A hybrid electric vehicle combines an electric motor with an internal combustion engine to improve fuel efficiency. There are two main types of hybrid configurations - parallel and series. In a parallel hybrid, both the engine and electric motor can power the wheels directly. In a series hybrid, the engine charges the battery which powers the electric motor to turn the wheels. Fuel cell hybrid vehicles use hydrogen to power an electric motor, providing emissions-free propulsion. Driving at a constant speed, avoiding abrupt stops, and driving more slowly can improve the fuel efficiency of any hybrid vehicle.

1. HYBRID ELECTRIC VEHICLE

2. introductionA hybrid electric vehicle (HEV) augments an electric vehicle (EV) with a second source of power referred to as the alternative power unit (APU).

3. 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

4. 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

5. what is hybrid electric vehicleAny 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

6. 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.

7. 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

8. Hybrid structureTwo types of hybrid vehicle configurations

9. Parallel Hybrids

10. Series Hybrids 4

11. parallel hybridFuel tank, which supplies gasoline to the engine.

12. Set of batteries that supplies power to an electric motor.

13. Both the engine and the electric motor can turn the transmission at the same time, and the transmission then turns the wheels. 5

14. Parallel(contd.)When the APU is off, the parallel hybrid runs like an electric vehicle

15. When the APU is on, the controller divides energy between the drive train (propulsion) and the batteries (energy storage).

16. Under acceleration, more power is allocated to the drive train than to the batteries. During periods of idle or low speeds, more power goes to the batteries than the drive train.

17. The batteries also provide additional power to the drive train when the APU is not producing enough and also to power auxiliary systems such as the air conditioner and heater. 6

18. Series hybridSimilar to an electric vehicle with an on-board generator

19. The vehicle runs on battery power like a pure electric vehicle until the batteries reach a predetermined discharged level.

20. At that point the APU turns on and begins recharging the battery.

21. The APU operates until the batteries are charged to a predetermined level.

22. APU never directly powers the vehicle7

23. Series (contd.)The length of time the APU is on depends on the size of the batteries and the APU itself.

24. Since the APU is not directly connected to the drive train, it can be run at its optimal operating condition; hence, fuel economy is increased and emissions are reduced relative to a pure IC engine vehicle. 8