@11:00 The brushes supply electricity to the rotor this creates a magnetic field that interacts with the stator causing rotation, this is not required for a permanent magnet (PM) motor, as obviously the magnetic field is already present. I would imagine there is a rotary encoder/resolver on the other end of the shaft?
Those brushes will be for supplying power to the rotor in order to create a magnetic field for the motor to function. This is similar to the arrangement in a car alternator - the slip rings and brushes are hidden under the plastic end cover and the brushes usually last 100k to 150k miles whereas the slip rings can last twice that. In the motor the brushes and the slip rings will eventually wear out so I am surprised that both are not made more accessible in the design of the motor casing.
Yep. 100% right. There are no permanent magnets, so they make a magnet using a coil of wire. Feed current through it and hey presto, you have a magnet that can spin. Create a rotating magnetic field using the stationary coils of wire and the motor spins.
Great video, very interesting as last year my gear selector switch failed on my ZE40 and I was without my car for nearly two weeks waiting for a switch.
There is something like a 12:1 reduction ratio between the motor rotor and the drive wheels, so those 4 (90deg spacing) park pawl dogs actually result in locking the drive wheels 48 times per rev, ie every 7.5 degrees more than good enough to find an engagement point. And of course, that 12:1 ratio also means the drive wheel locking torque is reduced by 12 times, hence the relatively small size of Pawl required to hold the car under all circumstances (there are specific homologation / cert tests for parking brake performance as well as that carried out on our normal MOT test) Most newer EDU's use a small electric motor to activate the parking lock, that way they can do away with the old style shifter, the cable required to link the EDU to the that shifter, and the build step required to connect and set it all up during the manufacturing process which is significantly costs and complexity addition.
The brushes with slip rings provide an electrically-excited rotor which avoids the need for rare earth rotor magnets in the "PM" motors that most EV makers use. There is nothing old-fashioned about this, it's just an alternative, noting that it also provides the option to turn off the rotor field to reduce losses while coasting, the same reason why Tesla use an induction motor at one end in AWD variants. The Nissan Ariya and newer BMW models also use an electrically-excited rotor. As for the problems experienced, I'd not be surprised if conductive dust from the sintered bronze brush material is settling on interior HV connections and that slight conductivity could be causing the loss of electrical isolation error. On to the gear reducer. There's nothing really wrong with the non-serviceable particle retention magnet installed and you'll note that it's well-secured unlike the Ioniq and gen-1 Kona/Niro. Many other gear reducers, manual gearboxes and automatic transmissions have similar. The first I've seen myself was in a mid-1950s 3-speed Saginaw (Chevy) manual gearbox, so it's not a new idea. There should be enough particle capacity for the lifetime of the car. You can see that it does hold particles unlike the Hyundai/Kia models mentioned, those reducers which also happen to be abnormally prone to failure. Although a magnetic drain plug would be a good alternative, I'd be slightly wary of the location in this case as the oil turbulence is high so close to the final drive. They've placed the fixed magnet in a quiet corner. Looking forward to a complete teardown of the motor, in particular noting how the motor bearings have a fixed and floating end. That's been another failure point of earlier H/K motors.
Exactly so. A great advantage of a electrically-excited rotor over a PM rotor is that you can regulate the magnetic field and adapt the motor for a wider rpm range. At low-rpm and high torque the rotor needs a strong magnetic-rotor, but as an electric motor speed increases a stronger rotormagnet will have more magnetic (stator) losses and the increasing back-EMF voltage will limit the max RPM. So magnetic losses, back-EMF and max-rpm can be greatly improved if you can change (limit) the rotors magnetic field as speed increases. You should also be able to get more regen out of a motor down to a lower speed when you can control the magnetic field of the rotor. Most EVs have just one gear ratio and an overly powerful electric motor in order to have enough wheel-torque at start and enough torque left at top-speed. By adding control over the rotors magnetic field you get the same effect as adding a constant variable gear transmission to the motor.
