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Copper wires and magnetic fields - how an electric drive is made

25.11.2019
Copper wires and magnetic fields - how an electric drive is made

It’s compact enough to fit in a sports bag, only weighs 90 kg but generates more than 200 HP - features of the electric drive in the new Volkswagen ID.3.

The Volkswagen ID.3 heralds the beginning of a new era. Designed on the MEB platform, a modular architecture developed specifically for electric vehicles on which many new models across various Volkswagen Group brands will be based, the car has the potential to “push” the spread of e-mobility.

The two fundamental components in an electric car are the battery and the drive. From a technical perspective, the latter is not only less complex than a conventional petrol or diesel engine, but also compact enough to fit in a sports bag. But how does it actually work?

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Stator and rotor

The main elements of an electric motor are the stator and the rotor. The stator is a stationary component - a sort of hollow cylinder made of copper wire coils. The rotor, on the other hand, is a solid cylinder that begins to spin when an electric current flows through the stator and a magnetic field is created. The rotational movement is based on a very simple physical principle: opposite poles in a magnet attract each other, whereas similar poles repel.

Synchronous and asynchronous

There are two types of electric drive: synchronous permanent magnet brushless machines and asynchronous machines. The first type features a permanent magnet rotor, which rotates in sync with the magnetic field of the stator. In asynchronous machines, however, the rotor uses the electric current to generate its own magnetic field and, as a result, the rotation of the rotor lags behind the stator’s magnetic field rotation.

The ID.3 motor

The Volkswagen ID.3 is fitted with an APP 310 electric drive, a permanent magnet brushless machine. The “APP” designation means that the drive and the gearbox are in parallel with the axle, whilst the numerical sequence derives from the maximum torque of 310 Nm.

The main components for this drive are produced using specialist suppliers and manufacturing at various Volkswagen Group Components production sites.

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Maximum efficiency

The rotor and stator, for example, are produced at Salzgitter. Hairpin technology has enabled the use of an innovative production process whereby the spaces within the laminated core of the stator are optimally filled with flat preformed copper coils.

This increases the torque density and the efficiency of the electric drive compared to drives with wound copper wire coils. Maximum torque is achieved even at a low engine speed, which means that a 1-speed gearbox is sufficient. Both the electric drive and the gearbox are produced at the component plant in Kassel. The drive unit weighs around 90 kg, generates 150 kW (204 HP) and is compact enough to fit in a sports bag.

The role of Kassel

In the future, the electric drives for MEB vehicles for Europe and North America will be produced in Kassel. Production of 500,000 units per year is the target. Kassel also works closely with the plant in Tianjin, which is the manufacturing base for the Chinese market.

Together, the two plants will produce up to 1.4 million electric drives a year from 2023, making Volkswagen Group Components one of the largest global manufacturers.

SourceVolkswagen AG

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