This blog summarizes ASI’s approach toward electrification of conventional ICE vehicles. We bring together our experience in EV vehicle & EV powertrain performance benchmarking with the study of influencing parameters, and our experience in executing conventional turnkey design & development projects for various OEMs in India.
Fully electric vehicles (BEVs) powered by HV batteries can be produced in the following 2 forms:
- Create new EV platform (Design from ground zero)
- Electrify an already existing ICE vehicle
We all are familiar with the pros and cons of the both and this blog will not stretch those points more. However, we should keep our targets under control when we plan for electrification of an existing ICE vehicle due to confined limitations of space, packaging, existing tooling, time to market & project cost.
For instance, the battery pack size may get compromised due to the available space in and around your chassis & in case it does, instead of targeting a range of X we might have to compromise for X-α or 0-60 Kmph in Y- α secs instead of Y sec. However, the only challenge is to find out the best that can be done on the existing platform and how we can minimize α.
Commonization of parts between ICE and EV
Based on our assessment thorough previous projects (Teardown, Benchmarking & design of electrified vehicles), following is the approximate commonization percentage between ICE & EV on the same platform. This list helps in assessing the quantum of work & project time-plan.
Approximately 70% commonization b/w ICE & EV can be achieved if the design strategies are aligned with this target. Also, this can be used as an advantage in reducing time to market.
Project Workflow for vehicle Electrification
As shown in the picture above, the workflow for any electrification project (Upto alpha stage proto) can be divided into the following 3 main stages.
1. What to develop?
2. How to Develop?
3. Actual Development.
What to develop?
Target and Spec finalization for EV
This stage defines the boundaries of the product, where market survey & competitor benchmarking helps in deciding the features of your product.
It is conducted to understand EV specific customer expectations. What is it that market needs, a better vehicle dynamics performance, longer range of the vehicle, instant charging or Swappable battery, good looks, 5,7 or 15-seater, intercity or intracity travel etc.? Market study results can help us understand the trend and set our goals on similar lines.
Competition Benchmarking for EV specific as well as market driver parameters:
After identifying the same segment competitors, extensive performance benchmarking followed by teardown and functional analysis can help us define what other OEM’s are offering and at what value. Based on the performance test results, targets can be set considering cost & weight in check. At ASI we have completed more than 10 electric vehicle performance testing for benchmark and teardown for directional costing.
Few of the blogs on EV testing are as follows:
- HIL Testing
- Electric Vehicle Benchmarking, Target Setting & Cascading
- Electric Vehicle Range Measurement & Mapping
- Understanding ‘E’ in EV (Electric Vehicle) Development
At the end of the “What to develop stage?” we should have the final list of following target parameters:
How to develop?
Development of EV using existing ICE Platform.
With all the commonisation & performance targets we move on to the next stage for initiating the concept design at the functional level followed by a geometric level.
Functional level concept design for Electric Vehicle
To assess the performance of the final vehicle, all electrical components and related aggregates need to be modeled analytically to vary parameters and optimize the design for the best combination possible. As all components and their parameters are dependent on each other, the model should be verified with real case scenarios on actual components with vendor support. The model will ensure that the vehicle in simulation exceeds the performance targets by 10%-20% to accommodate correlation factors.
Following model has been prepared & improved with time on ASI Datalab software’s EV analytics suite which is equipped with all the customization tools required to model the EV & end up providing a reliable and an efficient electric powertrain model.
Few of the critical parameters considered in the model for various interlinked equations:
- Vehicle Mass
- Rolling Coefficient
- Aerodynamic Drag
- Path gradient
- Gear Ratio
- Acceleration due to gravity
- Wheel radius
- Inverter Efficiency
- State of Charge
- Electric Power
Once the EV specific component selection of powertrain is completed, next stage is to check the initial design layout for packaging & manufacturing which is covered in the geometrical concept design stage.
Geometric concept design for vehicle electrification
The above image shows the general packaging feasibility study conducted on an existing ICE. Based on the selected components size, the most feasible package is created and design is sent for detail designing stage.
Detailed System Design for Vehicle Electrification
The above snippet shows all the components procured and connected together to test on the bench for their performance and overall output (Power, Energy, Speed & Losses at multiple stages) and it is correlated with the mathematical model to check for the variations and scope of improvements. Based on our recent similar activity for a client the simulation model and the test results had 93%-99% correlation. And now we have an electric powertrain model that correlates well with the physical data and reduces overall development time by 30% (by reducing no of iterations).
Also, during the detailed system design stage design validation plan is finalized at component, system and vehicle level. This goes in the final performance drawings of components for which the specs will be released to vendors for quotation, prototyping and regular supply of parts.
Detailed geometric design (CAD & CAE validation):
The detailed geometric design workflow is as follows:
- Section design or stick model layout based on finalities concept design.
- 1D CAE simulation for initial validation for load cases such as bending (Local & Global), torsion and natural frequency.
- 3D modelling of all components
- 2D Mesh & CAE for final validation
- 3D update
- 2D Drawings and release for prototyping
Post this stage, sourcing and procurement teams float RFQ for designed components and their tool and the project move towards actual development stage.