Inductors in Power Electronics (Direct Current Control)

An introduction to switching current regulation making use of inductors. We test out the theory of stored energy in inductors, and utilise one to smooth current from a switching MOSFET. We then look into the need for a flyback diode in such a circuit, and finally consider the basic options for control schemes.
What happens when:
0:00 Introduction
0:19 Why current control?
2:17 How inductors will help
4:23 Target current hysteresis (DCC)
6:44 Does the theory hold up?
9:12 The BIG problem with inductors
11:12 How a single diode can fix the circuit (flyback diode)
13:06 Controlling the MOSFET using PWM
17:32 But this circuit does nothing?
18:30 Conclusion
18:42 Outro
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[@Kareem-Ahmed]

It's great that you show the equations, explain and apply them into real circuits + you don't play a distracting bg music. 👍✌

[@electrarc240]

I usually try to avoid equations to keep things simple, I only show them if I can prove them to you all with a real demo! Thanks

[@Kareem-Ahmed]

@@electrarc240 Keep up the good work.

[@johnnytwotimez]

If id had a teacher like you, id have been something.

[@electrarc240]

You do now! It’s never too late to learn :)

[@editfarkas4503]

I found your channel just a few hours ago but I'm sure I'll watch all your videos starting with the first. I love your style and your clear and logical approach. 😊😊❤❤

[@markkrumpelman3973]

Best an most informative video on youtube for simple circuits, for all of us that only know basics. Please keep them coming. Thank You

[@electrarc240]

Thanks, more to come!

[@jboy6944]

Bro, this is absolutely GOLD. Can't express how simple you made it. I wish I could have this level of understanding!

[@electrarc240]

Wow thank you very much!

[@JohnSmith-uy7sv]

understanding of what?? 🙄🙄🤪🤪

[@d614gakadoug9]

In the waveform where the voltage is going to 85 volts, that particular voltage has nothing to do with the inductor, as such. It is the result of causing the body diode of the MOSFET to avalanche. It stays at the avalance voltage until the energy stored in the inductor been discharged. Avalanching the diode can be destructive if there is sufficient available energy/power (they are generally rated separately, hence the slash). In some circumstances it is perfectly safe to allow it. Note that at all times the drain of the FET is positive with respect to its source.

[@keithking1985]

That was one of the if "NOT" the best explanation of PWM an inductor. Yoy just got a new subscription. 👍☺️🇮🇪

[@gilbertvelez4756]

Thank you for proving that the driver I designed will work. I'm using an h bridge to isolate and increasing voltage on the secondary then running a bunch of 50w COBs in series, limiting the current to 1.5A. That 200ma window using a flipflop and comparators, maybe a little signal filtration and there's uninterrupted light, which is ideal.

[@MXstar189]

when first learned about inductors I was amazed by what they can do for example a "boost converter"

[@electrarc240]

Yeah same, still not over the initial excitement of that revelation tbh 😂

[@chrissmith7655]

Hi ,thanks , the beauty of your series is we can watch it over and over again until we understand haha. Keep them coming, many thanks.

[@philippusschutte3093]

Brilliantly explained thank you.

[@ivoryas1696]

11:39 "Ah, yeah. It's all comin' together" But seriously. Getting a feeling I'm actually getting a handle on this stuff, lol. 13:08 Agreed, man.

[@francoisguyot9770]

I love your analysis.

[@danbrown8872]

Perfect explanation 😊

[@brucekempf4648]

Great video! You explained this subject so well. Thanks!

[@badgermcbadger1968]

I already knew the subject, but clicked out of curiosity. Quite a good explanation, i approve

[@RichardFreeberg]

A wee bit of calculus without mentioning it. Nice. LOL. Seriously, I like the presentation. You would have lost a lot of the audience if you'd gone the full dt/dx and first second derivatives, eh? The fascinating thing is how dynamic inductance / capacitance phenomena are, and how our 'maths' can tame them! Thumbs up!

[@senorjp21]

Excellent explanation and demo

[@BillDemos]

Very nice videos, I like your step by step methodology in presenting subjects, subscribed instantly. The inductor is the analog compliment of the capacitor: a capacitor once charged would short-circuit (lose charge) if we touch its leads, an inductor needs its leads connected once charged so that it does not lose charge (and keep the magnetism not collapsing)! In a perfect world where the inductor was made out of a super-conductor, the current would keep on going. In this world we are in, however, we have ohmic losses, so an inductor cannot possibly compete with a capacitor in this area. A capacitor can remain charged with no losses, indefinitely. Therefore, in any power systems where you care about efficiency, you would use a capacitive design, as they do for mobile phones (the voltages are upped or downed with putting capacitors dynamically in series and parallel, and the current is supplied by how many charge transfers you do). In the design here, you are using a diode to keep its leads connected in the off-cycle, and this introduces a huge amount of losses. You see, a photovoltaic cell, an LED and a diode are the EXACT same devices (believe it or not!), with a slight change in bang gaps. The simple p-n silicon diode is like effectively having an infrared LED turning on every time it is forward biased!! The perfect solution here is to have a field effect transistor also on the top side, instead of the diode! You energise it when you de-energise the bottom one, so you could have it on a single wire if you use p and n types for the top and bottom transistors respectively. That way you have extremely low losses (a good transistor nowadays has a resistance at the range of milli-ohms when turned on, it has a negligible voltage drop). Also, for very high frequencies, or for excellent synchronisation of the two transistors, you could count the nano-seconds it takes to energise and de-energise the gate for each one, depending on the voltage you are supplying, and you could apply the correction time offset with a microcontroller. If you are wondering how you could connect both of the mosfets on a single signal, on a single wire, you could have a look at the videos I have uploaded on my channel regarding the CMOS not gate. Best regards :)

[@electrarc240]

Superconducting inductor, sounds like an MRI scanner. Thanks for all the info!

