Speed Control of Dc Motor Using Lm317 Voltage Regulator

 Speed control of DC Motor Project Abstract Introduction. Background. Abstract Method of procedure. Circuit diagram. List of components. Pre-assembling on breadboard. PCB making and soldering components. Working. Results. Conclusion. References 1

Project Abstract Our project is the speed control of DC Motor circuit that is built and constructed around an LM317 - Three-Terminal Adjustable Positive Voltage Regulator. This circuit can deliver up to 1.5A of continuous current with proper heat sinking. Although the LM317 can deliver voltages of up to 37V, the circuit I designed is built to produce output voltages of 1.2V to < 24V. With internal characteristics like, Internal Thermal Overload Protection and Internal Short Circuit Protection offered by the LM317, there is no need for other external components to be added into this circuit, hence, reducing the parts count and cost. This circuit is essential for other circuits requiring both (+) and (-) voltage power supply like most operational amplifier circuits.

INTRODUCTION It is a simple speed control of DC Motor whose speed can be controlled by varying volts 1.2 to 24v dc volts. Here we u s e a s i m p l e f u l l w a v e r e c t i f i e r a l o n g w i t h a v o l t a g e r e g u l a t o r w h i c h g i v e s a constant output and its output can be increased by using a pair of voltage divider resistor in which one resistance is variable to get variable output

➢ CIRCUIT DIAGRAM The circuit diagram of dc power supply using bridge is as follows:

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The main components used in this circuit are:• • • • • • • •

DC Motor Transformer Fuse Switch Diodes Capacitors Variable resistor Fixed resistor

•

IC LM317

LM317 Pin outs

Semiconductors:○ IC1 = LM317 (1) ○ D1-D4 = 1N40001 or ○

W04M bridge diode (4)

LED 1 - Multicolor(1) 3

Resistors:○ R1 = 240Ω 1/4W 5% tol.(1) ○

VR1 = 5.0kΩ Potentiometer (1)

Capacitor:○ C1 = 3300µF/50V elect. (1) ○

C2 = 0.1µF Mylar (1)

○ C3 = 10µF/50V elect. (1)

Miscellaneous:○ T1 = 110/220V Input 0V - 24V 300mA Output Transformer (1) ○ S1 = ON/OFF Toggle Switch (1)

AllParts:○ IC1 = LM317 (1) ○ R1 = 240Ω 1/4W 5% tol.(1) ○

VR1 = 5.0kΩ Potentiometer (1)

○ C1 = 3300µF/50V elect. (1) ○

C2 = 0.1µF Mylar (1)

○ C3 = 10µF/50V elect. (1) ○ D1-D4 = 1N40001 or W04M bridge diode (1) ○ T1 = 110/220V Input 0V - 24V 2.0A Output Transformer (1) ○ S1 = ON/OFF Toggle Switch (1) ○

* Use an adequate heat sink for IC1.

The description of the parts of circuit designed is given below:-

DC Motor:

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When a rectangular coil carrying current is placed in a magnetic field, a torque acts on the coil which rotates it continuously. When the coil rotates, the shaft attached to it also rotates and thus it is able to do mechanical work.

Working of DC Motor: When the coil is powered, a magnetic field is generated around the armature. The left side of the armature is pushed away from the left magnet and drawn towards the right, causing rotation.

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When the coil turns through 900, the brushes lose contact with the commutator and the current stops flowing through the coil. However the coil keeps turning because of its own momentum. Now when the coil turns through 1800, the sides get interchanged. As a result the commutator ring C1 is now in contact with brush B2 and commutator ring C2 is in contact with brush B1. Therefore, the current continues to flow in the same direction.

Types of DC Motor: There are three main types of DC Motor:

Series motor Shunt motor Compound Motor

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Transformer:Two coils of wire linked by an iron core. Transformers are used to step up (increase) and step down (decrease) AC voltages. Energy is transferred between the coils by the magnetic field in the core. There is no electrical connection between the coils. The external figure of transformer is shown below

This is a center type transformer. The above shown transformers are step down which converts 220-240V to 24V. Some of the description about the used transformer is given below:• • • • • •

Type Model Brand Rating Input V Output V

•

Symbol

Control 90-T40F3 WHITE-RODGERS 40VA 220-240V, 50Hz 24V

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Diode Bridge:A diode bridge is an arrangement of four (or more) diodes in a bridge circuit configuration that provides the same polarity of output for either polarity of input. When used in its most common application, for conversion of an alternating current (AC) input into direct current a (DC) output, it is known as a bridge rectifier. A bridge rectifier provides full-wave rectification from a two-wire AC input, resulting in lower cost and weight as compared to a rectifier with a 3-wire input from a transformer with a center-tapped secondary winding.

