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German engineering solutions provider has developed a modular chassis platform using lightweight materials such as aluminum to offer optimised range and performance attributes for electric buses.
27 Dec 2022 | 10727 Views | By Autocar Professional Bureau
With an intent to drive sustainability in the country’s public transportation system, the Indian government has outlined a roadmap to push electric mobility in buses, by setting a target to switch 40 percent of all buses sold in the nation to electric by the year 2030.
The government is ...
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With an intent to drive sustainability in the country’s public transportation system, the Indian government has outlined a roadmap to push electric mobility in buses, by setting a target to switch 40 percent of all buses sold in the nation to electric by the year 2030.
The government is driving this vision by the virtue of incentives and subsidies like the FAME-II scheme that are pushing public transport authorities across States to embark on a mission to introduce zero-emission electric buses in their respective regions.
However, the transition from a diesel-intensive bus network to an electric-bus system could be significantly challenging considering the fundamental shift in the technology, as well as the way the energy is transferred and stored. While diesel or CNG buses can be refueled within a few minutes, electric buses need more time at the charger to recharge their batteries, or in some cases, can also be constantly fed with electricity from an external source while they are on the road. PRESENT-DAY ELECTRIC BUS MARKET IN INDIA, OUTLOOK: The key driver of the electric bus implementation in the public transportation sector is the Indian government’s commitment at the COP26 to achieve net-zero emissions by the year 2070. Therefore, the e-bus market is expected to grow at a CAGR of 71 percent between 2022 and 2025, thereby making this segment one of the fastest growing in the nation’s e-mobility journey.
What is further enabling this e-mobility drive in the bus segment is the cost of these vehicles which is expected to reduce with the lowering of global battery prices as well as with the development of a local battery ecosystem that is being fueled by the PLI scheme on advanced chemistry cell (ACC) batteries. The government push under this scheme is opening doors for corporations to venture into domestic cell manufacturing in the country. Further more, the growing charging station network as well as the increase in battery life and range, are also promoting the e-bus market in India.
FEV’S E-BUS APPROACH
FEV – the German engineering solutions company has developed a holistic design methodology to identify the ‘most-suitable system solution’ under given strategic and operational requirements. The technology selection is based on a detailed economic analysis which is conducted by means of a total cost of ownership (TCO) model.
MODULAR CHASSIS SPECIFICATIONS
The key design specifications for electric buses are defined in terms of their battery capacity, range, life, charging time, and seating capacity, as per the segment’s requirements. The picture of the modular chassis depicts the modular platform developed by FEV for e-buses ranging from 6 metres to 12 metres.
E-BUS SOLUTIONS OFFERED BY FEV
FEV’s solutions for the e-bus segment involves a modularitybased EV chassis platform, which can serve a wide range of buses. The chassis frame can be used for buses measuring anywhere between 6 metres and 12 metres in length which can only change with the frame rails within the modularity of the defined cross members.The modular chassis allows the design of the frame, system layout, technical specifications as well as the requirements of all major aggregates for any bus variant to remain the same, albeit with minor tuning.
To meet customer-centric performance attributes like vehicle acceleration, gradeability, range, and thermal management, the maximum torque, power, and battery capacity specifications of the traction motor have been defined by FEV’s robust design calculations and simulation program. It also ensures UBSII (Urban Bus Specification) requirements in respective domains.
Not just for the traction motor, FEV also considers multiple loads for battery capacity and sizing finalisation. The company ensures that only a specified battery size is sufficient to offer best-in-class vehicle range under all operating conditions.
As regards modularity ofthe e-bus platform for different commercial vehicle applications, having developed a modular chassis frame for electric buses, the very same platform, with certain modifications, can also be converted to suit different sizes of commercial vehicles.
SCOPE OF IMPROVEMENT
Electric buses have significant room for improvement in terms of the weight and noise reduction to achieve a better range, lower operating costs, and optimised passenger experience. These targets can only be met by using lightweight body and chassis materials and relying extensively on a system-optimised electric-drive propulsion system.
In terms of lightweighting solutions, FEV is targeting maximum reduction of the vehicle mass. An aluminum bus body structure along with selected aluminum cross members in the optimal design structure will be a major contributor to achieve a lightweight structure of an e-bus. The chassis frame FUPD (front underrun protective device), RUPD (rear underrun protective device) and SUDP (side underrun protective device) are also converted into aluminum designs.
FEV also makes use of composites along with aluminium for designing the bus floor structure, therefore additionally contributing to the overall weight reduction of the vehicle. On the other hand, the bus body and chassis comprise of ultra-high strength stainless steel.
Lightweighting also enables significant optimisation of allied vehicle dynamics systems including the suspension, wheels, brakes, as well as the vehicle propulsion systems. The completely new design will be 15% to 30% lighter than today’s standard e-bus architecture and will achieve cost savings in the range of 5% to 15 % compared to the standard bus body.