Week-4 Challenge WOT Condition Part-2
What is the difference between the mapped and dynamic model of engine, motor and generator? How can you change the model type?
| Mapped engine | Dynamic engine |
| 1) The model uses a set of steady-state lookup tables to characterize engine performance. | 1) The model uses actual component data to characterize engine performance. |
| 2) The tables provide overall engine characteristics, including actual torque, fuel flow rate, BSFC, and engine-out exhaust emissions. | They are suitable to run diagnostics or controlling design parameters and are suitable for running |
| 3) The mapped engine model is generally faster while operating | 3) The dynamic engine model is usually slower while operating |
| Motor |
Generator |
| 1) A motor converts electrical energy into mechanical energy | 1) A generator converts the mechanical energy to electrical energy |
| 2) characteristics of a motor is the speed and torque curves are always positive which resembles work being done with respect to automobile | 2) in case of a generator the speed and torque curves are always negative which signifies that the work is being done on the automobile, which is used for regenerative braking |
| 3)The working principle of a motor is based on the current-carrying conductor that experiences a force when it is kept in the magnetic field. | 3)The working principle of a generator is based on electromagnetic induction. |
| 4)In a motor, the current is supplied to the armature winding. | 4)In a generator, the current is produced in the armature winding. |
to switch between the model type:
2)How does the model calculate miles per gallon? Which factors are considered to model fuel flow?
opening the hybrid electric vehicle multimode model reference model, after loading this model open the visualisation block there will be a block which has an output for the fuel economy
we can see that there are 3 inputs which govern the computation of fuel economy
1) vehicle speed
2) fuel flow
3) battery power
inside this block, we can see the following components used
1) vehicle speed: In this block, root mean square is applied and integrated and this value is fed into two element-wise gain where the values are converted from meters to kilometers and another gain from meters to miles and saturation block is used to limit the maximum and minimum input values.
2) fuel flow: In this block, the rate of fuel flow is converted into liters and the values are fed into the product block which with the vehicle speed will give the value of rate of fuel consumed per 100 km and the output of the battery power is fed into the input value of fuel flow as hybrid vehicles uses two types of energy sources battery and fuel, so that has to be computed in the calculation.
3) battery power: In this block the power is converted into KW and then this is converted into KW/gal equivalent value which is used by US. Battery rating is obtained by converting the power into KWh.
these parameters are used to calculate the values of miles per gallon
3)Run the HEV ReferenceApplication with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.
- open the HEV reference model and change the drive cycle from FTP-75 to WOT and run the default WOT condition to check for the behavior and then change values of WOT accordingly.
HEVMmReferenceApplication model
This model consists of a Hybrid vehicle which consists of a drive cycle which will be the main factor to how the vehicle will move and how the battery responds with different load requirements, and there is an environment block which will configure inputs such as grade, pressure, wind velocity and temperature.
the input values for WOT drive cycle
the following outputs are observed
Results
-we can observe that when the trace velocity attains max speed which is a theoretical value we can see huge transient effects in the speed of the engine, battery current, and engine torque as time passes by this transient effect is settled and attains steady-state values and follows the path described by the actual velocity.
-The battery discharges at a higher rate during the initial sudden acceleration which is mostly to overcome the environmental effects and to attain stable conditions and then the current follows the actual values of the drive cycle.
-The US fuel economy also shows how the vehicle works as per efficiency initially the fuel economy is low as vehicles the values of drive cycle the economy gets better.
Changing the values of Grade and Wind velocity and observing the changes caused by it
grade and wind velocity
Following outputs were obtained for the following values
comparing both the plots we can see a clean increase in transient behavior of the engine speed and engine torque and battery current and we can see that the US fuel economy is also affected due to changes in the environment, the vehicle takes a lot more time to attain stable condition as compared to the default value.
4)Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains.
simulation of hybrid electric powertrain the following plots were obtained
simulating pure electric vehicle having the same parameters as the hybrid electric powertrain
RESULTS:
1) Ev takes more time to reach max speed than HEV
2) after 50 seconds we can see that the HEV discharges more compared to EV from 80 to 62% and 80 to 74% respectively.
3) The US fuel economy of EV is higher than that of HEV for 50 seconds and still higher for EV after
4) at 50 seconds we can see that for HEV the currents below -200 A and for EV it does not fall below -200 A