Project 2

Aim :- To understand the functionality of a P1 hybrid and be able to model it , writing scripts in Matlab, modeling in Simulink, analyzing data and generating plots.

Task :-The task of this project is to quantify the improvement in fuel economy numbers for the hybrid vehicle (kmpl), compared to the conventional vehicle, on the urban cycle (UDDS) and highway cycle (HWFET). Also, to analyze and understand the vehicle operating points in terms of engine and motor speed, torque, transmission speeds, pedal positions, gear, distance traveled, battery voltage, current, SoC etc.

Objectives :-

a. Tabulate the fuel economy numbers (kmpl) for UDDS and HWFET cycle. Compare these numbers with the baseline numbers for conventional vehicle model from Project 1.
b. Plot the time trace for engine, transmission input, transmission output and wheel speed on one plot.
c. Plot engine torque, engine power, fuel rate and fuel consumption using subplots.
d. Plot accelerator and brake pedal, gear command, vehicle desired and actual speed, vehicle distance using subplots.
e. Plot the engine operating points on the engine fuel map.
f. Plot motor speed, torque, motor input power using subplots.
g. Plot pack voltage, current and SoC using subplots.
h. Plot the motor operating points on the motor input power map, with the motor max motoring and generating torque curves.

Theory :-

P1 hybrid vehicle architecture -

The P1 architecture, with the electric machine connected directly to the crankshaft, is the solution adopted by Honda on their first generation Integrated Motor Assist (IMA) technology. The electric motor functions as a generator, during vehicle deceleration, as an engine starter, and as a motor (to assist the engine) during vehicle accelerations.

One of the biggest advantage of this solution is that the electric motor can provide higher torque than the BiSG, since there is no belt limitation (due to slip). However, since there is no speed / torque ratio between the electric machine and crankshaft, the torque requirements on the electric motor can be quite demanding.

Two examples of P1 MHEV architectures are:

• Honda Insight Hybrid 2009 (with Integrated Motor Assist technology)
• Mercedes Benz S400 Bluehybrid 2010

For example, the main characteristics of the crankshaft-mounted electric machine for mild hybrid Honda Insight 2009 are summarized in the table below.

Electric machine performance	Maximum torque (at crankshaft): up to 34 Nm Maximum power: 10 kW Efficiency: up to 94%
Hybrid modes (functions)	Idle Stop & Start Moving Stop & Start Engine load shift Torque assist (fill) Torque boost Sailing / Coasting Energy recuperation Brake regeneration
Advantages	Higher efficiency The 12V starter can be removed
Disadvantages	Output torque limited by the size of the electric machine Energy recuperation affected by engine friction losses High impact on existing vehicle architecture Higher overall cost of the electrical components Air cooling not possible for the electric machine
Overall characteristics	Torque Boosting Capability: High (if electric machine is capable) Electrical Energy Recuperation: Medium (due to engine losses) Driveability Improvements: Medium (depending on the torque capability of the electric machine) Electrical Creep / Drive: Possible (depending on the torque capability of the e-machine) Packaging: Difficult components integration (powertrain specially designed for this architecture) System Efficiency: High (no gear mesh or belt losses)

Both P0 and P1 mild hybrid configurations have the electric machines on the engine side, without the possibility of mechanical disconnection. This makes torque boosting and energy recuperation not very efficient because of the torque losses. Moreover, recuperating electrical energy with the engine off, during coasting, is not possible.

Explanation of Given Data :-

“Project2_InitFile.m” is a Matlab script used to load all the variables required for running the Simulink model and for post-processing. The drive cycle selection is also done here. Before running the Simulink vehicle model, run this initialization script.

%% Initialization File
% Initialization file for loading the variables for the Conventional vehicle simulation model

%% Vehicle Parameters
M = 1500; % Vehicle weight [kg]
Cr = 0.015; % Rolling resistance coefficient
Rw = 0.35; % Rolling radius [m]
Cd = 0.33; % Drag coefficient
Af = 2; % Frontal area [m2]
rhoa = 1.225; % Air density [kg/m3]
Vwind = 0; % Wind velocity [kmph]
g = 9.81; % Gravitational acceleration [m/s2]
theta = 0; % Slope [deg]
myu_road_tire = 1; % Coefficient of friction between tire - road interface

%% Powertrain Parameters
FDR = 3.73; % Final Drive Ratio / Diff Ratio
DiffEff = 0.99; % Differential efficiency (assumed independent of operating conditions)

