Final Project: Electric Rickshaw modelling

# ABSTRACT

In this project, we work to create the MATLAB model of the Electric Rikshaw by using a PM brushed type DC motor and a suitable Lithium-Ion battery for the motor. Before this, we will remember what is , how it's functioning and the privileges of the Electric Rikshaw.Then we make an actual EV RICKHAEW model in SIMULINK with suitable blocks from the powertrain block set. My main motto is to examine "how my Rikshaw performs for any three standard driving cycles showing energy consumption, the temperature rise of motor and controller for vehicle cover around 100 km at constant speed driving 45 kmph. Made a comparison with Mahindra e-Rickshaw and my Simulink model.

# AIM

Create a detailed MATLAB model of an electric rickshaw.

# OBJECTIVE

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

Rear wheels driven by PM brushed type motor

Assume efficiency points of motor controller and motor

Make an excel sheet of all input and assumed data

Results: For any three standard driving cycles show energy consumption, the temperature rise of motor and controller for 100 km constant speed driving at 45 kmph.

* So the Design flow of the vehicle engineers has to be like the following:

1. Identify what amount of propulsion power is required.
2. What is the best suitable motor for that propulsion power?
3. Then type of battery and range of battery according to the range.

# INTRODUCTION

• Electric E-Rickshaw is also known as an electric tuk-tuk, e-rickshaw and auto which are going more popular after 2018 in the Indian market. This E-rickshaw is the best alternative to petrol/CNG auto-rickshaw and human or horse-pulled rickshaws because of their low fuel cost, zero emissions and less human efforts.
• The electrical system used in the Indian version is 48VDC can run 90-100 km/full charge, top speed 25 km/hour and this electric motor power ranging from 650-1400 Watts: the battery takes 8-10 hrs to become fully charged. Basic seating capacity is driver plus 4 passengers total of 5 persons.
• Here basically, e-rickshaw is designed in CREO and MATLAB Simulink In the designed electric rickshaw main blocks are battery, drive cycle, controlled, DC Motor, Vehicle body and transmission system. Drive cycle is the input of human effort that how he is going to drive his actual cycle We can use dive cycle like FTP75, WOT or by using Excel
• The main objective of this project is to obtain speed by the driver, to estimate the temperature of the motor and controller, to estimate the state of charge (SOC) and distance travel by the vehicle. There is a SOC block that will estimate the state of charge of the battery, distance is calculated by speed and time parameter for all the three Drive cycle

* Design and Construction:

These rickshaws have an MS(Mild Steel) tubular chassis consisting of three wheels with a differential mechanism at the rear wheels. The motor is a brushless DC motor manufactured mostly in India and China. The electrical system used in the Indian version is 48V and in Bangladesh is 60V The body design from the most popular Chinese version is of very thin iron or aluminium sheets. Vehicles made in fibre are also popular because of their strength and durability, resulting in low maintenance, especially in India.

• The body design is varied from load carriers, passenger vehicles with no roof, to full body with windshield for drivers comfort. It consists of a controller unit. They are sold on the basis of voltage supplied and current output, also the number of MOSFET (metal oxide field-effect transistors) used. The battery used is mostly a lead-acid battery with a life of 6-12 months. Deep cycle batteries designed for electric vehicles are rarely used. The weight of the electric car has also been a recurring design difficulty in them.

# THEORY

Battery:

• Most electric vehicles use lithium-ion batteries (Li-Ions or LIBs). Lithium-ion batteries have a higher energy density, longer life span and higher power density than most other practical batteries. Complicating factors include safety, durability, thermal breakdown and cost. Li-ion batteries should be used within the safe temperature and voltage ranges in order to operate safely and efficiently.
• Increasing the battery's lifespan decreases effective costs. One technique is to operate a subset of the battery cells at a time and switching these subsets.

• In the past, nickel-metal hydride battery batteries were used in some electric cars, such as those made by General Motors. These battery types are considered outdated due to their tendencies to self-discharge in the heat. Furthermore, a patent for this type of battery was held by Chevron, which created a problem for their widespread development. These factors, coupled with their high cost, have led to lithium-ion batteries leading as the predominant battery for EVs.
• The prices of lithium-ion batteries are constantly decreasing, contributing to a reduction in the price of electric vehicles.

Electrical Motor:

• The power of a vehicle's electric motor, as in other machines, is measured in kilowatts (kW). Electric motors can deliver their maximum torque over a wide RPM range.
• This means that the performance of a vehicle with a 100 kW electric motor exceeds that of a vehicle with a 100 kW internal combustion engine, which can only deliver its maximum torque within a limited range of engine speed.
• The efficiency of charging varies considerably depending on the type of charger, and energy is lost during the process of converting the electrical energy to mechanical energy.

