I - ELOOP Braking System - Engineering Seminar

INTRODUCTION

                                                           Brakes are employed to stop or retard the motion of any moving body. Thus, in automobiles the brakes are having the most important function to perform. Its principle object is to absorb energy during deceleration. In vehicles, brakes are used to absorb kinetic energy whereas in hoists or elevators brakes are also used to absorb potential energy. By connecting the moving member to stationary frame, normally brake converts kinetic energy to heat energy. This causes wastage of energy and also wearing of friction lining material. Regenerative braking system is a braking technology which slows down a vehicle without wasting energy. This system converts a vehicle’s kinetic energy into electricity as the driver applies the brakes. 

                                                           This generated electricity can be used to power the electric components of the vehicle.  This reduces the need for the engine to burn extra fuel to generate electricity, thereby improving fuel economy and minimizing the wearing of friction lining material. But the main drawback of this system was the deterioration of batteries due to frequent charging and discharging. But Mazda’s i-ELOOP system is a unique system that rectifies this problem by using an electric double layer capacitor instead of batteries to store energy, which is an advanced and more efficient technology.

BASIC IDEA OF i-ELOOP TECHNOLOGY

  Concept of this regenerative brake is also better understood from bicycle fitted with dynamo. If our bicycle has a dynamo (a small electricity generator) on it for powering the lights, we'll know it's harder to peddle when the dynamo is engaged than when it's switched off. That's because some of our peddling energy is being "stolen" by the dynamo and turned into electrical energy in the lights. If we're going along at speed and we suddenly stop peddling and turn on the dynamo, it'll bring us to a stop more quickly than we would normally, for the same reason: it's stealing our kinetic energy.

                                             Now imagine a bicycle with a dynamo that's 100 times bigger and more powerful. In theory, it could bring our bike to a halt relatively quickly by converting our kinetic energy into electricity, which we could store in a battery and use again later. That's the basic idea behind the i-ELOOP braking technology. This technology is introduced by Mazda. This is an advanced form of the conventional regenerative braking technology.

i-ELOOP BRAKING SYSTEM

Regenerative braking systems are growing in popularity as a fuel saving technology. Batteries aren't the only technology mankind has invented to store electricity. The i-ELOOP braking system or the “intelligent energy loop” braking system is the latest and more advanced form of regenerative braking system which is developed and introduced in the 2011 Tokyo motor show by the famous auto-manufacturers Mazda. This is the world’s first capacitor-based regenerative braking system. This new system is aimed at traditional internal combustion vehicles than the hybrid cars and fully electrified vehicles. Mazda's regenerative braking system is unique because it uses a capacitor, which is an electrical component that temporarily stores large volumes of electricity. Compared to batteries, capacitors can b            e charged and discharged rapidly.

                                               This system uses a specially designed capacitor known as Electric Double Layer Capacitor or EDLC which can be fully charged in seconds. As compared to the traditional battery-based regenerative braking systems, the main advantage of this system is that deterioration of battery is prevented. Also In real-world driving conditions with frequent acceleration and braking, 'i-ELOOP' improves fuel economy by approximately 10 percent.

MAIN PARTS

The main parts of the i-ELOOP technology are:-

·       A variable voltage alternator (12V-25V) for efficient electricity generation as the vehicle decelerates.

·       A high-capacity Electric Double Layer Capacitor that rapidly stores large amounts of electricity and efficiently redistributes it.

·       A DC/DC converter to steps down the electricity from 25V to 12V.

WORKING

 The working of the i-ELOOP system is similar to that of a conventional type regenerative braking system except that it uses a capacitor instead of a battery to store the recovered energy. The i-ELOOP features a new 12-25V variable voltage alternator, a low-resistance electric double layer capacitor (EDLC) and a DC/DC convertor.

                                                The i-ELOOP system starts to recover the kinetic energy the moment the driver lifts off the accelerator pedal and the vehicle begins to decelerate. At that instance the variable voltage alternator starts and generates electricity at up to 25V for maximum efficiency before sending it to the Electric Double Layer Capacitor (EDLC) for storage. The capacitor, which has been specially developed for use in a vehicle, can be fully charged in seconds. The DC/DC convertor steps down the electricity from 25V to 12V before it is distributed directly to the vehicle’s electrical components.

