Project 2
The engine-to-wheel, rear-to-front, and cause-and-effect methods are other names for the forward modelling methodology. Calculation flows from engine to wheel in the same direction as positive power flow.
· This method is based on equations for vehicle dynamics, the behaviour of individual powertrain parts, and their dynamic interplay.
· Moreover, a driver controller is necessary to guide the vehicle at a desired speed and establish the commencement of the calculations. The controller is set up to simulate how the driver will operate the brakes or the accelerator to match the intended speed, allowing for the study of driver behaviour. The controller is utilized as a component of a feedback loop to calculate the amount of energy necessary to power the vehicle.
Vehicle Model:-
All the variables required to run and post-process the Simulink model have been loaded using a MATLAB script. From here, you may also choose the drive cycle. The script is initialized at MATLAB to load all the workspace variables before the Simulink vehicle model is run
%% 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]
mu_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 condition)
TC_SR = [0, .5, .6, .7, .8, .87, .92, .94, .96, .97, 1]; % Torque Converter Speed Ratio
TC_TR = [2.232, 1.5462, 1.4058, 1.2746, 1.1528, 1.0732, 1.0192, 1, 1, 1, 1]; % Torque _______ Converter Torque Ratio
TC_Cf = 1e-4 * [.72558, .66322, .63463, .59042, .51331, .4144, .29287, .22444, .12186, .04386, 0]; % Torque Converter Capacity Factor
ESS_init_soc = 0.8;
ESS_soc_max = 0.9;
ESS_soc_min = 0.6;
%% Driver Parameters %%
Kp = 11.5; % P gain for driver PI model
Ki = 1.7; % 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
Simulink Modelling:-
The driver model, control model, and powertrain block are the three basic sub-blocks used to form the convection model in Simulink.
· The controller block sends control signals for engine torque, gear shifting, and brake torque to the Powertrain model while the driver block receives feedback on the actual vehicle speed and supplies the controller block with the necessary acceleration or braking output.
Drive Model
· A fundamental PI controller called Driver Model produces outputs from the accelerator and brake pedals that are matched to the desired and actual vehicle speeds.
· By giving the controller output for the accelerator and brake pedals, the PI controller manages the discrepancy between the needed driving cycle and the actual vehicle speed.
Controller Model
· The vehicle's "Controller block," which stands in for the electronic control modules, is its brain. It produces the required engine torque, desired motor torque, desired transmission gear, and desired brake torque based on the driver's inputs.
· The supervisory control unit, which selects the operation modes (start/stop, cruise, or regeneration braking mode. The engine drive and the motor drive are adjusted for each mode.
The driver unit's input for the accelerator and brake pedals, the engine's actual speed, the vehicle's actual speed, the SOC status, and the clutch lockup state are the inputs for the state flow charts. Moreover, the Mode, Engine On/Off Request, Engine Input Throttle, and Electric Motor Input Throttle are the State flow Outputs to the Individual Controllers.
· The controller is made up of an electric motor control unit, a brake control unit, an engine control unit, and a transmission control unit.
· The transmission model, which depicts the drive train, receives all control signals again.
Engine Control Unit
Idle Speed Controller
Engine management system Give the engine block the necessary torque command by comparing engine speed to the lookup table's maximum and lowest torque curves. To estimate the torque input needed for the engine, the throttle input is combined with the idle speed throttle and gains with the torque output from the lookup table.
Electric Motor Control Unit
Drive Motor Unit Give the Electric Motor the necessary torque command by comparing its speed to the maximum torque curve and maximum torque generation curves in the lookup table. In order to compare the lookup tables and determine the torque input needed for the E-Motor, the EM throttle input is employed.
Brake Control Unit
Powertrain Model
All the parts that transform an engine's power into motion are included in the powertrain model.
· This covers the subsystems for the vehicle's body dynamics as well as the engine, battery pack, electric motor, crank hub, transmission, differential, wheels, and wheels.
· The appropriate blocks in the powertrain model get the control signals from the control model through a bus.
Battery Model
SOC Estimation Model
Pack current in Ampere (A) is converted to AmpHour (Ah), and the Initial SOC and Max Capacity are added.
· The SOC value is
restricted to the range of 0 to 1 to identify the SOC of the battery at each
instance.