In series inverter, the resonating elements L-C(commutating elements in thyristor inverter)are introduced in series with the load. Thisconstitutes a series resonate circuit, where theload (R) is purely resistive. This type of inverterproduce an approximately sinusoidalwaveform at resonating frequency. Because ofIGBT (instead of SCRs) does not suffer fromthe problem 'commutation' , hence the maximumfrequency operation can be obtained.