How to make this inverter output voltage stable

Thread Starter

Insidcircuit.

Joined Oct 9, 2022
16
The circuit diagram below is an inverter that has an output voltage ranging from 110 to 200 volt AC. My problem is anytime I turn it on the output voltage keeps going on and off which is not stable. I need Screenshot_20230101-224028.jpgyour help to solve this problem. Your solutions will be highly appreciated.
 

MisterBill2

Joined Jan 23, 2018
19,474
I would not call that an actual "inverter" circuit. It is a simple driven transformer power supply.
An actual inverter typically uses the transformer as a portion of the oscillator circuit. At it's best, that circuit will have very poor regulation.
Without voltage sensing feedback it can not have good regulation.
 

crutschow

Joined Mar 14, 2008
34,855
You are generating single-polarity pulses into the transformer which generates an average voltage in the primary, which likely is saturating the transformer core.
You need to apply equal plus and minus voltage pulses to the primary, or couple the pulses through a large capacitor to block any DC component of the pulses.
 

Thread Starter

Insidcircuit.

Joined Oct 9, 2022
16
Why would you want to build this circuit?
What type of 110-200VAC device are you trying to power?
I'm using it to power led bulbs and mobile charger as well but the output voltage is not because if I plug in the led bulb or the charger it keeps going on and off.
 

Thread Starter

Insidcircuit.

Joined Oct 9, 2022
16
You are generating single-polarity pulses into the transformer which generates an average voltage in the primary, which likely is saturating the transformer core.
You need to apply equal plus and minus voltage pulses to the primary, or couple the pulses through a large capacitor to block any DC component of the pulses.
Thanks for your reply can you support it with a diagram?
 

MrChips

Joined Oct 2, 2009
31,107
You are trying to take 12VDC to 110VAC and back down to some DC voltage?
Do you know what your efficiency is going to be?
I bet you that it is not going to be very high.
 

DickCappels

Joined Aug 21, 2008
10,247
Not only that, but as already pointed out, unless this is a flyback design (I suspect the transformer is not designed for anything fast) it won't work because of the waveform into the primary as @crutschow mentioned in post #3

By the way, below is the symbol Vishay uses for your FET:
1672646145126.png
 

Ian0

Joined Aug 7, 2020
10,277
Does your transformer have a gap? It's not going to work with a standard off-the-shelf transformer, because the transformer will immediately saturate.
If you want to build a simple inverter, then use a SG3525 and two MOSFETs.
Alternatively, LED lamps and battery chargers will run off a DC supply, so you could make a single transistor flyback circuit to give 160V DC or 325V DC.
But @MrChips makes a very good point that converting to 230V then back to low-voltage DC is very inefficient. Car-chargers are available for most mobile telephones, and 12V LED lamps are available, and that would make things much more efficient.
 

MisterBill2

Joined Jan 23, 2018
19,474
That same circuit, with a diode and filter cap added, is presented as a high voltage power supply in some reputable sites. It is not suitable for replacing a mains voltage source, except for powering things like a soldering iron or incandescent light bulb. It still is not really an inverter circuit.
 

MisterBill2

Joined Jan 23, 2018
19,474
That second circuit in post #13 is the one most likely to deliver good power and have adequate regulation. The first circuit is very creative and certainly can be adjusted to perform well, but that will require a scope to set the duty cycle of the 555 to produce a symetrical wave. And with a 555 changing the resistors will affect the frequency a bit. So the adjustment process will be complicated.
 
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