he convergence of global standards for fuel economy and CO2 emissions means that the auto industry will need to embrace exhaust gas energy recuperation as well as kinetic energy recovery by electro-mechanical means as the next major step for CO2 reduction,” says Nick Pascoe chief executive and chief technology officer at Controlled Power Technologies. Speaking on the eve of the Engine Expo international trade fair for automotive powertrain design and technology held at Novi in Michigan he commented. “Energy recuperation is the key to ground-breaking solutions that the motorist can afford and this has caused the industry to re-visit the previously mooted higher than 12 volts, but less than 60 volts, electrical architecture. Mild electrification deploying a proposed 48 volt standard will be a major factor for enabling the required motor-generator efficiency and power levels.”
Pascoe says the industry has reckoned the additional cost to the motorist to achieve the required 30 per cent reduction in CO2 emissions is estimated at $1,500 for a family sized saloon. This is significantly less than the $7,500 US federal subsidy for electric vehicles; an on cost that would seem to remain unavoidable unless there is a significant breakthrough to reduce battery cost.
CPT gained significant prominence and credibility in the industry last year when it sold its VTES electric supercharger business in December 2011 to Valeo for £30 million. An elite team of automotive engineers, originally established in the UK by Ford then Visteon, had worked on the technology for more than 10 years. With extraordinary vision their switched-reluctance motor-generator technology was developed from the outset to be scalable to higher voltages. The choice of a switched-reluctance electrical machine was also carefully researched.
CPT is similarly focused on bringing its closely related Cobra, SpeedStart and Tigers technology to market readiness. Cobra is a water cooled electric supercharger for commercial vehicle and off highway applications. SpeedStart is a powerful water cooled starter-motor and generator able to provide torque assist to the engine and harvest kinetic energy. Tigers is a water cooled turbine integrated gas energy recovery system.
“Automakers have a broad palette of hybrid technology options,” says Pascoe. “Some however are more expensive than others. Mild and full hybrid vehicles including plug-in hybrids, for example, operating between 200 and 600 volts, incur significant additional development and product costs to the automaker, which then have to be passed on to the consumer or absorbed by the OEM; hence the need for governments to subsidise electric vehicles. Consequently such hybrid and electric vehicles are unaffordable for most motorists even with government subsidies.”
The recuperation energy potential of a downsized gasoline engine equipped with a powerful water-cooled starter-motor and generator is significant says Pascoe. At 48 volts SpeedStart is able to provide torque assist to the engine for acceleration, reduce fuelling during cruise conditions, and harvest kinetic energy during braking. Brake energy alone is worth more than 60kJ/km accumulated over the New European Drive Cycle and is just waiting to be harvested.
“Not only does 48 volts provide a solution for more efficient powertrains, but also for meeting other increasing vehicle energy demands already exceeding the capabilities of a 12V/3kW alternator. This includes electrically powered cooling fans, water pumps, and electric power assisted steering – all part of hybridisation - as well as improving passenger safety, security and comfort systems. These higher power electrical devices would all benefit from higher voltage systems. However, increasing the voltage beyond 60 volts requires much greater safety consideration leading to a significant increase in cost. The specification for 48 volts is still evolving, and there may yet be more than one, but there is real pressure from global automakers to conclude the specification as quickly as possible,” says Pascoe.
Already developed for 12 volts, the CPT SpeedStart system is a powerful belt-driven starter-motor and generator with its control and power electronics fully integrated into the liquid cooled device. It’s also the world’s first liquid cooled switched reluctance motor-generator developed for automotive stop-start. Switched reluctance machines have the benefit of eliminating increasingly expensive rare earth materials used in permanent magnet motors, which currently predominate throughout the industry for alternators, conventional starter motors and first generation stop-start systems.
The CO2 and fuel economy benefits of 12 volt based stop-start combined with SpeedStart’s efficient high current electrical generation and regeneration can be as much as 20 per cent. The driver benefits also include its high torque fast response, leading to a more desirable and comfortable stop-start with a unique ‘Driver Change of Mind’ capability to ensure that its operation is not intrusive to normal driving styles. The availability of this market ready technology is expected to be in the next generation of cars reaching dealer showrooms in 2015.
Meanwhile, CPT anticipates having a 48 volt SpeedStart technology demonstrator running in 2013. Bench testing has indicated an increase in transient performance to 10kW of generation power, depending upon system specification. And the motoring power through direct torque assist to the engine has similarly increased, though duration becomes a critical parameter. The engine breakaway torque at zero rpm can also be increased to 95Nm – enough to start even large automotive engines.
“A combination of electric launch assist, quasi-continuous electric motoring for fuelling optimisation, and energy recuperation with electric brake assist not only has a measurable impact on NEDC emissions but offers significant real world fuel economy,” says Pascoe. “However, this additional benefit can only be achieved at 48 volts. Compared with our 12 volt LC Super Hybrid technology demonstrator based on a VW Passat 1.4 litre TSI model it would further reduce the CO2 emissions by 4 to 8 per cent, depending upon drivability targets, and the 0-60mph acceleration further reduced from nine seconds. And this is for a large family saloon weighing 3,200lbs (1,450kg) with a small 1.4 litre gasoline engine delivering 42mpg US (50mpg imperial) fuel economy in our 12 volt demonstrator with performance already equivalent to a 2-litre turbocharged diesel engine costing at least $3,000 more.”
