A simple 200 watt inverter circuit without a transformer (transformerless) has been discussed in this article, using a 310V DC input. It is a sine wave compatible.
Inverters as we know are devices which convert or rather invert a low voltage DC source to a high voltage AC output.
The produced high voltage AC output is generally in the order of the local mains voltage levels. However the conversion process from a low voltage to high voltage invariably necessitates the inclusion of hefty and bulky transformers. Do we have an option to avoid these and make a transformerless inverter circuit?
Yes there is a rather very simple way of implementing a transformerless inverter design.
Basically inverter utilizing low DC voltage battery require to boost them to the intended higher AC voltage which in turn makes the inclusion of a transformer imperative.
That means if we could just replace the input low voltage DC with a DC level equal to the intended output AC level, the need of a transformer could be simply eliminated.
The circuit diagram incorporates a high voltage DC input for operating a simple mosfet inverter circuit and we can clearly see that there's no transformer involved.
Simulation and Working
The high voltage DC equal to the required output AC derived by arranging 18 small, 12 volt batteries in series.
The gate N1 is from the IC 4093, N1 has been configured as the oscillator here.
Since the IC requires a strict operating voltage between 5 and 15 volts,the required input is taken from one of the 12 volt batteries and applied to the relevant IC pin outs.
The entire configuration thus becomes very simple and efficient and completely eliminates the need of a bulky and heavy transformer.
The batteries are all 12 volt, 4 AH rated which are quite small and even when connected together does not seem to cover too much of space.They may stacked tightly to form a compact unit.
The output will be 110 V AC at 200 watts.
Q1, Q2 = MPSA92
Q3 = MJE350
Q4, Q5 = MJE340
Q6, Q7 = K1058,
Q8, Q9 = J162
NAND IC = 4093,
D1 = 1N4148
Battery = 12V/4AH, 18 nos.
Upgrading into a Sinewave Version
The above discussed simple 220V transformerless inverter circuit could be upgraded into a pure or true sinewave inverter simply by replacing the input oscillator with a sine wave generator circuit as shown below:
Parts List for the sinewave oscillator can be found in this post