Understanding Regenerative Braking!
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- Опубликовано: 30 авг 2023
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Love the attention to detail with the BMW not indicating for the corner. Keep up the good work.
Ha, yep that is accurate.
But bmws have regenarative breaking..... there is no accuracy... All bmws have 48volt motors to enhance performance..
@@blocksource4192Do you mean hibrid or efficiency dynamics ?
🤣
@@AkmalPROMVP they all have mild hybrids…
Regenerative breaking is also used by trains and trolleybuses and the energy is transferred back to the network
Some elevators and bikes have regen braking too
@@frommarkham424 Yep, I was in the fitness industry and they used it on the Precor 846 bike and 546 cross-trainer about 20 years ago.
Applying friction brakes for complete stop no longer required when optional setting is enabled
The rear motor in Tesla, Volkswagen and Hyundai electric cars is not the induction motor you have represented in the video. They all use a Permanent Magnet Synchronous Motor (PMSM) but the video is still valid because the principle of regeneration is the same. The only difference is that rotor and the stator magnetic field rotate at the same speed: the machine is synchronous. Thanks for the good video.
LR AWD Model S and X used to use a PMSM on front axle and induction on rear, whereas the 3/Y use induction front and PMSM rear. Since the refresh launched, they’ve used 2-3 PMSM motors. This is a little bit of a dent in efficiency because the PMSM generates a force each time it spins around even when no power is being fed to it. This is why Hyundai/Kia/Genesis, Mercedes, Porsche, Audi, etc. all fit a mechanical decoupler to one of their PMSM motors so it doesn’t spin and create drag when not needed for power. It’s honestly a little surprising Tesla didn’t keep an induction motor on the LR AWD S/X or invest in a clutch to decouple one or two of the motors from the drivetrain like the Germans and Koreans have done, but they didn’t. Hyundai claimed the addition of the clutch system improved cruising efficiency 9% on average on their AWD models. In my experience it’s closer to 20% at highway speed.
@@fields1 The front induction motor is barely used in normal daily driving and only when it is needed.
@@icy1007 on Model 3/Y, yes. On Model S and X which no longer use an induction motor (they’re using 2 or 3 permanent magnet motors) obviously that isn’t an option.
On the S and X it would be ideal to switch back to induction or to add a clutch to the front motor to decouple the motor when not needed (pretty much anytime you’re not hammering it) like Hyundai/Kia, MB, etc. use on their EVs with multiple PM motors.
Nissan's used the PMSM since 2011. Weird that everyone seems to forget about Nissan.
@@casey360360 I still have my 2011 Nissan Leaf, I'm constantly trying to forget about it. :)
Id imagine a similar or the same principle is used on hybrids. I own an 07 civic hybrid and I love coasting as long as I can to a stop and watching the hybrid battery charge. Not only will this increase your city fuel economy in a hybrid but it also will significantly reduce the wear and tear on the brake pads if you make it a point to take advantage of this system.
All true, but regenerative braking systems will still employ the friction brakes at times, because optimizing energy recovery while also stopping the vehicle means strategically drawing braking torque from the friction brakes, rather than relying entirely on engine/motor braking over the entire deceleration curve.
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This video is very informative, thank you so much Tesla. Keep up the good work ❤
2:55 I am not sure about Tesla EVs in particular but in general, the power produced from regenerative braking by the inverter is in DC format only. Inverters normally change DC to AC so when operated on reverse, they change the AC power from the motor into DC. So there is no need for an additional rectifier.
But this DC power needs to be brought to a the right voltage for charging the battery, which is where the DC to DC converter comes in. Another interesting thing is that usually this part requires very little additional hardware, as the on-board charger used in most EVs also consists of a DC to DC converter - and that same one is used for charging the battery during regenerative braking, as the on board charger is not in use during driving.
Not even close. The FET/diode circuit in the inverter works as a rectifier during regen, the inverter has a PWM circuit to act as a buck-boost converter. Regen is contained 100% in the inverter, regen force is also controlled by the inverter. The DC-DC converter only steps down voltage to the accessory battery. Level 1/2 charger is done by AC rectified and stepped up to battery voltage by again, the inverter. level 3 charging is native DC from the charger.
