Optimal Regenerative Braking, Explained (episode 14)

This week we look at how motors can be used for regenerative braking and the unintuitive reason why friction brakes can make them more efficient. As always, like, comment, subscribe, have a great day. but only if you want to. P.S. sorry if the meme density was too high.
footnote: 100% duty cycle corresponds with the generation method described in the first half of the video.

[@mrrkrr]

Watched so many garbage, surface level videos before finding this one which actually does a good job of explaining things. Thanks so much for making this and explaining everything so well!

[@chandan-qx1br]

bro where are you only one playlist the world deserves people like you please come back and do more videos its my humble request. oh god you're great man and this is the end of this playlist

[@calvinso]

This is by far the best video I found about regenerative braking

[@blackmanops3749]

By far the best explanation of regen braking. Thank you.

[@aaronsingh6496]

I was having some questions on this subject..i accidentally came across your video..and I'm glad i did. Thanks for your effort. It is a great help.

[@rafaobrs]

maaaaaan! that series is awesome! I can't even imagine the tremendous amount of work you put in those animations! Thank you for that! If you are looking for other topics, I think there is one thing that no one is trying to explain anywere, at least I could not find it: How to measure/calculate the rotor flux angle on multi pole motors? This might be something simple but I can't understand, it even seems more complicated when I realize most motors have different numbers of poles in relation to the number of stator slots, I simply don't get it. If you know any documentation about it, please leave a link. Thank you!

[@Ritiange]

OMG this is the best video regarding regenerative braking, thx for the amazing video!!!

[@teo4807]

Absolutely fantastic channel. Subscribed.

[@parthraut9020]

amazing series, loved it!

[@yaqwsx0cz]

I love your video series!

[@iraqi6207]

👌 that was intensive, yet very neat : )

[@pokpikchan]

I was trying to charge a battery by running on a treadmill. This is exactly what I was looking for. Thanx

[@Howdidyoufindmehere]

Great video and explanation

[@satlal9802]

This is a brilliant video!

[@TVbr7]

Underrated, Thank you

[@prasannarn946]

This video is awesome!

[@TheNichols]

I loved the video and you do a great job of showing how the regenerative braking system works. However, I must admit that I'm a little ticked off by the explanation. I was under the impression as a new electric car purchaser that I would be buying a car that had some inherent benefits such as less maintenance on brakes due to regenerative braking. Personally, I like the idea of recharging when I release the brakes but I don't want for the car to ever use the pads and would rather sacrifice the added battery power for longer brake life. My car will go 226 miles on a charge so I have more than enough to get where I am going under normal driving conditions. I have read the manual on my 2021 Nissan Leaf SL Plus and it doesn't really tell me exactly at what point the pads are being apply other than when I depress the brake pedal. I'm not sure whether to use ePedal or B drive mode or just drive in normal D mode. The user manual is not clear.

[@user-el8kx7qd2r]

Capturing the currnet in a loop was real something 😂

[@jiayishen374]

Nice video！

[@anthonyboarman3833]

Gee this goes way over my head.

[@sayanwar87]

Very good explanation. Can you also elaborate on the control techniques for using the inverter switches in regeneration mode? Is it just reverse SVPWM or any better technique?

[@TheMechatronicEngineer]

You should keep your YT channel alive, it was good!

[@neptune8422]

great video!

[@jtlee1108]

Thanks!

[@bernardcharlesworth9860]

Be interested in how a super capacitor could be used to improve energy transfer to battery.finding the regenative pulses very choppy which can't be good for chemisty

[@ivanchizhov4081]

Thanks!

[@leavoa]

Hi, great video! Really appreciate the time you take to make these videos and animations! Quick question, at 2:20 , shouldn't it be Kv, instead of Kt?

[@jtlee1108]

thanks! so I will start with the caveat that I haven't read every motor data sheet by any means, so what I say may not apply to how every manufacturer reports their stats. in my experience, the torque constant is typically listed in N*m/A, which, if you convert things over will be equivalent to V*s (which, expanding is Volts / (radian/sec)), so multiplying by the speed (assuming you are in rad/seconds) would give you the voltage of back EMF produced. alternatively, you could use the speed constant (as they are, at the end of the day basically telling you the same info).The speed constant is typically given in RPM/V, so if you divided your rotation rate by your speed constant, you should get the same answer. The reason I tend toward using the torque constant as a rule is that I tend to think of motors in a sort of bond graph sense (en.wikipedia.org/wiki/Bond_graph, its not a super common topic, but I had the opportunity to take classes on it). in this notation, you can think of motors as gyrators which bridge domains (I.E. going from the electrical domain to the Mechanical). And, when doing this, it tends to be easiest to just use one gyrator ratio where I*kt = t and W*kt = V. So, all that to say, I believe you could use either Kv or Kt, but if you use Kv, I believe it should be w/Kv, and you would need to make sure w is in the right units. hope that helps, and thanks for watching!

