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Posted on February 24, 2015 by  & 

CPT sees rapidly growing interest in 48V mild hybrid technology

Environmental award winner Controlled Power Technologies (CPT) witnessed more interest in 48V mild hybrid vehicles when it recently showcased its switched-reluctance (SR) motor-generator technology in Los Angeles.
"Hybridisation at 48V provides a cost-effective near term alternative to full hybrids and pure electric vehicles, which at present are more expensive to produce," said CPT's vice-president Taylor Hansen, who joined the low carbon technology developer in September and attended the SAE conference to exhibit the company's products. Taylor has commercial responsibility for CPT's North American operations based in Detroit.
"There was lots of interest from international automakers and their powertrain suppliers," said Hansen commenting on a significant shift by the automotive industry towards more affordable low voltage electrification of the powertrain. "At a nominal 12V standard (14V charging at 300A) the industry is stuck with about 3kW from a motor-generator when you adjust for high current losses, which constrains the electrical power and torque available and, of equal importance, any kinetic and thermal energy recovery. However, with a nominal 48V grid (42V charging at 300A) the industry has access to approximately 12.5kW, which makes all the difference to powertrain efficiency and performance, while the DC voltage remains well below the safety critical 60V level."
Hansen is focused on bringing to market CPT's portfolio of electronically controlled electrical machines known as COBRA, SpeedStart and TIGERS. Each product achieves significant CO2 and NOx reduction through different applications of switched reluctance technology, which as an added bonus eliminates the need for permanent magnets and rare earth metals in an electrical machine.
CPT's COBRA (COntrolled Boosting for Rapid response Applications) technology is an electric supercharger developed for commercial vehicle and off‐highway applications capable of delivering 170 litres (45 gallons) of air a second into the engine It's particularly beneficial for example in urban bus and truck operations with their unremitting stop‐start duty cycles, and for reducing diesel tailpipe emissions.
SpeedStart is an advanced motor‐generator system tested continuously for more than two-and-a-half years to an industry leading 2.5 million stop‐starts, meaning that it's now ready to validate for production applications. The technology offers a high level of NVH refinement as well as additional 48V functionality with excellent controllability, thermal management and robustness. Functionality includes torque assist for launch and low speed transient acceleration, optimised motorway cruise conditions with electric assist 'load point moving' and a leaner fuel calibration, in‐gear coast‐down, and the ability to harvest significant kinetic energy from regenerative braking.
The TIGERS turbine integrated gas energy recovery system is a complementary application of CPT's switched reluctance technology providing cost‐effective energy recovery from exhaust gases with their significant mass flow rates. TIGERS consequently is also an effective means of supplementing or replacing an existing alternator.
USA joins the 48V hybrid European bandwagon
In 2011, at the 15th Automobil Elektronik Kongress in Ludwigsburg, Audi, BMW, Daimler, Porsche and VW made the ground-breaking announcement that they would instigate a 48V standard known as LV148 for their vehicles' on-board power networks - a sea-change not seen in the industry since the 1950s when carmakers moved progressively from 6V to 12V.
Among the first to develop practical technical solutions, CPT first noticed a growing interest in the USA in 48V mild hybrid technology about three years ago. Last year it had the opportunity to ship the world's first 48V hybrid demonstrator, developed under its LC Super Hybrid programme, together with its 12V sibling fitted with otherwise identical motor generator technology (demonstrating best-in-class stop-start capability) from its UK headquarters for a series of ride-and-drive evaluations by powertrain development engineers employed by US-based car and truck makers.
"The industry has solutions for full hybrid and pure electric vehicles, but currently such powertrains remain expensive, and hydrogen fuel cell vehicles even more so," says Hansen. "Moreover, 85 per cent of global electricity currently distributed via national grids still comes from coal fired power stations, so even if the tailpipe emissions are zero there is considerable CO2 emissions overall. Similarly, hydrogen is still produced predominantly from hydrocarbon fuels. Technology road maps suggest this will improve through a combination of EV economies of scale, more advanced battery chemistries and more grid electricity from renewable sources."
"Meanwhile, we need immediate and cost-effective solutions for reducing CO2 and NOx emissions to meet legislative demands and the imminent WLTP test cycle," says Hansen. "It's the relative ease of manufacture and affordability of 48V mild hybrids for the motorist, combined with their efficient use of gasoline and diesel fuels that makes them so attractive to car makers globally."
"CPT's contribution to this medium term solution is the development of highly controllable motor-generator technology applicable to a wide range of vehicles produced by car, bus and commercial vehicle manufacturers," says Hansen. "For the motorist SR technology can deliver a 30 per cent improvement in fuel economy for a premium of less than $1,000. This is significantly less than the additional cost of high voltage hybrids, which currently can add $8,000 to the sticker price. And it's less than one-tenth the premium for plug-in hybrids and pure electric vehicles, which currently can add up to $15,000 to the price on the forecourt."
"We see rapid growth in 48V mild hybridisation and it's easy to see why," says Hansen. "Compared with 200V to 600V full hybrid and battery electric vehicles, the low voltage approach avoids the need for high cost safety features and large battery packs. Furthermore, the universal application of this technology to the more than 100 million vehicles per annum forecast to be produced from 2020 onwards, 98 per cent of them with gasoline and diesel engines, would in the short term reduce annual CO2 emissions by 100 million tonnes globally per annum (50g/km reduction x 20,000km average annual mileage per vehicle x 100 million vehicles). And the technology is relatively easy to homologate for production, which buys the industry more time to develop lower cost pure electric and hydrogen fuel-cell vehicles."
