Controlled Power Technologies (CPT) is developing a 48-volt version of its 12 volt electric supercharger based on its variable torque enhancement system known as VTES. (Earlier post.) The higher-voltage variant will support moves by European vehicle manufacturers announced earlier this year to introduce 48 volt passenger vehicle power networks to help meet the requirement for lower fuel consumption and CO2 emissions.
At 48 volts, a VTES electric supercharger will transform 7kW of battery power into a highly boosted charge of air for downsized gasoline and diesel engines. Unlike crankshaft-driven superchargers and exhaust-gas-driven turbochargers, an electric supercharger is mechanically decoupled from the engine, meaning it can deliver the air almost instantaneously into the engine—spinning up to 70,000 rpm in less than a third of a second.
Even with the higher transmission gearing adopted by manufacturers to reduce CO2 emissions and particularly at the lowest engine revs, the instant additional torque when the driver needs to accelerate these smaller powertrains from low engine speeds is already very beneficial at 12 volts.
Electric supercharging at 48 volts extends that envelope of torque enhancement. It’s an efficient way of using 7kW of stored electrical power to deliver not less than six times that at the crankshaft. In other words adding a useful 42kW boost for low speed overtaking and hill climbs. Depending on the turbocharged engine system optimisation the boost could be as much as much as 70kW or 10 times the instantaneous power extracted from the batteries or supercapacitors.
The torque response of these future VTES equipped vehicles will be equivalent to the best mass market vehicles on the road today. There will be no torque deficit or other tradeoffs from essential engine downsizing and higher gearing, which now dominates the development of internal combustion engines. If anything their low speed performance will be even better, while still delivering very significant fuel economy benefits and CO2 reduction.—Guy Morris, CPT’s engineering director and chief technical officer
Micro-mild hybrids. CPT argues that currently the most cost-effective solution for reducing CO2 emissions is modular micro-mild (MM) hybrid technology, based on highly boosted and radically downsized gasoline and diesel powertrains. For further CO2 reduction and economies of scale the automotive industry should also press ahead with the standardization and implementation of the proposed 48 volt vehicle power network being championed by some European vehicle manufacturers.
CPT foresees a new generation of MM hybrid vehicles with radically downsized engines featuring transient electric boosting as a more effective hybrid alternative to the mechanical supercharging and/or twin turbo-charging systems in use today.
For a 15-25 percent reduction in CO2 emissions using micro-mild hybrid technologies we have established an incremental cost to the manufacturer of between €750 and €1500. This compares favorably with the 8-20 percent typical of CO2 emissions benefit offered by mild hybrids, full hybrids and plug-in hybrids, at a much higher manufacturing on-cost of between €1,600 and €10,000.
Our modular technology is very scalable and also well suited to higher voltages, but currently the most customer benefit is delivered through the optimisation of micro-mild systems. CO2 reduction across a manufacturer’s entire vehicle range requires a comprehensive strategy, and this means delivering customer value in all segments of the car market.—Guy Morris
LC Super Hybrid technology demonstrator. CPT’s production-ready VTES technology has already been incorporated as a 12 volt system in its LC Super Hybrid technology demonstrator. The company has commissioned AVL to build the demonstrator, which is currently undergoing final shake-down trials in Austria in readiness for evaluation by vehicle manufacturers. Following this initial assessment by carmakers, the vehicle will then be re-built with a 48 volt electrical system. The project is being supported and funded by the Advanced Lead Acid Battery Consortium (ALABC).
The demonstrator will improve significantly on the energy efficiency of a gasoline-engine variant of the VW Passat. With performance similar to that of the 1.8 TSI and 2.0 TDI models, but even lower CO2 emissions and fuel consumption than the current production 1.4l TSI BlueMotion model, the CPT/ALABC demonstrator will provide carmakers with real world confirmation of the potential for this new class of MM hybrid vehicle, according to CPT.
The MM hybrid concept, which was first proposed at the AVL conference a year ago, combines CPT’s modular VTES electric supercharger and SpeedStart stop-start technologies in a state-of-the-art yet affordable family sized vehicle. The LC Super Hybrid validates that concept and will demonstrate significantly reduced CO2 emissions combined with excellent performance at relatively low cost compared to full hybrid and range-extended or plug-in HEVs. ALABC carbon-enhanced lead-acid battery designs complement the low voltage technology helping to maximise energy recuperation during deceleration, fully realizing the potential in our stop-start and engine boosting technologies by enabling high power generation and electrical energy recovery as well as outstanding torque response.—Guy Morris