MODELLING AND SIMULATION Racing ahead


GEMMA CHURCH FINDS OUT HOW ELECTRIC VEHICLES CAN MAKE PERFORMANCE AND USER EXPERIENCE IMPROVEMENTS


As the internal combustion engine raced into the mainstream some 200 years ago, electric vehicles


were left at the starting line due to the complexity of the design process. The storage of electrical energy and


its conversion to mechanical energy is an overriding challenge when designing such vehicles. You must also take into consideration the multiphysics nature of simulating an electric vehicle. Mark Walker, application engineering manager at MathWorks, said: ‘Electric vehicle simulations depend on the interaction between multiple domains much more than internal combustion powertrain development. For example, effective battery management depends on a well-validated understanding of the electrical and thermal domains.’ Walker added: ‘Models are especially


important because one of the most important variables in controller design – battery state of charge – cannot be directly measured. By contrast, most variables in traditional powertrain design are observable.’ Quality and safety standards add


another layer of complexity as Frédéric Merceron, transportation and mobility solution experience director at Dassault Systèmes, explained: ‘Software is of very high importance [in any vehicle design process, but] even more so with electric vehicles. This is why the embedded systems now have a quality and safety standard (ISO26262) on top of all the other standards that car manufacturers and suppliers have to conform to.’ But the electric motor is gaining ground


on its conventional combustion engine counterpart. Simulation and modelling are helping to unlock the complexities of electric vehicles and demonstrate the benefits to consumers and the wider transport industry. David Moseley, manager and CAE analyst at electric car company Lucid Motors, said: ‘If we tried to design a vehicle without the aid of integrating simulation and modelling, then we would have a poor vehicle in terms of the design and acceptance by the public. We need to use sophisticated design space exploration to be competitive.


‘Simulation and modelling provide such


exploration intelligence. We can get a solution that is better in performance than a human could achieve with a purely holistic approach [but] this requires high investment in the right engineers and the right analysis capability,’ Moseley added. Lucid Motors is developing a new class of premium electric vehicle, and its first Lucid Air all-electric sedan is due to be launched in 2019. In preparation for production, Lucid Air prototypes are currently undergoing a rigorous development programme, which incorporates Esteco’s modeFrontier software.


Such simulation, modelling and optimisation tools are, generally, used for two main design areas for electric vehicles: the system design and the simulation of the vehicle at a range of fidelities. For the system design process, trade-


Gearbox for an electric vehicle


26 Scientific Computing World October/November 2017


offs are necessary to meet the range of requirements demanded to produce a viable, and competitive, electric vehicle. To address this issue, Altair has developed


a three stage concept development process, called C123, where optimisation technology is deployed at each stage of the design process. C123 provides the designer with structural data relating to the mass and attribute performance consequences of various design decisions and helps them to manage target trade-offs. Throughout the process, the sophistication of simulation technology is matched against the maturity of the available design data. ‘The designer must make some tough choices on what technology to use and this really helps them make the best call for the overall design,’ Richard Yen, senior VP of auto engineering at Altair, added.


Dealing with multiphysics If we drill down to the component level, then the multiphysics nature of such components and their impact on the wider vehicle performance must be addressed. For example, let’s look at a motor


rotor, a moving component of the electromagnetic system in an electric motor. Its rotation is due to the interaction between the windings and magnetic fields, which produces a torque around the rotor’s axis. As such, the design of the rotor is important with regards to the electromagnetics of the system. But,


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