@@casey360360As for the first part of your comment - that is exactly what I said. The inverter rectifies the regen power and there is no need for an additional power converter for that.
Regarding the need for a DCDC converter - firstly I am talking about an HV to HV DCDC converter, not the HV to LV converter for the auxiliary battery. Secondly, the video already mentions that the architecture they are describing uses a DCDC converter to bring the voltage to the HV battery voltage. This is a very common characteristic of many EV architectures in the industry today, as they want to support 400V DC charging which is more widely available than 800V DC charging, but they still want to have an 800V inverter, heater, a/c, etc to improve overall efficiency. Of course, there are EV architectures where the inverter regen voltage is directly at the battery's voltage level so there is no need for an HV to HV DCDC converter, but that is not the kind of architecture they are describing in the video.
Regarding level 1/2 charging through the inverter - yes that is one of the features of a few modern EV architectures but most on-road EVs today have a separate On-board-charger and inverter. Watch any teardown video and you will see.
Great video as always! Keep up the good work👏💯
Love the data
Super love the voice
Its interesting and
Easy to understand.
Great info. Super efficient
Fantastic explanation. thank you for sharing sir
It would be interesting to see how Tesla has been achieving a very precise control of the vehicle movement at low speeds now, it seems like it actually uses energy when coming to a stop at low speed downhill and I would also presume on a flat surface too, it's just negligent compared to the energy needed to stop at downhill scenarios
Lorentz force vector should point in the opposite direction. This mistake probably occurred because the direction of the induced currents in the rotor is also wrong.
Tesla now allows regen braking all the way to a full stop. It use to be to about 5mph before the friction brake was needed…. Now I haven’t touched my brake pedal in a long long time
Its the best thing since sliced bread. It is a much more relaxing drive when you barely have to lift your foot from the accelerator I can't imagine driving a car without it.
Is the regen really doing all the braking, or is the car just automatically applying the friction brakes for the last bit?
@@adrianthoroughgood1191 The car automatically applies the friction brakes. In fact, teslas have power meters that show how much energy is entering or leaving the battery, and if you take your foot off the accelerator entirely and let the car stop itself, it doesn't show any energy entering the battery anymore after it goes below 2 or 3 miles per hour.
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It is probably quite similar, but I would love to see an update with the permanent magnet motors, and how they use one pedal driving right down to Fu stop.
It’s much more simpler. Permanent magnet motors are synchronous, they do not need any input to generate power, their frequency is synced to their rotation rate. To regen, just simply pause the inverter and hook up a rectifier is all you need.
They can either blend in friction brakes or use "plug braking", basically using the motor backwards (actually consumes power).
Even permanent magnet motors need to blend normal brakes below 3-5mph. It’s just automatic with EVs with One Pedal Driving
@@j.phoenix technically they can using what's known as "plug braking" but it actually consumes power instead of generating it.
@@sethflorentz4809 Not a single EV uses plug braking. That would be moronic.
Really well explained
Interesting way of using the car break system 👍
Excellent video! Had to watch a couple of times 1:53 to 3:10 was the answer I was looking for.
Very helpful I now understand 🔥👊
You told that inverter keeps RMF speed lower than rotor speed by applying specific frequency current. And then inverter takes back power from coil. How does you can control the frequency of current when you are drawing energy from the coil?
I drive all the time never hitting the brakes. in combination of my timing and Tesla got real good at giving the right amounts of regen. I knows if there is a stop sige or red light coming up
It is really good video
Thank you 🙏
What programs do you use to make your videos?
Great info Thanks
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Could this be used for everyday bikes?? Not when braking of course but when peddling or going downhill to accumulate the energy but into it to use later?
If it worked like EVs, you'd lose speed going down hills if you used this technology but you'd be able to use it to go up hill at least.
I think some E-bikes have similar tech to what you are asking.
