Final Project: Electric Rickshaw modelling

Aim:Design of an Electric using MATLAB Simulink

Abstract:

In this project ,we going to build the MATLAB model of the electric Rickshaw by using a PM brushed type DC motor and a suitable Lithium ion battery for the motor.Before that,we will know about what is ELECTRICAL Rickshaw,how it works and the benefits of EV .Then we make an actual EV rickshaw model in simulink with suitable blocks from the powertrain block set.My main motto is to check "how my Rickshaw performs for any three standard driving cycles showing energy consumption,the temperature rise of motor and controller for vehicle cover arouund 100km at constant speed driving 45kmph.Made a comparision with Mahindra e-Rickshaw and my simulink model.

Objective:

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
• Make an excel sheet of all input and assumed data
• Results: For any three standard driving cycles show energy consumption, temperature rise of motor and controller for 100 km constant speed driving at 45 kmph.

Methodology:

The electric vehicle consists of a battery,motors and controller then it generates propulsion power.

To design any vehicle 1st we have to calculate propulsion power,then the motor is selected.

Lastly based on the motor rating or operate range and no km/charge we want to depend on everything battery capacity and then battery capacity is selected.So the design flow of vehicle engineer has to be like the following:

Identify what amount of propulsion power required.

What is the best suitable motor for that propulsion power.

Then type of battery and range of battery according to the range.

Introduction:

Electric E Rickshaw is also known as elctric tuk-tuk,e-rickshaw and auto which are going more popular after 2018 in Indian market.This E rickshaw is best alternative of petrol /CNG auto rickshaw and human or horse pulled rickshaws because of their low fuel cost.zero emission and less human efforts.

The electrical systems used in Indian version is 48vdc can run 90-100km/full charge,top speed 25km/h and this electric motor power ranging from 650-1400 watts,the battery takes 8-10hrs to become fully charged.Basic seating capacity is driver plus 4 passengers total 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 drive ccycle FTP75.WOT or by using Excel.

The main objective of this project is to obntain speedy by driver ,to estimate the temperature of motor and controller to estimate the state of charge and distance travelled by the vehicle.There is a SOC block that will estimate the state of charge of battery ,distance is calculated by speed and time parameter for all the three Drive cycle.

Design and constructions:

These Rickshaws have an M.S(Mild steel)tabular chasis,consisting of three wheels with a different mechanism at the rear wheels.The nmotor is a brushless DC motor manufactured mostly in India and China.The electrical system used in the Indian version is 49v 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 maintainance,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 consisits of a controller unit.They are sold on the basis of voltage supplied and current output,also the number of Mosfet used.The battery used is mostly a lead acid battery with 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 recuring design difficulty in them.

General detail of E-Rickshaw:

Battery type Lithium ion 330V75Ah

Vehicle kerb weight 260kgs

Load capacity 340kgs

Vehicle speed 7kmph

Driving range 140 km(160Ah)

No of wheels per axel 2

Frontal area 91m

Drag co efficient 5

Wheel radius 306m

Vertical load 3000N

Nominal Voltage 330V

Rated Capacity 75Ah

Initial SOC%100

Internal Resistance 5 ohm

Procedure:

Vehicle Body Subsystem Model:

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 inside the vehicle body and transmission system and in the main design,it is referredn just only as a transmission system.

Here i created a rear wheel drive transmission system.

The gear output is given to axle of rear tires,in the circuit it is shown that gear is connected to rear wheels and front tires is free to rotational motion,thus 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,N-Normal force ,A-axle connection ,wind velocity,inclination angle.The tire 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 the get the distance travelled and state of charge.

Vehicle Body Parameters:

Vehicle body mass,center of gravity distance values and aerodynamics drag variables are modified.

Pitch dynamics are kept ON with other variable values are default values.

Tire:

Represents the longitudinal behavior of a highway tire characterised 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,stifness and damping can be included.

Connection A is the mechanical rotational conserving port for the wheel axle.Connection H is the mechanical transational conserving port for the wheel hub through which the thrust developed by the tire is applied to the vehicle.Connection N is a physical signal input port that applies the normal force acting on the tire.The force is considered positive if it acts downwards.

Connection S is a physical signal output port thta reports to slip and it is set by magic formula coefficients.Physical signal port M accepts a four element vector corresponding to B,C,D and E magic formula co efficients.

Gear:

Represents a fixed ratio gear box.No inertia or compliance is modeled in this block.You can optionally include gear meshing and viscous bearing losses.

Connections B and F are mechanical rotational conserving ports.Specify the relation between base and follower rotation directions with the output shaft rotates parameter.

Optionally include thermal effects and expose thermal conserving port H by right clicking on the block and selecting simscape blocks choice to switch between variants.Output shaft rotates in same direction of input shaft.

Base is connected to the motor shaft and the follower is connected to the rear wheel drive.

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,the connection H is the mechanical transational conserving port hub.NF & NR corresponds to the output ports for normal reactions forces on front axle and rear axle wheels respectively.

The gross weight is given as 600kg.

2.Motors & power converters Subsystem Model (with Temperature Sensors):

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 enabled 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.

If the REV port voltage is greater than the Reverse threshold voltage,then the output voltage polarity is reversed.If the BRK port voltage is greater than the braking threshold voltage,then the output terminals are short circuited via one bridge arm in series with the parallel combination of a second bridge arm and a freewheeling diode.