                                                This system also charges the battery as necessary. Providing there is sufficient charge stored, all the vehicle’s electric components are powered by the capacitor and the battery, thereby removing the need for the engine to generate electricity through the alternator by burning extra fuel and thus the fuel economy and the power of the engine is advanced. 

The alternator is switched off when the accelerator pedal is depressed and switched on only when the vehicle is decelerating. During city driving with frequent acceleration and deceleration, charging mostly recommences before the capacitor is fully discharged. Therefore , i-ELOOP can provide nearly the vehicle’s entire electricity requirement. This combination of minimizing the amount of fuel needed for electricity generation and efficiently recovering, storing and reusing energy enables to deliver significantly improved fuel economy.
                                                 ADVANTAGES

Ø  ENERGY CONSERVATION

                                          In conventional friction braking system, during braking the kinetic energy is directly converted to heat energy. Once heat is generated, it is very difficult to reuse. Hence energy is lost during braking in conventional friction braking system. But in i-ELOOP system this kinetic energy is converted into electrical energy which can be used to power the electrical components of the vehicle. Therefore energy is not wasted in i-ELOOP system.

Ø  WEAR REDUCTION

                                         In i-ELOOP technology when the driver lifts off the accelerator pedal and the vehicle starts decelerating, the alternator starts and resists the turning of the wheels, capturing some of the energy of motion as if it were a generator and returning that energy to the Electric Double Layer Capacitor (EDLC) for storage. This reduces the use of brakes and extends the life of the friction materials. But in conventional friction braking system lessening wear and extending brake life is not possible.

Ø  FUEL ECONOMY

                                         In low-speed, stop-and-go traffic where little deceleration is required; the i-ELOOP system can provide the majority of the total braking force. This vastly improves fuel economy of a vehicle. At higher speeds too, i-ELOOP braking system improves the fuel economy – by as much as 20%.

Ø  BRAKING IS NOT TOTAL LOSS

                                         Conventional brakes apply friction to convert a vehicle’s kinetic energy into heat. In energy terms, therefore, braking is a total loss. Once heat is generated, it is very difficult to reuse. The i-ELOOP system slows down a vehicle in a different way.

      DISADVANTAGES

·      Compared to the conventional friction braking systems, the i-ELOOP technology is more expensive because of the presence of extra components.

·              Most road vehicles with regenerative braking only have power on some wheels (as in a two-wheel drive car) and regenerative braking power only applies to such wheels, so in order to provide controlled braking under difficult conditions (such as in wet roads) friction based braking is necessary on the other wheels.

·            The regenerative braking effect drops off at lower speeds; therefore the friction brake is still required in order to bring the vehicle to a complete halt. Physical locking of the rotor is also required to prevent vehicles from rolling down hills.

·               The amount of electrical energy capable of dissipation is limited by either the capacity of the supply system to absorb this energy or on the state of charge of the battery or capacitors. Regenerative braking can only occur if no other electrical component on the same supply system is drawing power and only if the battery or capacitors are not fully charged. For this reason, it is normal to also incorporate dynamic braking to absorb the excess energy.

FUTURE PROSPECTS

                                Regenerative braking systems are growing in popularity as a fuel saving technology now days. ‘i-ELOOP’ braking system is the world’s first capacitor based regenerative braking system. This system is mainly aimed at traditional internal combustion engines rather than the fully electric vehicles and the hybrid vehicles. Mazda- the manufacturers of the i-ELOOP system claims that this system will be appearing in their cars by the end of 2012. ‘i-ELOOP’ also works in conjunction with Mazda’s unique ‘i-stop’ idling stop technology to extend the period that the engine can be shut off. By combining these technologies with other electric devices that enhances fuel economy by eliminating unnecessary fuel consumption, the future automobile field is striving to deliver vehicles with excellent environmental performance as well as good driving performance.