NumGear = 4; % Number of gears in transmission
TransGear = [1:NumGear]; % Transmission Gears
TransRatio = [3.06, 1.62, 1, 0.7]; % Corresponding Transmission ratios
TransEff = 0.90; % Transmission efficiency (assumed independent of operating conditions)

TC_SR = [0, .5, .6, .7, .8, .87, .92, .94, .96, .97, 1]; % Torque Converter Speed Ratio (Matlab default) -> TurbSpd/PumpSpd
TC_TR = [2.232, 1.5462, 1.4058, 1.2746, 1.1528, 1.0732, 1.0192, 1, 1, 1, 1]; % Torque Converter Torque Ratio (Matlab default) -> TurbTrq/PumpTrq
TC_Cf = 1e-4 * [.72558, .66322, .63463, .59042, .51331, .4144, .29287, .22444, .12186, .04386, 0]; % Torque Converter Capacity Factor (Matlab default) -> PumpTrq/PumpSpd^2 [Nm/rpm^2]

load Vehicle_Data/Engine_data_1_9L_Saturn_95kW
load Vehicle_Data/Trans_Shift_map
load Vehicle_Data/EM_Honda_Insight_10kW
load Vehicle_Data/ESS_NiMH6

ESS_init_soc = 0.8;
ESS_soc_max = 0.9;
ESS_soc_min = 0.6;

%% Driver Parameters
Kp = 10; % P gain for driver PI model
Ki = 1; % I gain for driver PI model
Drive_Cycle_Select = 2; % Drive cycle selection

% Drive cycle values in m/s

if Drive_Cycle_Select == 1
load DriveCycles/UDDS;

elseif Drive_Cycle_Select == 2
load DriveCycles/HWFET;

elseif Drive_Cycle_Select == 3
load DriveCycles/FTP;

elseif Drive_Cycle_Select == 4
load DriveCycles/US06;

elseif Drive_Cycle_Select == 5
load DriveCycles/NEDC;

elseif Drive_Cycle_Select == 6
load DriveCycles/WLTP;

end

time_end = cyc_time(end);
vel_end = cyc_vel(end);

“Project2_VehicleModel.slx” is the Simulink model of the vehicle. It is modeled using a ‘Driver’ block, which is a basic PI controller that generates accelerator and brake pedal outputs to match the desired and actual vehicle speeds. The ‘Controller’ block is the brains of the vehicle, representing the electronic controls units. Based on the driver inputs, it generates desired engine torque, desired transmission gear , desired brake torque , desired electric motor torque , clutchLockUp signal. These inputs are fed to the ‘Powertrain’ block which represents the drivetrain of the vehicle. It consists of an ‘Engine’ and 'Electric Motor' connected to the 'Crank Hub' ,which is connected to the ‘Automatic Transmission’ through a ‘Torque Converter’. The output of the transmission is connected to the ’Differential’, which powers the ‘Wheels’, that provides the tractive force for vehicle acceleration. The longitudinal dynamics of the vehicle along with the road load is represented in the ‘Vehicle Dynamics’ block. The solver selected is auto(ode14x) with a fixed step size of 0.01 sec.

All the subsysteam of the above Simulink model is illustrated by step bt step in following way -

I. DRIVER SUBSYSTEAM -

In 'Driver Subsysteam' , drive cycle data is provided in the form of LookUp table.From lookup table we get vehicle required velocity and that subtracted from Actual velocity which is provided as feedback signal from Vehicle subsysteam. This error signal is provided to PI controller , here it calculated Accelration and Brake output signal to match with required velocity. This calculated Accelration and Brake output signal are given to 'Controller Subsysteam'.

II. CONTROLLER SUBSYSTEAM -

In Controller Subsysteam ,There is Mode selection based on the Input signal and feedback signal such as SOC , clutch lockup,Engine speed , Velocity, Accelration and Brake input signal etc.,Theere are 4 mode (Start,Stop,Drive and Regenrative Braking).After selecting Mode , we get some signal we that provide to particular control unit (Engine control unit, Electric Motor control unit,Transmission control unit,Brake control unit).At the end of Controller Subsysteam, we get controlled signals (EngTrqReq,GearCmd,ClutchLockup,EMTrqReq,BrakeTrqReq) that we given as input to powertrain Subsysteam.