Great video Matt. When I hear people say there’s nothing to go wrong on an EV, I don’t buy it. I’ve seen quite a few videos recently that suggests otherwise. Love your videos though 👍🏼
Plenty can go wrong with ICE too. MY good lady just got a bill for £500+ after having her 70 reg Fiesta serviced, and two new rear shock absorbers fitted, after one began leaking oil....
@@Brian-om2hh Of course, but no one says things don’t go wrong with ICE cars. But tonnes of EV drivers/owners always claim there’s nothing to go wrong with EVs and I just don’t think that’s accurate
@@AndyC2_I don't think anyone who knows about cars and EVs says that. You can say there is less to go wrong with an EV. They don't have a fuel system or an exhaust system, they only have a modest cooling system and their electrical system is basically solid state (mechanical brushes aside). They also wear out brakes a lot less. And they don't have an engine with hundreds of components - they instead have a motor which we know are thousands of times more reliable. However they still have lights, suspension systems, cooling systems (although they don't operate at the same temps as ICE a failure can be just as catastrophic), bearings and in addition to ICE they have an HV electrical system. Still safe to say there are a lot less things to service and go wrong on an EV.
the contacts on the removable plates probably arent for just for sensing, i think it's also linked to some sort of safety power lock-out: The high voltage electricals are accessible when removed, and it's overall safer to cut power to avoid damage and harm to equipment and operators
There is a sort of sensor that senses if there is current leaks in the system. (somewhat similar to a earth fault breaker at your home) And when the brushes wear they emits dust that is conductive, that triggers the sensor to believe there´s a fault and the "Check Electric warning comes on. If you keep driving the car stops completely. Just open and clean everything in there and you´re good to go.
I can't believe it has brushes. I'm sure you could get similar efficiencies with an ac induction motor with the right software. I don't think it would cost more either. Brushes are very lossy, probably why they wear out so quickly.
Hi Matt Is the Gear Oil change or topup in the service schedule of the Renault Zoe ? Gary over at the RUclips channel: Gary C EV Repairs might find a use for the Motor.
No. The gear oil is not part of the service schedule as the manufacturers (in all cases) consider the reduction gearbox as "sealed for life". Its a good idea to change the oil every ~50k miles though. Its so cheap and easy to do, why not? The motor is stripped down to bits now - part 2 video coming soon.
I would have loved to chuck some power at that thing to see if we could get it to run. Simple enough stuff. Just a variable frequency and variable current supply. Not rocket science at all.
Unfortunately, Renault has not stopped using carbon brush motors in its new car models. And even presents it as a benefit of saving money on magnets. Personally, I wouldn't want a car with a carbon brush motor.
@@krisvandermeulen253 I can't find out what type of motor it has myself but the line you're looking for in a spec sheet is if it has a 'permanent magnet' motor. with any luck they've figured out that changing the brushes is going to cost them a fortune and decided against it.
@@krisvandermeulen253 Dacia Spring is practically a car from another manufacturer Dongfeng. Like perhaps all electric cars made in China, it has a permanent magnet motor, so no carbon brush.
Part 2 video coming in a few weeks where I attempt to strip the motor further and remove the bearings.
Where is the Part2?
@11:00 The brushes supply electricity to the rotor this creates a magnetic field that interacts with the stator causing rotation, this is not required for a permanent magnet (PM) motor, as obviously the magnetic field is already present. I would imagine there is a rotary encoder/resolver on the other end of the shaft?
Those brushes will be for supplying power to the rotor in order to create a magnetic field for the motor to function. This is similar to the arrangement in a car alternator - the slip rings and brushes are hidden under the plastic end cover and the brushes usually last 100k to 150k miles whereas the slip rings can last twice that. In the motor the brushes and the slip rings will eventually wear out so I am surprised that both are not made more accessible in the design of the motor casing.
Yep. 100% right.
There are no permanent magnets, so they make a magnet using a coil of wire. Feed current through it and hey presto, you have a magnet that can spin.
