Courses/Institutes Maharashtra

Research Article

Registration dates of AIIMS PG 2020 exam postponed to October 16

 14-10-2019

Article written by Team Learning Telescope

14/10/2019

Pune  

 

Registration dates of AIIMS PG 2020 exam postponed to October 16

 

 

 

Registration date extended:  All India Institute of Medical Sciences (AIIMS) has extended the registration dates for the upcoming AlIMS PG 2020 examinations. The eligible candidates who want to apply for this exam can visit the AIIMS official website www.aiimsexam.org.

AIIMS has released the notification regarding the exam on the official website as well. It reads that the candidates who have compulsorily completed an internship or Practical for a period of 12 months are eligible for the All India Institute of Medical Sciences (AIIMS) Post graduation (PG) courses.

The candidates who have completed their practical or Internship before 31st January for January session and 31st July for July session are eligible to apply for this exam. The candidates also need to have Permanent or Provisional registration of the Medical Council of India (MDI) or Dental Council of India (DCI) for their final registration for the AIIMS PG 2020 exam.

The earlier last date for Final Registration along with required details, generation of code and payment completion was October 11, 2019. The new dates for the same are October 16, 2020, until 5 pm. The earlier date to check the application’s status whether it has been accepted or not was October 21, 2019. The new dates for it are October 23, 2019.

The earlier last date for the candidates of Foreign Nationality to obtain the

 

‘No Objection Certificate’ from the Govt of India’s Ministry of Health and Family welfare was October 25, 2019, and its new dates are October 29, 2019, till 5 pm. To submit the sponsored certificate, the last date was October 25, 2019, and its new dates are October 29, 2019.

MHT CET Cut off 2019, 2018 & 2017 - Check Cutoff Here

 12-06-2019

Article written by Team Learning Telescope

Pune

MHT CET Cut off 2019, 2018 & 2017 - Check  Cutoff Here

MHT CET 2019 cut off will be released by the State Common Entrance Test Cell, Maharashtra along with the exam results. The exam conducting authority has released MHT CET results 2019 on June 4. Please note that the MHT CET cut-offs will be declared for All India (AI) as well as Maharashtra candidates. This will further be segregated into categories and institutes. Counseling Process will be done for only those prospects who qualify MHCET cut off.

Factors determining the MHT CET Cutoff 2019

  • Total number of candidates appearing in MHT CET 2019
  • The difficulty level of questions asked in the entrance exam
  • Seat capacity of the course to which admission is sought
  • Previous years’ cutoff trends
  • Category of the candidate

Previous Years' MHT CET cut offs

MHT CET 2019 cut off is yet to be released. Till then, take a look at the cutoffs for previous years'.

Cut Off List for All India Seats of CAP Round I for Admission to First Year of Four Year Full Time Degree Courses in Engineering and Technology for the Academic Year 2018-19

Check Here Cut Off List

Cut Off List for All India Seats of CAP Round-II for Admission to First Year of Four Year Full Time Degree Courses in Engineering and Technology for the Academic Year 2018-19

Check Here Cut Off List

Cut Off List for All India Seats of CAP Round III for Admission to First Year of Four Year Full Time Degree Courses in Engineering and Technology for the Academic Year 2018-19

Check Here Cut Off List

Cut Off List for All India Seats of Additional Round for Government/Govt. Aided Institutes only for Admission to First Year of Four Year Full Time Degree Courses in Engineering and Technology for the Academic Year 2018-19

Check Here Cut Off List

Check Here Cut Off Lists CAP Round-Additional   MH Candidates

MHT CET 2019 (PCM) Percentile Clarification

 11-06-2019

Article written by Team Learning Telescope

Pune

11/6/2019

Since the results for the MHT-CET exam were announced, students and parents are not able to understand the calculations in as percentile score.

Many are of the opinion that students with Physics, Chemistry, Mathematics and Biology(PCMB) group have scored the highest percentile in comparison with Students with only Physics, Chemistry, mathematics(PCM) group.

A student who had won a meritorious award given by state board for class X students in 2017, appeared for her CET in 2019, Suppose x student Scored 150 and got a percentile of 98.2 whereas Y student who was in the PCMB group scored 120 yet got a percentile of 98.5. Students wanting to take admission in engineering are actually getting sidelined by students who were confused between engineering and medicine.

While the results were declared in percentile, in a first in the State, the cell’s office in Colaba received complaints of the results portal being slow and students confused about the new marking system.

Online Exam Pattern-

For the first time this year, the MH-CET exam was conducted online in a span of 10 days, stretching between May 2 and 10. A total of 3, 92,304 aspirants took the entrance exam online this year, as against 4, 19,408 students who had appeared for the exam offline last year.

‘Differences in scores’

Several aspirants complained “There is a difference between the marks that they have scored and the percentile that they have received. The board says that it is not the board's fault and that the rules related to the percentile are clearly mentioned in the MHT-CET brochure released by the cell.

An official from the CET Cell said, “This is the method has been recommended by experts and is tested and accepted. Moreover, other competitive exams such as NEET and JEE use this pattern too. Percentile scores are based on the relative performance of all those who appear for the examination. The marks obtained are transformed into a scale ranging from 0 to 100.”

The official said that the percentile scores indicate the percentage of candidates who have scored below that particular score in the exam. he said, “So, the topper of the exam will get a percentile of 100. Besides this, the marks obtained in between the highest and lowest scores are also converted to appropriate percentiles. This score is calculated up to five decimal places to avoid bunching effect and reduce ties among scores.”

 

How to calculate percentileMHT CET PCM Percentile 2019

Rank= (100-P)*N/100

P= Percentile scored by a student

N=No. of students appearing for the exam

For PCM group, N=276166

For PCB Group, N=281154

The scorecard or result of MHT CET will be set up based on standardization of marks, as the selection test was led in various moves on various dates, the leading specialist will pursue standardization marks criteria to set up the result. it is essentially utilized by the leading specialist to ensure that no competitor is profited or distraught because of the dimension of the trouble of examination in various movements.

The positions will be set up based on normalized marks. Competitors will be granted a percentile score on which positioning will depend. It implies the marks of the applicants are changed over into size from 0 to 100. A normalized score of the hopefuls is the reason for percentile.

The equation to calculate the percentile score is as below-

Percentile Score= 100* No. of competitors in the test with normalized marks less than or equal to the applicant) / Total No. of applicants in the test

An illustration using formula

Overall rank Calculation, Ro= {(100-CET (PCM)percentage of student)/100} * No. of students appeared foe CET+ 1

State level Overall Rank Calculation,

No. of students appeared for CET= 2,76,166

CET (PCM) percentage of a student = 85.5

Therefore, Ro= {(100-85.5)*2,76,166+1

Therefore, Ro= 40.045.07

So, Ro= 40045th Rank at State Level

 

Rank for OBC category of student

ROBC= {(100-85.5)/100*73515+1

ROBC= 107.59

ROBC=10759th

 

 

 

Top Management Colleges in Maharashtra

 14-05-2019

Top Management Colleges in Maharashtra according to MHRD Rating

Sr No

College Name

MHRD rating

Score

Location

Link

1

Indian Institute of Technology Bombay

 

10

 

62.74

 

Mumbai

IITB

2

Indian Institute of Technology Bombay

 

16

 

55.67

 

Mumbai

IITB

3

SVKM`s Narsee Monjee Institute of Management Studies

 

20

 

53.56

 

Mumbai

NMIMS

4

K. J. Somaiya Institute of Management Studies & Research

 

54

 

43.69

 

Mumbai

KJSCE

5

Symbiosis Institute of Business Management

 

20

 

53.56

 

Pune

SIBM

6

Institute of Management and Entrepreneurship Development

 

55

 

43.65

 

Pune

 

IMED

 

7

Institute of Management Technology

 

70

 

40.4

 

Nagpur

 

IMTN

 

Top Engineering Colleges in Maharashtra

 13-05-2019

Top Engineering Colleges in Maharashtra according to MHRD ranking

Sr No

Institute Name

MHRD ranking

Score

Location

Link

1

Indian Institute of Technology Bombay

 