[@leavoa]

@@jtlee1108 Yeah that makes sense! I tend to use Kv when dealing with voltage and speed, and Kt when dealing with torque and current - my personal preference. Though I do concede it creates confusion as it implies a motor is defined by two different constants when in fact they are reciprocals of each other. Cheers for the interesting video!

[@06howea1]

Wow dude u r genius

[@thorlancaster5641]

It'd be nice if there was a setting where the car could only use the brake pads when absolutely necessary, energy losses be damned. Since the motor will be the only rear braking source for my e-bike, I'll have to do this. I wonder what the real-life difference in efficiency will be between: 1: Limit braking torque so it doesn't hurt energy recovery 2: Limit braking torque only when you're shorting all 3 phases together 3: Never limit braking torque, even if you have to shove energy into the motor to help brake faster.

[@RNA0ROGER]

So could an electric car motor be used as an alternator in a diesel electric system?

[@raulnicolasmayamaceda3597]

Do these equations work for all types of AC motor? Could you share your bibliography with us?

[@kablammy7]

what about gearing up the rotation of the motor so that the wheel spins the motor faster during breaking ? ( if CVTs could be made workable - this might be a good implementation for them ) next - what about having a separate set of batteries that are more depleted than the main set - so that upon acceleration, these batteries are highly depleted and then during braking they can capture more of the regenerated power ?

[@widyaagungfathoni68]

What about ac motor? How regenerative braking on ac motor work?

[@nextinspiratortv7277]

where can I explain this through writing articles?

[@sanchit1677]

Great Series. Why you stopped?

[@biswajit681]

Please continue your video

[@Jmoneysmoothboy]

Maybe brushed motors where the brushes are used as brake pads because you don't have to power brushes you could just squeeze them

[@QwertyCanada]

What software did you use to make the video, really cool animations!

[@jtlee1108]

I use affinity designer to draw everything, then I animate the PNG files in apple motion. Vocals are recorded in logic, and everything is cut together using final cut X

[@biswajit681]

Could you please continue this series

[@vevenaneathna]

uh is this more true for teslas with their non magnet motors? around town in my volt with master race rare earth magnets i regularly get 5-7 miles/kwh. feels like i dont have all these efficeincys and fet switching trickery, its just a magnet spinning...

[@georgederleres8489]

Does the experiment at 7:30 apply also to a 3-phase motor, or is it not so simple and intuitive there?

[@ME102Group9]

Why did the videos stop? Great video series!

[@jtlee1108]

Thank you, I hope they were educational and at least a little entertaining. As far as why I havent made more, I am finishing up my doctorate and havent had the bandwidth to keep making them. maybe one day I will pick it back up but if I do it'll likely be a bit from now, and I think I would branch out from just motors/motor control. Was considering doing a series about the ideas in the Neville Hogan papers about Impedance control, just because I have never seen that explained super well in an easy to consume format and they are important ideas

[@johnrbnsn]

Make some new videos, your stuff is great!

[@billjohnson3366]

ummm why wouldnt u have a second generator that is oynused fir breaking and it replae the break pads setup?? tjat u can jave ir motor optamize the regen like he explained but then fir tje additional stopoing power it would engage the secondary generator instead if break pads so u can regen even more.. cuz any time u squeeze a tire to stoo it u are throwing away all tjat energy inti friction and heat

[@gabedarrett1301]

9:08 I didn't know regenerative braking had controllable torque!

[@saurabhborude3385]

Why don't you upload videos anymore? 😕 Your videos are very informative!

[@jtlee1108]

Haha I appreciate it, but life has just gotten busy finishing up my graduate work and such. Maybe one day ill make some more, they just take a whole lot of time

[@saurabhborude3385]

@@jtlee1108 will be glad to see you back soon. Best of luck!

[@larsdigerud8257]

Love your videos! Where do you get these formulas from?

[@jtlee1108]

thanks so much! so the majority of these are developed/talked about throughout the series, do you have any in particular that are confusing? im happy to give feed back on whatever.

[@larsdigerud8257]

@@jtlee1108 Guess I have to study your videos more! Im doing a research project where I am using regen at the moment and im now trying to achieve the sweet spot with regen

[@06howea1]

It will ultimately come down to the way in which the oem software is written... Right?

