Low power automatic voltage regulator for sensitive equipments by using audio amplification technique

Abstract

In the market there are many choices for Automatic voltages regulators such as auto transformers with relays, servo-mechanism types, Thyristor used types and power inverters type with varying degrees of quality, efficiency, and power output capability. But they cannot be used for low power sensitive applications such as biomedical instruments etc. due to high harmonic content, wave distortions and RFI/EMI issues etc. The High-Frequency Inverter is mainly used today in uninterruptible power supply systems, AC motor drives, induction heating and renewable energy source systems. The simplest form of an inverter is the bridge-type, where a power bridge is controlled according to the sinusoidal pulse-width modulation (SPWM) principle and the resulting SPWM wave is filtered to produce the alternating output voltage. This can be achieved by using a High-Frequency Inverter that involves an isolated DC-DC stage (Voltage Fed Push-Pull/Full Bridge) and the DC-AC section, which provides the AC output. My objective to overcome the said problem is to design a simple Low power Automatic Voltage Regulator for sensitive equipment by using audio amplification technique giving an output waveform as similar to the main supply without moving parts (electro-mechanical devices). It would be a linear mode operating electronic amplifier circuit using bipolar junction transistor (BJT) for 50Hz operation of the main supply. The noise free low signal obtained from the main supply is used as an input signal, having supply frequency (without oscillator) and low voltage. To obtain a controlled noise free standard supply voltage and frequency at the output terminals by the process of power amplification, which could be used for the sensitive equipment in nature such as medical equipment etc.