power factor

Microcontroller-Based Single-Phase Automatic Voltage Regulator
Nang Kaythi Hlaing

Lwin Lwin Oo

Hardware Technology Department
Computer University(PangLong)
Myanmar
[e-mail]

Hardware Technology Department
Computer University(Larshio)
Myanmar
[e-mail]
This design is based on the principle of phase control of ac voltage using a triac, where triggering (firing) delay is determined by the PIC microcontroller. Fig. 1 shows the important components of our AVR.

Abstract— This paper proposes the design and implementation of a microcontroller-based single-phase automatic voltage regulator (AVR). The basic building blocks for this design include a PIC 16f 628 microcontroller, a triac, a step-up transformer, a zero crossing circuitry and a load voltage sensing circuitry. This design is based on the principle of phase control of ac voltage using a triac. The trigger pulse for the triac is delayed by the microcontroller to provide the desired regulator terminal voltage. This voltage is always sensed and fed back to the microcontroller via a measuring unit to get a continuous control system. One of the intensions to develop this
AVR is to use it in domestic heating and lighting controls. It can also be used as an adjustable voltage source by adjusting a variable resistor in the voltage sensing circuitry. It is also intended to introduce a compact AVR and to demonstrate the usefulness of the PIC microcontroller in power control field.
Keywords-Automatic voltage regulator (AVR); microcontroller; autotransformer; phase control; triac

I.

PIC

INTRODUCTION

The automatic voltage regulator or AVR, as the name implies, is a device intended to regulate voltage automatically: that is to take a varying voltage level and turn it into a constant voltage level [4]. Automatic voltage regulators are widely used in electrical power field to obtain the stability and good regulation of the electric system. In

References: A. Ahmed, Power Electronics for Technology, Prentice-Hall International, 1999. J. B. Peatmann, Design with PIC Microcontrollers, Prentice-Hall, 1998. J. M. Jacob, Power Electronics: Principles and Applications, Vikas Publishing House, 2002. M. C. Sharma, Voltage Stabilizers and Automatic Cutouts, 1987. P. C. Sen, Power Electronics, Tata McGraw-Hill Publishing Company Limited, New Delhi, 1987. R. A. Penfold, An Introduction to PIC Microcontrollers, Bernard Babani Publishing, 1997.