Allison EP System

The Allison E^P System is a two-mode compound split parallel hybrid electric system for diesel vehicles. The system is comprised of a a dual pulse interval modulator (DPIM2), Panasonic nickel metal hydride (NiMH) enrgy storage batteries, a control modual, and an electric drive called the E^V Drive.

The DPIM2 unit is usually located behind the NiMH batteries on the roof. It converts engery that is transfered between the drive/generator, which uses and produces alternating current (AC), and the batteries, which store direct current (DC). The energy stored in the batteries is produced through the generator connected to the diesel engine and though regenerative braking. Prior to the launch of the 2010 model, the EP System used Allisons DPIM. This was replaced by the current DPIM2 which has more robust internal hardware and enhanced redundancy for greater reliability.

The E^V Drive is an infinitly variable transmission in common with the Allison Bus Series. The E^V Drive is equipped with planetary gears and clutches and electronic solenods and motor/generator. The gerator/motor acts as variable clutches and controls the the planetary components.

Allsion announced in December 2009, that for 2010, the E^P System for buses and coaches will feature new and improved components for greater reliability, durability and performance.The 2010 E^P System will use Allison's Fourth Generation Electronic Controls which has greater processing power and memory capability. It also features a revised DPIM, improved enegery storage system (called ESS2), and updated 2010 E^V Drive for 2010-compliant engines.

Type	Max. input tower of EV Drive	Max. input torque of EV Drive	Mass of EV Drive (dry)
EP40 System	280 hp (209 kW)	910 lb-ft (1235 Nm)	919 lbs (417 kg)
EP50 System	330 hp (246 kW)	1050 lb-ft (1420 Nm)	919 lbs (417 kg)

References

• Allison E^P System, allsisontransmission.com, retrieved on 2009-10-03