III. POWERTRAIN SUBSYSTEAM -

Powertrain Subsysteam consists of various subsysteam such as Engine, Electric Machine, crank hub, Transmission,Differential,Wheel,Vehicle Dynamic. The control signal are provided as a input to particular subsysteam.All details of all this subsysteam are shown in following way-

1. Engine Subsysteam-

In Engine Subsysteam, The engine torque request from engine control unit as a input that will check within range of Max torque curve and min torque curve which are provided in the form of lookup tables.And at the end we will get Engine Torque. Also , from Engine Subsysteam we will get Engine fuel rate and fuel consumption.

2. Electric Machine Subsysteam -

In Electric Machine Subsysteam, The EM torque request from EM control unit as a input that will check within the range of max torque curve and max genration torque curve which are provided in the form of lookup table.At the end we will get EM torque as a output.Also ,here we get EM input power.

3. Crank Hub Subsysteam -

This is very simpe subsysteam where Engine and EM torque get added and we get Crank torque which is provided as input signal to Transmission subsysteam.

4. Transmission Subsysteam -

This Subsysteam is connected to Crank Hub Subsysteam via Torque Converter Subsysteam. From Torque Converter Subsysteam we will get transmission input torque that will get multiplied with gear ratio which is provided in lookup table . This multiplication product then gone through gain block where transmission efficiency get multiplied and we will get Transmission Output Torque.

5. Torque Converter Subsysteam -

This Subsysteam is used to transfer Crank Torque to transmission subsysteam.

6. Differential Subsysteam-

From this subsysteam we get Axle Torque by applying Final Drive Ratio (FDR) and differential efficiency to Transmission output torque.

7. Wheel Subsysteam -

From this subsysteam we get Tractive force and wheel speed.

8. Vehicle Dynamic subsysteam -

Here we get Vehicle velocity and distance travelled by vehicle.

9. Energy Storage Subsysteam -

Here we get SOC , Pack Current and Pack Voltage.

After running this Simulink model, data from the model will be loaded in the Matlab workspace. Then I write the Matlab script to analyze this data and to generate plots. This script needs to be executed after the Simulink model data has been loaded into the workspace.

%% Post-Processing File
% File for post-processing the Conventional vehicle simulation model data

%% Renaming variables
Time = out.tout;
Acc_Pdl = out.Acc_Pdl; % Accelerator pedal [%]
Brk_Pdl = out.Brk_Pdl; % Brake pedal [%]
Gear_Cmd = out.Gear_Cmd; % Transmission gear
Trans_In_Spd = out.Trans_In_Spd*30/pi; % Transmission input speed [rpm]
Trans_Out_Spd = out.Trans_Out_Spd*30/pi;% Transmission output speed [rpm]
Eng_Trq = out.Eng_Trq; % Engine brake torque [Nm]
Eng_Spd = out.Eng_Spd*30/pi; % Engine speed [rpm]
Eng_Fuel_Consump = out.Eng_Fuel_Consumption; % Engine fuel consumption [g]
Veh_Dist = out.Veh_Dist/1000; % Distance traveled by vehicle [km]
Veh_Spd = out.Veh_Spd*18/5; % Vehicle speed [kmph]
wheel_spd = out.wheel_Spd;
Eng_Fuel_Rate = out.Eng_Fuel_Rate;
Motor_spd = out.EM_spd*30/pi;
Motor_trq = out.EM_Trq;
Motor_In_pwr = out.EM_in_pwr;
Pack_voltage = out.Terminal_Voltage;
Pack_current = out.current;
SOC = out.SOC;
Veh_Desired_spd = out.Veh_Req*18/5;

%% Data Analysis
Eng_Pwr = (Eng_Spd*pi/30).*Eng_Trq/1000; % Engine brake power [kW]
rho_petrol = 0.7197; % Density of petrol [kg/L]
kmpl = Veh_Dist(end)/(Eng_Fuel_Consump(end)/1000/rho_petrol) % Fuel economy [kmpl]

%% Plotting vehicle characteristics time trace
figure()
subplot(4,1,1)
hold on
grid on
plot(Time, Acc_Pdl, 'linewidth', 1, 'Color', 'black');
plot(Time, Brk_Pdl, 'linewidth', 1, 'Color', 'red');
ylabel('Pedal [%]')
xlim([0, Time(end)]);
legend('Accel','Brake');
subplot(4,1,2)
hold on
grid on
plot(Time,Veh_Spd, 'linewidth', 1, 'Color', 'black');
plot(Time,Veh_Desired_spd, 'linewidth', 1, 'Color', 'red');
ylabel('Speed [Kmph]')
xlim([0, Time(end)]);
ylim([0, 6000]);
legend('Veh Actual spd','Veh Desired spd');
subplot(4,1,3)
hold on
grid on
plot(Time,Veh_Dist, 'linewidth', 1, 'Color', 'black');
xlim([0, Time(end)]);
ylim([0,Veh_Dist(end)]);
xlabel('Time [s]');
ylabel('Veh Dist');
legend('Veh Dist travelled');
subplot(4,1,4)
hold on
grid on
plot(Time, Gear_Cmd, 'linewidth', 1, 'Color', 'black');
xlim([0, Time(end)]);
xlabel('Time [s]');
ylabel('Gear');
legend('Gear command');

