Small tactical UAVs (SUAVs) have made their mark in military operations with their ability to gather and provide localized, real-time information. Typical uses include perimeter surveillance of remote military compounds, over-the-horizon surveillance, and remote monitoring of critical logistics routes. However, their potential to take on increased and increasingly complex missions is hampered by their limited endurance. This work explores research done under the auspices of the European Commission’s Fuel Cell and Hydrogen Joint Undertaking on a fuel cell and battery hybrid energy storage system that could increase the total amount of onboard energy storage, while continuing to deliver the peak power needs of the SUAV.
Advanced Management System for Lithium-ion Batteries in Hybrid Inverters Optimized for Photovoltaic Systems Connected to the Grid
Abstract One main feature of the power demand profile is it varies time to time and its price changes accordingly. During the peak the less cost-effective and flexible power supplies must complement the base-load power plants in order to supply the power demand. Conversely, during the off-peak period when less electricity is consumed, those costly power plants can be stopped. This is a scenario which Energy Storage System (ESS) and photovoltaic (PV) generation plants could add flexibility and cost reduction to the customers and utilities. These aspects are only achieved due to the ESS, which enables the optimal use of energy produced by the photovoltaic modules through load management and discharge of the battery in the most convenient times.
Abstract In order to improve efficiency and increase the operation of electric vehicles, assistive energy regeneration systems can be used. A hydraulic energy recovery system is modeled to be used as a regenerative system for supplementing energy storage for a pure electric articulated passenger bus. In this study a pump/motor machine is modeled to transform kinetic energy into hydraulic energy during braking, to move the hydraulic fluid from the low pressure reservoir to the hydraulic accumulator. The simulation of the proposed system was used to estimate battery savings. It was found that on average, approximately 39% of the battery charge can be saved when using a real bus driving cycle.
Abstract Energy storage options for a hybrid electric commercial single aisle aircraft were investigated. The propulsion system features twin Geared Turbofan™ engines in which each low speed spool is assisted by a 2,500 HP electric motor during takeoff and climb. During cruise, the aircraft is powered solely by the turbine engines which are sized for efficient operation during this mission phase. A survey of state of the art energy storage options was conducted. Battery, super-capacitor, and flywheel metrics were collected from the literature including Specific Energy (Wh/kg), Volumetric Energy Density (Wh/L), Specific Power (W/kg), Cost ($/kWh), and Number of Cycles. Energy storage in fuels was also considered along with various converters sized to produce a targeted quantity of electric power. The fuel and converters include fuel cells (both proton exchange membrane and solid oxide operating on hydrogen or on jet fuel) and a turbogenerator (jet fuel or LNG).
This paper describes challenges and possible solution of hybrid electrical vehicles test systems with a special focus on hardware-in-the-loop (HIL) test bench. The degree of novelty of this work can be seen in the fact that development and test of ECU for hybrid electrical powertrains can move more and more from mechanical test benches with real automotive components to HIL test systems. The challenging task in terms of electrical interface between an electric motor ECU and an HIL system and necessary real-time capable simulation models for electric machines have been investigated and partly solved. Even cell balancing strategies performed by battery management systems (BMU) can be developed and tested using HIL technology with battery simulation models and a precise cell voltage simulation on electrical level.
The Effect of Driving Conditions and Ambient Temperature on Light Duty Gasoline-electric Hybrid Vehicles (3): Battery Energy
The dependence of gasoline-electric hybrid vehicle energies on driving conditions and ambient temperature is presented for different drive cycles (2xLA4, 2xLA92, 2xUS06, HWFET and 2xNYCC) and temperatures (20°C and -18°C). The tests were carried out at the Emissions Research and Measurement Division of Environment Canada. Hybrid battery pack current was measured at a frequency of 10 Hz. Regenerative braking energy, charging energy from the engine and battery discharge energy were estimated by using modal speed. The magnitudes of battery energies were found to be directly related to drive cycle properties. Battery discharge energy was very strongly correlated to emission factors of CO₂, while energy recovered by regenerative braking and charging energy from the engine had low to very strong correlations to CO₂ emission factors. CO, NOx and HC had low linear correlations to battery discharge energy.
