WOT Condition Part-2

Aim:

1. Find difference between mapped and dynamic model of engine, motor and generator.
2. To change model type
3. The model calculate miles per gallon. Find the factors which are considered to model fuel flow.
4. Run the HEV ReferenceApplication with WOT drive cycle. Change the grade and wind velocity in the environment block.
5. Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains

OBJECTIVES:

Using powertrain blockset which is a set of fully assembled reference applications, including gasoline (spark-ignition, SI), diesel (compression-ignition, CI), hybrid, and electric vehicle systems, as a starting point for our powertrain system model.

Initialy we study the mapped and dynamic model of engine, motor and generator. Then changing the grade and wind velocity of EV/HEV ReferenceApplication compair their results.To model a powertrain system for this project, we can select a reference application based on the powertrain type. Each reference application includes plant models, controllers, a longitudinal driver, and drive cycle data.

The component library in Powertrain Blockset provides blocks of physical systems and controllers for:

1. Propulsion
2. Transmission
3. Drivetrain
4. Energy storage
5. Longitudinal vehicle dynamics
6. Drive cycle data and longitudinal driver

• This is backword facing model as it moves from drive cycle to final car output.
• Longitudenal driver which is a simulated driving enviroment where all the velocity input will followed by vehicle. This will act in such a way that it can minimise the difference between the acutual and reference speed . It is itself a controller different controller i.e Perportional integrial controll
• In controller block has powertrain input (from vehicle plant and provided data), output (motor torque command as required traction and braking command) and powertrain control module (PCM).
• The PCM consist of mainly 2 blocks regn braking control and Motor torque arbitration and power management. In power management, if the electrical power is within the limits then the motor torque command will be used or if power exceeded then limited torque will be available with the motor.
• Apart from that it also has soc (battery management model), which tells about maximum charge and discharge rate of battery. For that a lookup table given to limiting that current which is basically Variation in soc w.t.h to limit?
• In the passenger car block has electrical plant and drivetrain. In the electrical plant we have battery and motor generator. In motor generator we use mapped condition instead of dynamic.
• In the drivetrain , the mechanical power flows from the motor shaft to wheel.
• Visualization block is used to plot the information coming from drive cycle and the final outcome will be plotted.

Difference between mapped and dynamic model of engine, motor and generator:

Mapped model of engine, motor and generator represent macro behavior as a set of lookup tables (motor speed, power, torque, brake torque, air mass flow, fuel flow, exhaust temperature, efficiency, and emissions). In these tables we already have assigned values as it has a real time block.

I.e. A mapped motor lookup table in this we can map the available motor data

Whereas the dynamic model is an actual model that shows the real components in witch is manually field and has sample rate less than 1 second. Power electronics simulations are mostly performed dynamically. It is used to perform subsystem transient simulation for more detailed experiment

i.e. In this we have actual PM controller and 3 phase voltage source inverter

The mapped model take less time then dynamic as it is less detailed and has a working range of 1 second.

To change a model type:

Follow the below steps-

After opening the powertrain block select the desired vehivle type and go to passanger car block>electric plant> MOTOR> right click> variants> slect the model.

Factors considered to model fuel flow:

To model a fuel flow the vehicle speed and battery power is considered.

The model calculation for miles per gallon:

Calculation of battery power and vehicle speed in miles per gallon is used to find , that how much economical the battery is as compare to engine fuel consumption. This mile per gallon is equitant to energy generated by electric power. This helps us to understand the economy of both vehicles.

The vehicle speed and battery power are input to compare the fuel economy of engine with battery, we simply convert the battery power to gallon and vehicle speed to miles using the following mathematical steps-

meter/second > product and `root` > meter > bypass to next block > Miles

battery power > divide by 1000> kw> divide by 33.7 > Gal/hr>`(m^3) / (Gallon)`

After that, the Miles and Gallon > product block > Miles/Gallon.

Electric vehicle reference model

Run the HEV ReferenceApplication with WOT drive cycle (Change the grade and wind velocity in the environment block):

Open the HEV reference application which shows the below screen-

configure a drive cycle first with WOT and give simulation time 50 sec at both the places all other are the default values.

Go to envirenment block and put the values of grade angle and wind 8 and 35 respectively

After that just run the simulation an get the following result -

The vehicle velocity is less than the reference velocity as the grade and wind velocity have their impact. The maximum velocity obtained is 50 mph.

In this period the engine/motor/generator speed is around 13000rpm which comes near to zero during regenerative braking. The maximum torque produced is 200 nm.

In initial 30 seconds the SOC declines its lowest up to 42% and the battery current is about 160A in this period.

The maximum fuel economy is about 6 mile per gallon at 32 secondes.

Keeping all other parameters same simulate the pure electric powertrains and compare the simulated results of hybrid and pure electric powertrains:

After selecting the EV reference application just run the simulation of pure electric powertrains (EV) we obtained the following result -

EV Results HEV Result

• From both the result curves, the maximum obtained vehicle speed in HEV() is higher than EV()
• The fuel economy difference can be clearly observed that EV (27MPGs) has very big advantage over HEV (7MPGs).
• The EV SOC is still 99.995 after 50 seconds whereas in HEV its is 42% from 60%, which is very high as compared to EV.
• Battery current is again higher in HEV (160A) then EV (40A).
• Torque and speed is also higher IN HEV then EV as shown in curves.

• Conclusion:

  The rate of battery discharge is clearly less in EV as compare to HEV.

  The EV has more efficiency then the HEV due to less power loss.

  The EV has no emission and fuel consumption.