Up 60 PHEV_buses to begin shuttling students. [xfloat=right]http://www.cleanmpg.com/photos/data/501/Navistar_-_CE300_PHEV.jpg[/xfloat]Wayne Gerdes – CleanMPG – April 20, 2009 Navistar’s IC PHEV-40 School Bus. Warrenville, IL. -- Continuing with its development of hybrid commercial vehicles, Navistar was selected by the U.S. Department of Energy to participate in a project that will develop and deliver energy-efficient and environmentally friendly PHEV school buses. The DOE selected Navistar for a cost-shared award of up to $10 million—half of the total projected cost. As part of the PHEV Technology Acceleration and Deployment Activity program, Navistar will develop and deploy 60 PHEV buses to fleets across the nation during a multi-year program. “Navistar is proud to work with the Department of Energy on a project that will help reduce fuel consumption and emissions while reducing the country’s dependence on foreign oil,” said Daniel C. Ustian, Navistar chairman, president and chief executive officer. “By using plug-in electric vehicle technology in school buses, we have the privilege and opportunity to allow a generation of U.S. children to grow up with the expectation that, as part of their everyday commute to school, electric transportation is a reality.” Navistar’s IC Bus is the only bus manufacturer that currently offers a PHEV school bus. In the proposed project, Navistar will work to further develop the plug-in hybrid bus into a vehicle capable of all-electric drive for extended periods. This proposed vehicle will have engine-off driving capability, saving fuel and reducing emissions while traveling on electricity only. “These projects will help move technologies from the laboratory to the marketplace by improving their durability, reducing their costs, and validating their performance in real-world settings,” Energy Secretary Steven Chu said in a statement released on Friday. Details of IC Bus’ Charge Depleting 10AHJ The system includes a 25/80kw AC Induction motor mounted behind the transmission. The formal name for this is known as a Post-Transmission Parallel Hybrid System. The system captures energy from regenerative braking to recharge the batteries as well as reducing the load on the vehicle brakes for an improvement in brake life. The Induction Motor and the Hybrid Controller are cooled with a dedicated radiator system that utilizes standard red (OAT) coolant. This motor is environmentally sealed. When the Charge Depleting system is specified then the batteries are also cooled. There is a Battery Care Unit (BCU) that monitors the batteries for voltage, state of charge, amp hours, kilowatt hours and temperature. It is also capable of supporting differing battery technologies. The Safety Disconnect Unit (SDU), is controlled by the BCU and it connects and disconnects the battery pack during charging. It also provides surge protection and disconnect capability should a ground fault occur. An advantage of the parallel system is it allows the vehicle engine and transmission to drive through the electrics should a failure occur so the vehicle remains fully drivable. The batteries are housed in a split pack based on the school bus fuel tank cage design. Performance: Depending on the route, fuel mpg improvement is up to 70% better for Charge Depleting PHEV systems. Emission improvements vary with the pollutant being measured and has shown up to a 90% improvement at times on Particulate Matter, again, this is load and operating condition dependent. IC PHEVs utilize a larger battery pack based on advanced battery chemistry (Li-Ion) and are integrated within the hybrid system cooling package. They provide stored energy intended to be drawn down over the driving cycle subsequent to an overnight charge. The PHEV packs can be drawn down to approximately a 25% SOC. Subsequent to being drawn down; the vehicle will start to recharge the batteries as a std. HEV with a 20% to 50% fuel gain possible for the remainder of the route. This initial pack draw down takes place over the first 40 miles. It is also "tailorable," allowing the system to draw down quicker and provide greater mpg improvement or a sorter amount of miles, or drawn down more slowly resulting in a lower mpg improvement, but over a greater mileage range. The depleting cycle is a direct result of the software programming within the Hybrid Control Unit.