I haven't seen a person ever explaining complex things so easily and neatly. I really admire your knowledge.

@sambenyaakov

4 жыл бұрын

Thanks Satyajit

I've learned so much from you in just the last couple of days. I really appreciate your videos.

@sambenyaakov

4 жыл бұрын

👍😊

Been many years since I was in school but this was a good refresher. Thanks for a good presentation. And thanks to those below who commented on some of the details.

@sambenyaakov

4 жыл бұрын

Thanks

Thank you very much, sir, for the info you have provided! Very awesome teaching, would certainly recommand to others.

Thank you very much Prof. Yaakov your active current sensing technic will help me to make a cheap measuring device on the oscilloscope !

@sambenyaakov

3 жыл бұрын

Thanks for note. Happy to hear that.

Very interesting. Your intuitive teaching style is helping me understand dc converters much better. I'm still challenged by a lack of underlying math skills, but your helping me push my practical understanding. That's a tremendous talent for someone to communicate a subject like this without physical demonstration in a lab. Thanks.

@sambenyaakov

7 жыл бұрын

Thanks for comment.

This gentleman has certainly succeeded in illustrating and showing the beauty and the elegance in this area of engineering through how he relates current sensing to voltages in so many diverse manners. I appreciated all of them, but the manner in which he oriented "Vectors" to make a current passing through a path, reflect itself as a voltage," somewhere else" in the circuit, is the brilliant combination to get unity in the numerator divided by the denominator in the phase-shifting networks shown at 17:54. Sir, I tip my hat to you, my congratulations. As an old engineer, I must say that seeing this video has ended the year 2020 with great admiration of this gentleman. Thank you.

@sambenyaakov

3 жыл бұрын

Thanks Carmel for sharing the mental excitements and exuberance when uncovering the beauty of electronic engineering.

Very informative! I like your videos because they show how to use the formulas, they have a mathematical approach.

@sambenyaakov

3 жыл бұрын

Thanks for note

your videos are more than phenomenal Dr. Sam.

@sambenyaakov

7 жыл бұрын

Thanks. Comments like yours keep me going.

Dr Sam, it is really cleared lot of my doubts that's so kind of you.

@sambenyaakov

3 жыл бұрын

👍😊

Thank you for your explanations. I'm learning so much from you.

@sambenyaakov

4 жыл бұрын

Thanks for comment

Amazingly clear explanation! Thank you!

@sambenyaakov

6 жыл бұрын

Thanks

You so good at what you do Prof that even the trolls can't touch the dislike button. I've hardly seen that happen before on youtube. Awesome. I subscribed.

@sambenyaakov

6 жыл бұрын

Hi Emanuel, Thanks for comment.

Excellent. Especially in the final approach. Thank you.

@sambenyaakov

5 жыл бұрын

😊

I'm an EE engineer with much experience and I can say your videos and explanations are awesome! Makes it fun to keep learning . Thank you.

@sambenyaakov

5 жыл бұрын

👍😊

@basaltnow

2 жыл бұрын

I totally agree, very good compilations of the must know and must do things to suceccfully have a dcdc running stable.

Thanks a lot for the very intersting explanation, always very sharp and clear.

@sambenyaakov

3 жыл бұрын

Thanks

Really very helpful, you are genius of power electronics. Not only this video but all of your videos are superb. Very good explanation 👍

@sambenyaakov

2 жыл бұрын

Thanks

Fantastic Explaination about real word things.... Thank you....

@sambenyaakov

4 жыл бұрын

Thanks

its nice and great videos Mr.Sam. Thank you so much for sharing info and its more useful

@sambenyaakov

4 жыл бұрын

Thanks

This is my first video of yours if seen and I loved it.. I'm going to subscribe straight away. 👍👍 brilliant

@sambenyaakov

4 жыл бұрын

Thanks

You explained the concepts well. Pls do more vids, it's really helpful.

@sambenyaakov

Жыл бұрын

Thanks. Will try.

Dear Prof. Sam, thank you for such a valuable education video in english! I made some conclusions after watching, but I'm not sure that they are correct. 1) As we need to reset core after we had pulse, we can use high enough Rr resistor. That givs us a big area under curve in a reset period, so we can reset core at wery short time. So that sensor could work close to 90% of Duty cycle. And Using HV diode i'll be safe. 2) As we should have a Rr - reset resistor the total current of the secondary will be IL*1/n=ILm+IR+IRr. So to ensure that the most part of the current is current through sensing resistor, we should have IRr and ILm as low as possible. In order to achive this, high value Rr will be nice too. 3) To ensure in low value of ILm and fulfillment of the condition: 2pi*fsw*Lm>R, i will use core material with highest "ue" possible. Thanks again for the great stuff!

