Final Project: Electric Rickshaw modelling

Aim of Project:

Creating a MATLAB model of an electric rickshaw (three-wheel vehicle) with three driving cycles and variation temperature and driver rickshaw for 100Km constant speed driving at 45kmph.

THEORY:

Electric rickshaws (also known as electric tuk-tuks or e-rickshaws or toto or e-tricycles) have been becoming more popular in some cities since 2008 as an alternative to the 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. They are three-wheelers powered by an Electric motor ranging from 650 to 1400 Watts. They are mostly manufactured in India and China, only a few other countries manufacture these vehicles. Battery-run rickshaws could be a low-emitter complimentary transport for the low-income people, who suffer most from a lack of transport facility if introduced systematically according to experts.

Development of the E-rickshaw market in India:

E-Rickshaw's have now transitioned from being a market entrant in the automobile segment of the country to evolve as a leading short-distance transport solution. This segment has gained spurt in the last three years and the growth has been phenomenal. Although, this segment is dominated by a host of unorganized players the established names have also identified the growth beacon and are expected to foray into the segment. One of the first attempts to design electric rickshaws was done by Nimbkar Agricultural Research Institute in the late 1990s.In India, these so-called e-rickshaws are widely spread all over the country, starting to gain popularity around 2011. The design is now much different from cycle rickshaws. Today, e-rickshaws play a vital role in providing livelihood to people in India. Due to their low cost and high efficiency, they are accepted on the Indian streets, but government policies have been threatening the e-rickshaw and banned its use in the capital city Delhi but failed to put them off the streets. E-rickshaws are still rising in number and are widely used in Delhi and other parts of India. In Delhi, as per government official's figures in April 2012, their number was over 100,000.

Specifications and Design:

 

Design and Construction:

These rickshaws have an M.S(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 based on the 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.

Wheel:

In the above body and tire model following blocks are used:

1) Tire (Magic Formula):

Represents the longitudinal behaviour 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.

A is the mechanical rotational conserving port for the wheel axle

H is the mechanical translational conserving port for the wheel hub through which the thrust developed by the tire is applied to the vehicle.

N is a physical signal input port that applies the normal force acting on the tire.

S is a physical signal output port that reports the tire slip.

So this is a car we need 4 wheel and this tire ports connected to the appropriate signal as mention above.

Following parameters considered for tire:

Now we just take the default values to check how they perform but we can take parameters of the currently existing rickshaws.

2) Vehicle Body:

Represents a two-axle vehicle body in longitudinal motion. The block accounts for body mass, aerodynamic drag, road incline, and weight distribution between axles due to acceleration and road profile. The vehicle can have the same or a different number of wheels on each axle. Optionally include pitch and suspension dynamics or additional variable mass and inertia.

H is the mechanical translational conserving port associated with the horizontal motion of the vehicle body. The resulting traction motion developed by tires should be connected to this port.

V, NF, and NR are physical signal output ports for vehicle velocity and front and rear normal wheel forces, respectively.

W and beta are physical signal input ports corresponding to headwind speed and road inclination angle, respectively.

Following parameters considered for vehicle body:

 

 

Gear Box:

The block represents an ideal, non-planetary, fixed gear ratio gearbox. The gearbox is characterized by its only parameter, Gear ratio, which can be positive or negative. Connections S and O are mechanical rotational conserving ports associated with the box input and output shaft, respectively. The gear ratio is determined as the ratio of the input shaft angular velocity to that of the output shaft. The block generates torque in a positive direction if a positive torque is applied to the input shaft and the ratio is assigned a positive value.

Electric system:

Depending upon the tractive force, Environmental conditions, type of vehicle application we choose the motor for the vehicle. For that motor, we will decide the controller

The Electric system Included the Motor, H-Bridge, controlled PWM voltage.

As per our Aim, we using the PM brushed DC motor and for that motor, we used DC to Dc converter which is H-bridge. Following is my Electric model used in this EV model:

To build this model we used the following blocks and parameters changed in it:

1)DC motor:

This block represents the electrical and torque characteristics of a DC 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 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 flows 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.

