Cummins Readies Reveal Of A 560-kWh BEV And 210-kWh EREV Powertrain For Transit Buses
Cummins has announced the expansion of its powertrain lineup for transit, shuttle and commuter buses by offering battery electric vehicle (BEV) and range extended EV (REEV) solutions.
The company intends to presents both platforms at the upcoming APTA public transportation show that opens on October 9 in Atlanta.
The base setup for the BEVs and REEVs are 70 kWh battery enclosures – and up to eight can be combined in the all-electric bus format, good for a total of 560 kWh and 224 miles (360 km) of real world range. The REEV version is designed for up to three batteries pack units (210 kWh) and 84 miles (135 km) range.
“Enhanced energy storage for both the BEV and REEV systems is achieved using Cummins’ high-density battery enclosure, which are compact and modular allowing for both on-roof and chassis integration. Cummins’ unique design fits into existing bus designs.
Cummins’ proprietary control technology enables the zero-emissions bus range to be extended by optimally managing subsystems, allowing the charge of the battery to be extended. Operational flexibility is also improved with fast recharge capability using a plug-in connection, as well as options for en-route charging when a pantograph or charge plate infrastructure is available.”
“The standard-size Cummins battery enclosure provides a 70-kWh storage capability with up to 8 enclosure units (560 kWh) suited for installation within the BEV bus. This enables a zero-emissions range of up to 224 miles on a single charge, with an energy consumption of 25 miles per gallon diesel, which provides significant cost reductions.”
Both the BEV and REEV powertrains will offer the same electric motor – with a peak output of 350 kW (225 kW continuous) and 3,400 Nm (1,850 Nm continuous).
The REEV version will of course also need a compact engine-generator, in this case rated at 150-kW (201-hp) via a 4.5-liter engine (downsized by about 50 percent in terms of displacement).
“Cummins REEV system has a battery pack of three enclosures (210 kWh) which can provide a zero-emissions range of up to 84 miles — a significant advantage over current hybrid bus capability. When the battery pack depletes to a low state-of-charge, the REEV system brings online a 150-kW (201-hp) engine-generator to recharge the batteries and continue operations with ultra-low emissions capability.
Compared to the standard diesel-powered bus, the REEV 4.5-liter engine is downsized by about 50 percent in terms of displacement and can achieve up to 10 miles per gallon, significantly lowering the carbon footprint. A power assist function is available from the battery pack whenever the system needs additional energy.
The REEV system’s ability to switch between shorter-range battery-only mode and extended-range generator mode allows transit authorities to geofence specific downtown areas by utilizing Cummins over-the-air connected technology. The REEV system also enables buses to travel significant distances beyond the city charging infrastructure.”
The BEV and REEV systems incorporate the same traction motor and power electronics to deliver a continuous torque output of 1850 N•m (1365 pound-foot), eliminating the need for gear shifting and dramatically reducing powertrain noise. When the vehicle requires additional tractive power during rapid acceleration or while climbing gradients, the system can deliver an instant peak torque boost of up to 3400 N•m (2508 pound-foot) for a short period.
Both systems provide a continuous electrical output of 225 kW (302 horspower), increasing to a peak output of 350 kW (469 horsepower) when it senses the need for a power boost. The high-voltage system operates at a nominal 660V when battery state-of-charge is around 50 percent.
Battery energy storage levels are boosted on-route by accepting “free” energy recovered through regenerative braking. On a frequent stop/start bus duty cycle, this could contribute the equivalent of 20 percent to the total state-of-charge.
Electrical energy is also exportable from the Cummins system to all electric-powered accessories featured on the bus, such as e-power steering, e-HVAC, e-air compressors and e-cooling fans, adding up to a typical 25-kW (33-horsepower) load at any one time. The electrical supply from the Cummins system can be both low-voltage DC and high-voltage AC, helping to simplify the installation and lower the cost of the e-accessories package.
The same electronic control module used on the popular L9, L9N and B6.7 bus engines is adapted for use as the BEV and REEV system controller, offering familiar diagnostics and the connectivity that bus operators experience today.”
Julie Furber, Executive Director, Electrification Business, Cummins Inc. said:
“The introduction of our new BEV and REEV systems will complement Cummins’ clean-diesel, near-zero natural gas and diesel-hybrid products to offer the broadest, most energy-diverse power portfolio in the bus industry. We are able to meet the needs of every transit route, every duty cycle and every emissions standard in the most cost-effective manner,”
Brian Wilson, Cummins General Manager — Global Bus Business said:
“A key focus in the design of both our BEV and REEV systems ensures the electrified architecture is modular and adaptable to enable an easier technology transition for bus manufacturers. This allows transit authorities to continue using the same preferred bus models and retain fleet commonality.”
“The new systems will be expertly serviced and supported by Cummins’ distribution network the same way we currently provide 24/7 support for our diesel-, hybrid- and natural-gas-powered fleets. This is an important factor for transit authorities, because as they adopt new technologies they can count on Cummins to help with a transition to BEV and REEV technology,”