Comparison of Gearless Hybrid Transmissions for a Medium-Duty Truck

Gearless configurations are of interest to truck applications since they can avoid high maintenance of the gear based transmissions. This paper compares three different hybrid topologies for a medium duty truck, which contain two electric machines and no gear transmissions. Those powertrains are one series, one series-parallel using a double rotor machine and one series-parallel using a clutch. The powertrains are described in the Energetic Macroscopic Representation (EMR) formalism and controlled by global optimization. Using the series powertrain as a benchmark, simulations show that the two series-parallel could improve the fuel economy by 7%-14% according to different driving cycles.