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7 Hybrid and Electric Powertrain Technologies
Pages 201-232

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From page 201...
... , National Highway Traffic Safety Administration (NHTSA) , and California Air Resources Board have all published rules, proposed rules, and performed regulatory impact analyses that show a significant penetration of hybrid, plug-in hybrid, and battery electric vehicles is required in order to meet future light-duty vehicle fuel economy and greenhouse gas (GHG)
From page 202...
... Other hybrid systems employ different combinations of energy conversion devices such as an ICE and a hydraulic pressure accumulator storage system or a fuel cell propulsion energy system combined with an ultra-capacitor to store high levels of electric power transferred during vehicle braking and subsequent launch. The goal of a hybrid propulsion system is to manage energy flows most efficiently throughout the drivetrain system, thereby reducing fuel consumption and GHG emissions, by 1.
From page 203...
... Unlike the series HEV configuration, a single motor/generator unit can be used to drive the wheels or generate electricity during regenerative braking to recharge the battery. In a parallel HEV, the motor/generator can supplement the ICE during start-up or vehicle acceleration because both are coupled to the wheels.
From page 204...
... 7.1.2.4 Mild Hybrid with Stop-Start, Launch Assist, and Regenerative Braking A starter-alternator-type system may also be designed with somewhat higher power, torque, and energy storage capability. This would classify the system as a mild HEV, although the largest fuel consumption benefit is still derived from stop-start functionality.
From page 205...
... The so-called XL3® Hybrid Electric Drive System is compatible with Class 2, 3, 4, 5, and 6 vans and passenger wagons, commercial vans and shuttles, box trucks, and delivery vans. XL Hybrids reports that installation takes less than 6 hours per vehicle and the performance specifications are as follows: • System voltage, 259 V; • Lithium-ion battery, 1.8 kWh; 5 See http://www.hino.com/hino-trucks-hino-195h.html (accessed December 1, 2019)
From page 206...
... Also, regenerative braking can generate electricity through the normal drive motor, which is then stored in the battery or other energy storage system. An input-split system, shown in Figure 7-7, utilizes an engine, a power-split transmission, a generator, and a drive motor.
From page 207...
... These include 1. A single-mode power-split hybrid, where the first generator controls engine speed and the drive motor supplements any power needed to propel the vehicle; and 2.
From page 208...
... relatively short-route urban delivery or service applications and (2) vocational vehicles that travel to a job site and then perform operational functions where use of electric power instead of operating the combustion engine can significantly reduce liquid fuel consumption.
From page 209...
... HYBRID AND ELECTRIC POWERTRAIN TECHNOLOGIES 209 FIGURE 7-8  Odyne hybrid system PHEV electric utility service truck. SOURCE: Odyne Hybrid Systems, LLC (2014)
From page 210...
... However, application for light-duty BEVs are somewhat less rigorous than for commercial vehicles, based on the power transfer requirements. Therefore, commercial viability is still a challenge for commercial electric vehicles due to the large size of the battery packs.
From page 211...
... operates as a generator during braking. This regenerative braking feature can provide significant improvements in fuel consumption during operating cycles which reflect a high number of acceleration and subsequent braking modes.
From page 212...
... . The three hydrogen fuel cell buses did not contain energy storage, demonstrated fuel economy worse than diesel buses, and exhibited miles between road calls (MBRC)
From page 213...
... . 7.1.2.11 Nikola Hydrogen Fuel Cell Class 8 Tractor and Day Cab In December 2016, Nikola Motor Company announced the introduction of a hydrogen fuel cell–powered Class 8 tractor which charges a 320 kWh battery pack for over-the-road service (see Table 7-3 for more technical specifications)
From page 214...
... 7.1.2.12 Hydraulic Hybrid Powertrain Vehicles Due to the level of power which is potentially required to brake or propel a medium- or heavy-duty hybrid vehicle, the size, cost, and weight associated with batteries, battery packs, electric motors, and other related equipment can become challenging. Especially for duty cycles in which there are a significant number of braking and subsequent acceleration events, hydraulic hybrid powertrain systems have demonstrated high regenerative braking efficiencies (>70 percent)
From page 215...
... . TABLE 7-3  Additional Specifications Reported for Nikola One Motor type 800V AC motors Battery capacity and chemistry 320 kWh lithium ion Transmission Two-speed automated with direct drive and low-noise gears Drive system type 6×4 four-wheel drive Active descent control Regenerative braking Cooling Biodegradable non-electrically conductive liquid coolant SOURCE: Nikola Motor Company.
From page 216...
... as it cycles on and off, thereby minimizing fuel consumption. On the other hand, in a parallel system, the engine can drive the wheels through a mechanical transmission with gear-drive efficiencies greater than 90 percent.