• Usually, direct current (DC) electricity is fed into a DC/AC inverter where it is converted to alternating current (AC) electricity and this AC electricity is connected to a 3-phase AC motor.
• For electric trains, forklift trucks, and some electric cars, DC motors are often used. In some cases, universal motors are used, and then AC or DC may be employed. In recent production vehicles, various motor types have been implemented; for instance, induction motors within Tesla Motor vehicles and permanent magnet machines in the Nissan Leaf and Chevrolet Bolt

Motor Controller:

• The motor controller of an electric car administers its complete operation and the distribution of its power at any given moment. It acts as a floodgate between the motor and batteries.
• It helps monitor and regulates all key performance indications such as the vehicle's operator, motor, battery, and accelerator pedal. It has a microprocessor that can limit or redirect current.
• It is used to either improve the mechanical performance of the car or suit the operator's driving style. There are also more refined controllers which are capable of greater accuracy and thus, higher efficiency.

# SIMULATION

General detail of E-Rickshaw

Battery Type Lithium-ion 330 V 75

Vehicle kerb weight 260 kgs# Load capacity 340 kgs

Vehicle speed 7 kmph

Driving range 140 km (160 Ah)

No. of wheels per axel 2

Frontal Area 91m

Drag coefficient 5 Wheel radius 306m

Vertical load 3000 N

Nominal Voltage 330 V

Rated capacity 75Ah

Initial SOC 100 %

Internal Resistance 5 ohm

The electric vehicle is constructed in a manner of four step-by-step processes,so to design of the EV model always starts within the order:

1) construction of vehicle body design

2)Selecting the motor

3)Suitable control unit for motor

4)Source of energy for motors

1) Construction of vehicle body design

• Motor will produce the rotational output which will give to the vehicle body and transmission system. The rotational output is taken by the gear system here to maintain the constant speed throughout the transmission without any loss in speed from the motor to tires.
• Below is a diagram that is how it is inside the vehicle body and transmission system and in the main design, it is referred just only as a transmission system. Here I created a Rear-wheel drive transmission system.

• The gear output is given to axels of Rear tires in the circuit it is shown that gear is connected to Rear wheels and the front tire is free to rotational motion, thus the vehicle moves forward. N is the normal force caused by the tires and it is given to the vehicle body normal force port.
• The vehicle body has an H-Hub, S- Tire slip, and N-Normal force. As axel connection, wind velocity, and inclination angle. The tires hub is connected as a common node to the vehicle body.
• The vehicle body wind velocity is connected to a constant block and the beta-inclination angle is connected to another constant block where we can assign wind velocity and inclination angle as per requirement. Velocity is the output port where we can get at which speed the vehicle is moving. The velocity is taken out to get the distance travelled and state of charge

* Vehicle Body Parameters

Input Ports:

W=Wind Velocity in m/s

beta=Grade angle in radians

Output Ports:

V=Velocity in m/s

NR=Normal force on Rear Axle (N)

NF=Normal Force on Front Axle (N)

• Vehicle body mass, Centre of gravity distance values and aerodynamic drag variables are modified.
• Pitch dynamics are kept ON with other variable values as default values.
• Represents the longitudinal behavior of a highway tire characterized by the tire Magic Formula. The block is built from Tire-Road Interaction (Magic Formula) and Simscape Foundation Library Wheel and Axle blocks. Optionally, the effects of tire inertia, stiffness and damping can be included.
• Represents a two-axle vehicle body in motion.
• Accounts for body mass, and aerodynamic drag. grade, externally defined mass and centre of gravity of the vehicle body.
• 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, connection H is the mechanical translational conserving port hub.
• NF & NR correspond to the output ports for normal reaction forces on the 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 the vehicle).

* Tire:

• The vehicle is assumed to be front axle is driven (4 wheels- 2 on each axle).
• The wheels are modeled using simple Tire (Magic formula) Simulink blocks.
• The block can model tire dynamics under constant or variable contact surface conditions.
• Input Port: N=Normal force acting on the tire, positive when force is acting downwards/towards the contact surface.
• Output Port: S=Slip value is relative to tire and surface of contact.
• Conserving Ports: H=represents wheel hub which transmits thrust generated by the wheel to the body of the vehicle.
• A=represents the axle on which the tires are mounted.

• The tires are parameterized by Peak longitudinal force and corresponding slip
• The other block parameters such as rated vertical load, peak longitudinal force at rated load and slip at peak force at rated load are kept with their default values.

Gear:

• A simple gear block is used to connect the motor to the rear axle of the vehicle.
• It represents the gearbox that connects the input shaft to the base gear and output from the follower gear.

