A simple, economic, pure sine wave dc/ac inverter applicable up to 500VA output power. Easily repairable. Designed by Subarna Giri (electrical systems control technologist) Be free from IC-type model Be eco-friendly

1. WELCOME TO THE OVERVIEW OF
INVERTER DESIGN PROJECT

2. SCHEMATIC CIRCUIT DESIGN IN AUTOCAD

3. BASIC PRINCIPLE OF INVERTER
State S1 S2 Output Voltage
1 + − +E
2 − − 0
3 − + −E
4 + + 0

4. ASTABLE
MULTIVIBRATOR
Duty Cycle (D) = Thigh/(Thigh + Tlow)= 50%
Output Frequency = 1/(Tlow + Thigh) =
1.44/((Ra + 2Rb) * C) = 60 Hz
RA = 3.3𝐾Ω , RB = 107.5𝐾Ω
& C = 0.11µF

6. SWITCHING CIRCUIT
When high signal comes from
oscillator it activates transistors
bringing it in forward biased.
As soon as the transistor saturated
the current flows from Collector to
emitter and works as switch on.
When input signal to the base is zero
the transistors are reversed biased
and there is no flow of current from
Collector to Emitter and hence the
switch is off.

7. STEP-UP
TRANSFORMER
Primary supply 12 –
0 – 12 Volts 2.5A
Square wave
Secondary output
123 Volts, 245mA
Square wave
Power rating 30VA

8. SQUARE TO
SINEWAVE
CONVERTER
The figure shows the
conversion of square
wave in to the sine
wave.
The circuit has been
design after careful
theoretical calculation
This simulation has
been done in
Electronic WorkBench
http://tinyurl.com/hjbn6bx
190V

10. CIRCUIT ANALYSIS
The circuit analysis has been
done using Thevenin
theorem.
The voltage drop in the
circuit is around 6volts and
power dissipation is 0.2VA.
Vrms output from this circuit
is 130V when supplied 190V
square-wave signal.
Practical circuit gives 119V

11. LCR CIRCUIT
ANALYSIS
Capacitor charging process is
given by
 Inductor Charging process is
given by
Capacitor Discharging
Inductor Discharging

12. A COMPLETE INVERTER CARD

13. http://tinyurl.com/k8y34xb

15. COMMERCIAL APPLICATION
Inverter is widely used every where in industrial,
household and official appliance for power back
devices.
Ac power is convenient for long distance power
transmission.
Power produced from windmill and solar panel
often saves in storage cell. Inverter is the primary
device for the conversion of the DC power into the
AC power.

16. CONT.……….
Continuous running motor and other signal processing
sophisticated devices need pure sine wave.
However, it is expensive pure sine wave generator often
installed as apart of an inverter.
sampling circuits, thyristor firing circuits, frequency generator
circuits, tone generator circuits etc. use triangular Wave
The inverter is widely used to the regions where power supply
interruption is frequent costumes.

17. CHALLENGES AND TROUBLESHOOTING
The power transistors heat quickly due to the
rapid switching. It is minimized by the help of heat
sink and current limiting resistors.
It is very difficult to design square wave using 555
timer however, 51% duty cycle is maintained.
The voltage drops drastically when converts
square wave to sine wave. The problem is figured
out but not implemented
Tolerance of components is the major factor in
the implementation of designed electronic circuit.

18. CONCLUSION
In spite of many problems encountered during
the designing of the project, almost all problems
are solved.
The theoretical and methodology parts are pretty
enough for upgrading high power sine wave
inverter
Lack of low resistance high current inductor and
high power CT transformer this project is limited
to low power supply.

19. THANK YOU
The end