2019

#zfexperts

The Ideal Electric Motor for any Need

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Dr. Matthias Beringer, January 31, 2019
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Dr. Matthias Beringer is a Group leader in the Electric Traction Drives Business Unit. He and his team are helping to develop electric drives, especially at the start phase.
The electric motor was invented well over a 100 years ago. It is simpler in design and constructed using far fewer parts than a combustion engine. Its efficiency nowadays is, at its best, over 97%. When it comes to energy yield, it exceeds gasoline engines by almost 30 percent and diesel vehicles by around 40 percent, which is considerable. Nevertheless, we find and leverage many opportunities to make electric motors even better. For example, with the aid of computer simulations, we create the best possible electric motors for various customer and operating requirements.

At the beginning of a project, basic technical questions have to be answered: What technologies should be used? What are the customer’s general requirements? How should the stationary part of the engine (stator) interact with the rotating part (rotor)? Should the rotor follow the magnetic field of the stator (asynchronously) or move with it (synchronously)?
This also depends on how the rotor is designed. For permanent magnet rotors in a synchronous motor, the material itself generates the necessary magnetism, thus ensuring a high level of efficiency. In contrast, for a rotor in an asynchronous motor, the magnetic field has to be generated by electricity. Which is better?
These days, for passenger car applications, we usually prefer the 3-phase permanent magnet synchronous motors. However we are also able to rely on a broad technical portfolio of other machine topologies.

Other differences include the construction of the rotor and the winding technology in the stator, in other words, how the electric conductor is wound to a coil. The so-called “hair pin technology” offers benefits in terms of performance and efficiency in this respect. The name comes from the shape and special bend in a square copper wire that looks like a hair pin. Other technologies, such as shaft winding, also benefit from inserting a rectangular wire in the stator grooves.

Well-designed from start to finish

Well-designed from start to finish

ZF is naturally not the only company that knows how to produce an electric motor. The company’s special ability is that it takes into account, right from the start, all the other factors involved in motor development, including especially power electronics, cooling systems as well as the transmission, particularly in the case of hybrid drives. But in terms of the system as a whole, we also optimize our motors on an ongoing basis regarding service life, robustness, installation space, noise behavior as well as the use of materials and costs. Last but not least, in the later production of ZF products, we guarantee reproducibility: All motors of one type always have the same high quality and therefore identical properties in practice.

Outstanding from every angle

Outstanding from every angle

Our claim and expertise to produce the best electric motor for each of our customers’ specific applications is noticeable to everyone in plug-in hybrids or electric cars. ZF electric motors demonstrate outstanding performance and range simultaneously while also spoiling with excellent acoustics. Not only that, there is no start-up whining or annoying sound at certain speeds. And it gets even better: With increasing improvements in simulation tools, the newest findings from ZF research, material science and thermal concepts as well as a wealth of experience in the company, we will be able to get even more out of the electric motor. Our superb positioning in the market is also reflected in our continual analysis of key performance figures which we use to track our performance compared to other market players and to create challenges for ourselves daily. We are already extremely well set up for our next major project: 800 Volt electric motors which are becoming possible thanks to new power electronics (silicon carbide) and battery technologies.