[@BillDemos]

@@electrarc240 Yes, they use them there... An inductor like that would be very happy in a closed circuit. It would be the equivalent of the quality we enjoy with capacitors: the charge is not lost, until you need it. For example, in a system like that, once you do the initial charging, you would leave the top transistor closed while opening the bottom one. The energy would just exist as a magnetic field, until you need it.

[@electrarc240]

@@BillDemos Oh how we dream... Maybe one day

[@onenewworldmonkey]

I just subscribed after watching your popular video about power supplies. I know enough to be dangerous. I'm commenting about an extremely popular problem that I'm sure would get many views. I (like thousands of others) bought a VFD and read in the manual that I should have "AC reactor" and an "Input EMC filter" before the VFD. (My VFD powers a 3hp motor that is normally 3 phase but the best I can do is single phase 240v). As for the AC reactor ebay has them for around $300 which is what I paid for the vfd. I've been told I can use a used 3 phase one if I use the outer 2 coils. Then I found a guy who made one for less than $20 by cutting an iron pipe and wrapping wire around it. He ended up with around 5% inductance, which is what is recommended. I am not alone with this problem. If you could made video about it I'm sure you would get everyone who bought a vfd to watch it. Should I buy one of those big 3 phase ones, could I make one with an iron torroid, how does one size a filter, how about just a surge protector, where do babies come from, what is the capital of South Dakota? All these questions keep me up at night. Thanks for your great videos

[@electrarc240]

Hmm pipe sounds a bit dodgy I would imagine there would be a lot of losses. I can have a look into it though as I recently got the kit to characterise inductors so can test custom ones. As for babies, absolutely no idea I'm afraid...

[@DifficultyEasy]

AMAZINGLY well done!! NEVER seen anyone explain concepts and relations this clearly and using the actual components to demo! If you wouldn't mind, would you ping me to check an explanation on MOSFETs in a circuit I'm preparing? Much appreciated and keep this up! Much needed!

[@ChristosBassCovers]

Great math explanation

[@colicarot]

Very nicely explained ! you would be a good teacher !!

[@electrarc240]

Maybe one day I will be one!

[@harunservice8376]

Simple projects 👍

[@mahmoudbitar6571]

Please make a video about Oscilloscope, i am a hobbyist and i love to see a video made by your way of explanation

[@electrarc240]

Hmm that's a good idea, I usually avoid using them because they can confuse people, so clearly they need a video making about them!

[@EnezReyiz]

Very informative, thanks a lot

[@electrarc240]

Thank!

[@hogeojin]

Really nice explanation with real components and scope screen.　Thank you!

[@K.D.Fischer_HEPHY]

Very nice and practical explanation.

[@rrangana11]

Thanks...Nice explanation.

[@bennetting1609]

More ElecrArc in my life is always a good thing, keep it up! Also that's a fancy outro you've got now.

[@mkenya_engineer]

A very important video Sir

[@irfansami3335]

Best video I ever had. Answers to all of my question going in mind. What inductor is doing in the circuit,... :D

[@yt4krist0f]

Perfect explanation, enjoyed to watch, keep on going!

[@mike-yp1uk]

Totally awesome video and I've never heard it explained like this.

[@makimcleary393]

Great explanation as always. Thank you very much, I'm looking forward to the next ones!

[@electrarc240]

Thanks, glad you enjoyed it!

[@dannyperry8070]

nice job sir

[@mertali7605]

Good explanation, thanks.

[@electrarc240]

Glad it was helpful!

[@peterlethbridge7859]

a really good video, well explained, smart young man.

[@shawncalderon4950]

Superb presentation skills! I have watched a lot of KZbin on the topic, and few are as good as this channel. I wonder if the glamor face close-ups are a bit off-putting to the browsing electronics hobbyist. Keep the camera on the topic and let your butter voice unravel the near-insurmountable mysteries of electricity.

[@electrarc240]

Thank you very much! And yes I’ve been working more on hiding my money maker!

[@shawncalderon4950]

@@electrarc240 Please forgive my rudeness. You are a gifted, talented, genius teacher; let no one tell you otherwise!

[@electrarc240]

@shawncalderon4950 ah don’t worry you weren’t rude I’ve had much worse haha! Thank you again, I’m hoping to make more videos in a few months when I’m done with uni.

[@shawncalderon4950]

@@electrarc240 Is uni short for university? I'm a retired military veteran from Chicago and am unfamiliar with that abbreviation.

