Performance analysis of three-phase inverters controlled by synchronous delta-modulation systems

It is shown that the output current harmonic distortion and average switching frequency of synchronous delta-modulation (DM) systems can be calculated analytically in spite of the quasi-stochastic behavior of the modulator output. Under the assumption of constant link frequency and a large ratio of link to output frequency, results are derived for three-phase sigma-delta modulation, space-vector-based sigma-delta modulation, and current regulated DM. The results hold for any shape of the inverter input voltage (including DC). The output current harmonic distortion of resonant link inverters is compared with that of conventional hard switching of pulse width modulation (PWM) inverters