The global electric vehicles market is projected to grow very significantly, primarily driven by the need for eco-friendly alternatives for transportation. Electrification now lies at the topical forefront of the automotive industry. In turn, SMT have focused on developing the MASTA software package to encompass electrification, allowing users the ability to analyse and optimise the drivetrain for an electric machine.
Recent years have seen an increasing focus on the noise impact of the gearing required for the transmission of power from the (high speed) electric motor to the road. NVH issues often arise at prototyping and in-vehicle installation phase, in which time-scales for solutions are short and commercial pressures are high.
SMT have developed methodologies in which NVH issues can be addressed at the development and design phases– through a combination of detailed measurement and computer aided engineering solutions. The demand for a deeper understanding of the noise reduction methodologies in all drivetrain components is driven by a combination of industry regulations and customer expectations.
SMT has over 12 years of experience of transmission design and development for Electric Vehicles and has delivered many EV gearbox projects, covering bearing issues, efficiency improvement, NVH improvement, development and production support including validation test plan, prototype manufacturing quality. MASTA models can be built for EV and HEV applications including modelling and analysis of a number of effects from the motor.
A customer might have a gearbox that is noisy, but by using MASTA we can identify the source of the noise and improve the design
MASTA Benefits for EV + HEV
- Analyse the response of the model to the excitations from the electric machine, transmission error at gear meshes and any other user defined harmonic loads in the same analysis
- Efficiently build transmission models for EV, and HEV applications with multiple power sources and compare topologies at concept design stage
- Import time series speed, torque data for multiple energy source systems and generate duty cycles or input duty cycles directly
- Add further model details for detailed design and advanced analysis of durability and dynamics
- Include electric machine stator and housing
- Design internal components and perform detailed component analyses within the context of full system models
- Calculate and maximise transmission efficiency for all operating modes
- Import speed dependant torque ripple and stator tooth dynamic loads from electric machine analysis software
- Achieve low gear and motor noise across all operating modes, particularly those with little or no ICE contribution
- Simulate transient power-shifts in multiple speed EVs or power source transitions in HEVs
NVH Response to Electric Machine – Dedicated functionality for EV/HEV Gearbox Development
- Include electric motors as power sources in a MASTA model
- Model and import the stator and housing via an Imported FE component. It is important to include a high-fidelity model of the stator via an imported FE model to accurately capture the stator/housing complex dynamic response
- The MASTA model captures mechanical coupling between motor and transmission
- Import speed dependant dynamic load data, including torque ripple and stator tooth loads, from:
- Test data
- Any 3rd party electric motor analysis program including e.g. ANSYS Maxwell, JMAG, MotorCAD, Opera, Manatee, MagNet, Flux.
- Include the effects of rotor/stator skew
- Analyse static deflections, durability of components, efficiency, loaded gear tooth contact etc. for the entire vehicle duty cycle
- Analyse the structure borne and airborne dynamic response of the system to the excitations from:
- Electric motor dynamic radial and tangential stator tooth loads
- Torque ripple
- Loaded transmission error at gear meshes
- Rotor unbalance
- Any other user defined harmonic loads in the same analysis
- Export harmonic boundary conditions on transmission/motor housings to 3rd party acoustic analysis tools for detailed acoustic analysis
Hub E-Drive found to be too noisy as installed in production bus with high unit-to-unit variability
- Extensive testing, MASTA modelling and development of design changes
- Significant design changes and modelling results to identify and quantify the manufacturing requirements for the critical dimensions for noise control
Significant noise reductions achieved in prototypes, understanding of manufacturing changes to be implemented to maintain this
Gear Blank Tuning of an EV Gear Box
In the latest issue of Gear Technology, the software and research team at SMT have produced a technical paper on “Electric Vehicle Whine Noise – Gear Blank Tuning as an Optimization Option”. This article reviews noise issues from gear and motor excitation that are commonly faced by many within the EV and HEV industry. The authors include SMT’s Owen Harris, Director of Research; Paul Langlois, Software Engineering Director and Andy Gale, Research Engineer who present an advanced CAE methodology for troubleshooting and optimizing for such NVH phenomenon.