Week-4 Challenge WOT Condition Part-2

 1>>Ans: Mapped Engine: Mapped Engine is the default setting in the powertrains blockset. It is used for the measure to measure the performance parameters of the vehicle by using standard lookup tables which are preferred to the system. This type of modeling is less accurate. The lookup tables value are based on the values of brake torque, command torque, and engine speed. If any other parameters like input engine temperature are selected then lookup tables are also a function of the temperature parameters. 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-users.

Dynamic Engines:   This type of model uses real-time data feed by the user at run time for modeling. This model is more accurate than the 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, Gas Mass Flow, Exhaust Temperature, Exhaust Mass Flow Rate, and Exhaust Emissions.

Mapped Motor: The Mapped Motor works in the torque control model. This type of motor is used when the user requires a faster simulation and does not have the knowledge of motor parameters. The output torque and reference torque are 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 to other blocks. Most of the data required are taken from the lookup table corresponding to the given input parameters. Its simulation time is less.

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

Now to change the model from Mapped to Dynamic is as follows:

>> Go to Modelling ----> Variant Manager.

Now When the plan is to change the generator block from Mapped to Dynamic.

Select GenDynamic---> Right Click ----->select 'Set as Label Model Active Choice'. Then double click "GenDynamic"

 2>> Ans: 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 drive per gallon of gas. Figuring out a mpge rating is a little 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 miles, a vehicle can go using the same energy content as a gallon of gas. The EPA calculated that 33.7-kilowatt hour of electricity is equivalent to one gallon of gas.

we should go inside the Electric Vehicle reference block that is performance calculations: 

inside this block we will get actual mpg calculations:

Now here we have three different inputs that are taken into considerations:

1. Vehicle Speed

2. Fuel Flow

3. Battery Power

The Vehicle Speed inputs are in m/s which is converted into miles by multiplying with 0.000621371. Similarly, the kilogram of fuel is converted into cubic meters by multiplying by 1/(1000*0.739). This cubic meter value is then converted into gallons by multiplying it with 264.172, The mile value and gallon value are used to find mpg pf the vehicle.

Now the battery value is initially converted from watt to kWh by dividing with 1000 and then to gallon equivalent by again dividing it with 33.7 { Since 33.7 kWh = 1 gallon }, then divide the value by 3600 to get in per second and multiply by 0.0037854 in to get the value in cubic meter per gallons.

3>>Ans: HEV Reference Application with WOT drive cycle:

Use the command 'autoblkHevStart' in the command window to open the HEV reference application. Then double click Drive Cycle source block and then change the drive cycle to 'WOT' as shown in the below image. Also configure the parameters like time duration, WOT start time, initial speed, Final speed, Max Speed, and Time to stat deceleration.

Now change the wind speed and grade from Environmental block:

The following graphs are obtained for WOT analysis: 

Now from the above graphs, we can see that,

Trace velocity Target and Actual Graph: the yellow line indicates the desired path, and the blue line is the actual path. So it can be seen that battery power is not enough to meet the requirements of the grade and wind velocity.

Battery Current Graph:   When the vehicle is accelerating the battery current is also increasing. When the velocity is constant the current requirement also becomes constant. When the deceleration starts the battery current becomes negative indicating regenerative braking

Battery SOC:  The battery SOC keeps on decreasing until regenerative braking starts, then it increases the SOC of the Battery.

Engine, Motor, and Generator Speed: Initially only the motor is used to start the vehicle as the motor has high initial torque. Later when the generator i.e., the red graph kicks in charging the battery when SOC drops below 70%. Engine graph cannot be seen as it may have overlapped with the generator. 

Engine, Motor, and Generator Torque:  Motor Torque is initially high i.e., blue line and then the engine starts in at a later stage i.e., yellow line. Generator torque i.e., the red line is negative as it's charging the battery.

4>>Ans:  Now when we simulate  the EV with WOT drive cycles, wind velocity as 5 m/s, grade as 5 degrees, and keeping the rest parameters as same as the above HEV case:

 Now we get the following Performance graphs:

Now when we compare the graphs of both EV and HEV following conditions were seen that is as follows:

>> In the First graph { Target and Actual Velocity Graph } performance is almost the same, the reason could be that in that region only the motor was operating so the performance in both EV and HEV is similar.

>> The Battery Current is drawn by HEV initially is up to 500A and later decrease to 200A. This can be attributed to the fact that initially the only the motor takes all the load and later engine kicks in so motor load drops thus current drawn by the motor reduces and during the deceleration is seen that the negative current flows for a longer time in HEV as compared to EV. So we can say that regenerative braking is more aggressive in HEV.

>>SOC improvement of almost 15% is seen in HEV during deceleration and only 2% improvement can be seen in EV during deceleration. This can be understood for the same reason as explained above. 

>> Motor Torque and Motor Speed are stable in EV and they fluctuating a lot in HEV during the starting, also the peak RPM of the motion in EV is less than HEV. These differences can be attributed to the fact that the battery power of EV is more than HEV.

>> Fuel Economy of EV is greater than HEV, this is because Electric motor is more efficient than the engine.