Electrification of vehicles is poised to transform the transportation industry. Driven by the requirement for innovation and environmental regulations, vehicle manufacturers must revolutionize their approach in developing the next generation of more efficient and convenient-to use vehicles. How can these increasingly complex systems be built within time and budget constraints, while meeting customer requirements for performance, reliability and quality?
Model-Based Development efficiently addresses the global powertrain analysis
MBD is a process that helps to manage and reduce the risk of creating complex systems. This process relies on simulation models and flows from abstract to the specific, which means that design starts high-level with system-level requirements, and flows from functional to detailed system models to component models.
This approach pays dividends by providing many benefits, such as testing designs earlier in design process, integrating multi-domain systems in an open environment or leveraging the knowledge of different systems into one model.
Depending on the stage of design, engineers may need different levels of fidelity of the model and use either 1D or 3D simulation tools, or both. For example, system models implementation in ActivateTM can help with supervisory control energy flows, for fuel economy and the electric machine design and controls. In such cases, one main goal is to determine how to best use power sources – engine and one or more motor/generators - to efficiently use fuel and electric energy stored in the battery at desired levels of performance. This can be used to both evaluate vehicle topology, perform component sizing and set subsystem requirements.
The complex hybrid vehicle powertrain systems in Activate model-based development environment
From electric motor pre-design to its validation
The next step is to use a motor predesign tool such as FluxMotorTM, which enables quick design, estimates and comparisons of machine performance in a single platform and provides the functionality to edit various reports including important results like cogging torque or efficiency maps, with accuracy within minutes. Work which used to be done by different engineers, often using individual tools, can now be automated, easily shared and documented. At this stage, various specifications should be predefined and models can be exported for more advanced studies and even early optimization.
Vehicle autonomy remains a major purchasing criteria, with drivers looking for the same level of performance as traditional cars. Automatically generated 2D or 3D models studied in FluxTM software will ensure an accurate view of the machine performance, including its efficiency, focusing on advanced modeling of losses; for example, checking local behavior between laminations or hysteresis phenomenon, while considering cost impact or controllability.
A multi-physics design platform fostering multidisciplinary team approach
Since most of the losses are heat dissipated, transient thermal analysis can be run in the Flux environment, or even in CFD software such as AcuSolve®. Simulation iterations can consider component temperature, improvements to the cooling and overall performance during the operation cycle.
The other consideration once the vehicle’s range and acceleration has been optimized, is linked to acoustic comfort. Coupling Flux with OptiStruct® structural analysis software enables the evaluation of the vibroacoustic performance of the machine. Electromagnetic parasitic forces are the source of vibrations and noise, which remain challenging to reduce. Adapting the control strategy, adjusting the shapes of the rotor and stator, and optimizing the mechanical structure of the machine, requires a specific approach to remain efficient.
Altair Multiphysics simulation platform efficiently accelerate the powertrain design process
Driving global performance with Multi-Domain Optimization
Improving performance using a cutting-edge multidisciplinary optimization process managed in HyperStudy®, while coupling Flux electromagnetic models with OptiStruct structural analysis, changes the design approach. Models are easy to set up and use – making design exploration and optimization efficient.
Finally, powertrain performance will depend on a combination of the power electronics driving the machine, and secondary functions such as current flow with energy storage, transmission, injectors, and the powertrain configuration in general. They can easily be integrated in the Activate system.
Implementing an efficient drive
The electric drive is a key component of the electrified vehicle powertrain. The motor controller is a strategic subsystem in the HEV fuel simulation model which has a big effect on the performance of the motor behavior. To control the motor, field-oriented (vector) control is often used which provides a robust method to control the torque efficiently. Different models are used to convert the 3-phase voltages into a rotor-fixed reference frame and allow the control designer to directly control the torque and the magnet flux.
Driving scenarios are considered in co-simulation, coupling Flux to ActivateTM, and the electromagnetic electric one to test according to evaluation of energy consumption on different homologation cycles. EmbedTM software will later automatically edit optimized and compact code in the controller.
Different electric machine models can be integrated in the powertrain drive system
Altair’s broad and deep solution spans high level system view to detailed 3D domains multiphysics analysis to help leverage the right tools to meet the challenge in designing electric machines in complex systems. Moreover, Altair HPC capabilities together with a flexible licensing system, easy models exchange within HyperWorks platform are key to foster multidisciplinary teams work across R&D departments, to implement new simulation driven processes and improve project performance.