Design & Technology / Product
Forte LPI Hybrid Development Story August 21st, 2009
By Kim, Wan Seung
R&D Strategy team
Independent development – creating something out of nothing
The debut of the Forte LPi Hybrid demonstrated Kia’s ability to independently develop hybrid technologies. The list includes hardware and related software such as the electric motor which provides additional driving power, the battery that stores electric energy, the inverter which supplies and controls the battery’s high voltage power to the electric motor, and the converter which changes the battery’s high voltage to 12V.
Engineers gambled everything on the development of such hardware and software. Like their predecessors, researchers worked day and night toward their dream of developing independent technology. Hundreds of parts were designed over and over again. Engineers fought bitter cold weather in winter and struggled in the summer heat. They spent days, weeks and months reviewing 25,000 patents to avoid those registered by industry peers. In the end, they succeeded in developing key parts for the hybrid vehicle.
Lithium ion polymer batteries – the result of ceaseless R&D
The performance of an HEV is inextricably linked to the lifespan and storage capacity of batteries. This is the story of how Kia boldly decided to forego batteries from other companies and developed its own lithium ion polymer battery.
Batteries are an additional source of power for the hybrid car. They supply energy to the electric motor and store energy when braking or when the engine is in use. HEVs can use both nickel hydrogen batteries and lithium ion batteries, but due to technical constraints, the current HEV models in production use nickel hydrogen batteries. Lithium ion batteries began replacing nickel hydrogen batteries in mobile IT applications such as mobile phones and laptop computers since 2000 and are now the majority.
Kia decided to develop a lithium polymer battery instead of relying on imported nickel hydrogen batteries to secure a technical edge over peers. Development was jointly conducted with a local firm. Researchers had to create a battery that could withstand the most extreme environmental conditions while delivering over 10 times the reliability and durability as batteries used in small IT applications. Furthermore, researchers had to secure battery stability in acute physical, heat and electrical conditions. Cost competitiveness to counter mass produced nickel hydrogen batteries was another formidable challenge. However after years of R&D, researchers managed to complete the above-mentioned tasks. The lithium ion polymer battery in the Forte LPi Hybrid has three times the rated voltage of a nickel hydrogen battery (one cell basis) and is lighter in weight.
As such, output density was raised by 65% over nickel hydrogen batteries, while energy density was improved by about 35%. In terms of durability and lifespan, tests have been completed to ensure the battery supplies enough electric energy to a vehicle for over 300,000km. As for the most important consideration of safety, our researchers created a four-level safety net of vehicle controller, battery controller, pack structure and the cell’s safety design. Numerous tests recreating extreme conditions were conducted for complete assurance.
Environmental vehicles are evolving in diverse forms such as hybrid cars, plug-in hybrid cars and electric cars. The battery system, a storage device for electrical energy, is accordingly growing in prominence. With the world’s first application of lithium ion polymer batteries, Kia has secured leading technology for plug-in hybrid and electric vehicles and prepared the foundation to become a prominent presence in the eco-friendly vehicle market of the future.