I personally wouldn't trade my fun bombing down hill at 50mph on a bike or coasting for miles for some uphill convenience but I'm sure many would.
Guess it'd have to be a toggle for on/off when you wanted it, ideally.
Also, regular bikes have this too already, to charge headlights and cell phones, look up "dynamo hubs" for bikes.
There are many Ebike models with regen braking, but just like the video noted, efficiency greatly decrease at low speeds, so the additional range you get is much less than 10%, making it less important of a feature.
It's been a while, thanks.
Always wondered how the brake lights would work with that, and the effect on rear end collisions
I think they are controlled by the computer. I know in my car as soon as I barely reduce pressure on the accelerator the brake lights come on, I don’t have to press the brake pedal.
#1 question asked on Tesla test drives, they say. The brake lights are turned on when braking, automatically. The cartoon version of the car on my screen shows the brake light illuminated.
It's not just EVs, modern gas cars have special brake light logic as well. For example, when you are in hill hold/auto vehicle hold, or in collision avoidance emergency braking, the brake lights will turn on even though the pedal isn't applied. This caused an issue with the new Ford Ranger because they forgot about this when designing their trailer brake controller, so there's a stupid harness running from the front through the roof to the CHMSL to get a braking signal.
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Thank you
Which software is used to create these videos ?
Wow! A bike lane!
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Please.. Video about in wheel motor design & technology
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I have a query:
My electric car shows "flat line for Energy Consumption History" for the periods when Cruise Control is used...
Does it mean that the Electric car always consume "same energy when Cruise Control" is used, irrespective of Running Speed?
During cruise mode, you only need energy to overcome the frictional drag offered by air and friction due to tire rolling on ground. This energy is very less than accelerating a vehicle. Further modern cars are very aerodynamic, hence they have low drag resistance.
This drag also depends on vehicle speed you are going but as you would usually use cruise mode on relatively close speed values therfore it shows same line.
@@zia.g63 Let me rephrase the query
"Cruise at 40kph and Cruise at 90 kph.
Which one will be taking more charge (given that both have flat line)?"
@@rashmiRanjan20246 ofc the 90 kph will take more power and deplete your battery faster.
@@siontheodorus1501 Thanks, so the flat line on energy history is unreliable?
@@rashmiRanjan20246 if it just shows consumption history with only a line without any values or scale shown, i guess it is more to unusable instead of unreliable
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Tell me why we can't force motor to rotate in reverse direction in order to completely stop the car without friction braking
why would you waste more power?
@@DrDrift-rl6cc Won't it recharge the battery instead since we are consuming rotational kinetic energy of the wheel? Energy has to flow somewhere, right? (Btw Work done by torque is negative when angular displacement is in opposite direction, so motor 'should' act like a generator)
It's been a while since you reuploaded lol
Is this the same system that Toyota uses in the Prius and hybrid models?
Yes
Does it mean that in electric cars there is no functional analog to classic combusting car's „Neutral“ or clutch pedal pressed, when the car moves solely via it's own kinetic energy?
That's right, motor is always connected to wheel
@@beakmannHello, thanks for answering my question. Well, that seems pretty ineffective to me, as the motor either drives the wheels or is driven by the wheels and recuperates, which probably means quite substantial losses in the charging / power conversion train.
I use the Neutral gear all the time when driving my 1.7 CRTD diesel Opel Astra. That way it only consume about 4.2 l/100km.
@@medvidekkrupicka1404regen can be about 90% efficient. But yea, sometimes it sucks to be unable to roll
In some EVs there is.
You can turn off Regen entirely in some models.
I use this all the time in a Tesla . Would it wear out any component faster?
No
Yes, but I still don't understand, that how this supply the motor and regenerate power from the motor simultaneously?
It just flips from the motor spinning the tires with battery power, to the tires spinning the motor instead as your car is rolling.
The hard work of cranking the motor slows the tires down and the reversal also puts power into the battery.
4:00 I heard somewhere that it's between 20-60%, not 10%.
