As it turns out, Munro & Associates has received the drive unit of the car from Volkswagen for review, after - and despite - the criticism of the car by Sandy Munro. An interesting move from the German manufacturer. The team is currently working on a teardown of ID.4's battery pack.
The electric motor episode turns out to be very informative and technical, so let's get into details.
The Munro Live Team disassembles and analyzes Volkswagen ID.4's rear electric drive unit, which consist an electric motor, single-speed transmission (gearbox) and inverter.
In the future, Volkswagen ID.4 and other models will get also a front electric motor for dual-motor all-wheel drive.
It's a standard drive unit that Volkswagen produces in-house and uses in multiple MEB models, including ID.3. The Volkswagen Group Components makes those units in the Kassel plant in Germany (some components come from other plants).
The rear motor is described as a permanent magnet brushless machine and it's rated at 150 kW and 310 Nm. The gearbox is just a single-speed reduction.
Sandy Munro notes that the entire unit has common mounting points to use in various vehicles, which is a different approach than in the case of Tesla, which adapts to particular cars, eventually two similar models, like Model 3/Model Y.
APP 310 electric drive for modular electric drive matrix (MEB):
- 150 kW (200 PS) of peak power
- 310 Nm of peak torque
- maximum electric motor speed of 16,000 rpm
- a permanent magnet brushless machine
- rear drive unit
- single-speed gearbox (10x reduction of transmission ratio using a two-stage design)
- for MEB-based EVs
The review starts with the single-speed transmission with tight tolerances that turned out to be very interesting, as it has only three small bearings, instead of usually four. According to Sandy Munro, it should reduce friction and he expects that other manufacturers will follow.
Sandy Munro praised Volkswagen's solution, although he found some burrs inside. The manufacturer was worried to hear about that and probably will have to double-check it.
Another thing is the cooling system of the drive unit. It's also very interesting, as it starts in the inverter (compact power electronics usually has the highest requirement for cooling) and goes a few times through the motor to the gearbox.
Sandy Munro notes that Volkswagen has eliminated an cooling pump, an oil filter, and a heat exchanger which Tesla still has.
Another interesting thing is the stator of the electric motor. It has a hairpin design at the ends, that increases density of copper in slots from 46% to 60% compared to round wires, which means higher current and higher magnetic field.
The hairpin design is not a new thing and it's interesting that Tesla sticks with round wires.
The laminated rotor has its own combination of permanent magnets and four segments to reduce the noise, vibration, and harshness.
It's difficult to say anything about the motor without in-depth tests, however, Sandy Munro notes some better ideas than long bolts to keep the rotor a single piece.
The last part is about the inverter, but again - only a brief review of the layout - everything looks very good inside, aside from the tsunami of bolts and maybe a better solution to a bleeder resistor (the current is not bad).
Overall, Sandy Munro was very positive about the Volkswagen ID.4's rear-drive unit, which is interesting, compared to cold reviews of the ID.4 in the previous episodes.
More about Volkswagen ID.4