3

84.4

Mumbai

IITB

2

Institute of Chemical Technology

 

12

59.73

Mumbai

ICT

3

Veermata Jijabai Technological Institute

 

105

 

35.64

 

Mumbai

VJIT

4

SVKM`s Narsee Monjee Institute of Management Studies

 

110

 

35.26

 

Mumbai

NMIMS

5

Sardar Patel College of Engineering (SPCE)

114

 

34.79

 

Mumbai

SPIT

6

Ramrao Adik Institute of Technology

 

172

 

31.45

 

Mumbai

RAIT

7

K. J. Somaiya College of Engineering

 

180

 

31.14

 

Mumbai

KJSCE

8

Thakur College of Engineering & Technology

 

193

 

30.51

 

Mumbai

TCET

9

Shri Vile Parle Kelavani Mandal`s Dwarkadas J. Sanghvi College of Engineering

 

195

 

30.47

 

Mumbai

DJSCE

10

College of Engineering

 

49

 

45.89

 

Pune

COEP

11

Bharati Vidyapeeth  Deemed University College of Engineering

 

93

 

36.14

 

Pune

BVUCOEPUNE

12

Bansilal Ramnath Agarwal Charitable Trust`s Vishwakarama Institute of Technology

 

155

 

32.1

 

Pune

VIT

13

Maharshi Karve Stree Shikshan Samstha`s Cummins College of Engineering for Women

 

188

 

30.75

 

Pune

MKSSS

14

Pimpri Chinchwad College of Engineering

 

192

 

30.52

 

Pune

PCCE

15

Army Institute of Technology

 

91

 

36.39

 

Pune

AIT

16

G. H. Raisoni College of Engineering

 

111

 

35.19

 

Nagpur

GHRCE

17

Shri Ramdeobaba College of Engineering and Management

 

112

 

35.02

 

Nagpur

RCOEM

18

The Rashtrasant Tukadoji

Maharaj Nagpur University

 

 

 

122

34.37

 

Nagpur

RTMNU

19

Yeshwantrao Chavan College of Engineering

 

134

 

33.58

 

Nagpur

YCCE

20

Walchand College of Engineering

 

153

 

32.2

 

Sangli

WCOE

 

 

Design And Simulation Of MPPT Algorithm For Solar Energy System Using Simulink Model

 19-04-2019

Published in International Journal of Research in
Engineering and Applied Sciences (IJREAS)

Mr. S. N. Patil shared this article to Learning Telescope

 

Patil Sahebrao N.
patil_sn@rediffmail.com Electrical Engineering Department,
Padmabhooshan Vasantadada Patil Institute
of Technology, Bavdhan, Pune, Maharashtra, India
R. C. Prasad
prasadrcp@rediffmail.com Electrical Engineering Department
College of Military Engineering, Pune, Maharashtra, India


Abstract
In this paper proposes the design modeling and simulation of photovoltaic solar cell model considering the effect of solar irradiations and temperature changes. The PV array is modeled using basic circuit equations. Its voltage current and power voltage characteristics are simulated with different conditions. It is noticed that the output characteristics of PV array are affected by environmental conditions and conversion efficiency is low. Therefore a maximum power point tracking (MPPT) technique is needed to track the peak power to maximize the produced energy. The maximum power point in the power voltage graph is identified by an algorithm called an incremental conductance method. This algorithm will identify the suitable duty cycle ratio in which buck-boost converter should operate to the maximum point. The Simulink model for solar cell, buck-boost converter, MPPT algorithm, and PID controller circuit is modeled and simulated and results are verified.


Keywords: Solar cell model, buck-boost converter, Maximum power point tracking (MPPT), MPPT algorithm, PID controller model.

1.   Introduction
Because of the combustion of fossil fuels global warming caused by environmental problems, the rising prices of crude oils and natural gases. They promote continuous effort to improve the energy system and its efficiency. There is a need to search for abundant and clean energy sources due to the depleted and increasing prices of oil. Solar energy acts as an alternative renewable energy source.
PV module represents the fundamental power conversion unit of a PV generator system. The output characteristics of the PV module depends on the solar insolation, the cell temperature and output voltage of the PV module. Since PV module has nonlinear characteristics, it is necessary to model it for the design and simulation of maximum power point tracking (MPPT) for PV system applications. The mathematical PV models used in computer simulation have been built. [1]- [4]. Developed PV models describe the output characteristics mainly affected by solar insolation, cell temperature, and load voltage. Using the Sim Power System tool in Matlab/Simulink software develops and simulates the different models with different conditions. However, solar energy is a source of energy and its availability varies widely with time. So, it is very necessary to make complete utilization of solar energy in the available time. Many maximum power point tracking algorithms are available for a solar panel in order to produce maximum output. It is very necessary that it is operated consistently at the maximum power point. The Incremental Conductance Method of MPPT is described in this paper.


2.    Modeling of Solar PV Cell
The working condition of the solar cell depends mainly on load and solar insolation. They operate in the open circuit mode and short circuit mode. Based on these characteristics, the output voltage, current and power can be calculated.[3,5]

 

 

 

 

 

 

 

Iph – Photodiode current Vd – Diode voltage
Id – Diode current
n - Diode factor (1 for ideal and >2 for real conditions) Io - Reverse saturation current
T - Temperature for the solar arrays panel in kelvin K – Boltzmann's constant = 1.38 x 10-23 J/K
Q – Electron charge = 1.6 x 10-19C
Rs – Intrinsic series resistance usually in milli-ohms Rsh – Shunt resistance usually in kilo-ohms
The I-V characteristics of a solar cell while neglecting the internal shunt resistance is given by

 

 

 

 

 

In the event that the circuit is shorted indicating that the output voltage is =0. The current through the diode is being omitted. The short-circuit current, Isc = I can be represented by

 

 

Generally, with the relationship that exists between Isc and Iph, the output current is given below. From the relationship, the output current is approximately almost the same as the photocurrent. 

 

 

 

When the circuit is in open-circuit mode, the output current I is =0. At this point, the open-circuit voltage, Voc is calculated.

 

 

 

The output power can be expressed based on the open circuit voltage and short circuit current.

 

 

 

The Pmax relationship is also represented in terms of Vmppt. The Pmax is the maximum output power and Vmppt is the optimal output voltage.[2]

 

Iph – Photodiode current Vd – Diode voltage

 

 

 

 

 

 

 

 

 

 

 

3. Designing of Buck-Boost Converter 


Buck-Boost converter is a combination of a buck and boost converter. A buck-boost converter is a DC-to-DC power converter with an output voltage either greater or smaller than its input voltage. It is a combination of the buck converter topology and a boost converter topology in cascade. The output to input conversion ratio is also a product of ratios in buck converter and the boost converter. The output voltage is controlled by controlling the switch-duty cycle. The term D is the duty ratio and defined as the ratio of the on time of the switch to the total switching period. This shows the output voltage to be higher or lower than the input voltage, based on the duty-ratio D. [5,7]

4.    incremental Conductance Algorithm for MPPT

The output power of the solar PV module changes with change in the direction of the sun, changes in solar insolation level and change in temperature. There is a single maximum power point in the PV characteristics of the PV module for a particular operating condition. It is desired that the PV module operates close to this point, i.e., the output of the PV module approaches near to MPP. The process of operating a PV module at this condition is called a maximum power point tracking (MPPT). Maximization of PV power improves the utilization of the solar PV module.[6].

The most common algorithms the P& O and the incremental conductance method. The conductance method offers the main advantage of providing high efficiency under rapidly changing atmospheric conditions, so it has been employed in the model.

This method is based on the fact that slop of the PV array power curve is zero at the MPP, increasing on the left of the MPP and decreasing on the right-hand side of MPP.

The algorithm starts by obtaining present values of I(k) and V(k) and using former values stored at the end of the preceding cycle, I(k-I) and V (k-I), then judge whether the voltage variable is zero, if it was zero then judge whether the current variable equals zero. Then if the current variable is also zero. It means that PV is operating on the MPP so the conductance should remain the same and the current instruction does not need to change [8].