Is there a way to actively control regenerative braking torque? The problem with modern regenerative braking is that you have to try and estimate when to remove your foot from the accelerator pedal in order to minimize wasted energy. If you estimate the timing incorrectly, you'll need to use friction brakes at the end, which wastes energy.
Probably way less than 10%. Stopping from 60 MPH typically takes around 5 seconds. Let's be generous and say it takes 10 seconds. How much charge can be put into an electric car battery in 10 seconds? Not much. Even if the car is stopped 20 times from 60 MPH, that's still less than 200 seconds of charging time which won't increase range much at all.
@@dno8025 yep, there will always be waste heat in the end, cannot beat entropy
@@dno8025 That assumes all braking is as aggressive as you describe. In reality, you can often coast to maximize the regenerative braking energy captured
@@gabedarrett1301 - Using only regenerative braking it takes less than 10 seconds to get from 60 to 0 on many electric cars.
You can control Regen stopping power on the fly in some EVs.
It's in some menus in Teslas but right by the steering wheel with levers/paddles in some cars like the Ioniq 5.
I prefer the paddles, much more convenient when you need to change braking NOW
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This works for induction motors. What about the new tesla cars that use IPM-SynRM electric motors?
All electric motors are reversible with the right controls.
For emergency brake the reverse excited slow the motor fast then hydrolic add on stop tge cars but we must control current so no locking
Please explain RMF speed. What is RMF?
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Can we use generator to run electric car??
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Once you get used to it (like a week) it sux not having it.
Just dropped 3 bangers on us.
So this means you can't just lift your foot on a slope to save energy like on a normal car?
I think you would have to keep your foot on the accelerator pedal lightly but then the cars weight would pull the car down faster, meaning the RMF would be rotating faster than the motor so it would be charging it, if I am understanding this correctly. If you are fully off the throttle I think you will regren but still slow down. If you are light on the throttle I think you will regen and keep speed.
Can anyone confirm or correct me?
There are some EVs where you can adjust the amount of regen or turn it off completely
At what point is the system smart enough to know you are coasting to slow down/stop versus coasting to maintain speed? Ex: let off the gas because I see a stop sign up a head, great way to regain energy since I will be stopping regardless. But what if I just want to “coast” down a slight hill. I’m not gonna add gas, let gravity do the work, but it seems like in this system I’ll be pulling energy and therefor slowing down compared to a standard car. Then (as physics works/commute type scenario), I will need to at some point regain that height (energy) and there is always an efficiency loss somewhere. I’m asking now or in the future will we be able to optimize for true coasting conditions versus “taking your foot off the gas” conditions
You simply ease off the accelerator pedal, not take your foot off completely, and then it does what you would call coasting. It feels very simple and natural.
It's not all-or-nothing. You can ease off the accelerator in one-pedal steering, or in some vehicles use paddles by the steering wheel to "downshift" or "upshift" for different levels of regeneration and braking power.
So it has nothing to do with heat? I always thought it was heat that creates regenerative breaking. I always knew that dont make any sense. I was questioning how are turning the heat the break rotors makes into electric power to charge the batteries. Thanks for this video, now o know it a motor that is primary tool for the charging, now that make alot of sense to me
We could build in a steam boiler, but that would be a lot of extra parts.
Why on earth would I want my car to break if I let off the accelerator pedal? No one drives their car on the street or highway with the pedal always pressed.
Except that due to inefficiencies and friction and air resistance and a whole lot of other factors in well, all parts of the system, only a small portion of the energy used in going up a hill is returned to the battery. A very small portion indeed.
Check data. Driving down through mountains, a battery can recharge almost all the energy used going uphill.
@@FrunkensteinVonZipperneck Wrong . Completely wrong. What I said 2 months ago remains true. Very very little energy is recovered.
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I noticed that in the animation that showed the Tesla interior there was no fire extinguisher mounted within view. In this normal?
I have a Nissan from 1994 with manual transmission and diesel with mechanical pump (no electronics in the engine/gearbox). And I also have one-pedal driving in it, I apply brakes only for complete stop. So nothing special in braking when you release the gas pedal.