[@jtlee1108]

by 'OEM' do you mean original equipment manufacturer? If this is what you mean by the abbreviation, this series is primarily about motors which are not sold with prefab controllers, where you write the software for commutation.

[@frankstocker5475]

I got into 4 minutes & gave up.

[@TheZambie1]

Is it just me or does angular velocity look like a pair of trip D's?

[@georgederleres8489]

It's really hard for me to understand that last part. Since mechanical braking reduces the speed and thus the Back EMF, how can it even assist the regeneration ? I mean I can understand it's usefulness when high braking torque is required and it cannot be achieved just by shorting the phases + connecting them to battery afterwards. But is it increasing the energy or just helping the optimal PWM duty cycle for regeneration?

[@carelsberghstijn]

Didn't you say in one of the episodes that there are 15 parts?

[@jtlee1108]

good catch, originally I had planned 15 parts, however the feedback control episode ended up covering the topics I had planned for two episodes well enough that I cut one from the series. Ultimately, I just got a little bit too busy with my doctoral work to keep making videos for now.

[@carelsberghstijn]

@@jtlee1108 oh okay, anyway, great video series, with what did you make the animations? Planning on making more video's if you have time again?

[@ameralmhtachem499]

I understood everything untill this part. 1:25 Then I kinda lost it.

[@LivyuFPV]

How can I contact you ?

[@jtlee1108]

what's up?

[@LivyuFPV]

@@jtlee1108 everybody is doing theoretical waveforms but nobody is doing actual measurements on a scope. From gate to vgs waveforms. Theory is one thing practice is another. I feel that people should have a reference from real life measurements. :) often times real measurements are not thory like, hope this helps.

[@LivyuFPV]

@@jtlee1108 example: what a high dv/dt looks like, what to look for in a weird gate signal...etc

[@guywhoknows]

But isn't the torque a undesirable effect when braking? If you draw current, this would slam the motor and cause a fast stop, but it would be a large spike. Usually way outside the capacity to " translate" the power.

[@jtlee1108]

the torque we are talking about is negative, braking torque. also the currents you would generate are relatively low, and typically a motor would be connected to a higher inertia system. Because of this, it would, in most all cases, slowly brake the motor to a rest.

[@guywhoknows]

@@jtlee1108 the torque and draw are almost equal, the unforseen is how long your want to stop, or how short and the power generation. It cant be one size fits all. Same as with motors. I've seen high current from using DC motors and with a lower voltage. I don't believe the same occurs in AC?? But isn't the torque when stopping on regen amp'd but the transmission ratio at the wheel?

[@jtlee1108]

the torque during braking will have the same transmission ratio applied as it would when driving (assuming you havent switched your gearing). the only difference is that the torque is produced by current which is being driven by the BEMF of the motor, as opposed to your battery/source. As far as stopping time, you can wrap a current control loop around your braking torque and vary your duty cycle at which you are PWMing your motor leads together. In this way, you can specify the braking torque you want out of your motor.

[@MichelJosephCardin]

What I'd like to know is if this regeneration system would charge the battery to full if it were to be continuously rotated by force? That is the only thing that is really important; because if it could; then it could charge the car while you are sleeping; if it were to be connected to a wind turbine that would be what could even be part of the vehicle. Because that is really what everyone want; free energy to run their car; that is everyone that isn't making money with selling energy.

[@jtlee1108]

To answer your first question, yes, it could. But to go a bit deeper, this is how turbines (wind, hydro, or gas) work already. They turn a generator, which is essentially a motor by the force of whatever is supplying it. This then generates a current and a voltage, which is put onto the grid. So, if we set up clean energy infrastructure on a large scale, this would be what happens while you are sleeping, only your car wouldn't need to have the added weight of a built in wind turbine; plus efficient wind turbines are incredibly expensive and produce an absolute boat load of power, so it wouldn't be practical on an indivicual level. anyway, yeah, turbines are cool.

[@MichelJosephCardin]

@@jtlee1108 This wasn't quite what I'd been asking; I was asking if we were to build a simple blades part of a turbine generator and maybe even have it within out homes' attics being the inductors and having a quick connect to our electric car's drive train or even better yet the part that would then be a free spinning shaft that is now the link to the torque coming from that braking system. and this way there would be less of the vehicle's drive train being used. I'm also sure that the stator that is use could be built and one could go direct to the next part. The blades part of a turbine doesn't really need to be heavy; and I'm not sure of how much resistance that the head on to wind is but that could also be used while going forward.