Hello Frex,
This is a great project! - You have done some really excellent work to get to near completion. I would enjoy building this PSU. Please keep us informed as to how you are getting along with it.
However, I am a bit concerned about the transformer - I'm not too keen on the idea of winding it myself (Safety etc.). Would it not be possible to specify an off-the-shelf part to help the likes of myself?
Ken
This is a great project! - You have done some really excellent work to get to near completion. I would enjoy building this PSU. Please keep us informed as to how you are getting along with it.
However, I am a bit concerned about the transformer - I'm not too keen on the idea of winding it myself (Safety etc.). Would it not be possible to specify an off-the-shelf part to help the likes of myself?
Ken
Hello all,
Some news of the EPSUX3 laboratory power supply project.
First, it was hard for me to devote my time on the project.
As i had already say, the project is 95% working, but it's
not sufficient IMHO.
After lot of tests and modifications, i decide to stop
the design of EPSUX3v1 project.
---
For information, the main issue of the PSU is it's inability to work in current mode when output voltage become low (<1V).
This "malfunction" is inherent on switching output converters.
Step down converter (buck) control the duty-cycle to change output voltage (and/or current, depending on how you control the feedback loop).
So, for very low voltage the PWM pulse width required become very low
and the controler is unable to produce it ! (It's because pulse width can't be indefinitely low !).In this mode, the controler continue to work
but apparent PWM frequency decrease because short pulse disappear !
The consequence is that the feedback control loop become unstable...
---
About 4 month ago, i finally decided to start a new version of this project : EPSUX3V2 !
Near to 75% of all electronics functions were already designed and tested ,
where almost all has been re-designed.
The objective is to stay in same enclosure (low weight and volume),
with very clean voltage and current mode régulation, more output power, easiest to build
for noob DIYers, higher overall efficiency and of course state of the arts
electronics design with all done to comply with EMC and safety requirements.
That a big job, but that progress fine !
The main design modifications from V1 to V2 are :
- EMI & safety design consideration
- Input Power factor corrector (PFC) with wide main input (85-265V 50/60Hz).
- Triple outputs, high efficiency, low EMI, 200W LLC converter (instead of ZVS flyback).
- Dual stage switching-linear regulators (with low Cout and fast transient response and low noise).
- More total power : 2 outputs from 0..20V 3A + 1 output from 0..10V 3A
Many functionnality of V1 are extended like :
- Lightweight small aluminium enclosure
- 3 x 7 segments green leds display with voltage/current setting for all outputs
- 3 iluminated digital encoders for U/I setting control.
- No MCU, all digital control use CPLD
- All outputs isolated from each other.
I've already build some prototype for all new features, except the PFC that is in progress. I plan to validate all functionality before the end of year.
For simpler information acces and no confusing with the first one, i will open very soon a new thread here for this new version. You will find more detailled informations, , description of the new architecture, full synoptic and pictures
of prototypes boards.
After a complete construction and full test review, the final objective
will be allow all DIYers to build and organizing a PCB group buy.
Thank you to all DiYers that follow the first thread, i hope they will enjoy
the project new life !
To soon.
Regards.
Frex
Some news of the EPSUX3 laboratory power supply project.
First, it was hard for me to devote my time on the project.
As i had already say, the project is 95% working, but it's
not sufficient IMHO.
After lot of tests and modifications, i decide to stop
the design of EPSUX3v1 project.
---
For information, the main issue of the PSU is it's inability to work in current mode when output voltage become low (<1V).
This "malfunction" is inherent on switching output converters.
Step down converter (buck) control the duty-cycle to change output voltage (and/or current, depending on how you control the feedback loop).
So, for very low voltage the PWM pulse width required become very low
and the controler is unable to produce it ! (It's because pulse width can't be indefinitely low !).In this mode, the controler continue to work
but apparent PWM frequency decrease because short pulse disappear !
The consequence is that the feedback control loop become unstable...
---
About 4 month ago, i finally decided to start a new version of this project : EPSUX3V2 !
Near to 75% of all electronics functions were already designed and tested ,
where almost all has been re-designed.
The objective is to stay in same enclosure (low weight and volume),
with very clean voltage and current mode régulation, more output power, easiest to build
for noob DIYers, higher overall efficiency and of course state of the arts
electronics design with all done to comply with EMC and safety requirements.
That a big job, but that progress fine !
The main design modifications from V1 to V2 are :
- EMI & safety design consideration
- Input Power factor corrector (PFC) with wide main input (85-265V 50/60Hz).
- Triple outputs, high efficiency, low EMI, 200W LLC converter (instead of ZVS flyback).
- Dual stage switching-linear regulators (with low Cout and fast transient response and low noise).
- More total power : 2 outputs from 0..20V 3A + 1 output from 0..10V 3A
Many functionnality of V1 are extended like :
- Lightweight small aluminium enclosure
- 3 x 7 segments green leds display with voltage/current setting for all outputs
- 3 iluminated digital encoders for U/I setting control.
- No MCU, all digital control use CPLD
- All outputs isolated from each other.
I've already build some prototype for all new features, except the PFC that is in progress. I plan to validate all functionality before the end of year.
For simpler information acces and no confusing with the first one, i will open very soon a new thread here for this new version. You will find more detailled informations, , description of the new architecture, full synoptic and pictures
of prototypes boards.
After a complete construction and full test review, the final objective
will be allow all DIYers to build and organizing a PCB group buy.
Thank you to all DiYers that follow the first thread, i hope they will enjoy
the project new life !
To soon.
Regards.
Frex
Hello prasimix,
The output regulator is the LT3081, so ripple is very low despite use of switched pre-regulator. I don't have made serious ripple measurement on my prototype board yet, but i will post some scope records when this was done.
About channel crasstalk, because the interchannel insulation is high, i don't think that
will be visible.Same as previous, i post as soon it's done.
I just have opened the new thread for the V2 PSU, it's HERE.
Regards.
Frex
The output regulator is the LT3081, so ripple is very low despite use of switched pre-regulator. I don't have made serious ripple measurement on my prototype board yet, but i will post some scope records when this was done.
About channel crasstalk, because the interchannel insulation is high, i don't think that
will be visible.Same as previous, i post as soon it's done.
I just have opened the new thread for the V2 PSU, it's HERE.
Regards.
Frex
Hello,
The LT3081 has been added for that but not only.
Voltage and current regulation has now made by the LT3081 not
by the switching step down TPS5450 (regulate low voltage with TPS5450 cause issue).
In order to avoid the linear regulator to dissipate too much power,
the feedback loop coming to the TPS5450 is the differential voltage
between input and output of the LT3081.
Adding the LT3081 allow high rejection of pre-converter switching noise
and improve transient load regulation.
Frex
The LT3081 has been added for that but not only.
Voltage and current regulation has now made by the LT3081 not
by the switching step down TPS5450 (regulate low voltage with TPS5450 cause issue).
In order to avoid the linear regulator to dissipate too much power,
the feedback loop coming to the TPS5450 is the differential voltage
between input and output of the LT3081.
Adding the LT3081 allow high rejection of pre-converter switching noise
and improve transient load regulation.
Frex
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