Project 2
Aim:- Modeling of development of a forward energy-based fuel consumption model of a P1 hybrid vehicle
Objectives:-
1] Tabulate the fuel economy numbers (kmpl) for UDDS and HWFET cycle. Compare these numbers with the baseline numbers for conventional vehicle.
2] Plot the time trace for engine, transmission input, transmission output and wheel speed on one plot.
3] Plot engine torque, engine power, fuel rate and fuel consumption using subplots.
4] Plot accelerator and brake pedal, gear command, vehicle desired and actual speed, vehicle distance using subplots.
5] Plot the engine operating points on the engine fuel map.
6] Plot motor speed, torque, motor input power using subplots.
7] Plot pack voltage, current and SoC using subplots.
8] Plot the motor operating points on the motor input power map, with the motor max motoring and generating torque curves.
9] Generate the plots for UDDS and HWGET drive cycles.
In this model We use Forward Model:-
It also known as dynamic simulation. Dynamic models are used for detailed simulations. In this model force/torque/power is the input and the vehicle state variable velocity and acceleration are outputs. The models and simulatios are more realistic due to phhysical casualty hence appropriate for control development. There is feedback loop to meet the desired vehicle state. It is mainly used to simulate a vehicle on a driving cycle to analyse the dynamic behaviour of the system helps significantly in control development.
Process:-
- Load the Project2 folder as the Current Folder in Matlab.
- Run the “Project2_InitFile.m” Matlab script.
- The Drive cycle selection is done here.
In this we created four conditions as stop, start, drive and regenration braking. The initial block represent the stop condition. In which the engine is off. The engine and motor throttle conditions are zero. Then the second block represent start condition. In which the mode is 1 the electric motor throttle is only used to provide the required torque and power to the vehicle. the engine is off and engine throttle conditionis zero.
The state 1 and state 2 are connected using the links i.e. it moves from state 1 to state 2 when acceleration is less than one or SOC is less then the minimum SOC.
State 3 Represtents mode 2 ii.e. engine is on and the engine throttle is also having positive value from the driver but the electric motor throttle is zero. It changes form state 2 to state 3 when engine speed is graeter than or equal to engine idle speed.
state 4 represents regenrative braking which is model 3 In this state the engine is on but the engine throttle is having no input from driver whereas the electric moto receives the negative power due to braking.
The inputs are given to chart is Acceleration, barke, engine speed, vehicle speed, SOC, and clutch lockup.
The output we get from the chart is mode, engine condition, engine throttle condition, and electric motor throttle condition.
Modification done in all Unit modeling. they showed in next figures.
Engine Control Unit:
In this control model We use engine control unit in that give input Engine speed through creating look up table. in that table we give input Maximum torque and map speed then also create 2nd look up trable in that give input ct torque and map speed then it substracts and multiplied. the engine speed also give to ideal contro speed to integrate from this we meet output of engine required torque.
Transmission Control Unit:
In this unit we create steadfy flow variable state for controlling of gears of vehicle as in ascending and descending order with respect to time, speed, distance. and give input to this steady state is vehicle speed in m/s to mph.
Shift Logic Unit:
Brake Control Unit:
In this calculate brake torque and then all three control signals output is give to powertrain.
Electric Motor Control Unit:
Engine Control Unit:
In this model we used map based model to model the fuel consumption of engine. It is based on maximum Torque and minimum torque from the controller. and then it saturated torque and give output then saturated torque and speed map give fuel consumption takes the speed and torque then the output goes into saturated then its integrated.
Power train > Transmission > Torque converter
In these model we take engine torque, gear selector from controllerb for transmission of gear ratio. The ratio is multiply by transmission input torque and then the transmission efficiency positive torque and negative torque gives transmission input speed. In this case torque converter connects the engine to transmission it is part of transmission. In it basically engine dynamics and that is decoupled.
Differential:
In this taking input is the transmission output then its going to the differential ratio multiplied the output and input torque then meet axle torque. The axle torque is a lower than the transmission torque and differential ratio.
Wheel:
In this model we take the axle torque from differentail and brake torque from controller. it is substracts and multiplied rolling radius and velocity then we meet the tractive force from axle and brake torque. and the wheelspeed is meet using velocity.
Vehicle Dynamics:
In this takes tractive force and road load. It is dictates vehicle speed based on tractive force and road load.
Battery Modeling:
- Estimated Storage System (ESS)
In this we give input as power then it multiply and give to pack current. then from soc estimation meet output SOC its give to terminal voltage as input and then meet terminal voltage as output.
- Terminal Voltage
In this use input SOC it is connected to 1d lookup table 1st table variable interpolated as state of charge and open voltage circuit. In 2nd table variable interpolated as resistance discharge and state of charge and in 3rd table variable interpolated as resistance charge and state of charge. Then it is passed to switch block for controlling the threeshold. then they give voltage limits as max volts and min volts. then meet terminal Voltage.
