I'm currently working on a PhD about a DC-DC multiphase 3 level flying capacitor converter. It's always refreshing to see a clear and detailed presentation, it helps not to lose sight of the main goals whenever I'm making a big deal of small but tedious technicalities. In fact, I checked you channel and saw (by the titles) many videos that might help me in my investigations. I'll be sure to watch them. Thank you for your work, professor.
Congratulations on an excellent series of lectures. Another advantage of multiphase converter presumably is that the power dissipation will be shared between output transistors. So in high reliability/safety critical applications the semiconductor junction temperature rise (above the heat sink temperature) of each transistor will be reduced. Lower semiconductor temperature rise increases reliability (Arrhenius law).
This is another great video. I know this is a very old video but I would like to see how the number of stages affects the control loop and how to deal with compensation in designs that do phase shading. You have taught me so much thank you for your time.
Mr. professor, I can not figure out, why I have different currents in my 2-phase BUCK MPPT, at 20 kHz, currents are 7:5 AMPS, at 25 kHz curents are 17:17, but if I go higher 23:21 AMPS, so I need to change freg. for IR2104 to 28 kHz, than 22:22 AMPS is OK, but at 27:23 AMPS and 28 kHz I have again uneven currents. Where is the problem ? ESP32 to IR2104 connections ? IR2104 - resistors + diodes - IRFP4110/4227 FETs ? Connection FETs to 45 AMPS / 3.9 mOhms toroids ? Can problems arise from not properly designed snubbers atr FETs ? Is problem Trr and Qrr of the FETs ? Or problem is deadtime of IR2104 ? Or problem is low drive current at gates from IR2104 ? I need to know, what is with high probability the cause of the problem.
Hi Professor, Under low loads, we are doing diode emulation(DCM) to reduce conduction losses due to reverse current. However, isn't the diode more lossy than FET in terms of conduction losses?
Thank you so much for the great presentation. Do you think lossless current sensing is practical considering tolerance of inductors, resistors and capacitors? Thanks
Professor Sam, do you have any other video where you go into more details on the bandwidth of the control mentioned at 18:26 ? I didn't understand this concept.
Sam, have you written hard copy/print books on power electronics?? I respect your material sir and would love to read your book on this subject. RU-vid is great but printed text is easier on the eyes for long hours. My opinion
@@sambenyaakov no problem. Even printed lecture notes could suffice. Slides that could be printed would work as well. Just I love how you analyze this topic from multiple angles. It's refreshing to see someone elaborate on power electronics discussing not just power stage but also multiphase converters and closed loop compensation, and practical topics such as EMC, PCB of power supplies etc.
Dear Professor Yaakov Great and informative video as usual. How does one generate phase shifted pwm's ? And is there a risk of shoot through, if top gate of phase B is on at the same time as bottom gate of phase A ?
At 14:10 you say that load sharing leads to a higher switching frequency, beacause we have less switching losses. Why is that the case? If we share the current between many inductors we can make the switches smaller, but we also have more switches to turn on. Shouldn't the switching loss stay the same?
Hi, you got a point there. What I had in mind when saying this was the practical ability to work in borderline mode and the fact that many transistors have better thermal conduction so you can allow higher dissipation.
Hi professor, recently multiphase buck converter using coupled inductor get many attention by claiming to have large inductance in steady state while small inductance during transient and therefore achieved small current ripple and fast transient, can you make a video to give a brief overview of it?
Also, you have to think about your mechanical structure. You will have one busbar collecting the output current on all buck phases. Some of those bucks will be closer to the load, some further, so the phases will have slightly different impedance between them and the load. Your cooling system can also be an issue : if you don't balance your cooling system (for example, you put a fan in front of your phases, but some of them are a bit far away from the airflow), then some phases will heat more than others for the same current passing through. Since higher temperature often means higher RdsON, it will lead to lower currents in those undercooled phases, and so higher currents in the other phases. In the end, this phenomenon tends to balance itself naturally (as you can logically guess), but putting some thoughts into your cooling system may help reduce the overall conduction losses, minimize fault risks, etc.
Thanks for the video, im gonna look at it in more detail, but i wanna ask a question, what would you suggest if i wanna use that topology for high voltage conversion lets say converting 160 VDC to 28vdc @300a? İ couldnt find a suitable controller.. :(
Mirror current sensing has an issue. It will not follow the current ramp in main MOSFET, which is dictated by inductor in series to main MOSFET. But mirror MOSFET has a resistor which means no ramp and flat current once the MOSFET turns on completely.
Thank you so much ! I have learned a lot from you sir . I had a question though, I have seen some multiphase dc-dc systems where they use multiple converter ICs controlling their individual phases but are connected through a clock synchronization input pins. Why it is used ? And how does it help ? Thanks in advance
Do you have experience with a multiphase buck with coupled inductors? It would be interesting to learn about the performance as compared to the non coupled case.