%% Plotting engine operating points on engine fuel map
figure('Name','Engine Operating Points');
hold on
grid on
title('Engine Operating Points','fontsize',12);
p1=plot(Eng_map_spd*30/pi,Eng_max_trq,'linewidth',2,'color','r');
p2=line([Eng_map_spd(end)*30/pi Eng_map_spd(end)*30/pi],[0 Eng_max_trq(end)]);
set(p2,'linewidth',1,'linestyle','--','color','k');
p3=line([Eng_map_spd(1)*30/pi Eng_map_spd(1)*30/pi],[0 Eng_max_trq(1)]);
set(p3,'linewidth',1,'linestyle','--','color','k');
[c,h] = contour(Eng_map_spd'*30/pi,Eng_map_trq,Eng_fuel_map');
clabel(c,h);
xlabel('Engine Speed [rpm]');
ylabel('Engine Torque [Nm]');
title('Engine Fuel Consumption Map [g/s]');
p4 = plot(Eng_Spd,Eng_Trq,'.','color','k');
legend([p1 p4],{'Max Curve','Operating Points'});
axis([Eng_map_spd(1)*30/pi Eng_map_spd(end)*30/pi 0 Eng_map_trq(end)]);

%% Plotting engine torque, engine power,fuel consumption

figure()
subplot(4,1,1)
hold on
grid on
plot(Time,Eng_Trq , 'linewidth', 1, 'Color', 'black');
ylabel('engine torque')
xlim([0, Time(end)]);
legend('engine torque');
subplot(4,1,2)
hold on
grid on
plot(Time,Eng_Pwr, 'linewidth', 1, 'Color', 'red');
ylabel('Eng Pwr')
xlim([0, Time(end)]);
legend('Eng Pwr');
subplot(4,1,3)
hold on
grid on
plot(Time,Eng_Fuel_Consump, 'linewidth', 1, 'Color', 'green');
xlim([0, Time(end)]);
xlabel('Time [s]');
ylabel('Eng Fuel Consump');
subplot(4,1,4)
hold on
grid on
plot(Time,Eng_Fuel_Rate, 'linewidth', 1, 'Color', 'red');
ylabel('Eng Fuel Rate')
xlim([0, Time(end)]);
legend('Eng Fuel Rate');

%% Plotting engine speed, transmission input,transmission output,wheel speed

figure()
hold on
grid on
plot(Time,Eng_Spd,'linewidth', 1, 'Color', 'green');
plot(Time, Trans_In_Spd, 'linewidth', 1, 'Color', 'black');
plot(Time, Trans_Out_Spd, 'linewidth', 1, 'Color', 'red');
plot(Time,wheel_spd,'linewidth', 1, 'Color', 'blue');
xlim([0, Time(end)]);
xlabel('Time [s]');
ylabel('speed');
legend('Eng Spd','Trans Input','Trans Output','wheel spd');

%% Plot pack voltage, current and SoC using subplots

figure()
subplot(3,1,1)
hold on
grid on
plot(Time,Pack_voltage , 'linewidth', 1, 'Color', 'black');
ylabel('Pack voltage')
xlim([0, Time(end)]);
legend('Pack voltage');
subplot(3,1,2)
hold on
grid on
plot(Time,Pack_current, 'linewidth', 1, 'Color', 'black');
ylabel('Pack current')
xlim([0, Time(end)]);
legend('Pack current');
subplot(3,1,3)
hold on
grid on
plot(Time,SOC, 'linewidth', 1, 'Color', 'black');
ylabel('SOC')
xlim([0, Time(end)]);
legend('SOC');

