Week-4 Challenge WOT Condition Part-2

Difference between mapped and dynamic models of engine, motor and generator

Mapped motor: known as static motor when the model runs on lookup tables and predefined values. This model is faster than the dynamic model.

Dynamic motor: this model represents the real time working of the model. It takes real time input and gives output continuously. Simulation is slow compared to mapped model.

Mapped generator: this is similar to mapped motor, where the input values for generator block are predefined. Simulation time is also less.

Dynamic generator: this model represents actual generator which work in real time. Takes input in real time and gives output continuously.

Mapped engine: it is a steady state model where all input parameter like air mass flow, fuel flow, exhaust temperature, efficiency and emission performance are taken from lookup tables where values are predefined.

Dynamic engine: this model also represents the actual working of engine in real time.

To change the model from dynamic to static

1. In reference application model where ever the mapped model is used, below that a dynamic model is also present and its connected out since the connections are given to mapped models.
2. To use dynamic model, first we have to comment out mapped model and connect all the inputs to the dynamic model
3. Similar way is used to change from dynamic to mapped model.

CALCULATING MILES PER GALLON

1. Usually to calculate miles per gallon, the automobile is first filled with fuel fully until fuel tank is full.
2. Now again the distance travelled Is noted down and the difference between both the readings of distance travelled is found out. The difference value is divided by total fuel tank capacity. The value obtained is the average mileage of the automobile.
3. If the reading is 2000 miles and fuel capacity is 10 gallons after filling fuel completely. At the end of the trip the reading on odometer is 3000 miles

Difference in distance = 3000-2000 = 1000 miles

Fuel tank capacity = 10 gallons

Mileage = 1000/10 = 10mpg

4. In Simulink model, it calculates the performance in similar manner

5.The above figure shows how the model calculates mpg. Above model can be found in ‘visualisation block’ of HEV

6.In the above model we can observe that factors that are needed as inputs to model are vehicle speed, fuel volume flow and battery power

7.Battery power is converted into volume by multiplying and dividing by const conversion values, then the battery and fuel volume flow are added and integrated to get total volume of fuel consumed

8.The distance and volume of fuel is divide to get performance results in mpg and litres/100km.

9.Distance and volume of fuel is divided to get performance results in mpg and litres/100km.

TO RUN HEV REFERENCE MODEL IN WOT DRIVE CYCLE

1. TO change the drive cycle, click on the ‘Drive cycle source’ block and from the drop down, select WOT option
2. Now run the model to observe the results

3. We will the above results once the simulation has ended. In the first graph we can see the difference between drive cycle and actual velocity change. To attain maximum speed, it takes nearly 18 seconds and to reach zero velocity from maximum velocity it takes nearly 5 seconds. So, to reach top speed and again come back to rest it takes total of 23 seconds. So, the actual time varies from the drive cycle time.

   4. In the second graph we can observe that while achieving the top speed, the speed of motor is varying continuously and once achieved the speed of motor is constant and then the speed reduced continuously to zero. High speed of motor is observed when the vehicle is reaching maximum speed.
   5. In the third graph we can observe that the motor is giving high torque to achieve the top speed and then slowly is its reducing. Once it reaches the top speed then the motor torque slowly reduces and reaches zero. From here it goes negative because the motor is rotating due to vehicle speed thus the torque produced is due to vehicle, not due to motor so, its negative.
   6. In the fourth graph we can see that the current consumed by motor is high when vehicle is achieving top speed and is constant until the speed is maximum and then as the vehicle speed decreases the current also decreases and a point it goes to negative which means that it charged due to regenerative braking and then again becomes zero.
   7. In the fifth and sixth graph we can observe that the state of charge (SOC) has decreased as to achieve top speed some battery charge is used. And for fuel economy graph we can see economy is less initially as more fuel is needed to achieve top speed and then slowly it increases as the need of fuel decreases.

TO COMPARE THE RESULTS OF HYBRID AND PURE ELECTRIC VEHICLE:

1. By clicking the above link of EV reference model following model will open which will similar to that of HEV reference model, nut inside EV model there will no Engine model or block. The drive cycle is changed like the previous model to WOT drive cycle.

2. Now we run the model, we get results

3. Here in the above figure in the first graph we can see the top speed is achieved nearly at 14 seconds which very quick than the HEV model graph the time taken to come to zero velocity from top speed is nearly 5 seconds. So totally its takes 19 seconds to achieve top speed and come back to rest, which is quick than the HEV model.
4. In the second graph, we can observe that the graph is much smother than the HEV model. Thus, in electric vehicle the motor speed is smoother than the HEV motor speed.
5. In the third graph, here also the torque od motor is much smoother than HEV model an we can also observe that while the vehicle is decelerating, it is in regenerative braking mode, that's why the torque is negative while deceleration.
6. In the fourth graph, the SOC of battery is decreases slowly like HEV model but here it decreases much more than the HEV model. Since in electric vehicle only battery is used so battery is consumed more thus while achieving top speed the SOC line in the graph falls down more than that of HEV model graph. Since regenerative braking is happening, which charges the battery so the curve has raised little bit at the end.
7. In the fifth graph, we can observe that the current consumed the EV is less than that of HEV as the mass of EV is less so less current to used compared to HEV. Here due to regenerative braking, more current is produced than that of HEV to charge the battery.
8. In the sixth graph, we can see that the fuel economy the vehicle is very high than that of HEV. Thus, concluding that EV is now fuel efficient than HEV.