SPEED CONTROL OF DC MOTOR USING PWM AND PAM
Shubhi Upadhyay,
Departmental Of Electrical Engineering
Shri Ram Murti Smarak Womens College Of Engineering And Technology, Bareilly Affiliated to GBTU,India.
ABSTRACT
The electric drive systems used in many industrial applications require higher performance, reliability, variable speed due to its ease of controllability. The speed command of DC motor is very crucial in applications where precision and protection are of essence. Purpose of a motor speed controller is to take a signal representing the required speed and to drive a motor at that speed. Microcontrollers can provide simple control to DC motor. Microcontroller based speed control system consist of electronic component, microcontroller and the seven segment display LED. In this Paper, implementation of the AT89s52 microcontroller for speed control of DC motor fed by a pwm has been investigated. Controlling the PWM duty cycle is equivalent to controlling the motor terminal voltage, which in turn adjust directly the motor speed. This work is a real one and high feasibility according to economic point of view and accuracy. We provide the gsm calling feature in this project. in this idea of microcontroller enable the darling-ton pair of transistor, the desired objective is to achieve a system with the constant speed at any load condition. That means motor will run at constant speed instead of varying with amount of load.
Keywords- DC motor, Speed control, Microcontroller AT89s52, PWM, PAM
I. INTRODUCTION
Speed control of dc motor could be achieved using mechanical or electrical techniques. In the earlier, speed controls of dc drives are mostly mechanical and requiring large size hardware to implement. Some important applications are: rolling mills, paper mills, machine tools, traction, printing presses, textile mills, cranes. In this project we give a special idea of industrial automation, protection and controlling system.
Today‟s industries are increasingly
demanding process automation in all sectors. Automation provides better quality, increased production economical costs. The variable speed drives, which can control the speed of
A.C/D.C motors, are indispensable
controlling elements in automation systems. It depends upon the applications; some of them are fixed speed and some of the variable speed drives. DC motor drives are used for many speed and position control systems where their super performance, ease of control and high efficiency are desirable
characteristics. Pulse-width modulation
wide speed range, both below and above the rated speed can easily get. The methods of speed control are simpler and less expensive than those of alternating current motors.
II. EXPERIMENTAL SETUP
We make the power supply take it to the step down transformer this transformer convert 220 voltage into 12V and after that rectifier convert into dc voltage ,regulator provide the fixed five voltage .and to give the all component. With the help of switch we control the speed of motor and we give the
four speed by microcontroller output
according to condition enable the transistor and signal compare by lm-358 and amplify by push pull amplifier and signal give to motor. We detect the over temperature on the basis of variation of resistance and out-put give to lm-358 comparator IC and output of control the microcontroller. We detect the over voltage on the basis of variation of resistance and output give to lm-358 comparator IC and output of IC control the microcontroller. We provide the GSM calling feature in this project. In this idea microcontroller enable the darling-ton pair of transistor but we connect the hands-free of phone and GSM phone to hands-free by relay. And these relays operate by the darling –ton pair of transistor.
III.EQUIPMENT USED
1. TRANSFORMER:
This is based on the principle ofTwo coils are wound over a Core such that they are magnetically coupled. The two coils are known as the primary and secondary windings. In a Transformer, an iron core is mostly
used. The coupling between the coils is source of making a path for the magnetic flux to link both the coils.
2.TRANSISTOR: The name is transistor derived from „transfer
resistors‟ indicating a solid state
Semiconductor device. In addition to
conductor and insulators, there is a low class of material that proportion of both. Under some condition, it acts as an insulator, and under other condition, it‟s a conductor. They are of two types mainly which are npn and pnp transistors.
3.CAPACITORS: It is an electronic component whose function is to accumulate charges and then release it. To understand the concept of capacitance, let a pair of metal plates which all are placed near to each other without touching. If battery is connected to these plates the positive pole to one and the negative pole to the other,electrons from the battery will be fascinate from the plate connected to the positive terminal of the battery. If the battery is then not connected, one plate will be left with an excess of electrons, the other with a
shortage, and a potential orvoltage difference
will exists between them. These plates will be used as capacitors.
4. DIODE:
The simplest semiconductor device is made
up of a sandwich of P-type semiconducting
material, with contacts provided to connect
thep-and n-typelayers to an external circuit.
of the battery is connected to the p-type material (cathode) and the negative terminal to the N-type material (Anode), a large current will flow. This is called forward current or forward biased. If the connections are reversed, a very low current will flow. This is due to under this condition, the p-type material will absorb the electrons from the negative terminal of the battery and the N-type material will give up its free electrons to the battery, it results in the state of electrical equilibrium since the N-type material has no more number of electrons. Thus there will be a low current to flow and the diode is called Reverse biased.
