Overview
Promotion of Electric Vehicles is strategic for the European Community, but nowadays battery performance is still poor and all forecasts for near future transport electrification suggest that A-B class EV cars with limited range are the first step to develop. Even in the actual economic crisis, global demand of A-B class cars is expected to grow by about 5.3% in 2010, with a positive sale scenario in the next years. In-wheel electric motor architecture holds major advantages for these A-B class, allowing high modularisation of the vehicle architecture, increased interior space and improved driveability. However, current existing solutions for in-wheel motor are still in prototype phases, resulting in non-existence of A-B class EV car commercialized and equipped with in-wheel motor, even though the predicted market for this technology is 100K vehicles for 2015.
The main objective of this proposal is the design, development and validation of a complete in wheel motor assembly prototype (electric motor, power electronics, reduction gear, structural parts and wheel), based on a McPherson corner suspension topology, to meet the defined car top level specifications.
The main technical risks associated with the use of an in-wheel concept are the thermal stress under extreme operation conditions, vehicle dynamics, driveability, safety and durability. The proposed baseline concept will be based on an air cooled motor in wheel concept, with conventional airflow driven by vehicle, and forced airflow provided by an innovative wheel design. Detailed specifications of extreme operation conditions will be defined and validated by the OEM, during the project, including the hot day-cold day conditions, representative of vehicle extreme use. During the assembly and testing phase, the aspects related to vehicle dynamics, driveability, safety, user acceptance, reliability, previously defined, will be validated with the motor in wheel prototypes installed in a test vehicle. In addition, aspects as eco-design, LCA of the concept and components, dismantling and recyclability of key materials and rare earths will be considered during the in-wheel concept design.
Objectives:
- Motor efficiency map improvement based on real representative driving cycle (mix of USA-FTP75 – USA Highway – NEDC, total 100 Km) not on peak efficiency
- Air cooling, integration simplicity. Air cooling is a very challenging target, and offers market penetration competitive advantages
- Power electronics integrated in the motor cover with cooling capabilities
- Rotor. Polymeric composite with assembled magnets able to withstand high rotation velocity.
- Effective integration of gearbox oil circuit to remove heat generated in the motor stator.
WP1: E-CORNER SPECIFICATIONS
The preliminary requirements and specifications of the DoW, used during the preparation of the proposal, will be defined in detail by PIN, in order to establish the required performance of the EUNICE solution and the acceptance criteria for different aspects. The baseline E-corner option is air cooled with wheel integrated power electronics and motor, proposed in order to develop a solution that would meet the above stated performance requirements while responding to the proposal objectives. The mentioned baseline is to be assessed and evaluated during this WP, using multi domain simulation and optimization tools (theoretical assessment). If the optimisation of the baseline concept is not able to meet the requirements, a series of alternatives will be evaluated, until an acceptable motor in wheel solution is achieved, taking into account performance, vehicle dynamics-driveability, safety, endurance and user acceptance. To summarize, the main objectives of this WP are:
To define in detail the specifications and performance of the EUNICE solution, oriented to a B-segment type vehicle.
To perform a functional analysis of each of the sub-modules that will integrate the e-corner, in order to define the basic requirements for their design.
To analyze the EUNICE proposed baseline design and alternatives, based in their performance and their fulfilment of the proposal objectives.
To select the best concept which will be developed in the following WP´s.
To continue the patent study, covering all the components that will be developed within the project.
WP2: ELECTRICAL COMPONENTS
This work-package is committed to the development and manufacturing of the electrical components of the e-corner, the e-motor, and power electronics, together with their related sub-systems such as cooling system and safety system. These components will be designed, manufactured and evaluated. Their design will follow the eco-design guidelines, from WP1. Also, LCA, material benchmarking and dismantling/recycling of the rare earths, will be analysed when designing the e-motor. In detail, the objectives of this work-package are:
To design the e-motor and power electronics, following an effective eco-design guidelines.
To develop the cooling system, specific for the e-motor and power electronics.
To develop the optimum motor control strategy for the E-corner application.
To manufacture the e-motor and power electronic components.<br
Funding
Results
Novel concept for sustainable electric cars
Today's electric vehicles (EVs) suffer from relatively high buying prices. An EU-funded project is developing and evaluating a new integrated electric motor concept in which the wheels are housing the entire powertrain except the battery.
With EU funding of the 'Eco-design and validation of in-wheel concept for electric vehicles' (http://www.eunice-project.eu/ (EUNICE)) project, researchers are working on developing a complete in-wheel motor assembly prototype. Despite an expected market of 100 000 vehicles for the technology by 2015, most existing in-wheel designs are still at the prototype stage.
Except for the wheel and the electric motor, power electronics, structural parts, brakes and a reduction gear are also parts of the prototype system. The proposed concept is based on a widely used front suspension system — the MacPherson strut — and should be able to meet typical B-segment EV requirements.
To develop and evaluate a concept car, focus will be placed on factors such as thermal stress under extreme operating conditions, vehicle dynamics, driveability, safety and durability. Attention is paid to aspects such as eco-design, component and whole-car life-cycle assessment analysis, dismantling, and recycling of important materials such as rare earths. The in-wheel motor concept provides greater scope for revolutionising the vehicle architecture, greatly increasing the interior space (the only remaining part to be housed in the car body is the battery) and improving driving performance.
Project partners have defined the specifications and performance criteria for the EUNICE solution. Furthermore, they have performed a structural integrity and mechanical integration analysis of the components. Other work has included a thermal assessment analysis of the electric motor and power electronics sub-modules.
Overheating is a great risk for in-wheel motors, particularly since the proposed concept features a fully air-cooled motor, with conventional airflow driven by the vehicle and assisted by an innovative wheel design. This ensures that enough airflow is provided to the in-wheel system to evacuate the heat in urban and motorway driving cycles. In addition, a fan is considered for the standstill case, whenever the car needs to drive slowly when the electric motor is at high temperatures.
With its activities, EUNICE is establishing the basis for a world-level European industry manufacturing electric motors and components with required performances at competitive costs.