[SOLVED] Half bridge power supply

[gb_R]

I'm trying to make a half bridge power supply . after a year of learning, now every thing looks perfect when i run it at 45V DC bench power supply but when i run it on mains (240AC) the low side IGBT get hotter then the high side one ( I don't have a temp meter at the moment but it looks x2 times hotter then high side one when i touch the heatsink ). I swap the IGBT and the other components low side to high side but the issue always stays on the low side. GDT voltage and signals are same on both side. only the difference is the low side IGBT to GDT tracks are about 3cm longer then the high side one. could that be the reason ? ( every thing looks perfect when i run it at 45V DC bench power supply, both IGBT equally warm ). Regards

 

[KlausST]

Hi,

A half bridge is made to run from DC ... I am not surprised that it does not work on AC.

GDT voltage and signals are same on both side.

I would be very suprised if this is true.

***
We don´t know what "perfect" means in your case.
We don´t have a schematic to check correctness.
We don´t have datasheets of the used parts.
We don´t have scope pictures to see signals and their timing.
We don´t even know what´s the power supply specification regarding output and input.
We even don´t know what the HIGH side and what the LOW side IGBT is on the given picture.
We don´t see the PCB layout ... like GND plane and low inductance wiring, current loops sizes and so on.

Without knowing anything about your power supply ... it´s impossible to help.

Klaus

 

[gb_R]

Hi,

A half bridge is made to run from DC ... I am not surprised that it does not work on AC.


I would be very suprised if this is true.

***
We don´t know what "perfect" means in your case.
We don´t have a schematic to check correctness.
We don´t have datasheets of the used parts.
We don´t have scope pictures to see signals and their timing.
We don´t even know what´s the power supply specification regarding output and input.
We even don´t know what the HIGH side and what the LOW side IGBT is on the given picture.
We don´t see the PCB layout ... like GND plane and low inductance wiring, current loops sizes and so on.

Without knowing anything about your power supply ... it´s impossible to help.

Klaus

 

[gb_R]

For now i want to make sure, the IGBTs must be equally far from the GDT or that 3cm differences shouldn't make any problem unless otherwise ? here is the pcb layout. i will upload other information soon. Regards

 

[cupoftea]

hi,
you do half bridge but remember they go out of balance when done in
current mode.

This has been discussed many times on this forum before....try a google search of "edaboard easy peasy half bridge"
Easy Peasy has good info on this.

Current mode Half Bridge converter.

Hi, We all knew that Half Bridge shouldnt be done in Current Mode. But with software to guide it, Current mode becomes possible. You simply repeatedly measure the voltage on each of the series stacked capacitors....(by using two potential dividers)...and then you slightly adjust the alternate...

www.edaboard.com

Voltage Mode Half Bridge made easier.

We are doing a 3kW Half bridge converter. Vin 600V, vout = 24v. Done in voltage mode for obvious reasons. (Split cap balancing etc) Cant we just find the output LC resonant frequency....(which is also the frequency of the troublesome output double poles). So then all we do is find the Output...

www.edaboard.com

It always used to be said that a dc blocking cap was needed
when in voltage mode. Then the voltage build up on the blocker will oppose the
off balancing factor. But be sure your cap blocker is not too big. You need it
to show some voltage change during the cycle on time.
Anyway, current mode with slope compensation also can be workable with
half bridge.
Also, some people do extra circuits to detect the imbalance, and then reduce
one of the gate drives minutely, so as to even things back up again...but generally
, nobody bothers with that and just does a 2 tran forward instead.

 

[gb_R]

hi,
you do half bridge but remember they go out of balance when done in
current mode.

This has been discussed many times on this forum before....try a google search of "edaboard easy peasy half bridge"
Easy Peasy has good info on this.

Current mode Half Bridge converter.

Hi, We all knew that Half Bridge shouldnt be done in Current Mode. But with software to guide it, Current mode becomes possible. You simply repeatedly measure the voltage on each of the series stacked capacitors....(by using two potential dividers)...and then you slightly adjust the alternate...

www.edaboard.com

Voltage Mode Half Bridge made easier.

We are doing a 3kW Half bridge converter. Vin 600V, vout = 24v. Done in voltage mode for obvious reasons. (Split cap balancing etc) Cant we just find the output LC resonant frequency....(which is also the frequency of the troublesome output double poles). So then all we do is find the Output...

www.edaboard.com

It always used to be said that a dc blocking cap was needed
when in voltage mode. Then the voltage build up on the blocker will oppose the
off balancing factor. But be sure your cap blocker is not too big. You need it
to show some voltage change during the cycle on time.
Anyway, current mode with slope compensation also can be workable with
half bridge.
Also, some people do extra circuits to detect the imbalance, and then reduce
one of the gate drives minutely, so as to even things back up again...but generally
, nobody bothers with that and just does a 2 tran forward instead.

Thank you very much. That is what i was thinking about. ill try putting some resistors on both dc blocking cap. i've seen that on some power supply. ill also try replacing another caps.

 

[gb_R]

hi,
you do half bridge but remember they go out of balance when done in
current mode.

This has been discussed many times on this forum before....try a google search of "edaboard easy peasy half bridge"
Easy Peasy has good info on this.

Current mode Half Bridge converter.

Hi, We all knew that Half Bridge shouldnt be done in Current Mode. But with software to guide it, Current mode becomes possible. You simply repeatedly measure the voltage on each of the series stacked capacitors....(by using two potential dividers)...and then you slightly adjust the alternate...

www.edaboard.com

Voltage Mode Half Bridge made easier.