@sambenyaakov

4 жыл бұрын

Vasiliy,. You are correct see minute 9 and on. Thanks.

I'm watching this video again because it is one of your best. It's a shame that there are only 22,404 views!

@sambenyaakov

5 жыл бұрын

Well, there aren't that many smart people in the world. Thank.

So nice you have made me informed may God reward you

@sambenyaakov

3 жыл бұрын

Thanks

Hello prof. Sam, it is intriguing how these circuits come to existence just by a certain desire to gain functionality. It's like we can throw components in any other way and still get any output that can be tweaked through math and then operate properly. I never thought CT could be pulsed. Thank you.

@sambenyaakov

3 жыл бұрын

Thank you for kind note and for sharing your thoughts.

@xDR1TeK

3 жыл бұрын

@@sambenyaakov Sir It is I who should thank you. I'm unworthy.

RATED: 💡💡💡💡💡 9 out of 10 ELECTRONS liked this video. Thank you Professor 👍😁 SUBBED!

@sambenyaakov

4 жыл бұрын

Thanks, but can you decipher this for me?

It's very useful, well-done for explanation

@sambenyaakov

Жыл бұрын

Thanks

Very beautiful explaination sir. Thankyou.

@sambenyaakov

5 жыл бұрын

😊

Very informative, excellent sir...

@sambenyaakov

4 жыл бұрын

Thanks

Nicely and simple explaination give easy understanding

@sambenyaakov

5 жыл бұрын

Thanks

I just learned about the last method and was exploring the time domain characteristics of it in LTspice, but I kept having to fudge the RC time constant value! After an hour of head scratching I realized LTspice was applying a default DCR of 1mOhm to my inductor, which i was not accounting for! Gees I thought I was doing my unit conversions wrong because I kept coming up being an order of magnitude off lol. It's a really neat method, but looks like it can't be very accurate since the ESR of the inductor is a function of frequency of temperature, as is the inductance, causing the output of the RC filter to be under or overdamped with variation to L (like with large DC current bias or flux bias in the core)

@sambenyaakov

2 жыл бұрын

Good points. Thanks for sharing. If not a member: welcome to join www.linkedin.com/groups/13606756

i really the way you describe.. Thanks for this video

@sambenyaakov

7 жыл бұрын

Thanks for comment

You have pretty good kind of english. i am understand all you said even without mega english knowledge. thanks

@sambenyaakov

2 жыл бұрын

Thank you! 😃

very good video, I nirmally use gall sensors with adequate bandwith, but yes once also used a current transformer.....just to had it done in oractice once.

@sambenyaakov

2 жыл бұрын

Thanks for sharing

Thanks. Excellent Sir!

@sambenyaakov

2 жыл бұрын

Thanks

Thanks, very nice explanation.

@sambenyaakov

2 жыл бұрын

Thanks

Awesome video. Thanks 👍😊

@sambenyaakov

3 жыл бұрын

Thanks

Really Interesting .Thanks a lot

@sambenyaakov

4 жыл бұрын

Thanks

Thank you for a video!

@sambenyaakov

2 жыл бұрын

Thnks

It really helps. Thanks.

@sambenyaakov

4 жыл бұрын

Thanks

Superb!

Great as usual

@sambenyaakov

4 жыл бұрын

Thanks again!

Thank you!

Dear Prof. Sam, thank you very much for your video. I am wondering whether 'n' is missing in the equation of Bmax at 13:59. Thank you so much.

@sambenyaakov

5 жыл бұрын

Dear Bin, Thank for comment and pointing out the omission. You are of course correct. I hope that viewers of this video will notice your remark.

@petergriffin760

4 жыл бұрын

Final expression for Bmax actualy do have 'n' term in numerator, corresponding to current Iav. Where else you suppose to put it? Seems correct to me now

Very interesting video! I have only thought about putting a single winding on the main power transformer, using the existing magnetic flux and the seperate 1:1 transformer using the existing input current to switching circuit. However, this brings a lot of new functionality to the table! Thank you. Also, what does j and omega stand for in 18:00 ?

@sambenyaakov

7 жыл бұрын

As I think I have said in the video. I am doing the analysis on any one of the Fourier frequency components (omega) of the inductor current and using the complex representation (j) of the impedance and filter.

