1、Electrical Circuit Theory,1,Hybrid electric vehicles,An extra credit presentation by Harry PapacharissiouWith supplementation by Andrew Nafalski,Electrical Circuit Theory,2,Hybrid electric vehicles,What is a HEV?Why HEVsAdvantages of using HEVsTypes of HEVsHEV componentsThe future of HEVs,Electrical
2、 Circuit Theory,3,What is a HEV?,Hybrid electric vehicles (HEVs) combine the internal combustion engine of a normal vehicle with the battery and electric motor of an electric vehicle. This results in twice the fuel economy of conventional vehicles.Also offers the extended range and rapid refuelling
3、that consumers expect from a normal vehicle, with all the energy and environmental benefits of an electric vehicle. Can be used in a wide range of applications, from personal transportation to commercial hauling.,Electrical Circuit Theory,4,Hybrid Electric Vehicle,Combination of petrol engine and el
4、ectric motorEnergy densityPetrol - 12,500 Wh/kgLead Acid battery - 25 Wh/kgNickel-metal hydride battery 44 Wh/kgSeries hybrids: petrol engine drives alternator to store energy in batteries or sent to electric motor which powers the wheels. Petrol engine never supplies the wheels directly.,Electrical
5、 Circuit Theory,5,Why HEVs?,Hybrid power systems were designed as a way to compensate for the shortfall in battery technology. Because batteries could supply only enough energy for short trips, an onboard generator, powered by an internal combustion engine, could be installed and used for longer tri
6、ps. This is the concept of the HEV.Electric vehicles are only being used in selected market applications where fewer kilometres are travelled. Conventional motor vehicles powered by internal-combustion engines (ICE) pose substantial economic, environmental and energy security issues for the planet.,
7、Electrical Circuit Theory,6,Why HEVs?,More efficient cars can make a big difference to society in terms of environmental benefits, and the state of the urban air has motivated buyers to purchase cleaner cars. Use of production HEVs will reduce smog-forming pollutants over the current national averag
8、e.,Electrical Circuit Theory,7,Why HEVs?,Hybrids will never be true zero-emission vehicles, however, because of their internal combustion engine. But the first hybrids on the market will cut emissions of global-warming pollutants by a third to a half, and later models may cut emissions by even more.
9、,The Honda Insight,Electrical Circuit Theory,8,HEV Advantages,One of the most important differences between a HEV and a normal vehicle is the HEVs ability to reclaim a portion of the energy lost to braking. In a HEV, when the driver brakes, the motor becomes a generator, using the kinetic energy of
10、the vehicle to generate electricity that can be stored in the battery for later use. Traditional brakes are necessary, as well as a consistent strategy for smoothly blending the two braking systems. Regenerative and friction brakes need to be controlled electronically so that stopping ability is max
11、imized to make the dual brake operation not noticeable to the driver.,Electrical Circuit Theory,9,HEV Advantages,Regenerative braking (explained above) capability helps minimize energy loss and recover the energy used to slow down or stop a vehicle. Engines can be sized to accommodate average load,
12、not peak load, which reduces the engines weight. Fuel efficiency is greatly increased (hybrids consume significantly less fuel than vehicles powered by gasoline alone). Emissions are greatly decreased. HEVs can reduce dependency on fossil fuels because they can run on alternative fuels. Special ligh
13、tweight materials are used to reduce the overall vehicle weight of HEVs.,Electrical Circuit Theory,10,Types of HEVs,Many configurations are possible for HEVs.Essentially, a hybrid combines an energy storage system, a power unit, and a vehicle propulsion system. The primary options for energy storage
14、 include batteries, ultra capacitors, and flywheels. Although batteries are by far the most common energy storage choice, research is still being done in other energy storage areas. Hybrid power unit options are spark ignition engines, compression ignition direct injection engines, gas turbines, and
15、 fuel cells.,Electrical Circuit Theory,11,Practical realisations,Parallel hybrid: two power paths either engine or motor, or both power the wheels directly.Series hybrid is more efficient but parallel hybrid has higher power output needed in practical conditionsHonda Insight vs Toyota PriusInsight i
16、s pure parallel; Prius uses combination of both (engine power split along two paths wheels and alternator which drives the electric motor and also charges the batteries),Electrical Circuit Theory,12,Types of HEVs,Propulsion can come entirely from an electric motor, such as in a in line (series) conf
17、iguration, or the engine might provide direct mechanical input to the vehicle propulsion system in a V(parallel) system. There are several transmission options when it comes to HEVs as wellthe driver determines which transmission will be most efficient. A hybrids efficiency and emissions depend on t
18、he particular combination of subsystems, how these subsystems are integrated into a complete system, and the control strategy that integrates the subsystems. A hydrogen fuel cell hybrid, for example, would produce only water as a by-product and run at greater overall efficiency than a battery-electr
19、ic vehicle that uses wall-plug electricity.,Electrical Circuit Theory,13,HEV Components,Electrical Circuit Theory,14,HEV Components,A HEV is an optimised mix of many components. The vehicle drive train consists of: Electric traction motors/controllers Electric energy storage systems, such as batteri
20、es, ultra capacitors, and flywheels Hybrid power units such as spark ignition engines, compression ignition direct injection (diesel) engines, gas turbines, and fuel cells Fuel systems for hybrid power units Transmissions,Electrical Circuit Theory,15,HEV Components,There are other key developments b
21、eing made to helpreduce emissions and improve the efficiency of HEVs: Emission control systems Energy management and systems control Thermal management of components Light-weight and aerodynamic body/chassis Low rolling resistance (including tires) Reduction of accessory loads in the vehicle,Electri
22、cal Circuit Theory,16,The future of HEVs,HEVs are now at the forefront of transportation technology development. They are reducing critical resource consumption, dependence on foreign oil, air pollution, and traffic congestion. Their widespread penetration into the automotive market depends mainly o
23、n the economics of producing a complex hybrid power system, rather than the inherent capabilities of the technology itself.,The Toyota Prius,Electrical Circuit Theory,17,The future of HEVs,As with any new technology, there may be obstructions to its acceptance by consumers, But time will soon tell.
24、The Honda Insight is available to United States consumers now, and so far its been getting a lot of attention. The Toyota Prius has been available for sale in Japan since December 1997 and has been a hot seller. To help with market acceptance, federal and state incentives are in place to off-set som
25、e of the HEV purchase costs when they come to Australia for retail sale.,Electrical Circuit Theory,18,Comparison,Electrical Circuit Theory,19,Insight,Substantial fuel saving costsUltra low emissions and fuel economyHEV technology (65%)Weight reduction; Aerodynamics; Reduction in rolling resistance (35%)Source: IEE Review, January 2001,Electrical Circuit Theory,20,THE END,References:,http:/ - Electric vehicle progresshttp:/ - Ford HEV,
