By ATN Editorial Team
The BMW Group is presenting its next leap forward in the field of electric drive technology – and in the process ushering in a new era of all-electric driving. At the Tech Days event in Landshut, the company has provided some initial insights into the development and production of high-voltage batteries and electric drive systems using the sixth-generation of BMW eDrive technology. Every fully electric Neue Klasse vehicle will enjoy the benefits. The first Neue Klasse model will go into series production later this year at Plant Debrecen in Hungary. Below is an overview of the technology highlights:
- The Energy Master intelligent central control unit on the high-voltage battery – developed by the BMW Group and produced at Plant Landshut.
- A new high-voltage battery concept that, together with the BMW cylindrical cell, promises to bring about a technological quantum leap – including significant improvements in energy density, charging speed and range.
- The BMW Group also demonstrates its technology-openness with electric drive systems – through the use of different electric motor types: SSM and ASM.
- A modular approach to electric motor production gives the BMW Group an exceptional degree of flexibility.
- The BMW Group pools together expertise from the entire electric mobility value chain in Bavaria and Austria – from development, via purchasing and production, to recycling.
- The BMW Group demonstrates both technology-openness and full expertise across all areas of electric mobility.
Adopting a technology-open approach while setting the pace in electric mobility
“For the BMW Group, electric mobility is the future and a key area of growth. We are leading the way with this drivetrain technology. At the same time, we are deliberately taking a technology-open approach, recognizing that mobility needs vary between different regions of the world,” explains Dr Joachim Post, Member of the Board of Management of BMW AG, Purchasing and Supplier Network. “We want to offer our customers the best drive concept for every need. It is possible to do both: offer the best drive technology for every need and be at the forefront of electric mobility.”
Slimmer, faster, further: the high-voltage batteries for Gen6
With the new sixth-generation BMW eDrive technology (Gen6 for short), the BMW Group is making a technological quantum leap. Improvements on the product side include a 30% faster charging speed and 30% increase in range, with certain models achieving even higher figures. Added to which, the Gen6 high-voltage battery concept benefits from the new 800V technology. Gen6 will make its debut this year in the Neue Klasse and subsequently be used to drive models across the BMW Group’s fully electric product range. The concept for the Gen6 high-voltage batteries is fundamentally new and will find applications in all vehicle segments – right up to the high-performance models from BMW M GmbH. Its new, even slimmer design allows the high-voltage battery to be integrated into a spread of different models, regardless of vehicle height. The high-voltage battery takes on the role of a structural component in the bodies of the Neue Klasse models (“pack-to-open-body”), and the new cylindrical cells will be integrated directly into the high-voltage battery (“cell-to-pack”). The new BMW cylindrical cell has a 20% greater energy density than its predecessor, the Gen5 prismatic battery cell. And charging in both directions will be possible: the BMW Group has confirmed bidirectional charging as standard for Gen6.
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.
“Cell-to-pack” and “pack-to-open-body”
Production of the Gen6 high-voltage batteries follows the “cell-to-pack” and “pack-to-open-body” principles. “Cell-to-pack” involves positioning the cylindrical cells – manufactured by the suppliers according to BMW Group specifications – directly in the housing of the high-voltage battery, without the intermediate step of a module being produced. “Pack-to-open-body” refers to the high-voltage battery’s new role as a structural component in the vehicle architecture. Numerous innovations patented by the BMW Group can be found here.
Technology-open approach for electric mobility: the new e-drive system of Gen6
The BMW Group has retained the principle of an electrically excited synchronous motor (EESM) for its Gen6 power unit. On this type of synchronous motor, the magnetic field in the rotor is generated by windings fed with direct current rather than permanent magnets. In this way, the strength of the rotor’s magnetic field can be optimally adjusted to the prevailing load conditions. This results in both excellent levels of efficiency at customer-relevant operating points 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. Many of the motor’s technical details were created with the help of patented expertise, with the non-potted rotor alone accounting for more than ten patent applications.
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 electric drive technology 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.
Modular concept provides crucial advantage for manufacturing electric motors
The manufacturing concept for the Gen6 electric drive system uses the principle of modular building blocks. 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. 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.
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.
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