Author:
Elango Pradeev,Mathivanan Arulkumaran,Kakani Raghav,Das Himadri B.,Asvathanarayanan Ramesh
Abstract
<div>In Asian countries, small two-wheelers form a major share of the automobile
segment and contribute significantly to carbon dioxide (CO<sub>2</sub>)
emissions. Hybrid drives, though not widely applied in two-wheelers, can reduce
fuel consumption and CO<sub>2</sub> emissions. In this work three hybrid
topologies, viz., P2 (electric motor placed between engine and transmission), P3
(electric motor placed between transmission and final drive), and power-split
concepts (with planetary gear-train) have been modeled in Simulink, and their
fuel consumption and emissions under the World Motorcycle Test Cycle (WMTC) have
been evaluated. A physics-based model for the Continuously Variable Transmission
(CVT) was used which is capable of predicting its transient characteristics. A
map-based fuel consumption model and a Neural Network (NN)-based transient
emission model were used for the engine. The NN-based transient emission model
avoids the need to model the air path and fuel path in transient conditions,
which is time consuming. The fueling characteristics of the Engine Control Unit
(ECU) in transients need not be known if an NN model is built and tuned with
sufficient experimental data. Several transient experiments were performed with
speed-load profiles similar to the WMTC for tuning the NN emission models.
Simulation results show that the P2 hybrid, P3 hybrid, and power-split drives
have fuel economy benefits of about 27%, 37%, and 49%, respectively, compared to
the conventional powertrain. However, nitrogen oxides (NOx) emissions are much
higher for the hybrid powertrains due to the operation of the engine at higher
load ranges for efficiency but are still within the prevailing BS6 Indian
emission limits. A significant portion of the wheel energy input can be
recovered through efficient regenerative braking in the WMTC. This will be even
more significant under peak traffic city driving conditions. The belt losses in
the CVT significantly reduce the potential benefits of the hybrid powertrain,
and hence, an efficient transmission to replace it will be beneficial.</div>
Subject
Fuel Technology,Automotive Engineering,Automotive Engineering