An Easy Explanation of Subharmonic Oscillations & Slope Compensation in Current Mode Power Supplies
HTML-код
- Опубликовано: 1 окт 2024
- In this video, Dr Seyed Ali Shirsavar from Biricha Digital explains what subharmonic oscillations are, why they happen and how we fix the problem using slope compensation.
As always, we have tried to keep all the explanations, clear, concise and easy understand.
You can download a more detailed presentation from here:
www.biricha.co...
Excellent top notch quality training sir! Thank you for sharing this with us. It's like going to MIT....for FREE!
Excellent presentation! Excellent explanation!
Thank you for the video! Your explanation was great.
Another great video. Thank you for all the effort and sharing 🙏🙏🙏Waiting for the next episode 👍
I appreciate the effort that goes into videos like this, and also the desire to tell the story clearly. I'm an EE, I know a bit about switching power supply circuits. and unfortunately I don't think this video achieves its goals. The main problem is that the explanation is unmoored from even a generic diagram of the circuit to which it pertains. The presenter identifies all the signals under discussion just verbally and rather vaguely, so it's often hard to tell what is actually being discussed.
For example, around 3:30 Iref is referred to as "our demand current value". Wat does that mean? This is surely a power supply producing an output voltage, (that's the demanded value), in which there's feedback that the controller uses to set the peak current of the ramp for the next cycle. I guess Iref is that peak value? But that value will change from cycle to cycle, so why is it referred to as "Iref" as though it's a fixed reference current? Either I'm unfamiliar with the terminology or I completely don't understand the circuit under examination.
Later there's a comment that the subharmonic oscillation will greatly increase ripple current. Well I suppose that's just describing the alternating short and long current ramps. But what is the significance -- is the concern about disrupting the upstream supply? Or disturbing the downstream circuity, where I would have thought that voltage ripple would be a more immediate concern? Here again, being able to point to the location in the circuit that the issue applies to would be very helpful.
I was very impressed with the nice animated graphs at 10:39 ... except I didn't understand what they display. What are the axes, and what are the signals plotted in red blue and green, referred to points in a schematic that I could recognize?
At the point where discussion moved on to some kind of synthetic slope I was basically lost. I thought the sloped signal was the inductor current ramp, something tangible. So I didn't see how that could somehow be made synthetic. Maybe this is trying to illustrate the signals that the controller pays attention to, and the enhancement is to revise this controller input variable by adding in an additional signal or calculation. I'm not at all sure from the verbal discussion, but would have been if the graphed variables were identified with points in a schematic. (Possibly with the schematic enhanced to show stages of the controller's internal algorithm, if that's the story.)
So again, I appreciate the effort, but for me, who I think might be a representative target audience, this flew over, or at least around, my head! A schematic or two to identify signals please!
Just to add --- I did see that there's a PDF with more detailed notes. I will download and read that. So no need to answer the questions I raised per se. This is more a suggestion about ways to make future videos more followable.