Week-4 Challenge WOT Condition Part-2
1.
Mapped model of motor or Generator
In the mapped model the data points are pre-assigned in the lookup tables.
The torque required is sensed and the motor or engine generates the required torque output simply without considering the real time motor or engine parameters.
The output values are stored for the given inputs correspondingly
The accuracy of the process is not high but the time required for simulation will be less and also by considering the real time parameters.
Dynamic Model
It uses the combinationof all the outputs of the subsystems to generate the output.
It runs by real time simulations as the required input from the drive cycle is taken for that individual real time simulation gets performed and summing all the subsystems gives the output for the simulations
To get the drive cycle we need to also note the initial bus voltage and current along with the vehicle feedback to calculate the actual simulation at the required point of the drive cycle
Also the accuracy of this method is good and the real outputs from all the subsystems to generate the output
But the simulation take svery long time to generate because of many individual simulations calculation of the motor or generator
Steps to select the model type
In the powertrian blockset module first we need to select the vehicle type as fully electric or hybrid vehicle
After that the simulink model appears by showing the work flow blocks of the model
In the blockset we need to go to passenger block electric plant
after this right click ang go to variance label mode active choice motor gen EV mapped or dynamic
2.
We calculate Miles per Gallon by how far a car can travel by the use of a gallon of petrol or Diesel for a Engine powered car.
• In case of an electric vehicle it tells us the energy which is equivalent to that of an engine powered car to propel the car through the similar distance
• Then by calculating amount of Fuel Energy required to move a engine powered car through a distance and then we compare the amount of electric energy that is required to move the car throgh the same distance and expresse that as the miles per gallon
The powertrain blockset has a model that calculates the miles per gallon for all kinds of vehicle.
The model will calcuate the Miles per Gallon by considering Fuel Flow and vehicle speed to calculate Fuel Consumption and Battery Power to calculate Battery Consumption.
To calculate Miles per Gallon we need;
• The inputs vehicle speed and the distance travelled are considered and then it is converted to the miles
by multiplying it with 0.000621371.
• Then the inputs from fuel flow Battery energy or Fuel energy are taken in mA3 and is converted into equivalent US Gallons by multiplying with
264.172.
• Finally the two inputs are calculated and equivalent US Gallon is further divided and the result is obtained in Miles per Gallon
Factors considered to model fuel flow:
Battery power:
• The amount of Energy from battery power required to move the vehicle Equivalent to that of the Engine is calculated here.
• The battery power is measured in Kw
• Then we convert the battery power into energy by multiplying it with the time into KWh.
• Then we convert the Energy from kWh to equivalent energy in US gallon of automotive gasoline by dividing with 33.7. since we get the energy in US Gallons equal in KWh we are trying to get the energy of equivalent LIS Gallons per seconds and we do this by dividing with 3600 and we convert the hour to seconds.
Then multiplying with 0.00378541 we convert the US Gallons per sec to the volume of the fuel flow in (mA3/ s) and then we multiply with 739 (California Phase Il Gasoline density) (i.) mA3/s * kg/mA3 which gives the result as mass flow rate kg's.
• Then finally the Battery energy equivalent in kg/s is given as a input for the fuel flow parameter in order to find the equivalent US Gallons enegy and estimate the Miles per Gallons.
Vehicle Speed:
• Vehicle speed is an important factor to determine the fuel consumption throughout the drive cycle.
• To convert speed to Distance we can Integrate with time and we are doing the same of converting the velocity to get distance covered byintegrating.
Fuel flow:
• The Fuel flow is the mass flow rate, the amount of fuel at each moment in Kg/Sec. By integrating this, we will get the result of mass of the fuel and by using this we convert it to the volume and by multiplying that by 1000 we can convert that into Litres.
• By comparing the two results we can get the amount of litre consumed to Run for 100km.
- The HEV combines conventional Internal combustion engine system (ICE), with an electric propulsion system
- The presence of the electric powertrain intends to achieve either better fuel economy than a conventional vehicle or better performance.
- For example the BMW 7 series is a full hybrid electric vehicle
- In the powertrain blockset we have selected the hybrid electric vehicle and this is the simulink model
- Here we can select the input parameters as we wish and we can Run the simulation to check the results.
Hybrid Electric Vehicle:
• A hybrid electric vehicle is that which combines conventional Internal combustion engine (ICE) system with an electric propulsion system
The presence of the electric powertrain is intended to achieve either better fuel economy than a conventional vehicle or better performance.
• Example of HEV is Toyota Prius.
Pure Electric Vehicle:
•Pure EV is that which exclusively uses chemical energy stored in rechargable battery packs with no secondary source of propulsion (e.g. hydrogen fuel cell, internal combustion engine, etc.) of energy.
• BEVs use electric motors and motor controllers instead of an conventional Internal combustion engines for propulsion. They derive all the power from battery packs. So they don't produce any emission of waste gas and they are eco friendly.
