Dutch company e-Traction of Apeldoorn, a European integrator of low-floor fleet buses, recently handed over the first of two e-Busz electric drive buses-featuring a third-generation wheel hub motor-to the Rotterdamse Elektrische Tram (RET), Rotterdam's public transportation authority.
The e-Busz is a VDL Bus & Coach Citea CLF bus converted with the third generation of the e-Traction system, developed with funding and licenses provided by Freerider Ltd. and by e-Traction Europe B.V., a wholly-owned subsidiary of e-Traction Worldwide S.C.A. The third-generation system in the
e-Busz differs from its predecessor in a number of areas.
The new system is designed around the newly developed, more powerful, SM500/3FE wheel hub motor units for a greater range of missions; a redesigned Universal Rear Axle to compensate for the greater depth of the wheel hub systems; more powerful U27 XP Lithium-ion batteries from Valence Technology for greater storage and higher instant on demand energy availability. Roughly doubled has been the output of the generator section of the Auxiliary Power Unit (APU) using the more powerful SM350/2AL direct-drive system as the DC power producing generator. It is integrated in a diesel-powered auxiliary power supply unit which has been completely rebuilt. Together with this APU the major sub systems such as the air compressor for the brake and suspension system, the power steering pump, and the ACCU are now all enclosed in a silent container that is mounted on rails and can be removed with quick-connects for maintenance. With this unit replaced the bus returnes to revenue service in about one hour.
The SM350/2AL system is slightly (100 millimeters) longer than its predecessor, to make room for additional permanent magnets and a larger rotor. This small dimensional increase enables it to produce double the amount of torque. Aside from offering double the torque, as a generator it can also produce twice the amount of energy (all else being equal).
Larger than its two predecessors, TheWheel SM500/3, is a direct-drive synchronous electric wheel hub system. The built-in CAN open system regulates the also built-in inverters to produce exactly the required power to ensure optimum operation of the synchronous direct drive traction motor. The SM500/3FE is being developed for high torque applications (e.g., 3,000 to 3,750 Nm) such
as steep climbs and/or heavy vehicles.
As the surface area of the permanent magnets was increased by an additional 50% compared to TheWheel SM500/2, the approximate performance in key parameters will also increase by 50%, while maintaining the same diameter. TheWheel and still be fitted with the same super-single tires placed on the e-Traction Bus and the Whisper.
The Valence Li-ion battery pack uses 12.8V, 138Ah U27 XP Lithium-ion batteries from this manufacturer. Specific energy is 91 Wh/kg, and energy density is 148 Wh/L. Maximum discharge is 300A.
Upon successful completion of in-service testing by RET, the city of Rotterdam is expected to purchase additional e-Busz buses to integrate into its fleet of 238 diesel transit buses.
