Week-4 Challenge WOT Condition Part-2

Pratik Mankar

1] What is the difference between mapped and dynamic model of engine, motor and generator? How can you change model type?

Mapped Engine

Mapped Engine is the default settings in powertrain blockset. It is used to measure to measure performance parameters of the vehicle by using standard lookup tables which are prefed to the system. This type of modelling is less accurate. The lookup tables value are based on the values of brake torque, commanded torque and engine speed. If any other parameter like Input engine temperature is selected then lookup table values are also a function of the temperature parameter. The data extracted from lookup tables are: air mass flow, fuel flow, emission data, exhaust temperature and efficiency. This data is used to find out other parameters which are needed by the end user.

Mapped engines represent macro engine behaviour as a set of lookup tables(brake torque,fuel flow,air masflow,exhaust temperature,efficiency and emissions) as functions of commanded load and measured engine speed. .Mapped engine models are suitable for analysis and design activities that do not require enigne subsystem dynamic characteristics,for example in egine and transmission powertrain matching analysis for fuel economy,emissions and performance trade-offs.

Dynamic Engine

This type of model uses real time data fed by the user at run time for modelling. This model is more accurate than mapped engine model. This type of model is used when the data of subsystems of a vehicle is required. We can calculate : Brake torque, fuel flow, port gas mass flow, exhaust temperature, exhaust mass flow rate and exhaust emissions.

Dynamic engine decompose engine behaviour into individual component models that account for engine dynamics,most notably intake airflow and turbo charger dynamics. Dynamics engine models are suitable for desiging control,estimator and diagnostic,algorthims that depend on dynamic subsysytem states,for example in closed loop AFR(air fuel ratio)control algorithm development.

Mapped Motor: The mapped motor works in torque control mode. This type of motor is used when the user requires a faster simulation and doesn't have the knowledge of motor parameters. The output torque and reference torque is compared and changes are made. Input torque or speed can be specified, electrical losses and maximum motor power and torque can be defined.

Dynamic Motor: In the dynamic motor a three phase interior permanent magnet synchronous motor (PMSM) is used. The block uses three phase input voltages to regulate the individual phase currents, allowing control of the motor torque or speed. This block is used when the user knows what parameters are to be used in that particular simulation. This motor is more accurate.

Mapped Generator: The mapped generator block is also similar like other blocks. Most of the data required is taken from the lookup tables corresponding to the given input parameters. Its simulation time is less.

Dynamic Generator: The dynamic generator involves user entering the parameters manually during the run time for their particular applications. The results take time and are more accurate.

To change the model from mapped to dynamic.

Suppose we plan to change the generator block from mapped to dynamic. Select GenDynamic then right click, then select 'Set as Label Model Active Choice'. Then double click 'GenDynamic'.

We can switch between mapped and dynamic engines byfollwing below procedured:

1 Open the ev model in simulink.

2 Enter the passenger car block by double click it.

3 Then Go to electric plant block.

4 Indside the motor block right click to find thr variant option.

2] How does the model calculate miles per gallon? Which factors are considered to model fuel flow?

Miles per gallon (mpg) & miles per gallon equivalent (mpge) for a conventional gasoline vehicle,the fuel efficiency is calculated via miles per gallon (mpg).however fuel efficiency for hybrid electric vehicles is calculated via miles per gallon equivalent(pge).mpg is the number of miles your car can drive per gallon of gas.figuring out an mpge rating is a littile more complicated.since engines that can use an alternative source of fuel cant be measured by liquid gallons of fuel,the mpge rating is calculated by figuring out the number of milles a vehicle can go using the same energy content as gallon of gas.the epa calculated that 33.7 kilowatt hours of electriccity is equivalent to one gallon of gas.

We Should go inside ev reference block that is perfomance calaculations.

inside this block will get actual mpg calculations.

Three Different inputs.

1.vehicle speed.

2.fuel flow.

3.battery power.

The vehicle speed inputs is in m/s which is converted into miles by multiplying with 0.000621371.

similarly the kilogram of fuel is converted into cubic meter by multiplying by1/(1000*0.739)

this cubic meter value is then converted into gallons by multiplying it with 264.172.the mile value and gallon value is used to find mpg of the vehicle.

now the battery value is initially converted from watts to kwh by dividing with 1000 and then to gallon equivalent by again dividing it with 33.7(sincw 33.7 kwh=1 gallon)

then divide the value by 3600 to get in per seconds and multiply by 0.00378541nto get the value in cubic meter per gallons.

3] Run the HEV Reference Application with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.

Input

here we have changed drive cycle to wot with a sample time 40 seconds

we have also altered environment block and changed wind speed to 25 m/s & grade to 10

Drive cycle source Result

Environment Block

Result

Conclusion

Plot 1:Trace velocity,target,actual:

Top velocity achieved =50.1 mph.

Time taken to accelerate = 29.034 sec.

Time taken to deaccelerate = 2.471 sec.

Plot 2: motor&engine rpm:

Top motor rpm=5712 rpm.

Top engine rpm = 5451 rpm.

Plot 3:motor& engine torque:

Maximum motor torque = 306.6 N-m.

Maximum engine torque = 174.7 N-m.

Plot 4:battery current:

The battery supply current is at its maximum value of 167 ampere when full throttle is applied by the user it reduces drastically to the value of negative 150 during deaccelaration of the vehicle.

Plot 5:battery SOC:

The battery soc will falls from 80 to 65 % during accelaration of vehicle and it increases slightly to 65 to 70 % during de accelaration due to regenerative braking.

Plot 6:fuel economy:

Maximum fuel economy achieved = 4.675

4] Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains.

Simulated Result of EV

Simulated Result of HEV

Conclusion

• The top speed is achieved by hybrid electric vehicle is more than that of EV.
• The battery current capacity of pure EV is much higher compared to that of HEV since in EV battery is the only driving unit.
• Higher fuel economy is achieved in case of pure EV.
• compare the simulated results of hybrid and pure electric powertrains Run Simulated.
• All result show and run program in simulation.