CPT will also next year secure the first vehicle installation of its turbine integrated gas energy recovery system known as TIGERS in a UK government Technology Strategy Board (TSB) co-funded project. The ‘Vehicle Integrated Powertrain Energy Recovery’ project known as VIPER will build on CPT’s involvement in the Ricardo-led ‘HyBoost’ programme, which was similarly part funded by the TSB. The VIPER project aims to develop more thermally efficient engines and technologies for thermal energy recovery. The programme objectives will show how this can be achieved over a broad range of vehicles in part by optimising the control of heat energy from gasoline and diesel engines. The VIPER project explores several technologies for recovering energy otherwise lost as waste heat, and is being led by Jaguar Land Rover. Other consortium members include Ford, IAV, BP, Dana, the University of Nottingham and Imperial College London.
CPT is already successfully running TIGERS on an engine dynamometer at 650 degrees centigrade, which is close to the engine exhaust temperature of 800 degrees in a running vehicle. The TIGERS system has a generating efficiency of more than 70 per cent and a maximum operating speed of 63,000rpm. The liquid cooled generator is targeted to recover 2-4kW from an engine’s hot exhaust gases. For a comparison with energy recuperation from electric brake assist this is equivalent to SpeedStart recuperating 40-75 per cent of the braking energy generated during an NEDC test.
The VIPER programme will compare the TIGERS installation with thermo electric generators (TEGs) where power levels and system cost remain major issues. The TIGERS-V platform will also be used in the programme to develop a sensing system; a stator and rotor design for continuous steady state operation; low pressure ratio high efficiency turbine optimisation; and bypass system design and development.
CPT’s low cost solutions for CO2 reduction are being exhibited this week at the Engine Expo at the Suburban Collection Showplace in Novi, where the company will be presenting its technology on booth E218. The show runs from Tuesday to Thursday 23-25 Oct.
In addition, CPT’s 12V demonstrator is being shipped to the US for evaluation by US automakers and will also be presented at the Battery Show next month at the same exhibition venue in Novi. The car will be displayed by Exide Technologies, which has supplied the advanced lead-carbon batteries. Representing the state of the art in affordable CO2 reduction, the LC Super Hybrid was first unveiled at the 2012 Geneva International Motor Show. The technology demonstrator is helping to define a whole new class of low cost micro-mild hybrid vehicles. The car has been developed in cooperation with the Advanced Lead-Acid Battery Consortium, an international research group based in the US in North Carolina, which has funded the vehicle and is also exhibiting at the Battery Show.
Based on a series production 1.4-litre turbocharged VW Passat TSI model - generally considered an industry benchmark for fuel economy in this size of vehicle - the LC Super Hybrid is already providing carmakers with real world validation of CPT’s pioneering and innovative technical achievements. The technologies comprise a VTES electric supercharger, SpeedStart belt-integrated starter generator with an advanced belt tensioning system, new PbC lead-carbon batteries, which avoid the need for higher cost battery technologies or super-capacitors, and higher gear ratios to reduce engine speed.
Recalibration of the engine increases power from 122 to 142PS and torque from 200 to 275Nm. This power and torque is comparable with VW’s bigger 1.8-litre TSI gasoline engine, which delivers 160PS and 250Nm, and the engine output of the LC Super Hybrid is generally equivalent to vehicles in the 2-litre class. Despite the enhanced gasoline engine performance the vehicle achieves near diesel levels of fuel economy, but with substantially lower production costs.
The impressive performance and excellent fuel economy are underscored by the acceleration figures and results measured on the standard European drive cycle. The LC Super Hybrid delivers CO2 emissions of less than 130g/km compared with 140g/km for the baseline Passat 1.4-litre TSI, which is already best in class, and an even more significant reduction when compared with 160g/km for the equivalent performance 1.8-litre TSI model. This represents a reduction in CO2 emissions of 8 and 23 per cent respectively. Similarly, the excellent fuel economy of 5.6 litres/100km (42mpg US/50mpg imperial) represents a significant 11 and 24 per cent improvement respectively when compared with 6.2 litres/100km (38mpg US/46mpg imperial) for the 1.4-litre TSI and 6.9 litres/100km (34mpg US/41mpg imperial) for the 1.8-litre TSI also measured over the NEDC drive cycle.
The technology incorporated into the LC Super Hybrid, which has taken 10 years of research to develop, has achieved its technical breakthrough in the cost effective reduction of CO2 emissions and fuel consumption without compromising the fun-to-drive factor and high energy density fuel tank range advantage of gasoline engines. The demonstrator embraces low voltage switched reluctance (SR) motor-generators, which are not currently employed by the automotive industry in mass production. The motors are of simple robust construction using steel, aluminium and copper and avoid the use of increasingly expensive rare earth materials required for permanent magnet motors. The SR technology is licensed from Nidec Corporation of Japan, one of the world’s leading suppliers of electric motors.
Controlled Power Technologies (CPT) is an independent, award winning, clean-tech company specialising in the development of cost-effective CO2 reduction measures for the global automotive industry that avoid major redesign of the powertrain or vehicle electrical system. Its core competencies include low voltage power electronics, advanced control software and the application of low voltage electrical machines to vehicle powertrains. The company is a spin-off from the advanced powertrain development team established in the UK more than 10 years ago by Visteon, a spin out from Ford, when electric supercharging and switched reluctance motor technology was first mooted, and its technology development partner Emerson Corporation, whose motor business has since been acquired by Nidec. CPT was established in 2007 as a management buy-in funded by venture capital to acquire this advanced powertrain business. The company comes with a highly experienced team of automotive engineers and is backed by a number of prominent investors specialising in the energy and environmental sectors.