The Effect of Driving Conditions and Ambient Temperature on Light Duty Gasoline-Electric Hybrid Vehicles (2): Fuel Consumption and Gaseous Pollutant Emission Rates
Fuel consumption and gaseous emission data (CO, NOx, THC, and CO2) are reported for four commercially available gasoline-electric hybrid vehicles and one conventional gasoline vehicle tested on a chassis dynamometer over five transient driving cycles (LA4, LA92, HWFET, NYCC, US06), and two steady state modes (40 and 80 km/h), at two ambient temperatures (20 °C, and -18 °C). All vehicles exhibited higher fuel consumption during transient cycles compared to steady-state modes. Cold ambient temperature had a more detrimental effect on fuel consumption rates of the hybrid vehicles compared to those of the conventional gasoline vehicle.
The Effect of Driving Conditions and Ambient Temperature on Light Duty Gasoline-Electric Hybrid Vehicles (1): Particulate Matter Emission Rates and Size Distributions
Gasoline-electric hybrid vehicle technology has been gaining widespread acceptance and has the potential to reduce emissions through reduced fuel consumption. In this study, particulate matter number and mass emission rates, organic and elemental carbon compositions, and number-based size distributions were measured from four gasoline-electric hybrid vehicles (2005 Ford Escape Hybrid, 2004 Toyota Prius, 2003 Honda Civic Hybrid, and 2000 Honda Insight). In addition, one small conventional gasoline vehicle (2002 SmartCar) was tested. The vehicles were driven over five driving cycles and at steady-state speeds of 40 and 80 km/h. Each test was performed at 20°C and at -18°C. Testing took place at the Environmental Science & Technology Centre of Environment Canada using conventional chassis dynamometer procedures. Average distance based emission rates are given for each vehicle under each test condition.
During a special scientific project (SFB 365), supported by the DFG, a parallel hybrid concept for passenger cars, called the Autark Hybrid, was developed, assembled and investigated. The drive line consists an electric engine supplied by a 120V-Ni/MH-battery for about 30 km electrical driving distance and a turbo diesel engine. Both engines use the same gearbox, the i2-gearbox, which is specially designed to have a wide spreading. Significant fuel savings are achieved by recuperation of kinetic energy and by avoidance of inefficient operation of the ic-engine at areas of low power demand. The results from the research project concerning fuel consumption, respectively fuel saving will be presented and discussed in this paper. The adjustment between simulation and test rig investigations shows problems by the practical realisation of operation strategy and operation mode of the powertrain elements. As result smaller fuel savings can be realised than predicted.
Turbogenerator based Hybrid Versus Dieselelectric Hybrid - A parametric optimisation simulation study
Hybrid electric vehicle powertrains are inherently complex due to the numerous possibilities which such systems allow. Not only can the choice of components be varied, but the relative sizes and control strategy of the components will have a significant impact on the performance of the powertrain. The application of the vehicle will also have an enormous effect, since this will govern the mass of the vehicle and the performance which is required. In order to optimise the vehicle, the most important performance parameters must be clearly understood, be they highest efficiency, greatest range, lowest emissions, greatest acceleration performance or lowest cost. Given the number of variables, it is sensible to assess different options by means of simulation of the various powertrains. It is also prudent to include computational mechanisms for automatic sizing of the components for different design cases such that the solution time is minimised.
