Electronics > Projects, Designs, and Technical Stuff
Could you review regulator stage of bench PSU design
virinom:
Hi all,
I am designing 0-50V 0-10A CV, CC digital bench power supply. By saying digital I am referring to controlling output transistors with DAC from MCU and setting DAC voltage by reading output values with MCU using ADC.
I started with power stage. In Multisim simulation, I used a potentiometer instead of DAC and I don't have ADC stage. I'm planning to use MJ15003 in circuit but I used MJ15024G for simulation. Could you please look at my power stage and inform me If there is any major design error or If you have any recommendation.
I am putting Multisim link below, you can also find schemetic in attachments.
https://www.multisim.com/content/wRrPWn9FGKN44TeTAtQD3h/power-supply/
Thank you
kallek:
Hi, and welcome!
You need analog feedback from output. Digital feedback is too slow. I also suggest to start with lower voltage and current. Designing that kind of linear power supply is big challenge to everyone.
Doctorandus_P:
50V 10A is pretty ambitious.
A lineair supply would need to be able to dissipate 500W in worse case condition.
That is like a big CPU cooler for each of your 4 power transistors.
Do you have a good reason for this power requirement?
In my experience, I can do most projects with 30V 500mA power supply, and when more power is needed it often does not have to be well regulated.
You are also likely to want to have multiple power supplies. So even if you first design / build a small one, then you will still use it after you built the big monster.
I also agree with kallek. Use a uC and dac to make a setpoint, and use analog circuitry to regulate the output voltage.
dietert1:
There is analog feedback. The U1 gain stage has G = 6, so at 2 V input it outputs 12 V. The Q3/Q2 gain stage has G = 17, so that gives 204 V instead of 50 V. And something is wrong with R7.
Regards, Dieter
wraper:
--- Quote from: dietert1 on August 28, 2020, 10:14:37 pm ---There is analog feedback. The U1 gain stage has G = 6, so at 2 V input it outputs 12 V. The Q3/Q2 gain stage has G = 17, so that gives 204 V instead of 50 V. And something is wrong with R7.
Regards, Dieter
--- End quote ---
It is not a feedback he talks about. Digital feedback is not impossible as such. However not with a regular MCU, nor it would be trivial. Very complicated stuff to implement. Here is simplified linear PSU where you can see the feedback.
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