industry speed-control final

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Methods of Controlling DC motors and Servo MotorsIndustrial Electronics

DEPARMTENT OF ELECTRONIC ENGINEERING FACULTY OF INFORMATION AND COMMUNICATION TEHCNOLOGY

BALOCHISTAN UNIVERSITY OF INFORMATION TECHNOLOGY ENGINEERING AND MANAGEMENT SCIENCES

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BALOCHISTAN UNIVERSITY OF INFORMATION TECHNOLOGY ENGINEERING AND MANAGEMENT SCIENCESNAME DESIGNATION DEPARTMENT

ENGR .JUNAID ASSISTANT PROFESSOR DEPARMTENT OF ELECTRONIC ENGINEERING

NAME DESIGNATION ROLE DEPARTMENT

MUHAMMAD SAMAD KHAN UG-STUDENT 23846 DEPARMTENT OF ELECTRONIC ENGINEERING

HUMNA ZAHID UG-STUDENT 25308 DEPARMTENT OF ELECTRONIC ENGINEERING

TALAL AHMED KAKAR UG-STUDENT 25149 DEPARMTENT OF ELECTRONIC ENGINEERING

MUHAMMAD WASIM UG-STUDENT 25367 DEPARMTENT OF ELECTRONIC ENGINEERING

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SEQUENCE OF PRESENTATIONSR. NO. SECTION TITLE

1. Motivation

2. Introduction

3. Methodology

a. Methods of controlling DC motors.

b. Methods of controlling servo motors.

4. Results.

5. References.

1. Motivation .

Energy conservation and control power are two main important factors for adjustable speed.

Power saving can be achieved by controlling speed of pumps, fans, motors, etc. power supply is very important to operate direct current (dc) motor.

In various applications, Accurate, precise and controlled angular movements plays vital role

Industrial demands are increasing day by day automation provide best quality products, raise in yield and cost reduction automation is one of the best application of controlling speed of motor.

In vehicle industries, robots performing welding, coloring etc. must have precise and accurate angular motions

Power supply and speed have direct relation with each other if we don’t know how to control the speed of motor it might create severe problems.

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2. Introduction



Dc motors [1,4] converts direct current into mechanical energy. it consist of field winding, commutator, brushes, poles, stator, rotor

and yoke. construction of dc motor

Principle of dc motor. Dc motor work on the principle of electromagnetic induction. States that when a current carrying conductor is placed in a

magnetic field, it experiences a mechanical force.

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3. Methodology .



a. Methods for controlling speed of DC motor.

The speed of a DC motor can be controlled in four different ways. Flux control method. Armature control method. Voltage control method. Pulse width modulation.

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I. Flux control method.[2]

Speed is controlled via controlling the flux generated by field winding

Since flux generates due to flow of current so current through winding is controlled to control the speed

speed of the motor is inversely proportional to the flux means by increasing flux speed decreases

Current is controlled via introducing potentio meter in circuitry



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II. Armature control method[2]

By using this method we can control the speed of motor by controlling armature resistance.

As we know that speed is directly proportional to the armature current which can be proved by equation 1.

……….(1)

If we add resistance in series with the armature just like we adding resistance in flux control method ,Ia decreases and, hence, the speed also decreases. Greater the resistance in series with the armature, greater the decrease in speed.



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III. Voltage control method[2]

As compared to flux and armature control method this method is best because these 2 methods cannot provide speed control in desirable range.

Flux control method affects commutator and armature current gives high power loss.

In voltage control method we control the voltage for controlling speed of motor.

a. Multiple voltage control. In this method shunt field is connected to a fixed voltage and armature is

supplied with different voltages. Voltage across armature is changed with the help of a suitable switchgear.

The speed is approximately proportional to the voltage across the armature.



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b. Ward-Leonard method.

We use this system where sensitive speed control of motors are required.

M2 is the motor whose speed control is required M1 may be any AC motor or dc motor with constant speed. G is a generator directly coupled to M1. In this method the output of the generator is the input of

motor whose speed is to be controlled. The output voltage of the generator G can be varied from

zero to its maximum value by means of its field regulator The armature voltage of the motor M2 is varied



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IV. Pulse width modulation PWM[3]

The technique that is used to control the power deliver across electrical devices.

In PWM power can be controlled across load by changing duty cycle of the signal.

Duty cycle is define as the proportion of on and off time during one cycle.

Off time (Toff) and ON time (Ton) are shown in figure 5.

Formulae for calculating duty cycle is



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4. Results and discussion.



Schematic of PWM, Simulation and their Results.

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b. Servo Motor[5]

Introduction. Servo motor is combination of 4 parts DC motor Feedback system (usually a potentiometer to sense the position of

motor shaft) Gear configuration ( controls movement of the shaft of DC motor) Control circuit (usually a Comparator) • Servo motor used to attain the maximum precision and accuracy of

angular motion or to perform repetitive operations



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Working[5] The entire process operates on Pulse Width Modulation

(PWM), technique used to control devices via variation of duty cycle

Feedback (actual output) from potentiometer is compared with desired output via comparator which yields pulses with different duty cycle, percentage ratio of on time by total pulse time, applied to DC motor.

Gear system controls the movement of Shaft maintains its position on desired output

Block diagram of servo motor is given in following figure7.



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Controlling Speed of Servo motor by using PWM[6] Angular position of servo motor can be controlled

by using pulse width modulation. Interconnections in servo motor driver are shown in

block diagram. For controlling angular position of motor 1st we have

to generate PWM signal, which can be generated by the PWM module of microcontroller or with timers.

Now, we also need to tell the microcontroller how much it has to rotate. For this purpose, we can use a simple potentiometer



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Conclusion.We have various method for controlling speed of motor like flux control method, armature control, voltage control and pulse width modulation .amongst all these method, the best is PWM because it consumes less power ,easy to implement, easy to program and we get accurate results.



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References

1. [1]DC Motor or Direct Current Motor | Electrical4u", Electrical4u.com, 2016. [Online]. Available: http://www.electrical4u.com/dc-motor-or-direct-current-motor/. [Accessed: 29- Nov- 2016].

2. [2]T. Agarwal, "Speed Control Methods of DC Motor - Electrical Projects", Buy Electronics & Electrical Projects in India, 2016. [Online]. Available: https://www.edgefx.in/speed-control-methods-of-dc-motor/. [Accessed: 29- Nov- 2016].

3. [3]"What are the Best Ways to Control the Speed of DC Motor?", ElProCus - Electronic Projects for Engineering Students, 2016. [Online]. Available: https://www.elprocus.com/what-are-the-best-ways-to-control-the-speed-of-dc-motor/. [Accessed: 29- Nov- 2016].

4. [4]"Construction of DC Motor | Yoke Poles Armature Field Winding Commutator Brushes of DC Motor | Electrical4u", Electrical4u.com, 2016. [Online]. Available: http://www.electrical4u.com/construction-of-dc-motor-yoke-poles-armature-field-winding-commutator-brushes-of-dc-motor/. [Accessed: 29- Nov- 2016].

5. [5]"Servomechanism | Theory and Working Principle of Servo Motor | Electrical4u", Electrical4u.com, 2016. [Online]. Available: http://www.electrical4u.com/servo-motor-servo-mechanism-theory-and-working-principle/. [Accessed: 29- Nov- 2016].

6. [6]"Servo Motor Controller or Servo Motor Driver | Electrical4u", Electrical4u.com, 2016. [Online]. Available: http://www.electrical4u.com/servo-motor-controller-or-servo-motor-driver/. [Accessed: 29- Nov- 2016].



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