NAME:ASHUTOSH SRIVASTAVAROLL NO.-0806421013

MICROPOWER ELECTROSTATIC GENERATOR

(MEG)

OUTLINE:

What is “Micropower Electrostatic Generator (MEG)”

Basic principle of Operation Circuit Diagram Comparison with conventional electro static

generator Application Research topics References

MICROPOWER ELECTROSTATIC GENERATOR (MEG):

It is a micro machined, vibration-driven generators employing electrostatic phenomena to convert the kinetic energy of a mass into electrical energy at microwatt level.

They have required mechanical vibrations to excite a resonant structure.

Micropower electrostatic generators are capable of powering electronic circuits.

BASIC PRINCIPLE:

The generator considered here is of a capacitive type .

The capacitor is formed by one electrode which is weighted and free to move

Second electrode which is stationary relative to the chip.

System overview of MEG:

CIRCUIT DIAGRAM:

Simple circuit representation for a MEG

To initiate a generation cycle, the capacitor is pre-charged to a low voltage V1.

Accelerating the device causes the weighted electrode to move against the attractive force between the electrodes, thereby increasing the potential energy in the system.

If the charge q is held constant, the capacitor voltage increases, and the increase in potential energy is given by

where V2 is the finishing voltage. Substituting the standard relationships for

parallel plate

The basis of electrostatic energy conversion is the variable capacitor. The variable capacitance structure, is driven by mechanical vibrations and oscillates between a maximum capacitance (Cmax) and a minimum capacitance (Cmin).

If the charge on the capacitors constrained, the voltage will increase as the capacitance decreases.

If the voltage across the capacitor is constrained, charge will move from the capacitor to a storage device or to the load as the capacitance decreases.

In either case, mechanical kinetic energy is converted to electrical energy. When Cv is at Cmax, switch 1 (SW1) closes, and charge is transferred from the input to the variable capacitor.

Putting the values according to diagram . Energy obtained by MEG is given by the :

Comparison with conventional Electrostatic generator

Micro power electrostatic generator

Conventional electrostatic generator

PRODUCES LOW POWER ( µW)

PRODUCES HIGH POWER (W,kW)

VERY SMALL IN SIZE SIZE IS BULKY

APPLICATIONS:

As small source of voltage Low power VLSI design CMOS fabrication In pacemakers in medical field In power electronics

Research Topics:

Self powered signal processing. Use of piezoelectric force instead of vibration. Development of an electrostatic generator that

uses the motion of a living body.

REFERENCE:

Internetwww.wikipedia.comwww.google.com C. B. Williams and R. B. Yates “Analysis of a

micro-electric generator for microsystems” S. Meninger, J.O. Mur-Miranda,

R.Amirtharajah, A.P. Chandrakasan, J.H. Lang, Vibration-to-electric energy conversion, IEEE Trans.