From page 217...
... According to Parker12 there are some 200 refuse trucks currently using the RunWise system in commercial service and Parker claims up to 47 percent reduction in fuel consumption for refuse truck applications with a very high level of acceleration and braking cycles during normal use. This type of service, similar to city bus operating cycles, represents perhaps the best use of HHV technology because of the high efficiency of hydraulic systems during high power transfer for relative short periods of time during acceleration and subsequent braking to a stop.
From page 218...
... The fuel consumption and associated GHG reductions with such parallel hydraulic launch assist systems all appear to be in the 15 to 25 percent reduction in fuel consumption performance region. As the level of technology increases, to include power-split or advanced parallel-series systems, such as the Parker RunWise system, improvements in fuel consumption are seen to achieve levels of 35 to 40 percent, in addition to reduced criteria pollutants such as NOx and CO, and significant improvements in brake system life, due to greatly reduced loads on the foundation brakes on commercial vehicles fitted with regenerative braking.
From page 219...
... HYBRID AND ELECTRIC POWERTRAIN TECHNOLOGIES 219 FIGURE 7-12  Parallel, hydraulic hybrid regenerative braking and launch assist system for Class 3 through 6 commercial vehicles. SOURCE: Image used by permission of Lightning Hybrids, LLC.
From page 220...
... Use cases involving a high frequency of braking cycles, such as refuse trucks or urban buses, can gain significant benefits through regenerative braking, where the size of the energy storage system can be somewhat limited in size to recover primarily only the braking energy and then launch the vehicle. Other applications, such as urban delivery trucks, may choose to incorporate larger energy storage systems and optimize total route operational efficiency with a combination of regenerative braking and periods of operating the ICE and higher load levels, to minimize carbon-based fuel consumption.
From page 221...
... belt-starterClass 2b-3 Heavy-duty pickup and van Urban + highway 3.5 generator (BSG) Integrated S/S with regen/launch Class 2b-3 Heavy-duty pickup and van Urban + highway 10 assist Class 2b-3 Parallel strong hybrid Heavy-duty pickup and van Urban + highway 20 Class 4-5 12 V S/S BSG Vocational vehicles Urban + highway 3.5 Integrated S/S with regen/launch Class 4-5 Vocational vehicles Urban + highway 16 assist Class 4-5 Parallel strong hybrid Vocational vehicles Urban + highway 20 Class 4-5 12 V S/S BSG Delivery trucks Urban delivery 3.5 Integrated S/S with regen/launch Class 4-5 Delivery trucks Urban delivery 20 assist Class 4-5 Parallel strong hybrid Delivery trucks Urban delivery 25 Class 6-7 12 V S/S BSG Vocational vehicles Urban + highway 3.5 Integrated S/S with regen/launch Class 6-7 Vocational vehicles Urban + highway 16 assist Class 6-7 Parallel strong hybrid Vocational vehicles Urban + highway 20 Class 6-7 12 V S/S BSG Delivery trucks Urban delivery 3.5 Integrated S/S with regen/launch Class 6-7 Delivery trucks Urban delivery 20 assist Class 6-7 Parallel strong hybrid Delivery trucks Urban delivery 25 Class 8 12 V S/S BSG Vocational refuse truck Urban accel/brake 3.5 Integrated S/S with regen/launch Class 8 Vocational refuse truck Urban accel/brake 22 assist Class 8 Parallel strong hybrid Vocational refuse truck Urban accel/brake 30
From page 222...
... 7.5 ADVANCES IN TECHNOLOGY AND COST REDUCTION OF ELECTRIC MOTORS AND POWER ELECTRONICS FOR HYBRID AND BATTERY ELECTRIC VEHICLES As identified in the preceeding sections of this chapter, significant progress has been made in the reduction of battery cell and pack costs for use in light-duty hybrid and battery electric vehicles. A rather detailed discussion on battery technology and projected improvements is included in Chapter 8.
From page 223...
... . As a gauge for individual subsystem cost reduction challenges, the 2015 production costs for the electric traction motors and power electronics for a typical passenger car (3,500 to 4,000 pounds vehicle weight)
From page 224...
... Lower system cost: While WBG semiconductors are generally higher cost than silicon, system-level cost reductions are sometimes possible through the use of WBG by reducing the size and/or costs of other components such as passive inductive and capacitive circuit elements, filters, and cooling. FIGURE 7-14 DOE Electric Drive Technology Program electrified powertrain technical and cost targets.
From page 225...