Two other checks are included to detect whether a control action is required when the array was not operating at the MPP; in this case, the change in the atmospheric Conditions is detected using
(dI ≠0) . Now the control signal adjustment will depend on whether dI is positive or negative if the incremental change in current is positive, the voltage instruction should be increased, otherwise be decreased.
On the other hand, there is a condition where the voltage variable is not zero, another check is carried out by comparing dI/dV with I/V.
According to the result of this check; the control reference signal will be adjusted in order to move the array terminal voltage towards the MPP voltage. At the MPP, no control action is needed, therefore the adjustment stage will be bypassed and the algorithm will update the stored parameters at the end of the cycle as usual. If it was not true then if the conductance variable is more than the negative variable, the voltage instruction should be increased, otherwise be decreased.


 

 

 

 

 

 

   

 

 

 

 

 

5. Matlab Simulink Models
Parameters for solar model: open circuit voltage-21V, short
circuit current-5A, Power -100 W, reference temp-25 and sun illumination S=1 ( 1 sun=1000 w/m^2)
Simulation model of the complete system consisting of Solar PV
model, boost converter, MPPT model and PID controller model is as shown below.

 

 

 

 

 

 

 

Model of PV cell is designed by using a current controlled voltage source. PV cell characteristic equations are written as a function. Solar insolation, ambient temperature, and a number of series connected modules are the input to this function. This function block also takes measured PV cell voltage as input and gives control current signal to controller current source.

 

 

 

 

 

 

 

Algorithm for the incremental conductance MPPT method is implemented in SIMULINK. This algorithm block takes PV voltage and PV current as input and generates a reference voltage command.

 

 

 

 

 

 

Error signal between reference voltage signal generated by MPPT algorithm block and actual voltage is fed to PID controller. The output control signal is compared with a triangular career to generate pulse width modulated signal (PWM). This PWM signal is fed to boost converter.

 

 

 

 

 

 

 


 

 

6.Simulation Results
Based on the algorithm, the simulation was carried using dc-dc
converter system implemented with SimPower Syste
ms toolbox of MATLAB/Simulink model with different conditions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7.Conclusion
In this paper complete model of the PV system containing solar PV cell, DC-DC converter and MPPT control is simulated in SIMULINK. The I-V and P-V characteristics of the solar module are obtained for different values of insolation and temperature. The maximum power is obtained using Incremental Conductance method. It is observed that the characteristics obtained using this method is matching with the theoretical and simulations. Also from this model, the maximum value of voltage Vmp, the maximum value of current Imp and maximum value of power Pmax are obtained. Thus the proposed simulation model of DC-DC converter along with MPPT algorithm can be used as a reference for the implementation of the actual system.

References

[1]    Mohan, Undeland, Robbins, “Power Electronics: Converters, Applications, and Design,” Wiley (Third Edition)
[2]    Muhammad Harunur Rashid, “Power Electronics Circuits, Devices, and Application,” Parentice Hall.
[3]    T.Markvart, “Solar Electricity”, John Wiley & Sons,1994.
[4]    R. Messenger and J. Ventre, Photovoltaic Systems Engineering, CRC Press, 2000, pp.41-51.
[5]    G. R.Walker and P. C. Sernia, “Cascaded DC-DC converter connection of photovoltaic modules,” IEEE Trans Power Electronics., vol. 19, no. 4, pp. 1130–1139, Jul. 2004.
[6]    Roberto F. Coelho, Filipe Cancer, Denizar C. Martins, “A Study of Basic DC-DC Converters Applied in Maximum Power Point Tracking”, Proceedings of IEEE 2009 Conference, ISBN : 978- 1-4244-3370-4, pp. 673-677.
[7]    Doug Mattingly, “Designing Stable Compensation Networks for Single Phase Voltage Mode Buck Regulators”, Intersil, Technical Brief Dec- 2003.
[8]    Tseng, Ching-Jung and Chen,” Novel PWM converters with active snubbers”, IEEE Transactions on Power Electronics, Vol-13, No.- 5, Sept 1998 pp.861-869.
[9]    Xue, Y., Chang, L., Baekhj Kjaer, S., Bordonau, J. and Shimizu, T., “Topologies of single-phase converters for small distributed power generators: an overview,” IEEE Trans. Power Electronics, vol. 19, pp. 1305-1314, Sept. 2004.
[10]    A. Safari, and S. Mekhilef, “Simulation and Hardware Implementation of Incremental Conductance MPPT with Direct Control Method Using Cuk Converter,” IEEE Transactions on Industrial Electronics, vol. 58, pp. 1154 -1161, April 2011.


S.N. Patil was born in Latur, India on 01 Jan 1977. S.N. Patil received B.E. in Electrical, Electronics, and power from SRTM University, Nanded and M.E. Electrical Power System from Govt. College of Engg. Pune and currently he is research scholar of Singhania university and has been working as Asst. Prof. in Electrical Engg. Dept. of Padmabhooshan Vasantdada Patil Institute of Technology, Pune. He has an interest in the Power Electronics and Drives, DSP, Hybrid Energy System.

 

 

Dr. R.C. Prsad is working as Professor in Electrical Engg. Department of College of Military Engineering, Pune. Dr. R.C. Prasad received M.E. Electrical from NIT, Jamshedpur, and Ph.D. in Electrical Engineering from G.B. Pant University of Agri. & Technology, Pantnagar. He has 23 years of teaching and 2 years of Industrial experience. He has an interest in the Power Electronics and Drives, High Voltage Engg., Power quality, and Hybrid Energy System.
 

 

 

Design and Simulation of Buck Boost Controller of Solar Wind Hybrid Energy System

 19-04-2019

Published in International Journal of Latest Trends in Engineering and Technology (IJLTET)


Mr. S. N. Patil shared this article to Learning Telescope

 

Patil S.N.
School of Electrical and Electronics Engg. Singhania University, Rajasthan, India

Dr. R. C. Prasad
Prof. in Electrical Engg. Dept., College of Military Engineering, Pune, Maharashtra, India


Abstract- Because of combustion of fossil fuels global warming caused by environmental problems, the raising prices of crude oils and natural gases. They promote continuous effort to improve energy system and its efficiency. There is a need to search for abundant and clean energy sources due to the depleted and increasing prices of oil. Solar and wind energy acts as an alternative energy source.
The objective is to design and simulate a controller for the unlimited solar power drawn from the sun and produce a higher voltage output through the dc-to-dc converters (Buck-Boost Converter). The Photovoltaic cells have a non-linear V-I characteristics and adapts the Maximum Power Point Tracker (MPPT) to achieve the maximum permissible power obtained. A controller circuit is design to track the maximum power of the photovoltaic at the peak voltage and current level. Dc-to-Dc converters (Buck-Boost Converter) are necessary to produce a higher voltage due to the low input voltage drawn from the photovoltaic cells. The voltage is maintained at a constant voltage at the output load by the switching control circuit. Wind controller circuitry comprises a non-inverting buck and boost converter circuit. The result shows that the model can simulate the photovoltaic models, wind system and track the maximum power which helps to design and improve the power of solar wind energy system.


Keywords: Modeling, Photovoltaic System, Maximum Power Point Tracker, Buck-Boost Converter


I.INTRODUCTION
With the prices of oil at its highest and the increasing demand every year, it is causing environmental concerns which lead to global warming around the world. New energy sources like solar and wind power are readily available and much sought after. They produce clean energy power which does not affect the Ozone layer.
With free solar energy available, cutting down on electrical bills on industrial and home seems a possibility in
the near future as the photovoltaic conversion into electrical energy. Large scale solar energy systems are being tested and might even be implemented in the coming years to cut down the emission of CO2. Demand for photovoltaic energy will increase over the years as the breakthrough in this new technology will sustain it at a lower cost.