• They do have their own limitations such as range etc.
• Example of Pure EV is Nissan Leaf.
• Comparing both the HEV and PEV in the simulation
Case 1:
Simulation Condition:
The simulation is done for pure electric & Hybrid electric vehicle with Wide open Throttle (WOT) Drive cycle.
The Total cycle time = 100 seconds
The Top speed of this cycle = 80 mph
Time to start deceleration = 50 seconds
The Grade angle = 0 Degrees
The wind velocity = 0 m/s.
plot 1:
Shows the velocity of the vehicle with respect to the Drive cycle data with the Time scale on the x axis.
The top speed of 80 mph cannot be achieved as we have some additional forces acting and so the car can only run upto 108.9mph
The acceleration time to reach top speed of 108.9 mph = 50.2 seconds
The deceleration time from 80 to minimum = 9.8 seconds
plot 2:
Shows the changes in speed of the Motor in Rpm throughout the drive cycle.
Peak Motor speed = 1123 Rpm
plot 3:
Shows the Torque characteristics and its changes of Motor in (Nm) throughout the drive cycle.
Peak Motor torque = 260 Nm
plot 4:
Shows the Battery Current values (A) and its changes for various acceleration inputs as per the Drive cycle.
The peak current discharge from the battery = 216.8 A
The peak current charging to the battery = -173.7 A
Plot 5:
Shows the Battery state of charge SOC (%) and its changes corresponding to the driving inputs.
The state of charge decreased from 80% to 75.5% of charge in a time period of 50.3 seconds, for the specified driving conditions.
Plot 6:
Shows the Equivalent Fuel Economy as Mile per Gallons for the corresponding input driving conditions. But there is no fuel in pure electric vehicle.
However this gives equivalent battery energy required that of the fuel energy,and calculates the Fuel efficiency,.The maximum miles that the car can run per gallon of fuel equivalent = 20.45 Miles, for the given vehicle at the specified driving conditions.
Case2
Simulation Condition:
The simulation is done for pure electric & Hybrid electric vehicle with Wide open Throttle (WOT) Drive cycle.
The Total cycle time = 100 seconds
The Top speed of this cycle = 80 mph
Time to start deceleration = 50 seconds
The Grade angle = 8 Degrees
The wind velocity = 10 m/s.
plot 1:
Shows the velocity of the vehicle with respect to the Drive cycle data with the Time scale on the x axis.
The top speed of 80 mph cannot be achieved as we have some additional forces acting and so the car can only run upto 58.9mph
The acceleration time to reach top speed of 58.9 mph = 48.8 seconds
The deceleration time from 80 to minimum = 4.63 seconds
plot 2:
Shows the changes in speed of the Motor in Rpm throughout the drive cycle.
Peak Motor speed = 6254 Rpm
plot 3:
Shows the Torque characteristics and its changes of Motor in (Nm) throughout the drive cycle.
Peak Motor torque = 280 Nm
plot 4:
Shows the Battery Current values (A) and its changes for various acceleration inputs as per the Drive cycle.
The peak current discharge from the battery
= 225.8 A
The peak current charging to the battery = -163.7 A
Plot 5:
Shows the Battery state of charge SOC (%) and its changes corresponding to the driving inputs.
The state of charge decreased from 80% to 75.5% of charge in a time period of 49 seconds, for the specified driving conditions.
Plot 6:
Shows the Equivalent Fuel Economy as Mile per Gallons for the corresponding input driving conditions.However there is no fuel in pure electric vehicle so this gives equivalent battery energy required to that of the fuel energy, and calculates the Fuel efficiency.
The maximum miles that the car can run per gallon of fuel equivalent = 21.45 Miles, for the given vehicle at the specified driving conditions.
Observation(PEV VS HEV With Same Load Conditions):
1. The electric vehicle when compared with hybrid electric vehicle with the same environmental and Drive cycle conditions results in less top speed achievement The electric vehicle produces more values of Motor speed and motor torque compared to the hybrid vehicle's motor alone,but hybrid vehicle when it combines the torque of both motor and its engine it is higher than the electric vehicle's torque. This is responsible
to pull the Hybrid car at higher top speed compared to the pure electric.
2. As the pure electric car here uses Lithium-ion battery compared to the Nickel metal hydride battery the discharging capacity and the rate of charging is higher in the pure electric car. As it is able to discharge in a fast rate the motor can produce high amount of torque instantly compared to the hybrid vehicle. Also the state of charge shows the battery efficiency of the pure electric to be higher than the hybrid vehicle and this is also due to the battery type used in these cars.
3. The efficiency of the Electric car is higher than the hybrid car which is evident from the miles per gallon numbers of both of these cars.
4. Electric vehicle produces zero emissions whereas the hybrid one's produce waste gas emission.These are some of the observations from the
comparison of the above simulations using Powertrain Blockset.