Voltages at ports PWM,REV and BRK are defined relative to the REF port.If exposing the power supply connections,the block only supports PWM mode.

DC motor:

This block represents the electrical and torque characteristics of a DC motor includes thermal port to sence the temperature of motor

The block assumes that no electromagnetic energy is lost and hence the back emf and torque constants have the same numerical value when in SI units.Motor parameters can either be specified directly if no information is available on armature inductance,this parameter can be set to some small non zer value.

When a positive current flow from the electrical + to - ports,a positive torque acts from the mechanical C to R ports.

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.Majorily motor controlled we designed had two main parts named PWM voltage generated and H-bridge.

PWM voltage block negative reference and REF are grounded and REF of H bridge respectively.H bridge is a motor controller thta has IGBT components aligned in the shape of H.

Controlled PWM voltage:

This block creates a PWM voltage across the PWM and REF ports.The output voltage is zero when the pulse is low,and is equal to the output voltage amplitude parameter when high.

Duty cycle is set by the inputvalue

At time zero,the pulse is initialised as high unless the duty cycle is set to zero or the pulse delay time is greater than zero.

The simulation mode can be set to PWM or averaged.

Temperature Sensor:

Temperature Sensor is used to measure the temperature of H-bridge and motor.

This block measures temperature in a thermal network.There is no heat flow in the sensor.

The temperature is positive when port A is greater than port B.

Solver configuration:

Define solver settings to user for simulation.

3.Battery And SOC Subsystem model:

Battery:

The battery is required to power the controller and motor.The controller uses the battery power according to procedure the input given by the motor to obtain maximum speed.The battery is also used to power every electrical componenet in the vehicle.

The battery block implements a generic dynamic model that reperesents most popular types of rechargable batteries.

The battery has two stage i.e charging and discharging state.The battery is of 75Ah capacity.

The nominal voltage of battery is 330V

Initial SOC of 100%

The battery as a series internal resistance plus a charge dependent voltage source defined by:

V=(Vnom*SOC)/(1-B.(1-SOC))

when SOC is the state of charge and Vnom is the nominal voltage.Coefficient beta is calculated to satisfy a user defined data point [AH1,V1}

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 the giving it to the rate transition and then to gain where 1/(nominal 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 percentage of battery.

The majority of blocks are simscape blocks where 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 teh 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.

Bus Selector:

The bus selector block outputs the signal you select from the input bus.the block can output the selected elements seperately or in new virtual bus.

Power GUI:

Continuous ,which uses a variable step solver from simulink.

Discretization of the electricsal system for a solution at fixed time steps.

Continuous or discrete phasor solution.

Longitudinal Driver:

It is a parametric longitudinal speed tracking controller for generating normalised Acceleration and braking commands based on refrerence 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 velocity with the reference velocity,the driver block generates acceleration and braking signals in order to minimise the error between the two connected velocities.

Grade corresponding to the grade angle.For this simulation ,no inclination is considered and hence,a constant block with value 1 is connected.

Info gives the output for the bus signal for different block calculations like differnce in reference vehicle speed and vehicle speed.

Refernce Velocity (Drive cycle):

Drive cycle is assumed as the drivers input of a vehicle it replaced how a driver will drive a vehicle.Here i have used three drive cycles which used to test the vehicle performances.These drive cycle will have high speed,low speed,bttraking conditions it.

There are different drive cycles like WOT,FP75 etc.Here in this model i have used FTP 75,WOT & manually prepared in excel drive cycle source.

FTP 75:

Generates a standard or user specified longitudinal drive cycle.The block output is teh vehicle longitudinal speed.You can import drive cycles from:

Ptredifined source

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 specified speed and time tolerances.

Wide Open Throttle:

Manually prepared drive cycle:

Simulink Model:

Initially current flows to DC motor from the battery through the DC-DC power converter to drive the motor.The required voltage will be controlled in the controller.the controller will follw the given drive cycle reference and run the motor in the required rpm.

Then the motor power is transmitted to the wheels of a vehicle through the gear box,and the controller will the vehicle speed and take and compare and controlled.

Outputs:

For FTP75 Drive cycle

By running FTP75 Drive cycle the distance travelled is 1.532 km for 1000sec

The actual speed is approximate followed the 80% of reference drive cycle.

The temperature of motor is increased to 315 degree C.

The temperature of controller is approximately 600 degree C.

The SOC of the battery is reduced to 81%

For WOT Drive cycle

By running WOT Drive cycle the distance travelled is 0.1957km for 1000sec

The actual speed is approximate followed the 85% of reference drive cycle.

The temperature of motor is increased to 315 degree C.

The temperature of controller is approximately 1010 degree C.

The SOC of the battery is reduced to 95%

For Manually prepared drive cycle:

By running Manually prepared Drive cycle the distance travelled is 0.4287km for 1000sec

The actual speed is approximate followed the 80% of reference drive cycle.

The temperature of motor is increased to 315 degree C.

The temperature of controller is approximately 1090 degree C.

The SOC of the battery is reduced to 96.5%

Conclusion:

Since i have modelled a Electric vehicle Rickshaw and discussed the results of SOC,Energy consumption,motor temperature,controller temperature,reference speed with vehicle speed with all these we can compare the graphs which we seen above.