HİBRİD VE ELEKTRİKLİ ARAÇLAR

Transcription

1 HİBRİD VE ELEKTRİKLİ ARAÇLAR Hibrid Elektrikli Araç Uygulamalarına Örnekler Atkinson Çevrimi Yrd. Doç. Dr. Abdullah DEMİR «Her ter ih ir vazgeçiştir»

2 HİBRİD ARAÇLAR Diesel Hybrids HEVs can also be built around diesel vehicles. All topologies explained earlier, such as series, parallel, series parallel, and complex HEVs, are applicable to diesel hybrids. Due to the fact that diesel vehicles can generally achieve higher fuel economy, the fuel efficiency of hybridized diesel vehicles can be even better when compared to their gasoline counterparts. Vehicles such as delivery trucks and buses have unique driving patterns and relatively low fuel economy. When hybridized, these vehicles can provide significant fuel savings. Hybrid trucks and buses can be series, parallel, series parallel, or complex structured and may run on gasoline or diesel. Diesel locomotives are a special type of hybrid. A diesel locomotive uses a diesel engine and generator set to generate electricity. It uses electric motors to drive the train. Even though a diesel locomotive can be referred to as a series hybrid, in some architectures there is no battery for the main drive system to buffer energy between the I/G set and the electric motor. This special configuration is sometimes referred to as simple hybrid. In other architectures, batteries are used and can help reduce the size of the generator, and can also be used for regenerative energy capture. The batteries, in this case, can also be utilized for short-term high current due to torque needs, without resorting to a larger generator. Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

3 HİBRİT ARAÇLAR The Toyota Prius Toyota produced the world s first mass-marketed modern HEV in 1997, the Prius, as shown in Figure 8. The worldwide sales of the Prius exceeded 1 million units in It uses a planetary gear set to realize continuous variable transmission (CVT). Therefore, conventional transmission is not needed in this system. As shown in Figure 9, the engine is connected to the carrier of the planetary gear while the generator is connected to the sun gear. The ring gear is coupled to the final drive, as is the electric motor. The planetary gear set also acts as a power/torque split device. During normal operations, the ring gear speed is determined by the vehicle speed, while the generator speed can be controlled such that the engine speed is in its optimum efficiency range. The 6.5 Ah, 21 kw nickel metal hydride battery pack is charged by the generator during coasting and by the propulsion motor (in generation mode) during regenerative braking. The engine is shut off during low-speed driving. The same technology has been used in the Camry hybrid, the Highlander hybrid, and the Lexus brand hybrids. However, the Highlander and the Lexus brand hybrids add a third motor at the rear wheel. The drive performance, such as for acceleration and braking, can thus be further improved. Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN

4 HİBRİT ARAÇLAR Figure 8: The Toyota Prius (2010 model) Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

5 HİBRİT ARAÇLAR Figure 9: The powertrain layout of the Toyota Prius (EM, Electric Machine; PM, Permanent Magnet) Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

6 Table 1: Partial list of HEVs available in the United States a Comparison to Corolla. b Comparison to Civic. c Saturn Brand vehicle including Vue and Saturn Aura are not offered. d Chrysler Aspen uses similar platform as Durango but is no longer offered. Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

7 HİBRİD ARAÇLAR The Honda Civic The Honda Civic hybrid has an electric motor mounted between the ICE and the CVT, as shown in Figure 10. The electric motor either provides assistance to the engine during high power demand, or splits the engine power during low power demand. Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

8 HİBRİD ARAÇLAR Figure 10: The powertrain layout of the Honda Civic hybrid Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives,

9 HİBRİD ARAÇLAR The Ford Escape The Escape hybrid from the Ford Motor Company (Figure 11) is the first hybrid in the SUV category. The Escape hybrid adopted the same planetary gear concept as the Toyota system. Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

10 HİBRİD ARAÇLAR Figure 11: The Ford Escape hybrid SUV Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

11 The Two-Mode Hybrid The GM two-mode hybrid transmission was initially developed by GM (Alison) in 1996, and later advanced by GM, Chrysler, BMW, and Mercedes-Benz with a joint venture named Global Hybrid Cooperation in The GM two-mode hybrids (Figure 12) use two planetary gear sets and two electric machines to realize two different operating modes, namely, high-speed mode and low-speed mode. HİBRİD ARAÇLAR Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