Using an electric hybrid leads to a significant improvement in vehicle fuel economy. Unfortunately, it also leads to a substantial increase in cost. Regenerative compression braking offers another way to achieving the same objective without incurring the same cost penalty. With some modifications, the vehicle engine can perform both absorption and recovery of braking energy, using compressed air for energy storage. The process parallels the one employed by electric hybrids, but it requires none of the expensive electric equipment used in hybrid systems. This paper reviews basic principles of regenerative compression braking and its advantages in comparison to electric hybrid systems. It also describes the required changes in engine system and methods of control. Description and mathematical analysis of applicable thermodynamic cycles is given, including computations of cycle efficiencies and indicated mean effective pressures produced during braking and acceleration.
This paper analyzes the hybridization of a conventionally powered light duty front wheel drive pick up truck by adding an electric motor driven rear axle. Also studied are the effects of using propane fuel instead of gasoline. This hybrid powertrain configuration can be described as a parallel hybrid electric vehicle. Supervisory power management control has been developed to best determine the proportion of load to be provided by the engine and/or electric motor. To perform these analyses, a simulation tool (computer model of the powertrain components) was developed using MATLAB/SIMULINK'. The models account for the thermal and mechanical efficiencies of the components and are designed to develop control strategies for meeting road loads with improved fuel economy and reduced emissions. Results of this study have shown that fuel economy can be improved and emissions reduced using commercially available components (motor, rear axle, and lead acid batteries).
The Development of a Chrysler Neon Natural Gas/Electric Hybrid Vehicle at Western Washington University
A 1995 Chrysler Neon has been converted to operate as a Natural Gas/Electric parallel hybrid vehicle to compete in the 1995 Hybrid Electric Vehicle Challenge. A hybrid strategy and vehicle control system have been developed to provide zero emissions within the city, and an automatic transition in hybrid mode between electric and CNG power. Emissions, driveability, consumer acceptability, and heating and air conditioning performance in hybrid mode were major considerations in this conversion. Modifications, components, and system functions are described in detail. Additional insights are included regarding performance, successes, and areas of further work. This vehicle placed third overall at the competition, achieved first place in three events, and received the award for best application of advanced technology.
A hybrid bus powered by a diesel engine and a battery pack has been analyzed over an idealized bus-driving cycle in Chicago. Three hybrid configurations, two parallel and one series, have been evaluated. The results indicate that the fuel economy of a hybrid bus, taking into account the regenerative braking, is comparable with that of a conventional diesel bus. Life-cycle costs are slightly higher because of the added weight and cost of the battery.
Santa Barbara County does not meet federal and state health-based standards for ozone. As a result, the County is making significant efforts to reduce pollution from motor vehicles. The Innovative Technologies Group of the Santa Barbara County Air Pollution Control District conducts clean fuel and energy demonstration programs as a strategy to reduce motor vehicle pollution. One such program, a hybrid bus powered by a combination of electricity provided by onboard batteries and a compressed natural gas engine, is described in this paper. A feasibility study has been completed and construction of demonstration buses will occur in the near future. The feasibility study indicated that, for the inter-city commuter route under consideration, a parallel hybrid drive system is preferred, and offers low engine exhaust emissions and high fuel economy.
Abstract Various hybrid drive configurations are described and their advantages and disadvantages for application in passenger cars are discussed; specifically, these are the series hybrid, the parallel hybrid, hybrid drives with added torque and speed, single and two-shaft hybrids. The Volkswagen and AUDI group has developed different vehicles with hybrid drive for various applications. These vehicles are described and test results are presented on their energy consumption, emissions and driving performance. In conclusion, some considerations are pursued concerning their chances on the market in different scenarios.
This computor simulation analysis has been tried as an efficiency study using the Daihatsu Engine/Electric Hybrid 1.5 ton truck which has the “DHS” systems, and run in accordance with three driving patterns such as U.S. LA-4, Australian eight and Japanese ten modes. Every input data are measured and/or evaluated through the actual test and, for the selection of the four driving modes the “DHS” has, three cases of specific fuel consumptions of 190,200 and 210 gr/PS gr/PS · h contour lines are used. As results, the accurate differences of the fuel consumption has been found under every cases.