@Azagro

7 жыл бұрын

Oh that might be, I must have missed it, excuse me! Thank you!

@sambenyaakov

7 жыл бұрын

All the best

Thanks, I was wondering if you can simply use an extra winding on the output inductor in order to measure the current with a pulse transformer for a dc/dc converter?

@sambenyaakov

3 жыл бұрын

A winding on an inductor does not sense current it senses voltage .

Thankyou very much

This is a wonderful video professor🙏. I'm watching it for the 3rd time and this time, I completely understood what exactly you're trying to explain. There are a few questions that arose in my mind while watching this video 1. In 1st slide: why don't we have a negative voltage spike when current fell to zero abruptly? 2. How exactly does ultra costly 50MHz (AC+DC) current probes work? I'm saying ultra costly coz atleast they are too expensive for individuals to own. 3. Can I make a low cost high frequency current probe by separating out the measurements for AC and DC signals? Using cheap low bandwidth hall effect sensor for DC component and using a pulse current transformer with a range of output resistors to avoid core saturation? Do we get accurate readings by adding these components? Also, is there a better way for doing this accurately at lower cost?

@sambenyaakov

3 жыл бұрын

First slide? please indicate minute of video In commercial current probe the HF portion is indeed based on the AC transformer action.

@rayachotybharathkumar268

3 жыл бұрын

@@sambenyaakov Slide 9-4. Time: 01:01

@sambenyaakov

3 жыл бұрын

Yes indeed there will be a negative voltage spike which is not shown. Thanks for pointing this out.

Thank you very much

@sambenyaakov

2 жыл бұрын

Thanks

thanks

Very Good Video detailing the reset mechanism for CT. @7.10 What type of waveform we can expect across burden resistor whene Ct is not resetted propley or volt sec criteria not met. A sharp return zero instaed of sinusodal return? along with ringing?

@sambenyaakov

2 жыл бұрын

Thanks. Good question. With no reset to core, the circulating current will keep rising, the inductance will drop and I suspect that there will be either a thermal run away, or the circuit will stabilize with a much higher resonant frequency.

@jacobs7281

2 жыл бұрын

@@sambenyaakov thank you for the quick reply . My question was more like there is is burden resistor present and what type of wave dorm I can expect , my under standing from your explanation is that reset will still will be in sinusoidal nature but with higher frequency

Thanks Sir

@sambenyaakov

2 ай бұрын

👍🙏

Sir what do you think of measuring current through mosfets rdson? In very high current drive circuits, not adding one more lossy component and measuring through rdson is very attractive. any advice or contrary idea? thanks in advance.

@sambenyaakov

3 жыл бұрын

This is a good approach. The down sides: temp and current dependence of Rds(on) and the extreme difficulty to implement it in a discrete circuit. Suitable for a monolithic design.

the last one with Vout = I Rs G sounds great... but Delta Rs is HUGE over delta Temperature. So now you have to compensate for that.

@sambenyaakov

4 жыл бұрын

But quite predictable.

@mikeguitar9769

3 жыл бұрын

Here’s an idea. The “differential amp” @19:44 could be implemented in the usual way with an op-amp and 4 resistors, where the gain is the ratio of resistors. Use copper (or iron/steel) wire-wound input resistors (with a tcr similar to the inductor) that are thermally connected to the inductor. This ought to decrease the amplifier gain as the inductor heats up.

Thank you for clearing sir. Sir I am calculationg reset time of CT. Which parameters are important to calculate it. What I understood is ( Secondary side inductance, shunt capacitance are enough to calculate reset time.) Shall I measure L & C at switching freq

@sambenyaakov

5 жыл бұрын

Indeed.

@gregorymirsky8707

4 жыл бұрын

Vicky, at 9:57 there is a very good schematic, comprising a Zener diode in series with a blocking diode shown. As professor Ben-Yaakov mentioned, this schematic is intended for the reset time control. The reset time can be defined as Tres=Lsecondary * Isecondary / (Vzener+Vdiode) The volt*second integral should remain intact. Therefore, for shorter Tres you should select a higher voltage Zener diode and don't forget about selection of a higher voltage blocking diode.

thabk you

@sambenyaakov

24 күн бұрын

👍🙏

Question to 1:20 - should not this voltage spike appears at the end of the current pulse? not on the beginning?

@sambenyaakov

6 жыл бұрын

It will appear at both the beginning and end (high di/dt). I neglected to show the negative spike. Thanks for pointing this out.