... WBG-based Power Electronics Non–Rare-Earth Motors Power Density Silicon-based Power Electronics Payoff: Reduced Rare-Earth Content in Motors Lower cost and increased power density enables greater adoption, drive system Silicon-based Power Electronics scalability, and flexibility for Rare-Earth Permanent Magnet Motors vehicle applications On-Road Technology 2015 2022 2022 System 4x cost 35% size 40% weight 40% loss $8/kW reduction reduction reduction 1.4 kW/kg reduction 4 kW/L 94% efficiency Innovation is necessary to accelerate vehicle electrification:  WBG power electronics to improve power density and reliability.  Advanced magnets for electric traction drive motors.
From page 226...
... 7.6 COST AND EFFECTIVENESS OF HYBRID AND ELECTRIC MEDIUM- AND HEAVY-DUTY VEHICLES The manufacturing cost of hybrid and all-electric drive medium- and heavy-duty powertrains is dominated by the costs of the related battery packs, electric motors, power electronics, and associated cooling, wiring, and electronic controls systems. As discussed in Chapter 8, significant reduction in costs for battery cells and packs for light-duty vehicles has been achieved.
From page 227...
... The relative fuel consumption improvement values were derived from several sources including the first medium- and heavy-duty fuel economy report (NRC, 2010a) , published results from the EPA and NHTSA RIAs, and the analyses conducted for the committee by Southwest Research Institute.
From page 228...
... Year or or % Reduction in Class 2b and 3 Class 4 Vocational Class 5 Vocational Class 5 Delivery Vehicle Class FC Van and Pickup Vehicles Class 4 Delivery Trucks Vehicles Trucks Technology   Low Cost High Cost Low Cost High Cost Low Cost High Cost Low Cost High Cost Low Cost High Cost Non-hybrid 2015 $1,190 $1,210 $1,710 $1,725 $1,710 $1,725 $1,710 $1,775 $1,710 $1,775 Enhanced accessories 2022 $477 $540 $724 $800 $724 $800 $744 $850 $744 $850 % Reduction 3.50% 3.50% 3.50% 3.50% 3.50% 3.50% 3.50% 3.50% 3.50% 3.50% 12 V stop-start in FC   2030 $422 $481 $650 $719 $650 $719 $670 $739 $670 $739 RIA integrated 2015 $5,150 $5,175 $9,800 $9,850 $9,800 $9,850 $9,800 $9,900 $9,800 $9,900 Mild hybrid regen/ 2022 $2,208 $2,435 $4,584 $5,010 $4,584 $5,010 $4,584 $5,060 $4,584 $5,060 launch % Reduction 10% 10% 16% 16% 22% 22% 16% 16% 22% 22% With stop-start in FC   2030 $2,005 $2,201 $4,240 $4,602 $4,240 $4,602 $4,260 $4,652 $4,260 $4,652 Parallel strong hybrid 2015 $12,250 $12,350 $17,100 $17,300 $17,100 $17,300 $17,100 $17,500 $17,100 $17,500 SHEV (18-22% 2022 $5,094 $5,730 $7,426 $8,320 $7,426 $8,320 $7,426 $8,520 $7,426 $8,520 pickup and van) %Reduction 20% 20% 20% 20% 25% 25% 20% 20% 25% 25% Electric drive in FC   $4,640 $5,178 $6,785 $7,562 $6,785 $7,562 $6,785 $7,762 $6,785 $7,762
From page 229...
... Year Class 8 Vocational Vehicles Class 8 Vehicle Class or % Gain Class 6 and 7 Vocational Vehicles Class 6and 7 Delivery Trucks (Refuse) Tractor-Trailers Technology   Low Cost High Cost Low Cost High Cost Low Cost High Cost     Non-hybrid 2015 $2,150 $2,180 $2,150 $2,180 $3,300 $3,350   Enhanced accessories 2022 $891 $1,000 $891 $1,000 $1,389 $1,565   12 V stop-start (% gain)
From page 230...
... Due to the much higher vehicle weights for commercial vehicles compared to passenger cars, the relative size of battery packs, electric motors, power electronics, and the rest of the hybrid-related system is much larger. As a result, the total system costs, related by cost per kilowatt of power or the necessary kilowatt-hour levels, are much larger, as shown in the table.
From page 231...
... Finding: Current R&D activities being undertaken by DOE and its industry partners are focused on the cost reduction of electric motors/generators for use in light-duty hybrid and electric vehicles. Due to the much higher torque requirements for medium- and heavy-duty drivetrains, the technical approaches for light-duty electric motor cost reduction may not directly carry over to the commercial vehicle space.
From page 232...
... 2016. "Overview of the DOE VTO Electric Drive Technologies R&D Program," Presentation at the 2016 DOE Vehicle Technologies Office and Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting about Electric Drive Systems.


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