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One issue with regenerative braking is that the car slows down, but usually the rear brake lights don’t come on. So the driver behind you might not realize you’re slowing down.
My rear brake lights come on in my Model Y when I use regenerative braking.
Mine come on.
The first time I drove a Tesla, I thought the regen braking felt so weird. Now I can't drive without it and don't think I can go back to a car without this feature.
Doesn't regenerative braking cause more heat in an already HoT motor?
The motors don't run very hot at all.
@@logitech4873 It depends how fast & hard you run them. That is why over boost or "Pass" is only for a few seconds. Also braking generates tremendous heat, so much so even Carbon Composite rotors glow red on F1 & Indy cars. Can a motor really turn the friction from braking heat into electricity at the rate required in the time available?
@@kevinburke6743 "boost" or "pass"? Huh?
The motors absolutely don't run very hot. They are liquid cooled and shouldn't go above around 100-120°C.
When I drove around Nürburgring 3 times this summer in my Model 3 with regen set to full, the motors never got very hot. I had contact microphones mounted to one of the motors via plastic clips, and they stayed on all day.
Friction brakes convert almost all of the energy to heat.
Regenerative braking converts ~80% of the energy back to battery storage. The heat from this is easily managed by the cooling system.
@@logitech4873 Good to know, so why don't they put oversize or additional motors on EV's to do all the braking? Or is it legislation? A car (EV) without traditional brakes would be so much easier to maintain! No pads or rotors, no dual circuit hydraulics. A good chunk less unsprung mass! So it would be only steering and tyres that would be wear/replace when worn parts?
@@kevinburke6743 Modern EVs already do the vast majority of braking via regeneration. I almost never use the disc brakes on my Model 3.
However there are several good reasons to keep the physical brakes:
1 - Regeneration braking is never as strong as hydraulic brakes. You wouldn't be able to brake as fast in an emergency.
2 - When coming to a complete stop, normal brakes do a much better job at keeping the car stationary.
3 - When the battery is at 100%, regeneration will not work because the battery cannot take more charge.
4 - When the battery is very cold, regeneration will be much weaker because the battery cannot accept a very fast charge. (Battery needs to be 20°C+ for optimal regeneration)
5 - If your car malfunctions, it's important to have a mechanical backup for braking.
So for now it's best to keep both.
What to do when I want to coast.
Turn off Regen braking.
I think you can't do that in a Tesla but you can in some EVs.
Rethink your priorities.
only 10%?
seems low... anybody know why it's not so efficient?
I read somewhere that it's 20-60%
I don’t know if that number is accurate but keep in mind he’s talking about efficiency for driving overall. Regen can only recover energy when you’re slowing down. So if you’re just cruising on a highway for example, it’s not doing anything.
In terms of merely regen itself, ignoring total car efficiency, regen is about 85% efficient (in terms of converting your kinetic energy to electric). So the process is very efficient. It’s just that the majority of driving does not involve stopping, so the overall efficiency boost isn’t huge.
Increasing your range by 10% by recouping energy lost to unnecessary acceleration or banking energy on downhill runs is huge. If you over-accelerate and over-brake, and never change those habits despite the car telling you it's killing your range, then technically regenerative braking might be extending your range more than 10%, but your total range will still be less than if you were driving sensibly.
Why cant we just use the power of the wheels turning while u drive meani g the need for just initial charge surely thats possible y use brakes only reason i can think of is big oil companies??
Great video. But I have to wonder if you still having financial problems with the channel that you spoken of earlier.
I was very confused about which Tesla they were talking about until they specified “Tesla car” 4 times.
So there is still so much space before it's green energy and could power households but then again it would not benefit so much electric companies but it would save battery materials
This has been around for 75 years on locomotives. It's call dynamic braking.
01:03 *Lorentz force law
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Gotta love in some car models it does not put the brake lights on when regenerative braking is applied. Is a loophole in the law. If a car in front of you is at max regenerative braking it will be slowing down pretty significantly and there will be no brake lights to tell you. Brakes lights only have to be on when friction braking is applied. Till the loophole in the law is fixed you rear end one, ,brake light on or not, your fault.
