Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

[NEWS] Under the skin: How Volkswagen's EV drivetrains get more from less

Under the skin: How Volkswagen's EV drivetrains get more from less

VW APP550 drivetrain
Volkswagen’s APP550 electric drivetrain is for next-gen ID cars

With more windings and redeveloped inverter, VW's EV developments draw parallels with ICE tuners

The view that an EV is no better than a glorified milk float with all the technical appeal of a washing machine is being put in its place.

As manufacturers begin to fine-tune EV motors and drivetrains to get improved range and performance, it becomes clear that the difference between electric and ICE may not be as great as many assume.

Volkswagen has just announced its new drivetrain for the MEB vehicle architecture with a systematic series of design tweaks aimed at getting more for less. Or to put it another way, finding more torque, more efficiency and better range while fitting into the same space. 

Intended for the next generation of the ID family, the new, rear-wheel-drive APP550 drivetrain generates 281bhp and 406lb ft of torque at the final drive, depending on the gear ratios in the single-speed reduction gearbox. 

Torque is affected by gearing so, for example, reducing the gear ratio multiplies the torque. It’s why in a conventional ICE car with a manual gearbox, it may be possible to spin the wheels in first gear but not in second. 

It’s also why you have to change down to climb hills. So VW’s quoted 406lb ft of torque is not to be confused with torque output from the motor shaft: it’s what is being sent to the driving wheels, having passed through the reduction gearbox. 

The increased all-round performance of the drivetrain was achieved in much the same way as it has been for over 100 years with combustion engines: by finding ways to extract more mechanical power from the same amount of energy. The difference is the energy is in electrical form and not heat from burning fuel, so how was it done?

VW uses permanent magnet synchronous motors that follow the tried and trusted approach of a solid rotor with embedded magnets, surrounded by the windings that generate the rotating magnetic fields. The magnets in the rotor slavishly follow the fields and so the rotor spins. It also keeps pace with the fields so its speed is synchronised with them, hence the term synchronous. 

The windings (collectively called the stator because it doesn’t move) have increased in number and the wire used has a larger cross section (it’s thicker). At the same time, the rotor has more powerful magnets and the drive system has been beefed up to withstand the much higher torque.

The inverter – the brain that converts electricity between DC (battery) and AC (motor) – has been redeveloped. It can handle higher current and the software has been improved so the motor converts electricity into mechanical energy more efficiently.

Instead of using a power-sapping electrical pump, the system self-cools by allowing the gear wheels and other components in the transmission to distribute the oil without one, and once heated, the oil is collected and cooled. 

So by scrutinising each part of the car’s ‘engine’ and drivetrain and making improvements, engineers have followed a similar approach to engine tuners of yore. Only the energy source has changed.

Forum Jump:

Users browsing this thread: 1 Guest(s)