Extreme Hybrid™ Technology: Drivetrain Overview

The Extreme Hybrid™ is the first practical drive train for a Plug-in Hybrid Vehicle. Its two-part energy storage system combines Lithium-ion batteries with ultracapacitors. This “hybrid within a hybrid” energy storage system exploits the strengths of lithium-ion batteries (light weight and high energy density) and ultracapacitors (small size and high power density). Batteries alone, have high energy density but they must be greatly oversized in today’s hybrid vehicles to avoid deep discharges. Battery-only hybrids also require a powerful internal combustion engine for hill climbing and acceleration.

Adding ultracapacitors with their high power density and high cycle life allows the Extreme Hybrid™ Plug-in to achieve top speeds and rapid acceleration in electric-only mode equal to a conventional hybrid. The Extreme Hybrid™ design allows for a smaller internal combustion engine while preserving high vehicle performance.  For a typical daily commute of 40 miles round trip, an Extreme Hybrid™ vehicle does not use its internal combustion engine at all.

Extreme Hybrid™ Drive Train

The Extreme Hybrid™ Plug-in drive train is composed of five primary subsystems: (1) advanced lithium batteries recharged at night with off-peak power from the grid; (2) Fast Energy Storage™ using ultracapacitors for acceleration and regenerative braking; (3) advanced power electronics and control software; (4) internal combustion engine; and (5) electric traction motor and generator. In miles per petroleum gallon, the XH-150™ plug-in hybrid SUV achieves 150 MPPG.

Extreme Hybrid™ Drive Train 3D Animation

Title: "Extreme Hybrid™ Drive Train 3D Animation"
Duration: 4:18
Description: This 3D animation with voiceover demonstrates how the XH-150 works when operated in all-electric mode. By storing energy in Ultracapacitors and using them to deliver the fast energy required for acceleration, the XH-150 is able to accelerate quickly, without stressing the Lithium Ion Batteries or causing resistive heating to occur.

How the XH™ differs from Conventional Hybrids

The Extreme Hybrid™ vehicle differs from today’s popular hybrids in several ways.  The most important are the increased capacity of the battery, the ability to recharge the battery from the electric power grid, and, equally important, the presence of a second Fast Energy Storage™ component that enables rapid acceleration and greater regenerative braking capability. The Extreme Hybrid™ requires the seamless transfer of power between a number of different devices, including traction motors, generator, charging system, and ancillary loads.  The integration and control issues presented by this system were similar to those which AFS Trinity addressed and mastered in the development of fast energy storage and power management systems. The technologies crucial to the Extreme Hybrid™ are batteries, Fast Energy Storage™, and power and control electronics.

How the Extreme Hybrid™ Achieves 150 MPG

Extreme Hybrid™ Energy Storage Detail

AFS Trinity selected Lithium-ion battery technology for its minimum weight per unit of stored energy.  The life of lithium batteries, however, is shortened by high current discharge and recharge during acceleration and braking.  The presence of a high power density ultracapacitor will buffer the battery from these high current events and extend battery life to a ten year, 150,000 mile life in an Extreme Hybrid™ SUV.

Li-ion battery technology has advanced dramatically over the past ten years, and this rate of advance is expected to continue, bringing it to a high stage of development by the year 2010, concurrent with the completion of development of the Extreme Hybrid™.  Power Electronics prices have dropped 15% per year for a decade, and this trend is expected to continue, which will also contribute to Extreme Hybrid™ vehicle affordability in 2010.  Ultracapacitor prices have dropped a factor of two every two years for the past six years, and the price drop is projected to continue through 2010 and beyond.