 

II.    MODELING OF SOLAR PV CELL
The working condition of the solar cell depends mainly on load and solar isolation. They operate in the open circuit mode and short circuit mode. Based on these characteristics, the output voltage, current and power can be computed.[1

Iph – Photodiode current
Vd – Diode voltage
Id – Diode current
n - Diode factor (1 for ideal and >2 for real conditions)
Io - Reverse saturation current
T - Temperature for the solar arrays panel in kelvin
K – Boltzmann’s constant = 1.38 x 10-23 J/K
Q – Electron charge = 1.6 x 10-19C
Rs – Intrinsic series resistance usually in milli-ohms Rsh – Shunt resistance usually in kilo-ohms
The I-V characteristics of a solar cell while neglecting the internal shunt resistance is given by

 

 

 

In the event that the circuit is shorted indicating that the output voltage is =0. The current through the diode is being omitted. The short-circuit current, Isc = I can be represent by

 

Generally with the relationship that exists between Isc and Iph, the output current is given below. From the relationship, output current is approximately the almost the same as the photocurrent.

 

When the circuit is in open-circuit mode, the output current I is =0. At this point, the open-circuit voltage, Voc is calculated

 

 

 

The output power can be expressed based on the open circuit voltage and short circuit current.

 

 

 

The Pmax relationship is also represented in terms of Vmppt. The Pmax is the maximum output power and Vmppt  is the optimal output voltage.

 

 

 

 

Iph – Photodiode current

Vd – Diode voltage

III.    DC-DC CONVERTERS
Switch mode DC-to-DC converter are normally use to convert the unregulated Direct Current (DC ) input sources into controlled DC output at certain or required voltage level.


A.    Linear

The linear regulators are seen in equipment where the excess heat dissipated and low efficiency is not an issue. The integrated circuit (I.C) is use for voltage regulation. Linear regulator is known as step down regulator because it can only produce output voltage lower than the source voltage. The efficiency can range from 35% to 50%. Linear regulator is cheaper, reliable and much simpler than switching regulators but is mostly suitable for power sensitive analog circuits.


B.    Switch Mode Conversion

In the Switched-mode conversion, the Dc-Dc convert one Dc voltage level by storing the incoming energy temporarily for a time period and releasing the stored energy to the output at a higher voltage. The form of storage may be in either magnetic components such as inductors or transformers and capacitors. It is an efficient method as compare to linear voltage regulators which gives unwanted voltages as heat source. This method is power efficient from 75% up to 98%.


C.    Pulse Width Modulation in switching DC-DC converters


DC-DC converters can be control by the use of the Pulse Width Modulation (PWM) signal at the input gate of the switch. The switch can be of MOSFET or an IGBT type in the circuit. PWM is use in converters to control the period at the pulse to make it switch high or low, by modifying the period of the PWM signal and the time at “on” and “off” position. A continuous triangular waveform with a control signal voltage as shown in figure 2.5 is associated with the controlling of a switch. The constant peak triangular waveforms determine the switching frequency of the cycle and by amplifying the error signal of the converter output and the desired voltage, the control voltage is being output.[5]


IV.    SOLAR CONTROLLER


Buck-Boost converter is combination of a buck and boost converter. It can be an non inverting topology where the output voltage is of opposite polarity as the input. It can also act as a buck converter follow by the boost converter function.
From figure 3, when the switch is in the “on state”, the inductor stored the energy in the magnetic field as it is connected with the source voltage where currents will flow through. The diode is reversed biased and hence no current can flow to the load through the diode. The capacitance will provide current in this “Ton” situation. When the switch is off, inductance is disconnected from the source and there will be no current drop which the inductance will reverse it EMF. A voltage is generated as the diode at this time is forward biased; current will flow in the load and charged up the capacitance.

A.    Boost Converter
 
The converter is made up of an input source voltage, an inductor, a switch, capacitor and the output load. This type of configuration is use to boost up the output voltage with a lower input source. Most of the designs usually specified they require value of input voltage, output voltage and the load current whereas the inductor and ripple current are free parameters. To reduce a ripple, a larger value of inductor should be able to reduce it since it is inversely proportional to the ripple current. Likewise when choosing the inductor, it should ensure the saturation current is greater than the inductor peak current and able to cope with the rms current.

It should be noted a light load for the circuit can go in discontinuous mode. By choosing a large value inductor, the ripple current is two times larger than the minimum load current, the inductor will always operate in continuous mode. [5]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The value of D varies in the range of 0 < D < 1. The lowest output voltage value is when D = 0, which the output voltage equals Vin and when D approaches unity, the output voltage tends to infinity.

B.    Buck Converter

Buck converter components elements are the same as the Boost converter, except the arrangement of the power switch, Inductor and diode are slightly different. Again the operation consists of varying the switching duty cycle of the power switch to obtain desire output voltage. However, this time is to step down from a higher voltage to a lower voltage.
Vout = Vin D
It is clear that the output voltage depends directly on the duty cycle. If the duty cycle is 50%, output voltage will be one half of the input voltage.

 

 

 

 

 

V.    WIND CONTROLLER

Most wind turbine less then 700W in the market comes in either AC or DC output option. The wind controller design here will support both option using the same hardware circuitry by changing certain components and connectors. To support AC output WTG, isolation transformer and bridge rectifier will be used, while these components will be changed in the DC output WTG version. Depending on how strong the wind blows, higher or lower input voltage can be generated from the AC type WTG. Therefore, a non-inverting buck boost topology is implemented here to regulate a constant 42V to the DC bus.[7]
The non-inverting buck-boost converter will be design to operate either in buck or boost mode alone each having their own compensation network and feedback path. Mode selection process is determined by the mode selector circuit, where the rectifier output Vrect is sense and compare with a 42V reference voltage. When Vrect is less than 42 V, circuit will acts Buck Mode. When Vrect is greater than 42 V, circuit will acts Boost Mode.[8]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VII.    CONCLUSION

This paper is presenting the integrated circuit of the simulated photovoltaic cells circuit characteristics, a MPPT controller circuit. This will help us to understand the photovoltaic characteristics, dc-to-dc converters topologies, components calculation and circuit design. A power circuitry is used for DC-DC converter to get the required output. Buck boost converter must control and maintain the voltage at maximum value. And controller will track maximum power. All the hardware design required no programming as it will be done solely based on software stimulation using the PSIM program. The stimulations results reflected that the testing component is capable of producing real-life hardware performance.

REFERENCES

[1]    T.Markvart, “Solar Electricity”, John Wiley & Sons, 1994.
[2]    C.R.sullivan and M.J Powers, “A High Efficiency Maximum Power Point Tracking for Photovoltaic’s arrays in solar- power Race vehicle, IEEE ,1993, pp574-580.
[3]    F.Harashima and H.Inaba, “Microprocessor- controlled SIT Inverter for Solar Energy System”,IEEE Trans. On Industrial Electronics,vo.IE-34, no.1 ,Feb. 1985,pp50-55.
[4]    G. R.Walker and P. C. Sernia, “Cascaded DC-DC converter connection of photovoltaic modules,” IEEE Trans Power Electron., vol. 19, no. 4, pp. 1130–1139, Jul. 2004.
[5]    K. Vijay Kumar reddy And M. Vijaya Kumar, “Modeling and a MPPT method for solar cells,” Journal of Engineering,128- 133,2008,ISSN:1816-949X.
[6]    Ji Chang’ an, Zhang Xiubin, Complementary Wind-Solar Power System Based on Fuzzy Control, Transactions of China Electro technical society, Vol 22, No. 10 2007.
[7]    F.Valenciaga and Paul.P.Puleston, “Supervisor Control for a Stand-Alone Hybrid Power Generation System Using Wind and Photovoltaic Energy,” IEEE Trans. Energy Conversion, vol.20, no.2,pp.398-405,June2005.

 

Research Article on- Designing the Stable Compensation Networks for Buck Boost Converter for Solar Energy System

 17-04-2019

 

Published in International Journal of Science and Modern Engineering (IJISME)
ISSN: 2319-6386, Volume-1, Issue-8, July 2013


Mr. S. N. Patil shared this article to Learning Telescope


Designing the Stable Compensation Networks for Buck-Boost Converter for Solar Energy System
Patil S.N., R. C. Prasad, Member
IEI


Abstract— Because of the combustion of fossil fuels global warming caused by environmental problems, the rising prices of crude oils and natural gases. They promote continuous effort to improve the energy system and its efficiency. There is a need to search for abundant and clean energy sources due to the depleted and increasing prices of oil. Solar energy acts as an alternative renewable energy source.
Photovoltaic cells are used as a renewable energy system. Photovoltaic (PV) cells can be used to generate dc voltages and given to Buck-boost converter. The buck-boost converter output is given to battery to inverter and load.

