PRECIsion Power SUpply project
PreciPSU is an attempt to build high performance power supply. The idea started few years ago but it was never realised. Some major target performance specs are as follows:
- three isolated channels
- around 50W per channel
- 24V/3A output per channel
- lowest possible ripple at fastest response
- small size
- programmable via USB
- nice housing with minimalist user interface (2 plugs per channel, knob, button and small display
Update 15.7.2017: block diagram
PreciPSU Block diagram
The progress of the project will be listed here. When project will reach final stage, the content of the page will be rewritten for DIY-ers and with proper documentation. Just keep following…
Update 22.7.2017: Final analog stage
Schematic (PDF): precipower-postreg-sch
This block has in general two important inputs and two outputs: Vset, Iset and Vget, Iget (respectively).
The operation is based around LT rough linear adjustable regulator LT3081. Prototyping circuit was built to test functionality and performance, mostly the response time. This first prototype has response time 6ms from 0 to 99% when control voltage Vset was steped from 0V to 24V output. It’s quite good result (compared to high performance PSUs which have such transient response in range of 100ms).
Here is our first prototype of the final stage:
Final linear stage prototype
Update 24.7.2017: Tracking DC/DC source
Next essential stage is tracking DC/DC source. It is based on TI’s TPS54540
Here is schematic: precipower-trackingdcdc-sch
The prototype was assembled and some preliminary testing has shown proper operation. Unfortunately, the capacitors on stock were not optimal as well the main inductor. The result was some combs in the output signal. Proper components will solve this in final design.
Here is first prototype of the tracking switcher:
Tracking DC/DC supply – first prototype
The output voltage is about 3V above tracking voltage input. The step response time is in the range of 10ms, which is similar to output stage. Testing was performed with 0V to 27V with thick film 15 ohm load submerged in the glass of water.
Testing tracking DCDC with load
Hello.
It’s a really promising project. I always wanted to create a precision power supply with multiple SMPS stages. Unfortunately I’m somewhat inexperienced with magnetics, so my AC/DC converter (full bridge, resonant) designs failed and I remained with only Matlab simulations. So here I am reading this post and bookmarking it.
With regards,
Fehér Áron.
Dear Áron, thank you for your visit. I will keep the page updated with the progress.
I also working on a precision lab supply and made a few progress and some mistakes. You should consider the following:
The LT3081 current limit/setting are not precise, take a look on the diagrams in the datasheet. So your current adjustment are just a thumb value.
The output capacity of your analogue stage is almost 100µF which is quiet high for a lab supply. Good supplies have less then 10µF. The output capacity is important if your load produces a short circuit or just be switched on and your supply have to change from constant voltage to constant current mode. If your unregulated output capacity is to high, it can destroy your connected device.
Best
Dear bimbo385, thank you for useful suggestions.