RC=L/Rs Very useful equation when the coil wire DC rezistance is steady. Maybe need to compensate the temperature coefficient of the copper wire for high current values? Do you think a NTC in place of(or in parallel to) R would do ? Thanks Mr. Yaakov for the nice videos.

@sambenyaakov

7 жыл бұрын

You are correct there is a temp sensitivity. Inductor wires are normally made of copper which has an appreciable temp coefficient. R is NOT added! it is the resistance of the wire!

@brokensword5042

7 жыл бұрын

I meant R the resistor in serial with a capacitor across the inductor. 17:45 What correction method would you suggest to get accurate (free from temperature ) current feedback from the inductor? (other than larger wire diameter) Thanks.

@sambenyaakov

7 жыл бұрын

Sorry. I misunderstood. Good idea, perhaps somebody else already did it? I don't know. The problem of temp tracking is that in real systems the temp inside an inductor winding might be much higher than the ambient. At any rate, in most applications, there is no need for high accuracy in the measurement of inductor current. This signal is normally used for current feedback and there is no need for precise current measurements there.

@mikeguitar9769

3 жыл бұрын

Here’s an idea. The “differential amp” @19:44 could be implemented in the usual way with an op-amp and 4 resistors, where the gain is the ratio of resistors. Use copper (or iron/steel) wire-wound input resistors (with a tcr similar to the inductor) that are thermally connected to the inductor. This ought to decrease the amplifier gain as the inductor heats up.

Say i have 2 in-phase AC signals, at 200 kHz. i would like to obtain a 200 kHz AC output with current equal to the current-difference between the two input currents. I don't desire a DC or proportional-voltage output. Can i use the CT or other methods? Thx!

@sambenyaakov

6 жыл бұрын

Yes, you can definitely use a CT (one core) with two opposed windings. Remember that the load of the third output winding should be such that the voltage on it will not saturate the CT core. Good luck.

@johnyradio2

6 жыл бұрын

Sam Ben-Yaakov Thx! could I achieve the same using a transformer with 3 windings?

@sambenyaakov

6 жыл бұрын

You need in any case three windings 2 for primaries 1 for output.

Nice video but If it's open circuit CT how can you make a relationship between output current of the CT in terms of measured output voltage?

@sambenyaakov

4 жыл бұрын

Open circuit voltage depends on magnetization inductance.

@namederek3610

4 жыл бұрын

@@sambenyaakov Wow! you're a legend I didn't think you would reply coz the video was 3years ago. Thanks :)

Does the diode leakage current has any significant effect on the measurement results?

@sambenyaakov

4 жыл бұрын

It is usually insignificant being much smaller that the measured currents.

@QoraxAudio

4 жыл бұрын

@@sambenyaakov Okay, thanks for the reply.

can you comment sometime on current measurement at very low values in nano and micro amps

@sambenyaakov

6 жыл бұрын

Look up LPV821

12:55 "the impedance of (the magnetization inductance) must be much lower than (the load resistance). I think you mean higher, not lower.

@sambenyaakov

3 жыл бұрын

Hi Graham, thanks for the the correction of the slip of the tongue. Indeed, the impedance of transformer need to be larger than the resistor as written on slide, and the current lower, which is also indicated.

could you please upload some videos of application examples in industry?

@sambenyaakov

6 жыл бұрын

Will try

Does power electronics designing domain have future.I am interested to work in this domain and suggest me which domain is best and have future.

@sambenyaakov

2 жыл бұрын

Yes, definitely. EV area is growing fast.

Ehh.... this is quite interesting but i'm not sure about some things.... My main question is what happens when you use a step down transformer instead of a step up transformer? Most of the compensation/error mechanisms mentioned herein are caused by measuring a voltage that has been stepped up and the resulting reverse voltage conditions that naturally occur because of that. I suspect that the answer is "impedance", but changing the voltage seems like a guaranteed way to mis-match said impedance, so perhaps not.

@sambenyaakov

6 жыл бұрын

Hi. You seem to have missed the point. No voltage is stepped up. The purpose of the pulse transformer is to measure current. If it will be a step down then: 1. The output current will be LARGER than the primary current, 2. The impedance reflected to the primary will be large, disturbing the current path and dissipating power.

Sir If the capacitor used for measuring voltage is connected to the output capacitor then the Common mode voltage of one of the terminal of the capacitor is constant (equal to output voltage). But what about the voltage at the other terminal of the capacitor. Is it pulsating .