The Full Wave Bridge Rectifier Another type of circuit that produces the same output waveform as the full wave rectifier circuit above, is that of the Full Wave Bridge Rectifier. This type of single phase rectifier uses four individual rectifying diodes connected in a closed loop "bridge" configuration to produce the desired output. The main advantage of this bridge circuit is that it does not require a special centre tapped transformer, thereby reducing its size and cost. The single secondary winding is connected to one side of the diode bridge network and the load to the other side as shown below.

The Diode Bridge Rectifier

The four diodes labelledD1 to D4 are arranged in "series pairs" with only two diodes conducting current during each half cycle. During the positive half cycle of the supply,

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diodes D1 and D2 conduct in series while diodes D3 and D4 are reverse biased and the current flows through the load as shown below.

The Positive Half-cycle

During the negative half cycle of the supply, diodes D3 and D4 conduct in series, but diodes D1 and D2 switch "OFF" as they are now reverse biased. The current flowing through the load is the same direction as before.

The Negative Half-cycle

As the current flowing through the load is unidirectional, so the voltage developed across the load is also unidirectional the same as for the previous two diode full-wave rectifier, therefore the average DC voltage across the 9

load is 0.637Vmax. However in reality, during each half cycle the current flows through two diodes instead of just one so the amplitude of the output voltage is two voltage drops ( 2 x 0.7 = 1.4V ) less than the input VMAX amplitude. The ripple frequency is now twice the supply frequency (e.g.100Hz for a 50Hz supply).

The Smoothing Capacitor The full-wave bridge rectifier however, gives us a greater mean DC value (0.637 Vmax) with less superimposed ripple while the output waveform is twice that of the frequency of the input supply frequency. We can therefore increase its average DC output level even higher by connecting a suitable smoothing capacitor across the output of the bridge circuit as shown below. Full-wave Rectifier with Smoothing Capacitor

The smoothing capacitor converts the full-wave rippled output of the rectifier into a smooth DC output voltage. Generally for DC power supply circuits the smoothing 10

capacitor is an Aluminium Electrolytic type that has a capacitance value of 100µF or more with repeated DC voltage pulses from the rectifier charging up the capacitor to peak voltage.

LM317:3-Terminal Adjustable Regulator General Description

The LM317 series of adjustable 3-terminal positive voltage regulators is capable of supplying in excess of 1.5A over a1.2Vto 35V output range. They are exceptionally easy to use and require only two external resistors to set the output voltage. Further, both line and load regulation is better than standard fixed regulators. Also, the LM317 is packaged in standard transistor packages which are easily mounted and handled.

In addition to higher performance than fixed regulators, the LM317 series offers full overload protection available only in IC's. Included on the chip are current limit, thermal overload protection and safe area protection. All overload protection circuitry remains fully functional even if the adjustment terminal is disconnected.

Features

■ Guaranteed 1% output voltage tolerance (LM317A) ■ Guaranteed max. 0.01%/V line regulation (LM317A) ■ Guaranteed max. 0.3% load regulation (LM117) 11

■ Guaranteed 1.5A output current ■ Adjustable output down to 1.2V ■ Current limit constant with temperature ■ P+ Product Enhancement tested ■ 80 dB ripple rejection ■ Output is short-circuit protected

Resistor (Fixed & Variable):• Fixed resistance

The power or capacity to resist is known as resistance. Or The opposition offered by a body or substance to the passage through it of a steady electric current.