Buck-boost converter gives a constant output which will control by PWM controller and feedback control system. The feedback control system has a compensation network with different types and parameters. Depending upon parameters and controlling method, we have to decide stability analysis using the Bode Plot. This analysis is carried out by using MATLAB software.


It will be used to design buck-boost converter with different parameters which give constant output. It is helpful for optimizing the feedback-loop design for the best transient response while maintaining a comfortable margin for stability. Design for highest gain and bandwidth feedback loop. It is useful to study different controlling methods and comparison. It is used to select switching frequency, power inductor, selecting capacitors and verify the quality of the output voltage, the harmonic content of the output voltage.


Keywords- Photovoltaic cell model, buck-boost converter, compensation network, Design parameters, stability.

I.    INTRODUCTION
With the prices of oil at its highest and the increasing demand every year, it is causing environmental concerns which lead to global warming around the world. New energy sources like solar and wind power are readily available and much sought after. They produce clean energy power which does not affect the Ozone layer. With free solar energy available, cutting down on electrical bills on industrial and home seems a possibility in the near future as the photovoltaic conversion into electrical energy. Large scale solar energy systems are being tested and might even be implemented in the coming years to cut down the emission of CO2. Demand for photovoltaic energy will increase over the years as the breakthrough in this new technology will sustain it at a lower cost.

Manuscript received on July 2013.
S.N. Patil is Asst. Prof. in Electrical Engg. Dept., P.V.P.I.T. Bavdhan, Pune, India and research scholar Singhania University.
Dr. R. C. Prasad is Professor in Electrical Engg. Dept., College of Military Engineering, Pune, India


In this system, the output of the solar system is variable with respect to different operating condition. So as to get constant output from the solar system we connect the buck-boost converter to battery and battery to inverter and load. For making the constant output, we have to design system parameters and stability circuits. We developed the compensating circuit which gives stable output under different conditions.

I.    MODELING OF SOLAR PV CELL
The working condition of the solar cell depends mainly on load and solar insolation. They operate in the open circuit mode and short circuit mode. Based on these characteristics, the output voltage, current, and power can be computed. [1]

 

 

 

 

 

 

 

Iph – Photodiode current Vd – Diode voltage
Id – Diode current
n - Diode factor (1 for ideal and >2 for real conditions) Io - Reverse saturation current
T - Temperature for the solar arrays panel in
kelvin
K – Boltzmann’s constant = 1.38 x 10Q^(-23) J/K – Electron charge = 1.6 x 10-19C 
Rs    –    Intrinsic    series    resistance    usually in
Milli-ohms
Rsh – Shunt resistance usually in kilo-ohms
The  I-V characteristics of a solar cell while neglecting the internal shunt resistance is given by


In the event that the circuit is shorted indicating that the output voltage is =0. The current through the diode is being omitted. The short-circuit current, Isc = I can be represented by

 

Generally, with the relationship that exists between Isc and Iph, the output current is given below. From the relationship, the output current is approximately almost the same as the photocurrent.

 

When the circuit is in open-circuit mode, the output current I is =0. At this point, the open -circuit voltage, Voc is calculated.

 

The output power can be expressed based on the open circuit voltage and short circuit current.

 

The Pmax relationship is also represented in terms of Vmppt. The Pmax is the maximum output power and Vmppt is the optimal output voltage.[2]

 

 

 

Iph – Photodiode current Vd – Diode voltage

I.    DESIGNING OF BUCK-BOOST CONVERTER TOPOLOGIES
Buck-Boost converter is a combination of a buck and boost converter. It can be an inverting topology where the output voltage is of opposite polarity as the input. It can also act like a buck converter followed by the boost converter function.


 

 

 

 

 

 

 

 

 

 

When the switch is in the “on state”, the inductor stored the energy in the magnetic field as it is connected with the source voltage where currents will flow through. The diode is reversed biased and hence no current can flow to the load through the diode. The capacitance will provide current in this “Ton” situation. When the switch is off, inductance is disconnected from the source and there will be no current drop which the inductance will reverse it EMF. A voltage is generated as the diode at this time is forward biased; current will flow in the load and charged up the capacitance.


The converter is made up of an input source voltage, an inductor, a switch,capacitor and the output load. This type of configuration is use to boost up the output voltage with a lower input source. Most of the designs usually specified they require value of input voltage, output voltage, and the load current whereas the inductor and ripple current are free parameters. To reduce a ripple, a larger value of inductor should be able to reduce it since it is inversely proportional to the ripple current. Likewise when choosing the inductor, it should ensure the saturation current is greater than the inductor peak current and able to cope with the rms current. While designing the buck boost converters following main points are considered [3,4]
1)    
Input voltage to converter
2)    Desired supply output voltage magnitude
3)    DC-DC converter efficiency (Pout / Pin)
4)    Output voltage ripple
5)    Output load transient response(5)
6)    Output load transient response
7)    
Duty cycle of PWM controller


For the design of this buck-boost converter, the output of the converter is designed for 24 V which is given to the Battery. Output voltage=24V


Design of Power Inductor
The power inductor is a very important component within the boost dc-dc design. The inductor value is closely linked with the input voltage, the output voltage, the forward voltage of the diode, the duty cycle, the load current as well as the switching frequency.

 

 

Current rating of an inductor is given by

 

The minimum inductor value can be found.
    Selecting Switching frequency

 

 

 

 

 

 

 

 

Low power loss Mosfet is selected depending on rating.


    PWM Controller
The basic idea is to control the duty cycle of a switch such that a load sees a controllable average voltage. To achieve this, the switching frequency is chosen high enough. With pulse-width modulation control, the regulation of output voltage is achieved by varying the duty cycle of the switch, keeping the frequency of operation constant.
Duty ratio-
D = ton/ (ton + toff)

 

 

 

 

 

 

 

 

 

Power Efficiency-Power Efficiency of    a Buck Converter changes with a change in the load

II.    CONTROLLING METHODS

    Voltage Mode Control
This is a simple method in which there is only one feedback from the output voltage. The input voltage is a main parameter in the loop gain, any changes in the input voltage will alter the gain and will change the dynamics of the system. The voltage mode controller alone cannot correct any disturbances or changes until they are detected at the output. In the voltage based controllers, the compensation loop is difficult to implement.[8]

 

 

 

 

 

 

 

Current Mode Control

In a current-mode control, an additional inner control loop is used. The control voltage directly controls the output inductor current that feeds the output stage and thus the output voltage. The control voltage should act to directly control the average value of the  inductor for a faster response. 

 

 

 

 

 

 

 

 

III.    STABILITY CRITERIA
To accomplish regulation we need to add a feedback loop Also we need to introduce a high DC gain. But with high gain again comes the possibility of instability. These two issues determine the need to have stability criteria 1) feedback compensation design involves selection of a suitable compensation circuit configuration 2) positioning of its poles and zeros to yield an open loop transfer function. Following points to be considered for stability [5,6]
1)    Variations in input voltage do not cause instability.
2)    Allow for variations in the peak-to-peak oscillator voltage.
3)    Error amplifier has sufficient attenuation at the switching frequency.
4)    Mid-frequency gain is greater than zero to prevent a large overshoot at turn-on and during transient conditions.
5)    Error amplifier has the drive capability to drive the feedback network properly.
6)    The phase margin determines the transient response of the output voltage in response to sudden changes in the load and the input voltage
7)    Gain Margin is the difference between unity gain (zero dB) and the actual gain when the phase reaches 180°. The recommended value is -6dB to -12 dB.

