Like all major automotive OEMs, German giant Volkswagen uses a variety of software from the big-league PLM players. Siemens Digital Industries PLM suite Teamcenter is the backbone of the company in terms of cPDm (collaborative Product Definition management), while Dassault Systèmes’ CATIA is the main CAD solution.

However, this does not prevent Volkswagen, from needing and using more specific sub-PLM solutions for particularly tough problems. COMSOL Multiphysics is a good example on the CAE and simulation side.

Rotors are essential components in electric drives, and as such need to be tested for durability since they must endure a very large number of revolutions at varying speed and torque during drive operation. But evaluating rotor laminations strength is time-consuming. This is a primary reason why VW Kassel’s site in Germany is automating this test process for rotors, as well as reducing development costs and increasing product quality, by building simulation applications with the COMSOL Multiphysics software.

The VW case isn’t an exception, claimed COMSOL´s CTO Ed Fontes, when I discussed the matter with him.

“Correct,” Fontes said. “Our software has traditionally been used in central R&D departments, both in motors and batteries for electromotive applications.”

In the case of VW, COMSOL Multiphysics plays an important role when it comes to simulation in connection with the development of electric motors at the Volkswagen factory in Kassel. This plant specializes in the development, planning and production of electric units, and completes 150 electric and 300 hybrid cars every day.

In connection with the start of ID.3 model production, VW revealed that it is planning to produce ‘up to 1.4 million electric drives’ of their MEB platform motor, which is small enough to fit in a gym bag. This motor is produced at VW’s component site in Kassel, Germany and at a Chinese plant in Tianjin. With the two factories combined, they plan to have a capacity of up to 1.4 million electric motors per year starting in 2023. VW also makes the rotor and stator at its component plant in Salzgitter.

VW explained the details in a press release: “The rotor and stator are produced at the component plant in Salzgitter. New hairpin technology has enabled the use of an innovative production process for the assembly of the stator, whereby the spaces within the laminated core of the stator are optimally filled with flat preformed copper coils. This increases the torque density and the efficiency of the electric drive in comparison to that of a drive with wound copper wire coils. Maximum torque is achieved even at a low engine speed, which means that a 1-speed gearbox is sufficient for the entire rotational speed range. Both the electric drive and the 1-speed gearbox are produced at the component plant in Kassel.”

This may sound complex, but like all other electric motors, the MEB motor is much less complex than a conventional gas or diesel engine. In fact, the MEB motor contains a fraction of the number of parts you can find in a “normal” combustion engine. This underlines an existing trend where product development is radically changing as a result of the move towards a position where the mechanical content decreases, while electronics and software content increases. This will also be reflected in new needs for expertise and competences, which will no doubt affect product realization methodology and the structure of the workforce. It will all end up in new digital toolboxes alongside changing product development methodologies where PLM/cPDm, simulation, software and manufacturing integration such as Operational Technology (OT) are growing in importance and use. It all becomes extremely complex.

Why COMSOL Software?

That is the background to VW’s use of COMSOL Multiphysics. What makes a company choose a COMSOL solution?

“The ability to formulate own equations and to specify materials as functions for dependent variables has been the key function,” explains Fontes. “However, being able to create dedicated user interfaces, which are easy to use for researchers and engineers, has opened to departments outside R&D that utilize our software. This has happened gradually over the past two or three years. These scientists and engineers are not always simulation specialists, but with simulation applications they can also benefit from multiphysics models with high fidelity for electric motors and batteries."

The idea of reaching beyond the traditional user groups is an exciting development in an area that was normally considered difficult and complex. The secret is called Application Builder and COMSOL Server. These solutions, which became available a couple of years ago, have contributed to COMSOL having almost 200,000 users, according to Fontes. The solutions are used to make advanced multiphysics simulations available to a wider audience, and through Application Builder and Server, simulation specialists can create easy-to-use customized graphical interfaces (simulation applications) based on models built in the Multiphysics software.

The specialized analysis tools are then distributed with COMSOL Server. Administrators have full control over who should have access to the simulation applications. The fast and scalable process allows companies to spread simulation applications throughout a global organization within minutes.

"Everyone, from design engineers to tech sales people, can be more effective with these tools when they can perform or watch simulations with the Multiphysics program from a mobile phone or tablet," says Ed Fontes.

From COMSOL's Case Book: Simulation Application Accelerates Design Process at VW Kassel

These solutions fall into one of the clearest trends of recent years: ease of use, which facilitates collaborative development work.

The automotive industry has long discussed the need for effective collaboration in product development work. At the Kassel plant, this is already the case for development work. Today, there is a process around electric power solutions, which from the start of the development process have been characterized by close collaboration between everyone involved in design, simulation and testing.

The simulation bit is the essential part of this process, and is where the COMSOL multiphysics solution comes into play. Because rotors are important components of electric drive units they need to be tested for durability, as they have to withstand a large number of turns with varying speed and torque while driving. However, it is time-consuming to evaluate the strength of the rotor laminations. VW Kassel got around this by automating the testing process for rotors. The result is reduced development costs and increased product quality by building simulation applications with the Multiphysics software.

Schematically, it looks like this, as described by Thomas Forrister on COMSOL's site:

First, simulation experts review the performance specifications of an electrical device. Simulation is used to investigate how best to achieve the desired design. For example, by modeling the drive to greatly reduce the number of variants. By distributing a simulation application based on this model, it will be possible for designers to compare different variants and choose the best one at the next stage.

This collaboration is beneficial for everyone, as simulation cannot cover all real issues. Testing therefore plays an important role in the development process. In addition, the experimental test procedure helps to improve the simulation models.

“In the development process for electric machines, many requirements must be met,” explains Dr. Steffen Rothe, simulation engineer for component development at VW Kassel. “On the one hand, the machine must match the electrical requirements for torque and power. On the other hand, the rotor must have a certain durability, where the centrifugal force is the greatest load for the rotor.

"Balancing Requirements"

Balancing dual requirements can be challenging going forward, as they are sometimes unseen. Although it is better to use thin structures for the electromagnetic requirements, thicker structures are preferred for mechanical durability. It is important that these requirements are met early in the development process. One way to do this effectively is to simulate all load cases that cover the requirements.

“Simulation plays an important role in speeding up the design process,” Rothe comments. “Many industrial simulation programs are designed as a ‘black box’ while COMSOL Multiphysics is unique in its transparency. It allows users to view and modify the implemented equations, or even add their own.”

The software is additionally designed as a multiphysics tool from the beginning, and allows users to simulate different physical fields simultaneously. Therefore, the user can combine different physical fields to do something completely new.

However, analyzing complex physical problems such as these can be challenging, even for a simulation expert. The team needed a way to communicate with colleagues and enable non-experts in mechanical simulations to test certain parameters. The designers were able to meet these needs by using Application Builder in COMSOL to create simulation applications that predict the voltages in a rotor.

The conclusion was that VW Kassel sped up the design process for electric motors by building and distributing simulation applications that evaluate the strength of rotor laminations.

It is a good indication of COMSOL’s ability to create world-class solutions that can break the dominance of the really big developers.

The full COMSOL case study can be read here.