Create a rotating magnetic field using the stationary coils of wire and the motor spins.
Or more importantly... the bearings for the shaft!
Great video, very interesting as last year my gear selector switch failed on my ZE40 and I was without my car for nearly two weeks waiting for a switch.
There is something like a 12:1 reduction ratio between the motor rotor and the drive wheels, so those 4 (90deg spacing) park pawl dogs actually result in locking the drive wheels 48 times per rev, ie every 7.5 degrees more than good enough to find an engagement point. And of course, that 12:1 ratio also means the drive wheel locking torque is reduced by 12 times, hence the relatively small size of Pawl required to hold the car under all circumstances (there are specific homologation / cert tests for parking brake performance as well as that carried out on our normal MOT test)
Most newer EDU's use a small electric motor to activate the parking lock, that way they can do away with the old style shifter, the cable required to link the EDU to the that shifter, and the build step required to connect and set it all up during the manufacturing process which is significantly costs and complexity addition.
That was very interesting, thanks for sharing! Enjoy learning about this new tech
Glad you found it interesting.
The brushes with slip rings provide an electrically-excited rotor which avoids the need for rare earth rotor magnets in the "PM" motors that most EV makers use. There is nothing old-fashioned about this, it's just an alternative, noting that it also provides the option to turn off the rotor field to reduce losses while coasting, the same reason why Tesla use an induction motor at one end in AWD variants. The Nissan Ariya and newer BMW models also use an electrically-excited rotor. As for the problems experienced, I'd not be surprised if conductive dust from the sintered bronze brush material is settling on interior HV connections and that slight conductivity could be causing the loss of electrical isolation error.
On to the gear reducer. There's nothing really wrong with the non-serviceable particle retention magnet installed and you'll note that it's well-secured unlike the Ioniq and gen-1 Kona/Niro. Many other gear reducers, manual gearboxes and automatic transmissions have similar. The first I've seen myself was in a mid-1950s 3-speed Saginaw (Chevy) manual gearbox, so it's not a new idea. There should be enough particle capacity for the lifetime of the car. You can see that it does hold particles unlike the Hyundai/Kia models mentioned, those reducers which also happen to be abnormally prone to failure. Although a magnetic drain plug would be a good alternative, I'd be slightly wary of the location in this case as the oil turbulence is high so close to the final drive. They've placed the fixed magnet in a quiet corner.
Looking forward to a complete teardown of the motor, in particular noting how the motor bearings have a fixed and floating end. That's been another failure point of earlier H/K motors.
Exactly so. A great advantage of a electrically-excited rotor over a PM rotor is that you can regulate the magnetic field and adapt the motor for a wider rpm range. At low-rpm and high torque the rotor needs a strong magnetic-rotor, but as an electric motor speed increases a stronger rotormagnet will have more magnetic (stator) losses and the increasing back-EMF voltage will limit the max RPM. So magnetic losses, back-EMF and max-rpm can be greatly improved if you can change (limit) the rotors magnetic field as speed increases. You should also be able to get more regen out of a motor down to a lower speed when you can control the magnetic field of the rotor.
Most EVs have just one gear ratio and an overly powerful electric motor in order to have enough wheel-torque at start and enough torque left at top-speed. By adding control over the rotors magnetic field you get the same effect as adding a constant variable gear transmission to the motor.
Great video Matt.
When I hear people say there’s nothing to go wrong on an EV, I don’t buy it.
I’ve seen quite a few videos recently that suggests otherwise.
Love your videos though 👍🏼
Plenty can go wrong with ICE too. MY good lady just got a bill for £500+ after having her 70 reg Fiesta serviced, and two new rear shock absorbers fitted, after one began leaking oil....
@@Brian-om2hh Of course, but no one says things don’t go wrong with ICE cars.
But tonnes of EV drivers/owners always claim there’s nothing to go wrong with EVs and I just don’t think that’s accurate
Not nothing, but certainly much less.