[@electrarc240]

Yes it’s for university. I will be working next year so should have more time for this. I’ve been very busy this year

[@ccv3237]

Very well explained! Congratulations"! I'll be looking for your following video.

[@kevinfrack8217]

I'm stuck on a problem I need a solution to! Think this video may be close to the solution. I need a Vampire power supply, that can give a regulated 5v dc @1amp, No matter what the AC input voltage is. An operational example: Have an electronic dimmer on a lighting circuit say 100w bulb we need to generate the 5v dc no matter what that Dimmer or Variac is set to (20 to 100 percent) Any help is be appreciated. Love your videos they are very Good, You right get to the point, and you are good at making them understandable for us average folk.

[@electrarc240]

A simple linear regulator like a generic 7805 is the simplest way to get 5VDC@1A, I would use one of those as the final stage of a PSU, but they can only take up to around 35VDC on the input so preceding that you'd want something else. simplest would be a transformer with a rectifier such that the output would always be between 35VDC and maybe 7VDC. this wouldn't be very efficient or compact though. Really you want a switch-mode PSU which you could maybe achieve by rectifying the mains directly then feeding it through a circuit similar to this, but with voltage feedback rather than current. This wouldn't be isolated though so definitely shouldn't be used for anything a human could come into contact with. I'd look into buck converters, or forward converters if you need the isolation.

[@haczyk84]

Good video.

[@MickHealey]

I like these videos. Very clear and well explained. I also learn stuff :-) Well done and thank you.

[@electrarc240]

Thank you very much!

[@williamb3323]

Just found you and I subed. Thank you for this work. Appreciate it.

[@jasonjaffray4025]

MASTER TEACHER THANK YOU!

[@electrarc240]

Thanks!

[@jimbo5728]

Great explanation!! ⭐️⭐️⭐️⭐️⭐️

[@KuKu427]

Thanks!

[@leehewitt9559]

Great description and explanation. 👌

[@bob_mosavo]

Thanks 👍

[@pietrodagostino5451]

Execellent . A little to fast explanation.

[@nickush7512]

Excellent resource, thanks.

[@kabandajamir9844]

So nice thanks

[@HTSpecOps]

Awesome video, subscribed !

[@electrarc240]

Thanks for the sub!

[@jj74qformerlyjailbreak3]

My arsenal full of great content said your channel will fit in just nice and never sooner. New Sub earned. Well done. Well done.

[@n30cortex49]

Very nice I've basically just startet making this my new edgy hobby. I've learned a thing and english ist not my native language. So really good job. xD I'll stay around some time. ☕

[@TOMTOM-nh3nl]

Thank you

[@lorddonpromillo4836]

Love the videos. Keep ingoing. Pretty sure the youtube algorithm will push you soon :-)

[@electrarc240]

Thanks!

[@evanlane1690]

Awesome!

[@TheAmity]

It raised some questions about where the MOSFET's gate is hooked up. why didn't explain about the capacitor and push switch? why you didn't show the final & the whole schematic with their component numbers/values?

[@jozsiolah1435]

Samsung hides this component, so I checked on what it really does. Blacklisted power banks, stolen ones use the winding to self drain the battery, it becomes very hot. During normal charging it is warm. It is designed to self maintain the battery during normal use. I am not sure, if it has radioactive memory effect for a while after it is bought.

[@tejenprajapati5512]

nice proj ect

[@pfrillele]

It would be good if you use the right units in the formula,t in ? L in ?

[@graemetunbridge1738]

15:00 the inductor current limit is presumably your powersupply current limit ?

[@MXstar189]

its the collapse of the magnetic field that generates that voltage spike @ 10:00

[@Enigma758]

Wouldn't a capacitor at the output reduce the ripple?

[@electrarc240]

Adding a capacitor can lead to a less uniform current waveform which makes this kind of very basic control less stable. If you make this circuit properly with a microcontroller adding a capacitor would make more sense. I will try and make a video covering that in the next few weeks if I find time.

[@xvillin]

What if we don't believe the equation or your oscilloscope? Could you please lick the inductor, turn it on and tell us how it feels?

[@ghanrajsingh7347]

Like your videos sir

[@electrarc240]

Glad to hear that!

[@indopakcurrentaffairs435]

What's the number of this MOSFET?

[@electrarc240]

Toshiba K30A06N1

[@diyfamily6848]

Yes but you controll current with voltage, but you monitor the current.

[@pietrodagostino5451]

"Too" instead of "to"

[@TheTransporter007]

Framing... slide that camera back a foot or two.

[@Snowsea-gs4wu]

I like the framing as it is…

[@johnconrad5487]

college student? equations are good except that E = - Ldi/dt. you connected the scope clip to the positive power and the scope readings are upside down. seems like a little bit of a mess. when you first saw the flyback pulse going down that should have been your clue to correct the scope probe connections.

[@electrarc240]

The clip is on the source terminal of the MOSFET to allow simultaneous measurement of Vgs, Vds, and Ids (inverted). Connecting different ground clips to different potentials would have resulted in a little bit of a mess.

[@garypoplin4599]

6:47 - You speak out your mouth, not your eyes.