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UK-based Aeristech has introduced a new 48V electric supercharger capable of continuous operation at high boost levels. Independently validated by Ricardo and MAHLE Powertrain UK, the technology provides greater efficiency and easier packaging than a mechanical supercharger or a two-stage turbocharger.
Aeristech said it overcame the thermal management issues that can restrict other electric boosting devices currently available on the market to only transient operation by using permanent magnet motor technology in place of the more usual switched reluctance type. This has been made cost-effective by developing a patented control and switching technology that enables the use of many cost-competitive components.
Aeristech’s 48v eSupercharger has already been demonstrated by MAHLE Powertrain UK in a D-segment appraisal vehicle using its downsized turbocharged 1.2 liter, 3-cylinder gasoline engine. The engine achieved 32.9 bar BMEP at 2000 rpm (+10% over base), delivering 313 N·m (231 lb-ft) and a maximum power output of 193 kW (259 hp)—an increase of 61% over the base engine.
At low speed (1250 rpm), the eSupercharger achieved 28.6 bar BMEP—an increase of 43% over the baseline 20 bar BMEP in the Mahle engine.
Analysis of the power curve showed that the turbocharger run up line was complete by 3000 rpm, resulting in poor low-speed driveability. The addition of the eSupercharger re-instated the low-speed torque. In other words, combining the eSUpercharger and the turbo resulted in a continuous torque curve through the complete engine operating range.
Our system can deliver over 2.5 bar of boost pressure continuously, setting it apart from other systems which only offer short duration boost assist for improving the engine transient response. By using a 48V architecture, we have provided a solution that is easily implemented and competitive in cost for the growing numbers of hybrid and mild-hybrid vehicles that will be launched in the next few years.
By replacing the smaller turbo in a two-stage turbocharging arrangement with our eSupercharger, MAHLE Powertrain UK was able to increase the size of the main turbo without concerns over driveability and transient response. The eSupercharger can not only help increase specific output but is also much easier to accommodate within the engine compartment than a second stage turbocharger because it has greater layout flexibility.—Aeristech CEO Bryn Richards
In a separate program using WAVE simulation, Ricardo carried out detailed modeling of a 221 kW (296 hp) 2.0-liter gasoline engine with a single-stage turbocharger. Adding a 48V Aeristech eSupercharger enabled the turbine to be increased in size by 80%, improving BSFC (Brake Specific Fuel Consumption), torque and transient response throughout the engine speed range. Ricardo concluded that without the eSupercharger only a larger engine could have met the requirements, if relying on a conventional single-stage turbocharger.
Using an eSupercharger also has advantages for emissions control. Because it is applied to the inlet side of the engine, it reduces the thermal mass in the exhaust stream which helps to maintain catalyst temperature, especially at lower speeds and loads.
Aeristech’s motor control strategy separates commutation and power control. This approach dramatically reduces the cost of many key switching components while ensuring exceptionally accurate high-transient speed control.
The IGBT/MOSFET switches controlling power use a different time constant to the switches handling commutation. The switching frequency is no higher than the running speed, this allows for very accurate transient control of the motor.
This patented control architecture delivers a controller efficiency in excess of 95% with low internal switching frequency and low-cost internal components. Aeristech’s motors are designed for higher speeds and lower internal impedance than would be possible with conventional controllers. Aeristech’s motors are capable of running continuously with high power output.
By achieving high operating speeds, Aeristech’s compressors offer wide and efficient compressor maps and high boost pressures. The motor has class-leading power density and low inertia. The eSupercharger operates at up to 150,000 rpm with a transient response of idle-to-target speed in under 0.4 seconds.
Aeristech is a British clean technology innovation business founded around an innovative permanent magnetic switching architecture that has enabled it to produce what it says is the most power dense electric motor of its type currently available. This core technology forms the basis of the company’s range of products, which include an electric supercharger, full electric turbocharger, fuel cell air compressor and turbine generator.
As a one-stop-shop for electrically driven pressure charging solutions, Aeristech designs, tests and develops every aspect of the system, from the bearings to the compressor wheel, to suit the customers’ individual application. The company is working with vehicle manufacturers and suppliers to licence innovative proprietary technologies to reduce tailpipe emissions, increase fuel efficiency and heighten driving characteristics of the next generation of ‘right-sized’ diesel and gasoline engines.
