Inclusion of real physics based dynamics instead of conventional charts and
maps, while capturing the transient behavior of the overall powertrain is the primary
objective of this research effort. The multi-body model of the longitudinal car is
described in detail, including mathematical models of tyres, suspensions, aerodynamic
behaviour and continuous variable transmission (CVT). The PMSM and PMSG along
with DC/AC, AC/DC are modeled in the d - q frame. A novel frictional torque function,
predicting all mechanical and electrical losses except resistance loss, is proposed. The
results of the proposed frictional torque function compare well with the results obtained
from empirical sources. Average models for AC/DC, DC/AC and DC/DC converters are
used to ensure the simplicity and feasibility of the simulation in acceptable time scale.
Bidirectional converters fed-back the recaptured mechanical energy during regeneration
to the battery. A switching-frequency dependent average model for soft-switching
isolated DC/DC converter is used in this research. A generic dynamic Li-ion battery
model has been chosen which expresses the electrochemical parameters of the battery
directly in terms of electrical parameters of the circuit.
A control oriented, fast and simple 0D model of the turbocharged diesel engine,
combining mean value model and filling and emptying models has been presented in
this work. Inlet manifold and exhaust manifolds are modeled as filling and emptying
model, engine cylinder dynamics with mean value model, engine torque as a three
dimensional map of indicated torque (Teng = f (ωeng,λ)), engine speed ωeng and air-fuel
ratio λ, and flow characteristics of the compressor and turbine are modelled with mean
value model. A novel control mechanism is proposed to control the fuel mass flow rate
and relative air-fuel ratio. Simulation results of the present engine model are validated
against a high-fidelity commercial Ricardo-wave model of the same engine.
A novel DC-link control mechanism is proposed to simulate the transient operation
of the series HEV powertrain during different modes of operation. The supervisory
control is implemented to meet the driver’s demand for the traction power, at the same
time avoiding over-discharging of the battery below certain threshold level, and optimizing
the drive train efficiency, fuel consumption and emissions. On the basis of
thermostat control and power follower, a novel “load follower” supervisory control
strategy is proposed in the present work. A PI controller based driver model is developed
and performance seems satisfactory while tracking the standard NEDC cycle.
Simulation results are validated by energy balance computations and available transient
and steady state data points for individual components as well as the overall powertrain.
The research has successfully achieved the goal of developing a complete model for a
series hybrid powertrain while capturing the transient performance of the all the components
involved in the powertrain with module based, control oriented and forward
facing modelling approach.