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AKINOLA
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Converting DC to Sine Wave

03/12/2010 4:57 PM

how can i change a dc to sine wave

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Tornado
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#1

Re: need to know

03/12/2010 5:00 PM

By using an inverter.

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Hameedullah Ekhlas
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#2

Re: need to know

03/12/2010 5:12 PM

Use four diode and make a bridge. see this link

http://upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Diode_bridge_alt_2.svg/557px-Diode_bridge_alt_2.svg.png
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msamad
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#3
In reply to #2

Re: need to know

03/12/2010 5:50 PM

For convenient, I am pasting my comment here with little change and addition:

Most common inverter technologies are:

- Pulse-width modulation (PWM)

- Ferroresonant and

- Step wave

These technologies are the result of different SCR circuits, gate controls, and output filtering techniques.

(1) Pulse-width modulation (PWM): It converts DC to AC by using power switching at a 20 kHz to 50 kHz rate. A linear feedback loop is part of the circuitry. The output is a pulse-width modulated positive and negative square wave. A simple output low-pass filter removes the high frequency carrier for a smoothed sine wave. Most of the VFD and UPS inverter use this technology.

(2) Ferroresonant: It converts DC to AC by generating a square wave filtered by a ferroresonant transformer, creating a true sine wave output. The ferroresonant transformer is a "tuned" nonlinear transformer. UPS uses this technology especially when the constant voltage is required. The ferroresonant transformer operates in the magnetic saturation region and hence a larger input voltage variation causes smaller output variation.

(3) Step wave: Power semiconductors and phase shifting networks create a six- or 12-step "staircase" waveform which is then filtered into a sinusoidal shape. It takes a semiconductor device plus a phase shift for each step in the output voltage waveform. This technology is rarely used now-a-days.

For additional help, see

http://www.dieboldpwr.com/pwmferro.html

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redfred
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#4
In reply to #2

Re: need to know

03/12/2010 10:50 PM

Ah, no a diode bridge will convert a sine wave to a DC voltage. The OP wishes to go the other way and change a DC voltage into a sine wave.

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dvmdsc
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#6
In reply to #2

Re: need to know

03/17/2010 10:06 PM

The question was DC to AC if I remember. Your proposition is a bridge rectifier? That works only the other way: AC to DC. You need at least a chopper to cut the DC into pieces - on-off- many times per second. Then the output shape becomes roughly square pulses that can be transformed to an AC voltage. An inverter can do this for you.

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redfred
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#5

Re: Converting DC to Sine Wave

03/12/2010 11:10 PM

You don't really give enough information here to give you an accurate approach to convering a DC signal to a sine wave. To be specific, one would need to know the desired AC voltage frequency and desired power levels. If you wish an AC power distribution voltage then purchasing an inverter for the power you wish is your best bet.

If instead you wish something else then what you need is an oscillator circuit. There are many topologies that oscillate. There's the Wien bridge, the Colpitts, and the Armstrong oscillator circuits to just name a few.

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#7
In reply to #5

Re: Converting DC to Sine Wave

03/23/2010 11:46 PM

Can the Wien bridge oscillator simulated in Multisim ? I have tried, but the result still DC. Please help ??
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redfred
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#8
In reply to #7

Re: Converting DC to Sine Wave

03/24/2010 11:59 PM

No time right now for a full response but you've stumbled onto a common simulation problem. Spice (the root analysis program of nearly all circuit simulation programs) does an initial quesent DC analysis before stepping into a transient analysis. So to get this 0 frequency start point, all AC components get dialed back to zero magnitude. The trouble comes in that by dialing back all AC components back after stabilizing, the parts of the circuit that will start the oscillator to run in reality are carefully balanced on a knife edge. If you add the smallest transition, impusle to the circuit after t0 the oscillation should start.

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