voltage controller feedback

[jean12]

Hello there,can you please help me to design a voltage controller feedback so that the voltage don't drop down when I apply a high load on the AC supply of my dc-ac converter?

I designed a dc-dc-ac converter:12VDC-440VDC-220VAC but when applying a load on the output the voltage drops,can you please help me to make a stabiliser with the voltage feedback?

Thanks,please help.

 

[BradtheRad]

Have you made certain there is little resistance in your wiring and components?

The wires carrying 12V must be thick enough to carry the current with little voltage drop.

The switching devices (mosfets) must turn on sufficiently so that they do not drop much voltage.

Etc.

 

[jean12]

so how the output voltage will be stabilized at 220VAC for differents load applied?

Please help.

 

[BradtheRad]

To regulate the output voltage, you need to construct a regulating stage for your converter.

(This is a different issue from solving your voltage drop with a heavy load.)

The easiest way to regulate is probably to increase or decrease the amount of current drawn from your 12V supply.

This can be done by altering the duty cycle in your first converter (DC-DC). For a heavy load, you would increase the duty cycle so that the output is a few volts higher, since it will drop some as it goes through your H-bridge.

There are IC's made to do this sort of thing. Or else an op amp (or two) would be the core of such an automatic regulator.

 

[kabeer02]

What type of oscillator do you used?

 

[jean12]

PWM with PIC16f1827,I am controlling an H_bridge which must give 220VAC but also I am asking my self why am I not getting the 220VAC?whne applying 270VDC on the H_bridge?

Please help.

 

[jean12]

Dear BradtheRad,can you please help me to do that regulation?

Thanks.!!

 

[BradtheRad]

What is the output voltage when you apply a light load? Is it what you expect? Does it go down progressively as you increase the current drawn?

Remember that whatever the amount of current you wish to draw at 220V, your 12V supply must provide 20 times that amount of current.

Is your waveform a sinewave? This means more effort because you must adjust the control waveforms so that they only turn on two mosfets/transistors at at time. The aim is to prevent shoot-through (short circuit) from supply directly to ground.

 

[jean12]

What is the output voltage when you apply a light load? Is it what you expect? Does it go down progressively as you increase the current drawn?

Remember that whatever the amount of current you wish to draw at 220V, your 12V supply must provide 20 times that amount of current.

Is your waveform a sinewave? This means more effort because you must adjust the control waveforms so that they only turn on two mosfets/transistors at at time. The aim is to prevent shoot-through (short circuit) from supply directly to ground.

Hello,the output I have is not a pure sine wave but when applying a light load the output voltage drops.

 

[BradtheRad]

You need to find which component has excessive resistance.

Somewhere you have a voltage drop across one or more of:

* wire
* connector
* switching device (mosfet/transistor)
* coil, transformer

You must measure the voltage drop across each component, during the part of the cycle when it is conducting. An oscilloscope is invaluable here.