Harmonic minimization in delta modulated inverters using tuned filters

The integrator in the modulator of delta PWM inverters acts as a filter to estimate the input reference signal from the output waveform for comparison purposes. The use of a tuned filter allows the online variation of filter cutoff frequency and ensures minimization of desired harmonics from the output of the inverter. This method is particularly suitable for delta-modulated inverters used in variable-frequency applications. The modulator's harmonic performance has been studied using a windowed discrete Fourier transform. The theoretical results were verified experimentally. The significance of the modulator lies in its simplicity, versatility, and ease of online harmonic minimization, which is achieved without predetermination of the switching points.<<ETX>>