Interview: Audi’s Györ Director of Electric Propulsion Systems on EV Motor Production for PPE

– For the manufacture of electric motors, three new lines have been implemented, with an initial production capacity of 2,000 motors per day
.- The propulsion systems will initially be used in the new Audi Q6 e-tron
.- From 2022, about 2,000 employees in Győr have received specific training on electrification

[source: Audi España, translation by Apple]

Audi manufactures electric motors for models based on the Premium Electric Platform (PPE) in the largest propulsion system plant in the world, in Győr (Hungary). The propulsion systems will initially be used in the new Audi Q6 e-tron, which is produced in Ingolstadt. Its manufacture in Győr is carried out in a facility with an area of about 15,000 square meters, where the stator and transmission components are also produced, in addition to assembling the shafts. Csaba Imre Benke, Director of the Electric Propulsion Systems Product Segment at Győr and responsible for the production of propulsion systems for the PPE platform, explains how Audi is setting new standards with this advanced process.

Can you give us an idea of the scope of the production of the propulsion systems for the PPE platform?
Csaba Imre Benke: Three new production lines have been implemented to produce the electric motors of the PPE. The one intended for the manufacture of the stator has 28 workstations and the transmission components, 15. The assembly of an axle requires more than 190 individual steps.

How many employees do you have and how many electric motors do you produce?
Csaba Imre Benke: In total, about 700 employees participate in the production in three shifts, and are able to produce 2,000 electric motors every day. The electric propulsion systems we produce here are those intended for models based on the PPE platform.

What previous experience does the Győr plant have in the production of electric motors?
Csaba Imre Benke: The production of engines for the PPE platform forced us to learn a series of new processes. Each of our employees needed about 20 days of training. But we don’t start from scratch: we have manufactured more than 500,000 electric motors since 2018. Needless to say, our experience benefits us, especially since we are gradually going to increase our production capacity of electric motors. At the moment we are manufacturing the stators and transmissions ourselves and we also assemble the axles here in Győr.

What are the main differences with the production of the electric motors they used to manufacture?
Csaba Imre Benke: As for production, the propulsion system of models based on the PPE platform is in a completely different league. Due to the technical differences, the lines are different. Only for PPE we use 15 automatic bending machines to make the three-dimensional windings in a fork and two systems to laser welding the ends. Each stator contains 140 meters of copper wire, and 235 laser welds are needed in total to make one. Compared to models with a combustion engine, electric propulsion systems usually have fewer screwed fixings, but they need more pressing operations, so more robots can be used. In addition to increasing automation rates, the overall objective is to continue increasing our ability to manufacture electric motors for future projects. For example, unlike what had been happening with the Audi e-tron transmission, for models with a PPE platform we manufacture it ourselves.

People promote the electrification of the site. How long does it take to qualify employees to manufacture the PPE and what levels of qualification are there?
Csaba Imre Benke: The first level is a relatively simple basic training that takes about two hours for employees who work near the production line. These tasks do not differ much from the construction of combustion models. The difference is our “High Voltage Awareness” course that must be taken by each employee. The training aimed at the execution of much more complex tasks lasts a whole working day. Our “electrical specialists” receive a training of several days. “Electrical specialist in charge” is the highest level. It may take about three months to reach that level, depending on the basic training of the employee. For the most part, we rely on the staff from our combustion engine area. About 2,000 employees have received training on electrification in Győr since 2022.

Characteristics of the propulsion system for the PPE platform
The essential components of the Premium Electric Platform (PPE) are the high-voltage battery and propulsion systems. The latter are manufactured at the Audi engine plant in Győr, Hungary. The fundamental development objective was to achieve a scalable electric propulsion system with a high degree of integration, efficiency and power density.

The newly designed propulsion system consists of three main components: electric motor, power electronics (pulse width modulation inverter) and transmission. Together, each of the components stands out for its greater efficiency. They are designed to be scalable and more compact. As a result, the torque can vary by adjusting the length of the electric motor. The torque on the wheel and the maximum speed are influenced by the transmission by the coupling of the gears. New electric motors also require 30 percent less space. In addition, the new design has made it possible to reduce the weight by around 20 percent.

Greater efficiency: A significant advantage of redesigned electric motors is their efficiency. This is mainly contributed by a new fork winding in the stator, silicon carbide semiconductors in the pulse width modulation inverter and an electric oil pump in the transmission. The new fork winding maximizes current conduction in the electric motor stator. This method also allows a greater number of windings: the proportion of the motor section occupied by the copper winding is now 60% instead of 45% presented by the conventional windings used previously. Thanks to the oil cooling of the engine, Audi has also been able to avoid the use of rare earths as much as possible. In total, the losses caused by the resistance in the electric propulsion systems were significantly reduced by 50 percent.

Higher power density: The direct cooling of electric motors with oil, used for the first time, keeps components such as stator winding and motor permanent magnets in the optimal temperature range. As a result, the weight-to-power ratio of the PPE electric propulsion system is approximately 60 percent higher than that of the first-generation electric propulsion systems.

Optimized acoustics: The new electric propulsion systems of the PPE platform also stand out for their especially quiet and comfortable acoustics. The motor supports molded in the structurally optimized housing, the improved geometry of the gear teeth and the segmented rotor contribute to this.

Greater vertical integration: Another important factor for the successful development of the electric propulsion systems of the PPE platform is the considerably expanded vertical manufacturing range in Győr. The largest propulsion system plant in the world not only manufactures electric motors, but also most transmissions.

Custom electric motors: When accelerating to maximum power, an asynchronous motor (ASM) located on the front axle comes into action. The ASM does not contain magnets; it generates its magnetic field by induction and, therefore, if necessary, it can rotate freely without significant losses due to slippage. On the rear axle there are extremely compact permanent magnet (PSM) synchronous motors, exclusive to the Q6 e-tron series.

The 800-volt architecture saves space and weight: The 800-volt technology used in the PPE not only offers high performance and short charging times. As a result of the higher electrical voltage, thinner cables can be used to wire the battery and the electric motor. This reduces the installation space, weight and consumption of raw materials. Another advantage is the lower heat loss, which reduces the need for refrigeration.