Application of pulse-ratio-modulation to fixed frequency sinusoidal tracking inverters

The paper concerns the application of pulse-ratio-modulation techniques in the field of fixed frequency inverters with sinusoidal output waveform. In particular, the criteria are analyzed to choose the parameters of the output filter and of the compensation network and a comparison is effected between the results obtained by employing either the aforesaid modulation technique or a fixed frequency pulse-width-modulation technique. The comparison, effected by simulation, has taken into account also a non-linear load and it has shown that the employment of the pulse-ratio-modulation technique allows a remarkable reduction of the inverter supply overvoltage necessary to use tracking control techniques with high modulation frequencies. Lastly, the results obtained by simulation have been confirmed by a prototype.