Digitally controlled power supply response time

[diyaudio]

Putting MCU in control loop generally is a very stupid thing to do. Not only you will get a huge delay but also very bad (unexpected) regulation.

You probably never came to understand the role a DSC Digital Signal Controller plays other than Motor Control applications.

There are tons of examples and companies that uses a "digital" control loop in SMPS designs, theses digital control loops sit in the heart of the controller (and not as secondary control that imposes the analogue loop) ,digital control loops is this the way forward for many "obvious reasons" its the future weather you agree or not.




 

[David Hess]

There are tons of examples and companies that uses "digital" control loop logarithms in SMPS designs, theses digital control loops sit in the heart of the controllers (not as secondary control that imposes some analogue loop) ,digital control loops is this the way forward for many "obvious reasons" its the future weather you agree or not.

Control loop logarithms?  Weather?

What are some of the many obvious reasons?

[wraper]

Putting MCU in control loop generally is a very stupid thing to do. Not only you will get a huge delay but also very bad (unexpected) regulation.

You probably never came to understand the role a DSC Digital Signal Controller plays other than Motor Control applications.

There are tons of examples and companies that uses "digital" control loop logarithms in SMPS designs, theses digital control loops sit in the heart of the controllers (not as secondary control that imposes some analogue loop) ,digital control loops is this the way forward for many "obvious reasons" its the future weather you agree or not.

Question was about lab power supply without any mention of SMPS. Answer stated: GENERALLY, not always

[diyaudio]

There are tons of examples and companies that uses "digital" control loop logarithms in SMPS designs, theses digital control loops sit in the heart of the controllers (not as secondary control that imposes some analogue loop) ,digital control loops is this the way forward for many "obvious reasons" its the future weather you agree or not.

Control loop logarithms?  Weather?

What are some of the many obvious reasons?

typo whether.

"obvious reasons" are.

* Flexibly power control algorithms are upgradable as firmware.
* Control algorithms are possible and are not dependant on passive components that control poles and zeros , also passives age with environmental conditions alters characteristics, firmware doesn't.
* Intelligent software control management.
* Lower design BOM and maintenance cost.
* Efficiency and performance.
* Intellectual property now resides on the chip as software so its harder for copy cats.

You don't have to believe me its already taken off.

The hard part is programming the system and the amount of work involved taking DSP theory into the power control world, Microchip has a good app note with source (written in assembly) on this subject that uses a DSC.

http://www.microchip.com/pagehandler/en-us/technology/intelligentpower/





 

[David Hess]

* Control algorithms are possible and are not dependant on passive components that control poles and zeros , also passives age with environmental conditions alters characteristics, firmware doesn't.

Unfortunately high ripple current input and output electrolytic capacitors are still going to age altering the control loop.  Maybe the controller will be able to adaptively compensate for this over time.  Fail-safe operation would be nice but I have not seen it as a significant problem in existing designs.

* Efficiency and performance.

I am not convinced that efficiency will be improved significantly but performance for a given power density could be.  I would hope reliability is improved simply because of better monitoring.

* Lower design BOM and maintenance cost.

Won't the maintenance cost be the same as it is now?  Throw it away and buy a new one?  It certainly will not be any more repairable.

* Flexibly power control algorithms are upgradable as firmware.* Intelligent software control management.
* Intellectual property now resides on the chip as software so its harder for copy cats.

I would add, "Easier and more effective hardware rights management."  This will become another rent extraction tool.  With some of the dumb design decisions I have seen recently, it could also be a security problem.

You don't have to believe me its already taken off.

I do not doubt these exist.  I doubt that it will be a universal replacement for existing controllers except in specific applications and I am dubious of the marketing claims being made.  Of course it is the greatest thing since, well, ever.

The hard part is programming the system and the amount of work involved taking DSP theory into the power control world, Microchip has a good app note with source (written in assembly) on this subject that uses a DSC.

I expect that the manufacturers pushing these solutions will work hard to reduce the needed design work to cookbook engineering level.

[NiHaoMike]

In PFC applications that often see part load, adding a little digital control can let the PFC operate with higher efficiency by gating off operation during the low parts of the wave where the efficiency is low, while still maintaining a minimum power factor.

[Rick Law]

This discussion is interesting and educational.

When I build the charger (which I referred to in my OP), I did it just to experiment with different cutoff voltage.  I was exposed to the issue with response time.  I concluded at that time the system response time (in 10-50 ms) is not important for the application I had in mind.

Recent thread about some cheap cc/cv led driver / charger bring that back into mind hence my OP about how other digital PSU's response time would be.

I think I will put it on my "TODO" - pull my "charger" back out from the "box of the forgotten" and reheat that thing (re-familiarize and generalize it a bit) to see what else I can learn...

Rick

[coppice]

If you think you have seen a software free implementation of a power supply control loop look closer. Chances are that under the skin its some form of processor.

Did you have a specific application in mind where they are ubiquitous because I run across non-digital but not necessarily non-sampled control loops all the time.

Sorry, I missed a word. I should have said...

If you think you have seen a software free implementation of a digital power supply control loop look closer. Chances are that under the skin its some form of processor.