5.1 TYPE III COMPENSATION
The Type III compensation circuit has two poles, with two zeros and a pole at its origin providing an integration function for better DC accuracy. Optimal selection of the compensation circuit depends on the power-stage frequency response.[6]

 

 

 

 

 

 


 

There are certain guidelines that can be used for positioning the poles and zeros and for calculating the component values.
1)    Choose a value of R1
2)    Select
a gain (R2 / R1) that will shift the Open Loop Gain up to give the desired bandwidth. Following equation will calculate
a 2 R, that will accomplish this given the system parameters and a chosen R1.

 

3)Calculate C2 by placing the zero at 50% of the output filter double pole Frequency

   

4) Calculate 1 C by placing the first pole at the ESR zero frequency

 

 

   1) Set the second pole at half the switching frequency and also set the second zero at the output filter double pole This combination will yield the following component calculations

 

 

 

 

 

Transfer function for type III compensation is given by

 

 

 

Type III compensator is used to compensate for a second-order LC filter. A traditional type III compensator is sufficient to stabilize the synchronous buck converter for all three modes subsequently being voltage mode control, current mode control.

I.    CALCULATIONS AND RESULTS


According to the above steps if we design the buck-boost converter for the output of 24 V for any input voltage to the converter from the solar panel or system. We write a MATLAB programming for finding the different parameters for type III compensation. [5]
For this consider RL = 5Ω,
ESR = DCR = 1, R1 = 60 kΩ.
Switching frequency =20Khz
From MATLAB programme results are as follows


 

 

 

 

 

 

 

 

 

 

 

For the above values, we can calculate the transfer function for the Buck-Boost converter, compensation network. From transfer function, we plot BODE PLOT for Stability analysis and find out Gain Margin and Phase Margin.

 

 

 

 

 

 

 

 

 

We write programming for plotting the BODE PLOT and results are shown below. Bode Plot of Buck Converter

 

 

 

 

 

 

 

 

Bode Plot of Type III compensation network

    Plot of Total Open Loop Buck Converter

 

 

 

 

 

 

 

 

 

 

 

CONCLUSION: In this paper, we develop a renewable energy system using solar energy as the main source of energy. The output of solar is given to the buck-boost converter. We have calculated different parameters of buck-boost converter such as power inductor, the duty cycle for PWM controller and capacitors. For stability analysis, we designed a feedback control system compensating network with type III and its transfer function gives detailed stability analysis by plotting bode plot. Design for highest gain and bandwidth feedback loop. It is helpful for optimizing the feedback-loop design for the best transient response while maintaining a comfortable margin for stability. A phase margin ranging between 45°and 60° is recommended to avoid instability. The type 3 compensation circuit is used for voltage-mode control because of design flexibility.
REFERENCES
[1]    T.Markvart, “Solar Electricity”, John Wiley & Sons, 1994.
[2]    G. R.Walker and P. C.
Sernia, “Cascaded DC-DC converter connection of photovoltaic modules,” IEEE Trans Power Electron., vol. 19, no. 4, pp. 1130–1139, Jul. 2004.
[3]    Mohan, Undeland, Robbins, “Power Electronics: Converters, Applications, and Design,” Wiley (Third Edition)
[4]    Muhammad Harunur Rashid, “Power Electronics Circuits, Devices, and Application,”
Parentice Hall.
[5]    Michael Day, “Optimizing Low-Power DC/DC Designs –External versus Internal Compensation”, Texas Instruments Incorporated
©2004
[6]    Doug Mattingly, “Designing Stable Compensation Networks for Single Phase Voltage Mode Buck Regulators”, Intersil, Technical Brief Dec-2003.
[7]    Xue, Y., Chang, L.,
Baekhj Kjaer, S., Bordonau, J. and Shimizu, T., “Topologies of single-phase converters for small distributed power generators: an overview,” IEEE Trans. Power Electronics, vol. 19, pp. 1305-1314, Sept. 2004.
[7]    Tseng, Ching-Jung and Chen,” Novel PWM converters with active
snabbers”, IEEE Transactions on Power Electronics, Vol-13, No.-5, sept 1998 pp.861-869.
[8]    Roberto F. Coelho, Filipe
Concer, Denizar C. Martins, “A Study of Basic DC-DC Converters Applied in Maximum Power Point Tracking”, Proceedings of IEEE 2009 Conference, ISBN : 978- 1-4244-3370-4, pp. 673-677.
develop

S.N. Patil was born in Latur ,India on 01 Jan 1977. S.N. Patil received B.E. in Electrical, Electronics, and power from SRTM universityM.E. Electrical Power System from Govt. College of Engg. Pune and currently he is research scholar, Nanded and Singhania university and has been working as Asst. Prof. in Electrical Engg. Dept.of Padmabhooshan Vasantdada Patil Institute of Technology, Pune. He has interest in the Power Electronics and Drives, DSP, Hybrid Energy System.

Hybrid Energy System and Engg., Power quality voltage teaching and 2 years of Industrial experience. He has interest in the Power Electronics and Drives, High years in Electrical Engineering from
G.B. Pant University of Agri. & Technology, Pantnagar. He has 23
PhD and Pune. Dr. R.C. Prasad received M.E. Electrical from NIT, Jamshedpur Engineering ,Dr. R.C. Prasad is working as Professor in Electrical Engg. Department of College of Military

 

 

Research Article on - Battery Monitoring System using Microcontroller

 13-04-2019

Published in International Journal of Computer Applications (0975 – 8887)

Volume 28– No.6, August 2011

Mr. S. N. Patil shared this article to Learning Telescope

 

S.  N. Patil

Asst.Prof., Electrical Engg. Dept., TSSM' s Padmabhooshan Vasantdada Patil Institute of Technology, Pune, India

Sangmeshwar S. Kendre

Lecturer, E&TC Dept., TSSM' s Padmabhooshan Vasantdada Patil Institute of Technology, Pune, India

Dr. R. C. Prasad

Professor, Electrical Engg. Dept., College of Military Engineering, Pune, India

 

 

ABSTRACT
Battery management system (BMS) forms a crucial system component in various applications like electric vehicles (EV), hybrid electric vehicles (HEV), uninterrupted power supplies (UPS), telecommunications and so on. The accuracy of these systems has always been a point of discussion as they generally give an error of maximum 10% considering all the parameters together. In this paper, a system is presented which is developed using low-cost microcontrollers for measurement of electrolyte temperature, electrolyte level and no. of backup hours parameters of lead-acid batteries. Since the batteries, which would be used in the hybrid electric vehicle (HEV), are lead-acid batteries, they will be the focus of this project. While the present prototype system accounts only for measuring backup hours of a car in a stationary as well as in a running mode. With the help of this, we are able to know the battery life span and its efficiency. Data backup is also provided to save all records of the battery.
General Terms
Battery Management System, Electric Vehicles et. al.
Keywords
Batteries; Battery monitoring System; Electric Vehicles; Battery Management System.


1.  INTRODUCTION
With the increasing awareness of global warming around the world, the demand for clean fuel/energy is on the rise and as a result, there is a continuous shift towards the electric vehicles (EVs) and hybrid electric vehicles (HEVs). Battery forms one of the most critical systems in any electric vehicle. Battery performance is influenced by factors such as depth of discharge (DOD), temperature and charging algorithm. EVs and HEVs use battery management system (BMS) to address the implementation of monitoring system parameters such as current, voltage and temperature. This paper attempts to provide a measurement of electrolyte temperature, electrolyte level and no. of backup hours parameters of lead-acid batteries.

2.    GENERAL DESCRIPTION OF THE DESIGNED EMBEDDED SYSTEM
The designed system as shown in figure1.A is developed and it consists of a total of 5 slave modules connected to each 12V battery unit. This unit collects all data regarding battery and sends it serially to master microcontroller.

Slave Unit: To each 12V battery, there is a Slave unit is attached, which is used to measure surrounding temperature, the actual voltage level of a battery. This unit also indicates the low water level in a battery. This data is then sending serially to a Master unit. Block diagram of a slave unit is shown in figure 1.B...


Master Unit: This is the main part of this system. It is used to collect all data coming from Slave via RS232 cable. It also records this data with respect to time with the help of RTC and sends it to an LCD and PC. Hall Effect IC is used to measure current. The block diagram is shown in figure 1.C.