@@AndyC2_I don't think anyone who knows about cars and EVs says that. You can say there is less to go wrong with an EV. They don't have a fuel system or an exhaust system, they only have a modest cooling system and their electrical system is basically solid state (mechanical brushes aside). They also wear out brakes a lot less. And they don't have an engine with hundreds of components - they instead have a motor which we know are thousands of times more reliable. However they still have lights, suspension systems, cooling systems (although they don't operate at the same temps as ICE a failure can be just as catastrophic), bearings and in addition to ICE they have an HV electrical system. Still safe to say there are a lot less things to service and go wrong on an EV.
@@mondotv4216 It’s an opinion that a lot of EV owners and sellers push, but most people see right through it
Interesting video Matt. Thanks for sharing. 😊
My pleasure
the contacts on the removable plates probably arent for just for sensing, i think it's also linked to some sort of safety power lock-out: The high voltage electricals are accessible when removed, and it's overall safer to cut power to avoid damage and harm to equipment and operators
Excellent, many thanks. Please could do a video on changing the gear oil in a Zoe?
Yes that is coming.
+1
There is a sort of sensor that senses if there is current leaks in the system. (somewhat similar to a earth fault breaker at your home)
And when the brushes wear they emits dust that is conductive, that triggers the sensor to believe there´s a fault and the "Check Electric warning comes on. If you keep driving the car stops completely.
Just open and clean everything in there and you´re good to go.
13m50s I reckon those two smaller cables (green & yellow) are for the sensor plate?
Yes you're right. I realised this too after I had edited the video.
Why not approach Cleevley to see if they'll purchase it for spares
The motor is in bits now - part 2 video coming in a few weeks.
I can't believe it has brushes. I'm sure you could get similar efficiencies with an ac induction motor with the right software. I don't think it would cost more either. Brushes are very lossy, probably why they wear out so quickly.
not gona lie was looking forward to seeing the motor 😓
Part 2 video coming soon.
Me to yay he's stripping it down :)
10:00
Brushes are made out of graphite, and it wears out. So graphite dust accumulates. All you habe to do is to blow it out.
Hi Matt
Is the Gear Oil change or topup in the service schedule of the Renault Zoe ?
Gary over at the RUclips channel: Gary C EV Repairs
might find a use for the Motor.
No. The gear oil is not part of the service schedule as the manufacturers (in all cases) consider the reduction gearbox as "sealed for life". Its a good idea to change the oil every ~50k miles though. Its so cheap and easy to do, why not?
The motor is stripped down to bits now - part 2 video coming soon.
This is my 10 years motor, 80k km
Not a differcult motor to repair.I am sure most motor electrical rewind shop could handle this including providing new motor bearing .
plz open the engine if you can! I don't know anyone to have done so. THANK YOU.
That's coming up in part 2 in a few weeks time
I would have loved to chuck some power at that thing to see if we could get it to run.
Simple enough stuff.
Just a variable frequency and variable current supply. Not rocket science at all.
Unfortunately, Renault has not stopped using carbon brush motors in its new car models. And even presents it as a benefit of saving money on magnets. Personally, I wouldn't want a car with a carbon brush motor.
I feel the same way, as soon as i saw the brushes i nodded my head in disapointment. looks like i've learnt never to buy a renault electric.
We just bought a Dacia Spring... I wonder if that model also has these brushes...
@@krisvandermeulen253 I can't find out what type of motor it has myself but the line you're looking for in a spec sheet is if it has a 'permanent magnet' motor. with any luck they've figured out that changing the brushes is going to cost them a fortune and decided against it.
@@krisvandermeulen253 Dacia Spring is practically a car from another manufacturer Dongfeng. Like perhaps all electric cars made in China, it has a permanent magnet motor, so no carbon brush.
I'm surprised they are not using a brushless motor - antiquated design. Even my lawn mower uses a brushless motor.
GBP 700 for two sixpenny carbon brushes! Oh dear oh dear 😂
What Renault's motors are not brushless and their battery garanties are shit!!! Why buy?