5. MICROCONTROLLER (AT89S52):-
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is made by using Atmel‟s high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction set and pin out. The on-chip Flash allow the program memory to be reprogrammed in-system or by
a conventional nonvolatile memory
programmer. By combining a variable 8-bit CPU with in-system programmable Flash on a chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many
embedded control applications. The
AT89S52 provides the following standard features: 8K bytes of Flash,256 bytes of RAM,32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed using static logic for operation down to zero frequency and supports two software selectable power saving modes. The inactive Mode stops the CPU while permit
the RAM, timer/counters, serial port, and interrupt system to continue functioning.
ARCHITECTURE 0F AT89S52:
PIN DIAGRAM:
system used for choosing menu options in communication with an automated call
handling service. Tones can only be sent
over an active and connected voice calls. The caller does not need a handle to the specific call. The telephony system can send the tones over the voice calls that are connected. DTMF (Dual Tone Multiple Frequency)application is associated with digital
telephony, and provides two selected output frequencies (one high band, one low band) for a duration of 100 ms. In Interfacing DTMF 8870 is very simple but is should be done with proper care about the circuit designing.
Here we will discuss simple project of caller id with 8051 Microcontroller. This Project can be used in industrial purpose for controlling the speed of DC Motor. This keeps an eye on every incoming number on the selected telephone line. Basically it is the built in caller id system. When telephone rings it displays the telephone number on the screen attached with the circuit. 8052 Microcontroller is responsible for every operation in the given project from controlling DTMF IC and LED.
IV. PULSE WIDTH MODULATION
Pulse width modulation control works by switching the power supplied to the motor on and off very rapidly. PWM for motor speed control works in a very similar way. Instead of supplying a varying voltage to a motor, it is supplied with a fixed voltage value (such as 12v) which starts it spinning immediately. The wave forms in the below figure to explain the way in which this method of control operates. In each case the signal has maximum and minimum voltages of 12v and 0v.
In wave form, the signal has a mark
space ratio of 1:1.with the signal at 12v for 50% of the time, the average
voltage is 6v, so the motor runs at half its maximum speed.
In wave form, the signal has mark
space ratio of 3:1.which means that the output is at 12v for 75% of the time. This clearly gives an average output voltage of 9v, so the motor runs at 3/ 4 of its maximum speed.
In wave form, the signal has mark
space ratio is 1:3, giving an output signal that is 12v for just 25% o the time. The average output voltage of this signal is just 3v, so the motor runs at 1/4 of its maximum speed. By varying the mark space ratio of the signal over the full range, it is possible to obtain any desired average output voltage from 0v to12v.
V. PULSE AMPLITUDE MODULATION
Pulse-amplitude modulation (PAM), is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. It is an analog pulse modulation scheme in which the amplitudes of a train of carrier pulses are varied according to the sample value of the message signal. Pulse amplitude modulation (PAM) is the transmission of data by varying the amplitudes (voltage or power levels) of the individual pulses in a regularly timed sequence of electrical pulses. The number of possible pulse amplitudes can be infinite (in the case of analog PAM), but it is usually some power of two so that the resulting output signal can be digital .
VI.ADVANTAGES
1. PWM Technique enables greater
VII.CONCLUSION
The dc motor speed is controlled by using power electronic converter circuit. The PWM and PAM technique is used to control the speed of dc motor the speed sensor is used to detect the speed and closed loop control systems is used for pulse circuit. The speed pulse train will be based on required input speed. This circuit is useful to operate the dc motors at required speed. The circuit response time is too low. Hence high reliability can be achieved. The designed circuit was tested for various speed inputs satisfactorily by using micro controller AT89S52.
VIII.REFRENCES
1. Gopal.K.Dubey “Fundamentals of Electric Drives”
Narosa Publishing House New Delhi, 1989.
2. Muhammad H. Rashid, „„Power
Electronics Circuits, Devices, and
Applications,” Prentice Hall, 3rd
edition, 2003.
3. A Khoei Kh. Hadidi, “MicroProcessor Based Closed- Loop Speed Control System for DC Motor Using Power MOSFET”, 3rd IEEE international conference on Electronics, Circuits and Systems(1996) vol.2.
4. Pulse width modulator module (PWMM), AT89S52 data sheet.
