The method of commutation is of fundamental importance in an invertor, and good commutation makes for successful operation of the circuit. This paper describes an improved method of commutation for the parallel-type invertor, using two separate capacitors to store energy instead of one as in the conventional circuit. These capacitors are also used to bypass voltage transients which might go through the thyristors. An analysis of a single-phase parallel invertor is given, and the operation of a 3-phase invertor formed by three single-phase circuits is also described.