• Conserving Ports: B=port associated with an input shaft (motor shaft)

F=port associated with the output shaft (axle/ differential)

• Gear ratio and output direction are modified. Meshing loss is kept constant and gear is having a constant efficiency throughout the simulation.
• Viscous losses and faults are kept at default conditions
• Here teeth Ratio given is 9,in same direction of the shaft

2) Selecting the motor

The Motor controller will get input from the longitudinal driver. Its tasks are to control the speed of the motor and drive according to the input of the driver.

• Majorly motor controlled we designed had two main parts named PWM voltage generator and H-Bridge Input 1 is getting from the acceleration of a longitudinal driver and it is given to a controlled voltage source block where it is input to the controlled PWM voltage will generate a PWM signal in such a way that H-bridge will generate the required voltage to operate the DC motor for the given driver input
• PWM voltage block negative reference and REF are grounded and REF of H bridge respectively. H-bridge is a motor controller that has IGBT components aligned in the shape of H and will operate only two at a time respectively to the input of the signal from the PWM block.
• When deceleration occurs this H-bridge will give an output from the positive and negative terminals of it. These negative & positive terminals are later connected to the DC motor and battery. All these components are the simscape electrical components so they need a connection to the solver configuration block which helps to solve the simulation.

* D.C Motor:

This is the DC Motor that would give rotational power to the wheels and become the sole power generation source.

The DC Motors terminals are connected as mentioned below.

+ =Electrical signal to the motor Positive Terminal

- =Electrical signal to the motor Negative Terminal

R=Casing of the Motor connected with the Mechanical Rotational Reference Block

C=Rotor Case connected to the Mechanical Rotational reference

The parameter considered is, The Armature inductance is as default, varied the changes in the No-Load Speed 6000 rpm, the rated speed 4000 rpm, the Rated Load at 15kW, and the Rated DC Supply Voltage 300 V. All other parameters are as default.

* Temperature Sensor

• Temperature Sensor is used to measure the temperature of the H-Bridge and Motor.

• This block measures temperature in a thermal network. There is no heat flow through the sensor. The physical signal port T reports the temperature difference across the sensor.
• The measurement is positive when the temperature at port A is greater than temperature at port B.

* H Bridge

• This block represents an H-bridge motor drive. The block can be driven by the Controlled PWM Voltage block in PWM or Averaged mode.
• In PWM mode, the motor is powered if the PWM port voltage is above the Enable threshold voltage in Averaged mode.
• The PWM port voltage divided by the PWM signal amplitude parameter defines the ratio of the on-time to the PWM period.
• Using this ratio and assumptions about the load, the block applies an average voltage to the load that achieves the correct average load current.
• The Simulation mode parameter value must be the same for the Controlled PWM Voltage and H Bridge blocks.

The H-Bridge helps in controlling the power that is input according to the requirement. The output provided is converted voltage as per the controlled parameters.

* Controlled PWM Voltage:

The Controlled PWM Voltage Block helps in keeping the Modulated Pulses as per the required pulses. So that the operations happen smoothly and higher variations are not observed.

The Ports are connected as follows.

PWM=PWM connected directly to the H-Block

REF=REF connected directly to the H-Block

ref+ = Reference Positive connected with Driver Model ith the Acceleration Commands from the

ref- =Reference Negative connected with the Deceleration Commands from the Driver Model

Note: The parameters are set as default.

3)Battery and SOC System

* Battery

Implements a generic battery model for most popular battery types. Temperature and ageing (due to cycling) effects can be specified for Lithium-Ion battery type.

• The battery is required to power the controller and motor. The controller uses the battery power according to produce the input given by the motor to obtain maximum speed.
• The battery is also used to power every electrical component in the vehicle.
• The Battery block implements a generic dynamic model that represents the most popular types of rechargeable batteries.

The battery has two-stage one is charging and another one is discharging state.

The battery is of 75Ah capacity.

The Nominal voltage of the battery is 330 V

Initial SoC is 100%

The battery as a series internal resistance plus a charge-dependent voltage source

defined by:

where SoC is the state of charge and Vnom is the nominal voltage.

Coefficient beta is calculated to satisfy a user-defined data point [AH1,VI].

• The battery has a positive and negative terminal which is given the voltage-controlled source where the battery consumption is controlled by the motor controller and then it is given to the SOC block

* Battery State of Charge:

• SoC is the percentage or level of battery presents after certain travel or consumption of battery charge by the vehicle.
• In the designed vehicle battery charge or SOC is calculated by giving it to the rate transition and then to gain where 1/inominal battery capacity) then to a discrete-time integrator and it will get minus from the 1 as it is considered a 100% of battery and it is multiplied with 100 to get a percentage of battery.
• The majority of blocks are simscape blocks were physical to Simulink converter is used to convert the physical signal from simscape block to Simulink signal

* 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.
• We can initialize the Controlled Current Source block with a specific AC or DC current. if we 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
• Double click controlled current source and from the drop-down menu of measurement select current.
• Signal output will connect with scope by adding the current signal to it. (+) the terminal will connect with the battery (-) terminal.