A diesel-electric hybrid bus has been developed at the University of Florida. The drive system is a series hybrid with two lead-acid batteries and a diesel-driven three phase alternator. It was designed with the aid of a computer simulation program, and has undergone three evaluation phases since the initial construction phase. All results to date have confirmed the feasibility of the system including apparent significant advantages in the areas of exhaust emissions and fuel consumption.
Tests performed on three different configurations of hybrid vehicles establish that significant quantities of on-board petroleum fuel can be conserved by allowing the batteries to be discharged during the driving mission. The depleted batteries are then charged when the vehicle is not in use. Savings of as much as 50% of the on-board petroleum have been experienced with tests on the FDC. On SAE J227a, gasoline FE greater than 50 mpg was measured. Part of the energy for driving is thus transferred from on-board petroleum to off-board electricity generated from coal, hydro-electric or nuclear power plants, with no sacrifice in vehicle performance. The total energy used, when considering the replacement of energy to recharge the batteries, is analyzed. The results are favorable for the hybrid. A recommended new driving cycle for testing hybrids is discussed briefly.
Out of environmental hazards caused by motor vehicles in big cities in Japan, the exhaust gas is being subject for the strict regulations by the Government but the noise is still looked over relatively; people living in the urban area charges more strongly that they are inconvenienced by noises created by trucks passing by in the nighttime in particular. In compliance with these social needs, Daihatsu Motor Co., Ltd. which has been atop in developing electric vehicles now presents a new type vehicle called "Engine-Electric Hybrid 1.5 ton Truck" which is powered by either of diesel engine and electricity so that it becomes possible to drive it by using electric motor in populated area while speeding up by using diesel engine in the highway. That is, this new truck succeeded in the combination of both merits of electric vehicles and conventional automobiles, non-pollution of the former and benefits by high performance and economy of the latter.
A “compound” parallel ICE/battery-electric hybrid automobile has yielded emissions (gms/mi) less than 0.41 HC, 3.40 CO, and 1.0 NOx on the FDP when tested by the EPA. Fuel economy increased 50% on the FEC with partial battery depletion. The 4,100 lb. curb weight vehicle has a top speed over 70 mph, with 0-60 mph in 16 seconds. Low fuel consumption was not a goal in this vehicle. The requirement of 10 mpg was set in 1970 for the FCCIP. FE of 30 mpg or more is projected with known techniques for reducing fuel consumption. A small ICE and a dc dynamotor (generator/motor) on the same shaft drive the vehicle through a conventional clutch and gears. HC and CO are reduced by a thermal reactor. EGR reduces NOx. The ICE operates with a quasi-constant manifold vacuum. Analysis show that in commuter applications, fuel economy can be increased 60% with partial battery depletion, by hybridizing any conventional car.
A study was made to determine the effect of hybrid operation on the fuel economy and emissions of a vehicle using a gas turbine engine, a continuously variable transmission, and an electric power storage system. Both series and parallel hybrids were considered in a 1815 kg vehicle. To facilitate this study, a computer program was written which modeled the vehicle and, using experimental data, computed its fuel consumption and emissions over the 1972 FTP driving cycle, starting with a fully warmed up engine. This study indicates that, under certain conditions, the fuel consumption or emissions of the hybrid vehicle may be reduced as compared to its non-hybrid counterpart, but under other conditions, they may be increased. It is not possible to reduce fuel consumption and all of the emissions simultaneously. The reduction of one pollutant is usually accompanied by an increase in one of the others.
This paper describes an experimental vehicle design by the GM Research Laboratories to explore the use of a low-emission engine and electric drive system in a small car. For this study, a 1968 Opel Kadett has been modified to use a variable-speed ac electric motor to drive the rear wheels through reduction gears and the differential. Batteries provide electric power to the motor through electronic circuitry that gives the variable frequency required for speed control. A small Stirling engine, driving an alternator, supplies energy to the batteries.