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3.    ALGORITHM
Slave Algorithm:

1.    Start

2.    Read analog voltage, temp.

3.    Convert it into digital data.

4.    If the liquid level is low send an emergency signal to master otherwise go at step 5.

5.    Send data serially to master.

6.    Go at step 2.

Master Algorithm:

1.    Start

2.    Show date and time on LCD.

3.    Convert analog signal from the current sensor into a digital signal.

4.    Store it in memory and display it on LCD in real time.

5.    Display voltage, temperature, float level indication reading from 5 slaves one by one on LCD and store it in memory in real time.

6.    Send data store in memory serially to PC.

7.    Add voltage readings from 5 slaves and display it on LCD and store it in memory in real time.

8.    Go at step 2.


4.    DEVELOPING ENVIRONMENT AND RESULTS
MIDE-51

The microcontrollers program was simulated by using M- IDE software as shown in Fig.2.
MIDE-51 is freeware Integrated Development  Environment (IDE) for MCS-51 microcontroller. The full package already comes with:


Assembler:      ASEM-51      by      W.W.Heinz      (v1.3) C compiler: SDCC: Small Device C Compiler (v2.5.4) Simulator : TS Controls 8051 Emulator v1.0 evaluation (Owner :
http://www.tscontrols.com    was    gone)
Simulator: JSIM-51 Simulator by Jens Altmann (v4.05)

 


 

 

 

 

 

 

 

 

5.  Results Hall Effect Sensor CS3500:

The input given to this sensor is 5V. This sensor is placed in the gap made in the Iron Dust core. Current carrying conductor is passed through the core, the sensor shows the deflection. If the current is in a positive direction, o/p vlg varies in between 2.5 to 5 V. Otherwise, it varies in between 0 to 2.5 V.

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Discharge Characteristics of Battery:

As the battery used for a longer time, battery voltage goes on reducing. This is called as discharge characteristics of the battery. From this, we are able to know the backup given by battery. The following table 2 shows the discharge characteristics.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6.    CONCLUSION:
We have implemented ”Battery Monitoring System” which is capable to measure electrolyte temperature, electrolyte level & no. of backup hours given by battery of the hybrid vehicle and can record all these parameters with respect to time and display it on LCD as well as on the computer. We have tried our level best to make the project as good as possible. The system will help to ensure the efficient working of the battery.

7.    REFERENCES:
[1]    Y.-J. Lee, A. Khaligh, and A. Emadi, “Advanced integrated bidirectional AC/DC and DC/DC converter for plug-in hybrid electric vehicles,” IEEE Trans. Veh. Technol., vol. 58, no. 8, pp. 3970–3980, Oct. 2009.
[2]    H. V. Venkatasetty and Y. U. Jeong, “Recent advances in lithium-ion and lithium-polymer batteries,” in Proc. 17th Annu. Battery Conf. Applications and Advances, Jan. 2002, pp. 173–178.
[3]    Szumanowski and Y. Chang, “Battery management system based on battery nonlinear dynamics modeling,” IEEE Trans. Veh. Technol., vol. 57, no. 3, pp. 1425–1432, May 2008.
[4]    Affanni, A. Bellini, G. Franceschini, P. Guglielmi, and
C. Tassoni, “Battery choice and management for new- generation electric vehicles,” IEEE Trans. Ind. Electron., vol. 52, no. 5, pp. 1343–1349, Oct. 2005.
[5]    J. Bard and L. R. Faulkner, Electrochemical Methods: Fundamentals and Applications, 2nd ed. New York: Wiley, 2001.

Voice Activated Multiprocessor Embedded System To Improve The Control Of A Motorized Wheelchair

 18-03-2019

Published in International Journal of Engineering Science and Technology
Vol. 2(11), 2010, 6812-6818

Mr. S. N. Patil shared this article to Learning Telescope

Mr. SANGMESHWAR S. KENDRE
Lecturer, Electronics & Telecommunication Engineering Department,
TSSM's Padmabhooshan Vasantdada Patil Institute of Technology, Bavdhan, Pune, Maharashtra, India.

Mrs. S. D. JOSHI
Assistant Professor, Electronics & Telecommunication Engineering Department,
TSSM's Padmabhooshan Vasantdada Patil Institute of Technology, Bavdhan, Pune, Maharashtra, India.

Mr. S. N. PATIL
Assistant Professor, Electrical Engineering Department,
TSSM's Padmabhooshan Vasantdada Patil Institute of Technology, Bavdhan, Pune, Maharashtra, India.

Prof. Dr. S. D. APTE
Professor, Electronics & Telecommunication Engineering Department, JSPM's Rajashri Shahu College of Engineering, Pune, Maharashtra, India.

Abstract :
The main idea of this work is to process an analog voice signal. The theme is implemented for controlling the wheelchair by voice through speech processing using Hawkboard (OMAP processor). The adopted model is based on grouping an ARM and a DSP processor for speech enhancement with a voice recognition module for isolated word and speaker dependent. The Texas Instruments OMAP-L138 is integrated in order to enhance the quality of speech signal by reducing noise and connected with the wheelchair for processing of the voice signal. The Hawkboard denoises speech signal and HMC2007 recognizes the commands. It also generates different desired signals according to the spoken words which further used to control the movement of the wheelchair, a vector of information on the context given by a set of sensors for security actions. Six words are recognized which are the start, forward, reverse, left, right, stop. In order to gain in time design, experiments have shown that the best way is to choose a speech recognition kit and to adapt it to the application. The result at the end shows the efficiency of the system.
Keywords: Hawkboard; ARM; OMAP-L138; Digital Signal Processing; speech processing; voice recognition; embedded systems; ultrasonic sensors.

1.    Introduction
In recent work different techniques were introduced to improve the command of an electric wheelchair such as a computer and speech recognition techniques namely: DTW (Dynamic Time Warping) Crossing Zero and HMM (Hidden Markov Model). In a practical sense, speech recognition solves problems, improves productivity, and changes the way we run our lives. Voice control does just about everything a push-button would do. Speech recognition is a very complex problem. It involves many algorithms which require high computational requirements. The variety of applications of automatic speech recognition systems, for human-computer interfaces, telephony, or robotics has driven the research of a large scientific community over the last decades. Automatic speech recognition is now part of many products and applications, in areas ranging from medical transcription to game control, from call center dialogue systems to information retrieval.
Real-time digital signal processing made considerable advances after the introduction of specialized DSP processors. Suitable DSP Starter Kits, with specific DSP processor and related software tools such as assemblers, simulators, and debuggers are available to make system design and application development easier. The chip we recently started to use in our development projects is the OMAP-L138 from Texas Instruments (TI), which contains a fast ARM core, a DSP core, and a graphics accelerator all on one die. 

This new generation of OMAP processors is officially distributed by TI but has a large and growing online community supporting it. As this generation of processors is still fairly new, it is probable.
For our purposes more suitable is a different interesting approach to development boards and follows the idea of keeping the board as simple as possible and supplying only the most needed peripheral hardware mounted on the board itself (Fig.1). Such a system has been developed for the OMAP-L138 by an open source community under the name Hawkboard.

 

  The objective of this design is, therefore, the recognition of isolated words from a limited vocabulary using a speech recognition system from Sunrom Technologies, in the presence of stationary background noise. This application is speaker dependent. To enhance the designed system by avoiding obstacles and secure the wheelchair, a set of ultrasonic sensors for obstacle detection were used.
In the first part of this work, Matlab is extensively used to denoising. First, the words are recorded from microphone using a wave record command in Matlab. The duration of the words if 0.7seconds. Then the noise in words is removed using wavelet denoising method. This wavelet denoising algorithm is implemented on ARM side in Hawkboard.
In this work six words are recognized that are Start, Left, Right, Forward, Reverse and Stop using Speech Recognition System. Hawkboard processes the input voice sample, denoises it and Speech Recognition System decide what is being spoken. After the decision, SRS will generate a predetermined signal for the decoded word. This signal is then applied to Arduino microcontroller for the control of motors of the wheelchair.