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The resistance of the resistor can be found by using color coding or by using DMM. In the circuit of power supply, we often use the resistor of 270Ω, which is shown below:

A resistor restricts the flow of current, for example to limit the current passing through an LED. A resistor is used with a capacitor in a timing circuit. Some publications still use the old resistor symbol: • Variable Resistor:This type of variable resistor with 2 contacts (a rheostat) is usually used to control current. Examples include: adjusting lamp brightness, adjusting motor speed, and adjusting the rate of flow of charge into a capacitor in a timing circuit. 13

Capacitors:A capacitor stores electric charge. This type must be connected the correct way round. A capacitor is used with a resistor in a timing circuit. It can also be used as a filter, to block DC signals but pass AC signals.

There are many types of capacitor. Most common are ➢ Polar capacitor ➢ Non-Polar capacitor

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Switch:In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another.

In electronics engineering, an ideal switch describes a switch that: • has no current limit during its ON state • has infinite resistance during its OFF state • has no voltage drop across the switch during its ON state • has no voltage limit during its OFF state •

has zero rise time and fall time during state changes

• switches only once without "bouncing" between on and off positions Practical switches have loss and limitation. The ideal switch is often used in circuit analysis as it greatly simplifies the system of equations to be solved, however this can lead to a less accurate solution. 

METHOD OF PROCEDURE 15

This section includes all the steps and the action we do for the making of our project and it also cover the method we adopt during the complication of our project. We make a variable dc power supply and the main working principle of this project is full wave rectification which is done by bridge configuration in which we are using 4 diodes which rectifies the output of the step-down transformer which step-down the 220 AC v to 24 AC volts .Here we are using a voltage regulator which give constant voltage, here we are using LM317T which give 1.2 up to 24 volts. Now the main task is to get variable output to vary the speed of DC Motor for this we use the pair of voltage divider resistors to increase the output of the regulator and in which resistance is variable so when we increase or d e c r e a s e t h e v a l u e o f t h a t r e s i s t o r t h e o u t p u t v o l t a g e o f t h e r e g u l a t o r w i l l a l s o change and we get a range of 1.2 to 24 v, here we can’t get less than 5 volts because this is the output of the regulator. In this circuit we use three capacitor , c1 is 1000 µF and c2 is 0.1 µF are use to get constant input to the regulator more over it also help to reduce the sharp peaks in the output . connect the 0.1 µF capacitor to close to the input of the regulator and the 1µf capacitor to the output because these capacitor reduce the noise and also help to reduce the ripples produce by the regulator so that regulated output has less ripples.

 PRE-ASSEMBLING ON BREADBOARD Before making the circuit on the PCB or on wiro-board makes it on the breadboard and we also make it in LAB and our lab assistants had also checked it.

 PCB MAKING & SOLDERING COMPONENTS If your circuit works on the breadboard .Then the next step is to make the circuit on the pcb or on wiro-board. Here I make the keypad on the pcb while the other circuit is made on the wiro-board. For pcb making recall all the steps involved in pcb designing a n d m a k e , f i r s t m o u n t t h e c i r c u i t i m a g e o n t h e p c b a n d d o t h e e t c h i n g a f t e r t h i s solder the components on pcb and also the components on the wiro-board. 16

 WORKING The main working principle of this project is full wave rectification which is done by bridge configuration in which we are using 4 diodes which rectifies the output of the step-down transformer which step- down the 220 AC volts to 24 AC volts. Here we are using a voltage regulator which gives constant voltage, here we are using LM317T which give 1.2 up to 35 volts. These regulators are available in various outputs like 6v, 9v, 12v and 15v. Fig 1: pin configuration of LM317TNow the main task is to get variable output for this we use the pair of voltage divider resistors to increase the output of the regulator and in which of resistance is variable so when we increase or decrease the value of that resistor the output voltage of the regulator will also change and we get a range of 1.2 to 35 v , here we can’t get less than 5 volts because of this is the output of the regulator here the given below fig shows the increasing output voltage.

 RESULTS AND OBERVATIONS So at the end our variable dc power supply is completed which give variable dc volts and it ranges from 5 to 12 v here we can’t get less then 5 v because it is the output voltage of the regulator which can be increased.

 REFRENCESS I collected the data from the mention below sites our teachers and our text book also helps a lot. ➢

http://www.radio-electronic.com/

➢

http://www.pcbheaven.com/

➢

http://www.circuittoday.com/

➢

http://www.Wikipedia.com 17

➢

http://www.allaboutcircuit.com

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