Week-4 Challenge WOT Condition Part-2

Agenda:

The challenge explains the use of powertrain blockset for analysing the Hybrid and EV. The quieries set starts with difference between mapped and dynamic models of engine, motor and generator. The HEV is anlysed using miles/gallon, grade and wind velocity and compared with pure EVs.

Now start with the first challenge

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

Mapped Model:

i)Mapped models are formulated with the past results or expermimental analysis or mathematical relations. 

eg: The current flowing through the resistance is calculated by using the ohms law. In simulation, the current is calculted by using the mathematical relation between voltage and current through resistance.

ii) The another way to formulate the mapped models are using look up tables which has the experimental analysis of that element. if the module has more than one input and output, then this type of formulation is more useful. The advantage of this formulation is that it almost resembles the practical difficulties of the element or module.

Example: Modleing of battery with eletric equivalent circuit model.

iii) In the present challenge, mapped model of engine is formulated with the  lookup tables. The lookup table values are added with the expertise knowledge or experimental analysis. 

Mapped engine:

In the above example, mapped core engine is shown which needs the two inputs and many outputs.

Mapped motor, ehich has the inputs of battvoltage and torque command and 4 outputs.

Dynamic model:

The model which behaves with real time or practical inputs can called as Dynamic model. The Dynamic model receives the input commands from the sensors which senses the physical signal and feed to the dynamic models for acting to the model behaviour. This model exacts behaves as a original system/module and easily to estimate the performance of the module before going to production.

The above figures are dynamic models for CI engine and SI engine.

The dynamic model of the Indiction motor is shown in the above figure which recieves load torque and phase voltage as inputs. The motor is operating according to the load torque and phase voltage. 

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

The model which calculate miles per gallon is shown as follows

The internal diagram of MPG is shown as follows

The factors that are used to MPG are vehicle speed, fuelvolume flow, and Battery power.

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

The block diagram is as follows

The grade and velocity of the vehicle system is edit ar environment. 

wind velocity is given 25 m/sec

grade is given 5deg

The results are shown in the figure

In the first graph, the vehicle velocity is not follow the throttle input. The SoC is reduced from 80 percent to 70 percent at the throttle input and maintain 70 percent when throttle input is with drawn. The engine speed and engine torquue are affected which is shown in the fig 2 and fig3. The Battery current  of 500A is drawn but due to sudden change in input, the current has transients at on and off of throttle. 

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

Results of hybrid electric powertrain

The results of the EV power train is shown in the above fig. 

1. Graph-1

The vehicle is tested with FTP75. The vehicle velocity is reached with drive cycle velocity because of grade is zero and wind velocity is zero. In both HEV and pure EV are follows acts similarly at vehicle velocity.

2. Graph-2:

In HEV, engine speed, motor speed and generator speed is analysed according to the drive cycle velocity. where as in pure EV is analysed with only motor speed. 

3. Graph-3:

In HEV, engine torque, motor torque and generator torque are analysed according to drive cycle where as in case of pure EV is analysed with only motor torque.

4. Graph-4:

The battery SOC starts with 60% soc in case of HEV and 80% SoC in case of Pure EV. In case of Pure EV some parts of the soc is raised during decelaration and decreases lineraly with constant average current and maintian constant at velocity is zero.

5. Graph-5:

Battery current, is negative which means the battery is charging and and discharged more at maximum speed period. In both vehicles the battery behaves similarly at accelearation and decelaration.