Week-4 Challenge WOT Condition Part-2
1. What is the difference between mapped and dynamic model of engine, motor and generator? How can you change model type?
Powertrain provides two different types of engine models:
1. Mapped Models
2. Dynamic Models
EV Mapped Models: Run simulations with available data that is given in the lookup tables. Advantage of having this type of configuration is that we can give data that is as per our requirement and specifications. Mapped engine models are basically used in applications involving design that doesn’t require dynamics characteristics.
EV Dynamic Models: This type is defined as the actual model that represents actual components. Dynamic model consists of actual motor and motor controller along with interior permanent magnet controller. This is real time simulations and provides results based on real time scenarios. The time it takes to generate results is comparatively longer than mapped type. These are suitable for designing control that depends on dynamics characteristics and subsystem.
To change from one model type (Mapped) to another model type (Dynamic) follow below steps.
Firstly, right click on Mapped model and select Subsystem & Model reference, convert to and then select Variant Subsystem to activate Variant subsystem option.
Secondly right click Dynamic block and select Variant, further select open in Variant Manager.
Right click MotGenEvDynamic and select “Set as label mode active choice”
Now the desired block (Dynamic) will be activated.
2.How does the model calculate miles per gallon? Which factors are considered to model fuel flow?
Miles per Gallon is a criterion that relates distance traveled by a vehicle and the amount of fuel consumed.
Vehicle speed and battery power are two different factors that are considered to model fuel flow.
Vehicle speed is integrated first to determine the value of distance with respect to time. Then Unit conversion is done to get the desired output.
3.Run the HEV Reference Application with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.
With the help of document on Hybrid Electric Vehicle with WOT cycle from MathWorks we can use the command “autoblkHevStart” in command Window to activate the Simulink block diagram.
Case1: Without grade and wind velocity parameters.
From the options available in drive cycle block, we can select WOT since its our desired type of drive cycle.
Start time, Nominal reference speed, time to start deceleration and final reference time are given as per below image.
After running the simulation with WOT drive cycle, we can further visualize to understand the parameters such as battery SOC, Velocity and fuel economy as follows. This case is where we have no grade angle or wind velocity considered.
Observation: Trace velocity plot describes the desired velocity and actual velocity attained. Other plots provide various information on Battery SOC, Fuel economy, Battery current, engine speed and torque. The max value of battery SOC is determined from the plot as 80.
Case 2: Providing grade and wind velocity in the environment block
In the below case, by selecting the environment block we can give information on other forces such as climb angle and wind velocity acting on the vehicle.
By giving the grade angle = 7 and wind velocity = 20
We can visualize the performance to understand parameters such as maximum and minimum for trace velocity which will further provide details on the speed that can be attained with limited battery SOC and the desired speed for given case.
Observation: With climb angle and wind velocity, the speed value was found to be not sufficient enough considering the battery SOC.
4.Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains.
With the help of document on Electric Vehicle with WOT cycle from MathWorks we can use the command “autoblkEvStart” in command Window to activate the Simulink block diagram.
Case1: Without grade and wind velocity parameters.
From the options available in drive cycle block, we can select WOT since it’s our desired type of drive cycle. Start time, Nominal reference speed, time to start deceleration and final reference time are given as per below image.
After running the simulation with WOT drive cycle, we can further visualize to understand the parameters such as battery SOC, Velocity and fuel economy as follows. This case is where we have no grade angle or wind velocity considered.
Case 2: Providing grade and wind velocity in the environment block
In the below case, by selecting the environment block we can give information on other forces such as climb angle and wind velocity acting on the vehicle. By giving the grade angle = 7 and wind velocity = 20.
Comparison: Considering the pure electric and Hybrid electric vehicle with same load conditions, the fuel economy in Miles per Gallon can be used to determine the efficiency criteria. For pure electric vehicle, it is evident from the graph that the efficiency is greater than hybrid electric vehicle.