Final Project: Design of an Electric Vehicle
Aim :- model a electrical vehicle as per given desired condition or standard or parameter is given by the reference or makers.
Procedure follows :-
(a) Making vehicle design
Drive cycle
Driver controller
Power convertor h-bridge
Battery charge and discharge
Motor (permanent magnet DC)
Vehicle body
(b) Model parameter
(c) Results
Drive Cycle :-
A drive cycle involves a sequence of driving conditions that include a mix of urban and highway driving, different speeds, accelerations, and decelerations. The cycle may also include idling, hot and cold starts, and other variables that affect emissions and fuel consumption.
Drive cycles are used to evaluate the performance and emissions of vehicles, as well as to develop and calibrate onboard diagnostic systems (OBD) that monitor and control emissions in real-world driving conditions. They are also used to establish regulations and standards for vehicle emissions and fuel economy and here I use FTP75.
Driver Controller (longitudinal driver):-
The Driver Controller block that is used a model-based design. It is use to model the behavior of a driver controller, which is a component of a vehicle's control system.
The Driver Controller block takes input signals, such as vehicle speed and acceleration, and uses them to calculate the appropriate control signals for the driver controller. These control signals are sent to other blocks in the Simulink model, which simulate the behavior of other components of the vehicle control system, such as the engine or transmission.
The Driver Controller block can be customized to model different types of driver controllers, depending on the specific requirements of the simulation. Some examples of driver controllers that can be modeled using the Driver Controller block include cruise control, adaptive cruise control, and lane keeping assist.
Ports
VelRef port is the reference velocity port where the input drive cycle data is fed.
VelFdbk port corresponds to the feedback velocity. The actual velocity output given by the vehicle body is connected here. By comparing the actual (feedback) velocity with the reference velocity, the driver block generates acceleration and braking signals in order to minimize the error between the two concerned velocities.
Grade corresponds to the grade angle. For this simulation, no inclination is considered and hence, a constant block with value 0 is connected.
Info gives the output for the bus signal for different block calculations like difference in reference vehicle speed and vehicle speed, etc.
AccelCmd & DecelCmd correspond to the acceleration and deceleration commands generated respectively and are connected to the corresponding ports of the Controlled PWM Voltage block.
Controlled PWM voltage signal block :-
It generates a Pulse Width Modulation (PWM) waveform with a controllable duty cycle and frequency. The block typically has inputs for the reference signal, which is the desired voltage to be generated, and a modulation index, which determines the amplitude of the PWM waveform. The block also has outputs for the PWM waveform and its complementary signal.
Ports
The PWM & REF connections are for the corresponding ports on the H-Bridge circuit.
The 2 reference inputs correspond to the throttle inputs given by the driver. The block generates corresponding pulse width as per the accelerations and brakes applied by the driver himself.
In this project as PWM frequency signal 3000Hz
Power convertor h-bridge :-
The H-bridge Simulink block typically has inputs for the DC input voltage and a control signal that determines the duty cycle of the output waveform. The block also has outputs for the AC output voltage and current.
The H-bridge circuit consists of four switches arranged in an H-shaped configuration. By turning on and off these switches in a specific sequence, the H-bridge circuit can generate an AC output waveform with a controllable voltage and frequency.
In this project H-bridge take PWM controlled signal from control PWM voltage generator.
Battery charge and discharge :-
To model the Battery pack, a simple Battery block is used. This is because, if the generic battery block is used instead, the simulation will run for a much longer time.
Here, the selected option for Battery Charge Capacity is Finite. Accordingly, the block models the battery as a series internal resistance plus a charge-dependent voltage source.
If the chosen option had been Infinite, the voltage source would have been constant.
Also, the self-discharging of the battery and the battery dynamics are disabled.
The Battery Nominal Voltage is given as 300V.
The Ampere-hour rating is assumed to be 50.
Motor (permanent magnet DC) :-
The DC Motor block represents the electrical and torque characteristics of a DC motor using the following equivalent circuit model and its provide mechanical output.
In this project we use rated PM-DC motor speed at no load is 8000rpm and at load condition 5000
And its supply voltage of the motor is 300V.
Battery state of charge :-
State of charge (SoC) refers to the amount of electrical energy that is currently stored in a battery or other energy storage system, expressed as a percentage of its total capacity. It indicates how much of the battery's available energy has been used and how much remains. For example, a battery that is fully charged has a SoC of 100%, while a battery that is completely discharged has a SoC of 0%. SoC is an important parameter to monitor when using batteries, as it can affect the battery's performance and lifespan.
SOC = (Q/Qmax) x 100%
Solver Configuration :-
A Solver Configuration is added to ensure proper solving of the mathematical equations by the model.
Vehicle body :-
The block typically has inputs for the external forces and torques acting on the body, such as those from the wheels, suspension, and aerodynamic effects. It also has outputs for the position, velocity, and orientation of the body, which can be used to connect to other blocks in the simulation.
The Vehicle Body block can be useful for simulating vehicle dynamics and evaluating the performance of different suspension and control systems.
This 2 axle (4 wheel) assembly is now connected to a Velocity Body Simscape block.
This block basically represents a two-axle vehicle body in longitudinal motion. The block accounts for -
body mass,
aerodynamic drag,
road incline,
weight distribution between axles due to acceleration
road profile.
Here, the connection H is the mechanical translational conserving port hub.
NF & NR correspond to the output ports for normal reaction forces on front axle and rear axle wheels respectively.
Connection V represents the actual output translational velocity of the vehicle.
beta is the road inclination angle & W corresponds to the headwind speed (headwind - direction opposite to that of vehicle).
And the specified parameters are shown in the pic.
Tire
The wheels are modelled using simple Tire (Magic formula) simulink blocks.
The N port of the tire corresponds to the Normal Reaction acting on it.
The A port corresponds to the Mechanical Rotational conserving port for the wheel axle. Thus both the wheels on the same axle should form a connection through their respective A ports.
Connection H corresponds to the Mechanical Translational conserving port for the wheel hub through which the thrust developed by the tire is applied to the vehicle. Thus, all the 4 wheels form a connection through their respective H ports and this is in turn connected to the translational hub of the vehicle body.
The connection S represents the output port for slip of the tire.
Output of the system :- Here we can see the vehicle speed velocity is very stable and state of charge of the vehicle is starts from zero.