third case which I suspect is not your design. So you may alter your design to use one of the first 2 cases or buy a 14v - 0 - 14v center tap transformer

opopson
 

Your observation is correct. Each end of primary will be +/- 28 volts with respect to center tap.

Primary winding acts as autotransformer, so with +28vdc on center tap, when one end goes low the other end goes to twice the center tap voltage (56 volts). (minus whatever MOSFET On state Vds voltage drop is for given Ids current).

Why do you need bidirectional switches on secondary?

The circuit is prone to DC core bias buildup on transformer without some mitigating correction.
 

please go thru uspatent 4479175
 

Attachments

  • waveforms.png
    waveforms.png
    115 KB · Views: 63

please go thru uspatent 4479175
Click to expand...
O.K., I understand the phase modulation idea. Basically, it's another way to implement a sine PWM. I assume, the ramp voltage range is -2V to +2V? Personally I would prefer a more reliable method than clocking the DFF with the comparator output, but it should work if designed properly. Any questions left?
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top