Not surprisingly there was substantial discussion at the Hybrid & Electric Vehicles Technologies Symposium on battery electric vehicles and hydrogen fuel cells. On its website promoting the event, however, the SAE has similarly recognised the growing relevance of low voltage electrification as an immediate medium term solution by promoting Kevin Layden from Ford with his scheduled presentation on 'the strategic outlook of electrification' recognising that global emission regulations are becoming more and more stringent with every passing legislation.
In its preamble the SAE commenting that 'to meet these requirements, OEMs are turning to electrified powertrain technologies. But with many levels of electrification - from minimal electrification as in the 12V start/stop application to an electric-only powertrain of the BEV - each variant of electrification has different levels of acceptance by the typical customer. The main challenge facing the OEMs is to put forth a portfolio of electrified vehicles that not only satisfy the regulatory requirements, but also are acceptable to the mainstream customer and do all this profitably.'
The SAE similarly stimulated interest in Veerender Kaul from Frost & Sullivan with his scheduled presentation on 'US Consumer Perceptions and Preference for Powertrain Systems and Technologies' commenting that 'determining cost effective approaches and technologies to simultaneously meet the progressively higher Corporate Average Fuel Economy (CAFE) standards as well as changing customer needs and tastes is a key challenge for vehicle manufacturers.'
The SAE promotional material also endorsed Mazen Hammoud from Ford with his presentation on 'Mild Hybrid and Enablers for Fuel Economy Features' commenting that 'global regulatory changes, coupled with customer wants, are driving the need for various levels of electrification of powertrains. Depending on the customer drive cycle, mild hybrids operating at 48V may provide an optimal cost-benefit solution.'
"In frequent discussions with our customers, we see 48V mild hybridisation as a key growth area for the industry in the medium term," says CPT's chief executive Nick Pascoe. "It can cost-effectively deliver the 2.5 per cent year-on-year reduction in fuel consumption and CO2 emissions required by legislators without loss of vehicle performance and with a manufacturing investment the industry and its customers can actually afford. It also provides the industry with a useful breathing space while it awaits a breakthrough in affordable hydrogen energy storage and distribution, and more widely available renewable energy from our national grids."
International cooperation and technology partners
Working closely with many international automotive companies, CPT has been in the vanguard of hybrid vehicle innovations since the day it was formed, and was one of the first in the automotive industry to spot the opportunity for low voltage electrification of the power train.
Technology partners include the European Advanced Lead-Acid Battery Consortium (EALABC), which has co-operated though the application of advanced lead-carbon batteries. Not only can this breakthrough battery chemistry be 100 per cent recycled just like traditional lead-acid batteries, but lead-carbon batteries with their integrated super-capacitance have the ability to meet the high-rate partial state-of-charge (HRPSoC) requirements of a mild hybrid. In other words, they can remain permanently half charged for the life of the vehicle, which is exactly what's required in a mild hybrid when constantly transferring joules of electrical energy in and out of the battery.
"It's like a leaky bucket that is always half full yet always being topped up," says Hansen. "The leaks represent the flow of energy to 48V motor-generators for power and torque assist of a combustion engine. And the constant topping up represents the flow of energy from recuperative braking and exhaust gas driven generators."
Unlike Li-ion chemistry, these high power lead-carbon batteries can operate at low temperatures, and because 1kWh is ample for a mild hybrid they can be similar in size to conventional starter-motor batteries. Being compact they package easily into a vehicle. They are also ideally suited for next generation hydrogen fuel-cell vehicles, taking the example of the recently launched Toyota Mirai which has a 1.5kWh NiMH battery. Full hybrids and pure electric vehicles on the other hand require at least 24kWh of actively cooled batteries, which means that complete battery packs are heavy and expensive even when light elements from the periodic table such as lithium are used in their construction.
CPT's other technology partners include powertrain developer and systems integrator AVL, based in Austria, Germany and the USA, which alongside the London-based EALABC has been significantly involved in CPT's LC Super Hybrid programme. Other international companies include belt tensioning specialist Mubea from Germany, and Provector, a leading expert in battery management systems, also based in the UK.
CPT is also part of a consortium that worked previously on the successful Ricardo led 24V HyBoost project, which delivered a breakthrough in gasoline fuel efficiency and CO2 reduction through a similar concept of low voltage hybridisation of the power train.
CPT's technology partners for the more recent Advanced Diesel-Electric Powertrain project known as ADEPT, which again is led by Ricardo, include ELABC, Faurecia Emissions Control Technologies, Ford and the University of Nottingham. The ADEPT project aims to apply the low voltage concept of 'intelligent electrification' for the first time to a diesel car in a project supported by the UK's innovation agency InnovateUK previously known as the TSB (Technology Strategy Board).
CPT has also worked previously on gas exhaust energy recovery with the University of Nottingham and Ford in the TSB co-funded 'Vehicle Integrated Powertrain Energy Recovery' project known as VIPER led by Jaguar Land Rover joined by BP, IAV and Imperial College London.
IDTechEx comments that 48V systems for conventional on-road vehicles offer greater efficiency and functionality now appropriate equipment is available and affordable. Within this, adding energy harvesting alternators that provide torque assist with nothing more than an advanced lead-acid battery is a significant advance. It does not make it an electric vehicle because the motor never drives the wheels on its own but it is a valuable transition product and a reason why IDTechEx does not forecast EV road vehicles being dominat in 2025 though they will take a large market share. For more see Electric Vehicle Forecasts, Trends and Opportunities 2015-2025
Source and top image: Controlled Power Technologies
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