Week-4 Challenge WOT Condition Part-2

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

Mapped model –

These types of model uses lookup tables to characterize performance of a system. Look up table contains typical values of a variable with respect to another variable. In case of mapped engine, look up tables contains actual torque, fuel flow rate, Break specific fuel consumption and engine emissions to characterize engine performance.

These model used we don’t have component level data and we have data from dynamometer or GT-POWER tool.

Mapped model of CI engine -

Mapped model of Motor -

motor takes required values of variables like- torque vector, speed vector, from lookup table.

Mapped model of Generator -

Dynamic Model –

These types of model is an integration of lower level components, by combining components int his way capture the dynamic effects. SI engine model has intake manifold, air intake system, exhaust manifold etc. blocks or we say lower level components, these all are integrated to get engine performance.

These model used when we have component level data and these are useful to find impact of individual component on overall performance.

Dynamic model of SI engine -

Dynamic model of Motor -

it has interior PM controller, 3-phase inverter, component blocks to perform.

Dynamic model of Generator -

We can change model in variant manager by activating desired model or we can change variant in menu which we will get by right clicking.

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

Fuel economy is calculated with vehicle speed and battery power, by converting them into suitable units.

Start with values of power supplied by battery. first Divide it by 1000 to convert it into KW and then divide it again by 33.7 which is equivalent to US gallon, then again divide it with 3600 to convert it into US gallon per hour and convert it into m^3 by multiplying 0.00378541.

Now take values of vehicle speed and integrate it which will give distance values. Now convert these into miles and divide it by 264.172 to get values in miles per gallon.

Factor to be considered during model fuel flow – Battery power, vehicle speed, Fuel flow (for HEV).

Study 3 -Run the HEV ReferenceApplication with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.

We run the HEV (multi mode) reference application after giving grade value 15 and wind velocity 8 in the environment block. We took WOT drive cycle with simulation time and reference speed 30.

Result –

We got a scope contains six plots, represents variation in performance parameter with time.

1. We can see in trace velocity plot, vehicle is failed to attend maximum velocity (67mph) as per driving cycle. Wind velocity and grade effected vehicle velocity that’s why vehicle got maximum velocity 10.5mph only.
2. Battery provides around 500 amperes during peak demand which is between 10 to 20sec. after it ampere is negative means current direction is towards battery.
3. Motor is running at around 8700 rpm in peak demand and engine and generator has negligible speed. At the time of deceleration maximum speed of engine is around 3739 rpm. Generator traces similar speed at deacceleration.
4. Initially soc is 80%, but it rapidly falls in acceleration condition to 70%. After 20sec it is charged by generator and it attains 80% soc after 75sec.
5. Motor torque is around 300Nm in peak demand and engine and generator generators similar torque values in deacceleration condition but in opposite direction.
6. Peak fuel economy is 1.3 miles per gallon in acceleration state but it fall rapidly in deacceleration state because there is need of fuel in deacceleration of vehicle.

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

Plots obtained

HEV multi mode model-

EV model -

Comparison of Results –

1. EV failed to achieve maximum speed due to wind velocity and grade effect.it got 9mph which is lesser than HEV (multi mode).
2. Motor achieved 3880rpm in acceleration condition, which is less than half of speed achieved by motor in HEV simulation.
3. Motor’s SOC decreased rapidly from 80% to 78.6% and here motor drew around 216 ampere current.
4. Motor provided maximum torque 280Nm at 6sec and after it became constant. HEV model provides higher torque if we compare it to EV model.