Electric Rickshaw Modelling

Aim

1) To Model, an Electric Rickshaw (Three wheeled passenger vehicle) using MATLAB/Simulink

2)To drive the vehicle using Permanent Magnet brushed type motor

3)To check the efficiency of the system

4)To create a custom drive cycle using an excel sheet

5)To check the energy consumption and temperature rise of motor and controller for (HWFET, EUDC, Artemis Motorway 130kmph) drive

cycles

Model Specification and Parameters

Vehicle Model

• The Vehicle model here is a Rickshaw which is a three-wheeled vehicle which is one of the most popular modes of transport in the world.
• The first Rickshaw was developed in 1897 in Japan and was a pulled rickshaw over a period of time rickshaw were redesigned and were equipped with an IC engine and in about 21 centuries, rickshaws were the most popular and cheap vehicle. In India, there are about 1.5M rickshaws.

• Hence with the increase in the number of rickshaws, there was an increase in the number of CO₂ levels and hence there is furthermore necessary to

modify and redesign the vehicle not only to make it more efficient but also environmentally friendly.

• Hence the objective of this project is to design an electric rickshaw which is been driven by a PM brushed type motor and lithium-ion battery as a source using MATLAB/Simulink.
• The Vehicle model is a complete arrangement of the vehicle which contains the block of Vehicle dynamics and Electric Systems. Let us understand each and every block in detail.

Vehicle Dynamics

The subsystem for vehicle dynamics is shown below

• The Block of Vehicle Dynamics contains the vehicle body and wheels of the vehicle

Vehicle Body

• The vehicle body is equipped with aerodynamic drag forces, road inclination angle, vehicle mass, and weight distribution on the axle of the wheels.

• The port NR and NF are the normal forces acting on the rear and front of wheels and V is the velocity of the vehicle and H is a mechanical

translation motion acting in a horizontal direction.

Parameters for the Vehicle Body

Mass	300 kg
Number of Wheels per axle	2
Frontal Area	3 m^2
Drag coefficient	0.4
Air density	1.18 kg/m^3

Wheels

• The tire represents a longitudinal behavior along with a magic formula, the magic formula is nothing but a characteristic function of stiffness, shape, peak, and curvature.

• This vehicle is rear wheeled driven by a Permanent magnet dc motor is connected to the rear axle of the wheels
• The ports A represents the axle of wheels, S represents the slip of the tires, N is the normal forces and H is wheels hub which transmits the thrust to vehicle.

• The axle of the wheels is connected to a torque differentiator which is basically a set of planetary gears, it matches the drive shaft gear to the crown gear it produces a positive tire and vehicle motion.

Parameters of Wheels

Wheel Radius	0.3 m
Vertical Load	3000 N
Slip	10

• The brake of Disk type is used in the vehicle where port S is a conserving rotational terminal which is connected to the axle and port P is a physical signal

representing the cylindrical press.

Electrical System

• The electric system block consists subsystem of motor/motor controller and battery system the motor used here is a permanent magnet brushed dc motor and an H bridge motor controller and the battery used is a lithium-ion battery.

1)Motor/Motor Controller

• The PM brushed motor is an internally commuted motor that runs on direct current. The rotor of this motor consists of 2 or more windings these windings energizes and produces magnetic fluxes.
• The magnetic poles of the rotor will be attracted to opposite pole generated by the stator, causing the rotor to turn.
• The motor can also be run in the opposite direction by just reversing the field connections of the motor.
• Dc motor offers a good speed control and over a wide range by changing the armature or field voltage.
• It also offers a high torque it can start/stop efficiently to cope with the required application.
• Dc motor is free from harmonics voltage and current. Harmonics in AC motor can cause torque pulsation, resulting in the decrease of torque.

• The motor is connected to the H bridge via a current sensor, the battery discharges through this current sensor by a current control source.
• H bridge controller is nothing but helps to control the speed of the motor in reverse and forward direction, the ckt arrangement of h bridge is a combination of four switches connected in an H manner.
• These switches are nothing but transistors(PMOs), hence alternative opening and closing of transistors help us to control the speed of the motor.
• To turn these switches high and low we required to use a pulse width modulation by which a positive and negative reference voltage is generated.
• This positive and negative signal is nothing but an accelerator and decelerator command receiving from a driver, a voltage control source is connected as an interface between an Acc/Dec cmd and PWM to maintain the constant voltage signal.
• The motor port C is a mechanical conserving port that is connected to the mechanical reference and the port R is connected to the axle of the wheels.
• The torque input is scaled using a lookup table taking input as a vehicle speed in Nm.
• To enable the thermal port on the motor and controller just right-clicked on the block ⇒Simscape ⇒ Block Choice ⇒ Show thermal port.
• The temperature can be measured by using a temperature sensor, temperature source and a heat flow rate source which could maintain a constant heat flow.

• Similarly, torque and speed can be monitored using torque and speed sensors.

