Application of Pulse Ratio Modulation to Fixed-Frequency Sinusoidal Tracking Inverters

The application of pulse ratio modulation techniques in the field of fixed-frequency inverters with sinusoidal output waveforms is discussed. In particular, the criteria for choosing the parameters of the output filter and of the compensation network are analyzed, and a comparison is effected between the results obtained by employing either the aforementioned modulation technique or a fixed-frequency pulsewidth modulation technique. The comparison, effected by simulation, has also taken into account a nonlinear 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.