@sambenyaakov

Жыл бұрын

Please indicate the minute in video you are referring to.

@RAHULRAHUL-qy6cw

Жыл бұрын

@@sambenyaakov 20:40

@sambenyaakov

Жыл бұрын

@@RAHULRAHUL-qy6cw the voltage at the other end is the reflection of the inductor current as is. There is a need for differential amp.

@RAHULRAHUL-qy6cw

Жыл бұрын

@@sambenyaakov Thanks sir

why the dc current will flow though the diode but through the Lm, the resistor of Lm is zero to the dc.

Hi I need VTG. Sensing circuit per elect.

Beautifull...at 19:40...

@sambenyaakov

4 жыл бұрын

👍😊

Sam, the secondary voltage v is a derivative of the primary current. If the primary current has a DC component (it is hard to imagine a conventional converter that does not), it should be counted too, since it magnetizes the magnetic core, moving the setpoint on the B-H curve closer to the saturation. The derivative ignores the DC current component. Integrating the volt-second product disguises the real process in the core, since it deals with the voltage value obtained AFTER taking the derivative and thus missing the effect of the core magnetization by the DC current. Therefore the statement "Pulse transformer operation is limited by voltage NOT CURRENT" 14:28 is incorrect since it actually is limited by the total primary current - AC + DC, flowing through the primary winding.

@sambenyaakov

4 жыл бұрын

Dear Gregory, The pulse current sensor is intended to measure a pulsed current. For example in the Drain of a switching transistor, or in the line of a diode. This is the application. In this case, the core is magnetized during pulse time and demagnetized during the off time. What matters then, in terms of saturation is the volltsec imposed on core core, conveniently measured at secondary. Being a transformer, the primary and secondary currents during pulse are canceling each other so what is left is the magnetization current, not the actual pulse current. Regards Sam

@sambenyaakov

4 жыл бұрын

One more point (added to first reply which may appear as second) . The output voltage is NOT the derivative of the primary current! During the pulse time I2=I1/n (save the magnetization current). So V2=I1*R/n

@gregorymirsky8707

4 жыл бұрын

@@sambenyaakov Dear Sam, the secondary voltage v is a derivative of the primary current. If the primary current has a DC component (it is hard to imagine a conventional converter that does not), it should be counted too, since it magnetizes the magnetic core, moving the setpoint on the B-H curve closer to the saturation. The derivative ignores the DC current component. Integrating the volt-second product disguises the real process in the core since it deals with the voltage value obtained AFTER taking the derivative and thus missing the effect of the core magnetization by the DC current. Therefore the statement "Pulse transformer operation is limited by voltage NOT CURRENT" 14:28 is incorrect since it is actually limited by the total primary current - AC + DC, flowing through the primary winding and defining present flux density B." I have a MathCAD analysis of a current transformer from the point of view of the pulse top transfer fidelity. If you have MathCAD I can share this file with you through a personal email.

@gregorymirsky8707

4 жыл бұрын

@@sambenyaakov Dear Sam, yes, it is intended but the DC current is still present even if you put the current transformer in the drain circuitry directly.

@sambenyaakov

4 жыл бұрын

Dear Gregory It is a common mistake to think that a transformer can not transfer an average DC current. This notion is incorrect when it comes to switched circuits. See for example a forward coverter. There is an average DC current component in the primary! What is not allowed is an average DC VOLTAGE on any of the windings. As for the pulsed current transformer explained in the video, it is widely used in the industry. Challenging it is like a person seeing a camel and exclaiming: there is no animal like this😊 In a switched NONLINEAR circuit you need to consider each segment by itself. If you will do that, then during the pulse time the primary current is balanced by the secondary current and then you have a magnetization current which is discharged during the off time. So nothing is violated here.

sir any simple way to identify the phase sequence of three phase supply

@mikeguitar9769

3 жыл бұрын

Maybe connect a motor and see which way it turns?

You should add a practical demo for this ... showing the advantages at different frequencies and selecting actual parts , hence giving a reasonable design pattern for people to implement this in their designs... good presentation though thanks !

@sambenyaakov

3 жыл бұрын

David, Your the first! Out of the 54K or so who have watched this video, you are first and only to complaint: "You should add". I guess all others appreciate the time I take to prepare these videos sharing them for free to all.

Hard to understand. Please explain in detail and speak a little slower. Thanks.

@sambenyaakov

3 жыл бұрын

Play it at 0.75 speed. I am sure that watching it again will help you out.