Daimler reports that the two-year eMERGE real-world trial of 146 smart fortwo electric drive vehicles has been completed. Those taking part in the project were private and business customers in Berlin, Potsdam and North Rhine-Westphalia. The lowest average energy consumption per vehicle over one year was 10.4 kWh/100 km, while the longest single-charge range was 161 kilometers (100 miles). The smart fortwo electric drive is certified with a consumption of 16.3 kWh/100 km and a range of 145 kilometers (90 miles).
eMERGE is being followed directly by eMERGE2, which will see up to 200 cars being used in the model regions of Berlin/Potsdam, Stuttgart, Rhine-Ruhr and Rhine-Main. The vehicle fleet will include the battery electric B 250 e and plug-in hybrids from Mercedes-Benz. The different technology and vehicle segments suggest different use cases than the smart fortwo electric drive.
The inclusion of plug-in hybrids allows the project partners to study the usage patterns of a further group of customers and to compare them with those of customers with all-electric vehicles. In this way, the findings from real-world customer use in eMERGE2 can, in turn, be pooled with other empirical data—such as from endurance trials—and be incorporated into the development of electric drivetrains and systems.
eMERGE. Derived from “Electric Mobility Model Regions”, eMERGE evaluated usage, charging and marketing models of electric mobility based on real customer data from the Rhine-Ruhr and Berlin regions. eMERGE had seven cooperation partners: Daimler AG; Fraunhofer Institute for Open Communication Systems (FOKUS); PTV AG; RWE Effizienz GmbH; RWTH Aachen University (Chair of Management Accounting); TU Berlin (Faculty of Economic and Infrastructure Policy/WIP); and the University of Siegen (Chair of Marketing). eMERGE was sponsored by the German Federal Ministry of Transport and Digital Infrastructure (BMVI) within the framework of Electric Mobility Model Regions.
The broad-based field trial within the framework of the eMERGE project provided information on user behavior and e-car technology and also studied intelligent charging systems for improving the utilization of the power supply as well as various pricing systems with regard to customer acceptance.
Based on transport models, the project partners examined the need for a publicly available charging infrastructure. Within the project Daimler was responsible for collecting the driving and charging data required for evaluation of the field trial. Data such as charging time and charging frequency were collected anonymized and scientifically evaluated; there were also regular interviews with the participants.
The participants in the eMERGE research project have made a key contribution to the mobility of the future. With their assistance, we have scientifically investigated the real-world customer use of electric cars and thereby obtained valuable data to help us develop future electric cars.
Increasingly low-cost battery systems will enable us to offer our customers ever more attractive prices in future. However, we also advocate an attractive system of incentives capable of giving a quick boost to electric mobility. Daimler already offers the world's most diverse fleet of electric and hybrid vehicles and is continuing to invest heavily in the development of alternative drive systems.—Harald Kröger, Head of Development Electrics/Electronics & E-Drive Mercedes-Benz Cars
Alongside the Mercedes-Benz plug-in hybrid initiative, which envisages a total of ten models by 2017, the company is also planning further all-electric vehicles powered by either battery or fuel cell.
eMERGE study. Among the findings of the eMERGE analysis were:
The typical supporter of electric mobility is educated and tech-savvy with an above-average income.
The less an interviewee knew about electric mobility, the more negative was his or her opinion or electromobility.
Purchase price is a key criterion for or against an electric car; on the other hand, interviewees were often unaware of consumption savings.
The ideal target group in the study were commuters who drove a daily distance of 50 kilometers (31 miles) or more, because this then makes the purchase of an electric car financially attractive owing to the low operating and maintenance costs.
The interviewees also attached very great importance to range, performance, space and charging time.
The study found that the decision in favor of an electric car was down mainly to reasons of image, whereas personal environmental awareness was of minor importance. On the other hand, it found that the purchase decision was very positively influenced by access to a public charging infrastructure.
Based on driving and charging profiles of potential users, around a quarter of the charging infrastructure is likely to be required in public places, with more than half being needed in semi-public locations such as shopping centers or leisure facilities.
Night-time charging demand is what determines the overall demand for infrastructure, because there is generally only one night-time charge per charging point, whereas several charges are possible during the daytime.
A further focus of the research was to test out Plug&Charge among participants with their own photovoltaic system. Plug&Charge means that charging starts automatically without the need for additional identification. An RWE wallbox allowed intelligent charging to be further developed. eMERGE participants were able to adapt their charging strategy, such as charging their smart fortwo electric drive exactly when sufficient power was available from renewable energy sources. In this case from their own solar system. This enables users to charge in a convenient, intelligent and environmentally aware manner.