TIDA-00951: TIDA-00951 Operation method inquiry

Lewis Kevin

Part Number: TIDA-00951

TIDA-00951 There are some questions about the design board.
The HV side FET is described as full bridge driven.
However, there is no working waveform for the FET when in charge mode.
Is it Phase Shift?
Or is it traditional Hard Switching?
And does the LV side FET operate with synchronous rectification?

Here is the Center tap question for Trans.
In the circuit diagram, it is connected to the center tap of Trans primary side and the capacitor center. What does it do?
Or what are the benefits?

Here are some questions about Boost Mode Working: Cold Start.
Can I remove the cold start circuit if the HV capacitor is always maintaining a voltage above 350V?

Thank you for your help.

over 4 years ago

0 Desheng, Guo over 4 years ago

TI__Expert 5920 points

Hi, Bea

Sorry, I am on business travel now.

I will check your questions this night, thanks.

0 Lewis Kevin over 4 years ago in reply to Desheng, Guo

Intellectual 500 points

I will wait..

Thank you.

0 Desheng, Guo over 4 years ago

TI__Expert 5920 points

Hi, Bae Su-min

I do not know what does you mean by "no working waveform". Where you tested, and which signal?

I think you can do some simulation with this topology, and You can refer the design guide to study the circuits operation process. http://www.ti.com/lit/ug/tidud04/tidud04.pdf

at last, I think you can remove the cold start circuits.

0 Lewis Kevin over 4 years ago in reply to Desheng, Guo

Intellectual 500 points

Hello

Thank you for yor reply.
I think that my inquiry was not enough detail.

Please kindly check again my further question.

1) From TIDA-00951, I cannot find waveform about FET operation on HV Side.
Could I get 'waveform data'of Q7~Q9 operation from Figure 3 with Charge mode.
if you do not have this waveform data, could you explain about "FET operation on HV Side" to me?

2) Another question is about the role of Center Tap of T1 from Figure 3.
TIDA-00951 states Full Bridge method.
I am wondering the reason why Center Tap of T1 is connected to C1, C2 center...

Thank you for your prompt reply in advance.

0 Ramkumar S over 4 years ago in reply to Lewis Kevin

TI__Intellectual 2815 points

Hi,

For the questions:

1) The TIDA-00951 in Charger mode operates as hard switched full-bridge. Firgure 17 in the design guide shows this operation.

2) The center tap is provided for applications that need a +200V and -200V rail (like a half-bridge inverter). This also allows with the proper transformer modification a +400 and -400v rail for 230V output half-bridge inverter applications.

Best Regards,

Ram

0 Lewis Kevin over 4 years ago in reply to Ramkumar S

Intellectual 500 points

Thank you for your kind reply.

I have a additional question about your reply No.2).

I understand that TIDA-00951 in Charger mode operates as full-bridg.
Then, This means that there is no situation to operate as Half-bridge in TIDA-00951 and Could I understand that Center tap does not need to be connected accordingly?
otherwise, Is there a certain section to operate as Half-bridge?

Thank you!

0 Ramkumar S over 4 years ago in reply to Lewis Kevin

TI__Intellectual 2815 points

Hi,

Yes. You only need to connect the center tap, If you want to connect a half-bridge inverter at the output of this board. Otherwise you can disconnect the center tap.

Best Regards,

Ram

0 Lewis Kevin over 4 years ago in reply to Ramkumar S

Intellectual 500 points

Thank you for your replay~

Have a nice week.

0 Madhu Joshi over 4 years ago in reply to Lewis Kevin

Prodigy 40 points

Hi Ram,

I was wondering how ZVS is achieved if the charger is in hard switched? If you could elaborate on buck mode, it will be very helpful. Are there any related design notes? How is the current controlled? Is it peak current? Please elaborate.

Thank you

0 Desheng, Guo over 4 years ago in reply to Madhu Joshi

TI__Expert 5920 points

Hi, Bae

I have checked this with Ram, for the charge mode, its operation is simply full bridge PWM;

High voltage side is hardswitch, so it is non ZVS; the low voltage side, its works in SR mode, it is ZVS.

Hope it solved your question. thanks.

0 Madhu Joshi over 4 years ago in reply to Desheng, Guo

Prodigy 40 points

Thank you for the response. How are gate signals on the low voltage side derived in buck mode? Are MOSFETs conducting ? How does SR mode work?

I appreciate further details.

0 Desheng, Guo over 4 years ago in reply to Madhu Joshi

TI__Expert 5920 points

Hi, Madhu

you can refer to the fig.17 in the design guide.

it shows, it is works in hard switching PWM mode, and LV side MOSFET can be seen as diode.

0 Madhu Joshi over 4 years ago in reply to Desheng, Guo

Prodigy 40 points

Hello Again,

Thank you for the response. When you said SR mode, I assumed Sync Rectification on LV side. So, looks like you are keeping MOSFETs off and only using diodes? Please confirm. If this is not true, how are the gates generated for LV side with reference to HV side?

Best regards,

0 Desheng, Guo over 4 years ago in reply to Madhu Joshi

TI__Expert 5920 points

Hi, Madhu

The LV side does not only using diodes, the gate will be driven high to reduce the conduction loss of MOSFET's diodes.

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TIDA-00951: TIDA-00951 Operation method inquiry