Final Project: Electric Rickshaw modelling

Aim:

Create a detailed MATLAB model of an electric rickshaw (three wheel passenger vehicle) as per details below:

Rear wheels driven by PM brushed type motor

Assume efficiency points of motor controller and motor

Objective:

For any three standard driving cycles show energy consumption, temperature rise of motor

controller for 100 km constant speed driving at 45 kmph.

Vehicle Model:

The entire model is divided in to 4 parts

1. Toatl Vehicle Body
2. Motor and controller
3. Battery
4. Driver and drive cycle

1.Total Vehicle Body:

It is created as a subsystem

It is Rear wheel Drive. The motor axil is connected to the Rare wheels axil.

It is a combination of different parts

1. vehicle body
2. Wheels
3. Simple gear

As it is the 3 wheeler i.e., front has 1 wheel and rare has 2 wheels. It is a rear wheel drvie i.e., the motor is connected to the rear wheels through a gear box. The front wheel will rotate freely.

Vehicle body:

The Vehicle Body block represents a two-axle vehicle body in longitudinal motion. The vehicle can have the same or a different number of wheels on each axle. For example, two wheels on the front axle and one wheel on the rear axle. The vehicle wheels are assumed identical in size. The vehicle can also have a center of gravity (CG) that is at or below the plane of travel.

The block accounts for body mass, aerodynamic drag, road incline, and weight distribution between axles due to acceleration and road profile. Optionally include pitch and suspension dynamics. The vehicle does not move vertically relative to the ground.

The block has an option to include an externally-defined mass and an externally-defined inertia. The mass, inertia, and center of gravity of the vehicle body can vary over the course of simulation in response to system changes.

Inputs:

W = head wind speed = 0 m/s (let us assume it has no opp wind speed)

Beta = Road incline angle = 0 rad (let us assume there is no road inclination)

H = Horizontal motion - Connect tire traction motion to this port.

Output:

NR = Rear axil normal force (N)

FR = front axil normal force (N)

V = Velocity (m/s)

Input parameters:

\

All other are default values

wheels:

The Tire (Magic Formula) block models a tire with longitudinal behavior given by the Magic Formula [1], an empirical equation based on four fitting coefficients. The block can model tire dynamics under constant or variable pavement conditions.

The longitudinal direction of the tire is the same as its direction of motion as it rolls on pavement. This block is a structural component based on the Tire-road Interaction (Magic Formula) block.

To increase the fidelity of the tire model, you can specify properties such as tire compliance, inertia, and rolling resistance. However, these properties increase the complexity of the tire model and can slow down simulation. Consider ignoring tire compliance and inertia if simulating the model in real time or if preparing the model for hardware-in-the-loop (HIL) simulation.

A = Axil

H = Hub

S = slip = 0

N = Normal force

input parameters:

All other parameters are default values

Simple gear:

The Simple Gear block represents a gearbox that constrains the connected driveline axes of the base gear, B, and the follower gear, F, to corotate with a fixed ratio that you specify. You choose whether the follower axis rotates in the same or opposite direction as the base axis. If they rotate in the same direction, the angular velocity of the follower, ω_F, and the angular velocity of the base, ω_B, have the same sign. If they rotate in opposite directions, ω_F and ω_B have opposite signs.

F = Follower = Rotational mechanical conserving port associated with the follower, or output, shaft.

B = base = Rotational mechanical conserving port associated with the base, or input, shaft. It is connected to the motor Output

Input parameters:

Other blocks are

Terminator

Use the PS Terminator block to cap physical signal output ports that do not connect to other blocks.

Unlike conserving ports in physical modeling, or Simulink^® output ports, unconnected physical signal output ports do not generate warnings. However, you can use a PS Terminator block for clarity, to indicate that the signal was not inadvertently left unconnected.

As the slip is considered as zero it should be terminated using the terminator

Rotational free end:

The Rotational Free End block represents a mechanical rotational port that rotates freely, without torque.

