mazda 'i-eloop'

the world's first capacitor-based regenerative braking system for passenger vehicles


The best way to harvest what is essentially 'free' engine power under braking, or when running on a trailing throttle for example, has challenged engineers for decades. The most common solution is brake energy regeneration: capturing kinetic energy that would otherwise be lost when slowing down.

Such systems have been in use for a number of years. For instance, Formula One racing cars started to use them in 2009, while BMW/MINI's regenerative braking system has also been fitted to BMW and MINI models late 2007. However, Mazda's system is unique. i-ELOOP, short for "intelligent Energy Loop", is the world's first passenger car system to use a capacitor to store the electricity.

In 2011, Mazda Motor Corporation announced that the company had developed the world's first passenger vehicle regenerative braking system that uses a capacitor. The groundbreaking 'i-ELOOP' system began to appear in Mazda's vehicles in February 2013. The all-new Mazda6 was the first of Mazda's SKYACTIV technology models to be available with i-ELOOP, and in real-world driving conditions with frequent acceleration and braking, 'i-ELOOP' improves fuel economy by approximately 10 percent.

Mazda's regenerative braking system is unique because it uses a capacitor, an electrical component that temporarily stores large volumes of electricity. Compared to batteries, capacitors can be charged and discharged rapidly and they are resistant to deterioration through prolonged use. 'i-ELOOP' efficiently converts the vehicle's kinetic energy into electricity as it decelerates. The system uses the electricity to power the climate control, audio system and numerous other electrical components.

As a fuel saving technology regenerative braking systems are growing in popularity. They employ an electric motor or alternator to generate electricity as the vehicle decelerates, thereby recovering a proportion of the vehicle's kinetic energy. Regenerative braking systems in hybrid vehicles generally use a large electric motor and dedicated battery.

Mazda's engineers examined automobile acceleration and decelerating mechanisms, and developed a highly efficient regenerative braking system that recovers a large amount of electricity rapidly every time the vehicle decelerates. Unlike hybrid vehicles, Mazda's system also avoids the need for a dedicated electric motor and battery. 'i-ELOOP' starts to recover kinetic energy the moment the driver lifts off the accelerator pedal and the vehicle begins to decelerate.

'i-ELOOP' features a new 12-25V variable voltage alternator, a low-resistance electric double layer capacitor and a DC/DC converter. The variable voltage alternator generates electricity at up to 25V for maximum efficiency before sending it to the Electric Double Layer Capacitor (EDLC) for storage.

The capacitor, specially developed for use in a vehicle, can be fully charged in seconds. The DC/DC converter steps down the electricity from 25V to 12V before it is distributed directly to the vehicle's electrical components. The system can also charge the vehicle battery as necessary. 'i-ELOOP' operates whenever the vehicle decelerates, reducing the need for the engine to burn extra fuel to generate electricity. As a result, in "stop-and-go" driving conditions, there is an improvement in fuel economy by around10 percent.

The name 'i-ELOOP' is an adaptation of "Intelligent Energy Loop" and represents Mazda's intention to efficiently cycle energy in an intelligent way. '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 down.

The Japanese manufacturer is working to maximize the efficiency of internal combustion engine vehicles with its pioneering SKYACTIV TECHNOLOGY. By combining this with i-stop, i-ELOOP and other electric devices that enhance fuel economy by eliminating unnecessary fuel consumption, Mazda aims to deliver vehicles with exceptional environmental performance.