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Neue Klasse additionally incorporates ASM technology
The Gen6 powertrain employs a second, additional electric motor technology in the form of the asynchronous motor (ASM). Here, 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.
Extensive improvements to EESM technology
Besides the addition of ASM technology, the EESM technology has also undergone a major upgrade for Gen6: rotor, stator and inverter have all been fully designed for the new 800V architecture of the Gen6 tech in order to maximise drive system performance and efficiency. This has been further helped by a complete redesign of the oil and water cooling systems. In addition to this, the experts from the BMW Group have also succeeded in improving the electric motor and central housing in terms of their weight and rigidity too. The transmission still uses a two-stage helical design, but has been further optimised by enhancements to its geometry and cooling, lower friction levels and more pleasant acoustics. The electrically excited synchronous motor’s “brain”, the inverter, now features 800V technology along with silicon carbide (SiC) semiconductors to boost efficiency. The inverter is completely integrated into the electric motor’s housing. Its task is to convert the DC power supply from the high-voltage battery to AC for use in the electric motor. The inverter was developed in-house by the BMW Group and is produced at Plant Steyr in Austria.
Lower weight, costs and energy losses – greater efficiency in the vehicle
The results obtained from intelligently incorporating new technologies into the electric powertrain while consistently enhancing existing systems make impressive reading. When compared to a Gen5 xDrive model, a future Neue Klasse model complete with EESM and ASM technology boasts the following improvements: energy losses have been reduced by 40%, costs by 20% and weight by 10%. By combining different types of electric motor, the BMW Group’s technology-open approach is therefore clearly in evidence within the field of electric mobility. In 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. The sixth generation BMW eDrive technology is a significant factor in the gain in overall vehicle efficiency of around 20 per cent for the Neue Klasse. This figure is based on a comparison with the current generation of all-electric vehicles from the BMW Group.
Thermal management: complex interaction, crucial for performance
Thermal management involves highly complex interaction between various systems in an electric vehicle and is of critical importance for a host of performance parameters, including range, real-world consumption, acceleration and charging time. Thermal management is a question of constantly keeping the temperature of the electric motor, power electronics and high-voltage battery in the optimum range, while maintaining standards of passenger comfort at the same time. Efficient thermal management is important for fast charging too. Here, the battery temperature must be kept within a defined window in order to make optimum use of the available charging capacity. Unlike combustion engines, electric motors give off little heat. This means that, depending on the operating state, the battery and the passenger cell have to be not only cooled, but heated too. The Steyr site develops the thermal management systems for all electric vehicles from the BMW Group. The plant’s development centre is also responsible for the brain at the heart of the electric motor – the inverter.
Highly intelligent central control unit: the BMW Energy Master
All of the elements that enable this technological leap forward come together in the BMW Energy Master. This central control unit is positioned on the high-voltage battery and provides the interface for high- and low-voltage power supply and for data from the high-voltage battery. It also controls the power supply for the electric motor and vehicle electrical system and ensures the safe and intelligent operation of the high-voltage battery. The BMW Group has filed a whole series of new patent applications for the vehicle electrical system, including its electronic fuses. Both the hardware and software of the Energy Master were developed fully in-house at the BMW Group. This ensures technological developments and updates for vehicles can be implemented independently and in real time via Remote Software Upgrades, providing a particular benefit for customers.