You can use this block to terminate mechanical rotational ports on other blocks that you want to leave unconnected. This is not necessary because if you leave a conserving port unconnected, the physical network sets all the Through variables at that port to 0. However, terminator blocks improve diagram readability.

You can also use this block to set the initial rotational velocity at a node.

As the front wheel is not connected to any axil so it is connected to Rotational free end.

2. Motor and controller:

It is combination of

1. DC motor
2. H-Bridge
3. Controlled PWM Voltage
4. Controlled volatge source
5. Current sensor

DC Motor:

R = motor rotor = it is connected to shaft of the vehicle body

C = case = Mechanical rotational conserving port associated with the DC motor case, as it is stationary part it is conneted to Mechanical Rotational Referance

+ = positive termial of the motor, connected to H-Bridge output + termial

- = Negitive termial of the motor, connected to H-Bridge output - termial

The parameters are taken as

Thermal Parameters:

All other parameters are taken default values.

H-Bridge:

It is used to control the Motor speed and direction accorting to the drive cycle.

+ = Positive terminal of the H-Bridge, It is a output of the H-bridge connected to + of the motor

- = Negitive terminal of the H-Bridge, It is a output of the H-bridge connected to - of the motor

PWM = input signal, it is connected to the PWM pulse generater

REF = Referance, it is connected to Electrical ground

REV = Reverse of the motor, it is connected to ground because we are assuming that vehicle is going only in one froward direction.

BRK = Break, it is connected to the Driver through the Controlled voltage source.

Its parameters are taken as:

All other parameters are taken as defult values.

Controlled PWM Voltage:

PWM = Pulse output, connected to H-Bridge PWM port. It geneartes the requried duty cycle for the H-Bridge according to the Drive Cycle.

REF = referance , it is connected to the electrical referance

ref+ = Referance voltage, it is the drive cycle referance voltage input

ref- = ground

All other parameters are taken as default values.

Controlled Voltage Source:

The Controlled Voltage Source block represents an ideal voltage source that is powerful enough to maintain the specified voltage at its output regardless of the current flowing through the source.

The output voltage is V = Vs, where Vs is the numerical value presented at the physical signal port.

Generates the voltage from driver for the Controlled PWM Voltage referance voltage, so that the Controlled PWM Voltage can generate the Duty cycle as required

Signal port is connected to the Longitudinal Driver Aceleration port. Another Controlled voltage source signal port is connected to Longitudinal Driver deceleration port. So that the required voltage is generated for Acceleration and deceleration for H- Bridge.

Current Sensor:

The Current Sensor block represents an ideal current sensor, that is, a device that converts current measured in any electrical branch into a physical signal proportional to the current.

Connections + and – are electrical conserving ports through which the sensor is inserted into the circuit. Connection I is a physical signal port that outputs the measurement result.

Used to measure the current flowing through the Motor.

Temperature Sensor:

The Temperature Sensor block represents an ideal temperature sensor, that is, a device that determines the temperature differential measured between two points without drawing any heat.

Connections A and B are thermal conserving ports that connect to the two points where temperature is being monitored. Port T is a physical signal port that outputs the temperature differential value.

The block positive direction is from port A to port B. The measured temperature is determined as T = T_A – T_B.

Thermal Reference:

The Thermal Reference block represents a thermal reference point, that is, a point with an absolute zero temperature, with respect to which all the temperatures in the system are determined.

Electrical referance:

The Electrical Reference block represents an electrical ground. Electrical conserving ports of all the blocks that are directly connected to ground must be connected to an Electrical Reference block. A model with electrical elements must contain at least one Electrical Reference block.

Solver Configuration:

Each physical network represented by a connected Simscape™ block diagram requires solver settings information for simulation. The Solver Configuration block specifies the solver parameters that your model needs before you can begin simulation.

Each topologically distinct Simscape block diagram requires exactly one Solver Configuration block to be connected to it.

