square wave to sine wave conversion

[bukharee]

guys i'm trying to design a wide range input converter, i'm getting square wave from dc-voltage by using multiviberator, now i want to sonvert this square wave into sine/modified sine wave of same parameters as of my square wave (100-200 v), what should i do?

 

[barry]

How much power do you need?

 

[bukharee]

dear initially power is not the issue, anyways for 500W what should i do?

 

[barry]

I think power IS the issue. I'm not a power guy, but my gut reaction is to create a low-power sinewave and then amplify it. Depending on how pure a sinewave you need , there are several methods (diodes and resistors is one approach). I think it might be very inefficient to convert a high-power squarewave to a sine.

 

[chuckey]

The way to go is via PWM with an output filter to recover the sine wave. This system is used for driving motors up to 50KW. The square wave frequency is normally greater then 5KHz. This is a compromise between switching device losses and size/complexity/ purity of sinewave and the cost of output filter.
Frank

 

[bukharee]

i'm not power guy, this is 1st assignment i got of power, i've heared about sine wave approximations, like 1st order, 2nd order, can it be helpful for me? can i convert square wave into 2nd or third order sine wave? kindly can some one provide me circuit of it?

 

[betwixt]

I think you may be looking at ways to recover a sine wave in small signal circuits, these will not work in high power applications.
If I'm right, what you are looking at is the method of applying filters so that only the fundamental frequency is passed and harmonics are rejected. It is commonly used in small signal circuits but the result is often that 90% or more of the original signal is lost. That isn't an option at 500W levels.

Regenerating a new sine wave using PWM techniques and phase locking to the square wave is a far more efficient route to follow.

Brian.

 

[bukharee]

thts it guys, but tell me how should i proceed, mean can u suggest some circuit regarding tht?

 

[goldsmith]

Dear Friend!
Hi
Your answer is very simple!
if your frequency is more than 5KHZ you can obtain your aim without PWM. but if is low frequency you will need to use differential Class D amplifier to obtain a good sinusoidal output. if your frequency is high , you can amplify your square wave with a simple class D stage (like an H bridge or half bridge) and then you can get your wave to a simple LC filter to have a good high power sinusoidal wave. but what is your frequency that you need? you have many way that depends on your frequency. the power doesn't matter !
Best wishes
Goldsmith