Following parameters, we used for this Ev model:

Motor Parameters:

Armature Inductance	12e-6
No-load speed	3000 rpm
Rated speed	1500 rpm
Rated load	$1kW$
Rated DC supply voltage	$48V$
Rotor Inertia	$0.01$
Thermal Mass	$20\frac{kJ}{K}$
Initial Temperature	${25}^{0}C$

Mechanical consideration:

Temperature Dependence:

Thermal consideration:

Thermal Port:

The block has an optional thermal port, hidden by default. To expose the thermal port, right-click the block in your model, and then from the context menu select Simscape > Block choices > Show thermal port. This action displays the thermal port H on the block icon and exposes the Temperature Dependence and Thermal Port parameters.

Use the thermal port to simulate the effects of copper resistance losses that convert electrical power to heat. For more information on using thermal ports and on the Temperature Dependence and Thermal Port parameter.

Thermal sensor:

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 the temperature at port B.

DC motor with controller:

 

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.

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.

The following parameters are selected for H-bridge:

Thermal Port:

The block has an optional thermal port, hidden by default. To expose the thermal port, right-click the block in your model, and then from the context menu select Simscape > Block choices > Show thermal port. This action displays the thermal port H on the block icon and adds the Temperature Dependence and Thermal Port parameters. These parameters are described further on this reference page.

When the thermal port is visible:

 

Controlled PWM voltage:

This block creates a Pulse-Width Modulated (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 the block and select Simscape-Block choices to switch between electrical +ref/-ref ports and PS input u 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 is greater 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.

Electrical input ports — The block calculates the duty cycle based on the reference voltage across its ref+ and ref- ports. This modelling variant is the default.

PS input — Specify the duty cycle value directly by using an input physical signal port.

Following parameters used in Controlled PWM voltage:

Controlled voltage source:

The block represents an ideal voltage source that is powerful enough to maintain the specified voltage at its output regardless of the current passing through it. The output voltage is V = Vs, where Vs is the numerical value presented at the physical signal port.

Electrical Reference:

Electrical reference port. A model must contain at least one electrical reference port (electrical ground).

Current sensor:

The 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 conserving electrical ports through which the sensor is inserted into the circuit. The connection I am a physical signal port that outputs the current value.

Battery System and SOC:

To need power for motor and other equipment we give battery pack. This battery pack is decided from a rating of the motor and considering another electric load. So we used a Lithium battery :

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

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

This figure shows the equivalent circuit that the block models.

Mathematical Model:

It consists of the 3 terminals at the input side Ta- Abmiaoint temperature output is the m- Output vector of signals for the battery temperature, state-of-charge, current, voltage, age, maximum capacity, and the ambient temperature and Conserving- + terminal and - terminal.

 

Battery Parameters:

Powergui:

The powergui block allows you to choose one of these methods to solve your circuit:

The powergui block also opens tools for steady-state and simulation results analysis and advanced parameter design.

You need the powergui block to simulate any Simulink model containing Simscape™ Electrical™ Specialized Power Systems blocks. It stores the equivalent Simulink circuit that represents the state-space equations of the model.

When using one powergui block in a model:

(SOC) the state of charge estimator:

This estimator includes the above block which is explained below:

Rate Transition: Handle data transfer between different rates and tasks.

Gain: Element-wise gain (y = K.*u) or matrix gain (y = K*u or y = u*K). Where we used a 60v battery so our formula is like 1/60*3600)

Discrete-time Integrator: Discrete-time integration or accumulation of the input signal.

Scope: to get the result of SOC, Current.

PS Simulink converter: Converts the input Physical Signal to a Simulink output signal.

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

 

 

Inputs:

For the Control and input of the whole EV model, we give input which is Drive cycle, Signal Bilder, and WOT

For the selection of these Inputs, we used multiple switches:

Pass through the input signals corresponding to the truncated value of the first input. The inputs are numbered from top to bottom (or left to right). The first input port is the control port. The other input ports are data ports.

 

MODEL:

 

 

CASE 1: 

When we run the model on default value consider all are which I already uploaded above report.

 

For this, we are using the FTP75 drive cycle as an input:

Run the model for simulation time 2474sec and get the result: