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News and Library > news 2009 > IP leads TSB supported consortium > IP leads TSB supported consortium to develop a modular low cost hybrid powertrainDate: 13/10/2009Potential breakthrough in hybrid system costs could lead to high volume applications New modular approach offers highly effective hybrid solution for mainstream applications with low investment, low risk and minimal impact on existing vehicle hardware. Widespread adoption of hybrid technology has been held back until now by the high investment and piece costs involved, coupled with uncertainty over future demand. To help address these challenges and make hybrid systems commercially viable for high volume application, a consortium led by powertrain engineering consultancy Integral Powertrain is developing a modular hybrid system that offers a technology ladder from micro hybrid to full plug-in hybrid electric vehicle (PHEV) while minimising investment in either new hardware or new vehicle architecture. Integral Powertrain’s partners in the project include Jaguar Land Rover, electronics specialist Smart Power Solutions and transmission specialist Drive System Design. Funding has been provided as part of the Technology Strategy Board’s Integrated Delivery Programme by both the Department for Transport and the Technology Strategy Board. Work on the Ultra Cost-Efficient Hybrid Powertrain (UCEHP) project began in July 09, based around a conventional transverse engine and gearbox layout. In the first step, for micro hybrid applications, the consortium uses Integral Powertrain’s variable ratio (VR) crankshaft pulley and high efficiency brushless permanent magnet B-ISG (Belt Integrated Starter Generator) to provide stop-start capability that is substantially improved over existing micro hybrids. “The VR pulley allows the use of a lower torque motor for a given engine size and permits cost effective, refined and extremely fast stop-start operation even with large diesel engines,” explains Integral Powertrain technical director Luke Barker. Compared to other B-ISG micro hybrids, this system has a lower overall cost because the on-cost of the VR pulley is more than compensated for by significant savings in the motor, motor drive, electrical storage and FEAD (front end accessory drive) systems resulting from the lower torque requirement. The second step towards full hybridisation requires only the upgrading of the on-board electrical storage capacity to enable air conditioning use while the engine is stopped; achieved by the B-ISG driving the compressor while the VR pulley freewheels on the crankshaft. Use of the B-ISG in this way provides a much lower cost alternative than an electric air conditioning compressor, potentially saving hundreds of Euros per vehicle. The relatively high power ISG machine combined with the increase in electrical storage capacity also increases the potential for regenerative braking. “Typical CO2 savings for this configuration are 8-10 percent on the NEDC test,” advises Barker. Full hybrid functionality is achieved by the addition of a second brushless permanent magnet traction motor integrated with a conventional low cost AMT (automated manual transmission) and a further upgrade in battery capacity. Active control of the two electrical machines endows the simple AMT with enhanced gear shift quality and provides rapid and refined transition between different operating modes because the high power ISG allows the necessary control of engine speed; a key feature that is not apparent in other systems. The hybrid capabilities include electric-only drive at light load/low speed conditions and improved regenerative energy recovery. Compared to conventional powertrains, this arrangement has been shown to offer typical CO2 savings of 25-30 percent. Barker continues, “The UCEHP strategy allows conversion of existing low cost powertrains to full hybrid capability with minimal impact on proven hardware or vehicle architecture, dramatically reducing development risk and both engineering and capital investment.” The consortium program will address the engineering of all key sub-systems together with the control strategy covering battery management, IC engine and electrical machines. In particular, detailed simulation will be employed to optimise cost to benefit ratio and to ensure refined gear shifting and mode switching. First hardware will be on test in Q2 2010. “This technology promises three key benefits: a cost effective electric ancillary drive, super fast engine restart performance and the means whereby a low cost AMT with a single dry clutch can provide similar functionality to the expensive CVT power split transmissions seen on current hybrid vehicles,” concludes Barker. This article has an associated document, click here to download - IPT6165 UCEHP release draft final approved 8-10-09.pdf |