This was the comment I was looking for.Bloody dangerous for the vehicles behind it.
@@mehmettemel8725Tesla puts brake lights on.
nonsense. in the USA, NHTSA requires (of all manufacturers) the activation of brake lights upon deceleration. additionally, there are laws against vehicles' brake light system not being functional.
I can’t believe with all the technology we have today, there are still people who think that the only way to have a functioning brake light is to tie it to the physical action of pressing a pedal…
The brake lights are tied to rate of deceleration, not to usage of a pedal or application of friction brakes.
Tata Nexon ev I love it regenerating system I am from India
Clever 😂
But wait, induction motors don't generate electricity when turned.
The process is much more complicated
OMG 😮
What's wrong with lesics, Why are they re-uploading?
Dark magic
0:10 Not only Tesla have this but almost every new car
Regenerative braking can fully stop the car these days without using the friction brakes
I'll venture a guess there's break blending like mentioned in the video which activates the break when you release the throttle.
@@SterorNo, you can actually stop the car completely with regen. It works best at lower speeds like around 40 mph and less, the lower the speed the stronger the regen is, but it does need practice to get the timing right so you can stop the car where you want it. An update added physical braking when regen isn’t at full capacity like when it’s cold or having a high battery SOC.
@@gabem8119 how do you know you're only using regen? My 2014 Tesla MS will regen break fine at high speed but at about 3-5 km/h the regen is so weak it becomes infeasible to use. Newer cars can do break blending so they use friction brakes when regen is not enough.
If you are sure that your car is not doing break blending and can stop from 10 km/h to 0 in under 3 seconds, I really want to know what car it is and why mine can't do that.
All the new Teslas 2020 and newer stop on their own very quickly. I owned a Chevy bolt that stopped on its own, no braking. My 2021 model y stops on its own, no breaking. There is a toggle in the car specifically for to be able to using breaking when regenerative breaking is not available, but it’s very clear the purpose of this is to function as normal when it is fully charged. For folks who have never experienced regenerative breaking, if your car is charged to 100%, the car will not activate regenerative braking. So, it will coast as it normally would, as if it is in neutral or how a gas powered car would coast.
Most electric cars nowadays will stop completely using only regenerative breaking. This video is extremely outdated.
It could in some situations, but would recoup less power by doing so. Your regenerative braking system cannot optimize energy capture if it needs to prioritize stopping the car. The two goals aren't perfectly aligned. Strategic use of the friction brakes actually allows regen braking to be more efficient.
Nice explanation, but it's a confusing nsme
American accent, British steering. Perhaps an Irish leprechaun made this video 👯
WMB product placement
🤔👍
I'd like to point out that one isn't slower than the other, but out of phase.
They should use this concept of regenerative braking in normal combustion based vehicles ...so that the battery used for headlights purpose can charge easily... Without replacing it... Btw great video
Alternator
Normal combustion engine already has alternator that takes some energy from the engine and converts it into electricity. Headlights are pretty low power so it isn't a big load, but for A/C that one requires big power especially when the compressor is on.
Lots of new gasoline cars in EU since 2020 are now mild-hybrids with 48 V battery charged during regen braking.
A normal car battery can’t handle the amount of power that regenerating creates. At peak regen can be pushing 80kW or more of power, depending on the car.
You need a separate high voltage battery to do this. Only hybrids and EVs can do it.
@0:06 this is obviously a car with the steering wheel on the wrong side........
Electric car have cooling system, then explain
Now i understand when the inverter fail to regenerative brake, you won't be able to brake too.
The mechanical brakes are still there, obviously. I have never heard about regenerative braking "failing" though. It's a very reliable system.
They need to turn on brake light so driver of older cars know that tesla driver is slowing or stopping
They do…brake lights are triggered by deceleration rate nowadays.
😉😍
*RMF = Rotating Magnetic Field*
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