GOVERNMENT COLLEGE OF ENGINEERING, CHANDRAPUR

ELECTRICAL ENGINEERING DEPARTMENT2014-15

ARM CORTEX ( LPC 2148 ) BASED MOTOR SPEED CONTROL

GUIDED BY-PROF.S.P.JOLHE

PRESENTED BY

1. UDAY D. WANKAR 7. VARSHA V. HIWARE2. GOPAL K. MOTI 8. LAKSHMI SINGH3. PRATIK A. SAKHARKAR 9. RUPALI N. GHTUKE4. KUNAL R. PATIL5. SURENDRA M. BUTALE6. VILAS J. DORLE

Introduction

AC motors have been widely used for the industries since

earliest days of electrical engineering.

The project is designed to control the speed of a DC and AC

motor using ARM7 LPC2148 processor .

This project uses the PWM principle to control the speed of the

motor by varying the duty cycle of the pulses applied to it known

as PWM Control.

The project uses the input button interfaced to the processor.

A motor driver IC is interfaced to the ARM7 LPC2148 processor

board for receiving PWM Signal.

HARDWARE REQUIRED

Power Supply

LPC 2148 Development Board

LCD

Control switch board

L293D Driver IC

Optocoupler (MOC 3021)

TRIAC BT136

Snubber Circuit

Working Principle

If voltage across motor terminal is varied, then speed canalso be varied. This project uses the above principle tocontrol the speed of the motor by varying the duty cycle ofthe pulses applied to it, popularly known as PWM control.

The average voltage given or the average current flowingthrough the motor will change depending on the duty cycle,ON and OFF time of the pulses, so the speed of the motorwill change.

Pulse Width Modulation (PWM)what is it? Output signal alternates between on and off within specified

period

Controls power received by a device

The voltage seen by the load is directly proportional to thesource voltage

Definition

Duty Cycle: on-time / period

Vlow is often zero

LOWHIAVG VDDVV )1(

PWM signals of varying duty cycles

Block diagram of our system

Architecture of implemented system

ARM LPC2148

32 bit ARM7 microcontroller in a tiny LQFP64 package.

40kb of on-chip RAM.

512kb of on-chip flash memory.

High speed 60 MHz operation.

Two analog to digital converters(10 bit).

Total 14 ADC inputs in LPC2148.

6 PWM outputs.

Pin diagram of LPC2148

Control Switches

On pressing clockwise or anticlockwise button ,LPC configure output for clockwise or anticlockwise direction.

On pressing low sped or high speed button motor start rotation in clockwise direction.

DC motor driver circuit

L293D is a dual H-bridge motor driver integrated circuit(IC).Motor drivers act as current amplifiers since they take alow-current control signal and provide a higher-currentsignal.

Features:

Wide supply-voltage range:4.5V to 36V

Separate input-logic supply

Internal ESD protection

Thermal shutdown

High-Noise-Immunity input

Output current 1A per channel(600 mA for L293D)

Output clamp diodes for inductive Transient Suppresion (L293D)

Schematic of L293D

AC motor driver

Ac motor driver circuit uses optoisolator MOC3021, TRIACBT136 and snubber circuit. The process is carried out at highfrequency, switching load on and OFF thereby controlling powerto the load.

Optoisolator (MOC3021)

Optoisolator MOC3021 is 6 pin IC & is made up of lightemitting diode and DIAC which are Electrically isolated.

Optoisolator allows two circuit to exchange signal yetremain electrically isolated.

The light is proportional to the signal, so the signal istransferred to the photodiac.

This is the principle used in opto triac and opto SCRswhich are readily available in IC form.

The isolation between low power and high power circuitsin this optically connected device is several thousandvolts.

Optoisolator MOC3021 is mainly used as TRIAC driverin this project

TRIAC

TRIAC is a bidirectional triode thyristor.

It can be triggered by either a positive or negative voltagebeing applied to its gate electrode.

TRIAC is allowing the control of very large power flows withmA-scale control currents for ac circuit.

Applying trigger pulse at a controllable point in a AC cycleallows one to control the percentage of the current that flowsthrough TRIAC to the load.

Snubber circuit

The main function of snubber circuit is to improve theswitching behavior of the TRIAC at turn off.

It is often designed with a network made of a resistor Rand a capacitor C, the SNUBBER circuit.

This circuit can also be used to improve TRIACimmunity to fast transient voltages.

Result of DC motor Control

PWM signals from LPC2148 is given to L293D which controls 12V or greater voltage by 5V dc from PWM pins.

At 30% duty cycle PWM signals, DC motor runs at low speed.

At 90% duty cycle PWM signals, DC motor runs at high speed.

50% PWM signal is given to MOC3021, DIAC inMOC3021 triggers triac gate only 50% of single pulsei.e. TRIAC is on for 50% of time. AC motor runs atlower speed.

Result of AC motor Control

90% PWM signal is given to MOC3021, DIAC in MOC3021 triggers triac gate only 90% of single pulse i.e. TRIAC is on for 90% of time. AC motor runs at higher speed.

Conclusion

1. The main aim of this project is to control the speed of motor

using PWM technique by ARM processor.

2. Implementation is easy and understandable.

3. User friendly project.