We are doing a 3kW Half bridge converter. Vin 600V, vout = 24v. Done in voltage mode for obvious reasons. (Split cap balancing etc) Cant we just find the output LC resonant frequency....(which is also the frequency of the troublesome output double poles). So then all we do is find the Output...

www.edaboard.com

It always used to be said that a dc blocking cap was needed
when in voltage mode. Then the voltage build up on the blocker will oppose the
off balancing factor. But be sure your cap blocker is not too big. You need it
to show some voltage change during the cycle on time.
Anyway, current mode with slope compensation also can be workable with
half bridge.
Also, some people do extra circuits to detect the imbalance, and then reduce
one of the gate drives minutely, so as to even things back up again...but generally
, nobody bothers with that and just does a 2 tran forward instead.

By the way, i'm doing CC CV for 72v 200a gel battery bank. i need around 200w constant. is two switch forward good enough for my project or better to go for full bridge? Regards

 

[KlausST]

Hi,

What´s the use of post#3?

By the way, i'm doing CC CV for 72v 200a gel battery bank.

you mean:
72v --> 72V (nominal battery voltage)
200a --> 200Ah (nominal battery electric charge)
???

"A" and "Ah" are totally different things.
You need to clarify.

Why don´t you call it "charger"? ... when it is meant to charge batteries?

i need around 200w constant

Are you sure you want to design a 200W constant power charger? ... before you said CC, CV.
Please clarify.

****
CC ... without saying what´s tha CC range
CV ... without saying what´s the CV range

Why do you hide important information like a secret. It just makes helping more difficult, lengthy and inaccurate.

****
Sorry for being honest: But this PCB layout does in no way follow general PCB standards and for sure not the special standards a switch mode power supply / charger needs.
It seems you do not have much experience in designing PCBs. A switch mode power application is rather difficult, because one has to handle:
* high currents --> requiring wide traces ... or power planes or copper fill
* rather high voltage / isolation
* high dV/dt signals -- requiring small conductive area (to keep capacitance as well as EMI low)
* high dI/dt signals --> requiring low impedance loops, and "small enclosed area" loops to keep EMI low

I don´t expect it to work reliably (long term. Slowly killing semiconductors by stray inductance spikes) and legally (EMI) without a proper and absolute solid GND plane.
A GND plane indeed would for me the very "start" of doing such a PCB layout.


Klaus

 

[gb_R]

Hi,

What´s the use of post#3?


you mean:
72v --> 72V (nominal battery voltage)
200a --> 200Ah (nominal battery electric charge)
???

"A" and "Ah" are totally different things.
You need to clarify.

Why don´t you call it "charger"? ... when it is meant to charge batteries?


Are you sure you want to design a 200W constant power charger? ... before you said CC, CV.
Please clarify.

****
CC ... without saying what´s tha CC range
CV ... without saying what´s the CV range

Why do you hide important information like a secret. It just makes helping more difficult, lengthy and inaccurate.

****
Sorry for being honest: But this PCB layout does in no way follow general PCB standards and for sure not the special standards a switch mode power supply / charger needs.
It seems you do not have much experience in designing PCBs. A switch mode power application is rather difficult, because one has to handle:
* high currents --> requiring wide traces ... or power planes or copper fill
* rather high voltage / isolation
* high dV/dt signals -- requiring small conductive area (to keep capacitance as well as EMI low)
* high dI/dt signals --> requiring low impedance loops, and "small enclosed area" loops to keep EMI low

I don´t expect it to work reliably (long term. Slowly killing semiconductors by stray inductance spikes) and legally (EMI) without a proper and absolute solid GND plane.
A GND plane indeed would for me the very "start" of doing such a PCB layout.


Klaus

English is not my first language use your common sense rather going too deep on the language mistakes. i know this is not a english class forum. . people who have common sense and knowledge about half bridge converter already understood my question and gave me the right suggestions. you can just walk on if you don't understand what i'm writing. Thanks

 

[gb_R]

For now i want to make sure, the IGBTs must be equally far from the GDT or that 3cm differences shouldn't make any problem unless otherwise ? here is the pcb layout. i will upload other information soon. Regards

I'm trying to make a half bridge power supply . after a year of learning, now every thing looks perfect when i run it at 45V DC bench power supply but when i run it on mains (240AC) the low side IGBT get hotter then the high side one ( I don't have a temp meter at the moment but it looks x2 times hotter then high side one when i touch the heatsink ). I swap the IGBT and the other components low side to high side but the issue always stays on the low side. GDT voltage and signals are same on both side. only the difference is the low side IGBT to GDT tracks are about 3cm longer then the high side one. could that be the reason ? ( every thing looks perfect when i run it at 45V DC bench power supply, both IGBT equally warm ). Regards

AS I NOTICED THIS FORUM IS USELESS BECAUSE OF LOTS OF NONSENC PEOPLE MERE, I TRIED TO DELET MY POST AND DEACTIVE MY ACCOUNT BUT COULDN'T FIND THE OPTION. ADMIN,PLEASE DEACTIVE MY ACCOUNT. THANKS

 

[BradtheRad]

See:

edaboard.com/threads/requests-to-deactivate-delete-edaboard-user-account.318279/page-8

 

[gb_R]

See:

edaboard.com/threads/requests-to-deactivate-delete-edaboard-user-account.318279/page-8

Hello, i would like to delete my post before deactivate. Thanks

 

[FvM]

Posts violating forum rules will be deleted, but there's no reason to delete this thread or specific posts.