Final Project: Electric Rickshaw modelling

Electric Rickshaw Modelling

Aim:

Design of an electric rickshaw using MATLAB Simulink

Abstract:

In this project we work to create the MATLAB model of the electric rickshaw by doing a PM brushed type DC motor and a suitable Lithium-ion battery for the motor. Before this we will remember what is electric rickshaw how its function and privileges of EV rickshaw then we make an actual EV rickshaw model in Simulink with suitable blocks from the powertrain block set. My main motor is to examine how my RICKSHAW performs for any three standard driving cycles showing energy consumption the temperature rise of motor and controller for vehicle cover around 100KM at constant speed driving 45Kmph.

Objectives:

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 the motor and controller for 100Km constant speed driving at 45Kmph

What is the rickshaw?

A Rickshaw is a kind of vehicle that has two or three wheels. They are usually pulled by a human but there are types that have been changed to be pulled by a bicycle or have their own motor

Introduction to E-Rickshaw

Electric rickshaw (also known as e-rickshaw) have been becoming more popular is some cities since 2008 as an alternative to auto rickshaws and pulled rickshaws because of their low fuel cost, and less human effort compared to pulled rickshaws. They are being widely accepted as an alternative to petrol/diesel/CNG auto rickshaws.

Major parts/components

1. Electric motor: brush less direct current (BLDC)
2. Electronic motor controller
3. Battery: set of 12V deep cycle lead acid/Li-ion batteries
4. Differential: differential is used in e-Rickshaws which is connected to electric motor and rear wheels
5. Front shock absorbers
6. Brakes
7. Miscellaneous parts: speedometer/indicator, front indicator, Head light, charger, left right switch, tier etc.

Working:

The working of E-Rickshaw is based on DC motor, battery & suspension system different from conventional auto rickshaws. It uses a Brush less DC motor ranging from 650-1400Watts with a differential mechanism at rear wheels. The battery used is mostly lead acid/Li-ion battery with a life of 6-12 months. Deep discharge/cycle batteries designed for EVs are mostly used

Procedure:

Power and motor controlled subsystem model (with temperature):

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 assumption about the load the block applies an average voltage to the load that achieves the correct average load current. The simulation mode parameters 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 circulated via one bridge arm in series with the parallel combination of a second bridge arm and a free whiling diode
• Voltage 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 series the temperature of motor
• The block assumes that no electromagnetic energy is lost and hence the back emf and torque constant have numerical value when in SI units motor
• Motor parameters can either be specified directly or derived from the no-load speed and stall torque. If no information is available on armature inductance this parameter can be set to some small non-zero value
• When a Positive current flow from the electrical to-ports a positive torque acts from the mechanical C to R ports. Motor torque direction can be changed by altering the sign of the back emf or torque constants.
• The motor controller will get input from the longitudinal driver. Its takes are to control the speed of the 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 accelator 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 way that H-bridge will generate the required voltage to operate the DC motor for 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 given 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

Controller PWM voltage:

• This block creates a pulse with modulate (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
• The duty cycle is set by the input value Right click block and select simscape block choices to switch between electrical ref/ref ports and ps input to specify the input value
• At time zero the pulse is initialized as high unless the duty cycle is set to zero or the pulse delay time than zero
• The simulation mode can be set to PWM or Averaged. In PWM mode the output is a PWM signal. In Averaged mode the output is constant with a value equal to the averaged PWM signal. Select simulation mode as Averaged

Temperature sensor:

• Temperature sensor is used to measure the temperature of the H-bridge and motor
• The block measures temperature in a thermal network. There is no heat flow through the sensor. The physical signal port T -repots the temperature difference across the sensor.
• The measurement is positive when the temperature at port A is greater than the temperature at port B

Solver configuration:

Defines solver settings to use for simulation

2) vehicle body and tire subsystem mode:

• 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 created a Rear- wheel driven transmission system

• The gear output is given to axels to gear tires in the circuit diagram 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 H-Hub, S- tire slip, N-normal force. As axel connection wind velocity inclination angle. The another constant block where we can assign wind velocity, inclination angle. The tires hub is connected as a common mode 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:

• Vehicle body mass centre of gravity distance values and aerodynamic drag variables are modified
• Pitch dynamic are kept ON with other variable values as default values

Tire:

• Represents the longitudinal behaviour of a highway tire characterize by the tire magic formula. The block is build from tire road interaction (magic formula) and simscape foundation library wheel and axel blocks optionally the effects of tire inertia stiffness and damping can be included
• Connection A is the mechanical rotational conserving port for the wheel axle
• Connections H is the mechanical translation 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 that reports the tire slip optionally expose physical signal port M by setting parameterize by to physical signal magic formula coefficients
• Physical signal port M accepts a four element vector corresponding to the B, C, D, and E magic formula coefficients

Gear:

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

Connection B(base) and F(follower) are mechanical rotational conserving ports specify the rotation between base and follower rotation directions with the output shaft rotates parameter.

Optionally include thermal conserving port H by right clicking on the block and selecting simscape block choices to switch between variants output shaft rotates in the same direction of the input shaft.

The base is connected to the motor shaft and the follower is connected to the rear wheel derive

Vehicle body:

• The block basically represents a two axle vehicle body in longitudinal motion. The block accounts for body mas aerodynamic drag road incline weight distribution between axles due to acceleration road profile
• Here connection H is the mechanical translation 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 angel & W corresponds to the headwind speed (headwind direction opposite to that of the vehicle).

Battery and SOC subsystem model:

Battery:

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 has two stage one is changing and another one is discharging state

The battery is of 75Ah capacity

The Nominal voltage of the battery is 330V

Initial SOC is 100%

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 calculate by 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 multiple 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 controller 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 inputs 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

Power GUI:

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

Longitudinal Driver:

Longitudinal Driver is an inbuild 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 Ve feedback 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 consider and hence a constant block with value 1 is connected
• Info gives the output for the bus signal for different block calculation like the difference in reference vehicle speed and vehicle speed etc
• Acceleration command & Decelcmd correspond to the acceleration and deceleration commands generated respectively and are connected to the corresponding parts of the controlled PWM voltage block
• Here the selected control type is PI accordingly the block implements proportional-integral (PI) control with tracking windup and feed- forward gains

Hole Simulink model:

Initially the current flow 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 follow the given drive cycle reference and run the motor in the require rpm

Then the motor power is transmitted to the wheels of a vehicle through the gearbox and the controller will take the vehicle speed and compare and control