Hybrid Electric Vehicles
One of the most popular symbols of the “green” movement is the hybrid-electric car, also known as the hybrid car. These vehicles are better when it comes to the functionality of traditional internal combustion engines because they are combined with a battery-powered electric motor, which takes some of the work off the combustion engine’s hands.
Basics:
Hybrids – A hybrid electric vehicle (HEV) is a type of hybrid vehicle and electric vehicle which combines a conventional internal combustion engine (ICE) propulsion system with an electric propulsion system. The presence of the electric powertrain is intended to achieve either better fuel economy than a conventional vehicle, or better performance. Hybrids can achieve Co2 savings of between 24% and 41% compared to normal petrol vehicles. [1]
This work is focused at optimizing an ethanol reforming process over a Ni/Cu catalyst to produce a hydrogen rich stream in order to feed a solid polymer fuel cell (SPFC). The effect of the reaction temperature, H2O/EtOH and O2/EtOH molar ratios of the feed to the reformer was studied under diluted conditions in order to maximize the hydrogen content and the CO2/COx molar ratio at the outlet of the ethanol reformer. Based on the experimental results, a detailed kinetic scheme of the ethanol reforming was discussed as a function of the temperature, special attention was paid to the role of oxygen in the reaction selectivity and coke formation. Moreover, the coke nature was evaluated by transmission electron microscopy (TEM) and TPO and TPH experiments. The tests carried out at on-board reformer conditions allowed a hydrogen rich mixture (33%) in the outlet reformer flow that can be even increased by water gas sift reactions downstream. The high hydrogen content of the flow to the fuel cell together with the stability of the Ni/Cu catalyst, fully demonstrated by long time runs, can be considered of high interest for SPFC applications. [2]
A very efficient energy-management system for hybrid electric vehicles (HEVs), using neural networks (NNs), was developed and tested. The system minimizes the energy requirement of the vehicle and can work with different primary power sources like fuel cells, microturbines, zinc-air batteries, or other power supplies with a poor ability to recover energy from a regenerative braking, or with a scarce power capacity for a fast acceleration. The experimental HEV uses lead-acid batteries, an ultracapacitor (UCAP) bank, and a brushless dc motor with nominal power of 32 kW, and a peak power of 53 kW. The digital signal processor (DSP) control system measures and stores the following parameters: primary-source voltage, car speed, instantaneous currents in both terminals (primary source and UCAP), and actual voltage of the UCAP. When UCAPs were installed on the vehicle, the increase in range was around 5.3% in city tests. However, when optimal control with NN was used, this figure increased to 8.9%. The car used for this experiment is a Chevrolet light utility vehicle (LUV) truck, similar in shape and size to Chevrolet S-10, which was converted to an electric vehicle (EV) at the Universidad Catolica de Chile. Numerous experimental tests under different conditions are compared and discussed. [3]
This paper describes the mathematical modeling, analysis, and simulation of a dynamic automatic manual layshaft transmission and dry clutch combination powertrain model, and corresponding coordinated control laws synthesized using a conventional SI ICE powerplant-alternator combination, a dry clutch and manual transmission/differential, variable field alternator, brakes, and complete vehicle longitudinal dynamics with tire-road interface characterization. The conventional power train model is validated using experimental test data confirming accurate emulation of dynamic components of the pre-hybridized vehicle. In addition, the development of dynamic series and parallel hybrid electric vehicle (HEV) powertrain models and corresponding coordinated control laws are described. A discussion of the key issues associated with coordinated control law development is provided. Simulations of the dynamic behavior of two types of series HEVs are shown. [4]
An electric car is powered by an electric motor instead of a gasoline engine. The electric motor gets energy from a controller, which regulates the amount of power—based on the driver’s use of an accelerator pedal. The electric car (also known as electric vehicle or EV) uses energy stored in its rechargeable batteries, which are recharged by common household electricity. [5]
Conclusion:
Electric cars are very efficient in not producing tailpipe emissions, reducing our dependency on oil, and in being cheaper to operate. The biggest automakers are expected to start introducing a new generation of electric cars since battery technology improves. It simultaneously increases energy storage and reducing cost. The new trend of being green is to develop further.
References:
[1] http://www.greenpathtransfers.com/goinggreen
[2] ”Ethanol reforming for hydrogen production in a hybridelectricvehicle: process optimisation” by: V Klouza, V Fierroa, P Dentona, H Katzb, J.P Lisseb, S Bouvot-Mauduitc, C Mirodatosa
[3] ”Energy-management system for a hybrid electric vehicle, using ultracapacitors and neural networks” by: Moreno, J. et al
[4] ”Dynamic modeling and control of hybrid electric vehicle powertrain systems” by: Powell, B.K. et al
[5] http://www.hybridcars.com/electric-car
