Power inverters in the range of KVA, requires huge current transferring capabilities for implementing the required operations as per the desired specs of the unit.
Transformer being the main power making component of such an inverter, requires high current handling secondary winding if the used battery voltage is at the lower side, for example 12 or 24 volts.
In order to optimize the transformer at lower currents, the voltage needs to be pushed at higher levels which again becomes a problematic issue, because higher voltage means putting batteries in series.
The above problems can definitely demoralize any new electronic hobbyists or anybody who might be planning to make a rather big inverter design, may be for controlling the whole house electrical.
An innovative approach for make things simpler even with huge power inverter designs has been discussed in this article which uses smaller discrete transformers with individual drivers for implementing a 2000 VA inverter circuit.
Let's study the circuit diagram and it's operations with the following points:
Basically the idea is to divide the power into many different smaller transformers whose outputs can be fed to individual sockets for operating the relevant electrical appliances.
This method helps us to avoid the need of hefty and complicated transformers, and the proposed design becomes feasible even for an electronic novice to understand and construct.
Four IC4049s have been employed in this design. A single 4049 consists of 6 NOT gates or inverters, so in all 24 of them have been used here.
Two of gates are wired up for generating the basic required square wave pulses and the rest of the gates are simply held as buffers for driving the next relevant stages.
Each transformer utilizes a couple of gates and the respective high current Darlington transistors which function as the driver transistors. The associated gates conduct alternately and drive the transistors in accordance.
The mosfets which are connected to the driver transistors respond to the above high current signals and start pumping the battery voltage directly into the winding of the respective transformers.
Due to this an induced high voltage AC starts flowing through the complementary output winding of all the involved transformers, generating the required AC 220 V or 120 V at the respective outputs.
These voltage become available in small pockets, so only the relevant magnitude of power can be expected from each of the transformers.
The 555 section takes care of the square wave output generated from the oscillator stage such that these are broken into sections and optimized for replicating a modified sine wave output.
All the parts after POINT X should be repeated for acquiring discrete power output sections, the common input of all these stages must be joined to POINT X.
Each of the transformer may be rated at 200 VA, so together, 11 stages (after pointX) would provide roughly outputs up to 2000 VA.
Though using many transformers instead of a single might look like a small drawback, the actual need of deriving 2000 VA using ordinary parts and concepts finally becomes achievable from the above design very easily.