There is also another benefit from active rectifiers or ideal diodes that can be useful in some cases. With a regular diode or rectifier there will be induced RFI noise from LCR type ringing when used with a regular transformer. This is due to the switch-on transient from the diode. In some cases the RFI can cause issues with sensitive circuits. The RFI can be dampened with snubber networks, usually a series capacitor and resistor in parallel with the transformer. An active rectifier eliminates this problem, because it begins conducting almost from 0 V. Personally, I've used LT4320 with four Mosfets.
This is the very first time I have seen a situation where high temps of device is beneficial as here , resistance decreases and thus increase in efficiency... This is a quite good lesson that we must not take anything for granted in
Thank you for another very interesting video, I am just now designing a power supply with and active rectifier and It helps me a lot to see diferent estrategies and examples for better understanding of all issues and benefits. looking fordward for the second part!!
Another application of active rectifiers are in flyback convertors as it not only increases efficiency but also allows to get several stable voltages from single convertor. Traditionally if there are windings for +12, +5 and +3,3 volts for example, one should choose just one voltage for feedback and that one would be most stable. Another voltages would increase a lot under low load because of lower voltage drop at diode and some high-voltage spikes at transient which charge output capacitors. But when there is active rectifier which stays on all the time of flyback, these problems go away. Stabilizing one voltage basically means stabilizing them all!
I guess I did not look at current since there is not much of a difference as long as the same output capacitor is used. The big differences occur in voltage. Part 2 in work :D
Clear and well done!👍I see this rectifier used more frequently now and 4 years ago, I got a Pace ADS200 soldering station and has it too. I managed to convince Pace to send one to Dave Jones for review (today, his JBC gathers dust..)
I guess the main reason why you see more active rectifiers today is because the price of very low Rdson transistors has gone down. In the past it would cost a fortune to make a
great subject , I use this LT4320HMSE#PBF in my amplifier with N channel Mosfet IPB017N08N5, usually active rectifier use both P and N channel. which is in my opinion not good , this circuit has even pump up charger too ,and you need only N channel .
Don’t you need a boost to turn on the high side FET on a full bridge sync rectifier? How do you power those comparators and have them output higher voltage than high side?
Hello John, as long as the high side is P-channel then you don't need any higher voltages; its true however that Nchan is cheaper, so if you want to use that, then a boost or some other circuit is needed.
Good one. So the n channel mosfet has to be used with the drain at lower voltage than the source... To avoid the internal diode providing a reverse path from the output capacitor!?
Great video as always, looking forward to the second part! :) You mentioned forward-voltage drop trade-offs between silicon and Schottky diodes, but what about switching speed (reverse recovery time) which also contributes to losses in high frequency converters? Also, why was ".options cshunt=1e-14" used on 14:37?
Great points! When talking about high frequency behavior, Trr (reverse recovery time) is typically a problem that is not associated with Schottky diodes, the issue there is only the large junction capacitance(Cj). At 50 or 60 Hz though, neither of these parameters should be of any concern with modern diodes though. For whatever reason the simulation was having convergence issues with the op-amp model, and usually an easy fix is the addition of the cshunt (capacitance from each node to ground) option, 1e-14 being a mostly neglectable 0.01pF; even 1e-15 is usually enough
I have a question about active rectifiers. What happens with noise? Meaning if i know that i will use a rectifier with a very noisy input signal. Does active rectifiers need an attachment to filter noise?
How dare you insult the legendary FULL WAVE RECTIFIER!!!! @THE_RECTIFIER , na hjust kidding this is probably the mother of all all the mother of The FULL WaVE rectifier........
Its not just about high power; this sort of rectifier can be used in wireless power transfer - relatively small amounts are power are transferred, but efficiency is very important. Its also a topic of price, when is the extra price still worth it?
Or chain link rectifier between volt regulator stuff or how a director can be used to stop a curcit especially neg run curcit act as a filter cup or regulat DC signal on neg lines to stabilize it or on the relay flyback led set that stops the operation???? annoying no!.
use the motor as a flywheel, that will smooth the dc output, assumed that you have a dc output generator attached to the sudo-dc input, so diode full wave rectifier with the flywheel dc motor to dc generator link
so you dont have fans in your electronics systems, use the mechanical version you get the application alongside without much extra effort, ie mechanical fan generator power source
I have used a design with traditional bridge configuration, but with such a high current that the diodes eas screw mounted on a heatsink. So clearly a big loss. An othe way to rectify very high current (and/or voltage) in the hundred of mega watt range is using mechanical switching. Or electric generator / motor configurations.
There is also another benefit from active rectifiers or ideal diodes that can be useful in some cases. With a regular diode or rectifier there will be induced RFI noise from LCR type ringing when used with a regular transformer. This is due to the switch-on transient from the diode. In some cases the RFI can cause issues with sensitive circuits. The RFI can be dampened with snubber networks, usually a series capacitor and resistor in parallel with the transformer. An active rectifier eliminates this problem, because it begins conducting almost from 0 V. Personally, I've used LT4320 with four Mosfets.
This is the very first time I have seen a situation where high temps of device is beneficial as here , resistance decreases and thus increase in efficiency... This is a quite good lesson that we must not take anything for granted in
In higher power designs, totem pole PFC or Vienna filter architectures are widely used. Also solves the problem of power factor and THD.
So Googling Vienna filter architecture got enough good papers from TI, On-semi and Research Gate for me to understand.. Thanks!
Great talk coach. Well I mean... I appreciate your time making these workshops.