%% Plot motor speed, torque, motor input power using subplots
figure()
subplot(3,1,1)
hold on
grid on
plot(Time,Motor_spd , 'linewidth', 1, 'Color', 'black');
ylabel('Motor speed')
xlim([0, Time(end)]);
legend('Motor speed');
subplot(3,1,2)
hold on
grid on
plot(Time,Motor_trq , 'linewidth', 1, 'Color', 'black');
ylabel('Motor Torque')
xlim([0, Time(end)]);
legend('Motor Torque');
subplot(3,1,3)
hold on
grid on
plot(Time,Motor_In_pwr , 'linewidth', 1, 'Color', 'black');
ylabel('Motor Input power')
xlim([0, Time(end)]);
legend('Motor Input power');

%% Plot the motor operating points on the motor input power map, with the motor max
% motoring and generating torque curves
figure('Name','Motor Operating Points');
hold on
grid on
title('Motor Operating Points','fontsize',12);
q1=plot(EM_map_spd*30/pi,EM_max_trq,'linewidth',2,'color','r');
q2=plot(EM_map_spd*30/pi,EM_max_gen_trq,'linewidth',2,'color','r');
q3=line([EM_map_spd(end)*30/pi EM_map_spd(end)*30/pi],[EM_map_trq(1) EM_map_trq(end)]);
set(q3,'linewidth',1,'linestyle','--','color','k');
q4=line([EM_map_spd(1)*30/pi EM_map_spd(1)*30/pi],[EM_map_trq(1) EM_map_trq(end)]);
set(q4,'linewidth',1,'linestyle','--','color','k');
[c,h] = contour(EM_map_spd'*30/pi,EM_map_trq,EM_inpwr_map');
clabel(c,h);
xlabel('Motor Speed [rpm]');
ylabel('Motor Torque [Nm]');
title('motor input power map [W]');
q5 = plot(Motor_spd,Motor_trq,'.','color','k');
legend([q1 q2 q5],{'Max Torque Curve','EM max gen trq','Operating Points'});
axis([EM_map_spd(1)*30/pi EM_map_spd(end)*30/pi EM_map_trq(1) EM_map_trq(end)]);

After Running this Matlab Code we will get following Result .

Result :-

a. Tabulate the fuel economy numbers (kmpl) for UDDS and HWFET cycle. Compare these
numbers with the baseline numbers for conventional vehicle model from Project 1.

* The fuel economy numbers (kmpl) comparision for UDDS cycle.

* The fuel economy numbers (kmpl) comparision for HWFET cycle.

From above Fuel economy numbers we observed that Fuel economy of P1 hybrid vehicle is greater than that of Conventional vehicle.

b. Plot the time trace for engine, transmission input, transmission output and wheel speed
on one plot.

#For UDDS cycle -

# For HWFET cycle -

The above graph for both cycle show variation for engine, transmission input, transmission output and wheel speed.

c. Plot engine torque, engine power, fuel rate and fuel consumption using subplots.

#For UDDS cycle -

# For HWFET cycle -

The above plots shows the variation in engine torque,engine power ,fuel rate and fuel consumption.As the requirement of engine torque and power increases,the fuel rate also get increased.

d. Plot accelerator and brake pedal, gear command, vehicle desired and actual speed,
vehicle distance using subplots.

#For UDDS cycle -

# For HWFET cycle -

The above plots shows the variation in accelerator and brake pedal, gear command, vehicle desired and actual speed .Also the distance travelled by vehicle is shown in above plot.

e. Plot the engine operating points on the engine fuel map.

#For UDDS cycle -

# For HWFET cycle -

The engine operating points are speed and torque points obtained from simulation results, which is plotted on the speed and torque input map showing the area where the engine operates with respect to the data provided.

For a given power requirement, the number of gears in a transmision provide the number of operating points for the powertrain in terms of torque and speed.

In the above images the operating points are shown by "." .

f. Plot motor speed, torque, motor input power using subplots.

#For UDDS cycle -

# For HWFET cycle -

The above plot shows the variation of motor speed, torque, motor input power.

g. Plot pack voltage, current and SoC using subplots.

#For UDDS cycle -

# For HWFET cycle -

The above plot shows the variation of pack voltage, current and SoC.

h. Plot the motor operating points on the motor input power map, with the motor max
motoring and generating torque curves.

#For UDDS cycle -

# For HWFET cycle -

The motor operating points are speed and torque points obtained from simulation results, which is plotted on the speed and torque input map showing the area where the motor operates with respect to the data provided.

In the above images the operating points are shown by "." .

Conclusion :-

From this project I understand the functionality of P1 hybrid and how to model it . Also , I understand the how to use matlab and simulink for writting script and modelling.After completing this project I am able to analyze P1 hybrid over conventional vehicle.