12 HİBRİD ARAÇLAR Figure: The Chrysler Aspen two-mode hybrid

13 HİBRİD ARAÇLAR Challenges and Key Technology of HEVs HEVs can overcome some of the disadvantages of battery-powered pure EVs and gasoline powered conventional vehicles. These advantages include optimized fuel economy and reduced emissions when compared to conventional vehicles, and increased range, reduced charging time, and reduced battery size (hence reduced cost) when compared to pure EVs. However, HEVs and PHEVs still face many challenges, including higher cost when compared to conventional vehicles; electromagnetic interference caused by high-power components; and safety and reliability concerns due to increased components and complexity, packaging of the system, vehicle control, and power management: Power electronics and electric machines: The subject of power electronics and electric motors is not new. However, the use of power electronics in a vehicle environment poses significant challenges. Environmental conditions, such as extreme high and low temperatures, vibration, shock, and transient behavior are very different from what electric motors and power electronic converters have been used to. Challenges in power electronics in a HEV include packaging, size, cost, and thermal management. Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

14 HİBRİD ARAÇLAR Challenges and Key Technology of HEVs (Cont.) Electromagnetic interference: High-frequency switching and highpower operation of power electronics and electric motors will generate abundant electromagnetic noise that will interfere with the rest of the vehicle system if not dealt with properly. Energy storage systems: Such systems are a major challenge for HEVs and PHEVs. The pulsed power behavior and energy content required for the best performance are typically difficult for conventional batteries to satisfy. Life cycle and abuse tolerance are also critical for vehicle applications. At the present time, nickel metal hydride batteries are used by most HEVs and lithium-ion batteries are targeted by PHEVs. Ultracapacitors have also been considered in some special applications where power demand is a major concern. Flywheels have also been investigated. The limitations of the current energy storage systems are unsatisfactory power density and energy density, limited life cycle, high cost, and potential safety issues. Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

15 HİBRİD ARAÇLAR Challenges and Key Technology of HEVs (Cont.) Regenerative braking control: Recovering the kinetic energy during braking is a key feature of HEVs and PHEVs. However, coordinating regenerative braking with the hydraulic/frictional braking system presents a major challenge as far as safety and braking performance are concerned. Power management and vehicle control: HEVs involve the use of multiple propulsion components that require harmonious coordination. Hence, power management is a critical aspect of vehicle control functions in a HEV. A optimized vehicle controller can help achieve better fuel efficiency in a HEV. Thermal management: Power electronics, electric machines, and batteries all require a much lower operating temperature than a gasoline engine. A separate cooling loop is necessary in a HEV. Modeling and simulation, vehicle dynamics, vehicle design, and optimization: Due to the increased number of components in a HEV, packaging of the components in the same space is a challenge. Associated vehicle dynamics, vehicle design, and modeling and simulation all involve major challenges. Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

16 ÖZETLE: HİBRİD ARAÇLARIN KONFİGÜRA YONU (a) Series (electrically coupling), (b) parallel (mechanical coupling), (c) series parallel (mechanical and electrical coupling, (d) complex (mechanical and electrical coupling).

17 HİBRİD ARAÇLAR Other Approaches to Vehicle Hybridization The main focus of this presentation is on HEVs, that is, electric gasoline or electric diesel hybrids. However, there exist other types of hybridization methods that involve other types of energy storage and propulsion, such as compressed air, flywheels, and hydraulic systems. Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

18 HİBRİD ARAÇLAR Other Approaches to Vehicle Hybridization (Cont.) A typical hydraulic hybrid is shown in Figure 6. Hydraulic systems can provide a large amount of torque, but due to the complexity of the hydraulic system, a hydraulic hybrid is considered only for large trucks and utility vehicles where frequent and extended period of stops of the engine are necessary. Figure 6: A parallel hydraulic hybrid vehicle (LP, Low Pressure) Chris Mi, M. Abul Masrur, David Wenzhong Gao, Hybrid Electric Vehicles - Principles And Applications With Practical Perspectives, ISBN , 2011.

19 ATKINSON CYCLE ENGINE

20 MILLER CYCLE ENGINE Otto motorlardan farkı olarak, Miller çevrimi motorlarda, 4 zamanlı motorlardaki sıkıştırma s recinde ortaya çıkan enerji kaybı daha d ş kt r. Patenti Amerikalı m hendis Ralph Miller tarafında 1940 yılında alınmıştır. İlk örnekleri gemilerde ve g ç retim istasyonlarında kullanılmıştır.