* BUS Selector

• The Bus Selector block outputs the signals you select from the input bus The block can output the selected elements separately or in a new virtual bus.
• Here just we have mange the output and connect it with different Scope Block.

* PowerGUI

• The powerful block allows us to choose one of these methods to solve.
• Continuous, which uses a variable-step solver from Simulink your circuit
• Discretization of the electrical system for a solution at fixed time steps. Continuous or discrete phasor solution
• The powerful block also opens tools for steady-state and simulation results analysis and for advanced parameter design

4)Source of energy for motors

* Longitudinal Driver:

• The longitudinal Driver is an inbuilt block provided by the powertrain blocks.
• It is a parametric longitudinal speed tracking controller for generating normalized Acceleration and Braking commands based on reference and feedback velocities,
• The 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 minimise 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 the 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 Here, the selected control type is Pl. Accordingly, the block implements proportional-integral (PI) control with tracking windup and feed-forward gains.

* Reference Velocity (Drive Cycle):

1) FTP75 (2474 seconds)

• The Drive Cycle Source block is used to provide the reference speed for the simulation.
• It generates a standard or user-specified longitudinal drive cycle.

Generates a standard or user-specified longitudinal drive cycle.

The block output is the vehicle longitudinal speed.

we can import drive cycles from:

# Predefined sources

# Workspace variables, including arrays and time series objects

# mat, Xls, xlsx, or txt files

Use the fault tracking parameters to identify drive cycle faults within the specified speed and time tolerances

2) Wide Open Throttle (WOT):

Wide-open throttle or wide-open throttle (WOT), also called full throttle, is the fully opened state of throttle on an engine (internal combustion engine or steam engine)

)3 Manually prepared Drive Cycle:

All 3 Drive cycles are controlled by the controller provided above by constant through Multi-part switch.

# SIMULATION RESULTS

Case1

1) For FTP75 Drive Cycle:

• By running the Vehicle with F1P75 Drive cycle for 2474 see the distance travelled is 3.528 km
• The actual Speed is approximately followed the 80% of reference Drive cycle.
• Initially the battery is 100% charged, after travelling this much distance its battery state is about 98 percentage
• Its clear from the graph that battery is discharged during acceleration and charged during decceleration.
• The Temperature of Motor is increased to 415°C.
• The Temperature of Controller is 500°C.

2) WOT Drive cycle

• By running the Vehicle with WOT Drive cycle for 30 sec. the distance travelled is 0.0886km
• The actual Speed is approximately followed the 80% of the reference Drive cycle.
• The SoC% of the battery is reduced to 99.8% at 20 th sec and after that the battery get charged by back EMF.
• Its clear from the graph that battery is discharged during acceleration and charged during deceleration.
• The Temperature of the Motor is increased to 305°C.
• The Temperature of the Controller is 480°C.

3) For Manually prepared Drive Cycle:

• To increase the speed of the vehicle, the output voltage amplitude is applied to 400 V. . By running the Vehicle with Manually prepared Drive cycle for 120 sec the distance travelled is 0.1744km
• The actual path of the speed is approximately followed the of reference Drive cycle as above.
• The SoC% of the battery is reduced to = 99.2 %.
• The Temperature of Motor is increased to 305°C.
• The Temperature of Controller is 480°C.

Case 2 (100 km constant speed driving at 45 kmph)

Speed=Distance/Time

Time=Distance/speed

t=(100/45)*3600=8000s

• So we can give WOT drive cycle for 8002 sec, for 45kmph speed
• we can use PID Controller block from the library instead of the driver block, There we can tune the PID values in the correct manner.
• And we can change the motor battery parameters
• Otherwise change the PI Parameter values in the Longitudinal driver, so that we can make the vehicle speed nearly equal to the reference speed.

# CONCLUSION

The temperature of Motor and controller is controlled to achieve vehicle speed is near to reference speeds. Since I haven't used any cooling system in the model. In the real-time application, the motor temperature is less than 100 C. In the real-time application, the motor, battery & controller temperature is controlled by air cooling. Hence, the temperature of these components is not increased to this extent.

Created a MATLAB model of an Electric Rickshaw (three-wheel passenger vehicle) by using Li-ion battery, PM Brushed DC Motor. Determined the variations of Temperature of Motor and controller, SoC% and Energy consumed by the by vehicle for all the three Reference Drive cycles (.e: FTP75, WOT, Manually prepared). This Battery powered Rickshaw will be the most popular mode of transport in the future.