Comparison of specially connected transformer scheme and five leg inverter for five phase supply

Whenever a Three Phase Induction Motor is run, a problem with ripple torque & harmonics. This hampers the smooth operation of the machine and is found also aggravates the amount of heat that is generated. The ripple content can be smoothened by supplying the motor with a multi-phase supply which is greater than the three phase supply. Selection of an even number of phases should be avoided because it degrades the performance of the motor as the poles coincide with each other. Care must be taken so that the number of phases is not multiples of three. Therefore, a Five Phase Supply may be preferred. This paper proposes a Five Leg Inverter which is better than a specially connected transformer to convert a three phase grid supply to a five phase supply. Output of the five leg inverter is controlled by sinusoidal Pulse Width Modulation technique to bring a variable as well as a constant voltage and frequencies. It is highly Economical, has more Efficiency and good control compared with special design of transformer scheme.