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Title: Optimal
brake torque distribution for a four-wheeldrive hybrid electric
vehicle stability enhancement
Author(s): D-H Kim, J-M Kim, S-H Hwang, H-S Kim
Source: Proceedings of the I MECH E Part D Journal
of Automobile Engineering
Volume: 221, Number 11 / November 2007 Pages 1357-1366
DOI: 10.1243/09544070JAUTO352
Publisher: Professional Engineering Publishing
Abstract:
Vehicle stability control logic for a four-wheel-drive hybrid electric
vehicle is proposed using the regenerative braking of the rear motor
and an electrohydraulic brake (EHB). To obtain the optimal brake
torque distribution between the regenerative braking and the EHB
torque, a genetic algorithm is used. The genetic algorithm calculates
the optimal regenerative braking torque and the optimal EHB torque
for the given inputs of the desired yaw moment and road friction
coefficient. Based on the optimal brake torque distribution, the
vehicle stability control logic proposed generates the desired direct
yaw moment to compensate the errors of the side-slip angle and yaw
rate by a fuzzy control algorithm corresponding to the driver's
steering angle and vehicle velocity. Performance of the vehicle
stability control logic is evaluated by comparison of the fixed
regenerative braking and the optimal regenerative braking for a
single lane change manoeuvre. It is found from the simulation results
that the optimal regenerative braking is able to provide the increased
recuperation energy compared with the fixed regenerative braking
while satisfying the vehicle stability.
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Title: Optimization
of control strategy for a single-shaft parallel hybrid electric
vehicle
Author(s): Kyoungcheol Oh, Junhong Min, Donghoon
Choi, Hyunsoo Kim
Source: Proceedings of the I MECH E Part D Journal
of Automobile Engineering
Volume: 221 Page: 554 - 565. May 2007
DOI: 10.1243/09544070JAUTO93
Publisher: Professional Engineering Publishing
Abstract: An optimal control strategy is obtained for a
parallel hybrid electric vehicle (HEV). Scale factors in weighting
the motor usage are selected as the control variables on how to
distribute the demanded vehicle power into the electric motor and
the internal combustion engine. Dynamic models of the HEV powertrain
are represented by state space equations. In order to find the optimal
control strategy, an optimization problem is defined, which finds
the optimal control variables to minimize the fuel consumption while
satisfying the constraint equations. The optimization problem is
solved using the HEV performance simulator developed in MATLAB Simulink
and the mathematical optimization sequential quadratic programming
algorithm which is based on FORTRAN for multi-variables design optimization.
It is expected that the optimization method proposed in this study
provides the control strategy of the HEV systematically, which minimizes
the fuel consumption.
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Title: Improvement
in fuel economy for a parallel hybrid electric vehicle by continuously
variable transmission ratio control
Author(s): H Lee; H Kim
Source: Proceedings of the I MECH E Part D Journal
of Automobile Engineering
Volume: 219 Page: 43 - 51. Jan 2005
DOI: 10.1243/095440705X6514
Publisher: Professional Engineering Publishing
Abstract: A continuously variable transmission (CVT) ratio
control algorithm is proposed to achieve the improved fuel economy
of the parallel hybrid electric vehicle (HEV) by considering the
HEV powertrain response lag. In this algorithm, the target CVT ratio
is modified by the vehicle velocity that is estimated after the
powertrain response lag. To estimate the vehicle velocity after
the response lag, an acceleration map is suggested. The CVT ratio
control algorithm is validated by the HEV bench tester. From experimental
results, it is found that the engine operation trajectory by the
modified ratio control algorithm is shifted to a more efficient
region compared with those by the conventional CVT ratio control
for the mild acceleration mode, which gives better fuel economy.
In addition, performance simulations for the federal urban driving
schedule are carried out to evaluate the effect of the response
lag on the HEV fuel economy using the HEV powertrain model. The
simulation results show that a better fuel economy can be achieved
as the response lag used in the modified CVT ratio increases. However,
in actual applications, a compromise between the fuel economy and
the acceleration performance would be required.
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Title: Circulating
mechanical power in a power-split hybrid electric vehicle transmission
Author(s): M Schulz
Source: Proceedings of the I MECH E Part D Journal of Automobile Engineering
Volume: 218 Page: 1419 - 1425. Dec 2004
DOI: 10.1243/0954407042707759
Publisher: Professional Engineering Publishing
Abstract: Recently, a new power-split hybrid electric vehicle drivetrain has been developed by the Corporate Research and Development Department of the Robert Bosch company and two research cars equipped with this powertrain have been built. Owing to the loop-like arrangement of the shafts in the newly developed Dual-E Transmission, circulating power can arise in this system. In general, circulating power leads to high mesh losses because the power transmitted by some components becomes greater than the input or output power. This paper presents a detailed analysis of circulating power in the Dual-E Transmission. It is shown that the solution of the energy balance equations is given by a linear combination of four basic power flows. The factors in this linear combination, however, cannot be uniquely determined from the energy balance alone. Therefore, the transmission kinematics and dynamics are dealt with in detail. Subsequently, a mathematical description as well as a graphical representation of the circulating-power-free operating range are derived. This elaboration provides a solid basis for the development of a fuel-efficient operating strategy.
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Title: Modelling
and analysis of powertrain hybridization on all-wheel-drive sport
utility vehicles
Author(s): G Y Liao; T R Weber; D P Pfaff
Source: Proceedings of the I MECH E Part D Journal of Automobile Engineering
Volume: 218 Page: 1125 - 1134. Oct 2004
DOI: 10.1243/0954407042274912
Publisher: Professional Engineering Publishing
Abstract: Four concepts of strong hybridization powertrains on all-wheel-drive sport utility vehicles are presented. These concepts enable conversion of conventional powertrains into strong hybrid powertrains with minimal tear-up to the existing architecture. The first concept incorporates an electric machine attached to the output side of a conventional transmission. The second concept is a strong input power-assist system, where the motor is packaged between the torque converter and the transmission. The third concept is similar to the second one, but the torque converter is replaced by a starting clutch. The fourth concept is a compound-input, power-split, electric-variable transmission (EVT). These concepts provide extensive hybrid functionality, such as motor-only drive, launch assist, and energy recuperation. Simulation results indicate that proposed strong hybrid concepts can result in fuel economy gains of 19-26 per cent over conventional powertrains.
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