As always, it a pleasure watching.
God Bless.
Thank you for another very interesting video, I am just now designing a power supply with and active rectifier and It helps me a lot to see diferent estrategies and examples for better understanding of all issues and benefits. looking fordward for the second part!!
Very good proffesional talk
Another application of active rectifiers are in flyback convertors as it not only increases efficiency but also allows to get several stable voltages from single convertor. Traditionally if there are windings for +12, +5 and +3,3 volts for example, one should choose just one voltage for feedback and that one would be most stable. Another voltages would increase a lot under low load because of lower voltage drop at diode and some high-voltage spikes at transient which charge output capacitors. But when there is active rectifier which stays on all the time of flyback, these problems go away. Stabilizing one voltage basically means stabilizing them all!
Thanks for this brilliant tip!
I wouldn't have thought of that.
I enjoyed this video and liked the opamp gate driver.
This is a great video but I'd love to also have the current comparison as well as the voltage comparison in the end. I can't wait for part two.
I guess I did not look at current since there is not much of a difference as long as the same output capacitor is used. The big differences occur in voltage. Part 2 in work :D
Thank you. I have spent a lot of time to find information about active rectifiers. This video is great
Clear and well done!👍I see this rectifier used more frequently now and 4 years ago, I got a Pace ADS200 soldering station and has it too. I managed to convince Pace to send one to Dave Jones for review (today, his JBC gathers dust..)
I guess the main reason why you see more active rectifiers today is because the price of very low Rdson transistors has gone down. In the past it would cost a fortune to make a
Mosfets always save the day
Would be interested to see how this relates to bidirectional PSU (like Meanwell BIC-2200 series or EV chargers's vehicle to grid/load tech).
great subject , I use this LT4320HMSE#PBF in my amplifier with N channel Mosfet IPB017N08N5, usually active rectifier use both P and N channel. which is in my opinion not good , this circuit has even pump up charger too ,and you need only N channel .
First 30 sec already made me chuckle
Pure excellent.
🙏
Such a good video!
Amazing video and great explanations. Is there any way we can download the simulation files you used in the video?
Don’t you need a boost to turn on the high side FET on a full bridge sync rectifier? How do you power those comparators and have them output higher voltage than high side?
Hello John, as long as the high side is P-channel then you don't need any higher voltages; its true however that Nchan is cheaper, so if you want to use that, then a boost or some other circuit is needed.
Good one. So the n channel mosfet has to be used with the drain at lower voltage than the source... To avoid the internal diode providing a reverse path from the output capacitor!?
Great video as always, looking forward to the second part! :) You mentioned forward-voltage drop trade-offs between silicon and Schottky diodes, but what about switching speed (reverse recovery time) which also contributes to losses in high frequency converters? Also, why was ".options cshunt=1e-14" used on 14:37?
Great points! When talking about high frequency behavior, Trr (reverse recovery time) is typically a problem that is not associated with Schottky diodes, the issue there is only the large junction capacitance(Cj). At 50 or 60 Hz though, neither of these parameters should be of any concern with modern diodes though. For whatever reason the simulation was having convergence issues with the op-amp model, and usually an easy fix is the addition of the cshunt (capacitance from each node to ground) option, 1e-14 being a mostly neglectable 0.01pF; even 1e-15 is usually enough
I have a question about active rectifiers. What happens with noise? Meaning if i know that i will use a rectifier with a very noisy input signal. Does active rectifiers need an attachment to filter noise?
👍👍👍
Would adding MLCC capacitors to each diode of Full Bridge Rectifier improve performance of the it ?
FULL BRIDGE ACTIVE-RECTIFIER
Good topic!
Thanks a lot.
For a 14v 70a dc power supply, what would be the ideal circuit with this level of amperage?
The issue of RFI and heat is important in my situation...
I liked the video but one question arises. How much power does the additional circuitry use?
How dare you insult the legendary FULL WAVE RECTIFIER!!!! @THE_RECTIFIER , na hjust kidding this is probably the mother of all all the mother of The FULL WaVE rectifier........
From what power would active rectifiers be worth it ?
Also i tried to find an integrated solution but i failed, might be because of chip shortage.
Its not just about high power; this sort of rectifier can be used in wireless power transfer - relatively small amounts are power are transferred, but efficiency is very important. Its also a topic of price, when is the extra price still worth it?
@@FesZElectronics thx i think i get it better now
Or chain link rectifier between volt regulator stuff or how a director can be used to stop a curcit especially neg run curcit act as a filter cup or regulat DC signal on neg lines to stabilize it or on the relay flyback led set that stops the operation???? annoying no!.
use dc-motor-to-ac style active mechanical generator, but in ac-to-dc-to-dc motor generator form
you can do all digital solid state in the mechanical equivalent simple form
use the motor as a flywheel, that will smooth the dc output, assumed that you have a dc output generator attached to the sudo-dc input, so diode full wave rectifier with the flywheel dc motor to dc generator link
so you dont have fans in your electronics systems, use the mechanical version you get the application alongside without much extra effort, ie mechanical fan generator power source
u are entire university bro
Nice shirt
I have used a design with traditional bridge configuration, but with such a high current that the diodes eas screw mounted on a heatsink. So clearly a big loss.
An othe way to rectify very high current (and/or voltage) in the hundred of mega watt range is using mechanical switching. Or electric generator / motor configurations.
Honda Activa
Rectified coyal
You ought to update the thumbnail-image to account for that glorious facial hair :)
;-)
Informative!