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Everything posted by grateful

  1. I c....but the reason that i use RC filter is because i used the connected load as R. Rload = R filter. Assume that i am using LC filter, what will be the low pass cut off frequency that i should set? is it 50Hz? If so, i set the C = 1000pF then, the L value will be very large,right?
  2. Thanks audioguru :) Now i have increase the PWM frequency to 19kHz. But my inverter design at the output there is a bit different. I use ADC to convert a single phase sinewave with peak amplitude of 5V to PWM signals. Then, the PWM is used to switch or chop the 220Vdc. The output that i obtain now is a PWM with amplitude of 220Vdc for positive half cycle and the negative half cycle (in accordance with the ADC signal). Then, my question is how to design the low pass filter circuit (using RC circuit which is easier to control than LC) which able to smoothen this high voltage PWM signals switching at 19kHz? So, how can i design a RC low pass fiter that able to withstand high power(100W) and high frequency. Then, finally output a perfect 220Vac at 50Hz? ???
  3. Hi there everyone :) I have constructed the H-bridge circuits which is control by PWM, the frequency of PWM is about 4900Hz. Therefore, a single phase PWM sinewave at 220Vrms is generated. Then, my questions are how can i filter this 220Vrms PWM sinewave into a perfect sinewave? Should I choose LC or RC low pass filter? which type of high frequency with high voltage that should i choose for inductor and capacitor component in order to set the cutoff frequency at 50Hz? ???
  4. Hi there, does anyone know how to convert the different width pulses(vertical) of a PWM signal to different height pulses(horizontal) accordingly....any comparator I C can do this ??? Thanks. ;D
  5. I c :o...thanks....but is there any low cost but effective ways to convert a 12VDC to 220VDC? Hi,kachew....at the moment i still on thinking...so,i still not certain with this design yet... :-*
  6. ;DHi,audioguru: what i found is the ferroresonant transformer provides squarewave output but just require less filtering...... if i use PWM method to convert a low VDC to high VDC through a ferro transformer. Then using H-bridge (which is switch by PWM) to chop the high VDC to obtain 240VAC that have multisteps PWM which look like sinewave waveform.... will this work? ???
  7. Hi,audioguru :) i'm interested in constructing a pure sinewave inverter. Do u know any books that talk about how to design this kind of inverter? the ferro-resonant transformer that u mean is it same as the ferromagnetic transformer ???
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