Inverter means a power converter which converts D.C. power to A.C. power. The type of output waveform defines that whether it is square wave or Sine wave invrter.

Generally square wave inverter is simple to make. Less complex while testing and trouble shooting and cost effective by design. This is the most popular type of topology typically used in the home inverter segment.

The topology used in this type is called as PUSH PULL type of inverter.

Design comprises of a frequency generator, pulse width controller, two complementary outputs with dead band, feedback circuit with error amplifier, battery voltage monitoring circuits, load current and battery current sensing circuits, line voltage monitoring, change over mechanism, audio visual indications, reset / start switch etc. Circuits can be made using analog and digital ICs or by using microcontrollers. Experience says that using microcontroller based design proves to be more precise, less component count increasing reliability, compact in size, copy protected.

Magnetics design is crucial as the price to performance ratio is to be maintained without loosing focus on quality. Transformer forms the major component in the inverter design. It is used to convert low voltage high current A.C. at input to High voltage low current output in inverter mode. While on line mode or mains mode it charges the battery by controlling the secondary voltage. For charging the battery either Triac or SCRs are used as switching element.

Normally 12 VDC or 24 VDC is most common D.C. input voltage and the battery used is of 12 V- 100 Ah to 200 Ah capacity. The expected back up time is for 3 hours to 8 hours for full load.