Simulation of WOT Condition

TARGET>

1. What is the difference between mapped and dynamic model of engine, motor and generator? How can you change model type?
2. How does the model calculate miles per gallon? Which factors are considered to model fuel flow?
3. Run the HEV ReferenceApplication with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.
4. Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains.

SOLUTION>

1.

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Mapped Engine Model	Dynamic Engine Model
i) Mapped Engine model runs in high level based on the motor data given to look up table.	i) Dynamic Engine model runs based the actual component data.
ii) It takes torque torque, fuel consumption, mass air flow, exaust gas temperature, efficiency and emmision into account depending on the load and measured engine speed.	ii) It takes Engine dynamics, primarily intake airflow and turbocharger in account of calculating.
iii) It works faster than the Dynamic Engine model.	iii) It works slower than the Mapped Engine Model.

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Motor	Generator
i) Motor converts electrical energy into mechanical energy	i) Generator converts mechanical energy into electrical energy.
ii) When motor works toque and speed both remains in the same direction or positive.	ii) When generator works torque and speed remains in opposite direction or one of them is negative.

>> We can change the model type by simply switching the model type and activating the other model based on application. Dynamic Engine model is suitable for the design of control algorithms, evaluation and diagonosis. Whereas mapped model is suitable for analysis and design that does not require dynamic characteristics.

2.

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To calculate miles per gallon - i) Vehicle speed--Avg Distance is calculated from vehicle speed by root mean square and integrating in a span of time in unit meter. Then distance is devided by 1000 to get speed in km and by 100 to get per 100km distance.( Block 2 ) ii) Fuel flow- First integrating the fuel flow for a span of time then deviding it to get fuel volume from m^3 to L.( Block 3) iii) Battery power- Battery power is converted into kw from w simply deviding by 1000. Then as 1 us gallon of fuel contain 33.7 kwh so further to convert it into kw deviding by 3600 is done. Finally to convert it into m^3/gallon 0.00378541 is multiplied with it.( Block 4) To get distance in miles further gain of 0.000621371 and volume in gallon gain of 264.172 is calculated. ( Block 1)

>> Three factors are cosidered to model fuel flow economy, which are Vehicle speed, Fuel flow rate and Battery power.

It takes the speed from the drive cycle, battery power from battery SOC and fuel flow from engine output to calculate efficiency.

3. >>

HEV REference Application with WOT drive Cycle , where parameters are ---

WOT response is---

Where,

After changing the grade and wind velocityin the environmental block---

Now WOT response is---

Where,

We can compare the graphs between changed(A) and unchanged(B) environvental condition and observe that- i) For case B dynamic velocity reaches the nominal speed at nearly 25 sec but in case A dynamic velocity does not reaches nominal speed during the drive cycle. ii) For case B Battery SOC decreases 60% to 46% in 55 sec of time interval where as in case A Battery SOC decreases 60% to 22.5% in 55 sec. iii) For case B Fuel economy MPGe drops 8.997 in 55 sec and in case A it drops 18.19 in 55 sec. iv) For case B Battery current decreases 130.653 Amp in 55 sec but in case of A it decreases 3.106 Amp in 55 sec.

4. >> Keeping same drive cycle for pure EV ie. WOT with same parameters as HEV---

Keeping the grade and wind velocity same as HEV---

Now WOT response is---

Where,

Comparing the graph of EV and HEV for same parameter we get that - i)To reach the same desired speed EV take more time than HEV. ii)For the same time interval of 55 sec EV decrease 100% to 97.5% and HEV decreases 60% to 22.5 % of Battery SOC. iii) Fuel economy in case of EV is much better than HEV. in case of EV fuel economy for 55 sec is 26.51 and in HEV is 8.997 for the same time interval. iv) For EV Battery current drops 308.584 Amp and in HEV 130.653 Amp for the same interval of time ie. 55 sec.