The puzzles for the best electric motors solved

The puzzles for the best electric motors solved

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There are electric vehicle motors with the latest technology, maximum efficiency, top performance or good price-performance ratio. And those that can be produced quickly in varying quantities. Electric motors "made by ZF" provide all of the above.
Achim Neuwirth,
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Achim Neuwirth has been writing for ZF since 2011. He has specialized in writing texts about all kinds of car-related topics: from vehicles to the technology behind them, to driving and traffic.
Electric mobility is booming, with more and more suppliers worldwide looking to get a slice of the pie. Many new manufacturers are venturing into the electric motor segment, with its supposedly simple products. Yet add automotive customer requirements into the mix and things quickly get complicated. Production requirements across various continents must be met, the fluctuating call-off figures need to be considered. Primarily, the motor must fulfill all the particular OEM specifications to the letter. Ideally, even surpass them. ZF's electric motors do just that, making them stand out from the competition.

How can you tell which is better? The electric motor is all about power and torque density, efficiency and quality. And ensuring the motor performs well all the time, not just in certain situations. "The electric motors from ZF set the benchmark in the decisive criteria," says Alexander Gehring, ZF Head of Development for electric motors. "Differences are more than just technical data. Drivers also notice these differences on the road." With that he is referring, among other things, to the ZF motor that debuted at the rear of the new Mercedes-Benz EQA.
"The electric motors from ZF set the benchmark in the decisive criteria."
Alexander Gehring, ZF Head of Development for Electric Motors

E-motor expertise meets system expertise

E-motor expertise meets system expertise
As an e-motor supplier, ZF is currently involved in around 50 different projects for about a dozen automotive manufacturers, including premium and volume manufacturers. The ZF Modular eDrive Kit, a modular kit for the entire electric drive including power electronics and transmission, also features electric motors. This system expertise has evolved over decades, allowing ZF to focus consistently on the big picture when developing individual components and fulfilling the associated orders. Vehicle manufacturers exploit this to their advantage: "We tend to be more than just a supplier also in projects where we supply only the electric motor as a drive component. Customers appreciate our consulting know-how when it comes to optimally designing an e-motor for the vehicle system," says Gehring.

Powerful modular kit meets all electric motor requirements

Powerful modular kit meets all electric motor requirements
What is important here is that there isn't one ZF electric motor for all applications. Rather, ZF can produce almost any automotive electric motor. Starting with the permanent-magnet synchronous motor (PSM), the solution of choice for the main drive axle on electric vehicles. ZF also produces an asynchronous motor (ASM) version, which is mainly used on the secondary drive axle. Furthermore, ZF supports the less common ESM version, a separately excited synchronous motor which is ideal for price-sensitive segments. Delivery reliability for certain raw materials notwithstanding, ZF is well prepared.
Performance across the motor range starts at 50 kW for basic electric vehicles. At the top end of the scale, 400 kW electric motors deliver the power for premium sports cars. ZF's electric motors for heavy-duty trucks offer the same performance. All units are based on a modular kit. Besides 400 and 800 volt variants, this setup allows various performance options for each motor: "Customers can choose from water-, oil- or slot-based cooling. This option can also influence continuous power and product costs," says Roland Hintringer, Head of the Electric Motors Product Line.

"Hairpin" becomes key element

"Hairpin" becomes key element
The hairpin winding is becoming the technology standard inside the motor. The production lines first preform the copper wire sections for the subsequent stator so they resemble a hairpin. These are then inserted mechanically, twisted together and connected individually. This increases motor efficiency substantially, but presents challenges for production. Process automation is expensive and constant precision challenging. "ZF was one of the first to invest heavily in this technology about four years ago. That's why we're now one of the few manufacturers that can reliably use this complex hairpin technique," explains Gehring.
"Development and production must be closely intermeshed to deliver good electric motors, ideally at the same location," explains Hintringer. Pilot lines help ZF achieve this important goal. "We can therefore perfect the processes and systems to manufacture an excellent hairpin electric motor at a high cycle rate." ZF transfers the tried-and-tested processes on these pilot lines to production locations worldwide. "Thanks also to the modular kit and pilot systems in particular, we can now halve the time between start of development and market launch for an electric motor," explains the product line manager.
"Thanks also to the modular kit and pilot systems, we can now halve the time between start of development and market launch for an electric motor."
Roland Hintringer, Head of the Electric Motors Product Line
During the hairpin winding, the production lines first preform the copper wire sections for the subsequent stator so they resemble a hairpin.

Flexibility halves time-to-market for electric motors

Flexibility halves time-to-market for electric motors
Markets are volatile. Quantities that customers plan or call off today may well be obsolete tomorrow. You must always be prepared for unexpected slumps or – as with ZF's electric motors – a boom in demand. The Group therefore relies on modular, standardized production lines. These ensure the required flexibility: Several types of electric motors can run simultaneously on a single assembly line – while rapid system expansion allows volumes to be ramped up quickly. "These highly versatile production concepts are key elements in today's industry transformation," says Hintringer.

A good electric drive must be able to compete on price

A good electric drive must be able to compete on price
ZF's features rank among the best from product to production. But what about costs? Here too, the motors from ZF are even more compelling, as the electric motor for the Mercedes-Benz EQA demonstrates. It delivers the most kilowatts (continuous power) per euro. What's more, none of the competitors can offer more Newton meters for the money.
This way, ZF could soon become one of the largest global electric motor manufacturers. The next three years will prove decisive – or, to be more accurate, the electric motors ZF is now developing and fine-tuning for the start of volume production in 2024. "Those are our rough diamonds," emphasizes Hintringer.
"The electric motors ZF is now developing and fine-tuning for the start of volume production in 2024 are our rough diamonds."
Roland Hintringer, Head of the Electric Motors Product Line