21 MILLER CYCLE ENGINE Mazda s naturally-aspirated MZR 1.3L Miller-cycle engine delays the closure of the intake valves to improve the thermal efficiency (high expansion ratio). Sequential-valve timing (S- VT) is also employed to optimize intake valve timing and ensure sufficient torque for cruising and accelerating. Miller Cycle Sequential Valve Timing (S-VT) Continuously Variable Transmission (CVT)

22 MILLER CYCLE ENGINE Miller Cycle Sequential Valve Timing (S-VT) Continuously Variable Transmission (CVT)

23 ATKINSON CYCLE ENGINE

24 ATKINSON CYCLE ENGINE

25 ATKINSON CYCLE ENGINE Note: High Efficiency Hybrid Cycle (HEHC)

26 ATKINSON CYCLE ENGINE Note: High Efficiency Hybrid Cycle (HEHC)

27 ATKINSON CYCLE ENGINE The Atkinson cycle engine is definitely not a new design having been invented in Because the cycle has advantages when applied to hybrids, the 1882 invention is enjoying a period of popularity. See Figure, which shows the various strokes of a four-stroke engine with intermediate positions as well. Key features of Atkinson cycle are a long expansion stroke which allows extraction of more energy. The short compression stroke reduces pumping losses. The design allows retaining and designing any compression ratio desired. The results are improved engine efficiency which is provided at the expense of power. Hybrid Vehicles and the Future of Personal Transportation

28 ATKINSON CYCLE ENGINE That is the good news; now for the bad news. Due to the reduced charge, discussed presently, the power is reduced compared to the same engine of equal displacement. Charge is the maximum mass of fuel plus air in the cylinder; usually this mass occurs when the piston is at TDC and all valves are (nearly) closed ready for expansion stroke. Some relevant definitions: as crankshaft angle passes through 0, the piston pauses and stops; hence the word dead to describe top dead center (TDC). Closing all valves for improved regenerative braking. Engine operation is analogous to lowloss motion of a spring with a mass, m. The minimum loss for an engine is attained with all valves closed. Lowloss: Az kayıplı Hybrid Vehicles and the Future of Personal Transportation

29 ATKINSON CYCLE ENGINE Hybrid Vehicles and the Future of Personal Transportation An open intake valve is like leaving the door open; the charge leaks out. Compression is delayed creating a shortened compression stroke, which is one feature of the Atkinson cycle (see sketch C). Sketch F shows full expansion stroke, which is another feature of the Atkinson cycle. Figure provides an excellent way to understand reduced pumping losses from the Atkinson cycle as applied to a four-stroke engine. The pressure traces enclose two areas, I and II.

30 ATKINSON CYCLE ENGINE Analysis shows that the area enclosed in I is proportional to the energy produced by the engine. Since the test equipment that yields the pressure volume curves is known as an indicator, the energy of I is termed indicated energy. Area II involves moving the gases in and out of the cylinder; this is called pumping. Hence, the term pumping loss is applied to II. The net output of energy from the engine is Net energy = Indicated energy - Pumping loss Considerable confusion exists in the popular press about pumping loss. Hybrid Vehicles and the Future of Personal Transportation

31 ATKINSON CYCLE ENGINE FIGURE: Pressure shown as function of volume within cylinder as piston moves from TDC to BDC. The four strokes are D E, compression; E A B, expansion; B C, exhaust; and C D, intake. Pressures within a cylinder are measured as engine is operating at part throttle. The magnitude of pumping loss depends on the throttle setting. Consider the ratio of pumping loss divided by net work done by the engine. At full throttle, the pumping loss ratio is 1% 3%. At partial throttle, the pumping loss ratio is much larger being 30% 40%. Hybrid Vehicles and the Future of Personal Transportation

32 ATKINSON CYCLE ENGINE Hybrid Vehicles and the Future of Personal Transportation In Figure, pa is the ambient pressure. Point D, which is below ambient pressure, is a partial vacuum. Also point D is equal to manifold pressure. In the Otto cycle, the intake valve closes at D, and the charge is being compressed. Notice the pressure curve going upward toward point E. However, with the Atkinson cycle the intake valve remains open. As the piston moves toward TDC from BDC, the pressure remains equal to that at point D. When the intake valve closes, the pressure increases and the curve heads off toward E. Area II is reduced in size by the slice, which is gray shaded. Pumping losses are less. Figure also shows the shortened compression stroke and the comparatively long expansion stroke. The long expansion stroke yields a greater extraction of energy from the fuel.

33 ATKINSON CYCLE ENGINE Biggest disadvantage is reduction in power density (power/unit volume) arising from the reduction in air intake Jacob Reagan, Atkinson Cycle Engines

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35 ATKINSON CYCLE ENGINE

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