Week-4 Challenge WOT Condition Part-2

Aim:

1.To understand mapped models and dynamic models.

2.To understand how the fuel efficiency is calculated in miles per gallon and the factors affecting the model fuel flow.

3.To study the effect of gradient and wind velocity on the simulation in HEV powertrain.

4.To compare the above simulation results with a EV powertrain

1)

Mapped model:

The mapped model refers to the block where the inputs and outputs of the block are given in steady state look up tables.The mapped model is used for simulation to study the effect of a factor on the simulation in the system level.

We can use the mapped engine model to study the effect of valve timing,quantity of fuel injected/sprayed, etc. on the engine output, it is similar to the moto and generator model.

Dynamic model:

Dynamic model refers to one which breaks down a system or sub-system into its components.The output of these components combined is taken as the output of the system.This type of model can be used when we need a more detailed model. To use this type of model, we need to have the component level data as we will need to give input to each of the componenets and take their output. This type of model is used to analyze the impact of individual components on the overall performance.

2)

For HEVs, the miles per gallon is calculated by combining the fule efficieny of the gasoline along with the electric power. It has been found that gallon of gasoline is equivalent to 33.7 kwh of electrical power.This value is tested and given by the united states environmental protection agency.

Ex:A battery propels the vehicle for 5kWh capacity of battery, the miles per gallon equivalent is given by

5miles/kWh*33.7 kWh/gallon=168.5 mpGe

The miles per gallon calculation is done by the performance calculatins block(sub-system)

For this, the vehicle speed , fuel volume flow and the battery power is required.The distance travelled is calculated by integrating the vehicle speed with respect to time. Then the value is converted from m to mile.Fuel volume flow is calculated by integrating it similarly with respect to time.Along with this, the battery power is converted to kW and then converted to kWh/US gallon by diving the obtained by 33.7.This value is then converted from m cube to US gallon.The two values are divided with each other and the miles per gallon value is obtained.The factor considered for modeling fuel flow are vehicle speed, fuel volume flow and battery power.

3.

Once the simulation is done, we will obtain the results in the form of plots. These plots can be obtained from the visualization block in the performance and FE scope.For the WOT condition, we can see the trace and actual velocity in the first plot. The blue line represents the velocity that we had defined. The orange line represents the actual velocity. We can see that there is significant difference between the two curves. As the time increases , the actual velocity gradually increases due to gradient and wind forces acting on the vehicle.Also in the decleration, we can see that the final velocity is 0 is obtained after the specified time which is 60 seconds. In terms of the Battery State of Charge, we can see that the SOC is cinstant at 80 for 1 second i.e before the start of the WOT condition. From the next second, the SOC has reduced steeply to below 60. After 60 seconds, ie after the decleration has started, we can see that the SOC increases again. For the motor speed, it is increasing from the beginning and after 30 seconds, it almost becomes constant at 5800 rpm.As the deceleration starts, the motor speed reduces to almost zero. The generator speeds is zero till the 17 or 18^th second and after the value increases. As the deceleration starts, the speed of the generator also decreases from around 5800 rpm to around 4200 rpm.As for the fuel economy, there is an increase in the fuel economy till the deceleration is about to start. After 1 or 2 seconds have passed after the deceleration has started, the fuel economy also starts to decrease. The battery current increases from zero to around 450 A and is almost same till 17 and 18^th seconds.Then there is a dip to around 190 A and then till the deceleration starts, the value is same.After the deceleration has started, the current goes down below zero and then it becomes constant.

4.

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

Pure EV can achieve less velocity than that of HEV.HEV can attend velocity above 60 mph but in pure EV velocity is less than 60 mph.Motor speed in rpm is also less than that of HEV.But path tracing is the same as that of HEV.But motor torque of pure EV is almost the same as that of HEV.Battery current uses is almost half in pure EV to produce power as that of HEV.Also as battery use is less, battery draining is low & it can be seen from the SOC graph.From the SOC graph, it can be seen that for the same parameters battery uses is 5 times more in the case of HEV than that of pure EV, battery drains fast in the case of HEV.Fuel economy is also almost double in the case of pure EV than that of HEV.

Result:

Thus the answers for the question is been given.