2020 3rd International Conference On Green Energy And Environment Engineering
IOP Conf. Series: Earth
and Environmental Science
633
(2021) 012007
IOP Publishing
doi:10.1088/1755-1315/633/1/012007
4
output shaft are connected with mechanical coupling or any other linkage mechanism to combine and
transfer the power to the transmission.
In the simulation the engine and motor are arranged parallel to each other and unlike the figure 1 above
only
engine
is attached to the transmission and the battery is attached with the DC-DC convertor which
supplies electric current to electric motor to drive the shaft and the output shaft of both the transmission
and the motor are combined to combine the power produced by both the power sources. Due lack of
skills in MATLAB Simulink the control strategy unit was not developed in the powertrain model to
command the power source components according to the performance requirements of the vehicle.
Therefore, the method used here for knowing the power requirements of the electric motor to drive the
wheels was, the engine was kept On at constant throttle to deliver the power to wheels to maintain an
initial speed of the vehicle. And the electric motor is used to accelerate
the vehicle and maintain a
constant speed and then deaccelerate back to the initial speed which means electric motor was switched
On during the performance requirement and maintain the performance and then the electric motor is
switched Off and the vehicle is cruising with the engine power supplied to the wheels. The Electric
motor is managed with the speed command strategy made with help of MATLAB documentation and
the electric motor speed is increase and decreased with this strategy. And by changing the electric motor
speed the simulation results or the parameters are obtained such as electric power, shaft speed, battery
and fuel Consumptions, speed of the vehicle and the battery losses.
The components used here were an
engine
which was an ideal spark-ignition engine which has simple
parameters, and which has max speed of 7000 RPM and max power is 50 KW. And the Gearbox selected
here is a simple gearbox with constant efficiency 95%. The electricity is supplied from the battery where
it is stored, and it consists
of DC voltage source, internal resistance,
current and voltage sensor, the DC
voltage source is where the electricity is stored and used, the measure of the battery power is done by
the voltage and current sensors. And DC-DC convertor is used is an electric-mechanical device which
converts the voltage of DC current from high to low or low to high but here during the power conversion,
the voltage is increased because the motor requires more voltage current. and the electric motor is used,
it was a block set taken from the MATLAB Simulink library sources,
basically this converts the
electrical energy to the mechanical rotational energy and vice-versa when the engine powers the motor
it changes to the generator and charges the battery.
The electric motor and the speed command strategy
were made with help of the documentation of MATLAB. The electric
motor was commanded with
inputs in the speed command strategy to accelerate and deaccelerate accordingly at different step timing.
The wheel which were used here
were also a simple tire which doesn’t have any slip, and which were
connected by axle to the main driving shaft coming from the transmission. The Vehicle body dynamics
were also measured but assumption was made, the slope of road and the wind speed were not considered
and set to zero. the vehicle body was used to measure the normal force acting on the wheels and the
speed of the vehicle during different performance.
The
Speed
command
strategy here means to give the command to the electric motor to increase or
decrease its speed. So here four inputs are given first is to accelerate motor at a given step time 20s and
similarly second input command is given to stop acceleration at 70s to get a constant speed of the vehicle
and then the vehicle was deaccelerated by giving input at 120s and giving command to stop acceleration
at 170s and then the vehicle was running only on the engine. And these all input signal are combined to
one signal by integrating them then they are converted to RPM and it are measured by sensors connected
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