By Julie Ercolani-Peck, Industry Marketing Manager, Automotive & Transportation – Simcenter, Siemens PLM Software
Our world is changing quickly. In 2013, the CO2 concentration in the atmosphere was the highest recorded ever, with 2001 to 2010 being the warmest decade. The Max Planck Institute for Meteorology says that only an immediate, drastic reduction of CO2 emissions can keep global warming below 2°C until 2100. Moreover, an incremental growth of cities will affect the worldwide demography: by 2025, the world will have 27 megacities with more than 10 million inhabitants – roughly one in ten people will live in a megacity. By 2050, 70% of mankind will live in cities.
Fossil fuel resources are becoming scarcer, driving an increasing focus on renewable energy. Hence, efficient use of energy is the underlying imperative for future mobility. Market forecasts confirm a trend towards electrification. Digital transformation, globalisation, urbanisation and demographic and climate changes are leading to new ways of thinking about innovation, design and production, paving the way for digitalisation, automation and electrification. This means evolving from traditional power generation sources to advanced power transmission and distribution with smart grid technologies and efficient energy applications. Electromobility will be the only way to drive cars in the future, with hybrid cars in the interim.
Focus: Car Electrification
Werner von Siemens developed the first electric railroad over 130 years ago and, since then, electric drives from Siemens have been successfully applied to many industries. Siemens is now bringing its long history in electric drive technology to the electric car with innovative components for hybrid and electric vehicles – from motors to charging technology.
Within the Siemens Digital Factory Division, the Siemens eCar Powertrain Systems (Siemens eCar) business unit develops high-quality powertrain components and charging systems for serial production of electric and hybrid vehicles.
“Electric powertrains are critical components of the mobility of the future,” says Wolfgang Nebe, director of system technology at Siemens eCar. “With our expertise in developing powertrain components, we offer car manufacturers appropriate solutions for the electrification of their powertrains, whether they are cars or trucks, or hybrid or fully electric motors.”
After pioneering electric vehicles in the 19th century, Siemens is aiming at becoming a global system provider for low-emission electric mobility. This means stringent high-level requirements, as well as functional safety, traceability and transparency for these systems and components. Being a Tier 1 supplier is very challenging due to the high expectations and quality standards of automotive OEMs. Streamlining design and collaboration processes at every stage of development and production requires precise traceability to anticipate components failures and correct them as quickly as possible. Delivering customised products makes the design and development process more complex, and usually requires additional development time.
“The mobility of the future definitely involves collaboration among all parties. We now have to stand not only as a component supplier, but as a system integrator, being able to develop products that fulfill customers’ requirements,” said Nebe.
The Siemens eCar business unit markets components for the drive trains of hybrid and electric vehicles for sustainable mobility. For automobile manufacturers, the company offers high-quality powertrain components including motors, power electronics, inductive charging technology, helping achieve clean, sustainable and, above all, quiet mobility.
To cope with their customisation and flexibility challenges, Siemens eCar decided to use system simulation early in the development process, to validate technology decisions at each step of the way to avoid mistakes that could add costs and delay the delivery of projects. The company decided to implement the Siemens PLM Software model-based systems engineering approach, and selected Simcenter Amesim software.
Integrated drive units
Assessing the Model Behaviour
In electric vehicles, the drive system generally consists of electric motor, inverter, battery and charger. For the electric drive to propel the vehicle, the motor must be fed with an alternating current, which is supplied by the inverter. The inverter converts the direct current from the battery to an alternating current.
The inverter also controls the vehicle’s speed, by increasing motor power as the driver accelerates. It is crucial to assess and optimise all these systems’ interactions to ensure best efficiency and performance.
To assess these components’ behaviour at the complete vehicle level for early architecture definition of hybrid and electric vehicles, Siemens eCar developed a comprehensive tool chain and simulation platform. The objective was to get a first insight of the vehicle performance when integrating Siemens’s electric components.
First, Siemens eCar engineers build the model of a vehicle, a super component and standardised architecture for the model (combustion engine, transmission, electric engine, driver and other elements). Then, based on the objective of the simulation and the application, the level of detail of the component to be simulated is chosen. Finally, the engineers integrate the specific components, such as the electric motor or inverter, parameterise them and analyse the performance of the complete vehicle in which they are integrated.
The engineers analyse different aspects of the vehicle; for example, if the inverter and motor fit together, or if there’s an overload. They generate load profiles, check efficiency and component losses, then define the first requirements for the cooling system to enable optimal operating conditions.
Simulation helps them to define requirements for detailed engineering of products, with more detailed models of the motor – as well as the synchronous motors of the inverter machines – to analyse the inverter performance (power electronics and control electronics), bus bars, cooling and thermal behaviour.
Integrated inverter and DC/DC converter
Model-Based Systems Engineering
Siemens eCar began using Simcenter Amesim tools as simulation became mandatory to support an optimised development process. The deployment of these tools enabled the company to predict the required component efficiency and to support the development of a streamlined design and customisation process for all e-mobility devices.
The Simcenter Amesim multi-domain approach validated the application and physical libraries (hydraulic, thermal, combustion engine, transmission and others), helping visualise the energy flows and seamlessly model many aspects of the system. Using the architecture definition and functional model, Siemens eCar can automatically generate architecture with stored models, and assess its performance.
“The implementation of model-based systems engineering is driving our innovation platform, and enables us to combine architecture definition with simulation capabilities to validate technical choices early in the design cycle,” said Nebe.