hybrid electric vehicles in thermal engineering

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1. Hybrid electric vehicles S oumyashree B iradar Kavya E C Priyanka B N Shruti singh Varsha

2. * A hybrid electric vehicle (HEV) augments an electric vehicle (EV) with a second source of power referred to as the alternative power unit (APU ). * A hybrid can achieve the cruising range and performance advantages of conventional vehicles with the low-noise, low-exhaust emissions, and energy independence benefits of electric vehicles * Accordingly , the hybrid concept, where the alternative power unit is used as a second source of energy, is gaining acceptance and is overcoming some of the problems of pure electric vehicles. 2 I ntroduction

3. * Any vehicle that combines 2 or more sources of power is said to be hybrid. For example, a moped (a motorized pedal bike ), diesel-electric hybrid locomotives * Relies not only on batteries but also on an internal combustion engine which drives a generator to provide electricity and may also drive a wheel. * Alternative power unit to supply the power required by the vehicle, to recharge the batteries, and to power accessories like the air conditioner and heater. 3 what is hybrid electric vehicle

4. Series hybrid Parallel hybrid Hybrid vehicle configurations

5. In a series hybrid system, the combustion engine drives an electric generator instead of directly driving the wheels. The electric motor is the only means of providing power to the wheels. The generator charges a battery. Series hybrids can be assisted by ultracaps (or a flywheel), which can improve the efficiency by minimizing the losses in the battery. Utracaps deliver peak energy during acceleration and take regenerative energy during braking. Therefore, the ulracaps are kept charged at low speed and almost empty at top speed. Deep cycling of the battery is reduced, the stress factor of the battery is lowered. SERIES STRUCTURE

6. Series structure

7. Series structure

8. There is no mechanical link between the combustion engine and the wheels. The engine generator group can be located everywhere. There are no conventional mechanical transmission elements (gearbox, transmission shafts). Separate electric wheel motors can be implemented easily. The combustion engine can operate in a narrow rpm range (its most efficient range), even as the car changes speed. Series hybrids are relatively the most efficient during stop-and-go city driving. Advantages of series structure

9. The ICE, the generator and the electric motor are dimensioned to handle the full power of the vehicle. Therefore, the total weight, cost and size of the powertrain can be excessive. The power from the combustion engine has to run through both the generator and electric motor. During long-distance highway driving, the total efficiency is inferior to a conventional transmission, due to the several energy conversions. Disadvantages of series structure

10. Fuel tank supplies gasoline to the engine. Set of batteries supplies power to the electric motors. Both the engine and electric motor can turn the transmission at the same time, and the transmission turns the wheels. When the APU is off, the parallel hybrid runs like an electric vehicle When the APU is on controller drives the energy between drive train and batteries Under acceleration more power is allocated to drive train than to the batteries and during periods of idle,more power goes to the batteries than the drive trains. PARALLEL STRUCTURE .

11. Parallel structure

12. Parallel structure

13. Flexible in configurations and gives room for optimization of fuel economy and emissions. Reduced engine size. Possible plug-in hybrid for further improved fuel economy and emission reduction. Advantages of parallel structure

14. Complicated control strategy. Complex transmission. Disadvantages of parallel hybrid

15. 1. Electric motor : Converts electric energy to mechanical energy. It is powered by DC sources such as batteries or by AC sources such as generators. 2. Auxiliary power unit(APU) : It is a device that provides energy for functions other than propulsion. APUs use spark and combustion engines as a source of power. However in recent years fuel cell APUs that nearly eliminate all emissions are used. APU in HEVs supplies baseline power required by vehicles, recharges batteries and power accessories such as air conditioners and heaters. COMPONENTS OF HEV

16. 3. Generator : The combustion engine in serial hybrid drives electric generator. The generator both charges battery and powers motor that moves vehicle. In parallel hybrid there’s no separate generator, motor functions as generator when needed. 4. Energy storage systems : Batteries, flywheels or ultra capacitors are used for energy storage in HEVs Flywheels store energy mechanically by turning heavy rotor to store kinetic energy.

17. Lithium ion batteries are used for their efficiency and high power to weight ratio for energy storage. Ultra capacitors store energy in polarized liquid between an electrode and electrolyte, provides additional power during acceleration. 5. Regenerative breaking : Vehicles relay on friction breaks to slow down, dissipating kinetic energy as heat. Regenerating breaks turns this energy into electricity and stores in batteries. This electricity can later be used to run motors and accelerate vehicle.

18. * Using the concept of Hybridization of cars results in better efficiency and also saves a lot of fuel in today’s fuel deficit world. * A hybrid gives a solution to all the problems to some extent. * If proper research and development is done in this field, hybrid vehicle promises a practical, efficient, low pollution vehicle for the coming era. * One can surely conclude that this concept and the similar ones to follow with even better efficiency & conservation rate are very much on the anvil in today’s energy deficit world. 20 CONCLUSIONS

19. Thank you.....