 

 

 

 

 

 

 

 

 

Fig. 1. Hawkboard High-Level Block Diagram

2.General Description of the Designed Embedded System
The designed system as shown in figure 2 is developed around the following components:
•Speech Recognition System based on HM2007 special processor, which is the heart of the vocal command system. OMAP-L138 processor and AVR microcontroller
•A set of ultrasonic sensors to avoid collisions
•Interface card to control power circuits of the electric wheelchair

 

 

 

 

 

 

 

 

 

The system model consists of two parts. In the first part, the microphone is connected with a Hawkboard. The Hawkboard is used in the work which has one analog input and one analog output. The microphone is connected with the analog input of the Hawkboard which processes the input voice and generates denoised output. The second part, Arduino Board which is used to control the motion of motor attached with the wheelchair. In order to avoid and maintain a safe distance from obstacles, a set of ultrasonic sensors modules is installed around the wheelchair; the microcontroller selects a module and reads the information from the sensor in order to get more knowledge on the environment.

3.    Practical Details
For best performance, the system gives better results in a quiet environment with the speaker’s mouth in close proximity to the microphone, approximately 4 to 8 cm.

    Hawkboard
Unlike commercial development boards, the Hawkboard has an open source and freely supported operating system coming with a growing repository of working applications. The large and advantageous development community of Hawkboard developers can often solve a problem faster than the technical support of TI can do, although most community efforts are currently still aimed towards the Embedded Linux ARM part of the system.
On top of the low price and large and fast support, the Hawkboard has another advantage: Its physical dimensions are just around 90x100 cm, making it more suitable for portable and student applications.  

 

The USB-powered Hawkboard is a low-cost, fan-less single board computer based on a TI OMAP-L138 dual-core processor that is said to reach laptop-like performance and integrates a 300-MHz ARM926EJ-STM RISC CPU with a high-end 300-MHz C674x VLIW DSP. Additional hardware can easily be connected via USB.

    Speech Recognition System
Speech Recognition System is a component from Sunrom Technologies. The speech recognition system is a completely assembled and easy to use programmable speech recognition circuit. Programmable, in the sense that you train the words (or vocal utterances) you want the circuit to recognize. This board allows you to experiment with many facets of speech recognition technology. It has 8-bit data out which can be interfaced with any microcontroller for further development. Some of the interfacing applications which can be made are controlling home appliances, robotics movements, Speech Assisted technologies, Speech to text translation, and many more. The following are the features of SRS:
•    The self-contained stand-alone speech recognition circuit
•    User programmable
•    Up to 20-word vocabulary of duration two seconds each
•    Multi-lingual
•    Non-volatile memory back up with 3V battery onboard will keep the speech recognition data in memory even after power off
•    Easily interfaced to control external circuits & appliances

 

 

 

 

 

 

 

 

 

 

 

 

The Arduino Duemilanove Board

      

 

 

 

 

 

 

 

 

                             

Fig. 5. Arduino Duemilanove Board

The Arduino is an open-source physical computing platform based on a simple i/o board and a development environment for writing Arduino software. This digital output is then given to Arduino microcontroller. The microcontroller originates the respective signals to control the dc motors which are used to move the wheelchair. If the spoken word is ‘forward’, the wheelchair will move forward, if say ‘stop’ wheelchair will stop, the same respective case with left, right and reverse. So the wheelchair is able to understand six words and will react according to the said words.

    Ultrasonic Sensor modules
In order to avoid and maintain a safe distance from obstacles, a set of ultrasonic sensors modules is installed around the wheelchair; the microcontroller selects a module and reads the information from the sensor in order to get more knowledge on the environment. The module is activated by a brief pulse; it sends a signal with frequency 40 KHz pulses. The pulses reach an obstacle and then come back. The module computes the travel time of the pulses; it then generates a pulse with a width proportional to the distance from the obstacle.

4.    Description of the Application and Operation
The application is based on the development of a vocal command for Wheelchair, by means of simple vocal messages. It, therefore, involves denoising and the recognition of isolated words from a limited vocabulary. The Wheelchair specifications are six commands that are necessary to control the Wheelchair: start, forward movement, backward movement, stop, turn left, turn right. The vocabulary chosen to control the system contains a total of six words. The number of words in the vocabulary was kept to a minimum both to make the application simpler and to make it easier for the user to use.
In order to run a wheelchair safely and comfortably by vocal commands, a set of sensors were added to detect obstacles and avoid misleading. The developed system uses the set of ultrasonic sensor modules, the microphone will be installed.
External noise affects the system since it is by nature in movement within the wheelchair. In designing the application, an account was taken to reduce the affecting noise on the system at various movements. To do so, the external noise was recorded and spectral analysis was performed to study how to limit its effects in the recognition phase.
The vocal command system works in two phases: The training phase and the recognition phase or verification phase. In the training phase, the operator will be asked to pronounce 'say' command words one by one. During this phase, the operator might be asked to repeat a word many times, especially if the word pronunciation is quite different from time to time. Once the 6 words have been used for training the system, the operator can start the second phase. The recognition phase represents the use of the system. In this phase, the system will be in a waiting state, whenever a word is detected.

5.    Developing Environment

    Hawkboard Toolchain
With the Hawkboard every developer faces the opportunity as well as the challenge to write applications for both the ARM Core and the TSMC320C67x+ DSP Core of its OMAP-L138 platform. But before the developer gets a chance to probe the hardware for its potential, he needs a suitable development environment to facilitate his endeavor.
The ARM Core fulfills the role of a general purpose processor running various Embedded Linux Distributions like Angström, Debian, Ubuntu or even Google‘s Android. With every major Linux Distribution comes a repository of open source software, allowing the user to work "out of the box" with familiar applications.
In the context of signal processing, the available Linux tools and APIs may be used for data acquisition and visualization by simply writing an application on a PC and subsequently compiling it for the ARM architecture.
For data visualization and especially debug output we utilize the ARM itself: CodeSourcery, developer of a commercial GNU compiler collection offers with Sourcery G++Lite a free open source C/C++ toolchain for ARM processors, making it relatively easy to write applications for the Linux distribution running on the OMAP-L138. The missing link between the ARM and the DSP-core is supplied by TI's DSP/BIOS-link API in a master-slave constellation. Thus the DSP/BIOS-link API is controlling the DSP from the ARM side, starting it, stopping it and feeding it with the DSP binaries.

    Arduino IDE
The Arduino microcontroller program was simulated by using Arduino IDE software as shown in Fig.6.

 

 

 

 

 

 

 

 

 

 

 

Denoising Result

The sample words are the start, forward, reverse, stop, left and right. Denoising of these words results is shown in Fig.7.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6.    Conclusion
Recent improvements in speech recognition are making lives easier for everybody. Our work is to control Wheelchair by a voice which understands six words (start, forward, reverse, stop, left and right). The words are recognized by using Speech Recognition System. The system uses wavelet denoising and implemented on Hawkboard. Furthermore, Arduino microcontroller is used to control the motion of the Wheelchair. Finally, the wheelchair understands six words and reacts according to the spoken.

References
[1]    Fezari, M.; Khati, A.-E, “New speech processor and ultrasonic sensors based embedded system to improve the control of a motorized wheelchair,” Design and Test Workshop, 2008. IDT 2008. 3rd International 20-22 Dec. 2008 Page(s):345- 349
[2]    Fezari, M.; Khati, A.; Attoui, H., “Embedded system based on multiprocessors to improve the control of a motorized wheelchair” Design & Technology of Integrated Systems in Nanoscale Era, 2009. DTIS '09. 4th International Conference on 6-9 April 2009 Page(s):167 – 170
[3]    http://www.hawkboard.org/.
[4]    http://groups.google.com/group/hawkboard.
[5]    http://www.codesourcery.com. Sourcery G++ light.
[6]    http://elinux.org/Hawkboard.
[7]    Hawkboard User Guide Version1.pdf
[8]    www.arduino.cc/
[9]    en.wikipedia.org/wiki/Arduino
[10]    http://www.sunrom.com/files/DS-HM2007.pdf

 

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