BMW Unveils New E-Drive System
Photo courtesy BMW AG
MUNICH—BMW AG recently unveiled the sixth generation (Gen6) of its eDrive technology, which will be used in its Neue Klasse electric vehicles. The heart of the system is an electrically excited synchronous motor (EESM).
The magnetic field in the rotor is generated by windings fed with direct current rather than permanent magnets. The strength of the rotor’s magnetic field can be optimally adjusted to the prevailing load conditions. This results in high levels of efficiency and constant power output at high rotational speeds.
As with the Gen5 version, the synchronous motor will be positioned above the rear axle and feature a compact housing incorporating the electric drive unit, power electronics and transmission.
The Gen6 power train employs a second, additional electric motor technology in the form of the asynchronous motor (ASM). Instead of being generated by permanent magnets (PSM) or electrical excitation (EESM), the rotor’s magnetic field is induced by the stator.
On this type of motor, the rotor takes the form of a metal cage. The asynchronous motor offers the advantage of a more compact design and superior cost efficiency. The ASM motor variants will be fitted at the front axle of Neue Klasse cars with BMW xDrive.
“When compared to a Gen5 xDrive model, a future Neue Klasse model complete with EESM and ASM technology boasts the following improvements: energy losses [are] reduced by 40 percent, costs by 20 percent and weight by 10 percent,” says Joachim Post, Ph.D., member of the BMW board of management responsible for purchasing and supplier relations.
“In the future, customers will be able to choose from models equipped with one, two, three or four electric motors to suit their individual preferences and requirements,” explains Post. “The sixth-generation eDrive technology is a significant factor in the gain in overall vehicle efficiency of around 20 percent for the Neue Klasse.”
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The e-motors will be assembled at BMW’s sate-of-the-art power train plant in Steyr, Austria, starting this summer.
“The manufacturing concept for the Gen6 electric drive system uses the principle of modular building blocks,” says Post. “This forms the basis for highly flexible manufacturing of various electric drive variants across the entire Neue Klasse model range.
“The modular building block concept leads to positive economies of scale, and cost savings in development and production,” claims Post. “It also has the effect of improving the scalability of production volumes. The modular approach ensures a high degree of flexibility in production, the supply networks and procurement.”
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