Parameters of Motor

Armature Inductance	1e-3 H
No-load speed	5000 rpm
Rated Speed	2500 rpm
Rated Load	1200 W
Rated DC Supply	12 V
Rotor Inertia	0.01

Parameter of Motor Controller

Threshold Voltage	2.5 V
PWM Amplitude	5 V
Reverse Threshold	2.5 V
Braking Voltage	2.5 V
Output Voltage	12 V

• To calculate the output power of the system a mathematical expression

P_out = 2pi*N*T/60

where

N = Speed(rpm)

T = Torque(N*m)

• To calculate System Efficiency

E_ff = P_out / P_in

where

P_in = V*I

Battery System

• The battery used in the system is a Lithium-ion battery, the lithium-ion battery is the most efficient battery and is most commonly used in the electric vehicle.
• The lithium-ion battery is easy to replace and requires less maintenance than any other battery.
• Also, the life span of the battery is long and is also environment friendly and benefits over other fossils fuels.

Parameters of Battery

Nominal Voltage	12 V
Rated Capacity	100 Ah
Internal Resistance	0.0012 Ohm

Driver

• The Driver block takes input as a positive reference speed and error is generated by a vehicle speed this error is corrected by a PID controller whose values for the PID are manually tuned and output of it is saturated using an upper and lower limit.

Energy Consumption

• The energy consumption is calculated on the basis of the road load. The total force is a sum of all forcers i.e.

F_TOT = F_i + F_s + F_r + F_a

where

F_i = Inertial Force

F_s = Road slope force

F_r = Road load force

F_a = Aerodynamic drag force

1. F_i (N) = m_v * a_v

where

m_v = vehicle mass(kg)

a_v = vehicle acceleration

1. F_s (N) = m_v * g * sinα

where

g = 9.81 m/s²

α = road slope angle

• F_r (N) = m_v * g * C_rr *cos(α_s)

where

C_rr = Road rolling resistance coefficient

1. F_a(N) = 0.5 * ρ * C_d * A * V_v²

where

ρ = Air density

C_d = Drag coefficient

A = Frontal Area

V_v = vehicle speed

The total power is calculated as a product of total force i.e. F_TOT and vehicle speed

P_TOT = F_TOT * V_v

By integrating the total power w.r.t time we get the total power consumption

E_TOT = ∫ P_TOT dt

Performance Analysis and Result

• Now we run the simulation for three different drive cycles and observe its performance and result.
• Simulation to be performed on the following drive cycle.

1. HWFET (765 Second)
2. EUDC (400 seconds)
3. Artemis Motorway(130kmph)

HWFET (765 Second)

HWFET (Highway Fuel Economy Test Cycle)

• We obtain the result and the simulation was run for 765 sec
• We observe that for 765 seconds the temperature of the motor rises to 40^oC and for the motor controller, it was about 65 ^oC
• The motor obtains a max torque of about 300Nm and Motor consumed power for about (800- 900) Wh.
• Max's power of about 120A was consumed and min of about 15A.
• The Efficiency of the system was about (80 – 60) percent.
• The total energy consumed for the vehicle was 850-Watt Hour.

EUDC (400 seconds)

EUDC (Extra Urban Drive Cycle)

• The simulation was run for 400 seconds
• We observed a lot of peak overshoot in this simulation. The torque of about 250Nm was observed.
• The motor temperature and controller reached up to 25 ^o The motor consumed about max power of 1400 watt and min power of 200 watts.
• We also observed that efficiency is about 80% to 60% and the energy consumption is a 350-watt hour.

Artemis Motorway(130kmph)

• In this drive cycle the vehicle was run for 130km we observe the motor temperature rise to 60 ^o C and the temperature of the controller rise up to 120 ^o C
• The max torque was 270Nm and a current of 120A was drawn.
• The max power the motor consumed was 1500W and min power of 100W, the efficiency of the system ranges between (80-60) percent
• The total energy consumption for 130km was 2000Wh i.e. 2KW was observed.

The result from the Excel Sheet

• We can create a custom Drive cycle using Excel file by entering the amount of time for the vehicle to be run and the distance to be covered for each time.
• Hence after creating the Excel file we can test the drive cycle and note the performance, in the project the excel file can be run using a spreadsheet and connecting it to the reference speed.
• Excel File Date ⇒ xlsx

Performance for the Drive Cycle is shown below

Energy Consumption	250 Wh
Efficiency	(80-60) %
Max Motor Power consumption	1500 W
Controller Temperature	35o C
Motor Temperature	20 o C
Max Torque	230 Nm
Current	120 A

Conclusion

• With the increase in the number of Rickshaw especially in the city like Mumbai the CO₂ emission has drastically increased.
• Hence there is a need to adopt Electric Rickshaws as these vehicles offer high efficiency and low runtime cost as compared to traditional Rickshaws
• This Battery Powered Rickshaw will be the most popular mode of transport in the coming future hence will be the most affordable and can create a source of income for many people.