Active Power Filter Using Atmega16

[ujjwol77]

I am doing a project called ACTIVE POWER FILTER and I have to identify the fundamental frequency component of a signal using Atmega16. Now i believe I have two use DFT or FFT to extract the fundamental frequency component from a signal. But I am having a hard time implementing this on ATmega16.
Can anyone help me?

 

[FvM]

A detailed project specification could clarify a lot. I would expect a rather limited frequency range (assuming it's about mains power) at worst 50 - 60 Hz plus some margin. That's not a reasonable FFT application. I would either think about a digital band pass filter, a FFT-like Goertzel filter, or a PLL.

 

[ujjwol77]

thank u for the reply!! yes i am only concerned with the mains signal ... i have read about the goertzel algorithm. can u give me some ideas on implementing it in
atmega16 microcontroller?

is there any other ways i can extract the fundamental component without using microcontrollers?

 

[FvM]

The Goertzel algorithm effectively calculates a single line of the FFT by multplying the input signal with a discrete complex sinewave of the respective frequency and summing the product over the indended sequence length. So it requires to know the fundamental frequency. If your intended output is a continuous fundamental wave, I would prefer a band pass filter. Of course an analog filter can be used as well. If you don't need the signal in the digital domain, I would be the preferred method anyway, and with limited processor resources, possibly also as an analog pre-filter.

 

[ujjwol77]

by band pass filter do u mean builiding a fitler with opamps??
would such a filter be accurate enough to extract 50hz signal while rejecting all the harmonics?

and i couldnt understand what u mean by an analog pre-filter

 

[FvM]

Yes, a analog fundamental filter will be easy. Pre-filter meaned the case, that you would want to process the voltage by a microprocessor, but prefer an analog filter.

 

[hiangcuong]

Hi,
I'm also doing a project about Active Power Filter. I have employ the hardware with time domain algorithm but faced some problem.
By now I decide change to use FFT algorithm. Can you tell me what is the drawback and difficult of FFT?
Can you give me you email address, I think we have a lot to discuss.
Thanks and regards,
Cuong.

 

[ujjwol77]

well the main difficulty i am facing is performing FFT on microcontrollers with there limited memory and processing powers!!! Meanwhile i am trying to design a microcontroller based STATCOM device using the Hysteresis Band PWM Controller. The topics are quite related. I would be glad to discuss with you