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Optimization of a PHEV Powertrain for Heavy-Duty Vehicle Applications

Company Name: Efficient Drivetrains, Inc.
Program Office: Vehicles
Location: Milpitas, CA
Email: Jean-Baptiste Gallo, Product Manager;
Award Amount: $140,000
Project Term: 12 months
Project Status: Active
Participating Lab(s): National Renewable Energy Laboratory


Heavy-duty vehicles represent only 5 percent of the vehicles on the road in the U.S., but are responsible for 30 percent of vehicle carbon dioxide emissions and 36 percent of vehicle particulate emissions. Advanced powertrain technologies such as plug-in hybrid electric vehicles (PHEVs) can provide significant fuel economy improvement and criteria pollutant emissions reduction. A PHEV powertrain is an ideal no-compromise solution for many fleets, offering advantages compared to options that limit range (including all-electric trucks) or refueling options (including fuel-cell trucks).

While most of Efficient Drivetrains, Inc.'s (EDI's) competitors focus on simpler, electric-vehicle-only powertrains, EDI's PowerDrive™ system combines two sources of energy — electricity and diesel — into a compact, lightweight, high-efficiency four-mode, series-parallel PHEV drivetrain, offering the benefits of parallel and series hybrid electric operations. The full integration of the EDI PowerDrive™ system with the internal combustion engine is a significant challenge that requires modeling, simulating, and testing expertise, and access to research and testing facilities. While larger original equipment manufacturers can tap into generous research and development budgets and use in-house testing facilities, smaller companies like EDI have limited time and resources to develop extensive R&D programs, and have few options for testing heavy-duty vehicles.

Collaboration with the National Renewable Energy Laboratory (NREL) will move the PowerDrive™ from technology readiness level (TRL) 7 to TRL 8, dramatically accelerating the commercialization timeline and resulting in the first commercially available heavy-duty class 6 PHEV. Testing will enable EDI to increase truck performance, reduce greenhouse gas emissions, reduce lifecycle energy use, and secure global leadership in the market.


The EDI PowerDrive™ is a compact, lightweight, and highly efficient four-mode series-parallel PHEV drivetrain that integrates two electric motors into the drivetrain of an internal combustion engine. This advanced series-parallel PHEV system can deliver all of the benefits of both parallel and series hybrid electric vehicle systems, offering an impressive improvement in fuel economy in comparison with standard hybrid electric vehicle systems.

Several aspects of EDI's technology and design set it above its competitors. EDI's PowerDrive™ system design focuses on reducing complexity, weight, and cost. The technology is adaptable to a unique inline form factor, allowing the drivetrain to be integrated into any light-, medium-, or heavy-duty application or vehicle design. Specifically, the proposed drivetrain integrates all motors and clutches while fitting within the space of a conventional drivetrain. This expedites time to market, and minimizes development costs.



Working with NREL will help EDI answer a critical need in the heavy-duty vehicle market, as there are currently very few PHEV solutions for heavy-duty vehicles. Specifically, this project would help lead to the following market and business results:

  • Competitive advantage: The proposed work would help EDI bring its PowerDrive™ system to the heavy-duty vehicle market, securing EDI's competitive advantage through early entrance into that market.
  • Accelerated commercialization timeline: EDI estimates that NREL's assistance will accelerate the commercialization of its heavy-duty PowerDrive™ system by at least one year.
  • Company growth: Rapidly achieving product commercialization will lead to significant company growth in terms of annual sales, job growth and cost reduction.

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