3. Battery:

3. Battery:

The Battery block implements a generic dynamic model that represents most popular types of rechargeable batteries.

The blockparameters:

Energy calculation is done by the formula `(P*t)/1000` KWh

Power (P) = Voltage * Current

integrating it gives the Energy consmption in Watts and dividing it with 3600 gives Watt-Hour

Controlled Current Source:

The Controlled Current Source block converts the Simulink^® input signal into an equivalent current source. The generated current is driven by the input signal of the block. The positive current direction is as shown by the arrow in the block icon.

You can initialize the Controlled Current Source block with a specific AC or DC current. If you want to start the simulation in steady state, the block input must be connected to a signal starting as a sinusoidal or DC waveform corresponding to the initial values.

It gets the control single from the H-Bridge current measurnment block.

4. Driver and drive cycle:

Longitudinal Driver:

The Longitudinal Driver block implements a longitudinal speed-tracking controller. Based on reference and feedback velocities, the block generates normalized acceleration and braking commands that can vary from 0 through 1. You can use the block to model the dynamic response of a driver or to generate the commands necessary to track a longitudinal drive cycle.

Parameters:

Drive cycles:

The Drive Cycle Source block generates a standard or user-specified longitudinal drive cycle. The block output is the specified vehicle longitudinal speed, which you can use to:

For the drive cycles, you can use:

1. FTP75

2.WOT:

3. Created drive cycle:

Results:

Case - 1

For any three standard driving cycles show energy consumption, temperature rise of motor and controller

1. FTP75 drive cycle

The vehicle is following the drive cycle almost.

The total distance travelled is 5.6 km in 2474 sec

Battery SoC at the end of the drive cycle is 95%

The Energy consumption is 2.5 KWh for the distance of 5.6 km in 2474 sec

The Temperature of the Motor is increasing gradually, at the end of the drive cycle the temperature is 540K (266.85 °C)

The Temperature of the Controller is increasing gradually, at the end of the drive cycle the temperature is 386K (112.85 °C)

2. WOT Drive Cycle:

The vehicle is following the drive cycle and stabled at 25 sec.

The total distance travelled is 0.89 km in 120 sec

Battery SoC at the end of the drive cycle is 98%

The Energy consumption is 1 KWh for the distance of 0.89 km in 120 sec

The Temperature of the Motor is increasing gradually, at the end of the drive cycle the temperature is 360K (86.85 °C)

The Temperature of the Controller is increasing gradually, at the end of the drive cycle the temperature is 327K (53.85 °C)

3. Creted Drive cycle:

The vehicle is following the drive cycle almost.

The total distance travelled is 0.97 km in 360 sec

Battery SoC at the end of the drive cycle is 99.18%

The Energy consumption is 1 KWh for the distance of 0.97 km in 360 sec

The Temperature of the Motor is increasing gradually, at the end of the drive cycle the temperature is 500K (226.85 °C)

The Temperature of the Controller is increasing gradually, at the end of the drive cycle the temperature is 376.5K (103.35 °C)

Case -2

Vehicle Runed for 100 km constant speed driving at 45 kmph.

The vehicle is following the drive cycle.

The total distance travelled is 100.7 km in 29000 sec

Battery SoC at the end of the drive cycle is 20%

The Energy consumption is 40 KWh for the distance of 100.7 km in 360 sec

The Temperature of the Motor is increasing gradually, at the end of the drive cycle the temperature is 487.5K (211.85 °C)

The Temperature of the Controller is increasing gradually, at the end of the drive cycle the temperature is 373K (99.85 °C)

Conclusion:

It is better to be operate the controller temperature below 80°C and for motor is below 100°C. But in our model the temperatures are beyond the save values. It will damage the motor and controller if the temperature is exceded the save values. to avoid that the Cooling System is arranged for motor and controller which will mataintain the temperature of the motor and controller in save values.