The 'modern' Hybrid Electric Vehicles (HEV) of the 1980s were investigated to overcome the limits of battery electric vehicles in terms of allowable range and recharge time.
According to this approach, the solutions developed were mainly based on series-range extender hybrids and parallel architectures with extended pure electric (zero emission) range targets. Their high weight-to-volume battery packs made it impossible to apply these vehicles to the mass market.
The current HEVs for the mass market have been designed by sacrificing the pure electric extended range and utilising newer generation, higher specific energy and lower cost batteries.
These powertrains can be regarded as co-operative hybrids or electrically-assisted ICEs (internal combustion engines). The electric contribution is aimed primarily at reducing the consumption of fossil fuels and CO2 emissions.
The related figures are reassuring as to gasoline engine HEVs, showing an increasing passenger car market in Japan and North America. In Europe, with its greater use of diesel vehicles, it is possible to achieve similar reductions at a lower purchase cost.
To continue with the reductions in regulated and CO2 emissions while developing new solutions with mass-market applicability in Europe.
Hi-CEPS aimed to operate, with an effective synergy approach on the devices, a strong step forward to reduce this gap with European environmental friendly and fun to drive solutions at an acceptable cost and customised for the European application conditions.
The objectives were:
- To develop three different, innovative, integrated series-parallel full hybrid thermal-electric powertrains utilising low-cost and standardised electric devices (e-motors, power electronics and batteries), vehicle auxiliaries and dedicated gasoline, diesel and natural gas engines with specific exhaust after-treatment systems. The adaptation to future fuels and combustion systems will also be taken into account.
- To achieve, at vehicle level, both the environmentally friendly requirements (fuel consumption, CO2 and regulated noxious emission reduction) and fun-to-drive characteristics (enhanced transient performance, driveability and comfort) at an acceptable purchasing/operation cost (perceived value).
In order to obtain these results, the following three actions were envisaged to be performed:
- improve the powertrain efficiency to deliver a larger consumption reduction;
- reduce the extra costs through:
- electric device improvements and standardisation (synergies with the running Hy-SYS IP and among the threee concepts);
- powertrain component integration and simplification:
- act on the 'final user functions' (performance, driveability, comfort, etc.) increasing the perceived value.
The project was structured into six subprojects (SPs). One SP was devoted to the project management (SP1000) while the other five were devoted to technical activities.
The five technical SPs were subdivided in three vertical and two horizontal SPs.
Vertical subprojects (one for each new hybrid powertrain) were:
- SP3000 - ElectroMagnetic Split Hybrid: with CNG ICE, for passenger cars, up to vehicle validation level;
- SP4000 - Dual Mode Split Hybrid: with gasoline ICE, for passenger cars, up to vehicle validation level;
- SP5000 - Advanced Dual Clutch Combined Hybrid: with diesel ICE, for light delivery vehicles, up to test bench level.
Horizontal subprojects were:
- SP2000 covered the integration of thermal auxiliaries (electrical regeneration, thermal storage systems, air conditioning) and energy management to reduce fuel consumption and emissions, whilst maintaining high thermal comfort for complex hybrid powertrains;
- SP6000 focused on the boundary condition and load cycle definition, and the final comparative performance and cost assessment of the investigated hybrid systems, taking into account the vehicle safety and powertrain integration needs.
Main results achieved:
- investigations of components and strategies for thermal and energy management;
- HEV powertrain architectures definition and system & devices specs;
- auxiliaries usage profile and test procedures;
- HEV powertrain design & prototype realisations, bench test, vehicle integration and in vehicle test;
- cost analysis tool development;
- simulation based performance assessment;
- cost assessment.