- SOC Estimation (Pack Current)
In this we integrate pack current and convert it rad to amp then saturated and meet SOC.
Then we create one coding file for creating plots and to meet all answers. that file shown in next.
Fuel Economy Numbers for project 2
| S.No | Drive cycle | Fuel Economy Number (KMpl) |
| 1 | UDDS | 18.658732735951310 |
| 2 | HWFET | 22.079890761637770 |
As we see the fuel economy is high in HWFET compared to UDDS. It is because in urban driving the vehicle encounters more traffic and it has to stop for fever distance and it consumes more fuel at the starting. In HWFET the vehicle encounters no traffic and it moves without use of too much braking so it will have more fuel economy number.
Plotting the time trace for engine, transmission input, transmission output and wheel speed on one plot
For UDDS Drive cycle:
For HWFET Drive cycle:
In this we can see the graph is more fluctuate into UDDS drive cycle compared to HWFET drive cycle. It is because UDDS has more starts and stops and in HWFET less starts and stops.
Braking is high in UDDS compared to HWFET.
Peaked engine power reached nearly 4200 RPM in UDDS drive cycle and in HWFET cycle it reached at 3000 RPM.
Plotting engine torque, engine power, fuel rate and fuel consumption using subplots
For UDDS Drive cycle:
For HWFET Drive cycle:
Vehicle cosumed more power in UDDS drive ccycle bacause in urban area the vehicle require many starts and stops so it required more power compred to HWFET.
Engine is high in UDDS drive cycle compred to HWFET drive cycle because the starting from rest the vehicle requires more torque to overcome the static friction.
The fuel rate is high in HWFET drive cycle compared to UDDS drive cycle because it will be in continues movement so it consumes more fuel.
The fuel economy is high in HWFET because In UDDS cycle many starts and stops so more fuel cosumes and the engine is in idle postion.
Plotting accelerator and brake pedal, gear command, vehicle desired and actual speed, vehicle distance using subplots
For UDDS Drive cycle:
For HWFET Drive cycle:
In UDDS The acceleratior and brake pedal have more fluctuations because of frequent starts and stops. but in HWFET the brake pedal fluctuations are almost near to t he zero line as there will be no frequent stops.
In UDDS cycle mostly runs on 1st and 2nd gears and the 3rd and 4th gears are rarely useas it does not achieve high speed inn that traffic. In The HWFET cycle the vehicle mostly runn in 3rd and 4th gears as it will moving at high speeds.
Plotting the engine operating points on the engine fuel map
For UDDS Drive cycle:
For HWFET Drive cycle:
Plotting motor speed, torque, motor input power using subplots
For UDDS Drive cycle:
For HWFET Drive cycle:
The fluctuations will be more in UDDS cycle compared to HWFET cycle because UDDS has many starts and stops due to traffic as the purpose of motor in P! hybrid is initiation of crank rotation and they are more in UDDS cycle when compared to HWFET cycle.
If the purpose of the motor is to provide traction then both the cycles wouldb have more flyctuations.
We can observe that the motor power and torque are very high in HWFET at the start and they are almost zero after few seconds but in UDDS it has continuod fluctuations this is because of frequent braking in UDDS.
Plot pack voltage, current and SoC using subplots
For UDDS Drive cycle:
For HWFET Drive cycle:
The pack voltage and current will have more fluctuations in UDDS as compared to HWFET cycle because of the frequent start and stops throughout the drive and the battery has to provide the energgy everytime when the car is starting from the idle position.
SOC decreased in the UDDS cycle wrt time but it has increased in HWFET cycle. It is because in UDDS we have frequent start and stops and battery has to provide the energy has evertytime when the caris starting from the idle position and the SOC decreases but in HWFET cycle The Vehicle will be moving continuously without braking frequently and the alternator is utilised to transfer some engine power to the battery through motor so SOC increase in the HWFET cycle.
Plotting the motor operating points on the motor input power map, with the motor max motoring and generating torque curves
For UDDS Drive cycle:
For HWFET Drive cycle:
For USSD Drive cycle:
For HWFET Drive cycle:
Conclusion:-
The various performance of characteristics and operating points of UDDS drive cycle and HWFET drive cycle are analysed and the graphs are plotted
- Time trace for engine, Transmission input, Transmission output and wheelspeed with respect to time.
- Engine torque, Engine power, Fuel rate and Fuel consumption with respect to time.
- Accelerator and brake pedal, gear command and vehicle desired, actual speed, vehicle distance with respect to time.
- Engine operating points on the engine fuel map with respect to time.
- Motor speed, Torque, Motor input power with respect to time.
- Pack voltage, Current and State of charging with respect to time.
- The motor operating points on the motor input power map with respect to time and also it comparing with HWFET drive cycle and their numbers also compared.