50 Hz frequency Low Pass Filter Design

Discussion in 'The Projects Forum' started by Ahmed Nadeem, Feb 12, 2014.

  1. Ahmed Nadeem

    Thread Starter New Member

    Jan 14, 2014
    4
    0
    Hey Everyone

    I have to design a Low pass RC filter of 50Hz output frequency for 150 Watt sine wave inverter. Input peak Voltage of PWM is signal is 12 V. The carrier frequency of PWM is 8 kHz.


    P[​IMG]
    the picture of 50Hz sine PWM

    Please help me about the components and values of passives used in fliter..

    Thanks in advance :)
     
    Last edited: Feb 12, 2014
  2. crutschow

    Expert

    Mar 14, 2008
    13,013
    3,233
    Is this a low power signal or a high power signal that you want to filter? What degree of filtering do you need (how much 8kHz ripple is allowed)?
     
  3. Ahmed Nadeem

    Thread Starter New Member

    Jan 14, 2014
    4
    0
    Hello Crutschow.. It is a high power signal with 12 V peak. The output power depends on load. I need maximum filtering.. i.e Pure 50Hz sine output with minimum ripples of 8kHz. :)
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,013
    3,233
    You don't want to filter a high power signal with an RC filter since it will dissipate power, reduce the efficiency, and give poor voltage regulation with a change in output load. You need an LC filter.

    "Maximum filtering" is not a numerical value. What value is "pure" and "minimum ripples"?
     
    Last edited: Feb 13, 2014
  5. Ahmed Nadeem

    Thread Starter New Member

    Jan 14, 2014
    4
    0
    Then how can I design the LC filter? Actually problem is that in my city Inductors of fixed value are not available :( Please provide me any solution..
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,013
    3,233
    The value of the inductor depends upon how much you need the 8kHz suppressed. You need to assign a number to the amount of attenuation you need (the amount of 8kHz ripple you can tolerate (1mV, 10mV, 100mV, etc.). Without that value you can't do a design. Of course, the lower the allowed ripple, the higher the inductance required, and the larger and more expensive is the inductor. One of the difficult parts in doing a design is often in determining what the acceptable performance parameters are so that the system performs the job adequately without unnecessarily tight (and perhaps expensive) design requirements. This is such a situation.

    If you can't buy inductors (that sees odd), then can you buy ferrite magnetic cores and make you own inductors?
     
Loading...