NOVEL TECHNIQUE FOR HYBRID ELECTRIC VEHICLE

PREPARED BY: MANISH SADHUJAYDEEP SINDHAKARAN CHAUHANANKUR PATEL

GUIDED BY:Prof. Heena Nakum

INTRODUCTION

• This project represents an alternative energy storage system in the drive line of a hybrid electric vehicle.

• The effect of the use of an Supercapacitors as a power buffer to smooth rapid power fluctuations in and out of the batteries of a hybrid electric heavy vehicle is investigated.

• In this work a topology is presented where the performances of a battery pack in parallel with supercapacitors are evaluated in terms of stress and extending battery lifespan.

• According to this association the battery current drawn is reduced and the supercapacitor source supplies the majority of transient current and as a result the battery stress is reduced up to 30 %.

FIG 1:A parallel connection of batteries to Supercapacitors

• Supercapactors have particular advantages for use in fuel cell powered vehicles in which it is likely they can be used without interface electronics.

• Vehicle simulations using those devices have shown that increased power capability in such devices is needed before full advantage can be taken of their increased energy density compared to carbon/carbon devices in some vehicle applications.

• Energy storage system considerations indicate that combinations of supercapactors and advanced batteries (Wh/kg>200) are likely to prove advantageous in the future as such batteries are developed. This is likely to be the case in plug-in hybrids with high power electric motors for which it may be difficult to limit the size and weight of the energy storage unit even using advanced batteries.

INTRODUCTION OF HYBRID ELECTRIC VEHICLE

• The electric vehicles are purely electric-their only energy source is from outlet. These vehicles are at a strong disadvantage today. In world that’s use d to refueling in a matter of minutes, a half–hour recharge time is insufficient. Enter HEVs

• HEV stands for Hybrid Electric Vehicle. A hybrid uses a small internal combustion engine to provide energy to the vehicle in addition to the stored charge in the battery.

• There are different “flavors” of hybrid , which use the stored energy differently.

Advantages of Electric Vehicle

• The number one advantage of an electric vehicle is that no gas is required. One example is the Chevy Volt.

• It has a battery range of 40 miles. That means it can drive for 40 miles without using gas. 40 miles is more than the range of an average commute to work, so you can go to and from work using no gas. With minimal gas usage comes great savings.

• You do need gas in the Volt in case your battery runs out or you go for a long distance. However, the amount of fill ups per year will be much fewer with an electric vehicle

• You can plug the car into any outlet of the proper voltage and charge the car. Electricity is much cheaper than gas, and the savings will be dramatic

• Electric cars give off no emissions. Electric cars are even better than hybrids in this regard. Hybrids running on gas give off emissions, while electric cars are totally 100 percent free of pollutants

• Safety is a big concern with these vehicles. However, the fluid batteries actually take impact better than a fully made gas car, and can help even more in the event of an accident

Disadvantages of Battery

• Requires protection circuit to maintain voltage and current within safe limits.

• Subject to aging, even if not in use - storage in a cool place at 40% charge reduces the aging effect.

• Transportation restrictions - shipment of larger quantities may be subject to regulatory control. This restriction does not apply to personal carry-on batteries.

• Expensive to manufacture - about 40 percent higher in cost than nickel-cadmium.

• Not fully mature - metals and chemicals are changing on a continuing basis

WHY SUPERCAPACITOR ?

• In comparison with rechargeable batteries they endure higher number of cycles, can be charged and discharged a hundred times faster and reach at least 20 years of useful life.

• Supercapacitors were almost always bought for better performance such as starting a truck at minus 40°C. They are very rarely bought because their upfront price is attractive compared to alternatives but they increasingly give lower cost-over-life of a system, less maintenance and more reliability.

• Through the coming decade, upfront costs and energy density will be ever more competitive, opening up many new applications

Rechargeable Batteries Vs. Supercapacitors

Supercapacitors : Higher power density Much faster charge and

discharge rate Environmentally friendly Extremely low internal

resistance or ESR High efficiency (97-98%) Over a million charge-

discharge cycles

Batteries: Have higher energy density Typically 200–1000 charge-

discharge cycles Contain highly reactive and

hazardous chemicals Negatively effected by low

temperatures

Inverter

Super Capacitor

Basic Circuit Diagram

Basic Operations : -

Fig 2: Low Constant Speed Operation Energy Flow

Fig 3: Acceleration Operation Energy Flow ( Need above 24 V)

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Fig 4: Acceleration Operation Energy Flow and Super capacitor charging (Below 13V of SC)

Fig 5: No Operation when super capacitor 12-13 Volt

Fig 6: Re generation when super capacitor below 24 Volt and Battery above 24 Volt

Fig 7: Re generation when super capacitor and Battery both below 24 Volt

The different configurations of EV power supply show that atleast one DC/DC converter is necessary to interface the FC, the Battery or the Super capacitors module to the DC-link.

NON-ISOLATED CONVERTERS• The non-isolated converters type is generally used where the

voltage needs to be stepped up or down by a relatively small ratio (less than 4:1. There are five main types of converter in this non-isolated group, usually called the buck, boost, buck-boost, Cuk and charge-pump converters.

ISOLATED CONVERTERS• Usually, in this type of converters a high frequency transformer is

used. In the applications where the output needs to be completely isolated from the input, an isolated converter is necessary. 19

TYPES OF CONVERTER

• In case of interfacing the Fuel Cell, the DC/DC converter is used to boost the Fuel Cell voltage and to regulate the DC-link voltage.

• Some design considerations are essential for automotive applications:

1. Light weight,2. High efficiency,3. Small volume,4. Low electromagnetic interference,5. Low current ripple drawn from the Fuel Cell or the

battery,6. The step up function of the converter,Control of the

DC/DC converter power flow subject to the wide voltage variation on the converter input.

Electric Vehicle Requirement

Advantages of Supercapacitor

Unlimited cycle life; as compared to the electrochemical battery, they are not subject to the wear or aging.

On-hand charge methods; no full-charge circuit required. Quick charging times. Low impedance; by paralleling it with a battery, it

enhances the pulse current. Cost effective storage; a very high cycle count

compensates the lower density.

Limitations of Supercapacitor

• Low specific energy; holds a fraction of a regular battery

• Linear discharge voltage prevents using the full energy spectrum

• High self-discharge; higher than most batteries• Low cell voltage; requires serial connections

with voltage balancing• High cost per watt

Application

• Maintenance free applications • Public transportation, HEVs, Start-

Stop System • Back-up and UPS systems • Systems of Energy Recuperation• Consumer electronics

Hybrid Supercapacitor Bus in Shanghai – Image from MIT Technology Review

Components Needed

• Battery – 24 V DC (Lead Acid Battery)• Supercapacitor, 1F (4 Pcs)• Bidirectional Dc-Dc Converter Components-• Inductor design, Switching Circuits etc• DC Motor

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